Fig. 5-6 Overall view of HENDEL

Fig. 5-7 Relationship between fuel rod to helium gas heat transfer coefficients and helium gas flow rates The fuel rod heat transfer coefficients were demonstrated to be higher than those used in a previous design; therefore, the fuel temperature could not increase to the critical temperature.

This picture, 10KB

Fig. 5-8 Temperature distributions in core-bottom structure and in pressure vessel (Helium gas temperature 1000 degrees cent.) The temperatures of the components consisting of the core-bottom structure and the pressure vessel were demonstrated to be maintained lower than the design temperatures of these components.

The Helium Engineering Demonstration Loop (HENDEL) is the largest helium gas loop in the world. It was constructed to confirm reactor safety and to verify the original design and fabrication technologies of the High-Temperature Engineering Test Reactor (HTTR): the first high-temperature, gas-cooled reactor in Japan. Full-scale models of fuel elements and the core-bottom structure consisting of the HTTR core are installed in HENDEL. High-pressure helium gas (up to 4 MPa) electrically heated up to 1000 degrees cent. by is supplied to these components to investigate the heat transfer performance of the fuel elements and temperature distributions in the core-bottom structure. The heat transfer coefficients of fuel rods in the fuel elements were demonstrated to be higher than those used in a previous design. The temperatures of components of the core-bottom structure and the pressure vessel were shown to be lower than the design temperatures of these components. These results confirmed the safety performance of the HTTR. In addition, fabrication and operational technologies for the HTTR have been improved through the construction and operation of HENDEL.

Reference Y. Miyamoto, et al., Demonstration Tests for HTGR Fuel Elements and Core Components with Test Sections in HENDEL, JAERI 1333 (1995).

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