Methodology - s3007cn10078

DOE-STD-3007-93

This analysis is designated as Quality Level A (according to the EG&G Idaho Quality

Manual) and is intended to comply with NQA-1. As required by the Nuclear Engineering

Standard Practice, NE-SP-24, any operational limits or procedures that result from or are based

on information contained in this report must be reviewed by Reactor and Radiation Physics

personnel to ensure that the technical information given in this Criticality Safety Evaluation has

been properly incorporated into the limits or procedures.

[Note: Many of the requirements discussed in this evaluation are site specific and company

specific].

All calculations were performed with the one-dimensional Sn (n = 8) discrete-ordinates

transport theory code, ANISN5. Sixteen-energy-group Hansen-Roach6 cross section data were

used as input to the ANISN code. The calculations were performed on an IBM PS/2 Model 60

with a version of the ANISN code that was developed at the INEL, ANISN/PC.

Six thermal reactor benchmarks, PNL-1 through PNL-5 and PNL-7, were evaluated with

the ANISN code and the 16-energy-group Hansen-Roach data set. These experiments are

documented in Reference 7. PNL-1 through PNL-5 are experiments with unreflected spheres of

plutonium nitrate solutions with H/Pu-239 ratios ranging from 131 to 1204. PNL-7 is an

experiment with a water reflected (30-cm-thick) stainless steel sphere of plutonium nitrate with an

H/Pu ratio of 980. These PNL experiments provide adequate validation of the methods and cross

sections used to derive the limits established in this report for the following reasons:

The geometric configurations of the fuel regions are spherical in both the

benchmark experiments and in this analysis.

Both the benchmark experiments and the systems evaluated are hydrogen

moderated. The benchmarks are moderated with nitrate solution. A polyethylene

(60 vol.%) - water (40 vol.%) composition was assumed for this analysis.

4-9