Innovative nuclear fuel product for reduction of fuel cost in commercial reactors and small modular reactors

The goal of the research project is to develop a new innovative nuclear fuel product to increase cycle length, improve safety, save natural resources and hence reduce cost in commercial nuclear reactors, extend life time of nuclear reactors and increase availability in nuclear reactors. The aim is to use the product in commercial PWRs (Pressurized Water Reactor). PWR is the most common type of commercial nuclear reactors in the world (about 70 % of the installed capacity in commercial reactors worldwide is PWR). The most common PWRs have typically between 1000 MWe and 1500 MWe. The new nuclear fuel product will be simple enough to be licensed and compelling enough from both a commercial as well as a safety point of view. It has the potential to increase the cycle length by approx. 5 % in existing PWRs, and thus minimize the number of outages and reduce the time reactor not generate electricity. The new nuclear fuel product will minimize the neutron radiation to the reactor vessel and could extend the lifetime of a reactor. The new nuclear fuel product will also save about 3 % of the needed natural uranium. Moreover, the new nuclear fuel product enables more flexible reactor operation, which is crucial for utilities for safe and stable operation. One of the biggest challenges is to increase the cycle length whilst meeting all safety requirements set by the regulators, such as maximum pin peak power and maximum burnup. It requires multidiscipline research and development aspects to cover all the regulatory requirements. Experiments will be performed to verify the results as part of the licensing to demonstrate the safety to regulators. Thor Energy has applied for a patent for the new product and have a clear patent strategy to support the decision on applying more patent ideas in the future. The crucial thermal hydraulic and material experiment is planned to start in Q2 2020. Moreover, market research has showed promising results for the end user as well as selecting the first most probably end user. The partners in this project have long nuclear fuel experience in international cooperation. One of the partners is a fuel vendor that has a deep insight on the fuel manufacture requirements, customer needs, calculation tools and national regulations. Simulations in a real reactor is about to start now. The technical part of the project has been going according to plan and there has been no technical obstacles identified so far for utilizing ThX in todays commercial PWRs. The challenge however, is that the product does not seem to meet the expectations regarding uranium saving and accordingly the product is not as economical viable as expected. Due to this result Thor Energy has decided to terminate the project by the end of Q2 2020.

The ThX device/invention was intended to improve fuel efficiency in todays fuel and todays reactors. In the end, the effects were proven too marginal to be economically worthwhile to be introduced in a commercial framework. The fact that a patent was granted, proves the "innovation height" and novelty of the thinking behind this product, and indeed it did introduced a completely new concept in a PWR-core, the idea of i) separating neutron absorbtion material and fuel material, ii) utilizing unused control rod guide tubes as a host for fuel/absorbtion materials. The project has given valuable insight and knowledge of new ways of utilizing and operating a PWR, despite not being commercially viable in todays context, it serves as a concept and bases for future development with potentially new safety regimes and more pressure on developing commercial operating margins.

The objective is to develop a new nuclear fuel product to increase cycle length, improve safety, save natural resources and reduce fuel cost in commercial nuclear reactors by utilizing uranium and burnable absorber. The new nuclear fuel product will be simple enough to be licensed and compelling enough from both a commercial as well as a safety point of view from the perspective of end user. It is anticipated to increase cycle length by 5 % and save 2-5 % of the needed natural uranium in existing light water reactors (LWR). One of the biggest challenges is to minimize the need of natural uranium whilst meeting all safety requirements set by the regulators. It will require detailed calculations in neutronics, thermal hydraulics and mechanical. Moreover, experiments will be performed to verify the results as part of the licensing to demonstrate the safety to regulators. There will be two partners in this project, both with long and broad experience from international cooperation.