here - Atomic Energy Regulatory Board

! The experts committee, which reviewed the seismic
qualification report, noted that the stresses as brought
out in the analysis for seismic response of Calandria -
End Shield integral assembly of KGS-1&2 (also
applicable for KGS-3&4/RAPP-5&6) are found to meet
the stipulated requirements of ASME Section-III,
subsection-NB.
! NPCIL has agreed, as per AERB stipulation, for
upgradation of Equipment Decontamination Facility to
handle equipment with surface dose rate upto 50 mSv/
h, as against 10 mSv/h envisaged in the earlier design.
! It was noted, during regulatory inspections, that
dimensional mismatch between foundation and
equipment base-plate has occurred for few equipment
(e.g., Active Process Water Cooling System pumps and
pedestal of HP Heater 6 at KGS-3 and PHT Storage
Tank, Vapour Suppression Pool Re-circulation Pump
and End-shield Cooling Pumps of RAPP-5). The site
has been asked to prepare a complete list of such
equipment for measurement of vibrations of piping and
equipment during commissioning phase. Designers were
asked to re-look into the stress analysis carried out earlier,
in view of changes in the support design.
! NPCIL was asked to ensure proper maintenance of
water chemistry in the vapour suppression pool to
minimise the corrosion effect on the down-comers in
the system. This is based on the operational experience
from NAPS/KAPS.
! Geometric imperfections were noticed on the outer
surface profile of inner containment dome of KGS-3.
Based on the review by AERB, corrective measures were
incorporated for the subsequent dome construction.
Safety of as-built dome was found satisfactory under
all applicable design load combinations.
KK- NPP-1&2
For KK-NPP consisting of two Russian design VVER
reactors, each of 1000 MWe capacity, Co-ordination Group
(KK-CG) along with the Specialist Groups (SGs) carries out
the first level of review. The ACPSR-LWR, at the second
level, reviews the recommendations of KK-CG/SGs along
with the relevant documents. The review process is currently
focused on the next stage of regulatory consent, i.e.,
Clearance for Erection of Major Equipment (EE).
The 88 th Board meeting was held at KK-NPP site.
The members were apprised of the status of the construction
of the Units. The members visited the power project and
12
witnessed the construction work in progress. A visit was also
made to the IREL plant at Manavalakurichi.
AERB Board Members with Site Officials at KK-NPP Site
The review of specific topics like Reactor Pressure
Vessel Design and related aspects, Water Chemistry and
Materials has been completed. Specialist Group on PSA
has been reviewing the PSA Level - 1 Report. Most of the
issues that were brought out during the review of PSAR
(Rev.1) have been satisfactorily addressed in PSAR (Rev.-
2). Actions have been initiated towards resolution of the
balance issues, as relevant to EE.
Some of the salient observations/recommendations
are the following.
! The design requirements as given in PSAR packages on
seismic and environmental qualification of safety related
equipments and components have been reviewed.
! The Validation and Verification (V&V) document for
thermal hydraulic codes for accident analysis was
reviewed and found acceptable. The methodology for
review of V&V of Computer Based systems is under
formulation.
! Unbonded cables are being used for the first time for
internal pre-stressing of the containment. A mock up
using modified scheme for threading of cables in the
horizontal duct has been conducted satisfactorily.
! The plant is provided with a special cooling system,
which caters to the heat load of spent fuel pond and
core residual heat removal following reactor shut down.
The consequences of sharing a normal process function
and safety performance under different off-normal
conditions were reviewed. This design practice followed
in Russian plants was accepted subject to certain
stipulations.