Safety Characteristics of GTHTR and Safety Demonstration Test Program Using HTTR

JAEA has long been designing series of Gas Turbine High Temperature Reactor (GTHTR) based on advanced HTGR technologies developed through the construction and operation of the High Temperature Engineering Test Reactor (HTTR). Inherent safety characteristics of the GTHTR keep the reactor safe and stable condition with no risk of core meltdown even in the worst case accidents such as a primary pipe rupture, station blackout, etc. In addition to design studies of the GTHTR, JAEA conducted or will conduct several safety demonstration tests using the HTTR to examine the reactor transient behavior during the worst case accident and to validate and verify analytical tools of the design for an High Temperature Gas-cooled Reactor (HTGR). These tests are not only valuable to develop design tools, but also are effective to convince safety authority and average people that the GTHTR is a safe and reliable system to be acceptable after the Higashi-Nihon earthquake and to be deployed in 2020s. This paper describes safety design of the GTHTR and a safety demonstration test program of the HTTR. Also, it presents the results of safety evaluation during a primary pipe rupture and the following station blackout. The evaluation results revealed that the maximum fuel temperature is kept under the allowable limit and fission products are safety contained in the fuel due to salient safety characteristics.