Accident Analysis - DOE-STD-1120-1-20050025

DOE-STD-1120-2005/Vol. 1

assuming failure of Safety SSC during NPH, specific administrative controls may be needed to

augment or supplement the Safety SSC.

3.2.3 Accident Analysis

The vast majority of decommissioning projects are not expected to require detailed analysis and

quantification of accidents, given the magnitude of remaining radionuclide inventory and

associated consequences (i.e., typically well below the Evaluation Guideline). However, for

those HC2 facilities undergoing decommissioning that have potential scenarios with

consequences that could challenge or exceed the EG, an accident analysis should be provided

with explicit calculations for both the source term and consequences sections (i.e., in accordance

with sections 3.4.2.X.2 and 3.4.2.X.3, using DOE-STD-3009 safe harbor format). Unmitigated

source terms and consequences should also be considered for points in time in which anticipated

step-out conditions will apply. These step-out conditions could be decreased hazardous

materials inventories and/or changes in material forms that are likely to be present during the

decommissioning activity. This can then serve as the bases for the change in safety control

designation or elimination of controls.

3.3

Hazard Controls

A summary of the controls that require TSR coverage based on the hazard/accident analysis

results should be presented according to the type of control being established (safety SSC, SAC,

or safety management program). Controls should be linked to specific hazards and accidents

identified in the DSA and considerate of the spectrum of activities anticipated during the entire

decommissioning project. Since fire ranks among the predominate hazards of concern, the

criteria specified in Section 10 of DOE-G 440.1-5 should be applied when determining

appropriate controls for fire hazards. Specific administrative controls should be established

based on considerations given in Section 2.4 of this Standard and DOE-STD-1186.

A listing of safety management programs (SMPs) and any references to site-wide programs and

facility-specific characteristics may be presented in summary or table form, rather than

individual chapters as specified in DOE-STD-3009. 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 facility decommissioning address emergency preparedness.

Similarly, decommissioning activities with only low-level residual fixed radioactivity must at

least address emergency preparedness, conduct of operations, training and qualification, and

maintenance management.

The control hierarchy presented in Appendix A of DOE-STD-3009 should be followed for

decommissioning (as appropriate based on deconstruction activities), which gives priority to

engineered safety features over administrative controls, and preventive over mitigative controls.

Where safety SSCs are needed, information consistent with DOE-STD-3009, Chapter 4 should

be presented. In some cases, decommissioning activities may benefit from the use of temporary

SSCs because existing systems may not be reliable or the nature of decommissioning may

involve some physical alterations of the existing systems. The use of functional criteria may be

appropriate, rather than providing detailed design requirements and system descriptions for

specific SSCs. This will facilitate accomplishment of the safety function using either a

3-8