수냉식 소형 모듈 원자로에 대한 통합 및 분리 효과 실험 (Advances in Integral and Separate Effects Experiments for Water Cooled Small Modular Reactors)
본 보고서는 소형 모듈 원자로(SMR) 설계에 있어서의 통합 효과 테스트(IET)와 별도 효과 테스트(SET) 실험 방법 등을 소개합니다.
According to the International Atomic Energy Agency (IAEA), small modular reactors (SMRs) are nuclear reactors with a power capacity per unit up to 300 megawatt electrical (MWe) [1]. By comparison, gigawatt-size reactors can produce electrical outputs up to 1500 MWe. These SMRs are: (a) smaller in size than conventional nuclear power reactors; (b) modular (e.g., mostly factory-assembled power generating units and transported as a unit to plant site); and (c) actual reactors (e.g., they use nuclear fission to generate heat to electricity generation and process heat applications) [1]. There have been over 80 proposals for SMR designs worldwide, thereby reflecting both their potential and a variety of possible nuclear reactor designs [2]. However, to prove the conceptual design needs supportive computer code analysis and experiments. A new reactor design and development process requires component-level and system-level experiments and analysis [3]. Integral effects test (IET) and separate effects test (SET) facilities are used to perform various reactor system transient and accidental experiments for computer code validation and qualification [4–5]. IET experiments involve the testing of the entire reactor system, while SET experiments focus on individual components or subsystems [6]. An IET facility includes all the major components of a reactor system, such as the reactor core region simulated with electrical heaters, the reactor pressure vessel (RPV), pressurizer (PZR), steam generator (SG), accumulators, and containment. However, SET facilities should support counterpart tests, which require detailed studies of the process phenomena. The most common reactor system SET experiments are: (a) containment SET for steam condensation studies; (b) SG SET for studying SG performance with level swelling, tube rupture, and flow instabilities; (c) reactor core (rod bundle) SET for core thermalhydraulics, critical heat flux, and departure from nucleate boiling (DNBR) studies; (d) fuel system irradiation experiments with prototypic reactor conditions; and (d) reactor coolant pump (RCP) SET to validate pump performances. The development of the SET and IET facilities start with phenomena identification and ranking table (PIRT) studies, which identify the phenomena of interest (POI), rank the POIs' importance to the figure of merit, and rank the state of knowledge (SOK) of the POI for the specific reactor design parameters. Then, PIRT studies are needed for a review of the previous reactor system development programs to check the required data availability for assessing the evaluation models (EMs). It is pivotal to ensure data supports the Evaluation Model and Development Assessment Process (EMDAP) by the United States (U.S.) Nuclear Regulatory Commission (NRC) Reg Guide 1.203 [7]. If the data are not available to support EMDAP, then it is required to perform IET and SET experiments to obtain the necessary data to support reactor design. Historically, IET and SET facilities were developed based on scaling to reduce cost and ensure safety. Scaled-down test facility design requires scaling analysis while keeping data scalability from perspectives such as geometry, properties, and phenomena (e.g., event timing, order). The data obtained from the IETs and SETs are considered first category data [8]. Data obtained from the literature or data generated using the standard handbook are considered second category data [8]. The safety of a nuclear reactor is of utmost importance, as its design must take all possible scenarios into account—including normal operation, design-basis accidents (DBAs), and beyond-design-basis accidents (BDBAs). The coupling of thermal, neutronic, and structural systems must be carefully considered when setting design limits to ensure the reactor remains safe and stable under all conditions [9]. The reactor also must be designed with multiple barriers to prevent the release of radioactive materials and general safety criteria must be established to ensure the integrity of these barriers and minimize the risk of harm to people and the environment. However, the IET and SET facilities for thermal-hydraulics (TH) experiments are non-nuclear experiments (i.e., no nuclear/radioactive materials are used). Therefore, it is important to design the IET and SET facilities in a supportive way that matches the conceptual design. Electrical heater rods with a similar geometry size to fuel rods are used in the IET as the heat source. Similarly, a cooling tower or adequate capacity chillers are used as heat sinks to condense steam and return it to the feed water system as part of the closed loop for the reactor cooling water. Over the past 50 years, several standard IET facilities have been developed worldwide to design and license different reactor designs. These include the SemiScale and Loss of Fluid Test (LOFT) at Idaho National Laboratory (INL), the Advanced Plant Experiment (APEX) at Oregon State University (OSU), the Purdue University Multi-Dimensional Integral Test Assembly (PUMA), and the Full Length Emergency Cooling and Heat Transfer (FLECHT) system in the U.S.; the Rig of Safety Assessment (ROSA)/Large Scale Test Facility (LSTF) and Cylindrical Core Test Facility (CCTF) of a pressurized water reactor (PWR) in Japan; the Simulatore per Esperienze di Sicurezza (SPES) in Italy; the Boucle d’Etudes Thermohydrauliques Système (BETHSY) in France; the Parallel Channel Test Loop (PKL) facility in Germany; the Advanced Thermal-hydraulic Test Loop for Accident Simulation (ATLAS) in Korea; and the Advanced Core-cooling Mechanism Experiment (ACME) in China [3–4, 10–12]. These programs and facilities were developed for targeted commercial light water reactors (LWRs), like PWRs and boiling water reactors (BWRs), to examine reactor safety issues related to plant response during a loss-of-coolant accident (LOCA) and operational transient. Few IET facilities have been developed to target SMRs in recent years. The design of IET facilities differs depending on the reactor heat generation in the fuel, power density, coolant, mode of operation, passive safety system, etc.
국내외 전문자료
2023-08-31
국내외 전문자료수냉식 소형 모듈 원자로에 대한 통합 및 분리 효과 실험 (Advances in Integral and Separate Effects Experiments for Water Cooled Small Modular Reactors)
- 국가미국
- 발행기관Idaho National Laboratory (아이다호 국립연구소)
- 원본링크https://www.osti.gov/biblio/1987844
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