IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
Fig.1 Industrial version of
PCSL system
displaying BCR related outputs.
The functional test was
completed successfully.
The PCSL system is to be used
in PFBR. It will be under
industrial environment. Before
putting the system under
industrial environment, the
entire qualification test has to
be done. Finally an industrial
version PCSL system was
designed. Here all the aspects
of industrial environment have
been taken care from EMI/EMC
to environmental qualification.
In the design stage we have
implemented all the required
features. For EMI/EMC
qualification of sub rack, all the
PCBs have qualified for signal
integrity, cross talk and EMI
using Hyperlinx software and
for thermal qualification;
thermal analysis was done
using Beta-soft software. The
19" Sub rack which houses all
the PCBs is also designed to
qualify the above. Industrial
version PCSL system (Fig.1) was
implemented in a 19" rack of
48U height. General
arrangement of the system has
been made to qualify the whole
system for EMI/EMC and
environmental qualification.
V.C.3. Reliability Analysis of Safety Critical I & C
Systems of PFBR
PFBR contains many Safety
Critical Systems like, Safety
Logic Systems (Safety Logic with
Fine Impulse Test for Shutdown
system 1, Pulse Coded Safety
Logic System for Shutdown
system 2), Core Temperature
Monitoring System, etc. Atomic
Energy Regulatory Board
specifies target for the Safety
Critical System. The probability
of failure on demand of the
system should be less than the
target. During the design of a
safety critical system, reliability
target of the system will be
considered among other
requirements.
The Instrumentations &
Control systems important for
safety can be broadly classified
into two categories, viz. i)
Safety-Critical systems and ii)
Safety-Related systems. The
Safety Critical systems form the
second layer of defense and
are provided to assure safe
shutdown of the reactor,
removal of heat from the
reactor core during any
deviation from normal
operation and containment of
radioactivity during accident
conditions. The Safety Critical
systems, for example, Core
Temperature Monitoring
system, require a very high
reliability.
Various reliability analysis
techniques like Failure Modes
and Effects Analysis (FMEA),
Fault Tree analysis (FTA), Event
Tree Analysis are performed as
a part of Probabilistic Risk
Assessment. Relex Software,
shown in Fig.1, is popularly
used to perform these analyses.
FMEA is a bottom up approach
where the failures of each
component of the system are
identified along with their
modes of failures. Effects of
those failure modes on the
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