The construction of the 280-MW MONJU, started from October 1985, a Japanese national project by Power Reactor and Nuclear Fuel Development Corporation (PNC), has been completed in April 1991 as scheduled.
Fuji Electric has supplied the fuel handling and storage system, such as the ex-vessel transfer machine and ex-vessel storage tank, and the radioactive gaseous and liquid waste treatment system. Fuji Electric have carried out the design, fabrication and construction, utilizing the experience obtained in JOYO and the results of R&D for MONJU, under the direction of PNC and Japan Atomic Power Co. responsible for administration at the site.

The function of the fuel handling and storage system of proto-type fast breeder reactor "MONJU" is to handle fuel assemblies in the station (i.e from receiving new fuel to carrying out spent fuel). Fuel assemblies are exchanged between the reactor vessel (RV) and the ex-vessel storage tank (EVST) one by one using the fuel handling machine and ex-vessel transfer machine on off-load. A spent fuel which is discharged from the RV is transferred to the EVST and stored during specified cooling period. Then a spent fuel is picked up the EVST, cleaned in the cleaning station, cannistered in the canning station, transferred to the storage rack in the fuel pond and stored till carrying out to a reprocessing plant.

The ex-vessel fuel storage tank is a stainless-steel structure of about 6-m diameter and about 10-m height to store spent fuels during radioactive decay and to store new fuels temporarily. It can store 250 fuel assemblies in 160m³ liquid sodium it contains. The design and development has secured full safety and reliability through the R&D connected with sodium technology, such as verification of fuel cooling by natural convection of sodium, settlement of the method of evaluating the seismic behavior of a large multiplex vessel containing sodium, and confirmation of the operation of nonlubricated bearings used in sodium.

The ex-vessel transfer machine carries fuels into and from the reactor vessel and transfers them between equipment. It must put fuels in and out of the sodium in the reactor vessel or ex-vessel fuel storage tank and must handle actively heat-generating spent fuels. Therefore, entrusted by Power Reactor and Nucelar Fuel Development Corporation, Fuji Electric manufactured full scale mock-up the main part of a ex-vessel transfer machine and carried out various tests for handling and cooling performance to apply the results to the actual design and fabrication.

The fuel handing system is required to handle the fuels safely and efficiently according to the specified schedule and steps. The operation and control system to meet these requirements should complete centralized supervision and automated operation that lead to the improvement of controllability and reliability.
This paper gives an outline of the system configuration and functions of the system that was designed, fabricated and installed utilizing the experience of construction and operation in the previous JOYO and FUGEN and the latest control technology.

The radioactive gaseous waste treatment system sucks gaseous waste from the fuel handling and storage system, control rod driving mechanism and primary argon gas system, and holds radioactive rare gases out of the gaseous waste for a specified time for radioactive decay to discharge them into environment without pollution. This system is composed of a waste gas compressor, a charcoal bed, tanks and piping system.

The radioactive liquid waste treatment system is designed to treat the waste liquid from the power station so that it can be reused or discharged into environment. The system consists of two systems. One for waste liquid from the equipment and drainage from the building and one for laundry waste liquid. The former system has a function to treat waste liquid in high concentration of radioactive and solid substances using a natural circulating waste liquid evaporative concentrator.

The active components maintenance facility is designed to transfer and clean the active components to be maintained, and consists of a transfer system and a sodium washing system. Mainly at the time of periodical inspection, the active components to be maintained is transferred to the maintenance area by the transfer system, is made free from adhered sodium by the sodium washing system, and is reused after inspection.

Fuji Electric with many years experience in radiation monitoring system has made a comprehensive survey of its know-how to complete the system delivered to MONJU. The system includes characteristic components such as the optical signal transmission system, the digital ratemeter and I/O control device which is available for automatic calibration of the radiation monitors in combination with radiation calibration facilities, and the cover gas sampling apparatus peculiar to the fast breeder reactor. This paper describes an outline of the radiation monitoring system and its main devices.

The ex-vessel transfer machine and the shield plug and rotating rack of the ex-vessel fuel storage tank of the fuel handling and storage system, and the evaporative concentrator of the liquid waste treatment system were fabricated in Kawasaki Factory of Fuji Electric. Those large structures were mainly made of stainless steel and required high accuracy for dimensions. This paper introduces the organization for fabrication, considerations of quality assurance and quality control, and fabrication methods to meet these requirements.

The main construction work of MONJU was started from the excavation for building foundation in October 1985, the containment vessel was prepared in April 1987, the reactor vessel was installed in October 1988, and the installation of the whole equipment was completed in April 1991, Fuji Electric made preparations for construction matching the above master schedule in consideration of construction schedule quality assurance and safety and accomplished the work within the scheduled time without personal injury as long as 2.35 million hours.