Safety Reviews of Technical System Modifications in the Nuclear Industry

Abstract: The function of safety reviews (here understood as expert judgements on proposals for design modifications and redesign of technical systems in commercial Nuclear Power Plants, supported by formalised safety review processes) plays a fundamental role for safety in nuclear installations. The primary aims of the presented case studies includes: critically examining and identifying the main areas for improvement of the existing technical safety review process as it is conducted at a Swedish nuclear power plant, developing a new process, and evaluating whether any improvements were accomplished. By using qualitative methods, observation/participation and interviews, data has been gathered on how the safety review process is perceived and conducted by experts involved in the safety review process, and ways to improve this process have been developed. This area is neglected in the larger safety literature. The novel approach here is to gather data directly from those involved in the safety review process, analysis of safety review reports as well as from inspection reports by the regulatory authority.The study presented in paper I shows that the partition between primary and independent review is positive, having supplementary roles with different focus and staff with different skills and perspectives making the reviews. The study identifies a number of areas for improvement, such as: - a tendency to put too much resource on minor assignments - a clearer prioritization would improve focus on the most critical projects - there is a need for improved guidance and direction for how to structure the work It is argued that future applications of safety review processes should focus more on communicating and clarifying the process and its adherent requirements, and improve the feedback system within the process. It is also recommended that the NPPs create introductory training for new reviewersThe study presented in paper II concluded that grading of the primary safety review reports facilitates improved experience feedback by providing easier access to good examples for reviewers. Improvements identified by implementing the revised process are primarily linked to the independent safety review function, including better planning and means for resource allocation as well as clearer and more unambiguous supporting instructions. Introduction of formalized independent review meetings provides increased exchange of knowledge and strengthened the independent safety review function in the organization.