Date: May 20, 2016
FOR IMMEDIATE RELEASE
Fukushima Daiichi Nuclear Accident Is ‘Wake-Up Call’ for U.S. to Improve Real-Time Monitoring of Spent Fuel Pools
WASHINGTON
– The 2011 Fukushima Daiichi nuclear accident should serve as a wake-up
call to nuclear plant operators and regulators on the critical
importance of measuring, maintaining, and restoring cooling in spent
fuel pools during severe accidents and terrorist attacks, says a new
report from the National Academies of Sciences, Engineering, and
Medicine. This report is the second and final phase of a
congressionally mandated study on what lessons can be learned from the
Fukushima Daiichi nuclear accident. The report from Phase 1 of this study was released in July 2014. The Phase 2
report provides findings and recommendations for improving U.S. nuclear
plant security and spent fuel storage as well as re-evaluates
conclusions from previous Academies studies on spent fuel storage safety and security.
The
committee that carried out the study and authored the Phase 2 report
found that spent fuel storage facilities -- both spent fuel pools used
to store fuel under water and casks used to dry-store fuel -- at the
Fukushima Daiichi nuclear plant maintained their containment functions
during and after the March 11, 2011, Great East Japan Earthquake and
tsunami. However, one of the two gates separating the Unit 3 spent fuel
pool from the adjacent reactor well was damaged during the accident.
Also, water appeared to have leaked around the gate seals in the Unit 4
spent fuel pool, allowing water to flow into the pool from the reactor
well.
This
water leak was accidental but also fortuitous, because it replenished
water lost from the Unit 4 pool by evaporation, likely preventing water
levels from dropping to the tops of the racks where the spent fuel was
being stored. Keeping the fuel covered with water is essential for
cooling and radiation shielding. Uncovery of the fuel would have
substantially increased radiation levels above and around the pool,
limiting personnel access to the pool and nearby areas, and could have
resulted in severe damage to the fuel, increasing the potential for
large radioactive material releases into the environment.
The
committee recommended that the U.S. nuclear industry and the U.S.
Nuclear Regulatory Commission (USNRC) improve the ability of plant
operators to measure real-time conditions in spent fuel pools and
maintain adequate cooling of stored spent fuel during severe accidents
and terrorist attacks. These improvements should go beyond the current,
post-Fukushima response to include hardened and redundant physical
surveillance systems such as cameras, radiation monitors, pool
temperature and water-level monitors, and means to deliver makeup water
or sprays to the pools, even when physical access is limited by facility
damage or high radiation levels.
Extreme
external events and severe accidents can cause widespread and
long-lasting disruptions to security infrastructure, systems, and
staffing at nuclear plants, the committee concluded. Such disruptions
can create opportunities for malevolent acts and increase the
susceptibility of critical plant systems to such acts. Therefore, the
committee recommended, nuclear plant operators and their regulators
should upgrade and/or protect nuclear plant security infrastructure and
systems and train security personnel to cope with extreme external
events and severe accidents. Such upgrades should include redundant and
protected power sources dedicated to plant security systems that
function independently if safety systems are damaged, as well as diverse
and flexible approaches for coping with and reconstituting plant
security infrastructure, systems, and staffing during and following
extreme external events and severe accidents.
The
committee determined that the USNRC has implemented most of the
recommendations from previous Academies reports on spent fuel safety and
security. However, two recommendations from those reports have not yet
been implemented, the committee found. The first was to analyze the
vulnerabilities of spent fuel pools to specific terrorist attack
scenarios described in the 2004 Academies report,
and the second was to carry out an independent examination of
surveillance and security measures for protecting stored spent fuel.
This independent examination should address the effectiveness of the
USNRC’s security and surveillance measures for addressing the insider
threat, the committee said. It also recommended that the USNRC and
nuclear industry strengthen their capabilities for identifying,
evaluating, and managing the risks from terrorist attacks and that the
USNRC sponsor a spent fuel storage security risk assessment of
sufficient scope and depth to explore the benefits of this methodology
for enhancing security at U.S. nuclear plants.
