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JAEA starts test series to demonstrate safety characteristics of HTGR under loss of core cooling transients
–First test of the loss of core flow tests has been finished–

Dec. 22 , 2010

JAEA has started the test series to demonstrate safety characteristics of high temperature gas-cooled reactor (HTGR) using HTTR(Fig.1). The core flow rate of the HTTR stopped to decrease core cooling capacity remarkably by stopping all primary gas circulator under 30% of reactor power (9MW) on December 21, 2010. The reactor power decrease rapidly without abnormal fuel temperature rise and the reactor was kept steady state. The test is called “loss of core flow test”. The test was the first test of the test series.

HTGR core has large heat capacity due to large amount of graphite in the core. HTGRs, therefore, has inherent safety characteristics that is slow temperature change and no fuel failure capability (core melt) at accidents because of large heat capacity of the core.

JAEA will carry out the loss of core flow tests with higher reactor power. Also, tests to stopping residual heat removal system of a vessel cooling system with stopping all primary gas circulator. The tests are called “loss of core cooling tests”. The loss of core cooling tests is the first test in the world.

The superior safety characteristics of HTGR will be demonstrated by the test series using the HTTR. It will contribute simplified design of engineered safety features and improvement of the economy of future HTGRs(Fig.2). Also, the test series will contribute HTGR development program in Kazakhstan, Next Generation Nuclear Plant (NGNP) in United States.

Figure1    High Temperature Engineering Test Reactor (HTTR)

Figure2    Future research and development on HTGR

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