CSA N290.13:25

Preface This is the third edition of CSA N290.13, Environmental qualification of equipment for nuclear power plants . It supersedes the previous editions published in 2018 and 2005 under the title Environmental qualification of equipment for CANDU nuclear power plants. The following are the major changes to this edition: a) updated the Standard definitions to align with CNSC REGDOC-3.6, and the CSA common definitions, to better align with current industry and CSA terminology; b) added an informative Annex C to provide guidance on the calculation of thermal qualified life independently by analysis; c) added guidance as to the acceptable use of analysis in the qualification process, and provided additional flexibility for legacy equipment in operating plants; and d) added recommended margins on radiation dose rate where transient radiation dose rate performance effects exist. This Standard has been written as a general Standard for the establishment and maintenance of an environmental qualification (EQ) program for safety-related equipment in nuclear power plants (NPPs) that are within its scope. It provides generic requirements and methods for such qualification. Safety-related equipment is qualified to ensure the performance of its required safety functions under harsh environmental conditions that result from a design basis accident (DBA). Adherence to this Standard can result in improved public health and safety. The integrated performance of the process systems, instrumentation, and electrical systems limits the consequences of accidents. An NPP safety analysis considers, in part, facilities and their safety system designs in terms of postulated service conditions. Inherent in each analysis are two presumptions that are evaluated. First, designs are such that equipment can actually perform designated safety functions in postulated harsh environments. Second, safety-related components are not degraded by in-service aging to the point where they cannot perform their designated safety functions when required. Production testing, normal service testing, and surveillance might not be able to determine the equipment’s vulnerability to failure resulting from inadequate design, in-service time, or environmental conditions, because of the special environmental stresses associated with some postulated service conditions. Under these circumstances, common-cause failure of redundant safety-related equipment might occur at a time when its safety function is required. It is the fundamental role of EQ to provide reasonable assurance that both design and manufacture permit the equipment to perform its required safety function(s) during normal and accident service conditions. The CSA N-Series Standards provide an interlinked set of requirements for the management of nuclear facilities and activities. CSA N286 provides overall direction to management to develop and implement sound management practices and controls, while the other CSA Group nuclear Standards provide technical requirements and guidance that support the management system. This Standard works in harmony with CSA N286 and does not duplicate the requirements of CSA N286; however, it might provide more specific direction for those requirements. This Standard reflects the operating experience of the Canadian nuclear power industry. Users of this Standard are reminded that the design, manufacture, construction, commissioning, operation, and decommissioning of nuclear facilities in Canada are subject to the provisions of the Nuclear Safety and Control Act and its supporting Regulations. This Standard was prepared by the Subcommittee on Environmental Qualification of Equipment for Nuclear Power Plants, under the jurisdiction of the Technical Committee on Reactor Control Systems, Safety Systems, and Instrumentation for Nuclear Power Plants and the Strategic Steering Committee on Nuclear Standards, and has been formally approved by the Technical Committee. Scope 1.1 Inclusions This Standard specifies the requirements for an EQ program for nuclear power plants (NPPs) (see Figure 1). The EQ program comprises a set of planned and coordinated activities establishing auditable assurance that equipment will a) perform safety functions in a harsh environment following the DBA(s) for which it is credited; and b) meet or exceed its functional and performance requirements, taking into consideration the effects of normal service. Note: While this standard focuses on EQ programs for NPPs, it provides guidance that might be useful for other nuclear facilities, including research reactors and non-reactor facilities where EQ considerations apply. 1.2 Exclusions Equipment demonstrated to be in a mild environment after a DBA are not subject to the requirements of this Standard. Design extension condition (DEC) survivability assessments are outside the scope of an EQ program. However, this Standard provides optional guidance (see Annex B) on how to demonstrate, with reasonable confidence, that equipment and instrumentation credited to operate during DEC will be capable of performing their intended safety function(s) under the expected environmental conditions. Notes: 1) Post-DBA harsh environment conditions addressed by an EQ program are a subset of service conditions required to be addressed as part of overall equipment qualification. Service conditions can also include seismic vibration, severe weather, external floods, electromagnetic interference and radio frequency interference, and fire. Equipment qualification to demonstrate performance in these conditions is outside of this Standard’s scope. For further guidance on equipment qualification, see IEC/IEEE 60780-323. 2) For general requirements on BDBAs, see CSA N290.16. 1.3 Facility lifecycle considerations This Standard presents the requirements for establishing and preserving EQ to confirm the adequacy of the equipment to meet its design intent. This considers a) the effects of aging on equipment’s ability to perform its safety function(s) during and following a DBA; b) the need to minimize common-cause unsafe failures under accident conditions; c) the preservation of EQ during the maintenance or modification of equipment and systems; and d) the procurement of equipment and components. Note: Although life extension projects can change the design life of the plant, maintaining an EQ program as detailed in this Standard, including the change control process, will provide adequate guidance for continued operation. For example, temporary changes in safety functions during different operational states might exist during life-extension projects. 1.4 Conflicts In cases of conflict between this Standard and other Standards that it references, this Standard takes precedence. 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.