Safety of super LWR, (I) safety system design

Yuki Ishiwatari*, Yoshiaki Oka, Seiichi Koshizuka, Akifumi Yamaji, Jie Liu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


This paper describes design concept of safety system of the high-temperature supercritical pressure light water cooled reactor with downward-flow water rods (Super LWR). Since this reactor is once-through cooling system without water level and coolant circulation, the fundamental safety requirement is keeping core coolant flow rate while that of light water reactors (LWR) is keeping coolant inventory. “Coolant supply from cold-leg” and “coolant outlet at hot-leg” are needed for it. The advantage of the once-through cooling system is that reactor depressurization induces core coolant flow and cools the core. The downward-flow water rod system enhances this effect because the top dome and the water rods supply its water inventory to the core like an “in-vessel accumulator.” The safety system of the Super LWR is designed referring to those of LWR in consideration of its characteristics and safety principle. “Coolant supply” is kept by high-pressure auxiliary feedwater system and low-pressure core injection system. “Coolant outlet” is kept by safety relief valves and automatic depressurization system. The Super LWR is equipped with two independent shutdown systems: reactor scram system and standby liquid control system. The capacities and the actuation conditions determined in this study are to be used in safety analysis.

Original languageEnglish
Pages (from-to)927-934
Number of pages8
JournalJournal of Nuclear Science and Technology
Issue number11
Publication statusPublished - 2005 Nov
Externally publishedYes


  • Downward-flow water rod
  • Once-through cooling cycle
  • Safety principle
  • Safety system design
  • Supercritical-pressure

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering


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