Safety design principle of supercritical water cooled reactors

Conference · Thu Jul 01 04:00:00 EDT 2004

OSTI ID:21160778

Ishiwatari, Y; Oka, Y; Koshizuka, S ^[1]

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1. Nuclear Engineering Research Laboratory, The University of Tokyo, Shirane-Shirakata 2-22, Tokai-mura, Ibaraki, 319-1188 (Japan)

This paper summarizes safety of high temperature supercritical pressure light water cooled and moderated reactor (SCLWR-H) developed by Univ. Tokyo. Although SCLWR-H is a logical evolution of LWR, the cooling system and safety principle are different from it. SCLWR-H is once-through cooling cycle where all the coolant is led to the turbine. The safety design principle of once-through SCLWR-H is to keep core flow rate while keeping water inventory is important in LWR. The safety system of SCLWR-H is similar to that of BWR since both reactors are direct cycle. Cladding temperature is limited at transient instead of heat flux because heat transfer deterioration of single-phase supercritical water is milder than DNB and dryout of subcritical water. A set of safety analyses shows that SCLWR-H safety is maintained. Once-through cooling cycle, relatively small pressure change at supercritical pressure and heat conduction to many water rods characterizes safety behavior of SCLWR-H. Depressurization induces core flow and increases core cooling because high-density water passively flow from the RPV through the ADS. Such effect of depressurization is advantage in SCLWR-H safety. Decrease in water inventory by depressurization is not a problem for SCLWR-H because water inventory is not important safety factor. Another advantage is that ATWS behavior is mild and better than LWR. It is mitigated without scram and depressurization. (authors)

• Research Organization: American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 21160778
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
ATWS
BWR TYPE REACTORS
CLADDING
COOLING
COOLING SYSTEMS
DEPARTURE NUCLEATE BOILING
DEPRESSURIZATION
DESIGN
DRYOUT
HEAT FLUX
SAFETY
SAFETY ANALYSIS
SCRAM
THERMAL CONDUCTION
TURBINES
VISIBLE RADIATION
WATER