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Shirai, Nobutoshi; Taguchi, Katsuya; Iitsuka, Shoji; ; *; Sudo, Toshiyuki
JNC TN8410 99-055, 69 Pages, 1999/09
As a part of the safety confirmation work of Tokai Reprocessing Plant, an assessment of the basic data for criticality safety and shielding design has already been reported. In that report, two plutonium solution storage cells were evaluated to be safe enough from a viewpoint of multiple unit criticality safety. In this report, additionai evaluation of multiple unit criticality safety was made for the main plant and the UO
storage which were designed in 1960's and constructed in 1970's. The evaluated cells and rooms are enriched uranium dissolution cell, adjustment and feeding cell, two second extraction cycle cells, third uranium cycle cell, uranium concentration and denitration rooms, third plutonium cycle cell, plutonium concentration cell, two plutonium solution storage cells, rework cell, and UO storage room. As a result, it was confirmed that these cells and rooms were safe enough from a viewpoint of multiple unit criticality safety.
*; Iitsuka, Shoji; *
PNC TN9410 89-137, 66 Pages, 1989/08
Oxide dispersion strengthened ferritic steel (ODS) is expected to be applied for the long life core materials in large scale FBR, because of good swelling resistance and high creep strength. In this study, creep-rupture, low-cycle fatigue and physical properties tests were performed on MA957 and MA956 in air. Furthermore, various basic materials properties were evaluated. Creep-rupture tests were conducted up to 10,000 hours at 600-800
C. Low-cycle fatigue tests were conducted at 550-750C under strain control mode with full-reversed triangular waves, at the strain rate of 0.1 %/sec and the total strain range of 0.5-1.2 %. Creep-rupture strength of MA957 was higher than that of 20% cold-worked modified SUS316 SS at long time. But the specimen picked up from transverse angle against drawing direction showed the significant decrease in creep-rupture strength. MA956 had lower creep-rupture strength than MA957. It was same as those of 9Cr
12Cr ferritic steels. Creep-rupture elongation was few percents expect for that of MA956 at low-temperature range (
650C). Fatigue life of MA957 was a little lower than that of SUS316 SS at strain range below 1.0%. Under high strain condition, cyclic hardening was observed. Physical properties of MA957 were similar to those of martensite SUS410. These results will be reflected to development of oxide dispersion strengthened ferritic steel.
Kuroha, Mitsuo; Takeda, Kunio; Iitsuka, Shoji; Sasaki, Shuichi; Okada, Toshio; Isozaki, Mikio; Daigo, Yoshimichi; Sato, Minoru
PNC TN941 81-49, 204 Pages, 1981/05
PNC type in-sodium hydrogen meters have been developed as leak detectors for LMFBR MONJU steam generators. In order to confirm the long-term reliability and the durability of the meters, the four meters were installed in three sodium loops at the O-arai Engineering Center, and they had been tested over a long time in flowing sodium. A period of the test was from oct. 1977 to Feb. 1980. They are called type II. The dynamic chamber of the vacuum system can separate from the static one, and be also connected with it using one flexible tube. Important findings from the test are; (1) The operating time of two meters exceeded 10,000 hours, and the total of all meters was about 35,000 hours. No trouble had been experienced in the sodium systems and the nickel membranes of them during the period, which had the good durability. Air leaks, however, occured three times in the two vacuum systems. (2) Any secular changes had hardly happened in the permeability of hydrogen through the nickel membrane and the relationship between ion pump current and hydrogen pressure. (3) The pumping speeds had decreased with increasing the amount of absorbed hydrogen. The decreasing rates differed among four ion pumps, and those of two pumps were considerably large at the beginning of absorbing hydrogen. (4) The calibration curves, which describe the relationship between hydrogen concentration in sodium and ion pump current, had changed with time. The largest cause was the decrement of the pumping speeds. (5) The UHV gauges were superior to the ion pumps from the point of the signal-to-noise ratio as the hydrogen sensor.
