Inservice Testing for Small Modular Nuclear Reactor Plants

Abstract

The American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, “OM Code: Section IST,” defines a post-2000 plant as a nuclear power plant that was issued (or will be issued) its construction permit, or combined license for construction and operation, by the applicable regulatory authority on or following January 1, 2000. The NuScale advanced small modular reactor plant is passive, pressurize water reactor, designed such that from one (1) to twelve (12) nuclear power plant modules (NPM) can operate within a single Reactor Building. Each NuScale Power Module (NPM) consist of a reactor core, two steam generator tube bundles, and a pressurizer contained within a single reactor vessel, along with the containment vessel that immediately surrounds the reactor vessel and is rated at 160 MWt. The ASME Operation and Maintenance (OM) Code was written considering single-unit reactor plants, not multi-modular SMRs. The ASME Sub-Committee, New Reactors is developing a new Sub-Section, ISTG to address inservice testing (IST) of valves for all new and advanced reactor types. This paper reviews the unique aspects and programmatic solutions for preservice testing (PST) and IST specific to the NuScale small modular reactor (SMR). The functional design, qualification provisions and IST program is described. The PST and preservice test period will be discussed as some preservice testing may be completed in the factory prior to shipping the reactor module to the site. Additionally, methods eliminate overlap, redundancy and excessive testing between the preservice testing (PST) and IST program plans will be explored. The intent of these solutions is to provide reasonable assurance that the ASME BPV Code, Section III Class 1, Class 2, Class 3, non-safety-related and non-ASME valves that have an important function will operate when needed. The program considers both deterministic and risk insights in its evaluation of PST and IST and meets the requirements of the ASME OM Code as endorsed by 10 CFR 50.55a. Paper published with permission.