Construction of the PALLAS reactor in in Petten, North Holland, is now set to begin construction after being given a green light by Anita van den Ende, Secretary-General of the Ministry of Health, Welfare & Sport.
The 55 MWt tank-in-pool PALLAS research reactor will replace the existing 45 MWt High Flux Reactor (HFR), which began operating in September 1960. It was originally used for materials testing but is currently used for fundamental research and the production of medical radioisotopes. The reactor is operated by NRG on behalf of the European Union’s Joint Research Centre. It supplies some 60% of Europe’s and 30% of the world’s use of medical radioactive sources. PALLAS will be able to deploy its neutron flux more efficiently and effectively than the HFR.
Funding for PALLAS was allocated by the Netherlands Government even before a formal decision on its construction was made. Preparatory work on the foundation began in May 2023 before a construction licence was issued later in the year. In 2024 the European Commission approved government plan to invest €2bn ($2.2bn) in the reactor under EU state aid rules. In May, NRG-PALLAS announced that the building of the construction pit and the foundation for the reactor had been completed.
The first phase of the reactor construction will include three underground floors. Construction of the PALLAS-reactor building has already begun with the preparatory works in the construction pit. The perimeter of the future reactor building has been marked, a protective membrane installed, reinforcement bars placed, and an 8 cm concrete layer poured. To support heavy lifting and material delivery during construction, three tower cranes will be in operation. Foundations for all three cranes have been completed, and the first crane is currently being assembled.
The secondary cooling system building is part of the reactor secondary cooling system. This isolated system contributes to cooling the reactor by circulating water extracted from the Noordhollandsch Kanaal (inlet pipelines) and disposed to the North Sea (outlet pipelines). Preparations are progressing for the installation of the pipelines.
Retention walls, put in place over the summer using the Cutter Soil Mix (CSM) technique, now form the construction pit’s perimeter enabling excavating the area to construct the building. Since late August, drilling has been underway for 327 micro-piles – 30-metre-long steel piles filled with grout, and designed to support the future secondary cooling system building.
“Every day, thousands of patients depend on medical isotopes produced in Petten for their diagnosis or treatment,” said Maurits Wolleswinkel, NRG PALLAS CEO. “With the construction of the PALLAS-reactor to replace the High Flux Reactor, we are ensuring security of supply of medical isotopes in the future. This will make the Netherlands and Europe less dependent on other countries. Developments in the field of therapeutic isotopes are very promising. We want to contribute to better and more efficient patient care through the development and production of new isotopes.”
Peter Dijk, PALLAS Programme director said the PALLAS-reactor is a major infrastructure project and requires careful preparation. “Together with the Ministry of Health, Welfare & Sport, we have gone through all the steps to become a state-owned company and to secure financing. Together with our construction partner FCC and design partner ICHOS, we have reached the point where construction of the reactor building can begin. We are proud of what we have achieved together and what we are yet to achieve: building a reactor in the construction pit.”
