Design and burn-up analyses of new type holder for silicon neutron transmutation doping

Komeda, Masao   ; Arai, Masaji ; Tamai, Kazuo*; Kawasaki, Kozo*

We designed and fabricated a new type holder that achieved uniform doping under long-term use at JRR-3. The new type holder uses an aluminum alloy and BC particles as filter materials to ensure uniform vertical flux distribution. Although the amount of filter material decreases with long-term use, it was found that the doping distribution did not change by much until 800 h. The lifetime of the new type holder (of the order of hundreds of hours) depends mainly on the amount of trapped radioactive isotopes. This indicates that the decrease in filtering ability over the filter's lifetime is not significant. The filtering ability remains stable for a long time, and the difference in the vertical doping distribution is 1.08 at 1600 h and 1.18 at 4000 h. The irradiation efficiency is expected to increase by 1.7 times when using the new type holder.