Unified mercury radioactivity monitoring system at J-PARC and its operation experiences

Harada, Masahide; Sekijima, Mitsuaki*; Morikawa, Noriyuki*; Masuda, Shiho; Kinoshita, Hidetaka; Sakai, Kenji; Kai, Tetsuya; Kasugai, Yoshimi; Muto, Giichi*; Suzuki, Akio*; et al.

JPS Conference Proceedings (Internet), 33, p.011099_1 - 011099_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011099

In MLF at J-PARC, a unified mercury radioactivity monitor (UHAM) is installed to find an indication of failure of the mercury target and loop system by detecting radioactive materials leaked from the system with a -ray energy analysis with Germanium semi-conductor detectors (Ge detectors). It is composed of three units of sampling port and radiation monitors: (1) HAM for interstitial helium gas layer between the mercury vessel and surrounding water shroud of the mercury target, (2) CAM for atmosphere in the hot cell where the target loop is operated and (3) VAM for helium gas in the helium vessel where the target vessel is installed. Once any leakages of radioactive materials are detected, an alarm signal is issued immediately to the accelerator control system to stop beam operation. Software and hardware have been upgraded yearly. For example, two Ge detectors are used for HAM for redundancy, NaI Scintillation detectors are also used as supplemental for the Ge detector to keep availability of the system for high counting rate event. In April 2015, the UHAM activated when a small water coolant leakage from the water shroud of the mercury target occurred. VAM detected an abnormal increase of the counting rate in the helium vessel. It was also indicated that the measured radioactive nuclides were generated from the activation of the coolant (water) in the water shroud and not from the mercury.

Precise determination of C level structure by -ray spectroscopy

Hosomi, Kenji; Ma, Y.*; Ajimura, Shuhei*; Aoki, Kanae*; Dairaku, Seishi*; Fu, Y.*; Fujioka, Hiroyuki*; Futatsukawa, Kenta*; Imoto, Wataru*; Kakiguchi, Yutaka*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2015(8), p.081D01_1 - 081D01_8, 2015/08

https://doi.org/10.1093/ptep/ptv113

Level structure of the C hypernucleus was precisely determined by means of -ray spectroscopy. We identified four -ray transitions via the C reaction using a germanium detector array, Hyperball2. The spacing of the ground-state doublet was measured to be (stat) (syst)keV from the direct transition. Excitation energies of the and states were measured to be , keV and , keV, respectively. The obtained level energies provide definitive references for the reaction spectroscopy of hypernuclei.

Initial dissolution rate of a Japanese simulated high-level waste glass P0798 as a function of pH and temperature measured by using micro-channel flow-through test method

Inagaki, Yaohiro*; Makigaki, Hikaru; Idemitsu, Kazuya*; Arima, Tatsumi*; Mitsui, Seiichiro; Noshita, Kenji*

Journal of Nuclear Science and Technology, 49(4), p.438 - 449, 2012/04

https://doi.org/10.1080/00223131.2012.669246

Dissolution tests were performed for a simulated HLW glass by using a Micro-Channel Flow-Through (MCFT) test to evaluate the initial dissolution rate, , as a function of pH and temperature. The results indicated that the shows a "V-shaped" pH dependence at 25C, which is almost consistent with the previous results measured by using other test methods including Single Pass Flow-Through (SPFT) test. At elevated temperatures, however, the shows a "U-shaped" pH dependence with a flat bottom at neutral pH, which differs from the previous results. The results also indicated that the MCFT provided a higher value of the with a steep slope of pH dependence than the SPFT results at basic pH from 8 to 11 at 90C. With respect to the temperature dependence, the increases with temperature according to an Arrhenius law at any pH, and the apparent activation energy increases with pH, which suggests that the dissolution mechanism can change depending on pH.

Influence of Great East Japan Earthquake on neutron target station in J-PARC

Sakai, Kenji; Futakawa, Masatoshi; Takada, Hiroshi; Sakamoto, Shinichi; Maekawa, Fujio; Kinoshita, Hidetaka; Seki, Masakazu; Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; et al.

Proceedings of 20th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-20) (USB Flash Drive), 6 Pages, 2012/03

This report investigates behaviors and damages of each component in a neutron target station of the MLF at the J-PARC at the time of the Great East Japan Earthquake (GEJE). At the date of the GEJE, in the MLF, strong quakes were detected at several instruments, an external power supply were lost, all of the circulation systems were shut down automatically, and a hydrogen gas was released as planned. Leakage of activation liquids and gases did not occur. While, the quakes made gaps between shield blocks and ruptured external pipe lines for air and water by subsidence. But significant damages on the components of the target station were not found though a loss of compressed air supply affected lock systems with air cylinders and pneumatic operation values. These results substantiated a validity of safety design on the target station for emergency accidents.

Shielding experiments at high energy accelerators of Fermilab, 2; Spatial distribution measurement of reaction rate behind the shield and its application for Moyer model

Yashima, Hiroshi*; Kasugai, Yoshimi; Matsuda, Norihiro; Matsumura, Hiroshi*; Iwase, Hiroshi*; Kinoshita, Norikazu*; Mokhov, N.*; Leveling, A.*; Boehnlein, D.*; Vaziri, K.*; et al.

Progress in Nuclear Science and Technology (Internet), 1, p.48 - 51, 2011/02

https://doi.org/10.15669/pnst.1.48

The shielding experiment was performed at the anti-proton production target station in Fermi National Accelerator Laboratory. Aluminum, Bismath, Niobium, Copper and Indium samples were placed behind the shields. After irradiation, induced activities of samples were measured by using HPGe detector. The spatial distribution of reaction rate of samples which were placed behind the iron and concrete shields were obtained. The measured data shows that the reaction rates on the outer surfaces of the iron and concrete shields increases toward the downstream of the target. The obtained reaction rates were also fitted to Moyer's formula, and the attenuation lengths for iron and concrete shields were obtained.

