The PLiM and LTO considerations for shared facilities or common areas could bring in some specific requirements. Some typical examples are covered in the following:

1.9.1. CONTAINMENT

The IAEA TECDOC on Concrete Containment Buildings [I.4] includes a section on design features of containment for multi-unit CANDUs. The main components of the containment for these NPPs are a common vacuum building (VB) and pressure relief duct (PRD). Up to 8 reactor buildings are connected to the PRD. During normal operation the VB and PRD are isolated from the reactor buildings. An increase in pressure in a reactor building due to an accident will rupture panels so hot gases and steam will flow through the PRD to the vacuum building, and be condensed by a dousing system. There are 2 basic designs of RB at multi­unit CANDUs: 1) domed cylindrical structures with unlined single exterior walls and 2) thick — walled cube shaped structures with steel liner and post tensioned roof beams. The VB and PRD at multi-unit NPPs are reinforced concrete. ARDMs are similar to those discussed in section 3.6.4 for single-unit HWRs.

1.9.2. CONTROL ROOM, CONTROL EQUIPMENT ROOMS, FUELLING MACHINES, etc.

Common areas have been used for control room, cable spreading or control equipment rooms in some multi unit stations. Similarly certain refuelling facilities like fuelling machines, fuel transfer to storage bay could have shared features. This may necessitate taking up related PLiM for life attainment or for long term operation with appropriate management and logistics control such that safety and availability is assured for all units in the process.

REFERENCES TO APPENDIX I

[1.1] INTERNATIONAL ATOMIC ENERGY AGENCY, Assessment and Management of Ageing of Major Nuclear Power Plant Components Important to Safety: CANDU Pressure Tubes, IAEA-TECDOC-1037, IAEA, Vienna (1998).

[1.2] INTERNATIONAL ATOMIC ENERGY AGENCY, Assessment and Management of Ageing of Major Nuclear Power Plant Components Important to Safety: Steam Generators, IAEA-TECDOC-981, IAEA, Vienna (1997).

[1.3] INTERNATIONAL ATOMIC ENERGY AGENCY, Assessment and Management of Ageing of Major Nuclear Power Plant Components Important to Safety: Primary Piping in PWRs, IAEA-TECDOC-1361, IAEA, Vienna (2003)

[1.4] INTERNATIONAL ATOMIC ENERGY AGENCY, Assessment and Management of Ageing of Major Nuclear Power Plant Components Important to Safety: Concrete Containment Buildings, IAEA-TECDOC-1025, IAEA, Vienna (1998).

[1.5] INTERNATIONAL ATOMIC ENERGY AGENCY, Assessment and Management of Ageing of Major Nuclear Power Plant Components Important to Safety: CANDU reactor assemblies, IAEA-TECDOC-1197, IAEA, Vienna (2001).

APPENDIX II