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JAEA Reports

Evaluation of the performance of the shields in the EPMAs used for radioactive samples

Matsui, Hiroki; Suzuki, Miho; Obata, Hiroki; Kanazawa, Hiroyuki

JAEA-Technology 2014-017, 57 Pages, 2014/06

JAEA-Technology-2014-017.pdf:20.43MB

The Reactor Fuel Examination Facility in JAEA has been used for Post Irradiation Examinations to verify the reliability and safety of the nuclear fuels irradiated in commercial reactors. EPMA (Electron Probe Micro Analyzer) has been utilized for the qualitative analysis of the fission product in the fuel pellet and the detailed observation of the oxide layers formed at the inner and outer surfaces of fuel cladding. Commercial EPMAs were remodeled so that the EPMAs can be applied for radioactive samples. Several shields was set in the EPMA to avoid the $$gamma$$-rays which radiate from a radioactive sample to the proportional counter in the EPMA. It is important to calculate this shielding performance adequately to maintain the precision of analysis. This report describes the results of re-evaluation of the performance of the shields in the EPMAs in the RFEF by using the Particle and Heavy Ion Transport Code System and the examination results of $$gamma$$-ray effect to the X-ray spectrum data by using a radioactive sample.

JAEA Reports

Development of remote controlled electron probe micro analyzer with crystal orientation analyzer

Honda, Junichi; Matsui, Hiroki; Harada, Akio; Obata, Hiroki; Tomita, Takeshi

JAEA-Technology 2012-022, 35 Pages, 2012/07

JAEA-Technology-2012-022.pdf:3.58MB

The advanced utilization of Light Water Reactor (LWR) fuel is progressed in Japan to save the power generating cost and the volume of nuclear wastes. The electric power companies have been continued the approach to extend the burnup and to rise up the thermal power of the commercial fuel. The government should be accumulating the detailed information of the newest technologies to make the regulations and guidelines for the safety of the advanced nuclear fuels. The remote controlled Electron Prove Micro Analyzer attached with crystal orientation analyzer (EPMA) has been developed in Japan Atomic Energy Agency (JAEA) to evaluate the fuel behavior effected by the cladding microstructure under the accident condition. The device was modified to the airtight and earthquake resistant structure for the examination of high radioactive elements. This paper describes the specification of EPMA and the test results of the cold mock-up to confirm their performances and reliabilities.

JAEA Reports

Development of remote controlled ion milling device

Honda, Junichi; Matsui, Hiroki; Harada, Akio; Obata, Hiroki; Tomita, Takeshi

JAEA-Technology 2012-021, 17 Pages, 2012/07

JAEA-Technology-2012-021.pdf:4.17MB

The advanced utilization of Light Water Reactor (LWR) fuel is progressed in Japan to save the power generating cost and the volume of nuclear wastes. The electric power companies have been continued the approach to extend the burnup and to rise up the thermal power of the commercial fuel. The government should be accumulating the detailed information of the newest technologies to make the regulations and guidelines for the safety of the advanced nuclear fuels. The ion milling for post irradiation examination has been developed in Japan Atomic Energy Agency (JAEA) to investigate cladding microstructure. This device has been modified to operate the high radioactive elements remotely and have the performance of earthquake resistant. This paper describes the specification of the device which were specialized for post irradiation examination and the test results of the cold mock-up to confirm their performances and reliabilities.

Oral presentation

Mechanical properties of W alloys and pure Ta irradiated at SINQ target 4

Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Suzuki, Kazuhiro; Endo, Shinya; Obata, Hiroki; Kurishita, Hiroaki*; Watanabe, Ryuzo*; Kawai, Masayoshi*; Yong, D.*

no journal, , 

no abstracts in English

Oral presentation

Determination of hydrogen concentration in Zircaloy cladding using hot vacuum extraction method with two-step heating

Obata, Hiroki; Toyokawa, Takuya; Tomita, Takeshi; Kimura, Yasuhiko

no journal, , 

Hydrogen absorption to the fuel cladding is increase on the high burn-up fuel. The concentration of absorbed hydrogen causes the cladding embrittlement which might become the origination of fractures of the cladding. Therefore, it's important to measure the hydrogen volume in the cladding to estimate the safety margin of the irradiated cladding. In the previous method of hot vacuum extraction, the hydrogen is released and measured as the melting condition of the cladding. It cannot be evaluated the hydrogen volume only in the cladding metal phase. The hydrogen absorption in the cladding metal phase is strongly-correlated the cladding embrittlement. The two-step heating method has the benefit to measure the hydrogen in metal phase and oxide layer separately. The measuring method including the extraction temperature condition using unirradiated cladding will be reported.

