Nuclear Plant Journal, January-February 2016 NuclearPlantJournal.com
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possible mitigation strategies (FLEX)
in various buildings, compartments and
containment. The accurate GOTHIC
pressure and temperature results assure
that technically appropriate and correctly
timed actions and modifications are
implemented and that unnecessary plant
or procedure changes are eliminated.
GOTHIC’s capability to account for
transient heat transfer in the determination
of equipment/component temperatures
often provided additional margin to
temperature limits.
GOTHIC has also been utilized
to determine the hydrodynamic loads
produced by fuel pool water waves/
oscillations on equipment in and above
the pool during beyond design basis
seismic events. That required a minor
change to GOTHIC that has since been
incorporated in the new version of
GOTHIC to be released in late 2016.
Improvements have also been made to
the radiation heat transfer modeling to
improve capabilities for simulating spent
fuel heat up and oxidation.
GOTHIC was also used in a nuclear
industry project for post-event analyses
of the Fukushima Daiichi Nuclear Plant
accident, evaluating the potential for
thermal stratification of a BWR pressure
suppression pool during extend RCIC
operation, hydrogen mixing in the RPV
and the reactor building, and flooding
of the plant buildings from the tsunami.
By providing additional technical
details, these analyses evaluated nuclear
operating plant response to the event.
PROTO-FLO has been used to
analyze the hydraulic performance
of supplemental cooling paths and
equipment.
RADTRAD-NAI,
in
conjunction with shielding codes, has
been utilized to support the determination
of dose to new equipment and personnel
mission dose.
3.
What enhancements have been made
to Zachry’s engineering services, field
services and its software suites to help
utilities meet the post Fukushima beyond-
design-basis event requirements?
Harrell:
Interestingly, very few en-
hancements to GOTHIC were required
to analyze some very interesting Fuku-
shima phenomena. Many people think
of GOTHIC as a containment code since
that was the original and most common
application, but GOTHIC is actually a
toolbox of thermal hydraulic capabil-
ity that can be used to analyze a wide
range of events. One of the more inter-
esting Fukushima related applications for
GOTHIC was analysis of the seismically-
induced hydraulic loads in the spent fuel
pool due to wave action. GOTHIC was
used to analyze the wave action and ensu-
ing load forces to qualify a hardened level
instrument system. Another application
was the use of GOTHIC to analyze heat-
up profiles of control rooms, auxiliary
buildings, switchgear rooms, etc. result-
ing from extended loss of power; Beyond
Design Basis events.
Proto-FLO was used to analyze the
hydraulic adequacy of supplemental
cooling paths and equipment as part of
the FLEX strategy. No modifications
were required since this application is
fundamental to the purpose of the code.
4.
What is the scope of Zachry’s
involvement in plant digital upgrade,
including
Instrument
&
Control
modernization at US nuclear power
plants?
Brinkman:
Zachry has provided
innovative and cost effective solutions
for integrating digital Instrumentation
and Controls (I&C) into the US nuclear
operating fleet. This has been successfully
accomplished at various levels: from
the single microprocessor component
replacement to the large scale, multi-
platform digital upgrade. In addition
to ensuring that the critical attributes
and design functions of a system are
adequately met by the digital technology,
the nuclear arena requires assurance that
the licensing and design basis for the
plant, upon which the license to operate
a nuclear power plant was issued, has
not been adversely impacted by the
introduction of this “new” equipment.
Zachry has intimate familiarity with the
regulatory challenges that accompany
projects of this type and our acquired
knowledge and experience has laid the
