Experimental studies on water radiolysis by alpha rays from plutonium 239 in solid materials, 1; The Energy spectrum of alpha rays emitted from the solid material powder

Nagaishi, Ryuji ; Ito, Tatsuya  ; DiPrete, D.*; Fellinger, A.*

In the 1F decommissioning, the retrieval of fuel debris is planned, and then the importance of water radiolysis by alpha-rays becomes increasing in the debris storage more than 10 years after the accident. When alpha-emitting nuclides are contained in insoluble solid materials, the alpha-rays slowdown in the materials, and the energies of alpha-rays escaped from the materials become lower and continuous. The energy spectrum varies with the type and size of materials, and this spectral difference affects the pattern and magnitude of G-value of water radiolysis. Therefore, in order to study the alpha-radiolysis, it is necessary to measure and evaluate the material-dependent spectrum. In this study, we used solid material powders containing plutonium 239 (Pu-239) and measured the alpha-ray spectrum from the powders to estimate the linear energy transfer (LET) of alpha-rays. It was further compared with that when the nuclide is a dissolved species in water.