Nuclear Weapons Safety


No Design Changes Are Warranted

A Review for Tri-Valley CAREs
by Greg Mello
July 1, 1995

I am pleased to report the stockpile today is safe, secure, reliable, and meets current military requirements.  We make that statement with confidence today and for the immediate future ... our stockpile is becoming safer and more reliable simply because we are retiring older weapons ... Thus, we should enter the 21st century with a modern, safe, and reliable stockpile consistent with the demands of START I and with anticipated military requirements. 

-- Dr. Harold Smith, Assistant to the Secretary of Defense for Atomic Energy, to Congress on March 15, 1994.

In addition to reducing the sheer size of the active nuclear inventory, a number of additional actions have been or are being taken to improve nuclear safety, security, and use control ... I can confidently report today that the stockpile is safe, secure, and reliable.  It also meets the requirements of DoD and the Services.

-- Dr. Smith to Congress on March 1, 1995

Nuclear Weapons Safety:  No Design Changes Are Warranted

An Issue Brief for Tri-Valley CAREs
by Greg Mello
July 1, 1995

  • The quest to make nuclear weapons "safe," in the fullest sense of the term, can never succeed and guarantees large appropriations without clear results.

  • Weapons in the current U.S. arsenal are, technically speaking, safe and becoming more so as older weapon types are retired.  Here, "safe" means that all the weapons in the START II stockpile are fully protected against accidental nuclear explosion. 

  • It is impossible to reduce the risk from nuclear weapons accidents to zero, however, and in particular there will always remain some risk that plutonium will be dispersed by fire or explosion.  The simplest and best ways to further minimize this possibility are 

    • operational and deployment changes that reduce the chances of an accident and the risk to the public should there be one; and

    • further retirements, leading to a smaller arsenal. 

  • The safety concerns raised at the beginning of this decade by the Drell panel have been mostly resolved by retirements and by changes in handling procedures.  Dr. Drell now believes that changes in the design of the nuclear components of weapons to achieve greater safety are not warranted, given the reliability, arms control, and nonproliferation costs of such changes. 

  • While it would in theory be possible to replace some warheads in the arsenal to make them safer still, neither the Air Force nor the Navy, nor the Department of Defense (DOD), nor the Department of Energy (DOE) believes this action is merited.  Therefore no warhead replacements for safety are currently planned.

  • No safety problems are expected to occur in the aging process.

  • The proliferation risks of upgrading the U.S. arsenal for any purpose, safety included, are potentially great.

  • If the countervailing risks resulting from weapons testing, production, waste management, and eventual decommissioning and cleanup are included, it is highly likely that efforts to produce "safer" weapons will degrade overall nuclear safety.

  • Attempts to upgrade safety will decrease reliability, because new designs cannot be tested.

  • None of the proposed new science-based stockpile stewardship (SBSS) facilities is needed to maintain the safety of existing nuclear weapons.  Most proposed facilities, like the National Ignition Facility at Livermore, the Atlas facility at Los Alamos, and the Jupiter facility at Sandia, have no safety-related missions at all. 

  • The safety benefits per dollar spent on weapons safety upgrades are several orders of magnitude smaller than other federal safety investments, civilian or military. 

  • Morbidity and mortality in the cleanup crews at nuclear weapons accidents have not been studied, and long-term effects at these sites are unknown.  With these possible exceptions, no one is known to have ever been injured from a nuclear weapon in an accident. 

  • The risk of death from a nuclear weapons accident appears to be, very roughly, about a million times smaller than other causes of accidental death and about 100-1000 times smaller than the public health risks from exposure to environmental pollution at current health standards.

  • The real purpose of the disproportionate and irrational drive to maximize safety in just one part of a complex and countervailing system of risks is to make nuclear weapons jobs and funding, and not the public, safe.

  • For all these reasons, weapons safety concerns need not and should not drive the stockpile management program. 

1.  Introduction 

"Safe" is hardly the first word anyone would choose to describe nuclear weapons.  After all, nuclear weapons have been designed and amassed precisely because they are enormously destructive, i.e. because they are not "safe."  From the outset, it is obvious that the oxymoronic quest to make nuclear weapons "safe" can never succeed.  To adopt such a quest as a goal of public policy is a way of assuring that no amount of money, however large, will ever be adequate to complete the job.  What might be called "existential safety" for nuclear weapons will never be achieved. 

Yet, if the problem of nuclear weapons safety is defined in the narrow sense of preventing accidental detonation of the weapons or dispersal of their nuclear materials, there is a consensus among authorities that current nuclear weapons are safe -- if not absolutely so then at or near the practical limit of safety.  What might be called "practical safety" for nuclear weapons has already been achieved.

The contradiction between what has already been achieved and what can never be achieved has been harnessed by the Department of Energy (DOE) to produce enormous amounts of rhetoric.   Where logic has faltered, the nuclear weapons orthodoxy demands faith, and to this end maintaining andimproving the "safety, security, and reliability" of the nuclear arsenal has become a constant litany that is ritually intoned to ensure support of the DOE's science-based stockpile stewardship (SBSS) program.  This slogan is offered with little or no further explanation by the weapons laboratories and their sponsors whenever appropriations are questioned.  Of the "safety, security, and reliability" trinity, it is the quest for endlessly "safer" nuclear weapons that has retained the most political cachet, pandering as it does to existential fears whose solution entirely transcends further technical adjustments in weapons design.

The central theme of this paper is that nuclear weapons safety, as a technical problem for weapons designers, has been solved.  Additional operational changes offer some further reductions in risk, but risks from nuclear weapon accidents are already orders of magnitude lower than in the recent past.  Not only will further efforts to improve weapons safety be expensive and lead to greatly diminished returns in risk reduction, but when the safety issue is placed in its overall context, such "improvements" are shown to decrease overall nuclear safety. 

At the same time, replacing selected weapons in the arsenal to "improve" safety will inevitably decrease reliability if the new weapons are not proof-tested.  For these reasons, nuclear weapons safety is not an absolute good.  The proper goal is an optimum level of nuclear weapons safety, not a maximum.

In some respects, the problem of "How safe is safe" is similar to the problem of "How clean is clean" -- completely safe and clean are not the right answers.  But there are differences:  the nuclear weapons problem is relatively easy to solve politically, technically, and managerially; it has been a central goal since 1944; and it has been accomplished. None of these apply to the cleanup problem.

Often nuclear weapons safety and security are spoken of together, the two concerns being combined in the term "surety," which sometimes includes reliability concerns as well.  With the planned addition of permissive-action links (PALs) to submarine-launched ballistic missiles, adequate use-control over the entire U.S. nuclear arsenal will in time be achieved. (1) Security will not be discussed in this paper.

2.  The Drell panel 

In December 1990, the Report of the Panel on Nuclear Weapons Safety, usually called the Drell Report after its chairman, Dr. Sidney Drell, published its strong recommendations for a greater emphasis on safety in nuclear weapons design and deployment and in the institutional arrangements governing weapons. (2)   In brief, the Drell panel found that some weapons in the U.S. stockpile were not as safe from accidental detonation as had been thought (the particular weapons systems involved were kept vague).  The panel also observed that most of the weapons in the stockpile were not equipped with state-of-the-art features to prevent plutonium contamination in the event of an explosion or fire.

To remedy these problems, Drell called for operational changes, some of which were quickly implemented, and the incorporation of the most modern safety features into all stockpiled weapons.  To fully implement this latter recommendation for the large and diverse 1990 stockpile would have required dozens of underground nuclear tests and tens of billions of dollars in appropriations for weapons design and manufacturing.  It would have required the construction of a new nuclear weapons manufacturing complex and the operation of that complex over an extended period of time, and it would have required the costly modification of some delivery platforms.

Thus, although the scope of the panel's investigation was ostensibly technical, its recommendations called for an enormous amount of new work (and new funding) for DOE's nuclear weapons program and its laboratories, just as the Cold War was winding down.  Fortunately, Drell's most expensive and controversial recommendations were mooted by events which led to the retirement of some weapon systems and the stand-down of others.

The first of these events was the START I treaty, signed by the United States and the Soviet Union in July of 1991, followed by the "joint understanding" in June 1992 which led to START II in January of 1993.  Major reductions in the deployment of tactical nuclear weapons were announced by the U.S. and Soviet Union in the fall of 1991, together with the removal of nuclear weapons from bombers on alert.  In 1992, President Bush announced that there was no need for further U.S. nuclear weapons tests to develop new weapons, and in July of 1993, President Clinton joined the Russian-led moratorium on nuclear testing. 

