HTTR delays

1 February 1998

First criticality of the High Temperature Test Reactor, originally scheduled for December 1997, has been put back to June 1998. During this time JAERI (Japan Atomic Energy Research Institute) will make needed improvements to some systems, eg modifications to reduce noise in the I&C systems and improvements in the helium purification system to ensure that design operating temperatures can be achieved.

The Nuclear Safety Committee has also asked JAERI to check six points:

• Procedures JAERI has in place for technology exchanges with other organisations concerning operational aspects of high temperature gas-cooled reactors to ensure the continuity of HTTR technology.

• Procedures for incorporating experience which has been obtained in Japan and other countries since the construction of the HTTR was approved.

• Detailed schedules for testing and operation from initial criticality up to the first reloading.

• Procedures for evaluating reactivity measurements and their reliability when the reactor is nearly critical and during heat-up.

• Criteria for fuel damage and the procedures for detecting and replacing damaged fuel.

• Methods of analysing helium leakage and defining the status of a helium leak.

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