GAMMA-SPECTROMETER FOR WATER AREAS AND BOTTOM SEDIMENTS RADIATION MONITORING

In order to solve the problem of continuous or periodic monitoring of water areas affected by radioactive contamination in the result of scheduled emissions in nuclear power plants or in the result of emergency situations in nuclear fuel cycle plants we need to develop measurement instruments with advanced mathematics and program support to assess the level of radioactive contamination with required accuracy. The aim of theoretical research was to optimize detection device construction, estimate spectrometer metrological parameters in given measurement geometries, and determine effective position of detection device in the process of in situ measurements. This device consists of spectrometric scintillation probe packed into sealed container (detection device) based on NaI(T1) crystal of Ø 63 × 63 mm or Ø 63 × 160 mm size, cable reel with deep-sea cable and a tablet PC for data processing and displaying. The container withstands static hydraulic pressure up to 5 MPa and can be used for measurements at depths of 500 m maximum. Probe measures energy distribution of gammaradiation with energy from 70 keV to 3000 keV. The implemented three-dimensional system for detection device position and orientation determination allows automatic operation of the device (without operator) for water areas or bottom sediment scanning. The spectrometer can output measurement results with threedimensional geographical coordinates as index maps of distribution with necessary resolution and accuracy. Monte Carlo models of spectrometer and controlled objects are developed in order to determine the detector response functions to given radionuclides in given measurement geometries without use of expensive standard measures of activity. Multifunction gamma-spectrometer for in situ radiation monitoring of water areas and bottom sediments was developed and constructed. In the result of theoretical researches the response functions have been calculated in the form of theoretical spectra of monitored radionuclides in definite measuring geometries. The results of mathematical modeling of the gamma-emitting transfer process allowed to estimate effective position of detection device for in situ measurements of specific activity radionuclides ¹³⁴Cs and ¹³⁷Cs in bottom sediments. 

1. Grishin D.S., Kuchin N.L., Kiziurov V.C., Laykin A.I., Miheev U.V., Triumphov N.H., Chistiakov O.B., Kharitinov I.A. [Submersible gammaspectrometers – the application experience and prospects of using]. ANRI, 2016, no. 2, pp. 10–21 (in Russian).

2. Thornton B., Ohnishi S., Ura T., Odano N., Sasaki Sh., Fujita Ts.,Watanabe T., Nakata K., Ono Ts., Ambe D. Distribution of local 137Cs anomalies on the seafloor near the Fukushima Dai-ichi Nuclear Power Plant. Marine Pollution Bulletin, 2013, no. 74, pp. 344– 350. doi: 10.1016/j.marpolbul.2013.06.031

3. Zhukouski A., Chirikalo V., Guzov V., Kozhemyakin V., Kutsen S., Khrutchinsky A., Fukuhara T., Yajima T., Mogi M., Mogi K., Chudakov V. AТ6104DM gamma-spectrometer for radiation monitoring water areas and bottom sediments. Results of mathematical and experimental researches. Problemy prikladnoj spektrometrii i radiometrii [Problems of applied spectroscopy and radiometry], St. Petersburg, 2015, pp. 160–163.

4. Appleby L.J., Dewell L., Mishara Yu.K. The ways of migration of artificial radionuclides in the Environment. In F. Warner and Harrison (eds.). Moscow, Mir Publ., 1999, pp. 512 (in Russian).

5. Kazennov A.Y, Hapanov I.A., Pimenov A.E. [Methods of operational radiation surveys of coastal waters fleet bases with the help of submersible gammaspectrometers]. Atomnaya energiya [Atomic energy], 2010, vol. 9, no. 2, pp. 100–108 (in Russian).

6. Jones D.G. Development and application of marine gamma-ray measurements: a review. Journal of Environmental Radioactivity, 2001, no. 53, pp. 313–333.

7. Vlastou R., Ntziou I.Th., Kokkoris M., Papadopoulos C.T., Tsabaris C. Monte-Carlo simulation of γ-ray spectra from natural radionuclides recorded by a NaI detector in the marine environment. Applied Radiation and Isotopes, 2006, no. 64, pp. 116–123. doi: 10.1016/j.apradiso.2005.07.011

8. Aakenes U.R., Radioactivity monitored from moored oceanographic buoys. Chemistry and Ecology, 1995, no10, pp. 61–69. doi:10.1080/02757549508035330.

9. Baranov I., Kharitonov I., Laykin A., Olshansky Yu. Devices and methods used for radiation monitoring of sea water during salvage and transportation of the Kursk nuclear submarine to dock. Accelerators, Spectrometers, Detectors and Associated Equipment, Section A, 2003, no. 505, pp. 439–443. doi: 10.1016/S0168-9002(03)01116-1

10. Wedekind C., Shilling G., Güttmüller M., Becker K. Gamma-radiation monitoring network at sea. Applied Radiation and Isotopes, 1999, no. 50, pp. 733– 741. doi: 10.1016/S0969-8043(98)00062-1

11. Povinec P.P., Osvath I., Baxter M.S. Underwater gamma-spectrometry with HPGe and NaI(Tl) detectors. Applied Radiation and Isotopes, 1996, no. 47, pp. 1127– 1133. doi: 10.1016/S0969-8043(96)00118-2

12. Birila A., Chirikala V., Zhukouski A. Spektrometr pogruzhnoj [Submersible Spectrometer]. Patent BY no. 3278, 2015.

13. Zhukouski A., Mogi K., Kutsen S. [In situ measurement of soil radioactivity]. Vestsi NAN Belarusi, Fiziko-tekhnicheskaya seriya [Proceeding of the National academy of sciences of Belarus, physico-technical series], 2016, no. 3, pp. 105–110 (in Russian).

14. Zhang Y., Li Ch., Liu D., Zhang Yi., Liu Ya. Monte-Carlo simulation of a NaI(Tl) detector for in situ radioactivity measurements in the marine environment. Applied Radiation and Isotopes, 2015, no. 98, pp. 44–48. doi: 10.1016/j.apradiso.2015.01.009

15. Kinchakov V.S. Performance optimization of a deep-sea scintillation gamma detector. Technical Physics, 2006, vol. 51, no. 1, pp. 134–138. doi: 10.1134/S106378420601021X

16. Dreyzin V.E., Sideleva N., Logvinov D. [Simulation instrumental gamma spectra of scintillation detector using a macro approach]. ANRI, 2014, no. 3, pp. 2–12 (in Russian).

17. Bagatelas C., Tsabaris C., Kokkoris M., Papadopoulos C.T., Vlastou R. Determination of marine gamma activity and study of the minimum detectable activity (MDA) in 4π geometry based on Monte-Carlo simulation. Environmental Monitoring and Assessment, 2010, no. 165, pp. 159–168. doi: 10.1007/s10661-009-0935-4

18. Briestmeister J.F. Ed. MCNPA general MonteCarlo N-particle transport code, Version 4A. Report LA12625-M, Los Alamos. NM, Los Alamos National Laboratory, 1994.

19. Zhukouski A., Kutsen S., Khrutchinsky A., Tolkachev A., Guzov V., Kojemiakin V., Chudakov V. [Evaluation of the area of influence of the contaminated soil region in solving the problems of radiation monitoring by in situ]. Pribory i metody izmerenij [Devices and Methods of Measurements], 2014, no. 1 (8), pp. 119–124 (in Russian).

20. Yekidin A.A., Zhukovski M.V., Vasianovich M.E. [Identification of the main dose-forming radionuclides in nuclear power plant emissions]. Atomnaya energiya [Atomic energy], 2016, vol. 120, no. 2, pp. 106–108 (in Russian)