Accident Analysis cont'd - DOE-STD-1120-1-20050035

DOE-STD-1120-2005/Vol. 1

Administrative controls and SSCs that are "essential" provide significant worker protection

consistent with DOE-STD-3009 discussions of "safety-significant," as well as provisions

described in DOE-STD-1186-2004. These controls should be based on the results of the HA,

and linked to accident events of concern (e.g., Risk Class I or II events as discussed in Appendix

E). A brief description of these controls should be provided, along with the rationale supporting

their selection (see Section 2.4 of this standard).

The primary means for ensuring reliability of SSCs and administrative controls should be

described. This may include a description of specific surveillance requirements or programs, as

well as explicit personnel actions. DOE-STD-1186-2004, Specific Administrative Controls,

provides additional guidance regarding dependability of SACs. This guidance is supplemented

by Section 2.4 of this Standard.

A listing of SMPs and any references to site-wide programs may be presented in summary or

table form. Characteristics of these programs that are specific to environmental restoration

should be the focus of the DSA (e.g., heavy reliance on contamination control element of

Radiation Protection Program). SMPs that must be considered based on applicability are

provided in items 5 and 6 of 10 CFR 830.204 (b). At a minimum, 10 CFR 830, Subpart B, Table

2, requires that environmental restoration activities address emergency preparedness, conduct of

operations, training and qualification, and maintenance management.

Safety SSCs should be described in sufficient detail to support an understanding of the safety

functions being credited. The use of functional criteria may be used, rather than providing

detailed design requirements for specific SSCs. This will facilitate the removal of individual

components and replacement with temporary systems where necessary to facilitate

environmental restoration.

It is expected that there will be less reliance on facility design and administrative features as the

project progresses and as hazardous substances are removed. For example, the operational limits

imposed on a SSC to prevent a release of hazardous substance are no longer valid if the material

has been removed. Care should be taken to ensure that safety controls are not retired

prematurely or that administrative controls are selected in lieu of available, functioning

engineered safety features.

Trigger points, or the conditions that allow step-out of a control should be supported by the

hazard analysis and described in the DSA. The following criteria should be used when

determining if it is appropriate to retire a control from the safety basis:

Hazardous condition being controlled is no longer present.

Hazardous substance's physical form has changed to a less dispersible form.

Hazardous substance quantities are no longer present or have been reduced to the point where

the consequences of releases are no longer a concern.

A DOE pre-approved process for "stepping out of controls" allows the contractor to retire a

control without formally revising the DSA and re-submitting for DOE approval. This process

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