The Accelerator Driven Systems, a 21st Century Option for Closing Nuclear Fuel Cycles and Transmuting Minor Actinides

Closing the nuclear fuel cycle and transmuting Minor Actinides (M.As) can be considered as an application of the duty of care principlel principle which says that, “before the final disposal of any waste, any possible chemical and/or physical treatment has to be applied in order to reduce the waste’s toxicity, provided the treatment does not convey unacceptable risks or unacceptable costs”. Forty years of complex research and development has shown that Accelerator Driven Systems could provide a solution to the challenge posed by spent nuclear fuels, by enabling the ability to considerably decrease their radiotoxicity lifetime burden and volume. In particular, a multilateral strategy of treatment of the MAs could be a commendable solution for both the countries phasing out the exploitation of nuclear energy and for those pursuing and developing this exploitation. The pre-industrial assessment of the technical and financial feasibility for industrialization is the next step. This applies to the four R&D and Demonstration building blocks: advanced separation, MAs’ loaded fuel fabrication, dedicated transmuters demonstration (MYRRHA) and provision for MAs’ fuel loaded processing. A global vision of the process leading to a sustainable option is proposed.

Raman Spectroscopy Studies of TRISO-Particle Fuel

Development of High Temperature Gas-cooled Reactors opens new horizons for nuclear power in Poland. Good understanding of the failure-free performance of Tri-structural ISOtropic (TRISO)-particle fuel is a key for the safe and efficient operation of those reactors. It is also essential to avoid potential errors in TRISO fuel production for the HTR program in Poland. In a longer perspective to ensure the highest possible quality of the TRISO fuel fabrication and storage before loading into the reactor core, it is necessary to control the quality of the TRISO-particle fuel in order to understand the aging of fresh fuel. Nevertheless, such a solution requires to determine whether the passage of time affects the occurrence of changes in TRISO fuel layer’s structure and at the same time whether it contributes to increasing the probability of damage to the examined fuel material. For this purpose, it is planned to perform an experiment on different types of TRISO fuel, produced in different periods of time. The comparative analysis will be based mainly on the experimental method of Raman spectroscopy.

Thorium-based CANDU qualification as plutonium burner

Converting the weapon grade Plutonium from the U.S.A., Russia, U.K. etc. to Mixed OXide fuel and using it in power reactors was seen as a feasible way to both dispose Plutonium and produce energy. Using Thorium-based fuels in CANDU has been investigated since early 1980’s, they were designed and tested in Canada as mixed ThO2 -UO 2 (both LEU and HEU) and mixed ThO2 -PuO 2, (both reactor- and weapons-grade) ([1]). In this respect, Thorium might also be seen as a valuable driver for weapon grade Plutonium annihilation. Our goal was to investigate ThO2 -PuO 2 MOX in the aim to propose a suitable fuel for the existing and future CANDU units in Romania. Both weapon grade and reactor grade Plutonium were considered as fissile drivers for Thorium. Since this is only an exploratory study, some key design parameters such as fuel pellet density and ThO2 /PuO 2 ratio were considered to span over a certain range imposed by MOX fuel fabrication technology and limited Plutonium availability. Eighteen fuel compositions were considered and cell calculations were performed for 37 and 43-element bundles using several computer codes.