Event Notification Report for March 20, 2017

HISTORICAL EVENT RELATED TO PAST OPERABILITY

"On February 3, 2017, Prairie Island staff performed maintenance on the transom above Battery Room Door 225. This activity resulted in the transom being unlatched for approximately five minutes. On February 6, 2017, a question from the NRC Resident Inspector resulted in an evaluation of this condition for past operability. On March 20, 2017, the past operability evaluation of Door 225 concluded that, in the event of a postulated HELB [High Energy Line Break], the transom being unlatched during the five minute maintenance period resulted in the inoperability of multiple systems in the Unit 1 and Unit 2 battery, auxiliary feedwater, and Unit 1 safeguards bus rooms that would be required to mitigate the postulated HELB.

"The loss of safety functions required to mitigate the postulated HELB make the condition reportable under 50.72(b)(3)(ii) for an unanalyzed condition that significantly degrades plant safety.

"Unlatching the transom above the Battery Room Door creates an opening not accounted for in design bases documents. This occurred due to an improperly prepared work permit. Corrective actions are in place to preclude recurrence."

The licensee informed the NRC Resident Inspector.

* * * RETRACTION FROM MARK LOOSBROCK TO JEFF ROTTON AT 1559 EDT ON 04/10/2017 * * *

"Further analysis determined that an unlatched transom would result in a relative humidity of 100 percent in 11 Battery Room for about 10 minutes following a postulated HELB. Since the equipment in the Battery Rooms is not qualified for a harsh environment, the components in 11 Battery Room would have been inoperable. Temperature and relative humidity in the other Battery Rooms, Auxiliary Feedwater Rooms, and the Unit 1 Safeguards Bus Rooms would have remained within the allowable limits.

"Therefore, for the five minutes the strike was removed from the transom, only equipment in 11 Battery Room and supported A Train components would have been inoperable. This event was not an Unanalyzed Condition that significantly degraded plant safety, under 10 CFR 50.72(b)(3)(ii), as no safety function would have been lost."

The licensee notified the NRC Resident Inspector.

Notified R3DO (Skokowski).

MANUAL SCRAM DUE TO PRESSURE OSCILLATIONS

"On March 20, 2017 at 0227, Nine Mile Point Unit1 was manually scrammed due to pressure oscillations. The Unit was offline and reactor shutdown was in-progress at the time of the scram. The scram was inserted at approximately 4% reactor power when pressure oscillations occurred exceeding the procedurally required limit for pressure oscillations. The cause of the scram was due to Operators manually inserting the scram. The cause of the pressure oscillations is being investigated."

The licensee notified the NRC Resident Inspector.

Notified the R1DO (Gray).

MANUAL REACTOR TRIP AS A RESULT OF SECONDARY PLANT TRANSIENT

"On March 20, 2017 at 0813 EDT, Watts Bar Nuclear Plant (WBN) Unit 2 operations personnel manually tripped the plant from approximately 91 percent power based on lowering steam generator levels. Prior to the plant trip, the 2A Hotwell pump tripped at 0758 EDT and the 2C Condensate Booster Pump subsequently tripped at 0802 EDT. Operations personnel commenced to lower plant power after the 2A Hotwell pump trip in an attempt to maintain steam generator levels, but were unable to recover level and manually tripped the unit.

"All control rods fully inserted and all automatically actuated safety related equipment operated as designed. At 0905 EDT, operations personnel exited the emergency operating instructions after the plant was stabilized. The cause of the event is under investigation.

"This event is reportable to the NRC within four hours under 10 CFR 50.72(b)(2)(iv)(B) as a result of the actuation of the Reactor Protection System and in eight hours under 10 CFR 50.72(b)(3)(iv)(A) as a result of actuation of the Auxiliary Feedwater system.

"The licensee notified the NRC Resident Inspector."

