N285.8-05

This is the first edition of CSA N285.8, Technical requirements for in-service evaluation of zirconium alloy pressure tubes in CANDU reactors.

Scope

1.1 This Standard specifies the technical requirements for the licensee to ensure structural integrity of cold-worked Zr-2.5 wt% Nb alloy pressure tubes in operating CANDU reactors. Clause 13 of CAN/CSA-N285.0 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 CSA N285.8 address the specific fitness-for-service evaluation requirements of CSA N285.4, Clause 12.

1.2 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 is provided in CAN/CSA-N285.6 Series.

1.3 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 to other reactor types. This Standard does not apply to pressure tube materials other than cold-worked Zr-2.5 wt% Nb.

1.4 In CSA Standards, 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; may is used to express an option or that which is permissible within the limits of the standard; and can is used to express possibility or capability.

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.