Current Activities on the 4S Reactor DeploymentDesign Specific/4S/Presentations...¾Sodium-cooled pool type fast reactor ¾Versions – 10 MWe (30MWt) – 50 MWe (135MWt) ¾Main features
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Double Wall Steam Generator (DWSG)Double-wall helical coil type with 30 MWt capacityInner tube leak detection
– Moisture detection in helium between inner and outer tubesOuter tube leak detection
– Helium detection in the intermediate sodium circuit
Sodium
Outer tube
Inner tube
Wire meshand helium
“Development Study of a Wire Mesh Filled Double Wall Tube for FBR Steam Generators”I.Ohshima et.al. Transactions of the Atomic Energy Society of Japan, Vol.36, No.9 (1994)
Passive Decay Heat RemovalNatural air draft & natural circulation– RVACS : Natural air draft outside the guard vessel– IRACS : Natural circulation of sodium and air draft at air cooler
Critical experiment for 4S core has been successfully performed.
R&D has been performed by CRIEPI in collaboration with JAEA as a part of “Innovative Nuclear Energy System Technology (INEST) Development Projects”under sponsorship of MEXT (JAPAN).
The performance of the EM pump has been demonstrated for the rated power condition of 4S in February, 2010
Toshiba Test Facility
(This study is a part of “Development of high temperature electromagnetic pump with large diameter and a passive flow coast compensation power supply to be adapted into medium and small reactors of GNEP” funded by METI.)
10 MWe – 4S : competitive with diesel power plantat remote area
50 MWe – 4S : slightly higher than large LWRs
Economics
To achieve the target,– Reduce on-site construction work by shop fabrication– Mass production– Reduce O&M cost by low maintenance requirements– Simplified spent fuel handling system by long refueling
intervalTo reduce initial financial cost & risk,
– Small reactor– Flexibility to meet increased demand by modular plant
CRBR: Clinch River Breeder Reactor, FSER: Final Safety Evaluation Report, PRISM: Power Reactor Innovative Small Module,PSER: Preliminary Safety Evaluation Report
No other critical issue in developing 4S PDC based on LWR GDC has been identified except sodium-related matters. GDC for sodium-cooled reactors should be established.
Also, no critical issue has been identified in Regulatory Guides applicability except sodium-cooled reactor matters (not specific to 4S).
The 4S design conformance to the Policy Statement on Regulation of Advanced Nuclear Power Plants has been confirmed.
Concluding Remarks4S design incorporates feature such as long-refueling interval, passive safety, low maintenance requirements, and high security.
4S has advantages of ease of operation and maintenance, and flexibility.
10 MWe-4S is now in progress of the pre-application review by USNRC. Toshiba is participating in the activity to establish the LMR regulatory framework. The DA application of 4S to USNRC in 2012 is planned.