Verification of probabilistic fracture mechanics analysis code PASCAL for reactor pressure vessel

Lu, K.; Takamizawa, Hisashi; Li, Y.; Masaki, Koichi*; Takagoshi, Daiki*; Nagai, Masaki*; Nannichi, Takashi*; Murakami, Kenta*; Kanto, Yasuhiro*; Yashirodai, Kenji*; et al.

Mechanical Engineering Journal (Internet), 10(4), p.22-00484_1 - 22-00484_13, 2023/08

https://doi.org/10.1299/mej.22-00484

Measurement of the longitudinal bunch-shape distribution for a high-intensity negative hydrogen ion beam in the low-energy region

Kitamura, Ryo; Futatsukawa, Kenta*; Hayashi, Naoki; Hirano, Koichiro; Kondo, Yasuhiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Morishita, Takatoshi; Nemoto, Yasuo*; Oguri, Hidetomo

Physical Review Accelerators and Beams (Internet), 26(3), p.032802_1 - 032802_12, 2023/03

https://doi.org/10.1103/PhysRevAccelBeams.26.032802

A bunch-shape monitor (BSM) is a useful device for performing longitudinal beam tuning using the pointwise longitudinal phase distribution measured at selected points in the beam transportation. To measure the longitudinal phase distribution of a low-energy negative hydrogen (H) ion beam, highly oriented pyrolytic graphite (HOPG) was adopted for the secondary-electron-emission target to mitigate the thermal damage due to the high-intensity beam loading. The HOPG target enabled the measurement of the longitudinal phase distribution at the center of a 3-MeV H ion beam with a high peak current of about 50 mA. The longitudinal bunch width was measured using HOPG-BSM at the test stand, which was consistent with the beam simulation. The correlation measurement between the beam transverse and longitudinal planes was demonstrated using HOPG-BSM. The longitudinal Twiss and emittance measurement with the longitudinal Q-scan method was conducted using HOPG-BSM.

Evaluation of the bunch-shape monitor for the high-intensity proton beam

Kitamura, Ryo; Futatsukawa, Kenta*; Hayashi, Naoki; Hirano, Koichiro; Kondo, Yasuhiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Nemoto, Yasuo*; Morishita, Takatoshi; Oguri, Hidetomo

Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.251 - 253, 2020/09

A bunch-shape monitor (BSM) in the low-energy region is being developed in the J-PARC linac to accelerate the high-intensity proton beam with the low emittance. A highly-oriented pyrolytic graphite (HOPG) was introduced as the target of the BSM to mitigate the thermal loading. The stable measurement of the BSM was realized thanks to the HOPG target, while the tungsten target was broken by the thermal loading from the high-intensity beam. However, since the longitudinal distribution measured with the BSM using the HOPG target was wider than the expected one, the improvement of tuning parameters is necessary for the BSM. The BSM consists of an electron multiplier, a bending magnet, and a radio-frequency deflector, which should be tuned appropriately. Behavior of these components were investigated and tuned. The longitudinal distribution measured with the BSM after the tuning was consistent with the expected one.

Development of the bunch shape monitor using the carbon-nano tube wire

Kitamura, Ryo; Hayashi, Naoki; Hirano, Koichiro; Kondo, Yasuhiro; Moriya, Katsuhiro; Oguri, Hidetomo; Futatsukawa, Kenta*; Miyao, Tomoaki*; Otani, Masashi*; Kosaka, Satoshi*; et al.

Proceedings of 10th International Particle Accelerator Conference (IPAC '19) (Internet), p.2543 - 2546, 2019/06

https://doi.org/10.18429/JACoW-IPAC2019-WEPGW033

A bunch shape monitor (BSM) is one of the important instruments to measure the longitudinal phase space distribution. For example in the J-PARC linac, three BSMs using the tungsten wire are installed at the ACS section to measure the bunch shapes between the accelerating cavities. However, this conventional BSM is hard to measure the bunch shape of H beam with 3 MeV at the beam transport between the RFQ and DTL sections, because the wire is broken around the center region of the beam. The new BSM using the carbon-nano-tube (CNT) wire is being developed to be able to measure the bunch shape of the H beam with 3 MeV. The careful attention should be paid to apply the high voltage of 10 kV to the CNT wire. The several measures are taken to suppress the discharge from the wire and operate the CNT-BSM. This presentation reports the current status of the development and future prospective for the CNT-BSM.

