Overview - std1134990009

DOE-STD-1134-99

I. OVERVIEW

As in all safety disciplines, this Standard can only be constructively put to use by experienced

criticality safety professionals utilizing their professional judgment and expertise. The purpose

of this document is to provide a set of guidelines, not checklists, for use by DOE criticality safety

personnel when reviewing criticality safety evaluations produced by the contractor. This review

guide is intended to provide a consistent framework for assuring that acceptable evaluations are

produced by DOE contractors. This Standard is focused first, on assessing criticality safety; and

second, on literal DOE Order/Rule compliance. It does not deal with issues of routine document

quality assurance that any technical writer should impose upon the product. The Standard

contains complementary material to DOE-STD-3007-93 and associated change notice dated

September 1998. While the Standard is keyed to sections in DOE-STD-3007-93, it is not

necessary that the contractor use this format for documenting criticality safety evaluations. This

formalism is used for convenience and to provide a common frame of reference only. The

reviewer should concern himself only with the technical content of the criticality safety

evaluation, not the format in which it is documented.

From a safety perspective, a graded approach is recommended when reviewing criticality safety

evaluations (CSEs). The most important decision to make prior to reviewing an evaluation of a

fissile material operation is whether or not criticality is credible for the system or process being

analyzed. If, in the judgment of the reviewer, criticality may be credible, but unlikely, then the

reviewer should make sure the arguments presented in the evaluation are supported by identified,

experienced engineering and operational individuals' judgement. However, the conclusion that

criticality is incredible or unlikely in aging facilities is made much more difficult by such things

as lack of accurate facility drawings, incomplete knowledge of holdup, residue and waste

quantities, and lack of experienced operators utilizing administrative controls. Extreme care

should be exercised in concluding that criticality is incredible. Such a conclusion should be made

only after careful consideration of the adequacy of the existing facility characterization and the

impact of historical operations on potential abnormal event scenarios. The reviewer should

assure that the derivation of the conclusion of incredibility of criticality is fully documented.

However, in the preponderance of fissile operations, criticality is both possible and credible.

This Standard is primarily for use with CSEs covering these kinds of operations. While a

comprehensive and thorough review is necessary, some review criteria are flexible (i.e., graded

approach) and these will be pointed out in the Standard.