# Carrying out Calculations of Radiation Safety During Unloading and Disassembly of Cores of Spent Removable Parts of Reactors with Liquid Metal Coolant of Submarines

6/20/2022 2022 - #02 Global safety, reliability and diagnostics of nuclear power installations

Devkina E.V. Suslov I.R. Chernov V.A.

https://doi.org/10.26583/npe.2022.2.07

### UDC: 621.039.7+519.245

The results of calculations of radiation safety when treatment the spent removable part of reactors of nuclear submarines with a liquid metal coolant are presented in the article. The spent removable part of reactors of nuclear submarines with a liquid metal coolant are sources of intense neutron and gamma radiation. The shield should greatly reduce neutrons and gamma so that total dose rate from neutrons and gamma quanta should not exceed 2 mSv/h on the surface of the container and 0.1 mSv/h at a distance of 2 meter from the surface of the container.

A homogeneous core model was used for calculations. Sources from neutrons in spent fuel, sources of gamma from fission fuel products, from europium in control rods, from the reactor vessel and fuel grids were considered. The dose rates of neutrons and photons were calculated using the MCNP program.

Direct calculations of dose rate of neutrons and secondary gamma are generally reliable. Direct calculations of problems with a source of gamma quanta had large variance values. These problems were calculated with variance reduction methods: geometry splitting with Russian roulette and the MAGIC (Method of Automatic Generation of Importances by Calculation) method.

Values of dose rates were obtained with an acceptable error. The results of the calculations helped in the treatment of spent nuclear fuel. The results of the calculations were used in the design and making of the shield.

### References

- Zabud’ko A.N., Ignat’ev S.V., Somov I.E., Pankratov D.V., Suvorov G.P., Vygodin V.T., Nikolaev S.A., Tihomirov V.I. Problems of handling spent nuclear fuel from liquid metal reactors of nuclear submarines Proc. of the IIIth Intersectoral Scientific and Practical Conference «Heavy liquid)metal cooland in nuclear technologies» Ed. Prof. G.I. Toshinskij. Obninsk. GNTs RF – FEI Publ., 2008, v. 2, pp. 547-553 (in Russian).
- Zrodnikov A.V., Zabud’ko A.N., Ignat’ev S.V., Nikolaev S.A., Pankratov D.V., Somov I.E., Suvorov G.P., Toshinskij G.I., Dragunov Yu.G., Vahrushin M.P., Stepanov V.S., Trantin S.K., Vasilenko V.A., Zhuravlyov V.P., Filatov B.V., Filin R.D. Problems and Approaches to Handling Spent Nuclear Fuel from Liquid Metal Reactors of Nuclear Submarines. Izvestiya vuzov. Yadernaya Energetika. 2007, no. 1, pp. 13-22. Available at: https://static.nuclear-power-engineering.ru/journals/2007/01.pdf (accessed Oct. 01, 2021). (in Russian).
- Zrodnikov A.V., Ignat’ev S.V., Pankratov D.V., Toshinskij G.I., Zabud’ko A.N., Sazonov V.K. Unloading, storage and subsequent handling of spent nuclear fuel of reactors with liquid metal coolant: status and problems. Proc. f the Intern. Sci. Seminar Russia)NATO. «Scientific and Technical Problems Ensuring Safety Handling of Spent Nuclear Fuel and Radioactive Waste from Dismantled Submarines and Ships with Nuclear Power Plants». Ed. Acad. A.A. Sarkisov. Moscow. IBRAE, 2004, p. 33 (in Russian).
- The Program Complex MCNP4B with Data Library DLC189/MCNPDAT. The Certification Passport of the Software No. 236 dated Sept. 18, 2007. Moscow. NTTs YaRB Publ., 2009 (in Russian).
- Gusev N.G., Klimanov V.A., Mashkovich V.P., Suvorov A.P. Shielding of Ionizing Radiation: Vol. 1. Physical Basis Shielding of Ionizing Radiation. Moscow. Energoatomizdat Publ., 1989, 512 p. ISBN 5-283-02971-9 (in Russian).
- Devkina E.V. Features of Monte Carlo Calculations for a Two) Dimensional Benchmark for Shielding of Transport and Packaging Containers for Spent Nuclear Fuel. GNTs RF – FEI Preprint-3283. Obninsk. IPPE JSC Publ., 2018, 20 p. (in Russian).
- Chernov S.V., Son’ko A.V., Horomskij V.A. Calculation of Radiation Fields by Iteration Method of Weight Window in the Project АSММ 10/100 кilowatt. Proc. of the X)th Jubilee Russian Conference «Radiation Shielding and Radiation Safety in Nuclear Technologies». Moscow-Obninsk. NOU DPO TcIPK Rosatoma Publ., 2015, pp. 9-10 (in Russian).
- NP-053-04. Safety Rules for the Transport of Radioactive Materials. Moscow. Federal’naya Sluzhba po Ekologicheskomu, Tekhnologicheskomu i Atomnomu Nadzoru Publ., 2004, 135 p. (in Russian).
- Trykov L.A., Kolevatov Yu.I., Volkov V.S. Methods for Calibrating Spectrometers Using Radionuclide Neutron Sources. GNTs RF – FEI Preprint-1730. Obninsk. IPPE JSC Publ., 1985, 76 p. (in Russian).

spent removable part of reactor dose rate geometry splitting with Russian roulette MAGIC (Method of Automatic Generation of Importances by Calculation) method

**Link for citing the article:**
`Devkina E.V., Suslov I.R., Chernov V.A. Carrying out Calculations of Radiation Safety During Unloading and Disassembly of Cores of Spent Removable Parts of Reactors with Liquid Metal Coolant of Submarines. Izvestiya
vuzov. Yadernaya Energetika. 2022, no. 2, pp. 73-80; DOI: https://doi.org/10.26583/npe.2022.2.07 (in Russian).`