Tuesday, March 15, 2011

Post # 31: BWR Station Blackout Severe Accidents - Primer Documents

My heart goes out to the Japanese people who are dealing with an overwhelming natural disaster that has resulted in the death of thousands and the destruction of untold billions of dollars in property and infrastructure.   Like almost everyone else, I've been watching the unfolding events at Japan's Fukushima Dai-ichi plant with a mixture of horror and admiration for the heroic efforts of the plant staff to contain and terminate the accident progression in Units 1-4.

Many of you know I've spent my career at Oak Ridge National Laboratory.  I've been at ORNL since 1978.  From 1980 through the late 1990s, ORNL had a pioneering program in the investigation of severe accidents in boiling water reactors or "BWRs". This work was primarily funded by the U.S. Nuclear Regulatory Commission.   During the almost twenty years of research at ORNL, the Lab produced a large number of reports, journal articles, and professional society presentations on the accident progression and phenomenology of beyond-design-basis severe or "core melt" accidents in BWRs.  During that period, we utilized several U.S. BWR plants as our reference plants for analysis.  These include the Browns Ferry and Peach Bottom (BWR-4/Mk-I) plants, Limerick (BWR-4/Mk-II), and Grand Gulf (BWR-6/Mk-III) plants.

In light of the on-going events at Fukushima, and with an eye toward the inevitable re-examination of such accidents this event will catalyze, I thought I would post here an extremely abbreviated bibliography of ORNL publications relevant to Fukushima's station blackout severe accident and related reactor building hydrogen deflagration/detonation phenomena.

Some critical words of caution regarding applicability of the analyses referenced below to Fukushima:

1. The Fukushima Dai-ichi units were NOT analyzed.  My understanding is that Fukushima Dai-ichi #1 is a BWR-3 / Mark I containment system.  (The alternative nomenclature "MK-I" is often used).  Units 2,3, and 4 are BWR-4 / Mark I plants.  As previously mentioned, the reference plants used in the analyses below were U.S. BWR-4/MK-I plants.

2. The "station blackout" accidents analyzed in these reports began with the assumption that: (1) all off-site AC power was lost, (2) the diesel generators were unavailable to provide backup AC power, and (3) the station batteries were available to provide DC power until the batteries were exhausted.  According to all available accounts, these three head-end events appear to have occurred at Fukushima. HOWEVER, the HUGH difference in the scenarios analyzed below and last week's event is that the historical analyses did not include an earth quake and tsunami as the "top events".  Thus any damage from these two natural events that may have occurred at Fukushima is not accounted for in the analyses reference below.

3. Some of the sequences referenced below assume specific plant operator responses that may or may not be applicable to the Fukushima events.

So, similar reactors and containments, and similar top events BUT caveat, caveat, caveat...

  • NUREG/CR-2182, Vol 1, Station Blackout at Browns Ferry Unit One – Accident Sequence Analysis, D. H. Cook, S. R. Greene, R. M. Harrington, S. A. Hodge, D. D. Yue,  November 1981
  • NUREG/CR-2182, Vol 2, Station Blackout at Browns Ferry Unit One – Iodine and Noble Gas Distribution and Release, R. P. Wichner et al.,  August 1982
  • NUREG/CR-2973, Loss of DHR Sequences at Browns Ferry Unit One – Accident Sequence Analysis, D. H Cook, S. R. Greene, R. M. Harrington, and S. A. Hodge, May 1983
  • NUREG/CR-2940,  Realistic Simulation of Severe Accidents in BWRs – Computer Modeling Requirements, S. R. Greene, April 1984
  • NUREG/CR-3617, Noble Gas, Iodine, and Cesium Transport in a Postulated Loss of Decay Heat Removal Accident at Browns Ferry, R. P. Wichner, et al., August 1984
  • NUREG/CR-5317, Primary Containment Rsponse Calculations for Unmitigated Short-term Station Backout at Peach Bottom, S. A. Hodge, C. R. Hyman, L. J. Ott, 
  • NUREG/CR-5565, The Response of BWR Mark II Containment to Station Blackout Severe Accident Sequences,  S. R. Greene, S. A. Hodge, C. R. Hyman, M. L. Tobias,  May 1991
  • CONF-8310143-11, BWR Severe Accident Sequence Analyses at ORNL – Some Lessons Learned, S. A. Hodge, 11th Water Reactor Safety Information Meeting,  Oct. 25, 1983
  • CONF-8410142--85, Fission Product Transport Analysis In A Loss Of Decay Heat Removal Accident At Browns Ferry, R. P. Wichner et al., 12th Water Reactor Safety Information Meeting, Oct 23, 1984
  • CONF-871011--6, The Impact of BWR MK-I Primary Containment Failure Dynamics on Secondary Containment Integrity,  S. R. Greene, 15th Water Reactor Safety Information Meeting,  Oct 29, 1987
  • CONF-890546--1, Thermalhydraulic Processes In The Reactor Coolant System of A BWR Under Severe Accident Conditions, S. A. Hodge, Jan 1 1989 
  • CONF-9104223--1, Identification and Initial Assessment of Candidate Late-Phase In-Vessel Accident Mitigation Strategies, S. A. Hodge, April 1991
  • Nuclear Engineering and Design, Vol 120, Issue 1, 1 June 1990, Pages 75-86, The Role of BWR Secondary Containments In Severe Accident Mitigation: Issues and Insights From Recent Analyses, S. R. Greene
  •  Nuclear Engineering and Design, Vol 148, Issue 2-3, Pages 185-203, July 1994, Assessment of Two BWR Accident Management Strategies, S. A. Hodge

Some nice accident analysis work was also done at other National Labs during the period.  One particularly-relevant analysis out of Brookhaven National Laboratory:

  • NUREG/CR-5850,  Analysis of Long-Term Station Blackout Without Automatic Depressurization at Peach Bottom Using MELCOR (Version 1.8), I. K. Madni, May 1994

The major  universities also produced some relevant analysis work.  Here's one from the University of Tennessee,

  • Matthew Wesley Francis, Long-Term Station Blackout Sequence and Mitigation MELCOR Model, A Thesis Presented for the Master of Science Degree, May 2006

Finally, I would also recommend as a general primer on light water reactor severe accident phenomena

Over the next several days, I will expand this list and attempt to add URL pointers to the document.  In the mean time, I believe all or almost all of these documents are available through the DOE OSTI Information Bridge @ http://www.osti.gov/bridge , or at online journal archive sites such as ScienceDirect @ http://www.sciencedirect.com/.  A diligent google search should turn them up.


No comments:

Post a Comment