April 18, 1989

HFIR resumes production after two-year pause for safety

In November 1986 tests on irradiation surveillance specimens indicated that the reactor vessel was being embrittled by neutron irradiation at a rate faster than predicted. The HFIR was shut down to allow for extensive reviews and evaluation of the operation of this facility.

Two years and five months later, after thorough reevaluation, modifications to extend the life of the plant while protecting the integrity of the pressure vessel, and upgrades to management practices, the reactor was restarted. Coincident with physical and procedural improvements were renewed training, safety analysis, and quality assurance activities. Documents were updated, and new ones were generated where necessary. Technical specifications were amended and reformatted to keep abreast of the design changes as they were accepted by DOE. Not only were the primary coolant pressure and core power reduced to preserve vessel integrity while maintaining thermal margins, but long-term commitments were made for technological and procedural upgrades.

After a thorough review of many aspects of HFIR operation, the reactor was restarted for fuel cycle 288 on April 18, 1989, to operate initially at very low power levels (8.5 MW) until all operating crews were fully trained and it was possible to operate continuously at higher power.