Active chemistry control for coolant helium applying high-temperature gas-cooled reactors

Nariaki Sakaba, Shimpei Hamamoto, Yoichi Takeda

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

Lifetime extension of high-temperature equipment such as the intermediate heat exchanger of high-temperature gas-cooled reactors (HTGRs) is important from the economical point of view. Since the replacing cost will cause the increasing of the running cost, it is important to reduce replacing times of the high-cost primary equipment during assumed reactor lifetime. In the past, helium chemistry has been controlled by the passive chemistry control technology in which chemical impurity in the coolant helium is removed as low concentration as possible, as does Japan's HTTR. Although the lifetime of high- temperature equipment almost depends upon the chemistry conditions in the coolant helium, it is necessary to establish an active chemistry control technology to maintain adequate chemical conditions. In this study, carbon deposition which could occur at the surface of the heat transfer tubes of the intermediate heat exchanger and decarburization of the high-temperature material of Hastelloy XR used at the heat transfer tubes were evaluated by referring the actual chemistry data obtained by the HTTR. The chemical equilibrium study contributed to clarify the algorism of the chemistry behaviours to be controlled. The created algorism is planned to be added to the instrumentation system of the helium purification systems. In addition, the chemical composition to be maintained during the reactor operation was proposed by evaluating not only core graphite oxidation but also carbon deposition and decarburization. It was identified when the chemical composition could not keep adequately, injection of 10 ppm carbon monoxide could effcctivcly control the chemical composition to the designated stable area where the high-temperature materials could keep their structural integrity beyond the assumed duration. The proposed active chemistry control technology is expected to contribute economically to the purification systems of the future very high-temperature reactors.

Original languageEnglish
Title of host publication2008 Proceedings of the 4th International Topical Meeting on High Temperature Reactor Technology, HTR 2008
Pages625-631
Number of pages7
Publication statusPublished - 2009 Oct 16
Event2008 4th International Topical Meeting on High Temperature Reactor Technology, HTR 2008 - Washington, DC, United States
Duration: 2008 Sep 282008 Oct 1

Publication series

Name2008 Proceedings of the 4th International Topical Meeting on High Temperature Reactor Technology, HTR 2008
Volume1

Other

Other2008 4th International Topical Meeting on High Temperature Reactor Technology, HTR 2008
CountryUnited States
CityWashington, DC
Period08/9/2808/10/1

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Nuclear Energy and Engineering

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