The helium loop of the IVV-2M reactor plant

Follow-up development work on fuel elements for fast gas-cooled reactors is a complex task, one of the most complicated ones to face in designing any new reactor type. The most important factor determining the quality of the fuel element is fuel element reliability, which must be of a high order in order to meet safety requirements. Suffice it to say that malfunctioning of reactor fuel elements must, for reasons of radiation safety, be kept to 0.1% of the total number in service at any one time. Strivings to achieve a high level of reliability prompt the need for comprehensive effects at improved design of the fuel elements for fast-neutron gas-cooled reactors in reactor loops. Reactor tests are the sole means of fostering improved design of fuel elements under real service conditions both with respect to coolant parameters and neutron physics characteristics. Of great importance in tests of fuel elements is the possibility of designing a coolant composition adequate for reactor environments, and that is particularly crucial in the case of fuel elements jacketed in a thin-walled shell and seeing service at elevated temperatures while subjected to quite substantial loads from pressure drops