Example Background

DOE-HDBK-3010-94

7.0 Application Examples; Introductory Material

For this reason, it is typically useful to limit model definition only to the level of complexity

necessary to support the evaluation process, and to perform engineering analysis in source

term estimation only to the level necessary to identify the appropriate release fraction

category. Resolution of highly complex models is problematic, and can cause undue focus

on release quantification at the expense of the overall evaluation process, which is designed

to identify tangible improvements in safety based on many considerations other than source

term estimates. To assist in model development at an appropriate level, this handbook has

made extensive efforts to relate release data to phenomena with some generic applicability to

the typical industrial accidents associated with nonreactor nuclear facilities, thus providing a

straightforward reference for many circumstances. The application examples in the

remainder of this chapter are designed to show both release fraction determination for an

accident model and source term use within the context of the overall evaluation process.

7.2

EXAMPLE BACKGROUND

The examples are based on a mock operation described in Appendix B, which was developed

by the DOE Office of Defense Programs for hazard analysis training. This makes it a

reasonable vehicle for examining ARF and RF selection within the context of an overall

analysis effort. The portions of the mock operation examined are a plutonium processing

facility, an auxiliary lab, and a solid waste handling facility. A basic hazard identification

for the mock operations is provided in Appendix B to assist in focusing discussion.

The examples follow a common format, beginning with a brief top-level summary of hazards

associated with a given operation that identifies the most significant airborne release

potentials. Sufficient detail is provided to understand source term model development, but

this handbook is not an exhaustive treatise on accident phenomena. Bounding material-at-risk

and damage ratios for given accidents are estimated as part of physical model development,

ARFs and RFs are assigned in accordance with the information provided in this handbook,

and an initial respirable source term at the point of release is estimated. Individual examples

conclude with an assessment of results. The discussion in the examples represents the level

of modelling rigor generally adequate for assignment of ARF and RF values.

When reviewing the examples provided, it is important to keep in mind that the focus is on

developing a practical model, not on obtaining an absolute representation of the potential

phenomena. A number of models are possible, and each might be appropriate for a given

need. For example, if it is desired to demonstrate that a facility with small amounts of

material is an insignificant hazard, simply assuming that 100% of the material is released

could suffice. If, however, a more restrictive criteria of what is insignificant is subsequently

adopted, the extreme model previously used may not satisfy the given need. It need not be

attributed any special significance or meaning simply because it has a precedent, and can be

abandoned in favor of a credible bounding ARF based on facility-specific information.

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