Interlocked events of beam loss monitors at the J-PARC linac

Hayashi, Naoki; Kikuzawa, Nobuhiro; Miura, Akihiko; Futatsukawa, Kenta*; Miyao, Tomoaki*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.540 - 544, 2017/12

http://www.pasj.jp/web_publish/pasj2017/proceedings/PDF/TUP0/TUP077.pdf

The J-PARC linac operation is stable, however, the numbers of interlocked events due to single beam loss monitor (BLMP) is increasing. Recently, the counts is comparable to the number of RFQ trip, and a measure has been required for improvement of the operation efficiency. Thus, every event data has been analyzed and classified into three categories. It is found that there are characteristic signal or pattern of BLMP for every categories. Although the linac BLMP detector is standard, its setting parameters are differ from those of other two synchrotrons in the J-PARC. To optimize time resolution, the input impedance of its pre-amplifier is selected to be 50 and interlock is defined in raw signal height and width not integral signal of BLMP. Some new parameters has been tried to reduce unnecessary interlock.

Deuterium permeation behavior for damaged tungsten by ion implantation

Oya, Yasuhisa*; Li, X.*; Sato, Misaki*; Yuyama, Kenta*; Oyaizu, Makoto; Hayashi, Takumi; Yamanishi, Toshihiko; Okuno, Kenji*

Journal of Nuclear Science and Technology, 53(3), p.402 - 405, 2016/03

https://doi.org/10.1080/00223131.2015.1052583

The deuterium (D) permeation behaviors for ion damaged tungsten (W) by 3 keV D and 10 keV C were studied. The D permeability was obtained for un-damaged W at various temperatures. For both D and C implanted W, the permeability was clearly reduced. But, for the D implanted W, the permeability was recovered by heating at 1173 K and it was almost consistent with that for un-damaged W. In the case of C implanted W, the permeability was not recovered even if the sample was heated at 1173 K, indicating that the existence of carbon would prevent the recovery of permeation path in W. In addition, TEM observation showed the voids were grown by heating at 1173 K and not removed, showing the existence of damages would not largely influence on the hydrogen permeation behavior in W in the present study.

Process evaluation of use of High Temperature Gas-cooled Reactors to an ironmaking system based on Active Carbon Recycling Energy System

Hayashi, Kentaro*; Kasahara, Seiji; Kurihara, Kohei*; Nakagaki, Takao*; Yan, X.; Inagaki, Yoshiyuki; Ogawa, Masuro

ISIJ International, 55(2), p.348 - 358, 2015/02

https://doi.org/10.2355/isijinternational.55.348

Reducing coking coal consumption and CO emissions by application of iACRES (ironmaking system based on active carbon recycling energy system) was investigated using process flow modeling to show effectiveness of HTGRs (high temperature gas-cooled reactors) adoption to iACRES. Two systems were evaluated: a SOEC (solid oxide electrolysis cell) system using CO electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H produced by IS (iodine-sulfur) process. Both the effects on saving of the coking coal and reduction of CO emissions were greater in the RWGS system. It was the reason of the result that excess H which was not consumed in the RWGS reaction was used as reducing agent in the BF as well as CO. Heat balance in the HTGR, SOEC and RWGS modules were evaluated to clarify process components to be improved. Optimization of the SOEC temperature was desired to reduce Joule heat input for high efficiency operation of the SOEC system. Higher H production thermal efficiency in the IS process for the RWGS system is effective for more efficient HTGR heat utilization. The SOEC system was able to utilize HTGR heat to reduce CO emissions more efficiently by comparing CO emissions reduction per unit heat of HTGR.

