Event Notification Report for November 22, 2017

LPCI INOPERABILITY DUE TO OVERVOLTAGE RELAY ACTUATION

"On November 22, 2017, at 2043 [CST], Unit I MCC [Motor Control Center] 18/19-5 overvoltage relay target was found actuated and would not reset. MCC 18/19-5 was powered from the normal feed, Bus 19. Bus 19 voltages were verified to be normal. The overvoltage relay actuation would result in MCC 18/19-5 being de-energized in the event of a DBA LOCA [Design Basis Accident Loss of Coolant Accident] in which the 1/2 Emergency Diesel Generator fails to energize Bus 18, therefore rendering both divisions of the Low Pressure Cooling Injection (LPCI) mode of Residual Heat Removal (RHR) system inoperable. Technical Specification 3.5.1 Condition E was entered, requiring restoration of LPCI in 72 hours.

"The overvoltage target was subsequently able to be reset at 2114 [CST], restoring the LPCI function of RHR. Technical Specification 3.5.1 Condition E was exited at that time.

"This event is reportable under 10 CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented fulfillment of a safety function."

The licensee notified the NRC Resident Inspector.

EN Revision Imported Date : 01/16/18

EN Revision Text: LPCI INOPERABILITY DUE TO OVERVOLTAGE RELAY ACTUATION

"On November 22, 2017, at 2043 [CST], Unit I MCC [Motor Control Center] 18/19-5 overvoltage relay target was found actuated and would not reset. MCC 18/19-5 was powered from the normal feed, Bus 19. Bus 19 voltages were verified to be normal. The overvoltage relay actuation would result in MCC 18/19-5 being de-energized in the event of a DBA LOCA [Design Basis Accident Loss of Coolant Accident] in which the 1/2 Emergency Diesel Generator fails to energize Bus 18, therefore rendering both divisions of the Low Pressure Cooling Injection (LPCI) mode of Residual Heat Removal (RHR) system inoperable. Technical Specification 3.5.1 Condition E was entered, requiring restoration of LPCI in 72 hours.

"The overvoltage target was subsequently able to be reset at 2114 [CST], restoring the LPCI function of RHR. Technical Specification 3.5.1 Condition E was exited at that time.

"This event is reportable under 10 CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented fulfillment of a safety function."

The licensee notified the NRC Resident Inspector.


* * * RETRACTION FROM RONALD SNOOK TO STEVEN VITTO ON 01/11/18 AT 1913 EST * * *

"The purpose of this notification today (01/11/18) is to retract the ENS Report made on November 23, 2017 at 0248 hours EST (ENS Report #53089).

"Upon further review, it was determined that the Unit 1 MCC 18/19-5 overvoltage relay target that was found actuated and would initially not reset was caused only by intermittent degraded DC control power. During this event, MCC 18/19-5 remained powered from the normal feed Bus 19, and Bus 19 voltages were verified to be normal.

"It was further determined from plant drawings that under this condition the degraded DC control power to the Unit 1 MCC 18/19-5 overvoltage relay has no impact to the Technical Specification 3.5.1 required capability to auto transfer power from the normal Bus 19 to the alternate Bus 18 should Bus 19 lose power such as during a DBA LOCA. This overvoltage relay was installed in the early 1990's only to support enhanced reliability of the power supply to the LPCI injection valves, and its actuation due to degraded DC control power would not impact the ability to auto transfer to alternate Bus 18. Therefore, both divisions of the Low Pressure Cooling Injection (LPCI) mode of Residual Heat Removal (RHR) system would have remained fully operable under the as-found relay condition, and Technical Specification 3.5.1 Condition E was not required to be entered.

"On December 6, 2017, it was determined that a loose fuse clip terminal had caused the DC control power to the overvoltage relay to become degraded which in turn caused the relay target and its reset to become erratic. This fuse clip terminal was repaired on December 6, 2017. Based on the subsequent reviews of this event, the LPCI system was not required to be declared inoperable in accordance with Technical Specifications 3.5.1 during the period of the MCC 18/19-5 overvoltage relay actuation (i.e., 31 minutes on 11/22/17), and hence was not required to be reported under 10CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented fulfillment of a safety function.

"Therefore, based on this information, ENS Report #53089 is being retracted.

"The NRC Resident Inspector has been notified."

R3DO(Jeffers) has been notified.

ST. LUCIE UNIT 2 UNUSUAL EVENT DUE TO A SMOKE DETECTOR ALARM RECEIVED INSIDE CONTAINMENT

"St. Lucie Unit 2 declared an Unusual Event due to a smoke detector alarm received in the Unit 2 Containment Building that was unable to be confirmed within 15 minutes. A Containment entry is currently being planned to determine the validity of the alarm.

"State and local officials have been notified by the licensee."

The NRC Resident Inspector has been notified.

Notified DHS SWO, FEMA Operations Center, DHS NICC, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).

