Development of a combined neutron resonance analysis technique as a nondestructive assay for fissile material quantification

Year
2024
Author(s)
Fabiana Rossi - Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN), Japan Atomic Energy Agency (JAEA), Ibaraki, Japan
Jaehong Lee - Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN), Japan Atomic Energy Agency (JAEA), Ibaraki, Japan
Yu Kodama - Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN), Japan Atomic Energy Agency (JAEA), Ibaraki, Japan
Kota Hironaka - Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN), Japan Atomic Energy Agency (JAEA), Ibaraki, Japan
Koizumi Mitsuo - Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN), Japan Atomic Energy Agency (JAEA), Ibaraki, Japan
Junichi Hori - Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan
Kazushi Terada - Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan
Tadafumi Sano - Atomic Energy Research Institute, Kindai University, Osaka, Japan
Abstract

A variety of non-destructive assay (NDA) techniques are employed to verify nuclear materials. However, one of the challenges of NDA is the measurement of highly radioactive materials. Since 2015, the Japan Atomic Energy Agency has been engaged in the development of active nondestructive assay techniques to address some of the current challenges in nuclear safeguards. One of the proposed techniques is the integrated neutron resonance analysis system. Neutrons are generated by a pulsed neutron source, slowed down in the moderator, and collimated to reach the sample, where various neutron-induced reactions take place. Plastic scintillators are employed to quantify the collected gamma rays and fission neutrons at the sample location; GS20 is utilized to collect the transmitted neutrons downstream of the source-sample beamline. A preliminary measurement campaign was conducted using a natural uranium sample, wherein the viability to identify fissile materials was demonstrated. In order to enhance n/g discrimination, novel pulseshape discrimination scintillators were introduced and tested in 2023. The preliminary results indicate the presence of distinct fission resonance peaks of increasing intensity with varying thicknesses of natural uranium samples. Currently, an assembly of multiple scintillators is being investigated to enhance the signal-to-noise ratio. The new setup will be tested starting in early 2024. This paper will describe in detail the project development and the experimental setup.