Process evaluation of use of HTGRs to an ironmaking system based on active carbon recycling energy system (iACRES)

Hayashi, Kentaro*; Kasahara, Seiji; Kurihara, Kohei*; Nakagaki, Takao*; Yan, X.; Inagaki, Yoshiyuki; Ogawa, Masuro

Tanso Junkan Seitetsu Kenkyukai Saika Hokokusho; Tanso Junkan Seitetsu No Tenkai, p.42 - 62, 2015/02

Reducing coking coal consumption and CO emissions by application of HTGRs (high temperature gas-cooled reactors) to iACRES (ironmaking system based on active carbon recycling energy system) was investigated using process flow modeling. Two systems were evaluated: a SOEC (solid oxide electrolysis cell) system using CO electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H produced by IS (iodine-sulfur) process. Coking coal consumption was reduced from a conventional BF (blast furnace) steelmaking system by 4.3% in the SOEC system and 10.3% in the RWGS system. CO emissions were decreased by 3.4% in the SOEC system and 8.2% in the RWGS system. Remaining H from the RWGS reactor was used as reducing agent in the BF in the RWGS system. This was the reason of the larger reduction of coking coal consumption and CO emissions. Electricity generation for SOEC occupied most of HTGR heat usage in the SOEC system. H production in the IS process used most of the HTGR heat in the RWGS system. Optimization of the SOEC temperature for the SOEC system and higher H production thermal efficiency in the IS process for the RWGS system will be useful for more efficient heat utilization. One typical-sized BF required 0.5 HTGRs and 2 HTGRs for in the SOEC system and RWGS system, respectively. CO emissions reduction per unit heat input was larger in the SOEC system. Recycling H to the RWGS will be useful for smaller emissions per unit heat in the RWGS system.

R&D status on water cooled ceramic breeder blanket technology

Enoeda, Mikio; Tanigawa, Hisashi; Hirose, Takanori; Nakajima, Motoki; Sato, Satoshi; Ochiai, Kentaro; Konno, Chikara; Kawamura, Yoshinori; Hayashi, Takumi; Yamanishi, Toshihiko; et al.

Fusion Engineering and Design, 89(7-8), p.1131 - 1136, 2014/10

https://doi.org/10.1016/j.fusengdes.2014.01.035

The development of a Water Cooled Ceramic Breeder (WCCB) Test Blanket Module (TBM) is being performed as one of the most important steps toward DEMO blanket in Japan. Regarding the fabrication technology development using F82H, the fabrication of a real scale mockup of the back wall of TBM was completed. Also the assembling of the complete box structure of the TBM mockup and planning of the pressurization testing was studied. The development of advanced breeder and multiplier pebbles for higher chemical stability was performed for future DEMO blanket application. From the view point of TBM test result evaluation and DEMO blanket performance design, the development of the blanket tritium simulation technology, investigation of the TBM neutronics measurement technology and the evaluation of tritium production and recovery test using D-T neutron in the Fusion Neutronics Source (FNS) facility has been performed.

Coupling atmospheric ammonia exchange process over a rice paddy field with a multi-layer atmosphere-soil-vegetation model

Katata, Genki; Hayashi, Kentaro*; Ono, Keisuke*; Nagai, Haruyasu; Miyata, Akira*; Mano, Masayoshi*

Agricultural and Forest Meteorology, 180, p.1 - 21, 2013/10

https://doi.org/10.1016/j.agrformet.2013.05.001

A multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) was modified to calculate the NH exchange fluxes over a paddy field. The heat transfer at the paddy water layer and the dry deposition of water-soluble gases such as NH and SO onto the wet canopy, as well as the emission potentials of NH from the rice foliage and the surface of floodwater or soil were incorporated into the model. The modified model reproduced the observed surface and NH fluxes, paddy water temperature, and soil temperature and moisture during both the fallow and cropping seasons. The "recaptured fraction" was defined as the ratio of the amount of volatilized NH recaptured by the foliage to the total amount. Numerical experiments using the modified model with varying emission potentials of NH showed that the recaptured fraction increased with an increase in the leaf area index (LAI) and saturated when LAI 1 because of the limitation of stomatal uptake.