PROGRESS OF TARGET SYSTEM OPERATION AT THE PULSED SPALLATION NEUTRON SOURCE IN J-PARC

摘要

At the Japan Proton Accelerator Research Complex (J-PARC), we have operated the mercury target with injecting gas micro-bubbles to mitigate the cavitation damages took place at the target vessel front with 3 GeV proton beam at 25 Hz. For the 1 MW equivalent proton pulse injection, the displacement velocity of the target vessel reduced to about one third by the gas micro-bubbles injection. After the 2050 MWh irradiation with an average power of 275 kW, we inspected the inner surface of the target front and observed no significant cavitation damages. For the target vessel replacement operations, we obtained promising result in suppressing uncontrollable tritium release from the target vessel down to about 6 % of that released through the first replacement with an assist of the off-gas process system.