MELCOR modeling of Fukushima unit 2 accident

Research output: Contribution to journalArticleScientificpeer-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
Number of pages9
Journalatw - International Journal for Nuclear Power
Volume59
Issue number12
Publication statusPublished - 2014
MoE publication typeA1 Journal article-refereed
Event22nd International Conference Nuclear Energy for New Europe, NENE 2013 - Bled, Slovenia
Duration: 9 Sep 201312 Sep 2013

Fingerprint

Accidents
Cesium
Tsunamis
Water levels
Inert gases
Radioisotopes
Earthquakes
Power plants
Flow rate
Water
Uncertainty

Cite this

@article{292e78d144754c5f99eb59410f36623b,
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.",
author = "Tuomo Sev{\'o}n",
note = "Project code: 85419",
year = "2014",
language = "English",
volume = "59",
journal = "atw - International Journal for Nuclear Power",
issn = "1431-5254",
number = "12",

}

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

In: atw - International Journal for Nuclear Power, Vol. 59, No. 12, 2014.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - MELCOR modeling of Fukushima unit 2 accident

AU - Sevón, Tuomo

N1 - Project code: 85419

PY - 2014

Y1 - 2014

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.

M3 - Article

VL - 59

JO - atw - International Journal for Nuclear Power

JF - atw - International Journal for Nuclear Power

SN - 1431-5254

IS - 12

ER -