* * * UPDATE ON 11/22/17 AT 1143 EST FROM JULIUS FLETCHER TO JEFF HERRERA * * *

"Personnel entered Containment to determine conditions and found no evidence of smoke, fire or damage to equipment. Event terminated at 1127 EST 11/22/17."

The NRC Resident Inspector has been notified.

Notified R2DO (Suggs), R2 DRA (Dudes), NRR (Brock), IRD (Gott), and NRR EO (Miller), DHS SWO, FEMA Operations Center, DHS NICC, FEMA NWC (email), DHS Nuclear SSA (email), and FEMA NRCC SASC (email).

AGREEMENT STATE REPORT - RADIOGRAPHY CAMERA MALFUNCTION

The following report was received via e-mail:

"A crew with [Shawcor] experienced a malfunction on the evening of November 21, 2017, with the INC IR-100 exposure device they were using when performing radiographic operations at Ward Petroleum (10404 E. 146th, Thornton, CO).

"Exposure Device: INC IR-100 (s/n 6839)
"Source: INC (s/n T0799) 65 curies

"After completing a radiographic exposure, the crew attempted to crank the source back into the exposure device; however, they were still able to crank the source out even after the button on the exposure device popped up to indicate the source was fully retracted and locked in place. After an attempt to crank the source out and back into the exposure device, the button was still popping up prematurely. Realizing there was a problem with the locking mechanism, the crew ensured their 2 mR/hr boundary was properly established and immediately contacted the Site RSO/Branch Manager. The crew maintained visual surveillance of the area until [the RSO], along with [the Assistant Site RSO], arrived at the jobsite.

"When [the RSO and Assistant Site RSO] arrived at the jobsite, they also ensured the 2 mR/hr boundary was properly established and began to assess the situation. There was no visible damage to any associated equipment (guide tube, crank assembly, etc.). They attempted several times to crank the source out and back into the fully shielded position; each time the button popped up prematurely even though the source was not locked into the exposure device. While holding down the button on the exposure device, [the RSO] was able to crank the source back in and upon releasing the button, the source locked in place. Surveys were completed to ensure the source was fully shielded.

"At no time during the incident did any crew member's dosimeter go off-scale and there was no threat of overexposure at any time to our company's employees, nor un-monitored workers. All personnel involved were wearing and utilizing proper radiation detection equipment, including OSL [Optically Stimulated Luminescent] badges, pocket dosimeters, alarming rate meters, and they were properly utilizing survey meters.

"The INC exposure device will be sent back to the manufacturer for maintenance and repair, if necessary."

PART 21 - DEFECT IN THERMOSTATIC VALVE ASSEMBLIES

The following information was excerpted from a facsimile received from Engine Systems, Inc.:

"Two thermostatic valve assemblies were supplied by [Engine Systems, Inc.] ESI that were found to have retaining straps, subcomponents of the internal thermostatic element, detached from the correct position. For each valve assembly, one of the thermostatic elements (the centrally located element) contained this defect. The straps are used in conjunction with a spring to retain the element in a closed position. As the temperature of the sensed fluid increases, a temperature sensitive wax expands to open the element while acting against the spring. As the temperature of the fluid decreases, the wax contracts and the spring returns the element to its closed position. Absence or failure of the straps would prevent proper operation of the element.

"The thermostatic valve assembly is used on an emergency diesel generator [EDG] set to regulate the temperature of lubricating oil (other EDGs use this same type of valve for jacket water temperature regulation). If one of the elements within the assembly were to fail, as is the case with a missing strap, regulating capacity of the thermostatic valve could be affected. However, the failure mode in the case of missing straps is in the open position (element does not return closed) and the remaining eight elements would compensate by closing to regulate the fluid temperature. More importantly, detached retaining straps could migrate to other components in the lube oil system. Acting as foreign material, the straps could adversely affect the ability of these critical components to perform their safety-related function within the emergency diesel generator's lube oil piping. The foreign material aspect of this defect makes it a reportable issue.

"Information of such defect or failure to comply was obtained on November 22, 2017.

"This issue is an isolated incident affecting two thermostatic valves supplied to one nuclear plant [DC Cook]. The nuclear plant detected the issue during inspection and returned the assemblies to ESI. No further action is required on the part of DC Cook.

"ESI's investigation revealed that this issue was induced by a test technician who, in an effort to minimize the amount of test fluid remaining in the assembly after pressure testing, manually actuated the center thermostatic element (there are 9 total elements) to drain a small pocket of residual fluid. This effort to prevent the formation of oxidation had an unintended consequence and resulted in a more serious issue. Though this is an isolated incident as it pertains to items supplied from ESI, this same model thermostatic valve assembly is used extensively on EDGs in the nuclear industry. Those customers that perform valve maintenance, including thermostatic element replacement, should be aware of the possibility of the straps becoming detached if care is not taken."

If you have any questions, you may call:

Tom Horner
Quality Assurance Manager
Tel: (252) 977-2720

ESI Report ID: 10CFR21-0120, Rev. 0, dated 01/05/18