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NuclearPlantJournal.com Nuclear Plant Journal, May-June 2015
including seismic, flooding, high winds,
high heat and low, extreme cold. That’s
the permanent installed equipment. It
should be protected against that. Then
the portable equipment is stored basically
away from the power block of the plant,
but it’s stored in a location that’s also
protected against all those hazards. The
third phase is equipment being brought
from a national response center (SAFER).
The two redundant response centers are
located in Memphis, Tennessee, and in
Phoenix, Arizona. They have sufficient
equipment that if four units were affected
simultaneously, that equipment could be
brought in, and it’s basically staged. It’s
brought to a location that’s between 25
and 35 miles away from the site. The
reason for that is 25miles allows sufficient
distance from the site, recognizing that
would probably be the area affected by
the disaster or whatever, but within 35
miles so the equipment can be brought in
via a heavy-lift helicopter if necessary.
All of the equipment is basically
locally operated. It’s locally controlled.
The hookup and the operations of
the equipment is very simplified. So,
there is little to no reliance on other
systems in order to operate the portable
equipment. It’s basically the systems that
are necessary are shown to be protected,
and that’s it. It doesn’t matter what the
impact is to the rest of the plant. The
newly added equipment is available in
any one of these events.
Jack Davis
: Part of our request for
information would show us, you have
communications equipment suitable to
take care of the situation, which would also
allow a site to talk to an off-site Technical
Support Center (TSC) or EOC (Emergency
Operation Center). You’re already doing
that as part of mitigation strategies.
Jeremy Bowen
: Plants had to verify
that they have adequate communications
for a multisite event, and that includes
communications on-site to implement all
these strategies, and then communications
off-site.
The mitigating strategies and
procedures in place in addition to
what we’ve had previously, allow us
communications, allows instrumentation
to be read remotely and so on, so that you
can execute the strategy no matter what
you’ve lost on-site.
Jeremy Bowen:
The strategies are
flexible and diverse such that there’s multiple
ways to do any one given activity. So, there’s
multiple ways to read instrumentation
information, and there’s backups.
4.
How are the current requirements for
seismic hazard evaluations different as
compared to what the plant has already
been designed, and where are we getting
all this new data? Are there federal
agencies which are monitoring all the
seismic events since the time the plant
was built?
Jeremy Bowen:
You have a design
basis that you have to address certain
hazards. Seismic and flooding are two
of those hazards. There are others, high
winds being an example. As part of
that, there’s always any time the agency
gets new information, it evaluates how
to process that information through the
regulatory structure and decides what to
do with it, whether to make changes to the
license or impose additional requirements
on licensees.
For seismic, the U.S. Geological
Survey in the 2009 time frame basically
reevaluated the seismic potential for the
Central and Eastern United States. And
that information was already starting to
go into the process, what does that mean
for nuclear power plants? How do we
evaluate that? Now after Fukushima
happened, and it was basically that was
all rolled together, and the decision was
made to issue this 50.54(f) letter, request
for additional information, and ask
licensees to take that 2009 data and look
at it compared to their existing design
basis safe shutdown earthquake and their
design basis seismic events and look if
there is any change based on this new
information in 2009. All of the Central
and Eastern U.S. plants submitted their re-
evaluations in March 2014, and the three
Western plants submitted it on March 12,
2015. And now the agency is taking that
information and moving forward, what’s
the next step? Many of the licensees,
where there was significant change
between what their design basis was
and what the new information showed,
they’re doing what are called seismic
PRAs (Probabilistic Risk Assessment).
So, you’re looking at the impact of that
event on all the components in the plant,
and that will help inform the agency and
the licensees, whether any changes are
necessary to the plant.
In the meantime, to allow us time
to do that, the industry did what’s called
an expedited seismic evaluation process
review. Plants with a higher new hazard
basically looked at the mitigating
strategies equipment, the phase 1 installed
equipment and the connections for the
portable phase 2 equipment, and verified
that that equipment is sufficient, that it
can sufficiently handle the new seismic
hazard, while there’s time to go do a more
thorough, in-depth look at all of the plant
equipment through the seismic PRA. The
first seismic PRAs are supposed to come
in the 2017 time frame.
A very similar process is being
done for flooding. Basically, there’s
newer modeling techniques, additional
information that’s, 30, 40, 50 more years’
worth of storm data being applied to these
newer, updated models to see if it would
result in a different amount of water on
the site. If there is, if that does indicate
a different amount of water on the site,
then how would the site cope with that?
What activities would you employ, or if
any changes are necessary to the plant?
There was an interim action taken where
the sites did a walk-down of all their
equipment to make sure there weren’t
any concerns with their current flooding
protection on-site.
Jack Davis:
Currently for the
reevaluation for flooding and seismic,
every plant has interim actions in place
that the agency has reviewed to ensure
that’s acceptable while they take the longer
time to do the thorough review. And then
if there needs to be any changes, that’s
a future decision that the Commission
would have to make right through
backfitting. The Commission will make a
determination whether any of the design
bases of these plants needs to change. But
safety is assured now to buy the time to do
that more thorough review and figure out
where we want to be with these plants.
5.
Howare the utilities doing in completing
their Fukushima related modifications
submittals before the deadline?
Fukushima
Lessons...
