VHTR cooling system performance verified

The passive cooling system of the proposed Very High Temperature Reactor (VHTR) has successfully passed simulation verification tests, the Korea Atomic Energy Research Institute has announced. In addition to producing electricity, the advanced reactor design could also be used to produce hydrogen.

The passive cooling system of the proposed Very High Temperature Reactor (VHTR) has successfully passed simulation verification tests, the Korea Atomic Energy Research Institute (KAERI) has announced. In addition to producing electricity, the advanced reactor design could also be used to produce hydrogen.

KAERI has submitted a VHTR design to the Generation IV International Forum with a view to hydrogen production from it. This is envisaged as 300 MWt modules operating at above 900ºC, each producing about 30,000 tonnes of hydrogen per year.

The NACEF test facility (Image: KAERI)

The VHTR - which is fuelled with ceramic-coated uranium - is designed to automatically cool down by circulating air using helium as a coolant and graphite as a moderator.

Should the temperature within the VHTR exceed 950ºC - such as in the event of an accident or loss of external power - air is allowed into the reactor vessel and then to the Reactor Cavity Cooling System (RCCS). The heated air rises and exits through the reactor's natural circulation riser (chimney), drawing in cold air and gradually removing the residual heat from the reactor.

KAERI announced yesterday that its researchers had carried out a passive safety simulation verification test on the VHTR's RCCS. They used the Natural Cooling Experimental Facility (NACEF) - a one-quarter scale model of the RCCS - to test the natural cooling device. The NACEF can simulate accident conditions by creating a high-temperature environment using electrical heat, not actual nuclear fuel.

The tests using the NACEF showed that the cooling system worked successfully.

KAERI said it will continue to cooperate with the Argonne National Laboratory and Wisconsin State University to carry out research on the development of passive safety devices for the RCCS.

A demonstration VHTR units is expected to be constructed by 2020, with commercialization envisaged by 2025.

Researched and written
by World Nuclear News