Simulated spatially dependent transient kinetics analysis of the Oak Ridge Y12 plant criticality excursion

Andrew Buchan (Corresponding Author), Christopher Pain, Brendan Tollit, Jefferson L. M. A. Gomes, Matthew D. Eaton, Gerard J. Gorman, Christopher Cooling, Anthony J.H. Goddard, Erick T. Nygaard, Peter L. Angelo, Paul N. Smith

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

In June 1958 an accidental nuclear excursion occurred in the C-1 Wing of building 9212 in a process facility designed to recover enriched Uranium U(93) from various solid wastes. The accident was caused by the inadvertent flow of enriched uranyl nitrate into a 55 gallon drum which established a prompt critical nuclear excursion. Following the initial fission spike the nuclear system oscillated in power. The reaction was eventually terminated by the additional water which was flowing into the drum. The criticality excursion was estimated to have lasted approximately 20 min based upon nearby radiation measurement equipment with an estimated total fission yield of 1.3 × 1018 fissions of which the first fission spike contributed 6 × 1016 fissions.

The traces from the radiation measurement devices indicated that most of the fissions occurred in the first 2.8 min, in which case the average power required for the observed fission yield was approximately 220 kW. After the first 2.8 min the system was postulated to have boiled causing a sharp decrease in density and reactivity of the system. This boiling probably reduced the power output from the system to a low level for the final 18 min of the excursion. This paper will aim to investigate the subsequent evolution of the Y12 excursion using the fundamentally based spatially dependent neutron/multiphase CFD kinetics simulation tool - FETCH. The reconstruction of the Y12 excursion using FETCH will follow the evolution of the excursion up until the uranyl nitrate starts to boil. The results of the FETCH simulation are presented and compared against the known measurements of the excursion from the radiation detection instruments located near the drum.
Original languageEnglish
Pages (from-to)12-21
Number of pages10
JournalProgress in Nuclear Energy
Volume63
DOIs
Publication statusPublished - Mar 2013

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Radiation
kinetics
Kinetics
Nitrates
nitrate
Solid wastes
Uranium
solid waste
Boiling liquids
simulation
accident
Accidents
Neutrons
Computational fluid dynamics
oak
analysis
radiation
Water
water
enriched uranium

Keywords

  • criticality accident modelling
  • criticality accident
  • radiation transport
  • computational multi-phase dynamics
  • coupled radiation fluid physics

Cite this

Simulated spatially dependent transient kinetics analysis of the Oak Ridge Y12 plant criticality excursion. / Buchan, Andrew (Corresponding Author); Pain, Christopher; Tollit, Brendan; Gomes, Jefferson L. M. A.; Eaton, Matthew D.; Gorman, Gerard J.; Cooling, Christopher; Goddard, Anthony J.H.; Nygaard, Erick T.; Angelo, Peter L.; Smith, Paul N.

In: Progress in Nuclear Energy, Vol. 63, 03.2013, p. 12-21.

Research output: Contribution to journalArticle

Buchan, A, Pain, C, Tollit, B, Gomes, JLMA, Eaton, MD, Gorman, GJ, Cooling, C, Goddard, AJH, Nygaard, ET, Angelo, PL & Smith, PN 2013, 'Simulated spatially dependent transient kinetics analysis of the Oak Ridge Y12 plant criticality excursion', Progress in Nuclear Energy, vol. 63, pp. 12-21. https://doi.org/10.1016/j.pnucene.2012.09.006
Buchan, Andrew ; Pain, Christopher ; Tollit, Brendan ; Gomes, Jefferson L. M. A. ; Eaton, Matthew D. ; Gorman, Gerard J. ; Cooling, Christopher ; Goddard, Anthony J.H. ; Nygaard, Erick T. ; Angelo, Peter L. ; Smith, Paul N. / Simulated spatially dependent transient kinetics analysis of the Oak Ridge Y12 plant criticality excursion. In: Progress in Nuclear Energy. 2013 ; Vol. 63. pp. 12-21.
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N2 - In June 1958 an accidental nuclear excursion occurred in the C-1 Wing of building 9212 in a process facility designed to recover enriched Uranium U(93) from various solid wastes. The accident was caused by the inadvertent flow of enriched uranyl nitrate into a 55 gallon drum which established a prompt critical nuclear excursion. Following the initial fission spike the nuclear system oscillated in power. The reaction was eventually terminated by the additional water which was flowing into the drum. The criticality excursion was estimated to have lasted approximately 20 min based upon nearby radiation measurement equipment with an estimated total fission yield of 1.3 × 1018 fissions of which the first fission spike contributed 6 × 1016 fissions. The traces from the radiation measurement devices indicated that most of the fissions occurred in the first 2.8 min, in which case the average power required for the observed fission yield was approximately 220 kW. After the first 2.8 min the system was postulated to have boiled causing a sharp decrease in density and reactivity of the system. This boiling probably reduced the power output from the system to a low level for the final 18 min of the excursion. This paper will aim to investigate the subsequent evolution of the Y12 excursion using the fundamentally based spatially dependent neutron/multiphase CFD kinetics simulation tool - FETCH. The reconstruction of the Y12 excursion using FETCH will follow the evolution of the excursion up until the uranyl nitrate starts to boil. The results of the FETCH simulation are presented and compared against the known measurements of the excursion from the radiation detection instruments located near the drum.

AB - In June 1958 an accidental nuclear excursion occurred in the C-1 Wing of building 9212 in a process facility designed to recover enriched Uranium U(93) from various solid wastes. The accident was caused by the inadvertent flow of enriched uranyl nitrate into a 55 gallon drum which established a prompt critical nuclear excursion. Following the initial fission spike the nuclear system oscillated in power. The reaction was eventually terminated by the additional water which was flowing into the drum. The criticality excursion was estimated to have lasted approximately 20 min based upon nearby radiation measurement equipment with an estimated total fission yield of 1.3 × 1018 fissions of which the first fission spike contributed 6 × 1016 fissions. The traces from the radiation measurement devices indicated that most of the fissions occurred in the first 2.8 min, in which case the average power required for the observed fission yield was approximately 220 kW. After the first 2.8 min the system was postulated to have boiled causing a sharp decrease in density and reactivity of the system. This boiling probably reduced the power output from the system to a low level for the final 18 min of the excursion. This paper will aim to investigate the subsequent evolution of the Y12 excursion using the fundamentally based spatially dependent neutron/multiphase CFD kinetics simulation tool - FETCH. The reconstruction of the Y12 excursion using FETCH will follow the evolution of the excursion up until the uranyl nitrate starts to boil. The results of the FETCH simulation are presented and compared against the known measurements of the excursion from the radiation detection instruments located near the drum.

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