The
committee reviewed technical analyses carried out by the USNRC to
inform a regulatory decision on whether to expedite the transfer of
spent fuel from pools to dry casks to reduce storage risks. Although
these analyses are valuable technical contributions to understanding the
consequences of spent fuel pool accidents, they are of limited use for
assessing spent fuel storage risks because they do not consider sabotage
risks, dry cask storage risks, or certain health consequences that
would likely result from a severe nuclear accident. It is also
difficult to make valid comparisons between pool and dry cask storage
risks because of the way the analyses were carried out. The committee
recommended that the USNRC perform a spent fuel storage risk assessment
that addresses both accident and sabotage risks for both pool and dry
cask storage. USNRC staff informed the committee that it is already
thinking about how to expand its risk assessment methodologies to
include sabotage risks.
The
study was sponsored by the U.S. Nuclear Regulatory Commission. The
National Academies of Sciences, Engineering, and Medicine are private,
nonprofit institutions that provide independent, objective analysis and
advice to the nation to solve complex problems and inform public policy
decisions related to science, technology, and medicine. The Academies
operate under an 1863 congressional charter to the National Academy of
Sciences, signed by President Lincoln. For more information, visit http://national-academies.org.
Contacts:
Jennifer Walsh, Senior Media Relations Officer
Emily Raschke, Media Relations Assistant
Office of News and Public Information
202-334-2138; e-mail news@nas.edu
Twitter: @theNASEM
Copies of Lessons Learned From the Fukushima Nuclear Accident for Improving Safety and Security of U.S. Nuclear Plants: Phase 2 are available from the National Academies Press on the Internet at http://www.nap.edu or
by calling 202-334-3313 or 1-800-624-6242. Reporters may obtain a copy
from the Office of News and Public Information (contacts listed
above). A committee roster follows.
THE NATIONAL ACADEMIES OF SCIENCES, ENGINEERING, AND MEDICINE
Division on Earth and Life Studies
Nuclear and Radiation Studies Board
Committee
on Lessons Learned from the Fukushima Nuclear Accident for Improving
Safety and Security of U.S. Nuclear Plants: Phase 2
Joseph E. Shepherd (chair)
Vice President for Student Affairs, and
C.L. "Kelly" Johnson Professor of Aeronautics and Professor of Mechanical Engineering
California Institute of Technology
California Institute of Technology
Pasadena
Robert A. Bari
Senior Physicist
Brookhaven National Laboratory
Upton, N.Y.
Jan Beyea
Chief Scientist
Consulting in the Public Interest
Lambertville, N.J.
Michael L. Corradini*
Professor
Department of Engineering Physics
University of Wisconsin-Madison
Vijay K. Dhir*
Distinguished Professor of Mechanical and Aerospace Engineering
Mechanical and Aerospace Engineering Department
University of California, Los Angeles
Michael W. Golay
Professor of Nuclear Science and Engineering
Department of Nuclear Science and Engineering
Massachusetts Institute of Technology
Cambridge
Barbara L. Hamrick
Radiation Safety Officer
University of California, Irvine Medical Center
Paul A. Locke
Associate Professor
Department of Environmental Health Sciences
Johns Hopkins Bloomberg School of Public Health
Baltimore
Thomas G. Moser
Independent Consultant
Wilmington, N.C.
Arthur T. Motta
Chair, Nuclear Engineering Program, and
Professor of Nuclear Engineering and Materials Science Engineering
Pennsylvania State University
University Park
John A. Orcutt*
Distinguished Professor of Geophysics
Scripps Institute of Oceanography
University of California, San Diego
La Jolla
Emilie M. Roth
Owner and Principal Scientist
Roth Cognitive Engineering
Menlo Park, Calif.
Elizabeth Q. Ten Eyck
President
ETE Consulting, Inc.
Great Falls, Va.
Frank N. von Hippel
Senior Research Physicist and Professor of Public and International Affairs Emeritus
Program on Science and Global Security
Princeton University
Princeton, N.J.
Loring A. Wyllie Jr.*
Chairman Emeritus of the Board, and
Senior Principal
Degenkolb Engineers
San Francisco, Calif.
STAFF
Kevin D. Crowley
Study Director
_________________________________________
* Member, National Academy of Engineering
http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=21874
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