Recommendations for improved calculational-experimental evaluation of radiation load parameters on VVER reactor type equipment

Recommendations for improved calculational-experimental evaluation of radiation load parameters on VVER reactor type equipment.

Borodkin P. G., Khrennikov N. N.

An important condition for justification and extension of VVER non-restorable equipment (reactor pressure vessel, reactor support structures) lifetime is to confirm the reliability of radiation load parameters (neutron fluence, number of displacements per atom) used to justify the residual life-time. Estimation of the radiation load parameters on the equipment is based on the results of the neutron-transport calculations, carried out by the engineering methods. Another important issue is to get reliable experimental data to confirm the calculation methods used for estimation of the radiation load parameters on the VVER equipment.

This paper shows approaches of the calculational-experimental estimation of the radiation load parameters taking into account all uncertainties of the calculation and measurements. Such estimation is based on the results of neutron activation ex-vessel measurements. The proposed calculational-experimental analysis allows to get improved estimation of the parameter which can be used in the equipment conditions assesement.

The paper presents new estimation of the radiation load parameters on VVER equipment and shows the neutron field parameters distributions on different VVER equipment. Based on the results of such investigations some recommendations are proposed for additional approaches in radiation load monitoring on the VVER equipment.

Keywords: VVER equipment, radiation load, uncertainty, calculations, measurements.

Article language: Russian. Pp. 5–18. DOI: 10.26277/SECNRS.2022.103.1.001.