Safe handling experience of a tritium storage bed

In an ITER facility, about 3 kg of tritium will be stored in about 50 hydride beds. The safe design and operation of tritium storage beds will be one of the most important points for enhancing overall safety in the facility. In the Tritium Process Laboratory at the Japan Atomic Energy Agency, many tritium storage beds with zirconium–cobalt (ZrCo) and uranium (U) have been used with/without self-accountancy measures, and 20 years of safe handling experience has been accumulated. From this experience, the key issues to be considered for the safety design are the effects of tritium decay, such as decay heat transfer and 3He behavior, which can cause an increase in temperature and pressure in the tritide vessel, along with the normal protection against over-temperature, over-pressure and leaks in the metal-hydride bed. Concerning the safety operation, the key issues are the hydrogenation–dehydrogenation cycle sequence under the requirements of the storage system and the emergency action, such as rapid hydrogen recovery and loss of normal cooling function.