This is a non-emergency notification. At 1804 PST on December 17, 2012, Diablo Canyon Unit 1 experienced a loss of plant vent continuous radiation monitors (
RM) and redundant monitors 14/14R, 24/24R, 28/28R and 87. These radiation monitors are credited for Emergency Action Level (
EAL) classification in the Diablo Canyon
Emergency Plan. This event is reportable per
10 CFR 50.72(b)(3)(xiii) as described in
NUREG-1022, Rev. 2. Compensatory measures of periodic sampling have been established in accordance with plant equipment control guidelines. Event classification can be performed by means of the sampling in accordance with plant procedures. Additionally, continuous radiation monitoring of the plant vent remains via high range radiation monitor RM-29.
The cause of the loss of radiation monitors is not known at this time.
This condition does not affect the health and safety of the public or the operation of the facility.
The NRC Resident Inspector was informed.
- * * UPDATE AT 0948 EST ON 12/18/12 FROM DAVE GOUVEIA TO HUFFMAN * * *
The licensee determined that the flow element on the sampling pump for the radiation monitors had failed. At 0630 EST, the condition was repaired and the radiation monitors returned to service.
R4DO (Whitten) notified.
