Radiation-Hygienic Investigations of Experimental Production of Mixed NitrideUranium-Plutonium Fuel at JSC SChC. Part 2: Doses and Risks
Authors:   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Ilin L.A. , Samoilov A.S. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Tsovyanov A.G. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Shinkarev S.M. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Shandala N.K. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Gantsovsky P.P. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Karev A.E. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Kukhta B.A. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Simakov A.V. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Klochkov V.N. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Korenkov I.P. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Lyaginskaya A.M. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Parinov O.V. ,   A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia, Ivanov V.K. ,   A.F. Tsyb Medical Radiological Research Centre, Obninsk, Russia, Chekin S.Yu. ,   A.F. Tsyb Medical Radiological Research Centre, Obninsk, Russia, Menyailo A.N. ,   A.F. Tsyb Medical Radiological Research Centre, Obninsk, Russia, Tumanov K.A. ,   A.F. Tsyb Medical Radiological Research Centre, Obninsk, Russia, Solomatin V.M. ,   JSC «Proryv», Moscow, Russia, Izmestyev K.M. ,   JSC “Siberian Chemical Combine”, Seversk, Russia
Published: April 2022

Purpose: Assessment of the compliance of the radiation protection of workers at the complex experimental installations of JSC SChC with the requirements of the Russian radiation safety standards NRB-99/2009 to limit the generalized risk of potential exposure and the IAEA recommendations for not exceeding the control level of the minimum significant radiation risk. Materials and methods: The results of radiation-hygienic investigations of radiation exposure factors affecting workers involved in the manufacture of mixed uranium-plutonium nitride (MUPN) fuel at the complex experimental installations of JSC SChC are used as the input data for the preliminary assessment of radiation doses to workers. The models for assessment of radiation risk of potential exposure have been developed in accordance with the recommendations of the ICRP and the IAEA. Results: Preliminary estimates of the doses of external gamma-neutron (2.5 ± 0.5 mSv / year) and internal exposure of workers (~1 mSv/year1) are related to the current levels of exposure of workers of complex experimental installations. These levels are the result of exposure to ionizing radiation sources associated both with the development of new technologies and with residual radioactive contamination resulting from previous activities not related to the manufacture of MUPN fuel. The presented dose estimates are related to the use of raw materials that have undergone deep preliminary purification from radiogenic impurities. When irradiated nuclear materials are used as raw materials, the levels of gamma-neutron exposure to workers will be significantly higher. The maximum increase in the generalized risk of potential exposure due to annual exposure is estimated for women aged 18 years at the beginning of exposure, for which the increase in this risk is 1.45 × 10-4 year-1, which is 1.37 times lower than the limit established by the Russian radiation safety standards NRB-99/2009: 2 × 10-4 year-1. All predicted values of the lifetime attributable fraction of radiation (LARF) in mortality from malignant neoplasms are significantly less than the control level of the minimum significant risk recommended by the IAEA (LARF = 5 %), and the maximum value of LARF = 2.8 % is achieved for women aged 18 years at the beginning of exposure. Conclusion: Restrictions on the radiation risks of potential exposure, established by NRB-99/2009, as well as those recommended by the IAEA for not exceeding the reference level of the minimum significant risk, are met with a large reserve. The results obtained and the developed methods will be used to ensure the radiation safety of workers during the transition from experimental installations to pilot industrial implementation of the technology for the production of MUPN fuel.