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Udagawa, Yutaka; Sugiyama, Tomoyuki; Amaya, Masaki
Proceedings of 2014 Water Reactor Fuel Performance Meeting/ Top Fuel / LWR Fuel Performance Meeting (WRFPM 2014) (USB Flash Drive), 8 Pages, 2014/10
Narukawa, Takafumi; Amaya, Masaki
Proceedings of 2014 Water Reactor Fuel Performance Meeting/ Top Fuel / LWR Fuel Performance Meeting (WRFPM 2014) (USB Flash Drive), 7 Pages, 2014/09
Sato, Isamu; Miwa, Shuhei; Tanaka, Kosuke; Nakajima, Kunihisa; Hirosawa, Takashi; Iwasaki, Maho; Onishi, Takashi; Osaka, Masahiko; Takai, Toshihide; Amaya, Masaki; et al.
Proceedings of 2014 Water Reactor Fuel Performance Meeting/ Top Fuel / LWR Fuel Performance Meeting (WRFPM 2014) (USB Flash Drive), 6 Pages, 2014/09
A new research program on severe accidents is lunched for the evaluation of FP release and transport behavior in BWR system. The purpose of the program is to improve the FP release and transport model using experimental database about FP chemistry focusing on Cs and I chemistry. In this program, effects of B including in control rod materials, B
C for the Cs and I chemistry are paid attention. The experimental database used for the improvement will consist of results to obtain with newly-prepared test device under atmosphere with broad-ranging oxygen and/or steam partial pressure simulated those in BWR. The state of preparation for these experimental studies and analyses is introduced. In addition, the preliminary test was moved into action to show B chemical effect on Cs and I transport under one of the processes, which is deposited Cs compounds and B vapor and aerosol interaction. In this experiment, a "B stripping effect" to deposited CsI was observed.
C control rod in severe accident of LWRShirasu, Noriko; Kurata, Masaki; Ogawa, Toru*
Proceedings of 2014 Water Reactor Fuel Performance Meeting/ Top Fuel / LWR Fuel Performance Meeting (WRFPM 2014) (USB Flash Drive), 6 Pages, 2014/09
In the accident of Fukushima-Daiichi Nuclear Power Plant, degraded fuels containing Zircaloy probably reacted with BC control blades containing stainless steel cladding or blade sheath. Since light elements like B and C are able to react easily with various elements and form various chemical species, several concerns are pointed out, such as variation in volatility and heat generation by oxidation of B and C. The chemical states of degraded fuel were evaluated on the assumption of thermodynamic equilibrium under various conditions of oxygen potential and temperature. The chemical behavior of B affects significantly the variation in oxygen potential with progressing severe accident, and many kinds of volatile compounds are formed by oxidation. The behavior of B causes the changes of volatility of FPs, such as Sr, Cs and Mo.
Kurata, Masaki; Shibata, Hiroki; Sakamoto, Kan*; To, Takehiko*
Proceedings of 2014 Water Reactor Fuel Performance Meeting/ Top Fuel / LWR Fuel Performance Meeting (WRFPM 2014) (USB Flash Drive), 8 Pages, 2014/09
Control blade degradation is predicted to occur at the early stage of severe accident of boiling water reactor. Simulation tests and modeling are being performed by collaboration among JAEA, Hitachi-GE Nuclear Energy (Hitachi-GE), Nippon Nuclear Fuel Development (NFD), and Nippon Steel & Sumitomo Metal Corporation (NSSMC). Preliminary simulation tests under inert atmosphere indicated that complicated chemical reactions progressed and that finally the mixture of degraded control blade and the channel box separated into two parts. The first part rich in Zr had low melting temperature and flowed down from the high temperature region like candling. The second part rich in steel, B, and C mechanically collapsed down at temperatures higher than approximately 1673K. The interaction between the control blade and the channel box was highly exothermic. Preliminary model for control blade degradation is being developed using VOFFLUENT, which successfully simulates the early stage ofthe control blade degradation.
Sakamoto, Kan*; Shibata, Hiroki; Une, Katsumi*; Ouchi, Atsushi*; Aomi, Masaki*; Kurata, Masaki
Proceedings of 2014 Water Reactor Fuel Performance Meeting/ Top Fuel / LWR Fuel Performance Meeting (WRFPM 2014) (USB Flash Drive), 7 Pages, 2014/09
The depth profiles of hydrogen were measured at outer surface of fuel claddings corroded in high temperature steams at 1073-1473 K to examine the barrierness of surface oxide layer against the hydrogen absorption/desorption. The results indicated that the oxide layer would be no longer the barrier against the hydrogen under some conditions although it remained as the barrier against the oxidation.