The Risk, Reality and Future of Nuclear Power
Gregory Jaczko
April 17, 2015
The Risk, Reality, and Future of Nuclear Power
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Overview
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Risk
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Qualitative Health Objectives
Reality
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Why Nuclear Power is Still Around
Fukushima Accident
Future
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Industry fading in the United States
Overview
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Energy and
electricity play an
increasingly
important role in
our lives
•
Energy use is
expected to grow
over the next
several decades
Overview
Source: METI Energy Outlook
Overview
•
The nuclear power industry remains a viable electricity option today
for three basic reasons:
1. countries wish to keep open the option to develop a nuclear
weapons program
2. countries wish to have a fuel diversity among their energy options
or lack their own supplies and fossil imports are expensive
3. countries wish to abate air pollution, especially carbon dioxide
➡
especially true in the United States
Risk: What is Safety
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Safety: freedom from the occurrence of injury, danger, or loss.
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Safety is a completely subjective determination
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safety decision are influenced by public policy, government,
science and culture
Frustrations with the treatment of nuclear power by the citizens
groups and the media led to the creation of a new method for
comparing the relative hazards of different activities
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this is what we call risk assessment
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perceived by many to be an objective determination of safety
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IT IS NOT
Risk: Risk and Safety
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risk: exposure to the chance of injury or loss
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generally thought of as
risk = probability X consequence
measured in units of hazard/time
==> a number, so it is believed to be objective
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better definition is the so-called risk triplet
1. what can go wrong?
2. how likely is it?
3. what are the consequences?
does NOT give you a single number, but a range of answers
Risk: Enhanced Use of PRA
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following the three miles island accident in 1979 substantial
recommendations were made to:
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enhance the NRC’s understanding of accident hazards and
causes
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increase the use of probabilistic risk analysis to complement
deterministic approaches to safety assessment
the led to
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safety goal policy statement, define acceptable level of power
reactor risk
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NUREG-1150, updated analysis comparable to WASH-1400
Risk: Safety Goal Policy Statement
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Published in 1986 as a policy statement
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not a regulation, so it is not binding legally, but provides
perspective
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Two forms of the safety goals
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qualitative health objectives
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quantitative health objectives
REMEMBER, goal is to try and find an objective way to
talk about safety (but that is impossible)
Risk: Qualitative Health Objectives
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Qualitative
1. “Individual members of the public should be provided a
level of protection from the consequences of nuclear power
plant operation such that individuals bear no significant
additional risk to life and health”
2. “Societal risks to life and health from nuclear power plant
operation should be comparable to or less than the risks of
generating electricity by viable competing technologies and
should not be a significant addition to other societal risks.”
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not very useful for decision making, so created a quantitative
set
Risk: Quantitative Health Objectives
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Quantitative
1. “The risk to an average individual in the vicinity of a nuclear
power plant of prompt fatalities that might result from reactor
accidents should not exceed one-tenth of one percent (0.1
percent) of the sum of prompt fatality risks resulting from other
accidents to which members of the U.S. population are
generally exposed”
2. The risk to the population in the area near a nuclear power
plant of cancer fatalities that might result from nuclear power
plant operation should not exceed one-tenth of one percent
(0.1 percent) of the sum of cancer fatality risks resulting from
all other causes.”
Risk: Health Objectives
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Things to keep in mind
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even the qualitative are not useful for actual decision-making
—> use of surrogate measures
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core damage frequency
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large early release frequency (or large release
frequency)
these do not cover economic impacts of operation or other
societal damage such as land contamination or habitat
destruction
Risk: Core Damage Frequency
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Average CDF value for U.S. plants is about 2 x 10^(-5) /
plant /year
—> for about 100 plants, chance of a reactor accident is about
1 every 500 years
—> for about 500 plants worldwide, chance of a reactor accident is about
1 every 100 years
—> for about 50% percent of global electricity production with todays
consumption you need 4 times as many plants, chance of reactor accident
1 every 25 years
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Is that acceptable to society when it happens?
Reality: Fukushima Daiichi Accident
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A 9.0 magnitude earthquake
occurred off the coast of
Japan on March 11, 2011
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The earthquake triggered a
tsunami which directly
impacted four nuclear plant
sites in Japan
Reality: Fukushima Accident
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Tsunami
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several tsunami waves were triggered by the earthquake
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one of the waves was approximately 14 meters high, about 50 feet
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this led to site flooding at about 13 feet
Fukushima Accident
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The primary issue was a loss of all power to and on the site
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the earthquake disabled bulk power transmission to the
site
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the flooding and impact of the tsunami disabled the
backup system and internal power distribution
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diesel generators were lost —> power to motors for
pumps and valves were lost
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batteries were lost —> no lights and no
instrumentation
Fukushima Daiichi Accident
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Hydrogen explosion in Unit 1 really set the plant on a path
to severe accident
Reality: Fukushima Accident
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Within approximately 1 hour station blackout
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Unit 1
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within hours loss of cooling and core uncovered
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with about a day, hydrogen explosion eliminates possibility to recover unit 1
Unit 2
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about 3 days after tsunami, water level below top of active fuel
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explosion about 3 1/2 days later indicating loss of pressurization in unit 2
Unit 3
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about 2 days after tsunami, water level below top of active fuel
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about 3 days after tsunami, hydrogen explosion
Unit 4
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about 3 1/2 days later hydrogen explosion
Reality: Fukushima Accident - US Response
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There were two primary issues the NRC and US government were
concerned about
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extent of radiation contamination —> 50 mile recommendation
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the condition of the spent fuel pools
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significant contamination of land around the reactor sites
spent fuel fires can cause widespread contamination
possible evacuation of Tokyo - an unthinkable scenario
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was it possible?
