Re: pstd/Mobile Chernobyl

[RuthWeiner@AOL.COM]

Yes.   I have already done part of it.  The calculation of accidental releases is part of the background of the Yucca Mountain EIS.  It is also in NUREG/CR-6672, for which I believe i gave a web site.


The actual Chernobyl calculation requires a criticality calculation.  However, the releases can readily be compared.


In fact, for starters, the worst-case accidental release, using the Cs content of 32.24 MWd/MTHM burnup, 3% enriched PWR SNF, 27 years decayed,  is


3.1E4curies per assembly

4 assemblies per truck cask = 1.24E5 curies per cask

24 assemblies per rail cask = 7.44 E5 curies per rail cask 

3.6E-5 = worst case release fraction for Cs, from NUREG/CR-6672, pp 73-76, Table 7-31.  This worst case has a conditional probability (conditional on an accident happening) of 1.1E-7


3.6E-5*1.24E5 = 5.04 curies from a truck cask accident

3.6E-5*7.44E5 = 26.8 curies from a rail accident


For the case with the largest conditional probability (4.9E-5 -- the only case with P> 1E-6 - the EPA "credibility limit", the Cs release fraction  would be 1.7E-5. so the releases would be:


truck: 2.38 Ci

rail: 12.7 Ci


The crud release fraction is larger than the Cs release fraction, but the crud activity is about 1/200 of the Cs activity.  


The Kr-85 release would be much larger:

3.13E3 Ci from a truck cask

1.87E4 Ci from a rail cask


I did not include other radionuclides because the release fractions are order of magnitude 1E-8 rather than 1E-5, and only Sr-90 and Pu-241 have comparable activities in PWR SNF.  The SNF data is from the Yucca Mountain DEIS Appendix A.



Ruth Weiner, Ph. D.

ruthweiner@aol.com