Both chemical analysis values must be < 0.1 gram fissile/liter,
before permitting the loading of EBR/TRR material into the
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.
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