Main Findings, Remaining Uncertainties and Lessons Learned from the OECD/NEA BSAF Project

Marco Pellegrini (Corresponding author), Luis Enrique Herranz, Martin Sonnenkalb, Terttaliisa Lind, Yu Maruyama, R. Gauntt, Nathan Bixler, A. C. Morreale, K. Dolganov, Tuomo Sevon, Didier Jacquemain, J. H. Song, H. Hoshi, Y. Nishi, Shinya Mizokami

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    2 Citations (Scopus)

    Abstract

    The OECD/NEA Benchmark Study at the Accident of Fukushima project (BSAF) has started in 2012 until 2018 as one of the earliest responses to the accident at Fukushima Daiichi with 15 participating organizations out of 10 countries (see list of authors). The project divided into two phases addressed the investigation of the accident at Unit 1, 2 and 3 by Severe Accident (SA) codes until 500 h focusing on thermal-hydraulics, core relocation, Molten Corium Concrete Interaction (MCCI) and Fission Product (FP) release and transport. The objectives of OECD/NEA BSAF were to make up plausible scenarios based primarily on SA forensic analysis, support the decommissioning and inform SA codes modeling. The analysis and comparison among the institutes have brought up vital insights regarding the accident progression identifying periods of core meltdown and relocation, and Reactor Pressure Vessel (RPV) and Primary Containment Vessel (PCV) leakage/failure through the comparison with various plant data (presented in the related papers in the same session). The combination of code and inspections results (muon radiography, PCV inspection) has provided a picture of the current status of the debris distribution and plant status. All units present a large relocation of core materials and all of them present ex-vessel debris with Unit 1 and Unit 3 showing evidences of undergoing timely limited MCCI. Uncertainties have been identified in particular on the time and magnitude of events such as corium relocation inside and from the RPV onto cavity floor, RPV and PCV failure events. Main uncertainties resulting from the project are the large and continuous MCCI progression predicted by basically all the SA codes and the leak pathways from RPV to PCV and PCV to reactor building and environment. The OECD/NEA BSAF project represents a pioneering exercise which has set the basis and provided lessons learned not only for code improvement but also for the development of new related projects to investigate in details further aspects of the Fukushima Daiichi accident.
    Original languageEnglish
    Title of host publicationProceedings of the 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-18
    PublisherAmerican Nuclear Society ANS
    Pages1147-1162
    Number of pages16
    ISBN (Electronic)978-0-89448-767-5
    Publication statusPublished - 2019
    MoE publication typeA4 Article in a conference publication
    Event18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019 - Portland, United States
    Duration: 18 Aug 201923 Aug 2019

    Conference

    Conference18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019
    Abbreviated titleNURETH-18
    CountryUnited States
    CityPortland
    Period18/08/1923/08/19

    Fingerprint

    Accidents
    Containment vessels
    Relocation
    Pressure vessels
    Molten materials
    Concretes
    Debris
    Core meltdown
    Uncertainty
    Inspection
    Codes (standards)
    Fission products
    Radiography
    Hydraulics

