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At 1734 on 2/7/2005, received an Area Radiation Monitor alarm in the reactor building basement airlock area at approximately 75Mr/hr. The valid alarm caused entry into EOP flowcharts for High Radiation in the Secondary Containment. Check of the relay room monitor showed 100 Mr/hr. Investigation showed that a failed open main steam line drain valve combined with placing hydrogen water chemistry in service caused the increasing radiation levels. A downstream steam line drain isolation valve was closed to isolate the steam flow path past the monitor. Hydrogen Water Chemistry injection rate was lowered. The Rad levels returned to about 4 Mr/hr (normal levels) following valve closure (at 1745). The EOPs were exited at 1755. After review of the event it was determined that an unusual event should have been entered at the time of the EOP entry (EAL AU2, Unexpected Increase of Plant Radiation Levels), 1734 and exited at 1745 when area radiation levels returned to normal values. This is an after the fact notification of a missed emergency classification. The NRC Resident Inspector was notified.

• * * UPDATE ON 2/10/05 AT 1907 HRS. EST BY CROUCH * * *

This event notification reporting criteria has been changed to comply with the guidance provided in NUREG-1022, Rev. 2, "Event Reporting Guidelines 10CFR 50.72 and 50.73". There is specific discussion that states (in part) that if a licensee discovers that a condition existed which met the emergency plan criteria but no emergency was declared and the basis for the emergency class no longer exists at the time of discovery, an actual declaration of the emergency class is not necessary. An ENS notification of the missed classification is an acceptable alternative. The Headquarters Operations Officer notified R3DO (Duncan).