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Vol.7 No.1previous AASP14 (87-88-89-90-91-92-93-94-95-96-97-

Academic Articles
Regular Paper Vol.7 No.1 (2015) p.90 - p.95

The Concept of Passive Cooling Systems for Inherently Safe BWRs

Naoyuki ISHIDA1, Akinori TAMURA2, Toshinori KAWAMURA1, Kazuaki KITOU1, Mamoru KAMOSHIDA1

1 Hitachi, Ltd.,Hitachi Research Laboratory,7-1-1 Omika-cho, Hitachi-shi, Ibaraki-ken, 319-1292, Japan
2 Hitachi Europe, Ltd., European Research Centre, 25 Chapel Street, London


The Fukushima Daiichi Nuclear Power Plant accident and its consequences have led to extensive rethinking about the safety technologies used in boiling water reactors (BWRs). As one of the options of the safety technologies, we have been developing passive cooling systems consisting of a water-cooling system and an infinite-time air-cooling system. These systems achieve core cooling without electricity and are intended to cope with a long-term station blackout (SBO). Both these cooling systems remove relatively high decay heat for the initial 10 days after an accident, and then the infinite-time air-cooling system continues to remove attenuated decay heat after this period.
To obtain heat transfer data for the design of the water-cooling system, we conducted heat transfer tests using a full-scale U-shaped single tube. The data were obtained at a system pressure of 0.2 to 3.0MPa (absolute) and inlet steam velocity of 5 to 56m/s. To enhance heat transfer of the air-cooling system, we successfully implemented some air-cooling enhancing technologies. The performance was evaluated by heat transfer data obtained from the element heat transfer tests. The heat transfer performance increased at least 100% with the enhancement technologies compared with a bare tube. From these test results, we confirmed good feasibility for application of the cooling systems.

BWR, Inherently safe, Passive cooling system, Water-cooling, Air-cooling
Full Paper: PDF EJAM Vol.7No.1 pp.90-95 "The Concept of Passive Cooling Systems for Inherently Safe BWRs"
Article Information
Article history:
Received 31 October 2014
Accepted 27 March 2015