Systems, Structures and Components

DOE-STD-1120-2005/Vol. 1

3.1.2 Systems, Structures and Components

A description of SSCs which are being decommissioned, including a description of buried

structures that will be remediated, should be presented. This information should include the

existing configuration and interdependencies of SSCs, and in particular any degradation or other

changes that may have occurred relative to the original design. A description of new or

temporary SSCs which may be needed to prevent or contain the spread of radioactive or

hazardous materials during decommissioning should also be provided.

Interdependencies among SSCs should be described to the extent they will be affected by the

decommissioning, and to the extent necessary to facilitate an adequate understanding of the

hazard analysis. Equipment being dismantled may be structurally linked to safety SSCs that are

not planned for retirement until a subsequent phase of decommissioning. The means by which

integrity of the remaining structures will be assured should be described.

To the extent possible at the time of DSA preparation, it is important that SSC changes

anticipated during the course of the decommissioning project be described in the DSA to reduce

the potential activities that must be separately evaluated in accordance with the USQ process.

Additionally, the timing of SSC changes within the overall project work scope should be stated

to support proposed rationales for retiring safety controls.

3.1.3 Operational History

Information from the operational history of the facility, which is important in understanding the

hazards and state of SSCs should be compiled. Information on previous modifications to the

design that may have an impact on the safety of decommissioning should be presented.

Operational information about previous facility processes and the location of radioactive

contamination, both as a result of normal operation and resulting from incidents or accidents,

should be also presented.

3.1.4 Decommissioning Activities and Techniques

Since the decommissioning activities themselves, by their nature, can be a source of accident

initiators, it is important that decommissioning equipment and processes be sufficiently

described to the extent necessary to support the hazard analysis and control selection. At the

highest level, this description should include the major phases of decommissioning including the

removal of remaining hazardous material inventory; the removal of fixed contamination from

surfaces and equipment; dismantling of systems and equipment; demolition of major structures;

or other defined end-states for the facility. Where sequencing of these activities is important,

this information should also be presented.

Decommissioning techniques should also be described. The requirements for power, cooling

water, and other external supplies to the equipment used to carry out these techniques should be

documented. Hazardous chemicals, heat or ignition sources, combustible or flammable

materials, or other types of hazards that could be introduced in the facility as a result of the

chosen decommissioning techniques should be described. The expected quantities and location

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