Discussion of Contigencies

DOE-STD-3007-93

A detailed outline of the various contingencies supporting criticality safety can be found in

the Plant Safety Document (PSD), Section 4.6, "Underwater Fuel Storage".1 In this section

various contingencies are specifically called out along with the results from, and references to,

criticality safety analyses supporting these contingencies.

As discussed previously, the purpose of this evaluation was to determine the reactivity of a

single row of storage buckets placed on the floor of a storage channel in the middle or north basin

of CPP 603. The middle and north basins consist of a series of channels, 12 inches in width

(30.48 cm), through which the monorail system runs. As shown in Figure 21, each channel is

separated by a concrete divider that is 12 inches in width (30.48 cm) and 30 inches high (76.2

cm). Only buckets containing BORAX V Superheater fuel assemblies are considered in this

evaluation.

The BORAX V superheater fuel is a UO2-stainless steel cermet fuel, consisting of highly

enriched uranium (93 weight % U235) dispersed in a stainless steel matrix. A superheater fuel

element is made of five subassemblies of fuel plates with intervening water gaps. Each

subassembly contains four fuel plates. The dimension of each fuel plate is listed as 3.665 inches x

0.030 inches x 25.25 inches (9.309 cm x 0.0762 cm x 64.14 cm), with the fuel meat thickness of

0.014 inches (0.03566 cm) and a stainless steel (304L) cladding thickness of 0.008 inches

(0.02032 cm). Each fuel plate is spaced 0.062 inches (0.1575 cm) apart. The water volume

fraction of a fuel assembly is given as 64.5%. A main underlying assumption of this evaluation is

that the BORAX V Superheater fuel has maintained its structural integrity such that its physical

form does not grossly deviate from that listed in this evaluation. Past basin history indicates that

the stainless steel material which has been stored in the CPP-603 basin environment has good

structural integrity.

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