In addition to improving nuclear weapons safety, all these changes collapsed the central mission of the DOE weapons labs, which had been the design of new weapons.  The result has been that, even though the nuclear arsenal has become markedly safer, the labs and DOE are all the more voficerously clamoring for "more" safety as a new mission.  "Safety" has thus become more and more of an empty slogan as it expands into the vacuum of purpose that characterizes large portions of the laboratories.

3.  All authorities agree:  U.S. weapons are safe 

Are U.S. nuclear weapons, in fact, "safe?"  The unequivocal and unanimous conclusion of the nuclear weapons establishment is affirmative.  In his testimony on March 15, 1994, Dr. Harold Smith, Assistant to the Secretary of Defense for Atomic Energy, told Congress, 
    I am pleased to report the stockpile today is safe, secure, reliable, and meets current military requirements.  We make that statement with confidence today and for the immediate future ... Our stockpile is becoming safer and more reliable simply because we are retiring older weapons ... Thus, we should enter the 21st century with a modern, safe, and reliable stockpile consistent with the demands of START I and with anticipated military requirements.  (3)
This statement was made in the presence and with the approval of Dr. Victor Reis, Assistant Secretary of Energy for Defense Programs, who added,
    Right now, as Dr. Smith said, that stockpile is safe and reliable.  (4)
Dr. Reis and Dr. Smith are, respectively, a member (one of three) and the Executive Secretary and Staff Director of the Nuclear Weapons Council.  There is no higher or more integrative authority on this subject.  And what they said has been a consistent theme over the past few years.  Smith's predecessor, Robert Barker, told the Senate in March of 1992,
    The Air Force and Navy, in cooperation with the Office of the Secretary of Defense and the Energy Department, evaluated the safety of all ballistic missiles that carry nuclear warheads.  It was determined that there is not now sufficient evidence to warrant our changing either warheads or propellants.  (5)  

John Deutch, now Deputy Secretary of Defense, reiterated Barker's general conclusion for the specific case of the W88 warhead on May 3, 1993 when he told the House Panel on the Military Application of Nuclear Energy that incorporation of insensitive high explosive (IHE) into that warhead would not be worth its considerable cost (more than $3 billion).  (6)

A few days later, Rear Admiral John T. Mitchell, Director, Strategic Systems Programs Office, U.S. Navy, was even more blunt.  On May 11, 1993, he told a Senate committee that, for the W88 warhead, "We believe that there would be no gain in safety in changing to insensitive high explosive."  (7)   These comments by Deutch and Mitchell signalled that the safety questions that had been raised by the Drell Report regarding the W88 (see below) had been resolved, at least to the satisfaction of the DOD and the Navy.  (8)

Deutch, a strong advocate of nuclear weapons design and testing, recently reiterated the government's consensus on the safety of U.S. nuclear weapons.  On October 5, 1994, Chairman Hamilton of the House Foreign Affairs Committee suggested to Deutch, following the latter's presentation of the Nuclear Posture Review, that safety concerns might be a reason to resume nuclear testing. Deutch demurred, saying unequivocally, "It is my judgment that all the nuclear weapons that we have are adequately safe." 

Dr. Smith unambiguously reiterated the continuing safety theme on March 1, 1995, in testimony before the Senate Appropriations Committee, Energy and Water Development Subcommittee.
    In addition to reducing the sheer size of the active nuclear inventory, a number of additional actions have been or are being taken to improve nuclear safety, security, and use control ... I can confidently report today that the stockpile is safe, secure, and reliable.  It also meets the requirements of DoD and the Services.
The repeated testimony cited here was offered by the highest responsible sources after careful review of those portions of the Drell Panel's recommendations that remain outstanding.  This testimony states with abundant clarity that no safety problem currently exists in the nuclear weapons stockpile.  Yet, since the weapons labs still hawk greater "safety" as a mission, many decisionmakers conclude that nuclear weapons safety is an unresolved issue. (9)

4.  What is the nuclear weapons safety problem? 

Those responsible for designing, building, and maintaining U.S. nuclear weapons do so with a keen appreciation of the dangers inherent in these weapons and in the materials they contain.  It is their job to make the protection of public safety a paramount concern in every aspect of their work.  Their real goal is to effectively protect the public, not simply to build safer weapons at any cost.  These two goals are not the same, as can be seen from the following outline, which supplies a common-sense context for analyzing the safety problem and maximizing the safety benefits of federal spending. 

The Nuclear Weapons Safety Problem in Context

   The Overall Goal:  Protect the public (10)
    A.  from dangers other than those from nuclear weapons

    B.  from nuclear weapons dangers (DOE: "reduce the nuclear danger" (11)), including
      1.  nuclear attack

        a.  by an existing nuclear-weapons state
        b.  by a proliferant nation or group

      2.  risks to workers from nuclear weapons testing, manufacture, waste management, deployment, decommissioning and decontamination, and cleanup

      3.  risks to public health from the nuclear weapons operations listed above

        a.  risks to current populations
        b.  risks to future generations

      4.  any environmental risks not included in 3, such as loss of tribal lands and sites, environmental damage that is not human health damage per se

      5.  other, indirect, nuclear dangers (e.g. threats to democracy from counterterrorism activities)
      6.  nuclear weapons accidents

        a.  unintentional nuclear detonation
        b.  dispersal of plutonium 

Based on this outline, there are three relevant hierarchical levels of safety goals.  The most fundamental goal is maximizing overall public safety.  This means to minimize morbidity and early mortality, from whatever cause.  Since it is clear that there is a finite amount of money available to the federal government to do this, it is certain that seeking to maximize safety from one type of danger without regard to cost, e.g. nuclear weapons, would damage overall public safety, not to mention impede other important goals of government.  Choices will have to be made, then, and an optimum, not a maximum, level of safety chosen for each particular program, nuclear weapons included. 

A subset of public safety is safety from nuclear weapons.  Optimizing this -- which is called by DOE "reducing the nuclear danger" -- means to minimize morbidity and mortality from nuclear weapons operations taken as a whole:
the production, storage, processing, and manufacturing of weapons materials, and the design, production, maintenance, deployment, and disassembly of the weapons themselves.  It includes the public health aspects of waste management, as well as environmental restoration or the lack of it.  It includes safety from any intentional use of nuclear weapons, and from nuclear accidents. 

But since only a very limited amount of money is available for this task, it is possible, even certain, that seeking to reduce any one aspect of the nuclear danger without regard to cost -- either cost in dollars or in environmental or proliferation risks -- could well increase, not decrease, the overall nuclear danger.

Finally, a subset of safety from the dangers of nuclear weapons is safety from nuclear weapons accidents, which is served by the incorporation of safety features into the design of nuclear weapons systems.  It is also served by operational changes that decrease the likelihood of accidents or the public health exposures from accidents, should any occur.
Thus the technical or design aspect of weapons safety is an important goal, but it is a subservient one.  A sense of proportion is required.  An optimum, not a maximum, amount of nuclear weapons safety is the inevitable and proper goal.

At present, however, the DOE weapons labs are promoting the quest for greater nuclear weapons safety as if it were an absolute good -- as if it had no conflict with the other goals of the agency or with the other goals of the government as a whole.  The damage that this quest could do to those larger goals is discussed briefly below, following a summary of the technical aspects of nuclear weapons safety.

5.  Design aspects of nuclear weapons safety 

In a nutshell, the nuclear weapons safety problem as it affects the design laboratories consists of minimizing the probability of two general kinds of untoward events:
    1) unintentional nuclear detonation of a weapon, either from 
      a) accidental activation of the firing circuits (e.g. by lightning or other electromagnetic pulse) or from 

      b) accidental detonation of the high explosive (HE) in the primary from an impact, fire, or other non-electrical cause; and

    2) dispersal of plutonium due to an accident of any kind. (12)

The following discussion reviews each of these safety concerns in turn, and concludes with an overview of problems related to aging of weapons. 

A.  Accidental activation of the firing circuits is a problem that has been solved

Electrical safety in U.S. weapons is addressed by means of a protection policy known as Enhanced Nuclear Detonation Safety (ENDS), which is achieved by a technology called Enhanced Electrical Isolation (EEI).  The Drell Panel describes this system in detail.
      The ENDS is designed to prevent premature arming of nuclear weapons subjected to abnormal environments.  The basic idea of ENDS is the isolation of electrical elements critical to detonation of the warhead into an exclusion region which is physically defined by structural cases and barriers that isolate the region from all sources of unintended energy.  The only access point into the exclusion region for normal arming and firing electrical power is through special devices called strong links that cover small openings in the exclusion barrier ... Detailed analyses and tests give confidence over a very broad range of abnormal environments that a single strong link can provide isolation for the warhead to better than one part in a thousand.  Therefore, the stated safety requirement of a probability of less than one a million ... requires two independent strong links in the arming set, and that is the way the ENDS system is designed ... both strong links have to be closed electrically -- one by specific operator-coded input and one by environmental input corresponding to an appropriate flight trajectory -- for the weapon to arm.

