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

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
LPF
Leakpath Factor, the cumulative fraction of airborne material that escapes to the atmosphere
from the postulated accident.
The quantity MAR is calculated as the quantity (CI * CD), where CI is the waste canister or waste drum
radiological or non-radiological inventory, CD is the number of canisters or waste drums damaged by the
accident phenomenon (number of canisters or drums breached).
The resulting equation is:
Q = CI * CD * DR * ARF * RF * LPF (5-1)
Each of the source term variables are a function of the accident phenomenon under consideration and are
derived in the following discussions. The level of conservatism in each of the safety analysis variables is
consistent with DOE-STD-3009-94 1 and its Appendix A.
Waste Container Radiological and Non-radiological Inventories (CI) and Containers Damaged (CD)
The source term equation radiological CI used in the accident analyses, is based on the waste
characterization analyses in Section 5.1.2. As described in Section 5.1.2.1, the maximum 72-B canister
radionuclide inventory that is not solidified, vitrified, or overpacked is 80 PE-Ci for direct loaded waste
and 240 PE-Ci for double contained or overpacked waste. Since one 72-B waste canister is processed at
a time, CD = 1 for all 72-B accident scenarios. The maximum 10-160B cask radionuclide inventory is 20
PE-Ci. The 10-160B cask can contain up to ten waste drums. As a conservative assumption, it is
assumed that all of the radionuclide inventory from a single 10-160B cask is located in a single waste
drum from that cask. Additionally, the RCRA permit application for WIPP allows the storage of up to
six fully loaded facility canisters (each containing three waste drums) with possibly one of them partially
loaded (1 or 2 drums) in the Hot Cell during processing of 10-160B casks. It is possible that the
radionuclide inventory from two 10-160B casks (40 PE-Ci) may be at risk in accident scenarios that
occur in the Hot Cell. It is also possible, but extremely unlikely that the three drums in a facility canister
each contains the maximum radiological contents of a 10-160B cask. Therefore, the bounding activity in
a single facility canister is considered to be 60 PE-Ci. For the accident analysis, the CI is set to 20 PE-Ci
and the CD is determined on a scenario-specific basis ( CD = 1 or 2 for drum events or CD= 3 for facility
canister events) based on whether or not more than one waste drum may be at risk in the specific accident
scenario being analyzed.
The three types of accident scenarios identified for quantitative analysis: (1) potential fires that can
compromise the containment integrity of the waste drums and/or canisters, (2) potential explosion that
can cause a breach of the waste drums and/or canisters, and (3) waste drum and/or canister breaches from
drops or waste handling equipment impacts. The waste forms defined in the Baseline Inventory Report 5
(BIR) were examined to determine the types most susceptible to these scenarios. For waste drum and/or
canister fire scenarios, combustible waste is defined as consisting of paper, kimwipes, and cloth (dry and
damp); various plastics such as polyethylene and polyvinyl chloride; wood; and filters contaminated with
trace quantities of halogenated organic solvents; and non-combustibles as sludges, filters, asphalt, soil,
glass, metal, and others.
Therefore, it is conservatively assumed that during potential fire, a waste drum and/or canister could
contain waste with a 95 percent combustible and 5 percent non-combustible content. Since the fire is
assumed to impact a single 72-B waste canister (CD=1), the CI for the fire scenarios is 80 PE-Ci for
direct loaded waste and 240 PE-Ci for double confined waste. For the 10-160B fire scenarios, NC1 and
NC2, the CDs are determined in the accident analyses.
5.2-4 January 22, 2003