Nakayoshi, Akira; Rempe, J. L.*; Barrachin, M.*; Bottomley, D.; Jacquemain, D.*; Journeau, C.*; Krasnov, V.; Lind, T.*; Lee, R.*; Marksberry, D.*; et al.
Nuclear Engineering and Design, 369, p.110857_1 - 110857_15, 2020/12
Much is still not known about the end-state of core materials in each of the units at Fukushima Daiichi Nuclear Power Station (Daiichi) that were operating on March 11, 2011. The Nuclear Energy Agency of the Organization for Economic Development has launched the Preparatory Study on Analysis of Fuel Debris (PreADES) project as a first step to reduce some of these uncertainties. As part of the PreADES Task 1, relevant information was reviewed to confirm the accuracy of graphical depictions of the debris endstates at the damaged Daiichi units, which provides a basis for suggesting future debris examinations. Two activities have been completed within the PreADES Task 1. First, relevant knowledge from severe accidents at the Three Mile Island Unit 2 and the Chernobyl Nuclear Power Plant Unit 4 was reviewed, along with results from prototypic tests and hot cell examinations, to glean insights that may inform future decommissioning activities at Daiichi. Second, the current debris endstate diagrams for the damaged reactors at Daiichi were reviewed to confirm that they incorporate relevant knowledge from plant observations and from severe accident code analyses of the BSAF (Benchmark Study of the Accident at Daiichi Nuclear Power Station) 1 and 2 projects. This paper highlights Task 1 insights, which have the potential to not only inform future Decontamination and Decommissioning activities at Daiichi, but also provide important perspectives for severe accident analyses and management, particularly regarding the long term management of a damaged nuclear site following a severe accident.
Pshenichnikov, A.; Kurata, Masaki; Bottomley, D.; Sato, Ikken; Nagae, Yuji; Yamazaki, Saishun
Journal of Nuclear Science and Technology, 57(4), p.370 - 379, 2020/04
Pham, V. H.; Nagae, Yuji; Kurata, Masaki; Bottomley, D.; Furumoto, Kenichiro*
Journal of Nuclear Materials, 529, p.151939_1 - 151939_8, 2020/02
Nakayoshi, Akira; Journeau, C.*; Rempe, J.*; Barrachin, M.*; Bottomley, D.; Nauchi, Y.*; Song, J. H.*
Proceedings of 2019 International Workshop on Post-Fukushima Challenges on Severe Accident Mitigation and Research Collaboration (SAMRC 2019) (USB Flash Drive), 6 Pages, 2019/11
Knebel, K.*; Jokiniemi, J.*; Bottomley, D.
Journal of Nuclear Science and Technology, 56(9-10), p.772 - 789, 2019/09
Revaporisation of the fission products deposited in the primary circuit of a reactor was identified as a possible late source of fission product release during a severe accident: eg. loss of coolant accident (LOCA). Subsequent testing has shown that revaporisation is very likely to occur given a breach of the reactor and is an important contributor for the source term release to the containment and biosphere. The first part reviews the revaporisation mechanisms of Cs and other volatile or semi-volatile fission products transported in the primary circuit that were derived from the Phebus FP and associated programmes. The second part examines the separate effects testing to determine the high temperature chemistry ofvolatile and semi-volatile fission products (I, Mo, Ru) and structural materials (Ag, B) as well as atmospheric effects which substantially affect the source term. Finally, it examines Cs data from reactor accident sites that is providing additional knowledge of longer-term fission product chemistry. The results have been summarised in the form of a table and schematic diagram. This accumulated knowledge and experience has important applications to minimising contamination during decommissioning and site remediation techniques, as well as improving SA simulation codes and raising nuclear safety.
Pshenichnikov, A.; Yamazaki, Saishun; Bottomley, D.; Nagae, Yuji; Kurata, Masaki
Journal of Nuclear Science and Technology, 56(5), p.440 - 453, 2019/05
Nakayoshi, Akira; Bottomley, D.; Washiya, Tadahiro
Proceedings of 56th Annual Meeting on Hot Laboratories and Remote Handling (HOTLAB 2019) (Internet), 3 Pages, 2019/00
Miwa, Shuhei; Ducros, G.*; Hanus, E.*; Bottomley, P. D. W.*; Van Winckel, S.*; Osaka, Masahiko
Nuclear Engineering and Design, 326, p.143 - 149, 2018/01
The release and transport behaviors of 13 non-gamma-emitting fission products (FPs) and actinides in steam and hydrogen atmospheres were investigated based on the chemical analysis of their deposits on the components of VERCORS test loops. The new findings were obtained; strontium release was significantly enhanced in hydrogen atmosphere and a part of released strontium was transported towards the lower temperature region, uranium release was enhanced in steam atmosphere but most of released uranium deposited at high temperature region.
Miwa, Shuhei; Ducros, G.*; Hanus, E.*; Bottomley, P. D. W.*; Van Winckel, S.*
Proceedings of 7th European Review Meeting on Severe Accident Research (ERMSAR 2015) (Internet), 11 Pages, 2015/03
The release behaviour of -ray emitters, -ray emitters and stable nuclide from the degraded fuel in the fission product (FP) and actinide release and transport tests, VERCORS tests, were investigated based on the chemical analysis of their deposits on the components of VERCORS test loops. The release of Sr which has a significant public impact shows the possibility to be enhanced in reducing atmosphere. The release of U was significantly enhanced in steam atmosphere, but almost all the released U remained near the fuel. The release behaviour of other non--ray emitters such as Rb, Pd, Tc and Pu shows the good consistency with the expectation based on the previous VERCORS tests results. The experimental database of the FP and actinide release behaviour was upgraded through the chemical analysis in terms of the effects of atmosphere on the release behaviour of -ray emitters, -ray emitters and stable nuclide.
Miwa, Shuhei; Osaka, Masahiko; Ducros, G.*; Hanus, E.*; Bottomley, P. D. W.*; Van Winckel, S.*
no journal, ,
The analysis method of fission product (FP) chemistry for the precise evaluation of the effect of atmosphere on the FP release and transport was investigated by using the results of FP release and transport experiments VERCORS which were carried out at various atmosphere. The results of pseudo chemical kinetics calculation show good consistency with experimental results of FP chemistry in the transport at relative low temperature.