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TRUPACT I1 SWB or metal waste box; and 1,255 grams in a POC) and TypeB shipping
containers With up to 6,000 grams of WG Pu. The predominant radioactive materials that will
be found in the Building 991 Complex are isotopes of plutonium blended with some americium
rather than uranium. As shown in NSTR-011-98, the gram quantity radiological thresholds for
23% and 241Am are less than comparable uranium isotope radiological thresholds. In addition,
the radiological consequences of uranium in Type B shipping containers or waste containers is
bounded by equivalent containers of WG Pu. For the above reasons, the container inventories of
uranium isotopes are not of interest.
Since the "'Pu content of WGPu is over 92% (see SARAH, Ref. 9), the upper bound
WG Pu content of 5 TRU waste 55-gallon waste dnuns (approximately 920 grams of "'Pu),
1 POC container (approximately 1,155 grams of "'Pu), 4 TRUPACT I1 SWB containers
(approximately 1,180 grams of "%.I), or 4 metal waste boxes (approximately 1,180 grams of
?Pu), would exceed the Hazard Category 2 threshold for "'Pu, even if a criticality is precluded
Since the Building 991 Complex can potentially store thousands of waste containers, the
complex can be considered a Hazard Category 2 nuclear facility. This categorization would be
true even if the waste containers had inventories closer to LLW rather than the upper bound
WG Pu content of TRU waste.
Due to the potential "% content of the Building991 Complex waste containers, the
Building 991 Complex is considered a Hazard Category 2 nuclear facility based on exceeding
the Hazard Category 2 radiological threshold for the isotope even though DOE-STD-1027-92
indicates that the inventory found in the TypeB shipping containers does not have to be
considered in the complex inventory.
4.4.3 Hazard Evaluation
The hazard identification process in NSTR-011-98 identified 44 hazards or energy
sources for the Building 991 Complex. Of the 44 hazards, 22 hazards or energy sources were
characterized as Standard Industrial Hazards, which did not need to be carried forward for
further hazard evaluation or analysis. The remaining 22 hazards or energy sources were M er
evaluated using a hazard evaluation process prior to performing an accident analysis for the
Building 991 Complex. The hazards of most interest were Hazard 4 4 Categow I and I1 SNM,
and Hazard 4B, Waste Containers. The remaining hazards and energy sources either act on these
hazards (e.g., Hazard 7 4 Vehicles. Material Handling Eauipment) or are subsets of these
hazards (e.g., Hazard 5D, PvroDhoric Materials). In support of the hazard evaluation process,
logic diagrams were developed displaying the manner in which each of the remaining hazards
and energy sources acted on Hazard 4A and Hazard 4B. It was not considered necessary to
determine how other hazards and energy sources acted on the chemicals since chemicals were
considered to be Standard Industrial Hazards.
Initiating event trees were developed to link 20 of the 22 hazards/energy sources with
releases of the two radioactive material hazards (Le., Category I and I1 SNM and waste
containers). These event trees examined basic phenomenological mechanisms leading to failures
of the SNM or waste containers. Paths through the event trees were preliminary accident
Revision 1
4-13 Building 99 1 Complex FSAR
Scptcrnber 1993 I
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