Oral presentation

Detailed inspection of samples taken from un-irradiated fuel assembly at 1F4, 1; Outline of inspected samples and inspection methods

Motooka, Takafumi; Endo, Shinya; Sonoda, Takashi; Oki, Keiichi; Uehara, Hiroyuki; Obata, Hiroki; Tsukada, Takashi

no journal, , 

no abstracts in English

Oral presentation

Detailed inspection of samples taken from un-irradiated fuel assembly at 1F4, 2; Results of observation by microscopy and surface analysis by SEM/EPMA

Uehara, Hiroyuki; Obata, Hiroki; Endo, Shinya; Kawamata, Yutaka; Motooka, Takafumi; Tsukada, Takashi

no journal, , 

no abstracts in English

Oral presentation

Technique of hydrogen concentration measurement in fuel cladding

Obata, Hiroki

no journal, , 

no abstracts in English

Oral presentation

Determination of hydrogen concentration in Zircaloy cladding using hot vacuum extraction method with two-step heating

Obata, Hiroki; Toyokawa, Takuya; Tomita, Takeshi; Kimura, Yasuhiko

no journal, , 

The amount of hydrogen absorbed to the fuel cladding increases by extended burnup fuel. The absorbed hydrogen that exceed solid solubility limit precipitates as the hydride phase. The high concentration of hydride causes the fuel cladding embrittlement which might become the origination of fractures of the cladding. Therefore, it is important to measure the hydrogen content in the cladding to estimate the safety margin of the irradiated cladding. Hydrogen is absorbed not only in the cladding metal phase, but in the oxide layer. To evaluate the embrittlement of the cladding, it is necessary to measure the hydrogen content in the cladding metal phase and oxide layer separately. Therefore, the two-step heating method can measure the amount of hydrogen in the metal phase and the oxide layer separately. This paper shows the technical review of measuring method including the technique for the determination of extraction temperature.

Oral presentation

Detailed inspection of samples taken from un-irradiated fuel assembly in 1F4, 3; Results of cross sectional observation by optical microscope and SEM/EPMA

Endo, Shinya; Motooka, Takafumi; Uehara, Hiroyuki; Obata, Hiroki; Kawamata, Yutaka; Ueno, Fumiyoshi

no journal, , 

no abstracts in English

Oral presentation

Characterization of fuel debris (27'A), 9; Microhardness of simulated fuel debris and TMI-2 debris

Takano, Masahide; Onozawa, Atsushi; Suzuki, Miho; Obata, Hiroki

no journal, , 

no abstracts in English

Oral presentation

The Results obtained from the 20 years of "Monju" plant data, 11; The Shaft sealing mechanism of primary sodium pump

Hashidate, Ryuta; Morioka, Tatsuya; Sawazaki, Hiromasa; Shiotani, Hiroki; Obata, Ikuhito; Uekura, Ryoichi

no journal, , 

We have been evaluating mainly the data acquired by the central computer so far, but we focused on evaluation using preservation data from this time. In this report, we report on the results of examination of the shaft sealing mechanism which constitutes the boundary of the cover gas including sodium vapor from the viewpoint of seal gas effect considered in the design stage for sodium vapor and sealability of the cover gas boundary by using the Monju plant data and conservation data for 20 years.

Oral presentation

Revisiting the TMI-2 core melt specimens to verify the simulated corium for Fukushima Daiichi NPS

Takano, Masahide; Onozawa, Atsushi; Suzuki, Miho; Obata, Hiroki

no journal, , 

For the decommissioning of damaged cores of Fukushima Daiichi NPS, the retrieval operation of solidified core melt (corium) and its safe management are essential tasks. To understand characteristics of corium specific to the 1F cores, we have prepared and analyzed various types of simulated corium specimens in laboratory scale. To verify the effect of cooling condition found on the simulated corium, we revisit the actual corium specimens collected from the TMI-2 accident core, which have been stored at the Reactor Fuel Examination Facility (RFEF) in JAEA Tokai since 1991. Comparing the phases and microstructure, rapid-cooled specimens have dense microstructure and consist of single phase of cubic structure. On the other hand, the slow-cooled specimens consist of U-rich cubic and Zr-rich tetragonal phases distributed minutely. From these observations we have confirmed the similar dependence of microstructure and mechanical property on the cooling condition.

Oral presentation

Behavior of high-burnup advanced fuels under reactivity-initiated accident (RIA) and loss-of-coolant accident (LOCA), 6; High temperature oxidation behavior of high-burnup advanced cladding tubes

Kakiuchi, Kazuo; Narukawa, Takafumi; Obata, Hiroki; Amaya, Masaki

no journal, , 

JAEA has conducted studies on fuel behaviors during loss-of-coolant-accidents (LOCA) using high-burnup advanced fuel cladding tubes. We report the evaluation results on the effects of the burnup extension and the change in the alloy compositions on high temperature oxidation of high-burnup advanced fuel cladding.

Oral presentation

Decontamination work in the Reactor Fuel Examination Facility

Ida, Yuma; Obata, Hiroki; Kimura, Yasuhiko; Onozawa, Atsushi

no journal, , 

15 (Records 1-15 displayed on this page)
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