    ENDS includes a weak link in addition to two independent strong links in order to maintain assured electrical isolation at extreme levels of certain accident environments, such as very high temperature and crush.  Safety weak links are ... designed to fail, or become irreversibly inoperable, in less stressing environments than those that might bypass and cause failure of the strong links.

    The ENDs system provides a technical solution to the problem of preventing premature arming of nuclear weapons subject to abnormal environments ... ENDS was developed at the Sandia National Laboratory in 1972 and introduced into the stockpile starting in 1977. (13) (emphasis added)
While there are some older weapons in the U.S. arsenal that do not contain ENDS, these weapons are currently being retired. (14)   With these retirements, the problem of electrical safety of U.S. nuclear weapons has been solved.  Note that the one-in-a-million standard applies in the case of accidents, which are themselves infrequent, and not in routine operations.  The applicable specification for the probability of an accidental explosion during normal operations, including all environments in the stockpile-to-target sequence, must be less than 10-9 per warhead lifetime. (15)    Since the probability of a highly abnormal environment, i.e. an accident, is now much lower than it was during the Cold War with its intensive airborne transport of nuclear weapons, projects to develop firing circuits with still greater isolation possess only very small benefits.

Such work is, in any case, unlikely to affect the nuclear components -- the physics package -- of the warhead.  It is primarily Sandia which designs and maintains the arming and safing systems of warheads, not the two physics labs.  Modifications to these electrical systems are relatively routine and need not trigger major stewardship expenses.

B.  The possibility of an accidental nuclear explosion due to impact or fire has been the subject of intensive study and is extremely unlikely

The second aspect of preventing an accidental nuclear explosion consists in ensuring that impacts, fires, explosions, and any other causes not covered by the electrical safety system cannot set off any weapon's high explosive in such a way that any significant nuclear yield results.  Recognition of this danger led to the adoption of the so-called "one-point-safety" standard in 1968.  This quantitative standard requires all weapons in the stockpile to be "one-point safe," which is defined as achieved if the probability of a nuclear explosion with a yield of four pounds TNT-equivalent or greater from detonation of the HE at any single point is less than one in a million in an accident. (16)   And this safety performance must be intrinsic to the design, i.e. it must obtain in the absence of any mechanical safing device. (17)  

Using more detailed computational analysis than had previously been available, the Drell Panel found that "unintended nuclear detonations present a greater risk than previously estimated (and believed) for some of the warheads in the stockpile." (18)   To solve these problems, the Drell Panel recommended a major competitive effort at the weapons laboratories to design new warheads.  Yet other than an implicit recommendation to quickly retire the SRAM-A system (19) and make sure the entire stockpile has ENDS, the unclassified Drell Report contains no specific recommendations for improving the nuclear detonation safety of the U.S. arsenal. 

However, the report did recommend a broad and in-depth review of the safety of the Trident II (D5) missile system, given the fact that the W88s used there do not contain IHE and are mounted in a ring around the third-stage rocket motor, which contains a detonatable propellant.  Kidder concurred with this recommendation and suggested that the Trident I (C4) W76 system be closely examined as well. 

The results of the examination, which set these worries to rest, were provided to Congress in the testimony quoted above.  Meanwhile, operational changes in the way Trident missiles were loaded into submarines were immediately implemented.  Trident missiles are no longer loaded into their launching tubes with their warheads in place, which means, according to Drell, that there is now "no worry" about a dockside warhead explosion. (20)

C.  To prevent plutonium dispersal, operational changes are most effective
Plutonium -- capable of causing cancer deaths from doses in the microgram range -- can be dispersed into the environment in any accident in which the conventional explosive in a nuclear weapon burns or explodes.  If the explosive involved is IHE, an explosion is highly unlikely, since IHE is remarkably difficult to detonate.  In the case of a fire, the plutonium will burn along with the IHE.  Warheads made with HE may also burn in a fire rather than explode, and in fact this happened six times at U.S. Air Force bases between 1958 and 1965 when nuclear warheads were involved in fires. 

The only good news here is that, in the absence of an explosion, the mean particle size of the plutonium oxide produced is larger and less likely to be inhaled, and is dispersed over far less area, resulting in many fewer potential casualties. (21)   The Air Force in fact claims that these six accidents resulted in only localized contamination, which was cleaned up in some fashion in each case. (22)
All in all, between 1950 and 1980 there were 32 serious nuclear weapons accidents ("Broken Arrows").   None have occurred since 1980.   During that 30-year period there were two accidents that involved explosions with plutonium. (23)   These were airplane crashes at Palomares, Spain in 1966 and at Thule, Greenland in 1968.  Luckily, these occurred in relatively unpopulated areas, and no major public exposures resulted.  It seems likely, however, that significant danger was experienced by the cleanup crews, which were probably not well trained or equipped, both in these cases as well as in the six accidents in which weapons burned. 

Can the possibility of nuclear weapons accidents in which plutonium is dispersed be eliminated?  The answer, of course, is no.  Even with IHE, with fire-resistant pits (FRPs, which have a refractory shell (24)  surrounding the plutonium), and with speculative "super-safe" designs in which the fissile material is somehow kept separate from the HE or IHE until the arming sequence -- there will always be a finite chance of plutonium dispersal in the event of a fire or other accident.  And this finite chance will continue to be much greater than the one-in-a-million standard adopted for electrical isolation and for one-point safety. 

Still, the dangers from plutonium dispersal, while quite serious, are far less than those from a nuclear detonation.  Claims by lab officials that a plutonium dispersal accident could be "worse than Chernobyl" are at least two orders of magnitude off base. (25)

In order to prevent plutonium dispersal, the Drell committee recommended that "all nuclear bombs loaded onto aircraft -- both bombs and cruise missiles -- [be built] with both IHE and FRPs."  On its face, this had some appeal, since some 84 percent of serious nuclear weapons accidents have involved aircraft. 

Unfortunately, equipping all airborne U.S. weapons with IHE and FRPs would require redesigning and rebuilding thousands of nuclear weapons, entailing dozens of nuclear tests and the construction of new nuclear weapons factories, such as a replacement for Rocky Flats.  Kidder's more practical recommendation was, instead, to implement cost-saving operational changes that would reduce the risk of accidents which could result in plutonium dispersal to near zero.  These changes basically consist of not putting nuclear weapons on aircraft in peacetime, eliminating the possibility of any aircraft accident leading to plutonium dispersal.  Carson Mark, Director of the Theoretical Division at Los Alamos for 26 years, had argued a month before Drell that operational limitations on warheads (e.g. no routine deployment for airborne weapons) would be far more cost-effective than redesigning them to, for example, incorporate IHE. (26)

Removing nuclear weapons from aircraft has now largely been effected.  In September of 1991, not long after Kidder's study, President Bush decided to take all U.S. strategic bombers off alert, meaning that all U.S. airborne strategic nuclear weapons have now joined U.S. tactical nuclear weapons in secure storage bunkers, out of harm's way.  President Bush's initiative essentially solved the safety issues for airborne nuclear weapons. (27)

Since, according to Drell, the consequences of a plutonium explosion are roughly one hundred times worse than a plutonium fire, the addition of IHE to a weapon removes about 99 percent of the plutonium dispersal danger.  FRPs could remove part of the remaining 1 percent of the danger.  FRPs add no degree of safety if the explosive in the warhead detonates, so there is little point in adding FRPs to a weapon that does not also have IHE.  FRPs cannot reliably withstand a rocket propellant fire, which could be much hotter than a jet fuel fire (about 2000 degrees centigrade versus 1000 degrees), so there is little point in adding FRPs to ballistic missile warheads. 

So are FRPs worth the expense?  Even before President Bush took nuclear weapons off airplanes, Assistant Secretary of Energy for Defense Programs Richard Claytor told Congress that "for weapons such as the B-61 family and the W-80, which already have IHE, this [addition of FRPs] will be a very costly upgrade to accomplish a modest improvement in safety."  He added that "for tactical systems, where weapons are normally stored in bunkers, the reduction in risk may be very small." (28)

The Air Force's official response to the Drell Panel also panned the marginal benefits of FRPs.
    Qualitative assessment indicates that [the] safety risk associated with incorporating FRP into bombs and cruise missile warheads which already have ENDS and IHE would exceed the safety gain realized by FRP, [and so such weapons] should not be modified to incorporate FRP. (29)  
The Drell Panel called for an aggressive study of "super-safe" designs, such as designs in which the plutonium was physically separate from the IHE or HE.  In response, Kidder pointed out that such designs had been under study for at least 15 years (by 1991) without practical result.  Furthermore, any designs finally created would very likely be quite complex, which means that they might have serious reliability problems.  In any case they would require numerous nuclear tests.  This recommendation, like the one calling for all airborne warheads to have IHE and FRPs, was evidently not considered practical by the Nuclear Weapons Council, leading to the testimony cited previously.