some in Japan thought so…
Reality: Fukushima Accident — Impact
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Human toll — more than 100,000 people evacuated
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All nuclear plants shutdown — 30% of Japan’s electricity generating capacity
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Cleanup of Daiichi will continue for decades
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Water management
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Spent fuel removal
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Decontaminations
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Relocations?
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Melted fuel removal
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Decommission existing reactors
Reality: Fukushima Accident Impact
"The current rough estimate of the total cost to Japan from the
Fukushima Dai-ichi accident is about $500 billion U.S. dollars, which
will substantially increase if nuclear electricity generation continues
to be replaced for a long time by other means."
-- "Forging a New Nuclear Safety Construct, ASME 6/14/2012
Reality: Fukushima Accident — Safety Policy
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Remember the health objectives?
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The risk to an average individual in the vicinity of a nuclear power
plant of prompt fatalities that might result from reactor accidents
should not exceed one-tenth of one percent (0.1 percent) of the
sum of prompt fatality risks resulting from other accidents to
which members of the U.S. population are generally exposed.
•
The risk to the population in the area near a nuclear power plant
of cancer fatalities that might result from nuclear power plant
operation should not exceed one-tenth of one percent (0.1
percent) of the sum of cancer fatality risks resulting from all other
electricity sources
Is this the right approach?
Reality: Preparedness is Weak
Emergency Preparedness
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No single government authority in the United States or Japan has
authority over nuclear power plant safety and emergency
preparedness
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Local governments vital to the process
Fukushima showed weakness in Japanese system and
weaknesses in US system
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Never considered multiple reactors at one time
Must have involvement of all levels of government
Reality: What Safety should be
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After Fukushima, Safety must mean:
No accident can EVER require evacuation of anyone outside
the plant
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This is not a probabilistic statement
Future
Future: License Renewal — Why
Fuel as a Percent of Production Costs
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Cost to operate nuclear power
plants is generally low
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Without major upgrades to
equipment and other capital
costs, license extension is a
very inexpensive way to “add”
additional electricity capacity
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Every plant that has not shut down or planned to
shutdown will apply or has applied for a license extension
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Over 73 reactor license extensions have been approved
Future: License Renewal
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“Life after 60” or “Subsequent license extension”
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Unclear at this point whether there will be any plants seeking an additional
extension
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NRC staff is currently expressing doubt about using the existing process
60 or more years of operation will begin to challenge safety assumptions
about major components such as concrete for containment and pressure
vessel
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The Atomic Energy Act places no limitations on the number of license
extensions a plant may apply for
begins to undermine the economic arguments for license renewal
5 years ago there was great confidence in a subsequent renewal
Future: New Reactors
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There are currently 4 newly licensed reactors under construction in
the U.S.
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2 at the Vogtle plant site in Georgia
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2 at the V.C. Summer plant site in South Carolina
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Both plants are using the AP1000 design by Westinghouse
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First new licenses issued under the new combined license process
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Major test for future of nuclear — plants need to be built on time
and on budget
Future: Recent Closures
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There have been a number of recent or planned plant
closures
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Vermont Yankee due to economic considerations
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Kewaunee due to economic considerations
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San Onofre unit 2 and 3 due to safety concerns
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Crystal River due to safety concerns
Future: New Reactors — III+
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These plants employ a number of new features (but not new ideas)
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Passive emergency cooling systems
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Modular construction
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less reliance on electrical systems for cooling during the initial
period of an accident
allows Lego-like construction process to make the fabrication
of the plant quicker, cheaper and more predictable
But they do not meet the new concept for safety — severe
accidents are still possible
Future: New Reactors
Future: New Reactors — Status
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To truly spur a nuclear revival, Vogtle and V.C. Summer needed to
be built without a doubt on time and on budget
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How are they doing?
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Vogtle is at least 3 years behind schedule with $1.5 billion in
cost overruns
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problems were largely the result of modular construction
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Vogtle 3 is expected to come online in 2019
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Vogtle 4 one year later
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V.C. Summer is similarly behind schedule and over budget
Future: Best Case Scenario in US right now
Conclusion
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Risk has proven to be a useful tool for analysis, but not a meaningful tool for policy decisions
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The reality of accidents does not lend itself to probabilistic risk approaches
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Fukushima is the prime example of this phenomenon
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During an accident the probability is 1
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And the consequences are real
Only societally acceptable safety standard is not risk based:
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No offsite consequences from an accident
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These challenges will not be solved with a new generation of plants in the United States
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Only really designing plants that can meet the new standard will be possible in the long run
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No large containments, no redundant safety systems —> cheaper, faster construction
Absent new approaches, nuclear will eventually phase out in the United States