DOE 2000. - Waste Isolation Pilot Plant - U.S. Department of Energy

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
NC3-C, (hazardous events 10B-1) LOC in the WHB (dropped drum or canister in Hot Cell)
NC3-F, (hazardous events 12E-2, 12E-4 and 14B-1) LOC in the WHB (puncture of drum or
canister outside Hot Cell)
NC3-G, LOC in the WHB (puncture of 10-160B cask in RH Bay)
NC3-H, LOC in the WHB (dropped 10-160B cask in RH Bay)
NC4, LOC in the Transfer Cell or Underground (waste hoist failure and Transfer Cell)(same as
and bounded by RH3 and RH4-A)
NC6, Fire followed by explosion in the Underground (same as and bounded by RH5)
Releases of hazardous material as the result of accidents NC2 and NC6 were found to be incredible for
10-160B cask processing as long as the inputs and assumptions determined to be applicable to these
events in the 72B RH accident analysis are maintained for the 10-160B cask processing. Releases of
hazardous material as the result of accident NC8 were found to be incredible for 10-160B cask processing
as long as the inputs and assumptions listed in Section 5.3 are maintained.
For all accidents, the quantitative frequency analysis has verified that the qualitative frequency ranges
assigned for these scenarios in the HAZOP were either correctly or conservatively assigned.
Additional quantitative frequency analyses in the form of event/fault tree analyses were performed to
identify SSCs, or processes that contribute most to the accident phenomena frequency for the purposes of
verifying their adequacy or identifying improvements to reduce the accident frequency and therefore risk
to immediate workers (as well as noninvolved worker and MEI). Specific accidents evaluated in this
manner were: RH3, RH4A, RH4B, RH6, RH7, NC1, NC3 (A-G), and NC5. With the exceptions of
RH4B, RH6, NC1, and NC3(A - F), the event tree/fault tree analyses indicated that the
no-mitigation frequency of the identified accidents occurring are beyond extremely unlikely (frequency #
1E-06/yr).
Accident Analysis Consequence Results
Based on the 72-B cask RH accident source term and release mechanism analyses presented in Section
5.2.3, for worst-case scenarios with a frequency greater than 1E-06/yr, the calculated worst-case
no-mitigation accident consequences to the noninvolved worker and MEI, were found to be well below
the selected accident risk evaluation guidelines for the unlikely range and for the immediate worker
below the guidelines for the extremely unlikely range. The highest consequences are obtained from
RH4-B (Table E-8 of Appendix E), with an estimated 0.6 rem (6 mSv) to the noninvolved worker
(approximately 2 percent of 25 rem (250 mSv) guideline), 0.05 rem (.5 mSv) to the MEI (approximately
0.7 percent of 6.5 rem (65 mSv) guideline), and (Table E-14 of Appendix E) 5.4 rem (54 mSv),
(approximately 5 percent of 100 rem (1 Sv) guideline) to the immediate worker.
Based on the 10-160B cask processing accident source term and release mechanism analyses presented in
Section 5.2.3, for worst-case scenarios with a frequency greater than 1E-06/yr and for which the release
of hazardous material was credible, the calculated worst-case no-mitigation accident consequences to the
noninvolved worker and MEI, and immediate worker were found to be well below the selected accident
risk evaluation guidelines for the appropriate frequency range. The highest consequences are obtained
from NC1 (Table E-19 of Appendix E), with an estimated 8.2 rem (82 mSv) to the noninvolved worker
(approximately 8 percent of the 100 rem (1 Sv) guideline) and 0.65 rem
5.2-74 January 22, 2003