Note that IHE was intentionally not incorporated into the W88 Trident D5 warhead, because IHE is less energetic and reduces the yield of the weapon, the range of the missile, and/or the number of warheads it can carry.  A conscious decision was therefore made to not make these particular weapons as safe as possible, because they were, and still are, judged to be safe enough.  In addition to the W88, IHE is also not present in the W62 and W78 Minuteman III warheads and the W76 Trident C4 warhead.  The W62 and W78 warheads are being retired, which will leave the Navy's W76s and W88s as the only warheads in the START II arsenal lacking IHE. (30)
Interestingly, an FRP-equipped cruise missile warhead (the W84, one of only three such FRP-equipped weapons in the stockpile) has been taken out of the active stockpile, in favor of cruise missile warheads that lack FRPs (specifically, the W80-0 and W80-1). (31)    Thus the Air Force, the Navy, and the Nuclear Weapons Council have, on at least three occasions if not also on others, concurred in decisions that chose warheads for the so-called "enduring" stockpile that lack some of the possible safety features that could have been incorporated.  The decisions to forego FRP- and IHE-equipped weapons contrast sharply with the rhetoric coming from the labs calling for so-called "safer" weapons.  Finally, note that incorporation of an FRP and, especially, IHE into a weapon would require a substantial redesign and would, in effect, amount to a new weapon.  Kidder suggests that roughly three nuclear tests per warhead or bomb would be necessary to proof-test the former and that six such tests would be required for the latter. (32)    Thus these are not minor changes, and they would require perhaps two dozen nuclear tests to accomplish for the entire START II stockpile.  It is certainly not accurate to call such changes "safety improvements to existing weapons," as is now commonly done.

Table 1 (attached) shows the planned U.S. stockpile and its safety features. 

D.  Dr. Drell believes that physics package safety improvements should not be undertaken

Since his 1990 work, Dr. Drell has clarified his position on the advisability of modifying nuclear weapons physics packages to increase safety. (33)   Writing with Bob Peurifoy, Drell acknowledges that some weapons in the so-called "enduring" arsenal do not have every safety feature to prevent plutonium dispersal and that some questions involving multi-point safety remain for the Trident systems.  But these deficiencies should not, in their view, lead to modification of the stockpile physics packages.  Drell and Peurifoy point out that if multipoint safety was judged to be inadequate for the Tridents, and monies were actually to be budgeted to improve them, this could be done by means other than modifying the warhead:  installation of blast shielding around the third-stage motor and decreasing the number of warheads to compensate for the weight, changing the third-stage propellant, costing about 4% in range, or omitting the third stage motor altogether and decreasing the number of warheads from eight to four to give the same range as at present. (34)

Should some "devices" -- the term used by Drell and Peurifoy for the nuclear explosives themselves -- be changed to make plutonium dispersal less likely?  They say not.
    Most importantly, in the case of a test ban, one should not tamper with the device hardware once it has been certified ... in the absence of follow-on stockpile testing, hardware modifications must be avoided ... New, untested devices should not be considered.


    From a technical point of view, safety improvements could be achieved in a continued underground testing program focused on safety.  From a political perspective, however, continued testing of nuclear weapons may hinder efforts to counter, if not prevent, the proliferation of nuclear weapons in the years ahead.


    In our view, the early achievement of a strengthened and durable worldwide nonproliferation regime will contribute more significantly to worldwide nuclear safety than will further improvements in the safety of part of the US nuclear force. (35)

Drell and Peurifoy then call for the U.S. to "take the initiative" and "lead a joint effort by the five declared nuclear powers to negotiate an end to all nuclear weapons testing" (emphasis added).  They also call for "a diverse and coordinated scientific program at the national weapons laboratories so that they can maintain and certify confidence in the US nuclear deterrent over a long period without testing." (36)   Maintaining safety is not mentioned as a challenge for that program, for reasons that will now be examined.

E.  There are no safety problems related to aging of weapons

Although authorities agree that nuclear weapons are "safe" now, often vague reference is made to possible safety problems that could arise in the future.  What these problems might be is never mentioned, however.  After all this intensive review by the Drell Panel and subsequently by the labs -- who were, it is fair to say, searching for every possible reason to continue nuclear testing and nuclear weapons design work in general -- it is difficult to imagine that some heretofore overlooked safety problem of real significance would suddenly appear. 

Likewise, no safety problems are expected to occur in the aging process.  This was the first question posed to Dr. Kidder by the senators, and he makes it clear that aging does not create safety problems. 

    Safety problems with nuclear warheads are generally inherent in the design of the warhead itself, not the result of aging or other causes.  Such problems may not be identified until long after the warhead enters stockpile, but they were there to begin with.

    Metals corrode, and organic materials such as plastics, adhesives, and HE that are present in a nuclear warhead will deteriorate with ageSuch aging effects degrade a warhead's reliability rather than its safety. The sensitivity to impact or fire of the HE used in nuclear warheads does not increase significantly with age.)

    A severe case of aging was the deterioration of the HE in the W68 Poseidon warhead, which produced a harmful, chemically reactive effluent.  This resulted in a potential loss of warhead reliability that necessitated a complete rebuild of all W68 warheads in stockpile.  The reliability, but not the safety, of the warhead was affected. (37) (emphasis added)
Dr. John Immele, Director of Los Alamos National Laboratory's (LANL's) Nuclear Weapons Technologies Program, spoke to this same point on December 8, 1994 at a public hearing in New Mexico.
      Audience:  I have one more question ... in a deleterious way, they may age or crack.  What do you mean, is there a risk to the public?

    Immele:  No, there's not a safety risk.  There's a performance problem ... because insensitive high explosive is so insensitive that sometimes if it's cracked it won't light on the other side when it's supposed to, so it's basically a performance problem.

    Audience:  A reliability problem?

    Immele:  That's right, it's a reliability issue.  We have not found aging problems that affect safety, that make the explosive more sensitive.(38) (emphasis added)
This testimony is very important, since the long-term behavior of IHE is not understood as well as that of HE, and it is sometimes mistakenly implied that this uncertainty extends to questions of safety, which it clearly does not.

The impression should not be left that once weapons are put into the stockpile they are forgotten.  The stockpile surveillance program coordinated by the laboratories, especially by Sandia, routinely inspects weapons and their components and ensures, among other goals, that safety problems do not develop.  Thus safety throughout the aging process is ensured by both the current weapons' inherent safety features and a coordinated surveillance program.

F.  DOE's proposed new facilities have nothing to do with weapons safety

As part of its proposed SBSS program, DOE is planning to build a number of new experimental weapons science facilities with a total cost running into the billions of dollars. (39)    The largest of these is the National Ignition Facility (NIF), a laser fusion machine with a currently-estimated capital cost of about $1.2 billion and a lifetime cost of about $4.5 billion. (40)   The role of NIF in the SBSS program is to simulate the implosion process that occurs in the thermonuclear "secondaries" of nuclear weapons. 

Throughout the 40-year history of the thermonuclear arsenal, no safety problems have ever been identified with secondaries, which contain neither plutonium nor high explosives.  Nor are any expected.  It is therefore patently obvious that NIF has nothing to do with nuclear weapons safety.  Dr. Steven Younger, who was at the time Deputy Program Director of the LANL Nuclear Weapons Program, was among others who made statements to this effect at a DOE-sponsored workshop on NIF on September 8, 1994 in Washington. (41)

For the same reason, other facilities for simulating secondary implosion, like ATLAS (LANL's proposed new pulsed-power implosion facility) have nothing to do with nuclear weapons safety either.  The only facilities with potential relevance for nuclear weapons safety are those being built or planned for the simulation of nuclear weapons primaries.  These are the hydrodynamic testing facilities:  the $124 million Dual-Axis Radiographic Hydrotest facility (DARHT), under construction at LANL but halted for environmental review, and the $422 million Advanced Hydrotest Facility (AHF), planned for the early years of the next century.

