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"Forget the Rest" blog
Commited Effective Dose Equivalent (CEDE) - Technical Background

The following two graphs show the commited effective dose equivalent (CEDE) of the radioactive plume that would be created by an unconfined plutonium explosion in Los Alamos.  The calculation is from Lawrence Livermore National Laboratory HOTSPOT 8.0 code.   HOTSPOT's calculation gives lower doses than DOE's 1997 calculation (C. M. Steele, T. L. Wald, and D. I. Chanin, Plutonium Explosive Dispersal Modeling Using the MACCS2 Computer Code, Department of Energy, Los Alamos Area Office, 5/1997.   Link is to cover page only; obtain full document from DOE.)


How these doses translate into expected fatalities
is shown in the table below.

Relationship of CEDE to Latent Cancer Fatalities (LCFs)
(How individual doses relate to the probability of fatal cancer caused by plutonium)
If the 50-year Committed Effective Dose Equivalent 
(CEDE) 
(for nonsmokers) is
then the probability of an LCF (per person exposed), i.e. the
p(LCF) 
(for nonsmokers), is
and the p(LCF) with long- term dust resuspension 
(for nonsmokers) is
and the p(LCF) with dust resuspension 
(for smokers) is
1000 rems 0.5 (50% chance of fatal cancer) 0.8 (80% chance of fatal cancer) 1 (100% chance of fatal cancer)
100 0.05 0.08 1
10 0.005 0.008 1
1 0.0005 0.0008 0.16
0.1 0.00005 0.00008 0.016
0.01 0.000005 0.000008 0.0016


All figures are for male adults outdoors undergoing light exercise.  For example, a person at TA-55/35 would receive a CEDE of 20 rems from the postulated accident and thus have a 1 % chance of a LCF.  Out of a working population of 1000 persons, roughly 10 would eventually die from the accident, assuming all were nonsmokers.

In the Los Alamos townsite, CEDEs in the neighborhood of 10 rems could be expected, resulting in a 0.5% chance of LCF per nonsmoking person; smokers, on the other hand, who were caught outdoors would be highly likely to contract a fatal cancer.  In the Las Campanas region, CEDEs around 2 rems would lead to a 0.1 % chance of a LCF, or 20% for smokers, not counting long-term dust resuspension doses, which raise these probabilities by about 60%.  In Santa Fe proper, doses nearly this high would be experienced. The graph below shows these doses in plan view.



These contours show the lifetime dose commitments delivered by the plutonium cloud to each non-smoking individual who breathes it, under standard assumptions.  A 1.26 rem prompt dose commitment (middle contour) will deliver about 2.0 rem in the long run, due to resuspension of dust (Fetter and von Hippel, 1990, "The Hazard from Plutonium Dispersal by Nuclear-Warhead Accidents," Science and Global Security, Vol.2, p. 30).  There will be about 0.001 cancer deaths for each 2 rem committed to the population by plutonium (DOE, 1995, DARHT Final EIS, Vol 1, p. H-9).  To get total expected cancer deaths, multiply lifetime dose in rems per individual by the number of individuals exposed, then divide by 2000 rems/death. 

These HOTSPOT results generally agree with DOE's results in the DARHT FEIS as well as those of Fetter and von Hippel, and were very favorably tested by Livermore Lab against experimental data from the Nevada Test Site.

The likelihood that smokers (who comprise 23 % of population, according to the 1992 Statistical Abstract of the U.S.) will contract fatal cancers from a given plutonium dose is approximately 200 times more than for nonsmokers (Gofman, 1981, Radiation and Human Health, p. 488).  The following graph shows the ground contamination (fallout) expected from the cloud.




The EPA action level for residential areas is 0.1 micro Ci/m2 (EPA, 1990, Transuranium Elements, Vol. 2, Technical Basis for Remedial Actions, p. 5-12, EPA 520/1-90-0 16).  Real properties which received greater deposition than this could have impaired utility and value for residential purposes.  Some impact on the region as a tourism, residential, and business destination could occur.  Areas of greatest deposition might have to be abandoned for residential purposes, and cleanup of highly contaminated zones for even industrial and R&D purposes would be difficult, dangerous, uncertain, and expensive.

It is approximately 3.5 km from the DARHT site to heavily-occupied Lab areas, about 5.4 km to the Los Alamos town site, and about 7.8 km to White Rock.  It is about 36 km (or 22 miles) from DARHT to the Santa Fe plaza, with Las Campanas, etc. occupying an intermediate location.

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