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"Forget the Rest" blog


For Immediate Release January 13, 1999

Greg Mello

"Subcritical" Nuclear Tests Have Apparently Begun at Los Alamos


Santa Fe -- The Defense Nuclear Facilities Safety Board (DNFSB) has raised safety questions regarding the start-up of a series of "subcritical" nuclear test explosions at Los Alamos National Laboratory (LANL).  These "test-site-in-a-bottle" explosions test the nuclear components of nuclear weapons, but stop short of a actual nuclear explosion.  The explosions will eventually involve plutonium in a full-scale nuclear weapons configuration, in whole or in part, if they have not already done so.

Up to now, these types of tests have usually been conducted deep underground in Nevada -- amid a chorus of domestic and international protest.  The most recent Nevada test, code-named "Cimarron," involved simultaneous implosion of two halves of a full-scale, newly-manufactured plutonium "pit" from Los Alamos.  Today's revelation is the first indication that the long-planned series of above-ground subcritical tests at LANL has apparently already begun, complementing the controversial and expensive tests in Nevada.

Los Alamos has conducted subcritical experiments in the past, both underground (1) and in vessels (an unknown number, at unknown times).  The series of underground experiments left a permanent legacy of approximately 90 pounds of plutonium about 100 feet deep at LANL.

The top-secret program that is apparently now starting up again, code-named "Appaloosa," uses either weapons-grade plutonium (primarily Pu-239), with configurations modified as necessary to prevent a nuclear explosion, or the rare isotope Pu-242, code-named "Cider," which can be used to make exact replicas of weapons prototypes for high-fidelity development tests.  New development work may be interspersed (and masked for public relations purposes) with so-called "aging" studies. Proof tests of newly-manufactured pits may also be done.

Since the safety of existing designs is an intrinsic property of the design and has already been certified, any so-called "safety" studies will refer to the safety of new designs.

The history of the Appaloosa program and its predecessors is shrouded in secrecy.  It is not known how many explosions have been conducted, what the size of the explosions has been, how many of those explosions involved the special Pu-242 isotope, or what the purposes of the experiments have been.  We believe the program was idle but for one test during the 1982-1992 period.

The Study Group has photographs of vessels used in the historic Appaloosa program, as well as working drawings of the some of the vessels to be used in the current program, vessel specifications, invoices, and related documents.  In 1970, an internal safety study suggested that the need for the experiments had been "reevaluated" in light of the potential for widespread contamination and radiation exposure that could result in the event of catastrophic vessel failure.

In addition to subcritical tests at Nevada and Los Alamos, additional dynamic studies of shocked plutonium have recently begun at LANL's Materials Science Laboratory.  These are the so-called plutonium "mini-flyer" experiments, where lasers are used to accelerate metal plates that strike plutonium at high speeds.  These experiments can be conducted on a one-day turnaround basis, giving very rapid data acquisition.

Dynamic experiments are also done at LANL's main plutonium facility, which houses a high-speed plutonium "gas gun" for dynamic measurements.

These four categories of dynamic experiments, together with a wide battery of static laboratory tests, comprise a highly advanced and redundant suite of techniques that go far beyond those required to maintain existing nuclear weapons.

DOE has refused to answer questions from the Study Group about the DNFSB concerns, and would not even identify the nature of the program that was raising these concerns. All documents were stamped "Secret--Restricted Data," except for a cover letter, dated November 17, 1998, from DNFSB Chairman John Conway to DOE that was posted on the DNFSB web site.

The response from Dr. Victor Reis, dated December 17, 1998, was likewise classified except for its cover letter. It was obtained by the Freedom of Information Act from DNFSB.

The Study Group has modelled the impact of an accident from these experiments, using a standard plume model written at Lawrence Livermore National Laboratory (LLNL).  DOE and LANL used a similar model in their, partially classified, study, with similar results.  DOE subsequently did more detailed modelling, which suggested that the impacts of an accident could be somewhat more severe.

According to documents obtained by the Study Group from DOE, LANL has a 2003 deadline for certification of a new warhead for the Navy's Trident D-5 (Trident II) ballistic missile.  LLNL is also designing a warhead for this missile, using existing plutonium "pits."  LANL's design would require a manufacturing campaign for thousands of new pits.  LANL is now the only site where this manufacturing could take place, but DOE has, if its internal documents can be believed, indefinitely delayed its earlier commitment to a 50-pit-per-year manufacturing capacity at LANL.  Full pit manufacturing would, under DOE's current plans, apparently take place at "another site."

1.  Thirty-five "hydronuclear" tests, most of which involved subcritical assemblies (i.e. assemblies which were designed to avoid a self-sustaining nuclear reaction) were conducted between 1958 and 1961.   (Back to Text)

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