Measurement of high energy -ray spectrum accompanied by neutron induced fission of U, 2

Makii, Hiroyuki   ; Nishio, Katsuhisa   ; Hirose, Kentaro  ; Orlandi, R.  ; Ogawa, Tatsuhiko   ; Soldner, T.*; Hambsch, F.-J.*; Frost, R.*; Tsekhanovich, I.*; Petrache, C. M.*

The Japanese government has a plan to remove the melted reactor fuel for the full deconstruction of Fukushima I Nuclear Power Plants. The removal of the fuel must be carried out without reaching the criticality of the fuel. However, it is quite difficult to monitor the increased fission rate due to the background -rays from the fission products in the fuel. Here we are proposing to develop a system based on the use of the high energy -rays accompanied by fission. In order to design the system, it is essential to know the spectrum of prompt fission -rays up to more than 7 MeV for U(n,f) reaction. However, no data are available in the -ray energy range larger than 7 MeV. This prompted us to make a new measurement to extend the known prompt -ray energy spectrum up to 20 MeV. The measurement has been carried out at the PF1b beam line of the Institut Laue-Langevin. In this contribution, we will present the results obtained the measurement.