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Volume 22, Issue 2
Displaying 1-10 of 10 articles from this issue
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Kiyomi ISHIJIMA1985 Volume 22 Issue 2 Pages 81-92
Published: February 25, 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe transient cladding deformation measurement tests have been performed under reac-tivity initiated accident (RIA) conditions in the Nuclear Safety Research Reactor (NSRR).
A single PWR type fuel rod which was instrumented with strain gage was contained within a capsule filled with water at ambient temperature and atmospheric pressure, and heated up by pulsing operation of the NSRR simulating an RIA. Transient diametral deformation of the cladding tube due to Pellet-Cladding Mechanical Interaction (PCMI) was successfully measured using strain gage. It was revealed through the experiments that strain gage de-signed for the use in steel could be applied for the measurement of transient PCMI behavior of zircaloy cladding tube if appropriate correction on temperature compensation of the strain gage was made. Data obtained by the strain gage are quite valuable for the verification of the fuel rod deformation model in the fuel behavior analysis code. Preliminary analysis showed that pellet deformation model of GAPCON-THERMAL-1 code gave good prediction on the fuel rod deformation under an RIA transient.View full abstractDownload PDF (800K) -
Tsutomu OKUBO, Yoshio MURAO1985 Volume 22 Issue 2 Pages 93-108
Published: February 25, 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe effects of the ECC water injection rate on reflooding behavior during a PWR-LOCA have been investigated using the experimental data from a large scale reflood test facility.
As a general result, the higher ECC water injection rate was found to result in the higher core flooding rate, and hence, the better core cooling. However, when the LPCI injection rate was higher than a certain value, which was enough to keep the downcomer almost filled, the core flooding rate was found to become an almost identical value being regardless of the LPCI injection rate. Also found was the effect of the Acc injection rate and duration in-fluenced the core cooling behavior through the whole transient including the LPCI period. These phenomena have been analyzed and clarified quantitatively in this paper. It was also found that the Acc injection rate and duration effects on reflooding behavior observed in the large scale facility were almost the same as those already observed in the small scale facility.View full abstractDownload PDF (1059K) -
Shun-ichi TANAKA, Nobuo SASAMOTO1985 Volume 22 Issue 2 Pages 109-119
Published: February 25, 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSCorrective factors for thermoluminescent dosimeters to obtain the γ-ray dose in materials are examined systematically based on a general cavity ionization theory, and an experimental method; interpolation method, is presented for measuring the γ-ray absorbed dose in materials using thermoluminescent dosimeters with different atomic numbers. A characteristic feature of the method is to measure the γ-ray absorbed dose in materials without any γ-ray spectrum information. In order to examine the feasibility, the absorbed doses are measured in iron, lead and polyethylene media with a 60Co γ-ray source, and compared with a transport cal-culations whose accuracy is already verified. It is shown that the γ-ray absorbed doses meas-ured using the present method agree with the calculated ones within ±5 to ±10%.View full abstractDownload PDF (706K) -
Toshimasa TOMODA, Shinji FUKAKUSA, Shinichi YAMASHITA, Kazuo AKITA1985 Volume 22 Issue 2 Pages 120-128
Published: February 25, 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSIn order to improve the well-known short operational life time of BF3 counters, three potential adsorbents for impurity gases (graphite, activated charcoal and a zirconium-aluminum mixture) were introduced into BF3 counters in the form of coating on the aluminum cathode surface. Tests in γ fields revealed that a partial coating of activated charcoal provides the best result. The improvement of their operational life in γ fields was about three orders of magnitude in terms of tolerable exposure.
Many counters with a partial coating of activated charcoal were further tested from the following viewpoints : background noise, vibration and shock, γ pulse discrimination, opera-tional life in a neutron field and non-operational in-reactor exposure life. The results were satisfactory for reactor control and protection usage.View full abstractDownload PDF (589K) -
Kenichi ITO, Ryo IWASAKI, Yoshihiko IWANO1985 Volume 22 Issue 2 Pages 129-138
Published: February 25, 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA finite element model is proposed to analyze in-pile fission gas release from UO2 fuel.
