DOSE ASSESSMENT FOR TYPICAL NPP-2006 STAFF FOR DESIGN BASIS ACCIDENT TAKING INTO ACCOUNT SITE INFRASTRUCTURE

Assessment of radiation effect on nuclear power plant staff was made for design basis accident. The considered accident scenario includes spent fuel assembly drop into the reactor core or fuel pool during load-unload operations with fuel assemblies damage and radionuclide emission. The proposed method included the assessment of radionuclide sedimentation on characteristic surfaces of nuclear power plant site, calculations of radioactive aerosol distribution depending on the distance of emission source in COMSOL 3.5 program. The software module is based on highly detailed account of the infrastructure of the nuclear power plant industrial site according to the master plan, which allows obtaining more accurate estimation of radioactive substances deposition and, as a result, more accurate calculation of doses for staff and population. The assessment of average volume activity in lower air layer on site during VVER design basis accident is performed. Doses from radioactive cloud (external exposure) and from inhalation (internal exposure) were estimated for following radionuclides: ¹³⁷Cs, ¹³¹I, ¹³³I, ⁹⁰Sr. In the case of the design basis accident associated with the fall of the assembly during fuel load-unload operations the received value of the total effective dose of staff exposure is 7.80 mSv for the first 8 hours after the accident beginning. This number is well below the threshold of the allowable annual dose limit for personnel in emergency situations (50 mSv).

1. Belozerskii G. N. Radiation ecology. Мoscow, Akademiya Publ., 2008. 382 p. (in Russian).

2. Bolshov L.А., Linge I. I. (eds.). Proceedings of IBRAE RAS. Issue 11: Radioecology Issues. Мoscow, Academy Publ., 2009. 444 p. (in Russian).

3. Pugliese S., Jaeger M., Occelli R. Finite element modeling of plume dispersion in the lower part of the atmosphere. Caussade B., Power H., Brebbia C. A. (eds.) Air Pollution. Monitoring, Simulation and Control. Southampton, Comp. Mech. Pub., 1996, pp. 99–108.

4. Andrizhievskiy А. А., Trifonov А. G., Kulik L. S. Analysis of transfer and deposition processes of aerosol particles on the characteristic surfaces of NPP infrastructure. Trudy BGTU. Ser. 3. Chimiya i tekhnologiya neorganicheskikh veschestv [Proceedings of BSTU. Chemistry and technology of inorganic substances], 2014, no. 3 (167), pp. 89–93 (in Russian).