IAEA finds improved safety at Dutch research reactor

23 April 2024

The operator of the Hoger Onderwijs research reactor in the Netherlands has enhanced safety since a previous review mission in September 2021, a follow-up International Atomic Energy Agency (IAEA) mission has concluded.

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

The previous Integrated Safety Assessment for Research Reactors (INSARR) found that the Reactor Institute Delft (RID) at the Delft University of Technology had prioritised safety during implementation of significant refurbishment and modernisation of the facility. The team also found areas requiring further enhancements, including the organisational structure and safety procedures and documentation.

An 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 follow-up INSARR mission to the Hoger Onderwijs reactor was requested by the Dutch regulatory body, the Authority for Nuclear Safety and Radiation Protection.

A team has now completed the follow-up INSARR mission. While it concluded that safety had since been enhanced through the implementation of the previous recommendations, the team found there is the need to address recommendations related to operational radiation protection and commissioning, following major modifications to the research reactor.

Earlier this month, the 3 MWt pool-type research reactor ended a six-month shutdown for the installation of a cold neutron source, which uses very low energy neutrons to study materials with large dimensions. It has since resumed operation to complete the commissioning of the cold neutron source.

The team assessed that RID has strengthened the organisational effectiveness and operational programmes through: completion of an analysis for RID organisational restructuring options and clarification of roles and responsibilities; revision of operational limits and conditions, with clear distinctions between safety limits and safety system settings; development of an asset management database for the reactor operating programmes and technical modifications; and improvement of emergency preparedness by conducting drills.

The findings from the mission indicate the need for continued safety enhancements in areas that are related to: reassessment and development of a specific set of operational limits and conditions associated with the commissioning stages of testing the new installation of the cold neutron source; and revision of the area classification and zoning systems for radiological protection, considering the laboratories located within the reactor site.

"RID has addressed most of the review recommendations made in 2021 and achieved significant safety enhancement," said Kaichao Sun, mission team leader and Nuclear Safety Officer at the IAEA. "Efforts remain needed to ensure the highest level of safety during the ongoing commissioning tests, following the recent major modifications at the Hoger Onderwijs reactor."

"This INSARR follow-up mission effectively improved the safety awareness," said Camiel Kaaijk, Head of the Reactor Development Department. "In particular, the extensive and detailed discussions on the safety assessment gave us new insights on this topic."

The Hoger Onderwijs 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. It was temporarily shut down in 2019 for the modification programme of its systems and components, including cooling circuits and the containment dome.

Researched and written by World Nuclear News