Nuclear Plant Journal, January-February 2016 NuclearPlantJournal.com
23
ICDAs are a standard feature on
pressurized water reactors designed by
Combustion Engineering (predominantly
in the United States and Korea) and
Babcock & Wilcox. In addition, one or
two Westinghouse plants use ICDAs. The
KONVOI units in Europe use both fixed
ICDAs and a moveable system called
aeroball measurement system.
7.
Describe the procedure to replace
old detectors with ICDAs in an operating
plant?
Self-powered neutron detectors
based on rhodium or cobalt deplete
or “burn-out over time. Therefore, the
ICDAs are periodically replaced.
Replacing one or more ICDAs
requires drain down of the in-core tank
since it is initially flooded during the
outage. After approximately six hours,
the ICDAs are disconnected and pulled
to the park position for the outage. This
removes the assemblies from the core to
allow fuel shuffle.
Then the in-core tank is re-flooded
so the ICDAs scheduled for replacement
can be pulled and cut into pieces under
water. This minimizes radiation dose to
the workers. The pieces are then placed in
a canister for storage on site. The tank is
drained and the new ICDAs are installed.
8.
How has the vulnerability to cyber
threats and electromagnetic interference
been addressed in ICDA systems?
ICDA signals are amplified,
conditioned and sent to the plant computer
via hard-wired connections. Data access
ports are often available to engineers or
computer software specialists that need
to review the data or use it for core flux
mapping. The approach to cyber security
and eliminating threats is specific and
confidential to each site. Vulnerabilities
related to electromagnetic interference are
addressed by testing the signal processing
equipment to industry standards such as
MIL-STD-461E,
Requirements for the
Control of Electromagnetic Interference
Characteristics of Subsystems and
Equipment
.
Contact: Curtis Roberts, AREVA,
Inc., telephone: (202) 974-8766, email:
In-core Detector Assembly.
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