Research & Development

Molten Salt Reactors / NRG Completes Key Irradiation Test At Petten

By David Dalton
18 September 2019

NRG Completes Key Irradiation Test At Petten
The Petten HFR in North Holland. Photo courtesy NRG.
Netherlands-based nuclear services provider NRG has completed an irradiation test on molten nuclear fuel salts inside the High Flux Reactor (HFR) at Petten.

NRG said this is the first irradiation of its kind since research carried out in the US in the 1960s.

Irradiation tests are a crucial step in the development of molten salt reactor technology, which NRG said is promising in terms of both safety and economy, while having the potential to avoid the release of long-living radioactive waste in severe accident scenarios.

NRG said completing the test means it can now examine the irradiated salt more closely in its labs. “This means we’ll really be able to see how the salt responds to irradiation in the reactor,” a statement said.

The irradiation experiment was the first conducted by NRG as part of a molten salt reactor research programme that began in 2015.

The programme, partly funded by the Netherlands’ Ministry of Economic Affairs, has expanded considerably since 2015. It includes research into construction materials, processing and purification of molten salt, and processing residual products.

An irradiation scheduled for this autumn will investigate the radiolysis of salts, a process which can occur when nuclear fuel salts cool down to near room temperature while in a radiation field, resulting in the production of gases.

Early in 2020 NRG will start an irradiation experiment in the HFR to examine the corrosion resistance of candidate materials for the construction of a molten salt reactor. This will help bring molten salt reactors closer to reality, NRG said.

NRG is working with the European Commission’s Joint Research Centre in Karlsruhe, which has produced the salt samples and will assess the results with NRG after irradiation. Part of this post-irradiation assessment will be carried out in cooperation with a European research project known as Samosafer, which will be coordinated by Delft University of Technology.

Molten salt reactors are powered by a radioactive solution that blends fissionable isotopes with a liquid salt. They can run on uranium, but are also ideally suited for thorium, an alternative nuclear fuel resource that is cleaner, safer, and more abundant than uranium.

The International Atomic Energy Agency said molten salt reactors operate at higher temperatures, making them more efficient in generating electricity, while their low operating pressure can reduce the risk of coolant loss, a major accident risk. According to the IAEA, molten salt technology needs at least a decade of intensive research, validation and qualification before it can be commercialised.

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