Evaluation and Results - s3007cn10067

DOE-STD-3007-93

6.0 EVALUATION AND RESULTS

The most reactive pit condition during normal, planned operations is when it is enclosed in High

Explosives (HE). Since water is a better neutron reflector than HE, regardless of the thickness,

thick water reflection is a bounding condition for normal operations that permits ease of analysis.

The fissile mass in this pit is substantially less than the water reflected critical mass as published in

LA-10860-MS2, Table XYZ.

Internal pit flooding is arguably an incredible upset condition for planned operations at the NTS.

However, even this condition, combined with thick water reflection, is easily demonstrated to be

far subcritical based on comparisons to critical mass data in Figures XX and YY of LA-10860-

MS2.

For the pit shipment in an AL-R8 container, a comparative analysis demonstrates that a transport

index of zero is appropriate for criticality control. By comparing fissile masses and dimensions, it

is obvious that the Imaginary Pit is less reactive than the type ABC pit that has been previously

analyzed, shown to have a transport index of zero for criticality control, and approved for

shipment in the AL-R81,3.

7.0

DESIGN FEATURES (PASSIVE & ACTIVE) AND ADMINISTRATIVELY

CONTROLLED LIMITS AND REQUIREMENTS

Beyond the design features inherent to the AL-R8, there are no design features or administratively

controlled limits that are required to ensure criticality safety during shipment of the device for the

Imaginary Event. For operations at the NTS, assembly procedures4 limit the number of fissile

components present at any location such that no credible criticality threat is foreseeable.

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