IAEA assesses safety of upgraded Dutch research reactor

20 September 2021

The Reactor Institute Delft (RID) at the Delft University of Technology, the operator of the Hoger Onderwijs research reactor in the Netherlands, has prioritised safety during implementation of significant refurbishment and modernisation of the facility, according to an International Atomic Energy Agency (IAEA) team of experts. The team also found areas requiring further enhancements, including the organisational structure and safety procedures and documentation.

The HOR research reactor core during operation (Camiel Kaaijk/RID)

An IAEA Integrated Safety Assessment of Research Reactors (INSARR) mission is conducted at the request of an IAEA Member State. It is a peer review service that assesses and evaluates the safety of research reactors based on IAEA safety standards. The INSARR mission to the Hoger Onderwijs reactor (HOR) was requested by the Dutch regulatory body, the Authority for Nuclear Safety and Radiation Protection (ANVS).

The HOR - a 2 MWt pool-type research reactor - is mainly used for research in nuclear science and engineering, neutron activation analysis and in the development of new radioisotopes and production methods. The RID was designated as an IAEA Collaborating Centre in 2010 and its stable isotope tracer methods contribute to IAEA activities in forensic sciences.

The reactor began operating in 1963 and since then has gone through several modifications. These included a conversion from highly-enriched uranium to low-enriched uranium fuel in 2005 and the refurbishment of nuclear instrumentation and control systems in 2010. The reactor has gone through periodic national safety reviews in 1999, 2010 and 2021. The HOR was temporarily shut down in 2019 for the modification programme of its systems and components, including cooling circuits and the containment dome.

A seven-day INSARR mission to assess the safety of the reactor concluded on 14 September. The team comprised four experts from Argentina, Belgium, Czech Republic and Slovenia, as well as three IAEA officials. The mission covered regulatory supervision and the organisational and management arrangements in place. It also reviewed technical areas, including safety analysis, operation and maintenance programmes, radiation protection, and safety of utilisation and modifications.

The IAEA team noted the effective implementation of administrative and technical measures to ensure safety despite COVID-19 constraints during the modification project. It also observed a commitment to safety in areas such as periodic safety reviews and ageing management.

The mission team made recommendations and suggestions for improvements, including: strengthening the organisational structure for operation by clarifying roles and responsibilities for safety to avoid potential conflicts of roles and duties; improving the programme for restart of the reactor operation after the prolonged shutdown period by retraining reactor operating personnel and updating reactor safety documents and operating procedures to reflect recent modifications; and enhancing ageing management by addressing obsolescence of systems and components and by using feedback from the reactor operation and safety assessments.

"The RID has shown a strong commitment to safety during implementation of the refurbishment and modernisation of the reactor's systems and components," said David Sears, Senior Nuclear Safety Officer of the IAEA's Research Reactor Safety Section. "The RID is expected to extend these efforts to ensure safety during the ongoing commissioning of these modifications and throughout the process to restart the reactor, scheduled for later this year, after a prolonged period of shutdown."

"We appreciate the IAEA's support, especially considering the constraints imposed by COVID-associated restrictions," said Bert Wolterbeek, the HOR reactor manager and director of the RID. "The INSARR mission provided us with valuable recommendations and suggestions for further improvement of operational safety, safety culture and safety management; we are committed to implementing them."

RID intends to request a follow-up INSARR mission in 2023.

Researched and written by World Nuclear News