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

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
Airborne Release Fraction and Respirable Fraction - As discussed in Section 5.2.1.1, the ARF for
contaminated combustible materials which are subjected to impact and breach of the waste canister is
0.001. This value represents a bounding ARF for packaged material in a canister which fails due to
impact (DOE-HDBK-3010-94, subsection 5.2.3.2). 4 The bounding RF is 0.1 (DOE-HDBK-3010-94,
subsection 5.2.3.2). 4
The ARF for contaminated noncombustible materials which are subjected to impact and breach of the
waste canister for solids that do not undergo brittle fracture is 0.001. This value represents a bounding
ARF for packaged material in a canister which fails due to impact (DOE-HDBK-3010-94, subsection
5.3.3.2.2). 4 The bounding RF is 1.0 (DOE-HDBK-3010-94, subsection 5.2.3.2). 4
Leakpath Factor - Due to the accident scenario conditions and potential damage to both the RH canister
and the facility cask, a conservative LPF from the facility cask to the underground of 1.0 is assigned.
The amount of material removed from the air due to the HEPA filters is predicted based on DF. DF have
been predicted for accident conditions in the handbook ERDA 76-21. 14 Based ERDA 76-21, the total
DF used in this analysis for both stages of filtration is 1.0E+06. The LPF is 1.0E-06 for the mitigated
case and 1.0 for the unmitigated case.
Estimated noninvolved worker and MEI Consequences and Comparison to Risk Evaluation Guidelines -
Based on the values for the source term variables as presented above, the worst-case, unmitigated MEI
and noninvolved worker consequences (see Appendix E, Tables E-4, E-5, and E-6) of the LOC in the
Underground (Waste Hoist Drop) (RH4-A) are well within the radiological and non-radiological risk
evaluation guidelines for the extremely unlikely range.
Assessment of Immediate Worker Consequences- No current risk evaluation guidelines exist for the
assessment of accident consequences to immediate workers. Therefore, in the absence of guidelines, and
for conservatism, the noninvolved worker radiological guidelines for the extremely unlikely range are
used as a reference point for the assessment of consequences to immediate workers and the evaluation of
the adequacy of the WIPP defense-in-depth features. The worst-case consequences to the immediate
worker from RH4A (Tables E-13 and E-16) exceed the risk evaluation guidelines. However, no specific
additional worker protection engineering or administrative controls beyond those already qualitatively
identified as providing defense-in-depth for the immediate worker, are needed based on the discussion
provided in Section 5.2.4.2.
Safety Structures, Systems, and Components - The brake system on the waste hoist has been designated
as Safety Significant. The following input data and assumptions are used in the accident analysis:
C
Design of the facility cask transfer car, facility cask, and waste hoist and shaft
C
C
C
C
The facility cask is in a horizontal position and positioned with the greatest moment of inertia.
It is held in place by trunions and supports to keep it from moving.
Maximum speed of the facility cask transfer car is 30 ft (9.1 m) per minute
Maintain configuration of the waste hoist on which fault tree was based (for details see
WIPP/WID-96 -2178 40 )
Maintenance program including post-maintenance functional testing- stroke testing is assumed
for all valves following a maintenance operation
5.2-33 January 22, 2003