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Morohashi, Yuko; Suzuki, Satoshi
Proceedings of 2014 International Congress on the Advances in Nuclear Power Plants (ICAPP 2014) (CD-ROM), p.624 - 630, 2014/04
Monju has failed fuel detection systems which consist of the delayed neutron (DN) monitoring system, the cover gas (CG) monitoring system, and the failed fuel detection & location (FFDL) system based on the tagging gas analysis. The DN method and the CG method are used to watch the integrity of fuel assemblies continuously. When a fuel failure of pin-hole level is detected by the CG monitoring, the FFDL system starts operation to identify the location of the failed fuel assembly in the reactor core. In case of a larger fuel failure, the DN monitoring system works and the reactor shuts down automatically. The FFDL system collects the tagging gas which migrates into the reactor cover gas from a failed pin. The tagging gas is made of stable isotopes of Kr and Xe. 270 types of isotopic composition are available using 15 types for Kr and 9 types for Xe. Thus, the isotopic composition of the tagging gas can be made specific to each assembly. The assembly containing a failed fuel pin in the reactor core can be identified by analyzing the isotopic composition. The FFDL system is comprised of two tagging gas concentration devices. The device collects and concentrates the tagging gas by adjusting temperature of activated carbon from 110 K to 420 K. The concentration rate is designed to be higher than 200. In the past examination performed, it was confirmed that the concentration rate meets the requirement with a noble gas concentration of 1 ppm. However, the actual noble gas concentration emitted from a failed fuel is assumed to be much lower. In the present study, the performance of FFDL system was demonstrated by measuring low concentration gas of the actual fuel failure level. The sample gas of concentrations ranging 0.1 ppb to 10 ppb was used. As a result, the concentration rate was confirmed to be more than tens of thousands, which sufficiently satisfies the design demand. Moreover, it was confirmed that the concentration dependence of noble gas was small.
Fukaya, Yuji; Goto, Minoru; Ohashi, Hirofumi; Tachibana, Yukio; Kunitomi, Kazuhiko
Proceedings of 2014 International Congress on the Advances in Nuclear Power Plants (ICAPP 2014) (CD-ROM), p.2066 - 2072, 2014/04
Sustainability and economy of energy supply with HTGR fueled by uranium from seawater have been investigated. To sustain the nuclear energy safely by electricity generation with HTGR, the uranium resources must be inexhaustible. Uranium exists in seawater as a solute of huge amount, which is 4.5 billion tons and corresponds to a duration period of approximately 70 thousand years. The uranium dissolved in seawater is in an equilibrium state with the uranium on surface of sea floor, which is approximately a thousand times of the amount dissolved in seawater. This suggests that almost all of the uranium, which is 4.5 trillion tU and corresponds to the duration time of 70 million years, can be recoverable. The uranium from seawater is almost inexhaustible natural resource. The economy of electricity generation using uranium from seawater is assessed for HTGR. As a result, HTGR can realize lower cost than that of LWR using conventional uranium.
Ikeda, Kazumi*; Homma, Yuto*; Moriwaki, Hiroyuki*; Oki, Shigeo
Proceedings of 2014 International Congress on the Advances in Nuclear Power Plants (ICAPP 2014) (CD-ROM), p.1175 - 1183, 2014/04
Nishino, Hiroyuki; Kurisaka, Kenichi; Yamano, Hidemasa; Okano, Yasushi; Sakai, Takaaki
Proceedings of 2014 International Congress on the Advances in Nuclear Power Plants (ICAPP 2014) (CD-ROM), p.978 - 987, 2014/04
Chikazawa, Yoshitaka; Kato, Atsushi; Yamamoto, Tomohiko; Kubo, Shigenobu; Iwasaki, Mikinori*; Hara, Hiroyuki*; Shimakawa, Yoshio*; Sakaba, Hiroshi*
Proceedings of 2014 International Congress on the Advances in Nuclear Power Plants (ICAPP 2014) (CD-ROM), p.523 - 530, 2014/04
JSFR adopts double boundary for all sodium components. However, design measures are investigated for the secondary sodium fire inside the reactor building, which might be assumed as design extension conditions (DECs). Candidates of sodium fire measures in the secondary sodium systems such as sodium drain, nitrogen injection, pressure release valve, catch pan and leak sodium drain system have been compared from the view point of safety. Wide range of sodium fires in the steam generator room have been analyzed evaluating performances of the candidate sodium fire measures.
Kato, Atsushi; Kubo, Shigenobu; Chikazawa, Yoshitaka; Hayafune, Hiroki; Yokoi, Shinobu*; Nakata, Shuhei*; Tani, Akihiro*; Shimakawa, Yoshio*
Proceedings of 2014 International Congress on the Advances in Nuclear Power Plants (ICAPP 2014) (CD-ROM), p.616 - 623, 2014/04
This paper focuses on loss of heat removal system (LOHRS) type event as Design Extension Condition (DEC) and describes candidates design measures to improve the decay heat removal system of JSFR against LOHRS type DEC. The design requirements are determined based on the Safety Design Criteria for Generation-IV Sodium-cooled fast reactor system. Effectiveness and reliability of the candidate design measures are discussed with preliminary evaluations.
Otaka, Masahiko; Kato, Atsushi; Chikazawa, Yoshitaka; Uzawa, Masayuki*; Ide, Akihiro*; Kaneko, Fumiaki*; Hara, Hiroyuki*
Proceedings of 2014 International Congress on the Advances in Nuclear Power Plants (ICAPP 2014) (CD-ROM), p.607 - 615, 2014/04
Responding to the TEPCO's Fukushima Dai-ichi Nuclear Power Station accident, the design study was carried out to enhance cooling function of fuel handling system for Japan sodium-cooled fast reactor (JSFR). Design measures to maintain an FHS cooling function even in case of Design Extension Conditions are studied; such as alternative cooling systems which are independent and diversified from design basis cooling systems. Based on effectiveness evaluations, it was confirmed that these measures have adequate availability against the postulated design extension conditions.
Nabeshima, Kunihiko; Aizawa, Kosuke; Chikazawa, Yoshitaka; Sato, Daisuke*; Ikari, Risako*
Proceedings of 2014 International Congress on the Advances in Nuclear Power Plants (ICAPP 2014) (CD-ROM), p.600 - 606, 2014/04
One of the advantages in features of Japan Sodium-cooled Fast Reactor (JSFR) is that it's free from high-capacity power load or quick activation of emergency power supply because Decay Heat Removal System (DHRS) adopted natural circulation. However, the Emergency Power Supply System of JSFR is reconsidered to improve the reliability for station blackout (SBO) caused by extreme external events after the nuclear accident at Fukushima. A non-class 1E GTG are added for practically elimination of Loss of Heat Removal System (LOHRS), and alternative power supply system composed of small air-cooled DG and lead-acid batteries is newly introduced to maintain class 1E equipment against the long-term station blackout (SBO).
Monti, S.*; Latge, C.*; Long, B.*; Azpitarte, O. E.*; Chellapandi, P.*; Stieglitz, R.*; Eckert, S.*; Ohira, Hiroaki; Lee, J.*; Roelofs, F.*; et al.
Proceedings of 2014 International Congress on the Advances in Nuclear Power Plants (ICAPP 2014) (CD-ROM), p.474 - 481, 2014/04