Verification and validation of the THYTAN code for the graphite oxidation analysis in the HTGR systems

Shimazaki, Yosuke; Isaka, Kazuyoshi; Nomoto, Yasunobu; Seki, Tomokazu; Ohashi, Hirofumi

JAEA-Technology 2014-038, 51 Pages, 2014/12

JAEA-Technology-2014-038.pdf:3.84MB

The analytical models for the evaluation of graphite oxidation were implemented into the THYTAN code, which employs the mass balance and a node-link computational scheme to evaluate tritium behavior in the High Temperature Gas-cooled Reactor (HTGR) systems for hydrogen production, to analyze the graphite oxidation during the air or water ingress accidents in the HTGR systems. This report describes the analytical models of the THYTAN code in terms of the graphite oxidation analysis and its verification and validation (V&V) results. Mass transfer from the gas mixture in the coolant channel to the graphite surface, diffusion in the graphite, graphite oxidation by air or water, chemical reaction and release from the primary circuit to the containment vessel by a safety valve were modeled to calculate the mass balance in the graphite and the gas mixture in the coolant channel. The computed solutions using the THYTAN code for simple questions were compared to the analytical results by a hand calculation to verify the algorithms for each implemented analytical model. A representation of the graphite oxidation experimental was analyzed using the THYTAN code, and the results were compared to the experimental data and the computed solutions using the GRACE code, which was used for the safety analysis of the High Temperature Engineering Test Reactor (HTTR), in regard to corrosion depth of graphite and oxygen concentration at the outlet of the test section to validate the analytical models of the THYTAN code. The comparison of THYTAN code results with the analytical solutions, experimental data and the GRACE code results showed the good agreement.

Effect of air-oxidation on the thermal diffusivity of the nuclear grade 2-dimensional carbon fiber reinforced carbon/carbon composite

Sogabe, Toshiaki; Ishihara, Masahiro; Baba, Shinichi; Tachibana, Yukio; Yamaji, Masatoshi*; Iyoku, Tatsuo; Hoshiya, Taiji*

Materials Science Research International, 9(3), p.235 - 241, 2003/09

2D-C/C composite is one of the promising materials as a next-generation core material in gas-cooled reactors. Effect of air-oxidation on the thermal diffusivity up to 1673K of the 2D-C/C composite was investigated. The C/C composite specimens for measurement of thermal diffusivity were oxidized from 1 to 11 percent weight loss in air at 823K. Thermal diffusivity at room temperature declined 1020 percent for parallel to lamina direction and 59 percent for that of perpendicular within 11 percent weight loss by oxidation. Thermal diffusivity tended to decrease gradually as the increase of oxidation loss in parallel to lamina, however, it decreased in the beginning of oxidation pretty much and not so changed by further oxidation loss in perpendicular to lamina. Change in thermal conductivity under oxidation condition was also estimated.

Safety evaluation of High Temperature Engineering Test Reactor; Evaluation of graphite oxidation under air ingress and steam ingress accidents

; Ohashi, Kazutaka*; Iyoku, Tatsuo

FAPIG, 0(129), p.13 - 21, 1991/11

no abstracts in English

Air-oxidation of U0 Pellets at 800 and 900

;

Journal of Nuclear Materials, 36(1), p.116 - 119, 1970/00

https://doi.org/10.1016/0022-3115(70)90070-X

no abstracts in English