Suchergebnisse

International audience ; In their roadmap towards the decommissioning of Fukushima Daiichi reactors, the Japanese authorities plan to start removing fuel debris by the end of 2021. To reach this objective, several RetD projects have been launched and subsidized by the Japanese government. In this framework, a French consortium (COMEX Nucleaire/ONET Technologies, CEA and IRSN) has been selected to implement RetD related to the laser cutting of Fukushima Daiichi fuel debris and related dust collection technology. Some of the key aspects of this project are to fabricate representative corium debris simulants, to test laser cutting technique on these simulants and to measure the aerosols and dusts that are released during the debris thermal cutting. This paper concentrates on the first issue.Two representative corium compositions have been selected in-vessel debris having the average of Fukushima Daiichi Unit 2 (1F2) lower head debris composition best estimates from the OECD Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Station (BSAF); ex-vessel debris composition chosen from DOE calculations on Fukushima Daiichi Unit 1 (1F1) molten core concrete interaction in order to maximize the concrete content and bound the possible composition space.Fission Products expected 10 years after plant shutdown have also been taken into account. As it was not possible within the current project timeframe to perform debris cutting tests with (depleted) uranium oxide, it has been necessary to simulate uranium oxide and hafnium oxide has been considered as the best option.Based on its 20 year experience in corium experimental RetD, PLINIUS platform at CEA Cadarache has been chosen to fabricate these simulants. Two blocks of 8-10 kg have been induction melted. After melting and cooling, samples have been analyzed (microstructure and chemical composition) and laser cutting of these simulant blocks has been successfully carried out.

International audience ; In their roadmap towards the decommissioning of Fukushima Daiichi reactors, the Japanese authorities plan to start removing fuel debris by the end of 2021. To reach this objective, several RetD projects have been launched and subsidized by the Japanese government. In this framework, a French consortium (COMEX Nucleaire/ONET Technologies, CEA and IRSN) has been selected to implement RetD related to the laser cutting of Fukushima Daiichi fuel debris and related dust collection technology. Some of the key aspects of this project are to fabricate representative corium debris simulants, to test laser cutting technique on these simulants and to measure the aerosols and dusts that are released during the debris thermal cutting. This paper concentrates on the first issue.Two representative corium compositions have been selected in-vessel debris having the average of Fukushima Daiichi Unit 2 (1F2) lower head debris composition best estimates from the OECD Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Station (BSAF); ex-vessel debris composition chosen from DOE calculations on Fukushima Daiichi Unit 1 (1F1) molten core concrete interaction in order to maximize the concrete content and bound the possible composition space.Fission Products expected 10 years after plant shutdown have also been taken into account. As it was not possible within the current project timeframe to perform debris cutting tests with (depleted) uranium oxide, it has been necessary to simulate uranium oxide and hafnium oxide has been considered as the best option.Based on its 20 year experience in corium experimental RetD, PLINIUS platform at CEA Cadarache has been chosen to fabricate these simulants. Two blocks of 8-10 kg have been induction melted. After melting and cooling, samples have been analyzed (microstructure and chemical composition) and laser cutting of these simulant blocks has been successfully carried out.