> About ISSRD > Introduction


  • Innovative System Safety Research Division(ISSRD) is committed to perform fundamental and application R&D in the fields of thermal hydraulics and safety, severe accident mitigation technology and improvement of PHWR safety. The main tasks include, but are not limited to, the followings:
  • Thermo-fluid dynamic experiment for the reactor core, systems, components, and containment
  • Development of physical modeling for thermo-fluid dynamic phenomena
  • Development, assessment and verification of new safety concepts for advanced reactors
  • Technology development for resolution of safety issues of LWRs
  • Development of thermal-hydraulic safety analysis and severe accident analysis codes
  • Development of advanced energy technologies for non-nuclear application
  • Behavior of in-vessel and ex-vessel corium melt
  • Chemistry and physical behavior of fission product
  • Safety improvement of PHWR relevant safety issues
  • The ISSRD is making sincere efforts to achieve its mission of ‘Creation and Dissemination of Core Technologies (Basic and Application) for Nuclear Thermal-Hydraulics Safety and Severe Accident Mitigation’ by contributing to
  • Development and assessment of safety evaluation and enhancements technologies,
  • Leading the development of future technologies,
  • Contributing to resolving safety issues and concerns worldwide,
  • Playing a role as a think tank for domestic and international nuclear communities.
  • The research efforts includes design, construction and operation of experimental infrastructure, production of quality controlled experimental database, development of physical models for thermal-hydraulic and severe accident phenomena, development of thermal-hydraulic safety analysis and severe accident analysis code. The R&D outcomes help to improve and strengthen nuclear safety and the effectiveness of severe accident management. They are being used by regulators, reactor/fuel developers, nuclear power plant operators, and non-nuclear organizations.
  • The ISSRD’s vision of being a ‘Global Leader in Nuclear Thermal Hydraulics Safety and Severe Accident Mitigation Research’ will be realized by leading the advancements in safety research, active participation in international collaborative programs, and contribution to utilizing nuclear technologies world-wide.


  • The ISSRD consists of about 35 regular staff members and ~7 research assistants, including about 25 PhDs. The staff members are well balanced from the viewpoint of their educational background and technical expertise, which mainly include nuclear engineering and mechanical engineering. The ISSRD has established and applied for the ISO-9001 QA management system for “thermal hydraulics and severe accident analysis technology development”, and received the certificate of ISO-9001:2008 and it has been renewed after strict qualification process bi-annually. Domestic and international advisory committee are advising the whole R&D activity to make ISSRD’s R&D more effective. Considering the large number of staffs in the ISSRD, three functional groups: (a) Thermal-Hydraulic Experiments and Modeling, (b) Thermal-Hydraulics and Severe Accident Code Development, and (c) Severe Accident and PHWR Safety Research are very closely operating.
  • Thermal-Hydraulic Experiments and Modeling Group is involved mainly in thorough understanding of thermo-fluid dynamic phenomena occurring in advanced light water reactors (ALWRs) such as APR1400, APR+ and SMART, and partly in developing Gen-IV reactors such as SCWR, SFR and VHTR, and also in new energy conversion concepts such as supercritical pressure CO2 (sCO2) cycle. This group is also involved in evaluating the predictability of new analysis codes, such as MARS, MARS-KS, SPACE and CUPID, based on its own experimental data, and in developing advanced physical models for both new codes and reactors. For value-added work relevant to these tasks, advanced measurement techniques are continuously being developed in this group.
  • Thermal-Hydraulics and Severe Accident Code Development Group is in charge of developing and verifying/validating safety analysis codes, such as MARS-KS and SPACE as system analysis codes, CUPID as a component analysis code, CINEMA as a severe accident code, ViSA as a plant analyzer, and many numerical simulators, like MARS-SIM, for power reactors and research reactors, such as OPR1000, APR1400, SMART, and HANARO and JRTR. This group also deals with the technology development of coupling between thermal-hydraulic analysis codes with the codes from other technical disciplines of reactor physics, severe accidents and nuclear fuels, such as MASTER, DeCART, COMPASS, looking for more advanced safety analysis.
  • Severe Accident and PHWR Safety Research Group is mainly involved in in- and ex-vessel corium behavior with TROI and VESTA, hydrogen behavior in the containment with SPARC, fission product behavior with ARIEL, and PHWR safety enhancement research such as assessment technology development for life and integrity of aged PHWR pressure tube and SA management technology development.