    Keywords

    • BSAF
    • Fukushima Daiichi NPS accident
    • OECD/NEA
    • SA code

    Cite this

    Pellegrini, M., Herranz, L. E., Sonnenkalb, M., Lind, T., Maruyama, Y., Gauntt, R., ... Mizokami, S. (2019). Main Findings, Remaining Uncertainties and Lessons Learned from the OECD/NEA BSAF Project. In Proceedings of the 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-18 (pp. 1147-1162). American Nuclear Society ANS.
    Pellegrini, Marco ; Herranz, Luis Enrique ; Sonnenkalb, Martin ; Lind, Terttaliisa ; Maruyama, Yu ; Gauntt, R. ; Bixler, Nathan ; Morreale, A. C. ; Dolganov, K. ; Sevon, Tuomo ; Jacquemain, Didier ; Song, J. H. ; Hoshi, H. ; Nishi, Y. ; Mizokami, Shinya. / Main Findings, Remaining Uncertainties and Lessons Learned from the OECD/NEA BSAF Project. Proceedings of the 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-18. American Nuclear Society ANS, 2019. pp. 1147-1162
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    abstract = "The OECD/NEA Benchmark Study at the Accident of Fukushima project (BSAF) has started in 2012 until 2018 as one of the earliest responses to the accident at Fukushima Daiichi with 15 participating organizations out of 10 countries (see list of authors). The project divided into two phases addressed the investigation of the accident at Unit 1, 2 and 3 by Severe Accident (SA) codes until 500 h focusing on thermal-hydraulics, core relocation, Molten Corium Concrete Interaction (MCCI) and Fission Product (FP) release and transport. The objectives of OECD/NEA BSAF were to make up plausible scenarios based primarily on SA forensic analysis, support the decommissioning and inform SA codes modeling. The analysis and comparison among the institutes have brought up vital insights regarding the accident progression identifying periods of core meltdown and relocation, and Reactor Pressure Vessel (RPV) and Primary Containment Vessel (PCV) leakage/failure through the comparison with various plant data (presented in the related papers in the same session). The combination of code and inspections results (muon radiography, PCV inspection) has provided a picture of the current status of the debris distribution and plant status. All units present a large relocation of core materials and all of them present ex-vessel debris with Unit 1 and Unit 3 showing evidences of undergoing timely limited MCCI. Uncertainties have been identified in particular on the time and magnitude of events such as corium relocation inside and from the RPV onto cavity floor, RPV and PCV failure events. Main uncertainties resulting from the project are the large and continuous MCCI progression predicted by basically all the SA codes and the leak pathways from RPV to PCV and PCV to reactor building and environment. The OECD/NEA BSAF project represents a pioneering exercise which has set the basis and provided lessons learned not only for code improvement but also for the development of new related projects to investigate in details further aspects of the Fukushima Daiichi accident.",
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    author = "Marco Pellegrini and Herranz, {Luis Enrique} and Martin Sonnenkalb and Terttaliisa Lind and Yu Maruyama and R. Gauntt and Nathan Bixler and Morreale, {A. C.} and K. Dolganov and Tuomo Sevon and Didier Jacquemain and Song, {J. H.} and H. Hoshi and Y. Nishi and Shinya Mizokami",
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    Pellegrini, M, Herranz, LE, Sonnenkalb, M, Lind, T, Maruyama, Y, Gauntt, R, Bixler, N, Morreale, AC, Dolganov, K, Sevon, T, Jacquemain, D, Song, JH, Hoshi, H, Nishi, Y & Mizokami, S 2019, Main Findings, Remaining Uncertainties and Lessons Learned from the OECD/NEA BSAF Project. in Proceedings of the 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-18. American Nuclear Society ANS, pp. 1147-1162, 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019, Portland, United States, 18/08/19.

    Main Findings, Remaining Uncertainties and Lessons Learned from the OECD/NEA BSAF Project. / Pellegrini, Marco (Corresponding author); Herranz, Luis Enrique; Sonnenkalb, Martin; Lind, Terttaliisa; Maruyama, Yu; Gauntt, R.; Bixler, Nathan; Morreale, A. C.; Dolganov, K.; Sevon, Tuomo; Jacquemain, Didier; Song, J. H.; Hoshi, H.; Nishi, Y.; Mizokami, Shinya.

    Proceedings of the 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-18. American Nuclear Society ANS, 2019. p. 1147-1162.

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

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    AU - Sonnenkalb, Martin

    AU - Lind, Terttaliisa

    AU - Maruyama, Yu

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    AU - Bixler, Nathan

    AU - Morreale, A. C.

    AU - Dolganov, K.

    AU - Sevon, Tuomo

    AU - Jacquemain, Didier

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    AB - The OECD/NEA Benchmark Study at the Accident of Fukushima project (BSAF) has started in 2012 until 2018 as one of the earliest responses to the accident at Fukushima Daiichi with 15 participating organizations out of 10 countries (see list of authors). The project divided into two phases addressed the investigation of the accident at Unit 1, 2 and 3 by Severe Accident (SA) codes until 500 h focusing on thermal-hydraulics, core relocation, Molten Corium Concrete Interaction (MCCI) and Fission Product (FP) release and transport. The objectives of OECD/NEA BSAF were to make up plausible scenarios based primarily on SA forensic analysis, support the decommissioning and inform SA codes modeling. The analysis and comparison among the institutes have brought up vital insights regarding the accident progression identifying periods of core meltdown and relocation, and Reactor Pressure Vessel (RPV) and Primary Containment Vessel (PCV) leakage/failure through the comparison with various plant data (presented in the related papers in the same session). The combination of code and inspections results (muon radiography, PCV inspection) has provided a picture of the current status of the debris distribution and plant status. All units present a large relocation of core materials and all of them present ex-vessel debris with Unit 1 and Unit 3 showing evidences of undergoing timely limited MCCI. Uncertainties have been identified in particular on the time and magnitude of events such as corium relocation inside and from the RPV onto cavity floor, RPV and PCV failure events. Main uncertainties resulting from the project are the large and continuous MCCI progression predicted by basically all the SA codes and the leak pathways from RPV to PCV and PCV to reactor building and environment. The OECD/NEA BSAF project represents a pioneering exercise which has set the basis and provided lessons learned not only for code improvement but also for the development of new related projects to investigate in details further aspects of the Fukushima Daiichi accident.

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    Pellegrini M, Herranz LE, Sonnenkalb M, Lind T, Maruyama Y, Gauntt R et al. Main Findings, Remaining Uncertainties and Lessons Learned from the OECD/NEA BSAF Project. In Proceedings of the 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH-18. American Nuclear Society ANS. 2019. p. 1147-1162