Determining of changing austenitic stainless steel elements content in the inner parts of VVER-440 reactor during operation

Neutron activation induces the element transmutation in materials surrounding the reactor active core. The objective of present paper is to calculation evaluate the change of austenitic stainless steel 08Ch18N10T elements content through neutron induced activation, in inner parts of VVER-440 reactor adjacent to the active core - in the baffle and in the barrel. Particularly the content change of Mn in austenitic stainless steel. First has to be calculated the neutron flux density and then the neutron activation of austenitic stainless steel elements in parts adjacent to the active core. Neutron activation represents a measure of austenitic stainless steel elements transmutation. The power distribution is determined like an average value of several cycles power distribution in the middle of cycle duration for NPP Dukovany. The power distribution is calculated with code MOBY-DICK [1]. The neutron flux density is calculated with code TORT [2]. The neutron activation of austenitic stainless steel elements in the baffle and in the barrel is calculated with system EASY-2007 containing the code FISPACT-2007 [3]. The calculation of changing austenitic stainless steel elements content is performed dependently on time until supposed end of reactor operation - 40 years. There is also necessary monitoring and benchmarking of steel element content changing, because the neutron flux calculation, particularly in thermal region, shows considerable uncertainty, e.g. [4]. The motivation for this work are studies target to stress corrosion cracking of austenitic stainless steels induced by radiation inside PWR and BWR, e.g. [5]. The paper could be a suggestion to estimation of austenitic stainless steel corrosion damage induced by neutrons in inner parts of VVER-440 reactor. (author)