Installation and performance tests of KUR cold neutron source, 1

The first reactor cold neutron source in Japan installed into the graphite thermal column of KUR is described with its fundamental structures and the safety design aspects. Liquid deuterium and hydrogen mixture of about 4 litres was decided as the cold moderator from the optimized design in our case. The cold moderator chamber was made of thin aluminium alloy, and a helium-neon safety blanket is also provided on the vacuum insulation container. These important portions with the hydrogen condenser and liquid transfer tubes were manufactured as a completely unified machine with the highest quality of welding. The principle so called 2-out-of-3 system with a high reliability is employed in the important instrumentations. A series of condensation and steady operation tests, including the later start-up of cooling under full power reactor operations, on liquid hydrogen moderator showed quite satisfactory performances of the present cold source. The deuterization and the neutron guide tubes preparations are now under progress. (author)