Methods of Removing Corrosion Product Deposits from the Primary Circuit of Light-Water Reactors under Transient Operating Conditions (Review)

• Published in: Thermal engineering 2021, Vol.68 (5), p.361-369
• Main Authors: Orlov, S. N., Zmitrodan, A. A., Krivobokov, V. V.
• Format: Article
• Language: English
• Subjects: Ammonia; Coolants; Corrosion; Corrosion products; Deposits; Disintegration; Engineering; Engineering Thermodynamics; Heat and Mass Transfer; Hydrazines; Light water reactors; Marine propulsion; Nuclear fuels; Nuclear propulsion; Nuclear reactors; Primary circuits; Purification; Reagents; Water chemistry; Water Treatment and Water Chemistry; Zinc
• ISSN: 0040-6015; 1555-6301
• DOI: 10.1134/S0040601521040042

In this paper, methods for removing corrosion product deposits from the primary circuit of light-water reactors with pressurized coolant under transient operating conditions are considered. The analysis of these methods, which are successfully used in the main types of light-water reactors, such as PWRs, VVERs, and nuclear marine propulsion reactors, has shown that the promising lines for their development are the selection of chemical reagents that do not violate the water chemistry of the coolant and provide the effective removal (disintegration or dissolution) of corrosion product deposits and experimental validation of their use. To disintegrate the deposits in the VVER-type reactors, hydrazine can be used; hydrazine and ammonia can be used for this purpose in marine nuclear propulsion reactors. The formation on the surface of fuel assemblies of bonaccordite (Ni 2 FeBO 5 ) as a result of coolant boiling is a serious problem that may arise during the purification of the primary circuit from corrosion product deposits under transient conditions in the PWRs. To prevent the formation of this compound, it is proposed to adjust the water chemistry of the primary coolant so that the pH value of the medium is at 7.4 throughout the entire reactor’s operational period. The mutual influence of the methods for removing corrosion product deposits under transient operating conditions of nuclear reactors and the technology of injecting zinc into the primary circuit coolant has been analyzed. It has been shown that the technological solutions proposed can complement each other and, despite widespread applications of the zinc-injection technology, the purification methods still remain topical under transient operating conditions of the reactor. The purification methods under investigation have proven their applicability to the basic light-water reactors, such as PWRs and VVERs, as well as nuclear marine propulsion reactors.