Hydrotest facilities cannot test either the high explosives or the plutonium pits of stockpiled weapons.  The former cannot be separated intact from the pit they embrace, and the latter cannot be tested without a nuclear explosion.  Therefore, these facilities test mock weapons assemblies.  There is very little point in conducting hydrodynamic explorations of the safety of existing weapons.  These weapons are already known to be one-point safe and their plutonium-dispersal properties are already clear -- either they have IHE and FRPs or they do not. 

The only purpose of these facilities, as far as safety is concerned, is that they can be used to design new primaries that have IHE and FRPs, either primaries for new weapons with new military characteristics or to retrofit into existing warheads and bombs.   This can be done either directly, by testing mockups of these new primaries, or indirectly, by conducting precise hydrodynamic tests on existing designs for which nuclear testing data is available ("benchmarking").   Benchmarking allows the nuclear testing database to better inform the nuclear weapons codes, which can then be used to design new weapons.

Actually, DARHT may be inadequate either to design new weapons with IHE and FRPs or to benchmark some stockpiled systems, with or without these features.
    Recognizing the importance of continued research in radiography, the Laboratory [LANL] cites DARHT as its top construction priority ... For a number of stockpile systems, particularly those that are designed with insensitive high explosives and fire-resistant pits, planned radiography upgrades [i.e. DARHT] do not provide resolution adequate to observe the gas cavity configuration of the primary stage late in the implosion process.  For effective monitoring of stockpile weapons [sic] of this type, a next-generation hydrodynamic testing capability will need to be developed.  Such an Advanced Hydrotest Facility (AHF) will include multiple beams that produce X-rays from four to six directions at various times to characterize the physical state of the pit more thoroughly. (42)
It is difficult to avoid the inference that DARHT is useful primarily to design new weapons which lack IHE and FRPs.  This is not at all unlikely from a policy point of view, given that these features have already been intentionally omitted from significant portions of the arsenal. 

Any use of these new hydrotesting facilities to examine safety problems relating to aging of weapons is moot, since logic, together with Drs. Kidder and Immele, all agree that there are no such issues.


6. Reducing the nuclear danger 

The risk to the public from a nuclear weapons accident is only one among many interrelated risks associated with nuclear weapons.  Attempts to increase safety from nuclear weapons accidents through redesigning warheads may easily create countervailing risks throughout this interconnected system.  For example, the replacement of hundreds or thousands of warheads, and especially the plutonium pits of warheads, will create risks to workers and the general public during the manufacturing process and in the management of its wastes, not to mention during the eventual decontamination of buildings and equipment that will later be required.  Any environmental contamination that occurs will require cleanup.  These considerable risks tend to be minimized or forgotten entirely by the advocates of weapons redesign.

In fact, these manufacturing, waste management, decommissioning, and cleanup risks are likely to be much greater than the risk reduction that could be achieved by the addition of, for example, IHE to W88s and W76s, to pick one modification currently under consideration.  The historical record suggests this.  While there have been no known or putative deaths due to accidents from explosions or plutonium dispersal from completed weapons -- even during the Cold War when thousands of weapons were shuttled all over the world -- numerous deaths have occurred due to ordinary occupational causes in the nuclear weapons complex as well as to chemical toxins and radioactivity. (43)   Meanwhile cleanup, which could be quite hazardous, has barely begun. (44)

Moreover, should the U.S. elect to upgrade its nuclear arsenal for the sake of "improved" safety or for any other reason, it can be expected that the other nuclear powers, particularly Russia and China but probably also Britain and France, may do likewise.  In that case, the morbidity, mortality, and environmental damage in other countries, again notably Russia and China, can be expected to be equal or greater than here. 

Thus, the quest for greater nuclear weapons "safety," if allowed to proceed within the compartmentalized thinking that characterizes the bureaucratic "stovepipes" of the federal nuclear establishment, will likely saddle current populations and future generations, here and abroad, with increased, not decreased, risk.   And, as has been the case up to now, this risk will tend to fall most heavily on the vulnerable members of society and the populations that are weakest politically.

A.  The proliferation impacts of safety "improvements" must be examined

Another component of the overall nuclear danger is nuclear proliferation.  A public opinion poll conducted by Sandia National Laboratory for DOE suggests that the public considers the risk from nuclear proliferation to be the number two danger facing us today, right behind world hunger and ahead of AIDS, drug trafficking, and global warming. (45)   Thirty-two percent of the public thought nuclear proliferation was an "extreme risk."  This opinion is matched by a widespread concern among experts that the proliferation problem, far from being under control, is a very serious threat to the security of the United States.  Assuming this is true, we can conclude that if safety improvements in nuclear weapons design incur even a small incremental risk to the world's nonproliferation regime, such "improvements" are likely to increase, not decrease, the nuclear danger.  On its face, nuclear proliferation is simply a much more serious problem than nuclear weapons safety.

It is beyond the scope of this paper to discuss in any detail the proliferation dangers inherent in upgrading the U.S. arsenal to achieve "increased" safety.  Suffice it to say that even a heuristic analysis of comparative risk must embrace the reality that such safety upgrades attempt to prevent events whose probabilities are already very low.  The probability of proliferation under current policies, however, is not low at all, and the probability of nuclear attack or threat of attack by proliferant nations or groups approaches certainty in the long run if more effective leadership on this issue is not forthcoming. 

Any analysis of the nonproliferation impacts of contemplated weapons upgrades must therefore consider every possible impact, even those which are slight.  Just as every credible nuclear weapons accident should be examined and prevented, so should every credible potential proliferation impact also be prevented.  The probability of an accidental nuclear detonation is kept at 10-9 per warhead lifetime, or roughly 10-5 for the current arsenal taken as whole over the next few decades; any decision to upgrade U.S. weapons should likewise be examined to see whether, through their impact on the nonproliferation regime, such upgrades could cause an increase in the probability of an intentional attack on the U.S. as small as 10-5 over the next few decades.  Clearly, the expected mortality from an intentional attack is much larger than that for any credible accident, further emphasizing the relative importance of proliferation risks and the efforts needed to combat it.

This spring, the Nuclear Nonproliferation Treaty (NPT) was extended indefinitely.  Despite some media claims to the contrary, this was not done by consensus but by an uncontested acknowledgement that a majority of states favored extension. (46)   This extension was won only after what the Washington Post called a "global full-court press" by the U.S.;(47)as late as January of this year, roughly one hundred countries did not support indefinite extension.(48)  The reason for the vocal and sometimes bitter debate that went on in New York was, above all else, deep international discontent with the failure of the nuclear weapon states to dismantle their nuclear arsenals pursuant to Article VI of the NPT.  Because of this failure, substantive further strengthening of the world's nonproliferation regime now appears to be temporarily out of reach. 

When even maintenance of arsenals can threaten to unravel the fragile fabric of the world's nonproliferation efforts, as it did this spring, how can upgrading that arsenal, whether for so-called "safety" improvements or any other purpose, not damage U.S. nonproliferation efforts?  The conclusion of Drell and Peurifoy is sound:  safety improvements to the nuclear components of weapons, which cannot be undertaken without underground testing, run counter to U.S. nonproliferation objectives.

Other nations may be concerned that "safety upgrades" can mask the development of entirely new weapons. There is considerable justification for that concern, as is discussed in detail by William Arkin, Greenpeace, and Tri-Valley CAREs.(49)  Foreign "safety upgrades" may also be used to mask new weapon development, an outcome with negative security implications for the United States.

B.  Fewer deployments and further retirements are virtually the only way greater overall nuclear weapons safety can be achieved

Given that upgrading and replacing nuclear weapons is likely to create serious countervailing risks -- risks which, on their face, are considerably greater than those gained from any purported safety "improvements" -- the search for greater nuclear safety must be directed elsewhere.  Clearly, all other factors being equal, the probability of a serious weapons accident is proportional to the overall size of the arsenal.  A minimum deterrent force -- however one may define "minimum" -- is also, therefore, an optimum safety arsenal.  It is a minimum cost arsenal as well.  A smaller arsenal would assist U.S. nonproliferation objectives, and would cause fewer dangers to the environment, to worker safety, and to public health.  A smaller arsenal, to the extent that it corresponds to smaller arsenals abroad and especially in Russia, reduces the number of missiles which could be targeted at the United States.

Indeed, given comparable reductions in other nations' stockpiles, it can be persuasively argued that the optimum safety arsenal is one that is extremely, if not vanishingly, small.  Many military and senior civilian defense leaders, past and present, have come to adopt this view. (50)

In addition to reducing the size of the arsenal, the movement of additional weapon systems away from active deployment and into safe bunkers would also reduce risk from accidents, as would the movement of nuclear weapons away from bases located in populous areas.  Further restrictions on the airborne transport of nuclear weapons should also be considered.