The model describes fission gas transfer from grain interior to grain boundaries by simul-taneous mechanisms of diffusive flow and boundary sweeping, considering the effect of irra-diation-induced resolution in grain boundaries. The onset of gas release is predicted when gas amount in grain boundaries is saturated. The grain is assumed to be spherical and is radially divided into a number of elements, in each of which the diffusion problem is approxi-mated by describing the gas concentration in terms of a quadratic function. The effect of grain growth is treated by updating the nodal radii incrementally. This model is applicable to variable irradiation histories and its required computer time is acceptable for use in fuel rod performance codes.View full abstractDownload PDF (623K) -
Dimensional Change and Thermal ExpansionHideto MATSUO, Tamotsu SAITO1985 Volume 22 Issue 2 Pages 139-146
Published: February 25, 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDimensional changes and thermal expansion coefficient were measured for Pechiney nuclear grade graphite irradiated in the temperature range 220400°C up to the maximum neutron fluence 2.2×1020 n/cm2 (E>0.85 MeV) in the environment of CO2 in a commercial reactor.
Dimensional shrinkage was observed for whole samples except for those which showed a slight expansion in the early stage of irradiation. Thermal expansion coefficient was almost constant up to about 7.0×1019 n/cm2. The measured dimensional changes were compared with the predicted ones obtained from a bromination method and it was confirmed that the actual dimensional change of graphite bricks in the reactor did not exceed the predicted ones.
Dimensional changes were also discussed in relation to the change of crystallite parameters due to irradiation. Distortion of the reactor core was discussed by using the experimental results as well.View full abstractDownload PDF (479K) -
Masakazu TANASE, Mineo KATO, Shoji MOTOISHI, Katsuyuki ONOMA, Hisamich ...1985 Volume 22 Issue 2 Pages 147-152
Published: February 25, 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSEquipments were constructed for the development of tritium production technology.
Gaseous tritium in a level of 3 TBq (80 Ci) was extracted from neutron-irradiated 6Li-Al alloy by heating at 1, 073 K under vacuum and collected in an activated-uranium getter. The recovery of the tritium was 90% or more and the isotopic purity of the product was about 50%. Throughout the production experiment, no release of tritium out of the equipments to the environment was observed.View full abstractDownload PDF (402K) -
Minoru SAITO, Hirotaka FURUYA, Katsumi KOGA, Masayasu SUGISAKI1985 Volume 22 Issue 2 Pages 153-154
Published: February 25, 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSOxidation behavior of the stainless steel fuel cladding is one of the important information to clarify the oxygen balance in the fast breeder reactor fuel pin during irradiation. In our previous work(1), oxidation behavior of SUS-316 stainless steel was investigated under oxygen potentials controlled by Mo/MoO2 and NbO2/Nb2O5 oxygen buffers, and the following information was obtained : The reaction product due to oxidationwas a mixture of Cr2O3 and MnCr2O4, and the oxidation rate was controlled by the outward diffusion of Cr in stainless steel ; this diffusion process was ascribed to the grain boundary diffusion because the activation energy, calculated from the temperature dependence of the parabolic rate constant, was close to that of the grain boundary diffusion of Cr in stainless steel rather than that of the lattice diffusion(2).View full abstractDownload PDF (143K) -
Toshimichi TACHIBANA, Tsuyoshi OHMORI, Sadamu YAMANOUCHI, Toshiyuki IT ...1985 Volume 22 Issue 2 Pages 155-157
Published: February 25, 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSFor UO2 and (U, Pu)O2, many workers(1) have determined melting points by use of a filament in situ measurement. However, it is indicated that temperature measurement for this technique may be influenced by the high vapor pressure of the specimen at high temperature and the oxygen-to-metal ratio may also change during heating of the filament(2)(4). Thereafter, a thermal arrest technique has been newly developed(2) using specimen enclosed in a sealed tungsten capsule to maintain the stoichiometric composition at the melting.View full abstractDownload PDF (207K) -
Hitoshi SAKAI, Toshihide TSUJI, Keiji NAITO1985 Volume 22 Issue 2 Pages 158-161
Published: February 25, 1985
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSIt has been suggested by the present authors(1) that the oxygen concentration in water for the inhibition of the corrosion of carbon steel may correspond to the oxygen partial pressure in gas phase for the formation of the protective film on iron at 573 K. Hence it is helpful for the understanding of the corrosion rate to find its temperature dependence around 573 K in air, where the protective film is formed.View full abstractDownload PDF (273K)
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