Stepwise renewal of JRR-3 process control computer system

Isaka, Koji; Suwa, Masayuki; Kimura, Kazuya; Suzuki, Makoto; Ikekame, Yoshinori; Nagadomi, Hideki

JAEA-Technology 2021-039, 48 Pages, 2023/02

JAEA-Technology-2021-039.pdf:6.97MB

JRR-3 Process control system is used from the initial criticality (1990) after remodeling JRR- 3 as equipment used for monitoring and control of flow rate, temperature, pressure, water level, etc. of coolant and operation of nuclear reactor equipment, and it became necessary to renew as the aging progressed and spare parts could not be obtained sufficiently. Upon renewal, from the viewpoint of ensuring conservation of the core such as decay heat removal and minimizing the impact on reactor users and minimizing costs, it is important not to stop long-term reactor shutdown we planned to divide it into three stages and make it on a continuous basis. This report summarizes the renewal plan and renewal work divided into three stages.

Evidence for weak spin-orbit interaction experienced by Cooper pairs in the spin-triplet superconductor UPt; Pt-NMR study

Aoyama, Taisuke*; Kotegawa, Hisashi*; Kimura, Noriaki*; Yamamoto, Etsuji; Haga, Yoshinori; Onuki, Yoshichika*; To, Hideki*

Journal of the Physical Society of Japan, 88(6), p.064706_1 - 064706_7, 2019/06

https://doi.org/10.7566/JPSJ.88.064706

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

https://doi.org/10.3390/qubs1030009

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

Sodium experiments on natural circulation decay heat removal and 3D simulation of plenum thermal hydraulics

Kamide, Hideki; Ono, Ayako; Kimura, Nobuyuki; Endo, Junji*; Watanabe, Osamu*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Safe Technologies and Sustainable Scenarios (FR-13), Companion CD (CD-ROM), 11 Pages, 2015/04

http://www-pub.iaea.org/MTCD/Publications/PDF/SupplementaryMaterials/P1665CD/Track3_Safety.pdf#page=21

http://www.iaea.org/nuclearenergy/nuclearpower/Downloadable/Meetings/2013/2013-03-04-03-07-CF-NPTD/T3.3/T3.3.kamide.pdf

Natural circulation decay heat removal is one of the significant issues for fast reactor safety, especially in long term station blackout events. Several sodium experiments were carried out using a 7-subassmbly core model for core thermal hydraulics under natural circulation conditions and for onset transients of natural circulation in a decay heat removal system (DHRS) including natural draft. Significant heat removal via inter-wrapper flow was confirmed in the experiments. Solidification of sodium in an air cooler is one of key issues in loss of heat sink events. Natural circulation characteristics under long-term decay heat removal were also obtained. Multi-dimensional phenomena, e.g., thermal stratification and bypass flow in plenums and/or heat exchangers, may influence the natural circulation. Thus, 3D simulation method was developed for entire region in the primary loop. Comparison of temperature distributions in a DHRS heat exchanger between experiment and analysis was done.

Development of NRD, 1; Developments of a LaBr scintillation detector system for neutron resonance densitometry

Koizumi, Mitsuo; Tsuchiya, Harufumi; Kitatani, Fumito; Harada, Hideo; Takamine, Jun; Kureta, Masatoshi; Seya, Michio; Kimura, Atsushi; Iimura, Hideki; Becker, B.*; et al.

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-35-Kai Nenji Taikai Rombunshu (Internet), 8 Pages, 2015/01

We have proposed neutron resonance densitometry (NRD) as a method to quantify special nuclear materials in particle-like debris of melted fuel. NRD is a combination of neutron resonance transmission analysis (NRTA), and neutron resonance capture analysis (NRCA) (and prompt -ray analysis (PGA)). NRCA/PGA is used to identify contaminant elements, which is difficult to be detected by NRTA. To observe rays emitted in neutron capture reaction, a spectrometer consisting of LaBr scintillation detectors has been constructed. A newly installed data acquisition system enables us to measure 500 k event/s for each 8-channel inputs. In this presentation, the research and development of NRD is introduced and the status of the development of the spectrometer system is given as well.

