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

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
Based on the values for the source term variables, the worst-case, unmitigated MEI and noninvolved
worker consequences (Appendix E, Tables E-1, E-2, and E-3) of the LOC in the WHB (RH3) are well
within the radiological and non-radiological risk evaluation guidelines for the extremely unlikely range.
Assessment of Immediate Worker Consequences- No immediate worker consequences are calculated for
this accident. There are no workers in the Transfer Cell where the release occurs because the operation is
done remotely.
Safety Structures, Systems, and Components - Based on the estimated worst-case unmitigated MEI and
noninvolved worker consequences and comparison to the risk evaluation guidelines, Safety Class or
Safety significant SSCs are not required. The following input data and assumptions are used in the
accident analysis:
C
Shuttle car is designed to support the drop of waste canister from facility cask into the 72B
cask. 39
C
C
C
C
C
C
Throughput of waste canisters is 208/year.
It is assumed that the facility cask loading grapple hoist is as reliable or better than the
TRUPACT Crane System.
Grapple hoist brake system is designed to engage upon loss of power, and as such, hold the load,
thus minimizing the probability of waste canister breach.
The maximum height from which the waste canister could be dropped is # 22 ft (6.7 m).
Should an accident involving a breach of a waste canister occur, the plant design permits the
immediate cessation of activity and isolation of the area where the breach occurs. Once isolation
is achieved, there is no driving force within the waste or waste handling area that could result in a
further release of the waste material.
Distance of the grapple hoist operator from the dropped waste canister is 15 ft (4.5 m).
The defense-in-depth SSCs which are applicable to this scenario, per the criteria in Chapter 3, Section
3.1.3 are assigned as follows:
C
Vented DOT Type A (or equivalent) RH canister - Primary confinement
C
C
C
C
C
C
WHB structure - Secondary confinement
WHB RH HVAC system - Secondary confinement
WHB HEPA filters - Secondary confinement
Grapple Hoist - Designed to minimize failure resulting in a dropped load
Design of 72B cask- Prevents/minimizes releases from the waste canister
Design of waste canister - Prevents/minimizes releases of waste material
Section 5.2.4.1 discusses in greater detail: (1) the evaluation of safety SSCs, and (2) the applicability of
functional and performance requirements (system evaluation) and controls (TSRs). Detailed design
descriptions for the above defense-in-depth SSCs may be found in the applicable SDDs as referenced in
Chapter 4.
5.2-29 January 22, 2003