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Maeda, Yukimoto*; *; *; *; *; *; *
PNC TN941 85-61, 50 Pages, 1985/03
Experimental Fast Reactor "JOYO" started its operation at 100MWt after finishing the core conversion work. On December 2, 1983, JOYO finished the second duty cycle at 100Mwt, and subsequently the 4th annual inspection was begun. Since the maintenance work in the underfloor such as inspection of overflow EMP is conducted near the primary pipings and equipments, the radiation exposure by the maintenance is problem for the man rem saving. As the maintenance work in the underfloor is necessary to keep integrity of equipments, it is important to obtain the dose rate distribution on the surface of the primary cooling system pipings for decreacing the radiation exposure. This report describes the results of measurement of the dose rate on the surface of the primary cooling system pipings with sodium drained which was conducted before starting the 4th annual inspection. The measurement was conducted the first time after starting the Mark-II operation, and we would like to use the obtained data for designing the future reactors by continueing the measurement. The results are as follows: (1)The dose rate was increased all over and the trend of increasing was almost same as last time. (2)The increase of dose rate on the surface of the large components such as primary main pumps and intermediate heat exchangers (IHX) was remarkably high, especially on the surface of IHX(B). (3)The dominant nuclides were 
Mn and 
Co, and the contribution of 
Na was small.
*; Maeda, Yukimoto*; *; *; *; *
PNC TN941 85-12, 32 Pages, 1985/02
As a part of the Fourth annual inspection of Joyo, local leak rate tests of the reactor containment vessel were carried out in order to confirm its structural integrity from December, 1983 to April, 1984. Both measured total leak rates were as follows and satisfied the allowable value of 1.14%/day. (1)Total leak rate of the B type such as cable penetrations: 4.699
10
%/day. (2)Total leak rate of the C type test for isolation valves: 7.10610 %/day. In this report the test procedure and results were presented.
Nakano, Makoto*; *; *; *; *; *; *
PNC TN942 83-04, 46 Pages, 1983/06
This report deals with the incidents recorded during the period from April 1981 to March 1982. During this period JOYO was operated 4th to 6th normal operation cycle at rated power 75MW. From January 1982, Mark two project was started. 270 incidents or troubles were requested to repair. 0f these 12% were associated with the secondary sodium cooling system and 11% with the service building air conditioning system. From the analysis of these incidents, the frequency of incidents involving instrument is highest. Valves and control panels are also high.
*; *; *; *; *; *; *
PNC TN941 83-27VOL2, 456 Pages, 1983/02
PNC-TN941-83-27VOL2.pdf:20.9MB
None
*; *; *; *; *; *; *
PNC TN941 83-27VOL1, 827 Pages, 1983/02
PNC-TN941-83-27VOL1.pdf:25.12MB
In the Experimental Fast Reactor "Joyo", Core Conversion from the Breeding Core (MK-I Core) to the Irradiation Core (MK-II Core) was begun in January 1982. Core Conversion required the refueling of 290 core elements, reconstruction of the control rod drive mechanism, and change-out of both the upper guide tube and lower guide tube of the control rods. The schedule for these activities was planned carefully to achieve 100MWt power in March 1983. Joyo achieved MK-II core initial criticality on November 22, 1982, on schedule and immediately began core characterzation. As the result of the Core Conversion activities, we handled many core elements, twice as many as before this core conversion, and in so doing obtained many kinds of experience and data for maintenance and operation of the refueling system. This report describes the considerable pre-conversion activities and planning, and the accomplishments and results of these Core Conversion activities.
*; *; *; Inoue, Teruji*; *; *; *
PNC TN941 82-117, 950 Pages, 1982/05
The reactor power of the Experimental Fast Reactor Joyo was raised to 50 MW in July, 1978 and then to 75 MW in July, 1979. This report discribes the temperature distributions of the rotating plugs of Joyo measured from April, 1978 through December, 1981. The following results were obtained. (1)The overall temperature distributions of the large rotating plug the samll rotating plug, and the upper-core-structure have a tendency to become higher in this order and become steady state within about a week. (2)The temperature distributions of the rotating plugs have no tendency to change periodically within either a few days or longer period, and unusual temperature distributions due to imbalanced sodium vapor deposition have not been detected.
March 1981)Nakano, Makoto*; *; *; *; *; *; *
PNC TN942 82-02, 57 Pages, 1982/03
This reports deals with the incidents recorded during the period from April 1980 to March 1981. During this period JOYO operated the second, third and the half of forth normal operation cycles with the second annual maintenance. JOYO has 247 reported incidents and troubles in this period. 0f these 17% were associated with the secondary sodium cooling system and 16% with the service building air conditioning system. During this period the frequency of incidents involving instrument is highest and amounted to 17% of total numbers of incidents however, that of valves, detectors, control panels, piping and cabling, and belts are also high.