Summary and Conclusions

DOE-STD-3007-93

Both chemical analysis values must be < 0.1 gram fissile/liter,

before permitting the loading of EBR/TRR material into the

dissolver.

The last rinse must be transferred out, before permitting the loading

of the EBR/TRR dissolution materials into the dissolver.

The performance of the above items (3A, and 3B to 3D if

necessary) by the process operator must be independently verified

by a second individual, such as a supervisor.

8.0

Summary and Conclusions

A nuclear criticality safety evaluation (NCSE), including a double contingency analysis (DCA),

was conducted regarding the dissolution of EBR-II bundle DU006, and 81 TRR bundles, in the

Feanyon annular dissolver in four dissolver batches. An NCSE and DCA (Ref. 1 and 2) were

previously performed for dissolution of TRR rods in the F-canyon dissolver. The difference in

this NCSE, relative to Ref. 1 and 2, is that one EBR-II bundle (DU006) is also to be dissolved,

and that it will be placed by itself into a dissolver port without using an insert.

The EBR-II fuel in bundle DU006 is comparable to the fuel in the TRR bundles (Tables 1 to 4),

so that including the EBR-II bundle in the dissolution is a relatively small perturbation on what

has been dissolved in the past. For example, the average equivalent U-235 enrichment (including

a multiplier of 2.0 for plutonium) of the EBR-II bundle is 0.77 %, whereas the average equivalent

U-235 enrichment of the TRR bundles is 0.79 %. The equivalent U-235 loading of the EBR-

II.bundle, which would be loaded by itself into a port, is 2.21 kg, whereas the average equivalent

U-235 loading of six TRR bundles, which would be loaded into a Mark-42/TRR insert, is 2.29 kg.

Based on safe limits (13.1 kg U-235 at 1.0 % enrichment, and 10.0 kg U-235 at 1.0 %

enrichment) the various allowed configurations in the EBR/TRR dissolution were shown to be

critically safe: the EBR-II bundle DU006 placed in an isolated port (2.21 kg U-235 < 13.1 Kg U-

235 safe limit), six maximum plutonium TRR bundles in an isolated Mark-42/TRR insert (3.26 kg

U-235 < 10 kg U-235 safe limit), and the EBR-II bundle DU006 in close proximity to six

maximum plutonium TRR bundles (5.47 kg U-235 < 13.1 kg U-235 safe limit). Allowing for a

double vidation of administrative controls, the most severe credible configuration would result

from grouping 18 TRR rods together with the EBR-II rods. This could result from double

batching and a missing Mark-42/TRR insert. This configuration was also found to be critically

safe (9.09 kg U-235 < 13.1 kg U-235 safe limit).

The DCA initiating events that result from the presence of the TRR bundles in this EBR/TRR

dissolution were dealt with in Ref. 2. The administrative controls used for the previous TRR

dissolution should therefore be adopted for this EBR/TRR dissolution, with changes to handle the

EBR-II bundle, of course. The only new initiating event (IE #3) is the possibility of significant

fissile material being in the dissolver solution before the EBR/TRR materials are loaded into the

dissolver. A criticality safety limit (0.1 g fissile/liter) and criticality safety controls (CSCs) were

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