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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 18:32 |
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Conference: Bucharest University Faculty of Physics 2017 Meeting
Section: Atomic and Molecular Physics. Astrophysics. Applications
Title:
Aluminum vessels model simulation and integration concept using MicroShield code for the dose and shields estimation for the VVR-S Nuclear Research Reactor, Bucharest Magurele
Authors:
Ioan IORGA (1,2)
*
Affiliation:
1) Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH), P.O. BOX MG-6, RO-077125, Magurele, Romania
2) Faculty of Physics, University of Bucharest, P.O.B. MG-11, 077125, Bucharest-Magurele, Romania,
E-mail
johnny@nipne.ro, johnny_tsk@yahoo.com
Keywords:
decommissioning, model simulation, dose rate, shields estimations
Abstract:
The VVR-S Nuclear Research Reactor owned by Horia Hulubei – National Institute for Physics and Nuclear Engineering (IFIN-HH), was built in Romania between: 1955 - 1957. The research reactor operated until 1997 and was permanently shut-down in 2002. During his life time, it was functional for a period of 113467 h, including 2000 h at 3.0–3.5 MW power. The total power output up to 1997 was 9.59 GWd. It had a utilization factor of 65 % (approximate 9510 effective days of operation) with an average of 1 MW thermal power. VVR-S means that is a thermal neutrons reactor model S moderately cooled and reflected with distilled water, fueled with enriched uranium 10% in the beginning and 36% subsequently. Neutron activated materials were by far the major contributor to the total inventory of radioactive reactor. Maximum values of dose rate at external aluminum vessel wall were between 3,5 mSv/h. and 9 mSv/h. Maximum values of the inner aluminum vessel near the active core were between 7,85 mSv/h. and 16,62 mSv/h in conformity with the location the experimental channels. Problematic dose rate appeared only on the vessels part that included reactor core – maximum value was 140 mSv/h at 10 cm, near thermal column inside the aluminum vessel,. Oher internal values vary between 400 µSv/h and 35 mSv/h at 10 cm from the wall. The principal radionuclides implicated were the 60 Co, 137 Cs, 152 Eu and 154 Eu with theirs correlation factors respectively. We needed to respect the radiation protection program the radiation dose limit is 20 mSv/year for the personnel professionally exposed, For this reason the simulation of the potential dose rate exposure and the shield calculation was necessary. Simulation accomplishment with reality was between 71,43% and 77,78% taken into account the integration of all data and asymmetry of the aluminum reactor vessels.
Acknowledgement:
VVR-S Nuclear Research Reactor decommissioning team for help collect the necessary data.
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