Concept of a BNCT line with in-pool fission converter at MARIA reactor in Swierk

BNCT facility in the Institute of Atomic Energy in Otwock-Swierk is under construction at the horizontal channel H2 of the research reactor MARIA. Measurements of the neutron energy spectrum performed at the front of the H2 experimental channel, have shown that flux of epithermal neutrons (above 10 keV) at the BNCT irradiation port was below 10⁹ n cm^-2 s^-1 i.e. it was too low to be directly used for the BNCT treatment. Therefore, a fission converter will be placed between the reactor core and the periphery of the graphite reflector of MARIA reactor. The uranium converter will be powered by the densely packed EK-10 fuel elements with 10% enrichment. Preliminary calculations have shown that the total neutron flux in the converter will be about 10¹³ n cm^-2 s^-1 and flux of epithermal neutrons at the entrance to the filter/moderator of the beam will be about 2·10¹³ n cm^-2 s^-1.