This is the announcement and call for presentations for the International Expert Workshop on the Investigation and Study of Suitable and Optimised Methods for Battery Capacity/Performance Tests and the Checking and Validation of Transmission System Design Assumptions and Models. The workshop is being organised under the auspices of the OECD Nuclear Energy Agency (NEA) Committee on the Safety of Nuclear Installation (CSNI)  Working Group on Electrical Power Systems (WGELEC). The workshop will be hosted by the Nuclear Regulation Authority (NRA), Japan, from 4 to 6 November 2025.

Working under the mandate of the CSNI, the main mission of the WGELEC is to advance the current understanding and address safety issues related to electrical systems that would support the continued safety performance of nuclear installations and improve the effectiveness of regulatory practices in NEA member countries. This activity aligns with the main goal of WGELEC to enhance the analysis techniques and robustness of electrical systems to ensure the continued safety of nuclear installations in member countries.

In response to a recognition of the technical and scientific needs, the Working Group of Electrical Power Systems (WGELEC) initiated two activities entitled the Investigation and Study of Suitable and Optimised Methods for Battery Capacity/Performance Tests and the Checking and Validation of Transmission System Design Assumptions and Models. The objectives of these two activities are as follows:

• The growth in larger battery systems in existing and new nuclear power plants, linked to the enhancements enacted after the Fukushima Daiichi NPS Station Blackout (SBO), means prolonged capacity / performance testing and an increasing burden on the operator during outage periods. The objective of this activity is to investigate actual practices and equipment used in battery capacity/performance tests and to identify good practices which provide operators and regulators with greater confidence in assuring intended safety functions.

• The worldwide commitment to achieving a net-zero carbon emissions target means transmission systems are undergoing significant changes. The objective of this activity is to undertake a review of how member states check and validate the impact on safety of transmission system design assumptions and models.

For both tasks, the first phase has been through a survey sent to members of WGELEC and the wider CSNI in order to gain an informed view on the understanding and approaches to these issues in member countries, identifying any common techniques and good practices.

The second phase of the tasks shall be to conduct this workshop, where subject matter experts can come together and discuss their experiences and concerns on the two topics. This electronic notification forms the official/early workshop announcement.

The workshop, which will be split into two consecutive sessions, is expected to help identify and characterise the topics, share good practices and identify whether further guidance or research is necessary to help understand the issues and improve the plant safety.

The focus of the workshop shall be on exchanging information in the two topics focusing on areas of concern from the assessment of the survey results, as well understanding the expectations and approaches, from a regulatory, operator or designer perspective. The workshop will provide an opportunity for nuclear safety specialists to share ideas for improving understanding and developing guidance on the two topics. To maximise the benefit of this workshop for all, attendees are encouraged to provide a short presentation on either their approach or experiences on one or both of the workshop topics.

The workshop will include introductory and technical sessions on each topic as well as a facilitated wrap-up session to capture the lessons learnt from the workshop. Active participation of the workshop attendees in the discussions as well as formulating conclusions and recommendations is highly encouraged and appreciated. Information obtained as a result of the workshop should provide a better understanding and improved interpretations of subjects, topics and issues related to safety.

Two activity reports, one for each task, will be prepared by the WGELEC activity leads capturing the survey results together with the workshop proceedings and conclusions and any recommendations for further work. These reports will be published on the OECD-NEA website.

Participants intending to give presentations related to the workshop topics shall submit an abstract (up to 500 words) that provides a brief overview of the content of their proposed presentation. All abstracts should be submitted by 31 August 2025 by filling in the Submission Form. The Organising Committee will review abstracts and notify the authors by 30 September 2025 on the acceptance of the presentations. Presentation slides should be uploaded on the event myNEA space or sent to Mr. Markus Beilmann (markus.beilmann@oecd-nea.org) by 17 October 2025.

The workshop is organised as in-person event. Please contact the NEA Secretariat in case of questions. 

Presentations addressing all issues and topics related to the two activities of the Investigation and Study of Suitable and Optimised Methods for Battery Capacity / Performance Tests and the Checking and Validation of Transmission System Design Assumptions and Models are requested.

The following topics are planned to be addressed at the workshop for each activity:

• Experience with battery capacity, performance and modified performance tests including practices, methods, workloads and/or issues;
• Novel approaches to the testing of batteries for checking capacity and/or capability;
• Regulatory environment related to the consideration of requirements;
• Management of transmission system design assumptions and models;
• Overall experiences, lessons learnt and recommendations on good practices; and
• Areas where guidance or further research is considered would be beneficial to improving safety.

The organisers kindly invite experts from industry, transmission system operators, battery manufacturers, regulatory authorities, technical support organisations (TSOs) and research institutes, safety analysis practitioners and consultants involved in safety assessment of nuclear power plants from participating countries to contribute and participate.

All participants have to register by 31 August 2025 by filling in the Registration Form. Please register via: Registration Form.

Please contact Mr Markus Beilmann (markus.beilmann@oecd-nea.org) by e-mail in case of questions or problems.

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