Nuclear Plant Journal, May-June 2014 NuclearPlantJournal.com
39
Development of
Integrated NIMS (I-NIMS)
A new version of the NIMS,
called I-NIMS (Integrated NIMS) was
developed to enhance and substitute the
conventional NIMS in 2008 and has been
continuously upgraded by Korea Atomic
Energy Research Institute (KAERI). The
I-NIMS is capable of performing on-
line condition monitoring and integrated
structural health diagnosis of the pressure
boundary components in NSSS.
The major distinctive feature of
the I-NIMS is to make full use of the
whole signals obtained from the different
subsystems’ field sensors, incorporating
the high speed multi-channel signal
processing hardware and the data fusion
technology. The unfiltered raw signals
directly sampled from field sensors such
as accelerometers, AE sensors, proximity
probes, and ex-core neutron detectors
have a common feature in that they can
be multi-dimensionally correlated by
the phenomena due to the vibration or
wave propagation of the reactor pressure
boundary components. For example,
the impact signal generated by a loose
part can be detected not only by the
accelerometers of LPMS, but also by the
AE sensors of ALMS. Since the sensor
locations of the LPMS are different from
those of the ALMS, the ALMS sensors
can be utilized as virtual sensors for loose
part monitoring and diagnosis.
The second outstanding feature of the
I-NIMS is that it has employed advanced
digital signal processing techniques that
can remarkably improve the monitoring
and diagnostic capabilities. For example,
the new LPMS is equipped with a two
dimensional time-frequency analysis
(smoothed Wigner-Ville distribution)
technique that makes it possible to
more accurately estimate the TOADs
(Time-Of-Arrival Differences) between
different flexural wave groups than ever.
In addition, the I-NIMS is including
state-of-the-art technical tools such as
three dimensional computed tomography
algorithm for source localization, a new
mass estimation algorithm, the mode
separation algorithm for the reactor
internal vibration, principal order
analysis, and directional spectra, etc.
In order to confirm the capability
of the developed I-NIMS, a SAT (Site
Acceptance Test) was performed at
Henbit nuclear power plant unit 3. The
functional capabilities of the hardware
and software have been fully tested,
verified, and the related new techniques
have been registered for patents.
Therefore, it is expected that the I-NIMS
can exclusively improve the monitoring
and diagnostic reliability compared to the
conventional NSSS integrity monitoring
system.
Summary
The Integrated NIMS (I-NIMS)
has been developed and being upgraded
by KAERI. The various functional
capabilities of the I-NIMS hardware and
software have been tested and verified
through a site acceptance test performed
in Hanbit nuclear power plant unit
3. It is expected that the I-NIMS can
enhance the monitoring and diagnostic
reliability compared to the conventional
NSSS integrity monitoring system. The
I-NIMS can be commercially supplied
in any form of customization such as
an integrated system, selection of a
subsystem, application software only, or
database management software only.
Contact:
Jin-Ho Park, Korea Atomic
Energy Research Institute, 989-111
Daedeok-daero, Yuseong-gu, Daejeon,
305-353, Korea; telephone: 82-42-868-
Schematic of the Integrated NIMS.
