Thermal-hydraulic analyses of the High-Temperature engineering Test Reactor for loss of forced cooling at 30% reactor power

Takamatsu, Kuniyoshi

Annals of Nuclear Energy, 106, p.71 - 83, 2017/08

http://doi.org/10.1016/j.anucene.2017.03.032

The HTTR, which is the only HTGR having inherent safety features in Japan, conducted a safety demonstration test involving a loss of both reactor reactivity control and core cooling. The paper shows thermal-hydraulics during the LOFC test at an initial power of 30% reactor power (9 MW), when the insertion of all control rods was disabled and all gas circulators were tripped to reduce the coolant flow rate to zero. The analytical results could show that the downstream of forced convection caused by the HPS pushes down the upstream by natural convection in the fuel assemblies; however, the forced convection has little influence on the core thermal-hydraulics without the reactor outlet coolant temperature. As a result, the three-dimensional thermal-phenomena inside the RPV during the LOFC test could be understood qualitatively.

Experiments and validation analyses of HTTR on loss of forced cooling under 30% reactor power

Takamatsu, Kuniyoshi; Tochio, Daisuke; Nakagawa, Shigeaki; Takada, Shoji; Yan, X.; Sawa, Kazuhiro; Sakaba, Nariaki; Kunitomi, Kazuhiko

Journal of Nuclear Science and Technology, 51(11-12), p.1427 - 1443, 2014/11

https://doi.org/10.1080/00223131.2014.967324

In a safety demonstration test involving a loss of both reactor reactivity control and core cooling, HTGRs such as the HTTR, which is the only HTGR in Japan, demonstrate that the reactor power would stabilize spontaneously. In the test at an initial power of 30%, when the insertion of all control rods was disabled and all gas circulators were tripped to reduce the coolant flow rate to zero, a reactor transient was initiated and examined. The results confirmed that the reactor power would decrease immediately and become effectively zero.

Annular core experiments in HTTR's start-up core physics tests

Fujimoto, Nozomu; Yamashita, Kiyonobu*; Nojiri, Naoki; Takeuchi, Mitsuo; Fujisaki, Shingo; Nakano, Masaaki*

Nuclear Science and Engineering, 150(3), p.310 - 321, 2005/07

https://doi.org/10.13182/NSE03-79

Annular cores were formed in startup-core-physics tests of the High Temperature Engineering Test Reactor (HTTR) to obtain experimental data for verification of calculation codes. The first criticality, control rod positions at critical conditions, neutron flux distribution, excess reactivity etc. were measured as representative data. These data were evaluated with Monte Carlo code MVP that can consider the heterogeneity of coated fuel particles (CFP) distributed randomly in fuel compacts directly. It was made clear that the heterogeneity effect of CFP on reactivity for annular cores is smaller than that for fully-loaded cores. Measured and calculated effective multiplication factors (k) were agreed with differences less than 1%k. Measured neutron flux distributions agreed with calculated results. The revising method was applied for evaluation of excess reactivity to exclude negative shadowing effect of control rods. The revised and calculated excess reactivity agreed with differences less than 1%k/k.

Proceedings of the 11th International Workshop on Ceramic Breeder Blanket Interactions; December 15 - 17, 2003, Tokyo, Japan

Enoeda, Mikio

JAERI-Conf 2004-012, 237 Pages, 2004/07

JAERI-Conf-2004-012.pdf:44.1MB

This report is the Proceedings of "the Eleventh International Workshop on Ceramic Breeder Blanket Interactions" which was held as a workshop on ceramic breeders Under the IEA Implementing Agreement on the Nuclear Technology of Fusion Reactors, and the Japan-US Fusion Collaboration Framework. In the workshop, information exchange was performed for designs of solid breeder blankets and test blankets in EU, Russia and Japan, recent results of irradiation tests, HICU, EXOTIC-8 and the irradiation tests by IVV-2M, modeling study on tritium release behavior of LiTiO and other breeders, fabrication technology developments and characterization of the LiTiO and LiSiO pebbles, research on measurements and modeling of thermo-mechanical behaviors of LiTiO and LiSiO pebbles, and interfacing issues, such as, fabrication technology for blanket box structure, neutronics experiments of blanket mockups by fusion neutron source and tritium recovery system.

Cause and countermeasure for heat up of HTTR core support plate at power rise tests

Fujimoto, Nozomu; Takada, Eiji*; Nakagawa, Shigeaki; Tachibana, Yukio; Kawasaki, Kozo; Saikusa, Akio; Kojima, Takao; Iyoku, Tatsuo

JAERI-Tech 2001-090, 69 Pages, 2002/01

JAERI-Tech-2001-090.pdf:7.88MB

HTTR has carried out many kinds of tests as power rise tests in which reactor power rises step by step after attained the first criticality. In the tests, temperature of a core support plate showed higher results than expected value at each power level, the temperature was expected to be higher than the maximum working temperature at 100% power level. Therefore, tests under the high temperature test operation mode, in which the core flow rate was different, were carried out to predict the temperature at 100% power precisely, and investigate the cause of the temperature rise. From the investigation, it was clear that the cause was gap flow in a core support structure. Furthermore, it was estimated that the temperature of the core support plate rose locally due to change in gap width between the core support plate and a seal plate due to change in core pressure drop. The maximum working temperature of the core support plate was revised. The integrity of core support plate under the revised maximum working temperature condition was confirmed by stress analyses.

Control rod position and temperature coefficients in HTTR power-rise tests; Interim report

Fujimoto, Nozomu; Nojiri, Naoki; Takada, Eiji*; Saito, Kenji; Kobayashi, Shoichi; Sawahata, Hiroaki; Kokusen, Shigeru

JAERI-Tech 2000-091, 49 Pages, 2001/03

JAERI-Tech-2000-091.pdf:2.0MB

no abstracts in English

Mechanical and thermal properties of 2-D and 3-D SiC/SiC Composites

Yamada, Reiji; Taguchi, Tomitsugu; Igawa, Naoki

Journal of Nuclear Materials, 283-287(Part.2), p.574 - 578, 2000/12

https://doi.org/10.1016/S0022-3115(00)00144-6

no abstracts in English

Results of HTTR criticality tests

Fujimoto, Nozomu; Takeuchi, Mitsuo; Fujisaki, Shingo; Nakano, Masaaki*; Yamashita, Kiyonobu; Mogi, Haruyoshi

UTNL-R-0378, p.5.1 - 5.10, 1999/00

no abstracts in English

Neutronics analysis on helium production control in stainless steel by neutron spectral tailoring in the JMTR

Shimakawa, Satoshi; ; Nagao, Yoshiharu;

JAERI-Tech 95-023, 26 Pages, 1995/03

JAERI-Tech-95-023.pdf:1.08MB

no abstracts in English

NRTA data processing system: PROMAC-J

Ikawa, Koji; Ihara, Hitoshi; Nishimura, Hideo

JAERI-M 93-182, 160 Pages, 1993/09

JAERI-M-93-182.pdf:3.31MB

no abstracts in English