The HANARO reactor constructed from Jan. 1985 to April 1995, and a major utilization system, the Cold Neutron Research Facility was completed Nov. 2010. The cold neutron research facility consists of a Cold Neutron Source, a process system, a neutron guide and a Spectrometer. A moderator is utilized to transform thermal neutrons into cold neutrons. A moderator cell accommodates the moderator. The inner assembly contains an aluminum moderator cell connected to a stainless steel heat exchanger by a bi-metallic transition joint. An In-Pool Assembly is welded to this inner assembly and a double flexible pipe, and a vacuum chamber is inserted. After HANARO reactor shutdown, the in-pool assembly was installed at a cold neutron hole in the reactor pool. We confirmed a precise installation by using an underwater TV camera for a nuclear reactor inspection. In-pool assembly connected to double flexible pipe each system in the Cold Neutron Research Facility. After cold neutron research facility operated, the reliability of vacuum system, helium refrigerator system, gas blanket system and hydrogen system for maintenance was confirmed.

The Cold Neutron Research Facility(CNRF) is being built to produce a cold neutron which has peculiar physical property. In-Pool Assembly(IPA) was manufactured in a domestic factory, which is composed of moderator cell, heat exchanger, vacuum chamber, joint flange assembly and bracket etc. We had difficulties with the mechanical fabrication process due to the thin moderator cell. The special flange for the double flexible piping was developed. The tests of moderator cell, heat exchanger, vacuum chamber, double flexible pipe and IPA include the pressure test, normal temperature leak test and low temperature leak test. The moderator cell and heat exchanger were tested in the severe environmental condition and the burst tests of moderator cell were carried out. Above all, the bursting point took place at the area of the 0.01mm thinner place. It shows that the severe environmental test affects the bursting strength. The double flexible pipe welding at the IPA top plate was related with the arrangement of moderator cell in the vacuum chamber. Therefore the connecting welding of the double flexible pipe linked to sequent of the vacuum piping, helium piping and hydrogen piping. The fabrication, test and assembling of cryogenic in radiation zone were developed.