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At 0453 CST on 01/02/2006, the Plant Shift Superintendent (PSS) was notified that steam was observed leaking from the C-337A Position 1 West Autoclave. A 14 ton cylinder containing 0.711 % U235 assay uranium hexafluoride had been heating (TSR (Technical Safety Requirement) Mode 5) for approximately 5 minutes when the leak was observed. The autoclave pressure containment boundary is a TSR system required to be operable per TSR 2.2.3.1, 'Autoclave High Pressure Isolation System (HPIS),' when the autoclave is in Mode 5. The autoclave was placed in Mode 2, 'Autoclave Out-of-Service' in accordance with LCO Required Actions 2.2.3.1.C. This event is reportable as a 24 hour event in accordance with 10CFR 76.120(c)(2)(i). This is an event in which equipment is disabled or fails to function as designed when: a.) the equipment is required by a TSR to prevent releases, prevent exposures to radiation and radioactive materials exceeding specified limits, mitigate the consequences of an accident, or restore this facility to a pre-established safe condition after an accident; b.) the equipment is required by a TSR to be available and operable and either should have been operating or should have operated on demand, and c.) no redundant equipment is available and operable to perform the required safety function. The licensee noted that after steam was turned off to the autoclave, an inspection of the o-ring sealing surfaces did not identify any problems. No other sources of a steam leak could be found in the autoclave. The HPSI was declared inoperable due to a possible head-to-shell leak. The licensee will need to wait for a five day cool down time for the cylinder in the autoclave before it can be removed. Once the cylinder is removed, the autoclave can be re-pressurized in an attempt to determine the leak location. The NRC Senior Resident Inspector and DOE have been notified of this event.

• * * UPDATE AT 15:03 EST ON 01/18/06 FROM SKAGGS TO KNOKE * * *

This notification is being retracted. On January 11, 2006, the 1 west autoclave was subjected to an autoclave pressure decay test. The autoclave passed the test on both the inner and outer containment valves. This proved that the steam leak reported by operators was not from a breach of the autoclave containment boundary, and that the AHPIS was performing as designed during the heat cycle initiated on January 2, 2006. Following the pressure decay test, steam was valved into the autoclave in an effort to find the steam leak. Steam vapor was seen under the autoclave at the location reported by operators on January 2, 2006. The steam vapor was discovered to be coming from a condensate blow-down hose that had moved away from the condensate drain housing allowing steam vapor to escape. No other leaks were noted. The successful autoclave pressure decay test provides evidence that the AHPIS was operable and available while the autoclave was in TSR Mode 5 on January 2, 2006, and thus the reporting criteria was not met. The NRC Senior Resident Inspector for PGDP has been notified of this retraction. Notified R2DO (Ogle) and NMSS Daytime EO (Morell)