MELCOR modeling of Fukushima unit 2 accident

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

Abstract

A MELCOR model of the Fukushima Daiichi unit 2 accident was created in order to get a better understanding of the event and to improve severe accident modeling methods. The measured pressure and water level could be reproduced relatively well with the calculation. This required adjusting the RCIC system flow rates and containment leak area so that a good match to the measurements is achieved. Modeling of gradual flooding of the torus room with water that originated from the tsunami was necessary for a satisfactory reproduction of the measured containment pressure. The reactor lower head did not fail in this calculation, and all the fuel remained in the RPV. 13 % of the fuel was relocated from the core area, and all the fuel rods lost their integrity, releasing at least some volatile radionuclides. According to the calculation, about 90 % of noble gas inventory and about 0.08 % of cesium inventory was released to the environment. The release started 78 h after the earthquake, and a second release peak came at 90 h. Uncertainties in the calculation are very large because there is scarce public data available about the Fukushima power plant and because it is not yet possible to inspect the status of the reactor and the containment. Uncertainty in the calculated cesium release is larger than factor of ten.
Original languageEnglish
Title of host publication22nd International Conference Nuclear Energy for New Europe Proceedings
EditorsLeon Cizelj, Matjaž Leskovar, Mitja Uršič
Place of PublicationLjubljana
Publication statusPublished - 2013
MoE publication typeA4 Article in a conference publication
Event22nd International Conference Nuclear Energy for New Europe, NENE 2013 - Bled, Slovenia
Duration: 9 Sep 201312 Sep 2013

Conference

Conference22nd International Conference Nuclear Energy for New Europe, NENE 2013
Abbreviated titleNENE 2013
CountrySlovenia
CityBled
Period9/09/1312/09/13

Fingerprint

accident
containment
cesium
modeling
noble gas
tsunami
radionuclide
power plant
water level
flooding
earthquake
calculation
water
reactor

Keywords

  • nuclear safety
  • severe accidents
  • Fukushima
  • MELCOR

Cite this

Sevon, T. (2013). MELCOR modeling of Fukushima unit 2 accident. In L. Cizelj, M. Leskovar, & M. Uršič (Eds.), 22nd International Conference Nuclear Energy for New Europe Proceedings [404] Ljubljana.
Sevon, Tuomo. / MELCOR modeling of Fukushima unit 2 accident. 22nd International Conference Nuclear Energy for New Europe Proceedings . editor / Leon Cizelj ; Matjaž Leskovar ; Mitja Uršič . Ljubljana, 2013.
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title = "MELCOR modeling of Fukushima unit 2 accident",
abstract = "A MELCOR model of the Fukushima Daiichi unit 2 accident was created in order to get a better understanding of the event and to improve severe accident modeling methods. The measured pressure and water level could be reproduced relatively well with the calculation. This required adjusting the RCIC system flow rates and containment leak area so that a good match to the measurements is achieved. Modeling of gradual flooding of the torus room with water that originated from the tsunami was necessary for a satisfactory reproduction of the measured containment pressure. The reactor lower head did not fail in this calculation, and all the fuel remained in the RPV. 13 {\%} of the fuel was relocated from the core area, and all the fuel rods lost their integrity, releasing at least some volatile radionuclides. According to the calculation, about 90 {\%} of noble gas inventory and about 0.08 {\%} of cesium inventory was released to the environment. The release started 78 h after the earthquake, and a second release peak came at 90 h. Uncertainties in the calculation are very large because there is scarce public data available about the Fukushima power plant and because it is not yet possible to inspect the status of the reactor and the containment. Uncertainty in the calculated cesium release is larger than factor of ten.",
keywords = "nuclear safety, severe accidents, Fukushima, MELCOR",
author = "Tuomo Sevon",
note = "Project: 81480",
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language = "English",
isbn = "978-961-6207-36-2",
editor = "Leon Cizelj and Matjaž Leskovar and {Uršič }, Mitja",
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Sevon, T 2013, MELCOR modeling of Fukushima unit 2 accident. in L Cizelj, M Leskovar & M Uršič (eds), 22nd International Conference Nuclear Energy for New Europe Proceedings ., 404, Ljubljana, 22nd International Conference Nuclear Energy for New Europe, NENE 2013, Bled, Slovenia, 9/09/13.

MELCOR modeling of Fukushima unit 2 accident. / Sevon, Tuomo.

22nd International Conference Nuclear Energy for New Europe Proceedings . ed. / Leon Cizelj; Matjaž Leskovar; Mitja Uršič . Ljubljana, 2013. 404.

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

TY - GEN

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N1 - Project: 81480

PY - 2013

Y1 - 2013

N2 - A MELCOR model of the Fukushima Daiichi unit 2 accident was created in order to get a better understanding of the event and to improve severe accident modeling methods. The measured pressure and water level could be reproduced relatively well with the calculation. This required adjusting the RCIC system flow rates and containment leak area so that a good match to the measurements is achieved. Modeling of gradual flooding of the torus room with water that originated from the tsunami was necessary for a satisfactory reproduction of the measured containment pressure. The reactor lower head did not fail in this calculation, and all the fuel remained in the RPV. 13 % of the fuel was relocated from the core area, and all the fuel rods lost their integrity, releasing at least some volatile radionuclides. According to the calculation, about 90 % of noble gas inventory and about 0.08 % of cesium inventory was released to the environment. The release started 78 h after the earthquake, and a second release peak came at 90 h. Uncertainties in the calculation are very large because there is scarce public data available about the Fukushima power plant and because it is not yet possible to inspect the status of the reactor and the containment. Uncertainty in the calculated cesium release is larger than factor of ten.

AB - A MELCOR model of the Fukushima Daiichi unit 2 accident was created in order to get a better understanding of the event and to improve severe accident modeling methods. The measured pressure and water level could be reproduced relatively well with the calculation. This required adjusting the RCIC system flow rates and containment leak area so that a good match to the measurements is achieved. Modeling of gradual flooding of the torus room with water that originated from the tsunami was necessary for a satisfactory reproduction of the measured containment pressure. The reactor lower head did not fail in this calculation, and all the fuel remained in the RPV. 13 % of the fuel was relocated from the core area, and all the fuel rods lost their integrity, releasing at least some volatile radionuclides. According to the calculation, about 90 % of noble gas inventory and about 0.08 % of cesium inventory was released to the environment. The release started 78 h after the earthquake, and a second release peak came at 90 h. Uncertainties in the calculation are very large because there is scarce public data available about the Fukushima power plant and because it is not yet possible to inspect the status of the reactor and the containment. Uncertainty in the calculated cesium release is larger than factor of ten.

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M3 - Conference article in proceedings

SN - 978-961-6207-36-2

BT - 22nd International Conference Nuclear Energy for New Europe Proceedings

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Sevon T. MELCOR modeling of Fukushima unit 2 accident. In Cizelj L, Leskovar M, Uršič M, editors, 22nd International Conference Nuclear Energy for New Europe Proceedings . Ljubljana. 2013. 404