Self-Developed Test Platform for Evaluation of Operation Conditions of Neutron Moderator

A novel test platform was developed for evaluation of the cryogenic,vacuum and sealing conditions of the neutron moderator and hydrogen moderator for China Spallation Neutron Source.The self-developed test platform comprised the liquid-nitrogen supply,heating of gas unit,flow-rate controller,monitoring of temperature subunit,and pressure alarm subunit. The red-copper resistive heaters turn liquid nitrogen into cold gas(80~100 K); and the cryogenic pipelines were thermally insulated. The test platform was used to evaluate the coupled/decoupled posioned hydrogen moderators. The results show that the test platform meets all the stringent design requirements. For example,it is capable of providing cryogenic nitrogen-gas at a flow-rate up to 500 L/min with a tolerance of 10% and a gas temperature control precision of 5±K. We suggest that the test platform be of some technological interest in testing large-sized vacuum and/or cryogenic equipment.