2013 Fiscal Year Final Research Report

Fundamental study of fuel debris treatment by the use of mechanochemical method

Research Project

Project/Area Number	24656564
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Single-year Grants
Research Field	Nuclear engineering
Research Institution	Tohoku University
Principal Investigator	SATO Nobuaki 東北大学, 多元物質科学研究所, 教授 (70154078)
Project Period (FY)	2012-04-01 – 2014-03-31
Keywords	燃料デブリ / ウラン酸化物 / ジルコニウム酸化物 / メカノケミカル処理 / 二硫化炭素 / 選択硫化
Research Abstract	In nuclear reactor accident at Fukushima NPP, the reactor core was damaged by the severe conditions such as very high temperature and sea water injection, forming a huge amount of nuclear fuel waste so called debris fuel. Since UO2 fuel pellets are packed in the zircaloy cladding, the fuel debris consists of the mixture of nuclear fuel and structural materials. In this paper, sulfuization behavior of uranium oxides, zirconium oxide and metal as fuel and structural materials was studied by using carbon disulfide for the sulfurization treatment of fuel debris components. No reaction was observed for Uranium oxides in the presence of CS2 at T<773 K, while metal components, such as zirconium metal shows sulfurization at lower temperature. When the mixture of simulated fuel debris was mechanochemically treated, the interaction of zirconium with UO2 seems to occur forming the UO2-ZrO2 solid solution.