Draft Details

1.1  General

This Standard specifies the technical requirements for the owner/operator to evaluate cold-worked Zr-2.5 wt% Nb alloy pressure tubes in operating CANDU reactors for continued operation. Clause 13 of CSA N285.0/N285.6 Series requires that when in-service inspection results or material surveillance results do not satisfy the requirements of the original inspection program, a fitness-for-service evaluation must be performed in accordance with CSA N285.4 to demonstrate acceptance. The requirements of this Standard address the specific fitness-for-service evaluation requirements of CSA N285.4, Clause 12.

1.2  Application to pressure tube material type

This Standard applies only to cold-worked Zr-2.5 wt% Nb alloy pressure tubes in operating CANDU reactors and to evaluation of the volumetric inspection results, pressure tube to calandria tube contact, and material surveillance measurements listed herein. The definition of pressure tube material types within the scope of this Standard is provided in CSA N285.6.1.

1.3  Application exclusions

This Standard does not apply to evaluation of pressure tube dimensional changes (other than pressure tube to calandria tube contact), material property surveillance measurements beyond those defined in CSA N285.4, or other reactor types. This Standard does not apply to pressure tube materials other than cold-worked Zr-2.5 wt% Nb.

1.4  Application of standard to lifecycle phases

The requirements of this Standard are applicable to the operational phase of a nuclear power plant, until the fuel is removed from the entire reactor core and up to the time at which systems for cooling of the fuel are drained for the purpose of refurbishment or decommissioning of the reactor core.

This Standard is not applicable to the decommissioning phase of the nuclear power plant life cycle.

1.5  Terminology

In this Standard, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the Standard; “should” is used to express a recommendation or that which is advised but not required; and “may” is used to express an option or that which is permissible within the limits of the Standard.

Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.

Notes to tables and figures are considered part of the table or figure and may be written as requirements.

Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.