Evaluation of HLW glass dissolution/alteration kinetics by using micro-channel flow-through test method; Initial glass dissolution rate as a function of pH and temperature

Inagaki, Yaohiro*; Sakatani, Keiichi*; Yamamura, Yuki*; Mitsui, Seiichiro; Noshita, Kenji*; Miura, Yoshiyuki*; Kanehira, Norio*; Ochi, Eiji*; Mukunoki, Atsushi*; Chiba, Tamotsu*

Dai-7-Kai Saishori, Risaikuru Bukai Semina Tekisuto, p.136 - 137, 2011/01

Conventional static test methods are not appropriate to evaluate glass dissolution behavior at an arbitrarily-fixed condition due to compositional change of the solution with glass dissolution. In this study, we applied a newly-devised micro-channel flow-through test method to measurement of the initial dissolution rates of Japanese simulated waste glasses, JAEA-P0798 and JNFL-KMOC, at arbitrarily-fixed conditions and we evaluated temperature and pH dependence of glass dissolution. The results showed that the initial dissolution rate increased with temperature and had "V-shaped" pH dependence at each temperature.

Design, construction and operation of general control system of Materials and Life Science Experimental Facility (MLF-GCS) in J-PARC

Sakai, Kenji; Oi, Motoki; Kai, Tetsuya; Watanabe, Akihiko; Nakatani, Takeshi; Higemoto, Wataru; Shimomura, Koichiro*; Kinoshita, Hidetaka; Kaminaga, Masanori

JAEA-Technology 2009-042, 44 Pages, 2009/08

JAEA-Technology-2009-042.pdf:35.33MB

A general control system for the Materials and Life Science Experimental Facility (MLF-GCS) at J-PARC has an advanced and independent system for control of the mercury target, including a large amount of mercury, three moderators with supercritical hydrogen, and cooling systems with radioactive water. Although the MLF-GCS is an independent system, it works closely with the accelerator and other facility control systems within J-PARC. The MLF have succeeded in the first proton beam injection and neutron beam generation in May 2008, and succeeded the muon beams generation in September 2008. The design and construction of the MLF-GCS has finished before the first proton beam injection. It has been operated stably and efficiently in the off- and on- beam commissioning. This paper reports on the design, construction and operation of the MLF-GCS.

Measurement of initial dissolution rate of P0798 simulated HLW glass by using micro-reactor flow-through test method

Makigaki, Hikaru*; Inagaki, Yaohiro*; Idemitsu, Kazuya*; Arima, Tatsumi*; Mitsui, Seiichiro; Bamba, Tsunetaka; Noshita, Kenji*

Materials Research Society Symposium Proceedings, Vol.1193, p.307 - 314, 2009/05

https://doi.org/10.1557/PROC-1193-307

By using micro-reactor flow-through test method we measured the initial dissolution rate of P0798 glass at 25C as a function of pH between 5.6 and 12. The results showed that the initial dissolution rate determined by dissolution rate of Si has "V-shaped" pH dependency similar to R7T7 glass reported by CEA, France. We also measured the initial dissolution rate at pH 5.6 as a function of temperature between 25 and 90C, and the activation energy was evaluated to be 51 kJ/mol, which value is slightly smaller than that of R7T7 glass at pH 9 reported by CEA. On the basis of these results and comparison, we discussed the dissolution kinetics of P0798 glass.

Construction status of a general control system for the Materials and Life Science Experimental Facility (MLF) at J-PARC

Sakai, Kenji; Oi, Motoki; Kai, Tetsuya; Kinoshita, Hidetaka; Kawasaki, Susumu; Watanabe, Akihiko; Kaminaga, Masanori; Futakawa, Masatoshi

Nuclear Instruments and Methods in Physics Research A, 600(1), p.75 - 77, 2009/02

https://doi.org/10.1016/j.nima.2008.11.122

In order to operate all equipment of the Materials and Life Science Experimental Facility (MLF) safely and efficiently, the MLF general control system (MLF-GCS) is designed to have several subsystems such as the facility control system centering on the control of the targets, interlock systems for protecting personnel, machine and the neutron target, and so on. Although it is an independent system, the MLF-GCS should also be as a part of the control system of the whole J-PARC operated from the central control room (CCR). The construction of MLF-GCS has been almost finished, and its performance test is in progress to check and adjust remote operations and integral interlocks from the control room of MLF. This paper gives an overview of the MLF-GCS and reports its construction status.

Development of beam monitor DAQ system for 3NBT at J-PARC

Oi, Motoki; Kai, Tetsuya; Meigo, Shinichiro; Kinoshita, Hidetaka; Sakai, Kenji; Sakamoto, Shinichi; Kaminaga, Masanori; Kato, Takashi; Kato, Tadahiko*

Europhysics Conference Abstracts, 29J, 6 Pages, 2005/00

The 3GeV proton beam transport facility (3NBT) is a high-intensity proton beam line from the 3GeV Rapid Cycling Synchrotron (RCS) to the Material and Life science Facility (MLF) at Japan Proton Accelerator Research Complex (J-PARC). In order to allow hands-on maintenance, a design criterion has been that the average beam loss at 3NBT be less than 1W/m. The systems for beam monitoring and magnet power control play an important role. In J-PARC, the Experimental Physics and Industrial Control System (EPICS) [1] will be used for the main control system. For the proton beam monitor system of 3NBT, EPICS is used and it has to work at 25Hz. In this study, a data acquisition system for the proton beam monitors is presented that has been developed with EPICS. Its performance has been investigated under 25Hz frequency condition.