Decommissioning Scenarios

2 In the following sections the term dismantlement is used to describe the organised, controlled and programmed sequence of events that constitutes the decommissioning process. These events Include, but are not limited to, radiological protection requirements, plant and equipment removal and demolition of structures. For more detailed descriptions of these processes reference should be made to NUREG CR 0130.  

3 Within the terms defined in Section 1.2 of this report, two basic scenarios exist for decommissioning of a PWR. 

Radioactive source and activated materials are removed and the station is decontaminated and dismantled during the immediate period following cessation of power production. Upon completion of dismantlement the property may be released for unrestricted use. 

Radioactive source materials are removed, but activated and contaminated areas are secured to allow radioactivity to decay over a period to significantly lower levels. Only those structures and equipment necessary to ensure protection of the public from residual radioactivity are maintained, all other structures being removed. During this period of safe storage access to the facility remains under the control of a nuclear license. Dismantlement of the storage structures is deferred until radioactivity levels have decayed significantly. Upon completion of dismantlement the property may be released for unrestricted use. 

4 The following orders of timescale apply to the above scenarios. 

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To compare scenarios, and prioritise decommissioning activities as part of the planning process, on the basis of their effectiveness in reducing hazard potential. 

Some scenarios postulated In the literature suggest that Stage 3 of the decommissioning process may be delayed until up to 100 years after shutdown of the plant. 

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