TOWARDS MODELLING DEFECTIVE FUEL RODS IN TRANSURANUS: BENCHMARK AND ASSESSMENT OF GASEOUS AND VOLATILE RADIOACTIVE FISSION PRODUCT RELEASE
L. Giaccardia, M. Cherubinia, G. Zullob, D. Pizzocrib, A. Magnib, L. Luzzib
a Nuclear and INdustrial Engineering (NINE), Via della Chiesa XXXIII 759, 55100, Lucca, Italy
b Politecnico di Milano, Department of Energy, Nuclear Engineering Division, Via La Masa 34, 20156, Milan, Italy
ANNALS OF NUCLEAR ENERGY, volume 197, March 2024, Article number 110249
Abstract —This work presents the results of a collaborative benchmark activity between different organizations towards the use of the TRANSURANUS code to estimate the release of gaseous and volatile radioactive fission products from defective fuel rods, into the primary coolant of pressurized water reactors. First, the radioactive release from the fuel to the gap is evaluated according to three approaches: the coupling between TRANSURANUS and SCIANTIX, the development of TRANSURANUS devoted subroutines, and the use of the ANS 5.4-2010 methodology. Fuel-to-gap release calculations are benchmarked and assessed against measured data from the CONTACT1 irradiation experiment. Then, TRANSURANUS has been used to estimate the radioactive release into the primary coolant by applying a first-order phenomenological rate theory and tested against measured data of fission product coolant concentrations from irradiation experiments of the CRUSIFON program.
PRELIMINARY SAFETY ANALYSIS AT THE DECOMMISSIONING OF THE WWR-M RESEARCH REACTOR
Yu. M. Lobach1, S. Yu. Lobach2, V. M. Shevel1
1 Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, Ukraine
2 Nuclear and INdustrial Engineering (NINE), Via della Chiesa XXXIII, 759, Lucca, Italy
АТОМНА ЕНЕРГЕТИКА ATOMIC ENERGY, Volume 110609, March 2020
Abstract — Following the demands established by the current Ukrainian legislation, the Decommissioning Concept for the WWR-M research reactor was recently approved. The Concept envisages a strategy of immediate dismantling; it identifies and justifies the main technical and organizational measures for the preparation and implementation of decommissioning, the sequence of planned works and activities, as well as the necessary conditions and infrastructure. Decommissioning requires proper planning and demonstration that all planned dismantling works will be carried out safely. Presented safety assessment is a mandatory component of the Concept and the most important element of the overarching technological scheme. The purpose of the safety analysis is to provide input for detailed planning on how to ensure safety during decommissioning. Based on the results of the safety analysis, the measures to ensure radiation protection are defined while justifying their necessity and sufficiency.
ASSESSMENT OF THE DOSE LOADDURING THE DISMANTLING OF THE WWR-M REACTOR
Yu. M. Lobach1, S. Yu. Lobach2, E. D. Luferenko1, V. M. Shevel1
1 Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, Ukraine
2 Nuclear and INdustrial Engineering (NINE), Via della Chiesa XXXIII, 759, Lucca, Italy
ЯДЕРНА ФІЗИКА ТА ЕНЕРГЕТИКА / NUCL. PHYS. AT. ENERGY 23 (2022) 234-244
Abstract — The WWR-M is a light-water-cooled and moderated heterogeneous research reactor with a thermal output of 10 MW.The final decommissioning planning is in progress now. The general decommissioning strategy consists of the dismantling and separate removal of the bulky elements as a whole (in one piece) without preliminary segmentation. The dismantling of the primary and secondary cooling loops is considered as one of the key tasks; a separate dismantling design has been developed. The baseline principles for the technical solution and safety are presented in the given paper. Results of the dose assessment showed that the work can be performed at a collective dose of less than 20 man-mSv.Keywords: WWR type research reactor, decommissioning, cooling loops, dismantling, exposure dose.