Differential pressure rise event for filters of HTTR primary helium gas circulators, 1; Investigation of differential pressure rise event

Nemoto, Takahiro; Arakawa, Ryoki; Kawakami, Satoru; Nagasumi, Satoru; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; Furusawa, Takayuki; Inoi, Hiroyuki; et al.

JAEA-Technology 2023-005, 33 Pages, 2023/05

JAEA-Technology-2023-005.pdf:5.25MB

During shut down of the HTTR (High Temperature engineering Test Reactor) RS-14 cycle, an increasing trend of filter differential pressure for the helium gas circulator was observed. In order to investigate this phenomenon, the blower of the primary helium purification system was disassembled and inspected. As a result, it is clear that the silicon oil mist entered into the primary coolant due to the deterioration of the charcoal filter performance. The replacement and further investigation of the filter are planning to prevent the reoccurrence of the same phenomenon in the future.

Data report of ROSA/LSTF experiment SB-SG-10; Recovery actions from multiple steam generator tube rupture accident

Takeda, Takeshi

JAEA-Data/Code 2018-004, 64 Pages, 2018/03

JAEA-Data-Code-2018-004.pdf:3.33MB

Experiment SB-SG-10 was conducted on November 17, 1992 using LSTF. Experiment simulated recovery actions from multiple steam generator (SG) tube rupture accident in PWR. Primary pressure was kept higher than broken SG secondary-side pressure due to coolant injection from high pressure injection (HPI) system into cold and hot legs even after start of full opening of intact SG relief valve (RV). Full opening of power-operated relief valve (PORV) in pressurizer (PZR) resulted in pressure equalization between primary and broken SG systems as well as PZR liquid level recovery. Broken SG RV opened once after start of intact SG RV full opening. Core was filled with saturated or subcooled liquid through experiment. Significant natural circulation prevailed in intact loop after start of intact SG RV full opening. Significant thermal stratification appeared in hot legs especially during time period of HPI coolant injection into hot legs.

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 1; Pulsed spallation neutron source

Takada, Hiroshi; Haga, Katsuhiro; Teshigawara, Makoto; Aso, Tomokazu; Meigo, Shinichiro; Kogawa, Hiroyuki; Naoe, Takashi; Wakui, Takashi; Oi, Motoki; Harada, Masahide; et al.

Quantum Beam Science (Internet), 1(2), p.8_1 - 8_26, 2017/09

https://doi.org/10.3390/qubs1020008

At the Japan Proton Accelerator Research Complex (J-PARC), a pulsed spallation neutron source provides neutrons with high intensity and narrow pulse width to promote researches on a variety of science in the Materials and life science experimental facility. It was designed to be driven by the proton beam with an energy of 3 GeV, a power of 1 MW at a repetition rate of 25 Hz, that is world's highest power level. A mercury target and three types of liquid para-hydrogen moderators are core components of the spallation neutron source. It is still on the way towards the goal to accomplish the operation with a 1 MW proton beam. In this paper, distinctive features of the target-moderator-reflector system of the pulsed spallation neutron source are reviewed.

Shielding design of ITER pressure suppression system

Yamauchi, Michinori*; Sato, Satoshi; Nishitani, Takeo; Kawasaki, Hiromitsu*

Proceedings of 21st IEEE/NPSS Symposium on Fusion Engineering (SOFE 2005) (CD-ROM), 4 Pages, 2005/09

https://doi.org/10.1109/FUSION.2005.252902

no abstracts in English

Study on control characteristics for HTTR hydrogen production system with mock-up test facility; System controllability test for fluctuation of chemical reaction

Inaba, Yoshitomo; Ohashi, Hirofumi; Nishihara, Tetsuo; Sato, Hiroyuki; Inagaki, Yoshiyuki; Takeda, Tetsuaki; Hayashi, Koji; Takada, Shoji

Nuclear Engineering and Design, 235(1), p.111 - 121, 2005/01

https://doi.org/10.1016/j.nucengdes.2004.08.034

Prior to the connection of a hydrogen production plant to the HTTR, the fluctuation tests of the chemical reaction in the steam reformer with the mock-up test facility of the HTTR hydrogen production system were carried out for the establishment and demonstration of the control technology. As a result, it was shown that the HTTR hydrogen production system with the same control system as the mock-up test facility can provide stable controllability for any disturbance at the steam reformer without the influence to the reactor. In addition, a dynamic simulation code for the HTTR hydrogen production system was verified with the obtained test data.

