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; *; Moro, Satoshi; *
Nihon Genshiryoku Gakkai-Shi, 29(1), p.48 - 57, 1987/01
Times Cited Count：0 Percentile：0.02(Nuclear Science & Technology)*; *
PNC TN942 85-02, 31 Pages, 1985/03
In the case of fast breeder reactors, the in-service inspection of the reactor vessel must be conducted under such severe conditions as relatively high temperature, high radiation dose, and narrow space. Therefore, the heat- and radiation- resistant sensors are required, which also should be compact and flexible for remote handling and installing. Authors reviewed the state of the fiber scopes for the visual in-service examination, and discussed some problems about applicability to FBR conditions. This report presents the technical information obtained from the survey conducted in 1983, and the brief draft of the development plan including some remained problems about application to FBR.
*; *; *; *; *; *; *
PNC TN941 84-169, 172 Pages, 1984/12
A design study was conducted in order to establish the concept of the FBR plant eliminating the secondary sodium loop. Conditions for realization and effectivenesses for cost reduction were also studied for this plant. The main topic for understanding this plant concept was recognized as to clearify "the influence of sodium-water reaction to the reactor core", broken out in the steam generator. Discussions were mainly focussed on the reactor core, the steam generator, the containment vessel, sodium-water reaction product relief system and so on, which were supposed to be especially important for this plant concept. Following items were recognized. (1) Total image and concept of the FBR plant eliminating the secondary sodium loop. (2) Influence of the sodium-water reaction product, especially hydrogen gas, to reactor core and limit of the water-leak rate for core damage. (3) Countermeasures for reduction and elimination of these influences. (4) Concepts of the safety map for sodium-water reaction of this plant and requirements for water leak detection systems. (5) Necessity of the duplex tube type steam generator from the view point of property protection. (6) Reduction effect for the amount of materials and construction cost by adopting this concept of plant. A overall process for design study was experienced throuqh the activities of this work.
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PNC TN241 84-01, 49 Pages, 1984/01
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PNC TN941 82-217, 48 Pages, 1982/10
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Muramatsu, Toshiharu; *; *; *; *; *
PNC TN941 82-176, 90 Pages, 1982/08
The eddy current type flow meters were installed above the center of the core in "JOYO", in order to study their feasibiliey under high temp and high energy neutron flux condition. The characteristics of flowmeter placed at the center are as followings, (1)The unbalance signal of flow signal drifted-40%, compared with result at 4th oyde operation of 75MW power. (2)The lineality of flow signal at sensor 1 VS. main flow was obtained as
5% of full scall in each test case. (3)The lineality of temperature dependency of flow signal. at 1 sensor was obtained as 4% of 600
C full scale. (4)The lineality of temperature signal at sensor 1 VS. Thermocouple (TC-1) was obtained as 1% of full scale 600C on each test cycle. (5)Change of each coil resistance was very in significant at neutron flux level of about 4.06
10
n/cm
for 130days.
*; *; Sasaki, Makoto; *
PNC TN941 81-239, 62 Pages, 1981/12
This report describes the presumption about the causing mechanism of the power Coefficient Anomaly in JOYO, which occurred in 75 MW Power Ascension Test, summer 1979. After the previous report, the new information about the results of the post irradiation examination and the analyses about JOYO power coefficient could be obtained. The causing mechanism of the anomaly could be presumed from these information as follows. [Step 1]-50 MW Power Operation Period- The fuel burn-up reached about ten thousand MWD/ton at the end of 50 MW duty 2nd cycle, and the produced fission gas was almost retained in the fuel pellets. [Step 2]-Fission Gas Release during Initial Power Ascension from 50 MW to 75 MW- On the occasion of the initial power ascension from 50 MW to 75 MW, the fission gas release began suddenly at the power level of some above 50 MW. [Step 3]-Rising of Fuel Pellet Temperature and Appearance of Pellet Crack due to Fission Gas Release- The fission gas release reduced the gap conductance and caused the rising of fuel pellet temperature and appearance of pellet crack. These phenomina induced the fuel stack length to elongate abruptly. [Step 4]-Abnormal Behavior of Power Coefficient- The fuel temperature rising and the fuel stack length elongation induced the fuel expansion reactivity effect and Doppler reactivity effect to enlarge, and caused the anomaly behavior of power coefficient. [Step 5]-Power Coefficient Changing and Reactivity Loss of 40 cent- After the initial 75 MW, the fuel stack length didn't respond nomaly to the reactor power change by some reason. Therefore, the magnitude of power coefficient became smaller and the power level dependency changed after 75 MW. At the shut down of reactor, the core average stack length elongated a few mm and the reactivity of about 40 cent was lost from the core after the power coefficient anomaly. As mentioned above, it is presumed that the causing mechanism of the power coefficient anomaly in JOYO was the ...
*; ; ; Yamamoto, Hisashi*
PNC TN941 81-102, 117 Pages, 1981/05
This report describes the Power Coefficient Anomaly in JOYO, which occurred in 75MW Power Ascension Test, Summer 1979. The substance of this anomaly was the non-reproducible power coefficient during the initial power-up from 50MWt to 75MWt and the permanent reactivity loss of -40 cent in isothermal condition. And this anomaly was accompanied the time-dependent changes of power coefficient and the recovery of the reactivity which were never obserbed before. The cause of this anomaly has not been identified perfectly yet, but the investigation about the cause has reached the stage to focus two candidates as the cause of the anomaly (1. the elongation of ruel stuck 2.the inclination outward of fuel subassembies), as the results of various approaches to the Anomaly, that is, analyses, plant experiments and fuel post-irradiation tests. Now, the effort of accumulation and investigation of data and analyses is continued in JOYO.
*; *
PNC TN941 80-147, 28 Pages, 1980/08
The drift of the output signal from sheathed chromel/alumel thermocouples is believed to result from corrosion of the thermoelectric conductors by diffused air. The extent of the drift depends on the maximum temperature and the period of time that the thermocouple is exposed to the elevated temperature. During use as temperature sensors, it is inevitable that temperature gradients exist along the length of the thermocouple itself. These gradients results in nonuniform thermoelectric properties of the conductors which also affects their output. The drift observed in the sheathed chromel/alumel thermocouple which are used in the JOYO reactor has previously been reported. Additional tests and investigations were conducted to confirm the above phenomenon and to measure their effects. The results of these investigations are summarized as follows: (1)The drift of the thermocouple which is mounted in the reactor outlet pipeline is larger than the drift of the thermocouple which is mounted in the reactor inlet line. (2)Drift of the thermocouple head portion, which is exposed to high temperature, is larger than the drift of the thermocouple end portion which is exposed to room temperature.
Setoguchi, Keiichi; ; *
PNC/ENEA Information Exchange Meeting on Maintenance and ISI for FBRS, ,
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