Proposed Review Framework for Design of Pressure Retaining Components in Small Modular Reactor (SMR)

Abstract of the technical paper presented at:
ASME PVP 2018
July 15–20, 2018

Prepared by:
S. Eom, K. Chaudhry, S. Nabel, C. Cole, R. Awad
Canadian Nuclear Safety Commission
X. Duan
SNC-Lavalin Nuclear

Abstract:

A surge of nuclear industry interest in the development of small factory-built nuclear reactors with inherent safety features has been under way for the last few years. The Canadian Nuclear Safety Commission (CNSC), Canada’s nuclear regulation authority, has recently reviewed a number of small modular reactors (SMRs) through a pre-licensing vendor’s design review, per CNSC guidance document GD-385. Some of these SMRs are proposed to operate under high neutron fluxes and at elevated temperatures in order to achieve high thermal efficiencies. Others use highly corrosive cooling mediums. Such operating conditions could accelerate unforeseen degradation mechanisms. Therefore, it is crucial to understand the material behaviour under these conditions in order to develop appropriate design rules for metallic and non-metallic components. The qualification of new materials proposed for SMRs represents a major challenge; in particular for those materials not listed as acceptable materials for nuclear applications in ASME Section II or ASME Section III Division 5 for high temperature reactors. Thus, a systematic approach and a well-designed research and development program is needed to address the knowledge gap in material behaviour in the early design stage for SMRs, so that potential/plausible degradation mechanisms can be accounted for and the structural integrity of mechanical components can be maintained over their design life.

The purpose of this paper is to propose a review framework to systematically identify and resolve technical issues in the early design stage. The review framework will include design aspects to cover classification, loading conditions, materials, in-service inspections prescribed in available design codes, standards, and CNSC documents. This framework could be used as guidance in the design of pressure retaining systems, structures, and components (SSCs) in SMRs. Moreover, this review framework can be used for upcoming SMRs in Canada during the vendor’s design review and licensing review of SMRs.

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