Leak-tightness characteristics concerning the containment structures of the HTTR

Sakaba, Nariaki; Iigaki, Kazuhiko; Kondo, Masaaki; Emori, Koichi

Nuclear Engineering and Design, 233(1-3), p.135 - 145, 2004/10

https://doi.org/10.1016/j.nucengdes.2004.08.023

The containment structures of the HTTR consist of the reactor containment vessel, the service area, and the emergency air purification system, which minimise the release of fission products in postulated accidents which lead to fission product release from the reactor facilities. The reactor containment vessel is designed to withstand the temperature and pressure transients and to be leak-tight in the case of a rupture of the primary concentric hot gas duct, etc. The pressure inside the service area is maintained at a negative pressure by the emergency air purification system. The emergency air purification system will also remove airborne radio-activity and will maintain a correct pressure in the service area. The leak-tightness characteristics of the containment structures are described in this paper. The measured leakage rates of the reactor containment vessel were enough less than the specified leakage limit of 0.1%/d confirmed during the commissioning tests and annual inspections. The service area was kept the design pressure well below its allowable limitation by the emergency air purification system which filter efficiency of particle removal and iodine removal were well over the limited values. The obtained data demonstrates that the reactor containment structures were fabricated to minimise the release of fission products in the postulated accidents with fission product release from the reactor facilities.

Analysis of pressure- and temperature- induced steam generator tube rupture during PWR severe accident initiated from station blackout

Hidaka, Akihide; Maruyama, Yu; Nakamura, Hideo

Proceedings of 6th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operations and Safety (NUTHOS-6) (CD-ROM), 15 Pages, 2004/00

Severe accident studies showed that Direct Containment Heating issue was resolved for PWRs because a creep rupture at pressurizer surge line would occur prior to the melt-through of Reactor Pressure Vessel during station blackout (TMLB'). However, it was recently concerned that, if the secondary system is depressurized during TMLB', the creep rupture at SG U-tubes would occur earlier than the surge line. This pressure- and temperature-induced SG U-tube rupture (PTI-SGTR) is not preferable because of the increase in offsite consequences. The SCDAP/RELAP5 analyses by USNRC showed that the surge line would fail earlier than the U-tubes. However, the analyses used a coarse nodilization for steam mixing at the SG inlet plenum that could affect the temperature of U-tubes. To investigate the effect of steam mixing, an analysis was performed with MELCOR1.8.4. The analysis showed that the surge line would fail earliest during TMLB' while the U-tubes could fail earliest during TMLB' with secondary system depressurization. Further investigation is needed for occurrence conditions of PTI-SGTR.

In situ EXAFS study on GeS glass under high-pressure

Miyauchi, Koichi*; Qiu, J.*; Shojiya, Masanori*; Kawamoto, Yoji*; Kitamura, Naoyuki*; Fukumi, Kohei*; Katayama, Yoshinori; Nishihata, Yasuo

Solid State Communications, 124(5-6), p.189 - 193, 2002/10

https://doi.org/10.1016/S0038-1098(02)00489-1

A GeS glass was compressed up to 8 GPa at room temperature, heated up to 270 C under 8 GPa and then decompressed to ambient pressure at room temperature, using a large volume high-pressure apparatus. The local structural-changes around Ge were examined by means of EXAFS method. The Ge-S bond length became monotonously short with increasing applied-pressure up to 8 GPa at room temperature. When the specimen was heated to 270 C under 8 GPa, however, the vond length became slightly long. The elongated bond lengthe was almost kept even after the temperature was descended to room tempertature. In decompression process, the bond length became gradually long with releasing applied-pressure down to 2 GPa, following a change in compression process. Below 2 GPa, however, the Ge-S bond length was largely elongated, being lnger than the initial one. No significant change of coordination number was found in the compression and decompression processes up to 8 GPa. This change canbe explained by a combined effect of elastic and inelastic structural-changes.

ROSA/LSTF experiments on low-pressure natural circulation heat removal for next-generation PWRs

Yonomoto, Taisuke; Otsu, Iwao

Proceedings of 12th Pacific Basin Nuclear Conference (PBNC 2000), Vol.1, p.317 - 329, 2000/00

no abstracts in English

Proposal of safety design methodologies for an HTGR-hydrogen production system; Mainly on countermeasures against fire and explosion

Nishihara, Tetsuo; Hada, Kazuhiko; Shiozawa, Shusaku

JAERI-Research 97-022, 110 Pages, 1997/03

JAERI-Research-97-022.pdf:4.1MB

no abstracts in English