An efficient and safe blanket concept is proposed in which the periodically recirculative clad balls are used for tritium production. Tritium will be produced inside the blanket and recovered with the equipment outside the blanket at different temperatures.

If clad (depleted) uranium balls are used as a neutron multiplication medium, when coolant pressure (or flow) reduces to the minimum value predicted for safety, all balls automatically drop into passive cooling tanks to keep whole system in a safe condition. The system performance in different situations is given.