[1A05-07] Radiolysis, Corrosion 2

[1A05] 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

*Ryuji Nagaishi¹, Tatsuya Ito¹, David DiPrete², Andrew P. Fellinger² (1. JAEA, 2. Savannah River National Laboratory)

Keywords:Plutonium 239 (Pu-239), Fuel Debris, Solid Material, Alpha Ray, Energy Spectrum, Linear Energy Transfer (LET), Water Radiolysis, Radiation Quality (LET) Effect

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. When alpha-emitting nuclides are contained in insoluble solid materials such as the debris, the alpha rays emitted with nuclide-specific energy slow down in the materials, the energies of alpha rays escaped from the materials become lower and continuous, and then the alpha rays would cause water radiolysis. The energy spectrum of alpha rays varies with the type and size of materials, and this spectral difference affects the pattern and magnitude of G-value of water radiolysis. Therefore, 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 Pu-239, which emits alpha rays with a single energy and high specific activity, and measured the alpha-ray spectrum from the powders. The LET of alpha rays was estimated from the spectrum and compared with that when the nuclide is a dissolved species in water.