C.  Increasing safety will decrease reliability -- and hence could generate calls for nuclear testing

As we have seen, the quest for "increased" safety has a very marked cost in terms of weapons reliability.  That is, if weapons are changed to make them "safer," they will be less reliable -- unless we are able to proof-test the new designs. Resuming nuclear testing, however, would conflict strongly with nonproliferation goals and our treaty commitments.  Thus the quest for "safer" weapons, if accepted at face value, could keep the weapons labs in a booming business for a long time by eroding the reliability of the weapons.(51)

7.  Public safety, not nuclear safety, is the goal

So far we have examined nuclear weapons safety issues from a narrow technical perspective and in the broader context of reducing the nuclear danger as a whole.  From the still broader vantage point of public health and safety as a whole, further investments in safer designs for nuclear weapons have vanishingly small returns.
A.  Further investments in nuclear weapons safety have a very low benefit/cost ratio compared to other public safety investments
Would upgrading to IHE and FRPs be worth the expense?  Analysis -- not to mention common sense -- shows that investments in other government programs (e.g. highway improvements, cancer screening) yield orders of magnitude greater safety benefits to the general public. 

Steve Fetter and Frank von Hippel estimate that a worst-case accident involving explosion of the HE in ten W88 warheads at the Bangor Trident base directly upwind from Seattle would involve on the order of 1,000 plutonium-induced cancer fatalities in the long run. (52)   They suggest, for the sake of argument, that the risk of this accident can be assumed to be on the order of 0.1% per year, in which case the expected fatality rate from this type of nuclear weapon accident is 1 death per year.  The prevention of this accident by the spending of about $1 billion (Drell and Peurifoy's more recent article cites a cost of $1.6 to 1.8 billion) to equip some 3000 submarine missile warheads with IHE would represent a cost on the order of $100 million per fatality avoided. (53)    This accident has, subsequent to their paper, been made very unlikely by loading the missiles and the warheads separately, lowering the expected fatality rate by probably at least one, if not two or more, orders of magnitude and correspondingly raising the cost per fatality avoided. 

Fetter and von Hippel cite cost estimates in the range of $20,000 to $140,000 per life saved by cancer screening, $400,000 per life saved by kidney dialysis, and $30,000 to $300,000 per life saved for various highway safety improvements.  Thus the IHE warhead upgrade program, even by their highly conservative calculations, would cost on the order of 250 to 3,000 times more than these other prevention programs per life saved -- or, given the operational changes already put in place by the Navy, at least 10 to 100 times as much as this.  This great disparity of benefit -- at least 3 if not more than 5 orders of magnitude -- signals that the overall sense of their conclusion is robust with respect to large changes in their assumed accident rate.

What is more, the government and private programs cited by Fetter and von Hippel are almost certainly not the most effective ones offered by government or private sources, either in terms of average cost or marginal cost per life saved.  Programs targeted at populations at risk like the Women, Infants, and Children (WIC) program, for example, are arguably at least one order of magnitude more effective per dollar spent than highway improvements in preventing deaths.  And, on average, WIC and other perinatal programs address a younger population--one young adult and one infant -- than do the programs Fetter and von Hippel cite, giving more years of life saved per person in these cases. 

It would be interesting to compare Fetter and von Hippel's numbers to the benefits of investments in strictly military health and safety.  The military environment is a dangerous place, and large numbers of military accidents occur annually, sometimes with accompanying civilian deaths.  It is highly likely that it would be more cost-effective to use a billion defense dollars to prevent unnecessary military mortality -- through, for example, more complete training -- than it would be to use this sum to upgrade Trident missiles and their warheads, for which purpose a billion dollars would probably not be adequate in any case. 

This, of course, is a peacetime comparison.  Since, realistically, nuclear weapons are useless in actual fighting, any investment in them deprives the soldier, sailor, or airman of just that much supporting materiel or training when he or she needs it most.

B.  The quest for nuclear weapons safety is inconsistent with other federal and DOE positions, past and present

In the United States, 32.5 persons per 100,000, or approximately 81,250 people, died from "accidents and adverse effects" in 1990.  (54)   This is a very large fatality rate, much more even than a major conventional war.  In the same year (as in every other year since the beginning of the nuclear age) not one person died from the accidental explosion of a nuclear weapon or, as far as is known, from exposure to nuclear materials from a nuclear weapons accident. (55)   Actuarially speaking, nuclear weapons accidents don't even appear on the ledger. 

But what about the future?  A heuristic analysis, which can only be very crudely approximate, suggests that an estimate of risk of death due to a nuclear weapons accident is likely to be, on its face, two to three orders of magnitude below the risk factors typically used as a basis for federal environmental health standards, namely 10-5 per lifetime of exposure. (56)   This comparison is made, for all its inevitable flaws, because the weapons laboratories from time to time engage in struggles to weaken these environmental standards, notably in regard to ground and surface water quality, saying that the safety risks involved are "negligible."  Irony aside, this comparison is a prima facie indication that the public health cost of weapons safety "improvements" could easily exceed the risk reductions attainable through design changes -- even if those "improvements" caused only those population exposures which were considered safe and no accidents did not occur in production, waste management, decommissioning, and cleanup associated with the design changes.

More ironic still is the fact that the same laboratories who are even now clamoring for money to develop "safer" nuclear weapons -- this after the weight of evidence presented in the past four years and the military's lack of interest in the subject -- are exactly the ones who were saying that above-ground nuclear testing was not dangerous just a few decades ago. Federal agencies, such as the Veterans Administration and the Department of Justice, as well as many individuals at the laboratories, still deny the legacy of this testing in specific cases and in general. 

When it was convenient to do so, these institutions systematically lied to the public and to the servicemen who were intentionally exposed about the actual risks of nuclear testing.  Even today they continue to withhold extensive information about measured fallout distributions. (57)   Unlike nuclear weapons accidents, which, as far as we know, have been the cause of no casualties, the casualties of this intentional program were immense.  A special team convened by the International Physicians for the Prevention of Nuclear War calculated the expected mortality from fallout worldwide to be 430,000 deaths by the turn of the century. (58)   Frank von Hippel's update of Sakharov's 1958 estimates of mortality from above-ground testing suggest that the long-term death toll will be in the neighborhood of 5 million persons. (59)   Against this background, the call for "safer" nuclear weapons rings very hollow indeed.

8.  Conclusion 

We have seen how fears about the "safety" of nuclear weapons have been rhetorically advanced by the weapons laboratories and the DOE with little regard to these simple facts:

  • current U.S. nuclear weapons have the benefit of fifty years of technical improvements in safety, and further design improvements can bring only marginal and diminishing returns in actual risk reduction at a very large dollar cost;

  • upgrading the arsenal for the sake of safety will create countervailing risks throughout the complex and the world;

  • upgrading the arsenal could have enormous nonproliferation impacts; and

  • much more cost-effective and elegant non-technical solutions to decreasing risk are available -- such as retirements, further reductions in arsenal size, and changes in deployment and transportation. 
It is as if the Department were simply pandering to images of doom in order to generate political capital for its science-based stewardship program, which actually has very little to do with safety.  The Department as a whole is unreasonably tolerant of the stark contrast between its own very public promotional rhetoric and that of its contractors regarding the "safety" issue, on the one hand, and its joint testimony with the DOD to Congress, on the other, which essentially lays the issue to rest.

From a broader perspective, the nuclear weapons "safety" debate has lost its sense of proportion because it has focused on the safety of the weapons, rather than on the safety of people.  In this all-too convenient process of linguistic contraction, weapons are made the primary reference reality, not the public.  These distortions have occurred because the pitch from the labs and the DOE is actually not motivated by safety, but by a desire for a less-conflicted weapons ideology, especially for the younger scientists, and for perpetual funding.  It is this funding that would be made safer.  Nothing else can explain the irrationality of the open-ended quest for so-called "safer" nuclear weapons.



1.  Testimony of Deputy Secretary of Defense John Deutch before the House Foreign Affairs Committee, October 5, 1994:  "...advanced permissive action devices, so-called coded control devices, will be introduced into the B-52, the Minuteman IIIs, and eventually into the Trident force as well." 

The draft "Stockpile Stewardship Program Plan for Fiscal Years 1995 through 1997," prepared for the Interagency Working Group on February 27, 1995, makes it clear that permissive action links are the subject of active research, development, and replacement in several, if not many or all, weapons in the stockpile. 

2.  Sidney Drell, John Foster, and Charles Townes, "Report of the Panel on Nuclear Weapons Safety," House Armed Services Committee, December 1990. 

