Dismantling Prioritization of a Wide Variety of Facilities - IRSN Review of CEA Strategy - 23018

Nuclear licensees who are - or were - in charge of nearly every aspect of nuclear industry (research, waste management, defense, etc.) have to deal with a wide variety of facilities, such as reactors, accelerators and irradiators, laboratories as well as waste treatment and storage facilities, many of these being shut down or under decommissioning. Thus, the dismantling and decommissioning (D and D) of many facilities is an increasingly challenging topic, involving a lot of parameters and conditions to be considered. Managing all relevant factors, in accordance with the regulatory reference immediate dismantling strategy, can often be complicated when the goal is to achieve high levels of safety and optimize decommissioning scenarios, waste generation, costs and timelines, especially when licensees have limited budget and human resources. This led to important delays in carrying out the dismantling actions, especially for legacy waste recovery. Recognizing this, in 2015, the French national safety authorities for civilian and defense nuclear facilities (resp. ASN and ASND) asked to the Commissariat a l'energie atomique et aux energies alternatives (CEA), French major licensee, to prioritize future dismantling actions, to provide an analysis of the difficulties encountered up to then and to update its waste management strategy. In 2016, the CEA answered the authorities by sending a global decommissioning strategy report covering civilian and defense nuclear facilities (almost 40 facilities). In its report, the CEA developed a prioritization methodology based on a criterion considering radiological inventories characteristics, such as radiotoxicity, dispersibility or sensitivity to external aggressions. Accordingly, the safety authorities asked to the Institut de radioprotection et de surete nucleaire (IRSN), as their technical safety organization, to review the CEA decommissioning strategy. To support the review process, IRSN implemented its own analytical approach based on 3 axes: - definition of 'reasons for prioritization', assessing the dismantling actions priority level according to parameters such as the capability of the facility to withstand external aggressions, the existence of a developed urbanization nearby the facilities, etc., - definition of 'critical assets', considering the elements required to perform and achieve the dismantling actions (such as authorizations required, availability of waste treatment support facilities or transport packages, etc.), - global prioritization of dismantling actions. This paper presents IRSN's methodology, including limits that can be identified, and some results. It will be shown that such approaches are useful tools for comparing safety issues among widely different types of nuclear facilities under decommissioning. (authors)