Technical Evaluation Results Concerning Hamaoka Nuclear Power Station Unit 4's Aging State (Follow Up)

(Note 1) A technical evaluation of an aging state involves identifying, from all aging degradation events that might or have occurred on safety function-equipped components/structures, incidents to focus on for the sake of countering age-related deteriorations, and in turn assessing the integrity of components/structures corresponding to these events. The evaluation process also includes checking if the present maintenance management is effective, and, when necessary, identifying maintenance measures that should be added. The evaluation, conducted on the assumption that the Unit will retain its cold shutdown, refers to a technical evaluation of an aging state for components/structures that feature safety functions and are necessary for maintaining a cold shutdown, and is also defined in the Implementation Guidelines. (According to the Implementation Guidelines, "The evaluation of an aging state shall be conducted only on the assumption of maintaining cold shutdown if any of the components/structures do not comply with the criteria specified in the Technical Standards for Commercial Nuclear Power Reactors and their Ancillary Facilities on the day that marks 30 years since the start of operation.")

(Note 2) "Ordinances" refer to "Article 43, Paragraph 3-22-1 of the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors," "Article 82 of the Rule for the Installation, Operation, etc., of Commercial Nuclear Power Reactors," and "Guidelines in Implementing Measures for Aging Management at Commercial Nuclear Installations."

• "Article 43, Paragraph 3-22-1 of the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors"
  As per the NRA regulations, this ordinance mandates to take steps required in achieving operational safety (this includes items concerning steps to take in the event of severe accidents) with regard to the maintenance of nuclear power reactor facilities.
• "Article 82 of the Rule for the Installation, Operation, etc., of Commercial Nuclear Power Reactors"
  This ordinance mandates technical evaluations to be conducted on the aging degradation of components/structures prescribed as critical in ensuring the safety of nuclear power reactor facilities by the NRA, and be completed by the day on which the nuclear reactor marks its 30th year of operation. The ordinance also requires harnessing the evaluation results to draw up a policy for maintenance management that must be performed within 10 years for relevant nuclear power reactor facilities.
• "Guidelines in Implementing Measures for Aging Management at Commercial Nuclear Installations" (hereinafter "Implementation Guidelines")
  This ordinance prescribes basic requirements for both aging state technical evaluations that are performed by reactor licensees to counter aging, as well as the Long-Term Maintenance Management Policy.
  
1. Performing and reviewing the technical evaluation of aging states
2. Drawing up and changing the Long-Term Maintenance Management Policy
3. Reflecting the Long-Term Maintenance Management Policy into Technical Specifications, and taking other steps
4. Performing maintenance management based on the Long-Term Maintenance Management Policy

(Note 3) The Long-Term Maintenance Management Policy is a plan for the maintenance management of relevant nuclear power reactor facilities; it must be implemented within 10 years after the 30th year since the start of operation, based on the results of technical evaluations on the aging state.

(Note 4) Partial and further amendments to the application pertaining to the Technical Specifications for Nuclear Reactor Facility entail reviews and description optimizations of some evaluation conditions, regarding the annexed table and attachment of the application for approval of changes associated with the Technical Specifications for Nuclear Reactor Facility, submitted on July 29, 2022.