3.  Testimony before the House Appropriations Committee, Subcommittee on Energy and Water Development, Energy and Water Development Appropriations for 1995, Part 6, pp. 413-414. 

4.  Ibid, p. 419. 

5.  Quoted in Tom Zamora-Collina, "New Jobs for Old Labs," Bull. Atomic Scientists, November 1992, p. 16. 

6.  Quoted in Frank von Hippel and Tom Zamora-Collina, "Testing, Testing, 1, 2, 3 -- Forever," Bulletin of the Atomic Scientists, July/August 1993, p. 28-32.  Deutch went on to say, "...there are operational steps that one can take to...ameliorate the safety problems when you mate the warheads to the missiles that are being looked into, but I would not think this an immediate problem..." 

7.  Testimony before the Senate Subcommittee on Nuclear Deterrence, Arms Control, and Defense Intelligence, cited by von Hippel and Zamora-Collina. 

8.  Sidney Drell, John Foster, and Charles Townes, Report of the Panel on Nuclear Weapons Safety, House Armed Services Committee, December 1990. 

9.  The most authoritative and detailed review of these issues in the open literature is still that of senior Livermore weapons physicist Ray Kidder, who was requested to provide an independent analysis of the safety question by several members of the U.S. Senate.  See Kidder, "Report to Congress:  Assessment of the Safety of U.S. Nuclear Weapons and Related Nuclear Test Requirements," July 26, 1991, UCRL-107454, and also his "Post- Bush Initiative Update" of the same paper in December of 1991, UCRL-109503.  His thorough investigation followed, and built upon, that of the Drell Panel and incorporates relevant portions of their work in summary fashion. 

10.  Public safety is only one of the goals of government, and so this hierarchy of goals is really just one component of a larger picture.  While this outline is an oversimplification, the primary roles and risks of nuclear weapons are all included here.  Some believe that nuclear weapons have a role in extended deterrence, i.e. in protecting against conventional attack against U.S. forces on foreign soil or against non-nuclear weapons of mass destruction.  Others, such as the present writer, believe that nuclear deterrence in any form is counterproductive and illegal in the long run, if not also in the short run.  These issues are beyond the scope of this paper. 

11.  This slogan has been in frequent use in the nuclear weapons community since at least 1993.  It is the integrating principle of the draft DOE National Security Strategic Plan, dated November 3, 1993. Reducing the Nuclear Danger:  The Road Away From the Brink is the title of a book by McGeorge Bundy, William Crowe, and Sidney Drell (Council on Foreign Relations, 1993). 

12.  These safety concerns are reflected in the military characteristics (MCs) required by the Pentagon during the weapon design process.  Those requirements include, in order of priority, nuclear safety, size and weight, plutonium dispersal safety, operational reliability, yield, conservative use of nuclear materials, and operational simplicity.  In the event of a conflict between design priorities, nuclear safety is the highest priority.  See George H. Miller, Paul S. Brown, and Carol T. Alonso, "Report to Congress on Stockpile Reliability, Weapon Remanufacture, and the Role of Nuclear Testing," 1987, UCRL-53822. 

Interestingly, this official paper, in its exhaustive review of all the reasons to continue nuclear testing, does not mention any unresolved safety issues with then-current warheads or bombs.  It was only in the early 1990s that safety issues gained prominence, first during the nuclear testing debate, and now as a challenge for science-based stockpile stewardship. 

13.  Drell, Foster, and Townes, pp. 25-26. 

14.  These weapons are the 9-megaton B53-1 gravity bomb (which has only one electrical safety system rather than two independent ones) and the W62 Minuteman III warhead; see Christopher Paine, "CTB Negotiating Issues with Implications for Nuclear Nonproliferation," Natural Resources Defense Council, 1994, and Stan Norris and Bill Arkin, "Nuclear Notebook," Bulletin of Atomic Scientists January/February 1995, pp. 69-71. 

15.  Drell, Foster, and Townes, p. 13. 

16.  More recently, "multi-point" safety has also been made an objective.  The discussion which follows includes both one- and multi-point safety concerns. 

17.  Mechanical safing, which has been available and in successful use for more than two decades, can virtually eliminate the possibility of an unintended nuclear explosion, even if many points of the HE or IHE are detonated at once.  According to Frank von Hippel, mechanical safing can be added to a nuclear warhead without nuclear testing. See von Hippel, testimony to the Senate Foreign Relations Committee, July 23, 1992. 

18.  Drell, Foster, and Townes, p. 25.  The only place these analyses could have been done, given the classification barriers, the specialized codes, and the data requirements, was the weapons labs.  It is quite likely that at least preliminary analyses of this type had already been done when the Drell Panel began its work.  Indeed, at least part of the impetus for the Drell Panel was testimony offered by the three weapons lab directors before the Senate Armed Services Committee in May, 1990, which all but said that the Short-Range Attack Missile-A (SRAM-A) was too dangerous to deploy in peacetime (see Drell, p. 40). 

19.  "It is not sufficient to pull such weapons off the alert ALFA force but retain them in the war reserve stockpile in view of the hazards they will present under conditions of great stress..." Ibid, p. 32. 

20.  Ibid, p. 29. 

21.  The Drell Panel estimates that a Pu fire or deflagration would contaminate about one square kilometer, while an explosion "could" contaminate an area of "roughly" one hundred square kilometers. Ibid, p. 30. 

22.  Frank von Hippel and Steve Fetter, "Worse than Chernobyl?" Arms Control Today, September 1992, p. 13. Descriptions of these accidents can be found in Chuck Hansen, U.S. Nuclear Weapons:  The Secret History, Orion Books, 1988 or in the Congressional Record, August 3, 1992, pp. S11172-5. 

23.  A third such accident may have occurred at Dyess AFB in Texas in 1958.  See note 54. 

24.  Vanadium has been used; see Miller, Brown, and Alonso, op. cit.

25.  von Hippel and Fetter, op. cit.

26.  J. Carson Mark, "Do We Need Nuclear Testing?", Arms Control Today, November 1990, pp. 12-17. 

27.  See Kidder's December 1991 update, cited above, for the text of the President's announcement.  Kidder notes this announcement did not go quite as far as to completely eliminate the air transport of nuclear weapons in peacetime, but points out that such transport "could be reasonably terminated after the mandated return of overseas nuclear weapons has been completed..." (p. 3). 

28.  Cited by Ray Kidder in "How Much More Nuclear Testing Do We Need?," Arms Control Today, pp. 11-14.  Claytor spoke before the House Armed Services Committee, DOE Defense Nuclear Facilities Panel, February 20, 1991. 

29.  Air Force Response to the Drell Panel, Nuclear Weapons Council Standing Committee briefing, Lieutenant Colonel John R. Curry, Secretary of the Air Force/Assistant Secretary, Acquisition, August 1, 1991; cited by Kidder, 1992. 

30.  Norris and Arkin, op. cit., and Paine, op. cit.

31.  Ibid. 

32.  Kidder, July 1991, pp. 8-9. 

33.  Sidney Drell and Bob Peurifoy, "Technical Issues of a Nuclear Test Ban," Annual Review of Nuclear and Particle Science, 1994, pp. 285-327. 

34.  Ibid, p. 313. 

35.  Ibid, pp. 321, 325, and 326. 

36.  Ibid, both quotes are from p. 326. 

37.  Ibid, p. 6. 

38.  Colloquy at public environmental impact scoping hearing regarding the Dual-Axis Radiographic Hydrotest Facility (DARHT), December 8, 1994, in Santa Fe; transcript available from DOE Albuquerque or LANL. 

39.  Tom Zamora-Collina and Ray E. Kidder, "Shopping Spree Softens Test Ban Sorrows," Bulletin of the Atomic Scientists, July/August 1994, pp. 23-29. 

40.  See DOE FY 1996 Congressional Budget Request, Project Data Sheets, Vol. 1, p. 332.  The total cost cited is the sum of capital and annual operating costs. 

41.  Personal communication at LANL site-wide environmental impact statement hearing, Santa Fe, fall 1994. 

42.  Los Alamos National Laboratory, Institutional Plan FY1995-FY2000, p. 43.
43.  A 900-page report on this subject is due from the International Physicians for the Prevention of Nuclear War in July of 1995, entitled A Global Guidebook to Nuclear Weapons Production and Its Health and Environmental Effects, MIT Press, Cambridge. 

44.  See Office of Technology Assessment, Hazards Ahead: Managing Cleanup Worker Health and Safety at the Nuclear Weapons Complex, OTA-BP-O-85, February 1993. 

