A Challenge for a High-Resolution Ag-In-Cd Decoupler in Intensified Short-Pulsed Neutron Source

Abstract

A sharp pulsed-neutron beam, which has narrow width and large attenuation, will enhance ability to separate peak position diffracted from crystal structure in time-of-flight measurement method. Traditional technique to satisfy the request above is to use Boron for decoupling higher cut-off energy. Disadvantage, however, will be an excess formation of He bubbles and large heat deposition in the materials as a result of (n,α) reaction, particularly in a MW class of neutron source. Alternative is to use a material combination of Ag-In-Cd, which has different energies for resonance absorption and often used in the control rod of pressurized water reactors with cladding stainless steel. For application of this material to pulsed-neutron source a challenge is to make sandwiches structure with Al alloy because a moderator is made of this material from points of views of heat removing. Technically hot isostatic pressing was a choice and devoted to realize a bonding strength through R&Ds. Final product was set up to MLF /J-PARC and a successful resolution was observed in a powder diffractometer.

Current Status of the High Intensity Pulsed Spallation Neutron Source at J-PARC

“…For heat removal and corrosion protection, the Ag-In-Cd plate had to be bonded to the Al alloy (A5083) that is the structural material of the moderator and reflector. We adopted a hot isostatic pressing (HIP) method [19,20] and succeeded in obtaining the required bonding. The thickness of the Ag-In-Cd layer was determined to be 3 mm for it to survive longer than the estimated lifetime of the aluminum alloy for 6 MWy of irradiation time in the high-radiation environment of the present target-moderato-reflector system.…”

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex I: Pulsed Spallation Neutron Source

“…In view of heat removal and corrosion protection, however, there was the issue that the Ag-In-Cd plate has to be bonded to the Al alloy (A5083), the structural material of a moderator and reflector. We succeeded to implement Ag-In-Cd alloy into the moderator-reflector as a decoupler by adopting HIP (Hot Isostatic Pressing) method [49,51,52]. In order to validate neutronic performance of the Ag-In-Cd decoupler, the pulse shape was observed in the rise and tail part of the Bragg peaks.…”

“…adopting HIP (Hot Isostatic Pressing) method [49,51,52]. In order to validate neutronic performance of the Ag-In-Cd decoupler, the pulse shape was observed in the rise and tail part of the Bragg peaks.…”