Commentary on CSA N285.0-17, General requirements for pressure-retaining systems and components in CANDU nuclear power plants
|Publication Date:||1 January 2018|
The purpose of this Commentary is to provide background information for specific clauses and requirements in CSA N285.0. This background information can help the user to clarify the context of the CSA N285.0 requirements. Also, this Commentary refers to sources of material that were used during the formulation of some of the requirements in CSA N285.0. With the exception of the Annexes, the main clause headings and the main clause numbers used in this Commentary correspond to those in CSA N285.0-17. The numbering for subclauses in the Commentary does not necessarily correspond to those in CSA N285.0-17.
This Commentary focuses on CSA N285.0 and is organized as follows:
a) the original intent of CSA N285.0, including
i) historical background - how the nuclear industry developed in Canada; and
ii) the differences between ASME Boiler and Pressure Vessel Code (BPVC), Section III, Division 1, and CSA N285.0, CANDU-specific requirements;
b) the aim of CSA N285.0, including the provision of
i) rules for the design of the CANDU reactors consistent with regulatory requirements;
ii) requirements not covered by ASME BPVC, Section III, Division 1;
iii) classification requirements;
iv) registration requirements, including those for welding procedures; and
v) requirements for repairs, replacements, and modifications;
c) the rationale for many of the requirements, which are derived from
i) industry practice or experience;
ii) engineering or safety analysis;
iii) research or test programs; and
iv) good engineering judgment; and
d) the development of CSA N285.0 through significant changes in various editions.
This Commentary addresses requirements relating to the design and construction of pressure-retaining systems and components. Standards that relate to periodic inspection of pressure-retaining components are not addressed. Also, the requirements of other interfacing Standards and ASME BPVC, Section III, Division 1 are not addressed in this Commentary. The discussion provided in this Commentary is directed towards the requirements in CSA N285.0-17 and does not address the amendments released since 2017. Generally, the text is presented in the same sequence used in CSA N285.0, tracing the activities during the design, fabrication, and installation of an item.
Although this Commentary can be read by itself, a better understanding of the Commentary will be obtained if a copy of CSA N285.0-17 is available for reference. Many of the requirements in CSA N285.0- 17 are described in this Commentary. However, the Standard must always govern since it provides the formal requirements.
Note: ASME has published a companion guide to the ASME Boiler and Pressure Vessel and Piping Codes, which provides the criteria and a commentary on selected aspects of ASME Boiler and Pressure Vessel and Piping Codes