Original scientific paper
The Efficiency of Nuclear Ion Exchange Resins Applied in the Primary Circuit Demineralizers of NPP Krško
Violeta Čalić
orcid.org/0000-0002-0076-089X
; Krško Nuclear Power Plant Vrbina 12, 8270 Krško, Slovenia
Abstract
Chemistry can influence dose rates by two aspects: chemistry conditions applied in the
primary circuit and removal of (in)soluble particles. Since the primary coolant activity can have a
significant impact on area dose rates and personnel doses, the main objective of purifying the
primary coolant is to act on the radioactive source and keep it as low as reasonably achievable.
Reduction of occupational exposure maintains confidence among workers and the public. Other
factors, such as fuel duty, cycle operation, length and history, materials, steam generator (SG)
surface area and particulate redeposition, also have significant contribution to the doses.
Ion exchange (IEX) is one of the most common and effective liquid effluents treatment
methods in nuclear fuel cycle operations. IEX technology encompasses the sciences of
thermodynamics, kinetics, ion chemistry, fluid mechanics, and economics. In the industrial water
treatment, cation exchangers are used in combination with downstream anion exchangers or as a
mixed bed demineralizer (combination of both cation and anion) for full demineralization. IEX is
also an effective treatment method for liquid radioactive waste. In spite of its advanced stage of
development, various aspects of ion exchange technology are being studied to improve its
efficiency and economy in its application to radioactive waste management and coolant cleaning
processes.
Over the years desire to improve the efficiency of fine colloidal particles removal and
corrosion particulate removal in the primary systems has increased. There is a need for more and
more efficient purification in order to decrease worker’s dose during maintenance but also to
decrease volumes of radioactive resin waste. Homogenization of products and usage on primary
coolant treatment take into account the compromise between source term reductions, liquid and
solid waste, and buying and disposal cost. As the disposal costs are much greater than the buying
costs, optimization of the lifetime of the purification media, along with an increasing efficiency of
pollutant removal is a major goal.
One of the effective purification methods for particulate removal is layering of macroporous
(MP) resin in clean-up beds, spent fuel pit (SFP) and radwaste beds.
Lately, MP resins were also implemented in the primary circuit demineralizers of NPP Krško.
The paper evaluates resin purification efficiency of different primary media, and assesses
performance of gel and macroporous resin types.
Keywords
ion exchange; resin; macroporous; gel; primary water purification; demineralizer; dose rate
Hrčak ID:
199626
URI
Publication date:
15.10.2017.
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