here - Atomic Energy Regulatory Board

out and clearances were issued in sub-stages, accordingly.
After satisfactory resolution of all issues arising from the
review and after completion of the prerequisites,
authorization for FAC was granted on February 25, 2007
and the unit achieved first criticality at 10:10 hours on
February 26, 2007. Subsequently, after review of the results
of first criticality, AERB granted authorization for phase-B
low power physics tests. AERB granted authorization on
March 26, 2007 for synchronization of the unit to the power
grid and operation of the reactor power up to 50 % FP
after successful completion of phase-B tests and review of
the results.
ACPSR-PHWR Members visiting KGS-3 Control Room
From L to R: Shri R.I. Gujarathi, Director, NPSD, Dr. S. M. Lee,
Chairman, PDSC-KGS-3&4, Shri S.K. Chande, VC-AERB,
Shri S.S. Bajaj, Senior ED (Safety),NPCIl and Shri K. Ramamurthy,
Station Director, KGS-3&4 Shri S.K. Chande, VC-AERB,
Shri S.S. Bajaj, Senior ED (Safety), NPCIl and Shri K. Ramamurthy,
Station Director, KGS-3&4
For KGS-4, civil construction activities and erection
of various systems, equipments and components are in
progress.
Civil construction activities and erection of various
systems, components and equipment remained in progress
for RAPP-5&6 units. It is expected that containment proof
test, Integrated Leakage Rate Test (ILRT) and PHT system
hot conditioning and light water commissioning would be
taken up for RAPP-5 in the second quarter of 2007 after
completion of required review.
Some of the important observations made during
design safety review of these 4 units and commissioning of
KGS-3 are given below.
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Containment proof test and ILRT of KGS-3 was carried
out during November 2006. Observed leakage rate
was 0.24 % of contained air volume per hour at 1.06
kg/cm 2 . Interception by Secondary Containment (SC)
was measured and was found to be more than 90 %
as per the design intent. Containment isolation test was
carried out in an integrated manner prior to FAC and
results were satisfactory.
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The hot conditioning of KGS-3 was completed
successfully and protective uniform magnetite layer of
0.43 microns was achieved. Emergency Core Cooling
System (ECCS) test and other light water tests related
to PHT system were carried out and system performance
was satisfactory.
The design feature of on-line clutch release test for
primary shutdown system has been incorporated in all
the 4 units.
Each of the 4 units has been provided with 3 Diesel
Generator (DG) sets of 2400 kW each. After site
installation, while testing of DGs of KGS-3 for the largest
available load of 400 kW of Primary Pressurizing Pump
(PPP) motor, the 6.6 KV DG terminal voltage collapsed
and the PPP motor could not be started. This was due
to voltage dip in excitation transformer, which is
supplying excitation requirements of the pilot exciter of
the alternator of DG set. The DG set performance
became satisfactory when excitation requirement of DG
alternator was fed from Class II buses. NPCIL
proposed, as an interim measure, to install a 1 kVA
inverter powered from 220 V class I buses of station
power supply to cater the excitation requirements of
the pilot exciter of each DG alternator and the proposal
was accepted after the review. NPCIL has been asked
to explore an alternate solution in consultation with
manufacturer. In view of the above, a new clause – ‘If
any of the two power UPS on its battery bank is not
available or any of the class-II buses are not available,
the reactor shall be brought to cold shut-down state’
has been added in the technical specifications for
operation.
Each of these DG sets was equipped with a Class II
electrically driven Crank Case Exhaust (CCE) fan. As
per the manufacturer, the DG sets can run safely for
~32 seconds only without availability of the CCE fan.
Logic has been provided to trip the DG sets with 27
seconds delay in case the CCE fan does not start.
Subsequently, the fan power supply was changed over
to Class III power supply to reduce the dependence of
DG starting on Class II power supplies.
For 1 of the 6 ion-chamber housings, the distance
between calandria and the housing was found to be 28
mm instead of the specified value of 20 mm. The
reason of the deviation was reviewed and the deviation
on neutron power readings/attenuation factor for the
ion-chambers was found acceptable.
Due emphasis was given for environmental
qualifications of safety related structures, equipment
and components since the design stage of KGS-3&4.
NPCIL has been asked to submit a comprehensive
report covering methodology followed, standards used,
tests done, analysis carried out, etc., in this regard for
review.
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