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

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 5
For waste drum and/or canister breach scenarios resulting from drops or impacts, the accident is
characterized by a sharp impact to the waste drum and/or canister and damage to the waste canister,
followed by an airborne release of radioactivity due to shock/vibration effects. The waste forms defined
in the BIR 5 were examined to determine the types most susceptible to waste canister breach scenarios.
Based on DOE-HDBK-3010-94, 4 non-combustible waste forms that have a hard, unyielding surface and
do not undergo brittle fracture are the most susceptible to the airborne release of radioactivity in highly
respirable form due to shock/vibration effects. Although DOE-HDBK-3010-94 4 bounding airborne
release fraction for combustible and non-combustible waste is the same (1E-03), the respirable fraction is
higher for noncombustibles (1.0) than for combustibles (0.1). Therefore, it is conservatively assumed
that the breach accident scenarios occur with waste drums and/or canisters classified as containing
non-combustible uncategorized metal waste, with a 95 percent non-combustible and 5 percent
combustible content. As discussed earlier, at most two waste drums containing the entire radionuclide
inventory from two 10-160B casks may be at risk of damage from a breach accident. Therefore, the
number of drums impacted (CD = 1 or CD = 2) is determined by the specifics of the accident scenario.
Uncategorized metal waste is chosen for drop and impact scenarios due to: (1) the relatively high waste
volume fraction (approximately 9 percent) of the total stored waste volume, and (2) the combustible and
non-combustible fractions from the definition of the waste form in the BIR 5 . Although heterogeneous
waste has the highest stored volume fraction (approximately 59 percent), based on the definitions in the
BIR, uncategorized metal waste has the highest projected volume fraction (approximately 77 percent) and
highest potential fraction of non-combustible waste fraction (95 percent), and is therefore more
conservative for use in accident analysis calculations.
Based on the data in Table A-1 of Appendix A, use of the above values for CI and combustible/noncombustible
fractions provides reasonable assurance of obtaining bounding consequences in the potential
fire, explosion, and waste drum and/or canister breach accident consequence analysis.
The non-radiological CI development process for events which involve a breach of a waste canister or
drum 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
values were scaled for estimating concentrations in the waste drum or canister based on the volume of the
container.
Solid and liquid chemical concentrations that would be expected to be within a waste drum or canister is
the same as for CH waste and are listed in Table 5.1-3. These values were scaled for estimating
concentrations in the waste canister based on bounding weight of material in a waste canister.
Radiological and chemical source terms developed for specific accidents are estimated using Equation
5-1.
For the radiological CI, the CD is limited to either 1 or 2 as discussed previously. However, for the
non-radiological inventory, all of the waste drums are assumed to contain equal inventories. Therefore,
as many as 20 waste drums could be at risk for damage and release of non-radiological hazardous
material. The CD is determined for each of the accident scenarios on the basis of the specifics for the
scenario. Note that this means that the CD for the radiological and non-radiological releases may be
different for the same accident scenario.
5.2-5 January 22, 2003