Page 118 - AERB

7.6.9 Experimental Studies of Iodine Behaviour in
Reactor Containment

In order to minimize the release of radioactivity
to environment in the low probable postulated LOCA
initiated severe accident conditions, it is essential
to study the fission products behaviour. Iodine is a
major contributor to the potential source term to the
environment. Understanding its behaviour inside the
containment and also in the environment is an essential
prerequisite for arriving safety margins.

To study the iodine behaviour in containment, lab
scale experimental setup was designed at chemistry
laboratory at SRI Kalpakkam. By this experimental setup
iodine interaction with paint and iodine adsorption Fig. 7.21: pH Influence on Nitrate removal from Aqueous
properties on various adsorbents is being studied. The Streams
experimental set up was installed and experimental
parameters were optimized. Iodine vapours are 7.7 REACTOR PHYSICS STUDIES
generated using re-sublimized iodine and vapours were
passed through the reaction chamber by using argon as 7.7.1 Safety Review and Analysis of First Approach
a carrier gas and scrubbed through potassium hydroxide to Criticality of KAPP-3&4
solution.
The KAPP-3&4 PHWR-700 MWe design utilizes
7.6.10 Experimental Studies Pertaining to removal various safety systems and features to meet the requisite
of Nitrate from Aqueous Stream safety requirements as brought out in AERB regulatory
documents. Calculations were carried out to study
Waste water streams containing nitrate are being First Approach to Criticality (FAC) of KAPP-3 using
generated at various stages in nuclear fuel cycle independent core neutronics code system. The results
operations. These aqueous streams are neutralized like variation of effective neutron multiplication factor
prior to either storage or biological treatment. Among and reactivity due to draining of ZCCs, withdrawal of
the different treatment techniques, denitrification of various reactivity devices and boron dilution during
waste stream using nano catalysts such as zero valent FAC were calculated and compared with the design
iron is a promising alternative technique. In-house calculations as part of independent verification.
synthesis, characterization and evaluation of zero-valent
iron nanoparticles have been carried out. Nano sized 7.7.2 Safety Analysis of TAPS BWR Core using In-
zero-valent iron particles (nZVI) were synthesized by house Code
chemical reduction method. Influence of experimental
conditions on nitrate removal including pH, catalyst As a part of independent verification of safety
loading, effluent concentration, reaction time etc. was analysis, reactor physics studies have been initiated
systematically studied (Fig. 7.21). Using the catalyst, using in-house computer code VISWAM. Independent
the nitrate present in the liquid waste is converted to lattice physics calculations are carried out for the
innocuous products which can be easily disposed into reload pattern 2 fuel. The lattice burn-up code has
the environment. More than 90 % nitrate removal been used and salient results like the variation of the
could be achieved in 60 min using the synthesized neutron multiplication factors (K and K ) with burn-
∞
eff
nanoparticles. up, different fuel temperature are calculated for the
lattice. Further, various reactivity effects due to change

90 AERB Annual Report 2019