AGREEMENT STATE REPORT - DAMAGED TROXLER GAUGE

The following report was received from the State of Florida Bureau of Radiation Control via email:

"[The licensee] called to inform the BRC [Bureau of Radiation Control] that a Troxler gauge, Model 3430, in use at a construction site on Midway Rd. in Ft. Pierce had been run over by a pick up truck. The gauge was not in the transport case. The source rod was retracted. The outer plastic case and the screen are damaged. Reading of unit taken with a TroxAlert, Model 3105B indicated source / shielding is intact. All reading around the meter were normal background. Gauge will be taken to Atlantic Drill Supply, Rivera Beach, FL for repairs.

"Florida Incident Number: FL17-089"

UNUSUAL EVENT DECLARED FOR FIRE ALARM IN CONTAINMENT

"At 1620 [CDT], an unusual event was declared due to a smoke detector alarm in Unit 1 containment. [There were] no indications of any other detector alarms, no abnormal equipment indications, and containment parameters are normal (temperature, humidity).

"At 1631 [CDT], visual inspection [of the] 66 ft. hatch indicated no smoke or abnormal smell.

"At 1640 [CDT], local inspection of Unit 1 containment verified no fire or hot spots."

The licensee has notified the NRC Resident Inspector.

Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via E-mail.

* * * UPDATE FROM RYAN RODE TO DONG PARK AT 2208 EDT ON 3/20/2017 * * *

"Event transmitted under ENS # 52627 is terminated at 2022 [CDT on] 3/20/17."

The NRC Resident Inspector has been notified.

Notified R3DO (Orlikowski), NRR EO (Miller), and IRD (Stapleton). Notified DHS SWO, FEMA Ops Center, DHS NICC. Notified FEMA National Watch and Nuclear SSA via E-mail.

60-DAY OPTIONAL TELEPHONE NOTIFICATION FOR AN INVALID HIGH PRESSURE COOLANT INJECTION SYSTEM ACTUATION

"Pursuant to 50.73(a)(1) the following information is provided as a sixty (60) day telephone notification to the NRC. This notification, reported under 50.73(a)(2)(iv), is being provided in lieu of the submittal of a written LER to report a condition that resulted in an invalid actuation of the high pressure coolant injection (HPCI). At Nine Mile Point Unit 1, HPCI is a flow control mode of the normal feedwater system and is not an emergency core cooling system.

"On March 20, 2017 at 0216 EDT, Nine Mile Point Unit 1 reactor shutdown was in progress. The Unit 1 generator was off line, the 100 percent capacity 13 feedwater pump (13 FW) was removed from service, and the Unit 1 main turbine had been tripped appropriately per procedure while entering a planned refueling outage. At approximately 4 percent reactor power, a clearance tagging evolution was in progress to support shutdown activities. During this evolution a tag was applied that caused an unanticipated activation of a lock out (86) relay due to the failure to bypass this relay prior to the tag application. This 86 relay activation in turn resulted in a generator trip signal followed by a turbine trip signal. With the generator off line and the turbine already tripped there was no actual change in any plant parameter or condition that would have created a valid turbine trip signal and the associated HPCI initiation.

"The plant configuration at the time of the main turbine trip signal had one motor operated feedwater pump, 12 Feedwater Pump (12 FW), in service and providing normal reactor level control. HPCI did initiate as designed upon receiving the generator and main turbine trip signals caused by the activation of the 86 relay. The 12 FW pump, which was providing normal reactor level control, transitioned the level control from automatic mode into HPCI mode of operation. Per design, the 11 FW pump automatically started but was not required to and did not flow water since 12 FW pump was in operation. The 11 FW pump was subsequently secured by operations. At no point in time did the HPCI system receive a valid initiation signal (due to high DW pressure, low reactor water level, or a valid turbine trip with loss of the turbine driven 13 FW pump). Operators reset HPCI and returned water level to Automatic Control at 0218.

"The Licensee has notified the NRC Resident Inspector."