High Flux Reactor Continued Safe Operation: Time Limited Ageing Analyses

The High Flux Reactor (HFR) is a multipurpose nuclear reactor located in Petten, the Netherlands. With its 45 MWth it is one of the most powerful and versatile research reactors in the world. Its main roles are material irradiation and medical isotopes production. The output of the reactor in terms of medical isotopes is important at a global level (60% of European demand). Every day in the Netherlands alone 30.000 patients are treated using isotopes produced in the HFR. The importance of the HFR dates back in time. The HFR has been in service since 1961. Due to the long life (58 years to date) of the reactor an efficient integrated ageing management program (AMP) is envisaged as it is foreseen that the HFR will continue to operate for a prolonged period of time. The development of the AMP has begun in 2018 (CSO project) and will be completed in view of the IAEA CSO mission. The HFR is the second reactor in the world to undergo this type of IAEA review and one of the objectives of this project is to set a state of the art when it comes to research reactors long term operation. The CSO project foresees four major sections: scoping and screening, development and improvement of plant programs, (re) validation of time limited ageing analyses (TLAAs) and realization of the ageing management program. In this paper the focus will lie on the TLAAs. The applicable TLAAs were scoped starting from the IGALLs TLAAs list. The TLAAs relevant for the HFR are: TLAA fatigue, TLAA reactor vessel, TLAA leak before break, TLAA manufacturing flaws TLAA beryllium and TLAA equipment qualification. The latter was developed in the framework of the equipment qualification plant program and does not figure as an independent TLAA in the CSO project. For each TLAA the principal problematics will be highlighted and the possible solutions illustrated.