Event Notification Report for March 05, 2010

SPECIFIED SYSTEM ACTUATION - FEEDWATER ISOLATION DUE TO HIGH STEAM GENERATOR WATER LEVEL

"A Turbine trip and Feedwater Isolation Signal was generated as a result of high level in 'A' Steam Generator. At approximately 0007 CST, a turbine trip and Feedwater Isolation Signal was generated when the level in the 'A' Steam Generator exceeded the initiation set point of 78%. Steam Generator level returned below the initiation setpoint at approximately 0008 CST. Steam Generator 'A' high level resulted from swell of the Steam Generator after opening the 'A' Main Steam Isolation Valve. Level was approximately 50% prior to the event and returned to approximately 50% within one minute.

"The turbine was already in the tripped condition due to the plant trip that occurred at 1458 CST on 03/02/2010 (Reference EN# 45739).

"Steam Generators are being fed with the motor driven startup Feedwater pump. Decay heat removal is via the Steam Generator Atmospheric Relief Valves and steam dumps. The plant is in Mode 4 with Reactor Coolant System pressure at approximately 500 psig and temperature at approximately 332 degrees F.


"Two Main Feedwater isolation valves did not fully close but the actuators were being supplied with auxiliary medium (air) at the time of the actuation. Feedwater isolation valves are not required to be operable in Mode 4."

The licensee will notify the NRC Resident Inspector.

* * * RETRACTION FROM RICK HUBBARD TO PETE SNYDER AT 1456 ON 4/29/2010 * * *

"This event (Event Number 45745) is being retracted. A valid actuation of any systems listed in paragraph 50.72 (b)(3)(iv)(B) did not occur. The plant was in Mode 4 and neither a reactor trip nor an auxiliary feedwater system actuation signal occurred. Additional evaluation determined that the turbine trip and feedwater isolation signal are a function of the ESFAS [Engineered Safety Features Actuation System] instrumentation and does not result in an actuation of the RPS [Reactor Protection System] or other systems listed in paragraph 50.72 (b)(3)(iv)(B)."

The licensee notified the NRC Resident Inspector.

Notified R4DO(Clark).

UNANALYZED CONDITION - STEAM SUPPLY VALVE CREDITED AS CLOSED IN FSAR ANALYSIS IS NORMALLY OPEN DURING OPERATIONS

"Valve FBV0147, Boric Acid Batch Tank Auxiliary Steam Supply Isolation Valve, is credited with being closed in the Callaway FSAR. This eliminated the need to analyze lines FB-081-HBD and FB-082-HBD for high energy line breaks (HELB). However, FBV0147 was found to be kept normally open to allow steam service for the boric acid batching tank. This is contrary to the normal position assumed in the FSAR and HELB analyses.

"With valve FBV0147 open, the lines must considered high energy lines. The lines are in the auxiliary building and they traverse rooms containing several components including the flow transmitters for Residual Heat Removal (RHR) to train `A' accumulator injection supply header, RHR train `A' and 'B' SIS hot leg recirculation supply header, and several safety related auxiliary feedwater components. These instruments are used to provide indications during post-accident conditions. This configuration is therefore outside of current HELB analysis and potentially represents a condition that significantly degrades plant safety.

"The condition was identified to Operations at 0740. Valve FBV0147 was closed at 0810. At 1325 CST, the issue was determined to be reportable.

"The NRC Resident Inspector has been notified."

* * * RETRACTION AT 1557 EDT ON 5/3/10 FROM HURT TO HUFFMAN * * *

"On 03/05/2010, EN #45747 provided notification that valve FBV0147 was found to be kept normally open to allow steam service for the boric acid hatching tank. This configuration was not consistent with the normal position assumed in the FSAR and HELB analyses.

"An engineering evaluation was subsequently performed for the auxiliary steam inlet and outlet piping for the boric acid batching tank. This valuation identified four postulated break locations which have all been analyzed. The analyses determined that all safety-related components in the affected rooms would be able to perform their safety functions in the event of a line break. Pipe whip, jet impingement, compartment temperature and over pressurization, flooding, and internal missiles resulting from a postulated line break would not prevent any safety-related equipment from performing its design function.

"As supported by this evaluation, this condition does not meet the criteria for an unanalyzed condition that significantly degrades plant safety as stated in 10 CFR 50.72(b)(3)(ii)(B). Therefore, the notification made on 03/05/2010 is hereby retracted.

"The NRC Resident Inspector will be notified."

R4DO (Farnholtz) notified.

INVALID ISOLATION SIGNAL CAUSED MSIV'S TO CLOSE

"This telephone notification is provided in accordance with 10 CFR 50.73(a)(1) to report an invalid actuation reportable under 10 CFR 50.73(a)(2)(iv)(A).

"On March 5, 2010, at 0539 hours, during the Unit 1 refueling outage (L1R13), the inboard and outboard Main Steam Isolation Valves (MSIVs) closed as a result of an invalid partial Group 1 PCIS (Primary Containment Isolation System) isolation signal generated during the performance of station surveillance LOS-TG-SR2 'Operability of Main Turbine Valves and Controls Following an Extended Outage.'

"Investigation revealed that during the resetting of the main turbine, the Group 1 PCIS logic received a signal that one of the Turbine Stop Valves (TSVs) was open. This caused the logic for Group 1 PCIS logic to be made up and the MSIVs to shut. Review of the data indicates that at no time did any of the TSVs open during the testing. This issue occurred as a result of the vibration seen by the relays in the trip logic during the resetting of the main turbine.

"The apparent cause of this event was attributed to a lack of questioning attitude during testing. The surveillance has multiple actions for cycling all the turbine valves, as well as performing various trips and resets of the main turbine. The surveillance has a prerequisite to ensure during performance of the various sections, that the MSIVs are shut or jumpers are installed to prevent an inadvertent closure of the MSIVs should the TSVs be cycled. The operating crew had concluded that the section of the procedure they were performing did not require the MSIVs to be shut or the jumpers to be installed.

"When the turbine was reset, the Reactor Protection System (RPS) Channels A1 and B2 actuated. Based upon these actuations, plant response to the partial Group 1 PCIS isolation signal was as expected. This actuation was invalid since the conditions required to bypass the low condenser vacuum Group 1 PCIS isolation were all met. With the mode switch not in run, the condenser low vacuum bypass keys in bypass and the main stop valves not full open, the Group 1 PCIS isolation is bypassed. These conditions were all met when the partial Group 1 PCIS isolation was received. The TSVs remained closed as indicated on the Digital Electro-Hydraulic Control (DEHC) system.

"Corrective actions include enhancements to the surveillance procedure and preparation of a case study on the circumstances, which led to this event. [Corrective actions also include presentation] to all operating crews in LORT [Licensee Operations Requalification Training] Cycle 10-4 and various site training advisory and curriculum review committees."

The licensee has notified the NRC Resident Inspector.