Design of the GAGG scintillator for high active liquid waste

Sekine, Megumi; Matsuki, Takuya ; Suzuki, Satoshi*; Yasuda, Takeshi; Tsutagi, Koichi ; Nakamura, Hironobu ; Tomikawa, Hirofumi

The IAEA has proposed in its long-term R&D plan, the development of technology to enable real time flow measurement of nuclear material as a part of an advanced approach to effective and efficient safeguards for reprocessing facilities. To address this, JAEA has designed and developed a neutron coincidence based nondestructive assay system to monitor Pu directly in solutions which is after purification process. A new detector to enable monitoring of Pu in solutions with numerous FPs has been developed as a joint research program with U.S. DOE at the High Active Liquid Waste (HALW) Storage Facility in Tokai Reprocessing Plant. In a previous study, there is no report about direct ray measurement from high radioactive liquid waste (HALW) tank. In this study, in order to investigate the signal applicable to Pu monitoring, JAEA developed a small ray detector which uses Ce GdAlGaO (Ce GAGG) scintillator. The new detector is directory usable inside of the concrete cell shielding HAWL tank, measureable till 12 MeV energy range to detect delayed rays, and available to insert through 6 cm diameter penetration pipe. This paper presents the development of radiation source file, design of GAGG scintillator, and results of ray measurement at the inside of the concrete cell.