Problems of Decommissioning Fast Reactors and Ways of their Solution on the Basis of the BR-10 Research Reactor
6/20/2022 2022 - #02 Decommissioning
At the IPPE JSC, the BR-10 research reactor was completely shut down in December 2002 after 43 years of operation. Over the years of operation, BR-10 accumulated approximately 18 – 19 m3 of alkali metals (Na of the primary and secondary circuits, Na-K alloy with mercury as an impurity), which were used as a liquid metal coolant in the primary and secondary reactor circuits and in some equipment. These wastes of alkali metals were formed as a result of three replacements of coolants in the reactor.
To process Na and Na-K alloy, the method of solid-phase oxidation (SPO) with dump slag from copper smelting production sites was chosen at BR-10. In the process of developing the technology, the complete processing of Na and Na-K alloy into a solid mineral-like product and the hydrogen safety of the SPO process were experimentally proved. Based on the results obtained, the MAGMA-SPO module with a processing capacity of 50 liters of radioactive Na per load was developed, manufactured and put into operation. The entire volume of radioactive secondary sodium (about 5.4 m3) has been processed at the MAGMA-SPO module, processing of radioactive primary sodium has begun.
To solve the problem of neutralizing Na nondrainable residues in some equipment of the reactor, the use of gas mixtures was investigated; they are based on nitrous oxide N2O, which does not generate explosive hydrogen in the course of interaction with sodium. On the basis of the scientific results obtained, the LUIZA-RW module was developed, manufactured and put into operation for the neutralization of nondrainable residues of radioactive sodium in the spent cold traps of the primary and secondary circuits and in the drain tanks of the secondary and primary circuits. At the LUIZA-RW module, two spent cold traps of the secondary circuit, nine cold traps of the primary circuit and two tanks were neutralized.
To solve the problem of purifying the NaKHg alloy from mercury, a method was found in the field of liquid metal chromatography – metallic magnesium was used as a sorbent selective to mercury when the NaKHg ternary alloy was pumped through it. Research and bench tests of the method gave a very promising practical result: with a single filtration of the NaKHg alloy through a magnesium sorbent, the degree of purification of the alloy from mercury reached 96 – 98%. Based on the results obtained, the GETTER module was developed, manufactured and installed at the BR-10 research reactor. In further studies, it was shown that a magnesium sorbent saturated with mercury can be safely disposed by separating mercury from it in the form of an insoluble solid precipitate consisting of cinnabar HgS (a natural mineral).
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spent alkaline liquid metal coolant BR-10 RR technologies for processing of alkaline liquid metal coolant solid-phase oxidation MAGMA-SPO module gas-phase neutralization LUIZA-RW module liquid metal chromatography magnesium sorbent GETTER module
Link for citing the article: Smykov V.B. Problems of Decommissioning Fast Reactors and Ways of their Solution on the Basis of the BR-10 Research Reactor. Izvestiya vuzov. Yadernaya Energetika. 2022, no. 2, pp. 90-102; DOI: https://doi.org/10.26583/npe.2022.2.09 (in Russian).