45.  Released by Sandia on June 24, 1994. 

46.  "Beyond the NPT:  `Abolition 2000!'" A special report of the Western States Legal Foundation, June 14, 1995, Oakland. 

47.  Washington Post, May 14, 1995.  48.  "Atom Arms Pact Runs Into A Snag," New York Times, January 26, 1995, p. 1. 

49.  See "Changing Targets: Nuclear Doctrine from the Cold War to the Third World," Hans Kristensen and Joshua Handler, Greenpeace International, January 1995; "Nuclear Agnosticism When Real Values Are Needed: Nuclear Policy in the Clinton Administration," William Arkin, Federation of American Scientists. The potential proliferation impacts of the DOE's "science-based stockpile stewardship" program, and DOE's design program for new nuclear weapons, will be analyzed in forthcoming papers from Tri-Valley CAREs. 

50.  General Horner, former head of the Air Force Space Command and leader of the air war against Iraq, is one ("U.S. Should Trash Nukes, Top Air Force General Says," Albuquerque Journal, July 16, 1994).  General Andrew Goodpaster, former NATO commander, is another ("Tighter Limits on Nuclear Arms:  Issues and Opportunities for a New Era," and "Further Reins on Nuclear Arms:  Next Steps for the Major Nuclear Powers," The Atlantic Council of the United States, 1992 and 1993 respectively).  The views of Les Aspin, recent Secretary of Defense, are likewise well-known.

Even some weapon designers are beginning to agree.  Tom Thompson, dean of current designers at Livermore, admits, "I can't think of any target for anything in our stockpile" ("Science Comes in from the Cold," Los Angeles Times, 12/22/94). 

51.  Dr. Steven Younger, Deputy Program Director for Nuclear Weapons Technology at Los Alamos, admitted to the writer that these arguments were "defensible."  He concluded, for these reasons as well as reliability concerns, that "we should not open up existing weapons [to changes] unless it is absolutely necessary" (personal communication after Los Alamos Study Group panel discussion in Los Alamos, July 18, 1994). 

52.  Steve Fetter and Frank von Hippel, The Hazard from Plutonium Dispersal by Nuclear-Warhead Accidents, Science & Global Security, Volume 2, 1990. 

53.  Norris and Arkin estimate that the total number of W76s which will remain after START II is 1328, and that of W88s 400, making 1728 submarine-launched warheads without IHE after START II, slightly more than half the number von Hippel and Fetter used in 1990. 

54.  Statistical Abstract of the United States, U.S. Governmental Printing Office.  The accidental death rate has declined some 40 percent over the last two decades, reflecting the effectiveness of societal investments in safety like the highway improvements cited by Fetter and von Hippel.  These investments, which compete for funding with nuclear weapons, have apparently prevented tens of thousands of deaths annually. 

55.  The unclassified record summarized by Chuck Hansen in his U.S. Nuclear Weapons:  The Secret History shows what appear to be nine nuclear weapon accidents involving release of nuclear materials from weapons.  The official summaries of each event do not mention which, or how much, nuclear materials were released.  A tenth such accident, cited by Drell and Peurifoy in their Table 1, involved the detonation of a bomb at Kirtland AFB in 1957; that bomb did not have its plutonium pit installed when it was inadvertently dropped from the airplane.  Declassification of nuclear weapons accidents is not complete, however, and it is possible that further accidents have occurred. 

It is likely that cleanup crews were exposed to plutonium at some of these accident sites. The accidents at Palomares, Spain (January 17, 1966), and at Thule, Greenland (January 21, 1968), as well as possibly at Dyess AFB, Texas (November 4, 1958) involved detonations of HE with resultant nuclear contamination; these accidents appear to be the ones generating the most difficult cleanup problems and the greatest likelihood of long-term residual contamination.  I am not aware of any study of morbidity or mortality of the workers who cleaned up after these or any other accidents.  The cleanup crews, together with any undocumented population exposures (at the time of the accident or in the long run), represent the primary uncertainties in the claim that no one is known to have been injured from the specifically nuclear aspect of U.S. nuclear weapons accidents. 

56.  These order-of-magnitude estimates are included here, for all their uncertainty, because it has been observed that rational thought often breaks down when nuclear weapons safety is discussed.  This occurs even, or perhaps especially, at the top-most levels of the DOE. With the image of the mushroom cloud foremost in our minds -- particularly in the minds of those who are responsible for nuclear weapons -- no amount of funding for safety improvements seems too much.  That, of course, is because they have not been asked to choose between their own programs and other societal means of reducing morbidity and early mortality.  It may also be because safety as a goal is psychologically compensatory for those who participate in threatening other nations with weapons of mass destruction, which is, after all, what nuclear deterrence is all about.

These estimates suffer not only from attempting to quantify what cannot be quantified, but also from the implicit error of assuming that the risks of low-probability, catastrophic events are comparable to high-probability, less-severe events.  An accidental nuclear explosion, or even a plutonium accident, would arguably have a qualitatively much more severe long-term effect on a society than a comparable number of automobile fatalities.  From 1950-1980, the rate of "Broken Arrow" accidents was approximately one per year. Current safety standards require that a warhead or bomb be able to endure such accidents with a 10-6 or less chance of nuclear detonation.  Applying the 1950-1980 rate of serious accidents to the deployed START II arsenal, the probability of roughly 4,000 total weapons experiencing one accidental detonation per year with some nuclear yield greater than 4 pounds of TNT-equivalent is less than 4 X 10-3.  The current accident rate is much smaller than the historical rate, however, since (a) there are to be fewer deployed weapons than the height of the Cold War, (b) these weapons are now flown around on airplanes much less frequently than in 1950-1980, (c) dangerous exercises like airborne refueling are surely no longer conducted with live nuclear weapons, and (d) these weapons are not kept on alert aircraft parked on runways.  These four factors, taken together, probably reduce the rate of "Broken Arrow" accidents by a factor of about 100. Our order-of-magnitude estimate of the current accident rate might therefore be about 10-2 per year, and of accidental nuclear explosion about 4 X 10-5.

Most nuclear weapons are stored and transported away from urban areas, so the probability of an accidental explosion in a city is quite small.  The size of an accidental nuclear explosion could, by definition, be anywhere between 4 pounds TNT-equivalent and about 1.2 megatons (see Table 1).  Perhaps 105 people is a reasonable upper bound for the number that would be likely to die from an accidental explosion; that is approximately the number of fatalities that occurred when the center of a city largely made of light buildings -- Hiroshima -- was bombed.  In other words, we might expect, in very round numbers, a reasonable upper bound of 4 deaths per year from a nuclear weapon explosion, with an expected number of deaths per year perhaps two orders of magnitude below this, or 0.04 deaths per year. 

This compares with the worst-case scenario drawn up by Fetter and von Hippel for a plutonium dispersal accident, for which the corresponding number was 1 death per year.  The probability of the particular accident scenario which Fetter and von Hippel analyzed has been greatly reduced if not virtually eliminated, however, by the simple expedient of separating warheads from rocket motors during loading.  The possibility of a plutonium-dispersing accident elsewhere than the Trident docks has not entirely vanished, of course, despite the fact that all of these non-Trident weapons have IHE and some of them have FRPs as well (see Table 1).  Assume, arguendo, that these changes have reduced the expected annual deaths by a factor of 10 to 100, i.e. to about 0.01 to 0.1.

It seems therefore plausible that the a priori expected number of annual deaths from a nuclear weapons accident is on the order of 0.1 or fewer persons/year, or roughly one million times less than the expected number of deaths from other accidents.   The probability of dying in any accident is, in turn, about 50 times less than dying of a disease, which is about 0.98. Our rough estimate of the probability of any given person in the U.S. dying from a nuclear weapons accident in a given year is thus about 4 X 10-10 or less, or less than 3 X 10-8 in a 75-year lifetime.  These numbers are very low, and errors in them of up to three orders of magnitude will not affect the conclusions which follow in the text. 

57.  See Stewart Udall, The Myths of August:  A Personal Exploration of Our Tragic Cold War Affair with the Atom, Pantheon, 1994.  Dr. Hugh DeWitt of Lawrence Livermore has recently drawn attention to the continued classification of historic fallout data and called for U.S./Russian bilateral release of this data. 

58.  Radioactive Heaven and Earth, Apex Press, 1991, available from the Institute for Energy and Environmental Research, Takoma Park, Md. 

59.  Andrei Sakharov, "Radioactive Carbon from Nuclear Explosions and Nonthreshold Biological Effects," 1958, reprinted with Appendix by Frank von Hippel in Science and Global Security, 1990, V. 1, pp. 175-187.

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