The decommissioning Concept for WWR-M research reactor is developed to meet the requirements of the current Ukrainian legislation. The main goal of the Concept is to provide a strategic stage of the work planning, including all the required justifications with a sufficient level of detail. It will allow during the next planning stage to develop the decommissioning project and other documents required to obtain the decommissioning license. The Concept is the institutional and technical document, which defines and substantiates the basic administrative, organizational, and technical measures for the preparation and implementation of the reactor decommissioning. It also describes the main activities and works, defines the procedure, conditions for their implementation and provision, and planned deadlines.

The WWR-M is a light-water-cooled and moderated heterogonous research reactor with a thermal output of 10 MW. The reactor has been in operation for >50 y and has had an excellent safety record. A non-hermeticity of the inlet line of the primary cooling circuit (PCC) was found, and the only reasonable technical solution was the complete replacement of the PCC inlet and outlet pipe lines. Such a replacement was a challenging technical task due to the necessity to handle large size components with complex geometries under conditions of high-level radiation fields, and therefore, it required detailed planning aiming to reduce staff exposure. This paper describes the dismantling and removal of the PCC components focusing on radiation protection issues.

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.