Dose Comparison Calculations

DOE-STD -3009-94

Appendix A

10-7 per year, realistically calculated.

Unmitigated release is meant to consider material quantity, form, location, dispersability,

and interaction with available energy sources, but not to consider safety features (e.g.,

ventilation systems, fire suppression, etc.) which would prevent or mitigate a release.

Final dose estimations representing the anticipated behavior of the facility under accident

conditions should be based on the mitigated design basis accidents (DBAs), wherein full

or partial functionality of SC SSCs is assumed. In cases where the designated SC SSC are

not capable of performing their required safety function without significant upgrade (i.e.,

backfit) other compensatory measures such as material-at-risk (MAR) limits may be

implemented in the facility and incorporated into the DSA.

Comparison of the unmitigated consequences for a limited subset of potential accidents to

the EG is performed to determine if the need for designation of SC SSCs exists. If the EG

value is approached by the unmitigated consequences of a release scenario, a need for SC

SSC designation is indicated. SC SSCs are only one of many layers of hardware- and

administrative-based controls that are incorporated into a DOE operation for the protection

of the public, worker, and environment consistent with the precepts of the defense- in-depth

philosophy. The SC designation merely helps to focus a higher level of attention and

requirements on this select subset of all controls intended for the protection of the public.

If the need for SC designation is determined, all preventive and mitigative features

associated with the sequence of failures that result in a given release scenario, as well as

any features whose functionality is assumed a s part of the scenario definition itself are

candidates for SC SSC designation. The process of designating one or more safety SSCs

as SC is judgment-based and depends on many factors such as effectiveness, a general

preference of preventive over mitigative and passive over active, relative reliability, and

cost considerations.

A.3

DOSE COMPARISON CALCULATIONS

General discussion is provided for source term calculation and dose estimation, as well as

prescriptive guidance for the latter. The intent is that calculations be based on reasonably

conservative estimates of the various input parameters.

The dose estimate is that received during a 2- hour (with the exception mentioned earlier)

exposure to plume, as discussed in section A.3.3, considering inhalation, direct shine, and

ground shine. Other slow developing release pathways, such as ingestion of contaminated

food, water supply contamination, or resuspension are not included. However, quick

release accidents involving other pathways, such as a major tank rupture, which could

release large amounts of radioactivity in liquid form to water pathways, should be

considered. In this case, real potential uptake locations should be the evaluation points.

The airborne pathway is of primary interest for nonreactor nuclear facilities. This position

is supported by NUREG-1140, "A Regulatory Analysis on Emergency Preparedness for

Fuel Cycle and Other Radioactive Material Licenses," which states that "for all materials

of greatest interest for fuel cycle and other radio active material licenses, the dose from the

inhalation pathway will dominate the (overall) dose." For some types of facilities such as

waste storage, the surface and groundwater pathways may be more important, but accident

releases usually would be expected to develop more slowly than airborne releases. More

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