Page 42 - July-August 2012
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42
Nuclear Plant Journal, July-August 2012
Nuclear Power...
with flood and seismic and then
expanding to broader areas including
high winds, low temperatures, and
loss of ultimate heat sink.
Developmentofmodelsandanalytical
•
methods for thermo hydraulic issues
with the spent fuel pool (boil-off time,
condensation effects, uncovered fuel,
dose modeling, and other analyses)
to develop SAMGs for spent fuel
pools.
Characterization of the radiological
•
releases for use in improving
emergency response.
Verify Readiness for
Known Conditions
The first step of the US response was
to verify readiness for known or potential
conditions. Our goal was to verify:
Station Black out strategies
•
B.5.b. security order
•
SAMG equipment
•
Flooding Protective Functions
•
Flooding/Fire Impacted by Seismic
•
We also performed a review of
preventive
maintenance
strategies,
configuration control, training, and
inspections and established additional
operational controls for spent fuel pools.
Improve
Countermeasures
Guidance was developed to address
an extended loss of all AC power. We
wanted to understand the challenges
and establish measures to extend critical
safety functions.
The US industry also adapted a
diverse and flexible coping strategy.
We call this “FLEX.” Flex provides an
additional layer of defense in depth for
beyond design basis accidents.
Our goal is that the new Industry
Event Response will become an efficient
leverage of industry capabilities to aid the
affected station.
Guidance for loss of
power
We established guidance for a given
set of conditions- total loss of AC power
for > 24 hours with a focus to:
Retain distribution
•
Retain DC
•
The US industry is working with
EPRI to develop a study with action
that can be implemented while awaiting
a longer-term solution. The study
includes:
Determine limiting conditions
•
Determine next steps to extend
•
coping time
Determine how other similar plants
•
differ in approach
Procedural strategies are being
developed for the critical safety and to
maintain functions. This leads into the
Diverse/Flexible coping strategy.
Diverse Flexible
Response Strategy
Flex is a long-term strategy designed
to protect core cooling, spent fuel pool
cooling and containment inventory.
We recognize, we cannot predict all
means that can challenge critical safety
functions, but we can develop strategies
to preserve critical safety functions and
support monitoring.
Flex relies on diverse equipment
protected from hazards. It’s a flexible
strategy recognizing variability in the
initiating event. The FLEX approach has
three phases,
Each site performs site analysis for
•
site specific hazards
Specifications
for
equipment
•
procurement are developed,
Periodic surveillance for quality,
•
maintenance, and testing are
provided.
Three Phase Approach
for FLEX
Phase 1 relies on the use of already
installed equipment. Phase 2 involves
the use of installed and on-site portable
equipment such as generators, extra
batteries, low head pumps. Finally, phase
3 involves the use of offsite equipment,
transported from remote storage facilities
located in different regions of the United
States. These will add diversity and
continuity of critical safety functions.
Equipment Acquisitions
Nearly400equipment purchases have
been made or arranged. All US utilities
have committed to order equipment by
March 2012 that will be compatible with
the future implementation of FLEX.
About 40% of identified equipment is on-
site and 82% will be on-site by the end
of 2012.
Off-site Equipment
Support
The US industry is moving forward
to establish off-site centers for staging of
equipment for emergency response. This
phase is looking to:
Define equipment
•
Logistics
•
Government support, as necessary
•
Central accountability for the line of
•
sight support.
The key objective is to extend critical
safety functions indefinitely.
Industry Technical
Support
In order to provide industry technical
support during severe accidents, the US
industry plans to have experts in multiple
areas designated by name. We have
learned from our experiences during the
first week after the Fukushima accident
with the utility TEPCO. The US industry
established a team at TEPCO with a
shadow team in Atlanta at the WANO/
INPO offices. We handled several
hundred requests over a 9 month period.
However, it took too long to be effective
in light of the required time frame.
Our goal under FLEX is to setup
a comprehensive emergency response
organization within 24 hours, including:
NRC interaction
•
Utility support
•
Vendor support
•
National lab support
•
Implementation Status
Nearly 190 man-years have been
applied to responding to the Fukushima
accident.
We now have a US Industry
response strategy approved and in
place. Equipment acquisitions, plant
modifications, procedure changes are
