Facility to replace High Flux Reactor and secure isotope supply for Europe
Construction has officially begun of the Netherlands’ new Pallas research reactor, which will replace the High Flux Reactor (HFR) in Petten, developer NRG Pallas said.
In July 2025, the reactor-related section received the green light from the Dutch ministry of health, welfare, and sport after preparatory works, including site preparation and delivery of the construction pit, were completed.
On 29 September, Anita van den Ende, the ministry’s secretary-general, formally launched the start of construction, a statement said.
In May 2025, workers completed the construction pit and its concrete foundation. Work on the pit began in 2023. Next construction stage would include work on the lower section of the reactor.
Every day, more than 30,000 patients rely on the production of medical radioisotopes from the existing High-Flux Reactor (HFR) at Petten. This number is expected to increase with the introduction of new treatments using medical isotopes from reactors and the growth of patients with cancer and cardiovascular diseases worldwide.
In 2012, the Dutch government and the province of Noord-Holland decided that the HFR should be replaced to ensure the supply of medical radioisotopes and the continuation of nuclear research.
Last year, the European Commission approved the Dutch government’s €2bn ($2.3bn) measure to provide public support for the construction of the Pallas reactor.
Programme director Peter Dijk said the move into the construction phase followed years of careful preparation, state support, and financing agreements.
“We are proud of what we have achieved together and what we are yet to achieve: building a reactor in the construction pit,” he said.
The Pallas reactor is of the pool-type design, with its core placed in a large water pool that naturally provides neutron moderation and shielding. With a thermal capacity of about 55 MWt, it will surpass the 45-MWt HFR in Petten, offering improved neutron flux for medical isotope production.
