Hazard Analysis Results cont'd - DOE-STD-1120-1-20050023

DOE-STD-1120-2005/Vol. 1

In general, existing DSAs that were prepared for a previous phase of a facility's life cycle are a

good source of hazard identification and analysis information. Analysts should consider this

information for applicability to decommissioning. Fire hazards analyzed for previous

operational phases can be increased during decommissioning because of intrusive activities and

from equipment, chemicals and techniques introduced during the decommissioning project. This

may increase worker hazards and require more robust fire protection measures than needed

during a facility's operational phase.

Hazards such as natural phenomena will have similar applicability during decommissioning and

should be retained for analysis. Hazard and accident analysis information from previous facility

operations is appropriate for inclusion into decommissioning DSAs if it was previously approved

by DOE as compliant with 10 CFR 830, Subpart B, and is bounding and representative of

activities anticipated during decommissioning (NOTE: Decommissioning may introduce new

hazards and energy sources).

The facility-level hazard analysis supports the safety basis for decommissioning operations and

provides an envelope against which day-to-day work planning and associated task level analysis

are measured. As described in DOE-STD-3009, the level of analysis is driven by the simplicity

of operations and hazard potential. Qualitative analysis will typically suffice for the majority of

decommissioning projects, because operations have been deactivated and hazardous material

inventory has been reduced.

A decommissioning hazard analysis should be considerate of the type of decommissioning

activities, as well as work techniques and sequencing of activities to be employed. The HA

should also be forward looking to capture the expected decommissioning activities and

anticipated facility changes. This includes anticipated changes in control designation as the

project proceeds. Retiring safety SSCs or eliminating SACs should be at the appropriate point

when material inventory or hazardous conditions no longer exist. The HA should be supportive

of these decisions.

There may be cases when hazardous material inventories could be made more dispersible during

decommissioning, thereby requiring new and/or temporary safety SSCs not originally identified

during the initiation of decommissioning. An example of this is the decontamination of a piece

of equipment (e.g., glovebox or furnace) at a facility located close to a site boundary (MEOI

location) with fixed 238Pu contamination. During the decontamination activities, the system may

be breached and mechanical means may be used to remove or reduce the contamination to levels

that allow for disposal of the equipment. Such decontamination activities may result in the

potential increase of dispersible material that could be released to the environment, even

potentially challenging the Evaluation Guideline (EG) of DOE-STD-3009. Therefore,

designating temporary ventilation as safety SSC may be necessary until the hazard is no longer

present.

Facilities entering into a decommissioning phase typically have performed an evaluation of

natural phenomena hazards (NPH) based on a previous 10 CFR 830 compliant DSA. These

evaluations can be utilized in the decommissioning DSA unless significant structural or

equipment modifications are planned that invalidate the conclusions in the previous DSA (e.g.,

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