Identification and characterization of human actions within the framework of safety analysis and associated documents for a PWR nuclear power plant

This master’s thesis has been carried out during the internship at IDOM Nuclear Services. The thesis covers part of a project that IDOM is performing for a company that operates two nuclear power plants, henceforth, the client. The client has decided to adopt the Time Critical Action (TCA) / Time Sensitive Action (TSA) program as a part of his upgrade program iden- tified in their third Periodic Safety Review (PSR). The Program that wants to be adopted is the one designed by the Pressurized Water Reactor Owners Group (PWROG). This program es- tablishes the guidelines to identify, verify and maintain the validity of the TCA /TSA actions. The scope of this Master Thesis only covers the identification and characterization of the Time Sensitive Actions found in the Extensive Damage Mitigation Guides (EDMGs) for both plants, the Operator Manual Actions (OMAs) only for the NPP2 and the Probabilistic Risk Assessment (PRA) human actions for both plants. The client will be responsible for the validation phase. Within the project, the goal of this thesis is to deliver a set of technical sheets that provide the client all the information they need to join the PWROG program regarding the TSAs. The core of the project consists in two main blocks. The first block contextualizes and provides a theoretical basis for concepts used throughout the thesis. This point is necessary to be able to follow the subsequent explanations. The second block describes the methodology followed for the identification and characterization of the TSAs for each scope considered. Since each scope (EDMGs, OMAs or PRAs) has its particularities, the steps followed to analyze each of the scopes have been detailed in order to capture the difficulties and tasks performed. EDMGs have been the first scope addressed. Their identification has consisted on reading and understanding the guidelines for a subsequent selection of those that can be considered TSA. For their characterization, several reports have been reviewed so as to describe their bound- ary conditions. In cases where documents were not enough, even system engineers have been consulted to obtain the necessary information. In the case of OMAs, the identification and char- acterization of the actions was faster, since much of the information was already provided by the documentation delivered by the client, and in some cases it only had to be checked and extended. The PRAs analyses review has been, together with the EDMGs, the most demanding task. For this scope, a huge number of actions were identified as potential TSAs. In order to reduce the number of actions to be characterized to a manageable number a selection process has been carried out. The process of characterization of these actions has been similar to the previous scopes except for the information regarding the applicable procedures. The explanation of the methodology used to obtain the applicable procedures is attached in the annexes of this project. The results of this project are the technical sheets prepared with the information gathered after the analysis of all the documentation consulted. These data sheets will be the foundation for the implementation of phase two of the PWROG program by the client. In addition, during the project a set of documents have been prepared and delivered to the client in order to inform about some aspects to be clarified or improved in their documentation.