Nuclear Plant Journal, March-April 2015 NuclearPlantJournal.com
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Akbar Moarefy
Akbar Moarefy is the Senior Consulting
Engineer at Diablo Canyon Power
Plant. He has functioned as lead design
engineers in diverse projects such as
design of failed fuel
monitoring system,
setpoint control
program, generator
output breaker,
and Environmental
Qualification,
Wireless project.
Moarefy has about 18
years of experience in
commercial nuclear
industry and 9 years
of experience as a
reliability manager
in semiconductor
industry.
He has a BSEE from University of
Illinois in Chicago.
The following laboratory experiments are
now being carried out:
1. Representative I&C equipment
installed in AMS’s anechoic
chamber is being radiated with
representative wireless signals (e.g.,
Wi-Fi, Bluetooth, cellular including
4G and LTE) both discretely and in
combination to evaluate the impact
of multiple wireless protocols.
2. During testing, wireless signal
parameters such as modulation,
duty cycle, and field strength are
being varied to identify unacceptable
performance
in
monitored
equipment.
3. Test configuration characteristics
outlined in MIL-STD and IEC
susceptibility standards (e.g. field
strength, antenna distance and
orientation, near field vs. far field
effects, dwell times) are being varied
to determine whether they negatively
affect I&C equipment performance.
As an example of these experiments
to characterize wireless devices’
immunity, AMS is now using a gigahertz
transverse electromagnetic (GTEM) wave
cell to broadcast signals onto equipment
under test within the chamber. Used for
radiated immunity testing according to
the IEC 61000-4-20,
Electromagnetic
Compatibility
, test standard, the GTEM
cell creates a uniform electric field and
exposes it to the equipment under test.
For the investigation testing of nuclear-
grade equipment, a frequency range of
170 MHz to 6 GHz has been used to cover
the frequencies used by various wireless
devices under separate tests performed
at field strengths of 5, 10, 20, and 50
V/m (note that although a cell phone can
generate nearly 100 volts per meter the
electric field strength falls to about 4 V/m
6 feet away from the
phone). Amplitude
modulation
per
the IEC 61000-4-
20:2003
standard
was used in order
to encompass the
modulation schemes
of a wide range of
wireless devices.
Once the immu-
nity test methods are
identified that best
highlight the effects
of wireless devices,
generate reproducible
results, and provide
sufficient efficiency and conservatism,
those methods will be incorporated into
the final integrated testing system.
For the second module--a cognitive
radio system to test the coexistence ca-
pabilities of wireless devices--AMS has
begun developing test methods to assess
wireless coexistence. Currently, coex-
istence has been investigated through
computer simulation studies, coexistence
working groups exist such as the IEEE
802.19,
Wireless Coexistence Technical
Advisory Group
, technical Advisory
Group (TAG), and ANSI’s initial work
on a coexistence methods for the medi-
cal industry. However, there is currently
no comprehensive test method to assess
wireless coexistence in the laboratory or
in situ in an industrial environment. To
fill this gap, AMS is using its GTEM cell,
to subject a representative wireless device
such as a router or tablet to an electro-
magnetic (EM) environment that repli-
cates both fixed and mobile wireless de-
vices. This testing environment will con-
sist of both signal generators that produce
conventional modulation techniques (e.g.
amplitude, frequency, and phase modu-
lation) and more complex modulation
schemes found in Wi-Fi and Bluetooth
transmitters as well as a National Instru-
ments RF generator that can produce sig-
nals from multiple wireless protocols.
By varying wireless signal attributes
such as channel assignment, signal
strength, and network traffic AMS is
now evaluating the impact on the I&C
equipment. The effects of multipath
will also be considered for the signal
generation. To monitor the performance
of the tested equipment, we have
established a wireless communication
link to monitor performance parameters
such as latency, bit error rate (BER),
packet error rate (PER), and overall
data integrity. Moreover, by varying
the attributes of EM environment we
are determining preliminary coexistence
acceptance criteria by evaluating the
Figure 1.