Nanoscale diffusion tracing by radioactive Li tracer

Ishiyama, Hironobu*; Jeong, S.-C.*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Imai, Nobuaki*; Miyatake, Hiroari*; Oyaizu, Mitsuhiro*; Katayama, Ichiro*; Osa, Akihiko; Otokawa, Yoshinori; et al.

Japanese Journal of Applied Physics, 53(11), p.110303_1 - 110303_4, 2014/11

https://doi.org/10.7567/JJAP.53.110303

Study on high cycle thermal fatigue in mixing tee; Evaluation of transfer characteristics of temperature fluctuation from fluid to structure

Kimura, Nobuyuki; Kobayashi, Jun; Kameyama, Yuri*; Nagasawa, Kazuyoshi*; Ezure, Toshiki; Ono, Ayako; Kamide, Hideki

JAEA-Research 2014-009, 104 Pages, 2014/07

JAEA-Research-2014-009.pdf:15.23MB
JAEA-Research-2014-009-appendix(CD-ROM).pdf:17.88MB

In this study, water experiments (WATLON) were carried out to clarify the unsteady behavior of heat transfer under wall jet condition in the mixing tee. In experiments, heat transfer coefficients between fluid and wall in the mixing region were obtained from temperature measurements using thermocouples (movable tree type in fluid and embedded type in wall). To clarify the relation between the local velocity and the wall temperature, those were measured simultaneously by the Particle Image Velocimetry (PIV) and the thermocouple measurement, respectively. Sampling time of the velocity by the PIV and the temperature by the thermocouple were synchronized in the measurement. The experimental results showed that the heat transfer coefficient was from 2 - 6 time larger than the reference value predicted by the Dittus-Boelter correlation in straight pipes and was increased as the local velocity near the wall.

Developments of a LaBr scintillation detector system for neutron resonance densitometry (NRD)

Koizumi, Mitsuo; Tsuchiya, Harufumi; Kitatani, Fumito; Harada, Hideo; Takamine, Jun; Kureta, Masatoshi; Seya, Michio; Kimura, Atsushi; Iimura, Hideki; Becker, B.*; et al.

Proceedings of INMM 55th Annual Meeting (Internet), 7 Pages, 2014/07

Occurrence and potential activity of denitrifiers and methanogens in groundwater at 140 m depth in Pliocene diatomaceous mudstone of northern Japan

Katsuyama, Chie*; Nashimoto, Hiroaki*; Nagaosa, Kazuyo*; Ishibashi, Tomotaka*; Furuta, Kazuki*; Kinoshita, Takeshi*; Yoshikawa, Hideki; Aoki, Kazuhiro; Asano, Takahiro*; Sasaki, Yoshito; et al.

FEMS Microbiology Ecology, 86(3), p.532 - 543, 2013/12

https://doi.org/10.1111/1574-6941.12179

Anaerobic microbial activity has a major influence on the subsurface environment, and should be considered in subsurface activities including the construction of radioactive waste repositories. We investigated denitrification and methanogenesis in anoxic groundwater from 140 m depth in two boreholes, where the redox potential fluctuated. The average maximum potential denitrification rates, measured under anaerobic conditions in the two boreholes using an N tracer. Methanogenesis candidates were detected by 16S rRNA gene analysis. Although the stable isotope signatures suggested that some of the dissolved methane was of biogenic origin, no potential for methane production was evident during the incubations. The groundwater at 140 m depth did not contain oxygen, had an Eh ranging from -144 to 6.8 mV, and was found to be a potential field for denitrification.

Fundamental behavior of vortex cavitation in a 1/22 scaled upper plenum model of sodium-cooled fast reactor; Influences of kinematic viscosity and system pressure

Ezure, Toshiki; Ito, Kei; Onojima, Takamitsu; Kimura, Nobuyuki; Kamide, Hideki

Proceedings of 8th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-8) (USB Flash Drive), 7 Pages, 2012/12

In this study, water experiments were performed in the 1/22 scaled upper plenum model of JSFR. Occurrence behavior of vortex cavitation was grasped quantitatively by means of the visualization and image analyses under several conditions of kinematic viscosity ) and pressure (). The experimental results showed that the vortex cavitation has dependence on the variation of and P. The increase of at least in the present small model, leaded to the restriction of cavitation as assumed by Burgers model. And also, the restriction level of vortex cavitation according to the increase was smaller than the evaluation using cavitation factor.