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NuclearPlantJournal.com Nuclear Plant Journal, January-February 2016
Research &
Development
Hungary Joins EPRI
The supplier of half of Hungary’s
power consumption has joined EPRI’s
nuclear research program. In 2013, Paks
Nuclear Power Plant’s four units produced
51%of the country’s electricity, according
to the Nuclear Energy Agency. Leaders
and staff at the 2,000-megawatt facility
now will have access to a global R&D
collaboration and key EPRI guidance to
support safe, reliable operations.
Paks’ collaboration with EPRI will
provide nuclear plant operators around
the world with new opportunities to draw
on plant technical knowledge spanning
more than three decades of operation.
The Russian-designedVVER 440 nuclear
reactors at Paks are also deployed in other
eastern and central European countries.
The Paks collaboration will allow EPRI
to broaden the reach of its technical
guidance to this technology.
Other VVER operators participating
in EPRI nuclear programs include CEZ
(Czech Republic), Slovenské elektrárne
(Slovakia), and CNNC (China)—
operating 16 VVER units with an
aggregate capacity of 10 gigawatts. With
Paks, CEZ, and other VVER plants, EPRI
is expanding its opportunity to capture
the state of industry knowledge and R&D
on degradation mechanisms in VVER
plants.
Radiation Dose
Reduction
In demonstrations at two nuclear
plants in Korea, a first-of-its-kind system
that remotely monitors radiation, reduced
worker radiation dose by 37%. Korea
Hydro & Nuclear Power (KHNP) has
been developing the system since 2010,
assisted by EPRI researchers and its
radiation monitoring guidelines.
Traditionally, nuclear plant workers
wear personal dosimeters that monitor
radiation and require separate devices
to transmit data to radiation protection
personnel. KHNP’s system integrates
lighter personal monitoring devices
with wireless communications, enabling
radiation protection personnel to track
radiation levels in real time. Through
continuous video, the protectionpersonnel
view plant maintenance workers, using
the integrated audio communications to
advise workers of abnormal conditions
and provide safety instructions in real
time.
Building
on
the
successful
demonstrations, KHNP plans to deploy
the technology throughout its 23-unit
nuclear fleet. The utility estimates that
developing the system in-house will save
more than $10 million.
EPRI is looking to use data collected
from these tools, along with its 3-D
Radiation Field Estimation Algorithm
and a source term analysis tool, to more
accurately predict outage dose rates and
to estimate worker dose in areas where
direct measurement is not available.
Nuclear utilities can use these estimates
to enhance their radiation protection
programs. Potentially, the data can be
combined with augmented reality tools to
help workers visualize radiation fields as
their work takes them to various parts of
a plant.
Nozzle Inspection
By Chris Warren
To ensure that pressurized water
reactors in certain nuclear power plants
are functioning properly, it’s necessary
to insert an ultrasonic inspection device
through three-quarter-inch nozzles on
the reactor vessel’s bottom head (known
as bottom-mounted instrumentation
nozzles).
There’s little room for error. The
technician must remotely guide a robotic
arm from the top of the reactor to the
bottom of a 110-foot-deep cooling water
pool surrounding the reactor. Video
transmitted from the delivery tool inside
the reactor helps guide the technician
through the task. “It takes the skilled
hand of an operator to get the probes
where they need to go,” said EPRI
Principal Project Manager Robert Grizzi.
“It’s like threading a very tiny needle.”
Nuclear plant operators conduct this
comprehensive nozzle inspection when
initial visual exams reveal potential areas
of concern.
Mock-up Requirement
This job cannot be done by just
anyone. It is standard practice for nuclear
utilities to hire specialized vendors to
complete the inspection procedures,
which are governed by federal regulations
and American Society of Mechanical
Engineers (ASME) codes and standards.
In 2013, Arizona Public Service
(APS) asked EPRI to help ensure that
the vendor it selected for comprehensive
nozzle inspections at its Palo Verde
Unit 3 nuclear plant could do the
work properly. “The vendor needed to
demonstrate that its inspection technique
works and follows standards and federal
requirements,” said Grizzi.
To assess the vendor’s effectiveness,
EPRI built a full-scale replica of a
bottom-mounted instrumentation nozzle
at Palo Verde Unit 3, incorporating
cracks and other defects in it. The
vendor successfully inspected the mock-
up in accordance with standards and
regulations, locating all the cracks.
By qualifying the vendor, the
demonstration enabled APS to decide
to move forward with its inspection. It
also helped the utility prepare for future
inspections, avoiding extended outages.
“If APS didn’t have the vendor,
equipment, and processes ready for the
comprehensive inspection, it could have
taken five to six months to find and qualify
the vendor,” said Grizzi. “The plant can’t
go online until all that is in place.”
Application to Other Plants
Given Palo Verde’s unique reactor
designs, the results of the EPRI-APS
collaboration are not directly transferable
to other nuclear plant operators.
Nevertheless, the mock-up methods
and experience equip EPRI to construct
and test customized mock-ups for other
plants. “There will eventually be follow-
up work,” said Grizzi. “When we have the
opportunity to apply the same methods, it
can enable as positive an impact for other
utilities as it did for APS.”
