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

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
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If the hoist system is to be operated more than one shift per day, or there is a change of
operator, the hoist system will be removed from service and the same "pre-operational check"
test will be performed.
Based on the service life verification tests, the failure of the brake caliper unit is not considered
Assumed that the system is structurally designed for thermal stresses/shocks
Assumed that the ambient temperature is not below the freezing point of water
Source Term Development - No source term is developed for event 8-4 because this event is prevented by
passive design features.
Event 8-6 postulates a drop of waste hoist to the bottom of the shaft during transfer of the RH waste
canister to the Underground. This scenario could result in compromising the containment integrity of the
waste canister and the facility cask.
Radiological Waste Canister Inventory (CI) - Based on the postulated scenario, the CI for this accident
has been determined to be the inventory contained in one waste canister. As discussed in Section 5.2.1.1,
it is assumed that the 72B waste canister contains the maximum radionuclide inventory of 80 PE-Ci for
direct loaded waste and 240 PE-Ci for double contained waste. The waste canister is conservatively
assumed to contain 95 percent noncombustible and five percent combustible material as discussed in
Section 5.2.1.1.
Non-radiological Waste Canister Inventory (CI) - As discussed in Section 5.2.1.1, the non-radiological
CI development process for events which involve a breach of a waste canister is simplified by assuming
that 100 percent of the VOC headspace inventory is released instantaneously. VOCs selected for
consideration for accidental releases are listed in Table 5.1-2. The weighted average of VOCs in the RH
waste is assumed to be the same as in CH waste. The mass of VOC is based on the moles of gas present
in the RH waste canister. A void space of 70 percent, same as in CH waste drums, is used for calculating
moles of gas present in the RH waste canister.
Damage Ratio - It is assumed that the RH waste is directly loaded into the RH canister, and the canister
is being transported to the underground within the facility cask when the accident occurs. As a result of
the accident, the canister and facility cask will be most likely moderately damaged. The bounding
damage ratio for a 55-gallon drum involved in the CH waste hoist accident is 0.25 from DOE/WIPP-95-
2065, WIPP Contact Handled (CH) Waste Safety Analysis Report. 6 When comparing the structural
integrity of the RH canister to that of the CH drum, the RH canister is more robust, therefore a DR of
0.25 is conservatively assigned for this RH accident scenario.
DOE/WIPP-95-2065 6 "overpack" scenarios assume that 55-gal drums are overpacked within a standard
waste box (SWB). The product of the damage ratios for the 55-gal drum overpacked within a SWB, and
the SWB, is the overall DR for the "overpack" involved in drop scenarios. This method is also applied to
a 55-gal drum within an RH canister.
The RH canister will hold three 55-gal drums each containing RH waste. However, for conservatism it is
assumed that all the waste is in the bottom drum, and that drum is impacted by the accident conditions
and releases 10 percent of its contents. Therefore, assuming a conservative DR of 0.1 for drums within
the RH canister, a conservative RH-canister overpack DR would be 0.1 x 0.25 = 0.025 for the Hoist Drop
scenario.
5.2-32 January 22, 2003