Design Concept of the Thermal Flux Island in MYRRHA for LLFP Transmutation. Present Status.

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MYRRHA is an ADS aimed at providing protons and neutrons for various R&D applications. It consists of a proton accelerator coupled to a sub-critical fast core. While the fast neutron spectrum, obtaining in the MYRRHA core, allows the transmutation of minor actinides (MAs), the transmutation of long lived fission products (LLFPs) in MYRRHA requires the utilisation of a thermal spectrum in order to take profit of the fact that the capture cross-sections of the LLFPs are much larger in the thermal-energy domain than in the high-energy domain. A high thermal flux island inside MYRRHA is therefore being developed, consisting of an irradiation device for LLFPs (or other irradiation target material needing a thermal neutron spectrum), surrounded by assemblies filled with a lattice of ZrH2 moderator pins, cooled by the same coolant (Pb-Bi) as the MYRRHA fuel assemblies. Thermal neutron absorbers at the periphery of the neutron island are used to minimise the influence of the thermal flux on the fast core. The study of the performances of MYRRHA, including the transmutation of the LLFPs in such a thermal island, is carried out with the aid of the code MCNPX. The transmutation performances of LLFPs are assessed by coupling the code MCNPX to an evolution calculation. The LLFPs studied are Tc-99 and I-129.


Original languageEnglish
Title of host publicationANS Topical meeting on accelerator applications accelerator driven transmutation technology application - CD ROM
PublisherANS - American Nuclear Society
Number of pages7
ISBN (Print)0894486667
Publication statusPublished - 14 Nov 2002
Event2001 - AccApp/ADTTA : Fifth International Topical Meeting on Nuclear Applications of Accelerator Technology - Reno, United States
Duration: 11 Nov 200115 Nov 2001


Conference2001 - AccApp/ADTTA
Country/TerritoryUnited States


  • LLFD (long lived fission products), transmutation of waste, thermal island, ADS MYRRHA

ID: 4784962