05000390/LER-2012-003

LER-2012-003, 1 OF 5

Watts Bar Nuclear Plant, Unit 1
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3902012003R01 - NRC Website

FACILITY NAME

Tommy Morgan, Watts Bar Site Licensing Engineer TELEPHONE NUMBER (Include Area Code) 423-365-1401

14. SUPPLEMENTAL REPORT EXPECTED

YES (If yes, complete 15. EXPECTED SUBMISSION DATE) El NO

DATE

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) On September 21, 2009, Watts Bar Nuclear Plant Unit 1 (WBN) entered Mode 4 as part of the Cycle 9 refueling outage (RFO). When Mode 4 was entered, two Safety Injection (SI) pumps and more than one Centrifugal Charging Pump (CCP) were capable of injecting into the Reactor Coolant System (RCS). Technical Specification (TS) 3.4.12, "Cold Overpressure Mitigation System (COMS)," requires that a maximum of one CCP and no SI pumps be capable of injecting into the RCS when in Modes 4, 5, or 6 (with the reactor head on). As a result, Limiting Condition for Operation (LCO) 3.4.12 was not met and the applicable Required Actions were not taken within their associated Completion Times. Therefore, WBN was in a condition prohibited by the TSs.

A review of previous operating data revealed this condition also existed on April 4, 2011, when WBN entered Mode 4 as a part of the Cycle 10 RFO.

The cause of this event was that personnel were ineffective at the use of human performance tools. Specifically, personnel were ineffective at self checking to ensure all required procedures were identified during an impact review for a License Amendment request.

F. PLANT CONDITIONS

Watts Bar Nuclear Plant Unit 1 (WBN) was in Mode 4 at 0% percent rated thermal power (RTP).

IL DESCRIPTION OF EVENT

A. Event

Technical Specification (TS) 3.4.12, "Cold Overpressure Mitigation System (COMS)," controls Reactor Coolant System (RCS) [EllS Code AB] pressure at low temperatures so the integrity of the reactor coolant pressure boundary is not compromised by violating the pressure and temperature limits. Limiting Condition for Operation (LCO) for TS 3.4.12 requires that COMS must be Operable with a maximum of one charging pump (CCP) [EMS Code P] and no safety injection (SI) pumps [EMS Code P] capable of injecting into the RCS when in Modes 4, 5, and Mode 6 (when the reactor vessel head is on).

On September 21, 2009, WBN entered Mode 4 at 0420 Eastern Daylight Time (EDT) as part of the Cycle 9 refueling outage (RFO). When Mode 4 was entered, two SI pumps and more than one CCP were capable of injecting into the RCS. As a result, LCO 3.4.12 was not met and the applicable Required Actions were not taken within their associated Completion Times. Therefore, WBN was in a condition prohibited by the Technical Specifications, which is reportable under 10 CFR 50.73(a)(2)(i)(B).

A review of previous operating data revealed this condition also existed on April 4, 2011, when WBN entered Mode 4 at 0454 EDT as a part of the Cycle 10 RFO.

B. Inoperable Structures, Components, or Systems that Contributed to the Event None C. Dates and Approximate Times of Major Occurrences Date Time Event (EDT) March 3, 2005 N/A NRC Issuance of Amendment 55 Regarding Mode Change Limitations Using the Consolidated Line Item Improvement Process September 21, 2009 0420 LCO 3.4.12 not met due to two SI pumps and more than one CCP being capable of injecting into the RCS while in Mode 4 April 4, 2011 1454 LCO 3.4.12 not met due to two SI pumps and more than one CCP being capable of injecting into the RCS while in Mode 4 August 10, 2012 1404 TVA discovered that WBN procedure GO-6, "Unit Shutdown From Hot Standby to Cold Shutdown," was not consistent with TS 3.4.12, and therefore LCO 3.4.12 was not met and the applicable Required Actions were not taken within their associated Completion Times on September 21, 2009 and April 4, 2011 IL DESCRIPTION OF EVENT (continued)

D. Other Systems or Secondary Functions Affected

None

E. Method of Discovery

During a review of an Operations procedure against TS 3.4.12, the WBN Operations Department identified that a possible discrepancy existed between TS 3.4.12 and the Operations procedure.

On August 10, 2012, the WBN Operations and Licensing Departments concluded that the Operations procedure was not consistent with TS 3.4.12, resulting in WBN not meeting LCO 3.4.12 and the applicable Required Actions not being taken within their associated Completion Times on September 21, 2009 and April 4, 2011.

F. Operator Actions

None

G. Safety System Responses

None

CAUSE OF EVENT

The cause of this event was the operator assigned to conduct the impact review for the License Amendment request associated with WBN TS Amendment 55 failed to identify all impacted procedures.

This indicates a human performance failure associated with self checking.

The original causal analysis concluded that an increase in qualifications would resolve this issue. Upon further review, it was determined that a Senior Reactor Operator (SRO) License would not ensure that impacted procedures are appropriately identified and dispositioned.

The unidentified impact to the Operations procedure resulted in WBN not meeting LCO 3.4.12 and the applicable Required Actions not being taken within their associated Completion Times on September 21, 2009 and April 4, 2011.

IV. ANALYSIS OF THE EVENT

A WBN Operations procedure provided actions to perform a unit shutdown from Hot Standby at normal operating temperature and pressure to Cold Shutdown, including the transition from Mode 3 to Mode 4.

This procedure allowed up to four hours to secure both SI pumps and one CCP after entering Mode 4.

This four hour allowance was consistent with TS 3.4.12 prior to the implementation of WBN TS Amendment 55, but Amendment 55 removed the four hour allowance. During the implementation of WBN TS Amendment 55, the impact on the Operations procedure was not identified, and as a result, LCO 3.4.12 was not met and the applicable Required Actions were not taken within their associated Completion Times on September 21, 2009, and April 4, 2011, when transitioning from Mode 3 to Mode 4 for scheduled RFOs.

V. ASSESSMENT OF SAFETY CONSEQUENCES

There were no safety consequences resulting from this event. The September 21, 2009, and April 4, 2011, events did not affect systems or components required to shutdown and maintain safe shutdown conditions, remove residual heat, and mitigate the consequences of an accident. In addition, there were no instances of RCS pressure rise which would have challenged the RCS pressure boundary. Therefore, there was no impact on the health and safety of the public.

VI. CORRECTIVE ACTIONS

A. Immediate Corrective Actions

WBN procedure GO-6, "Unit Shutdown From Hot Standby to Cold Shutdown," was revised on August 16, 2012, to be consistent with TS 3.4.12.

B. Corrective Actions to Prevent Recurrence

This event represents a latent human performance error. As such, there is no direct corrective actions associated with the human performance issues associated with the apparent cause.

However, at the time of the event, human performance guidance was limited to a Business Practice Handbook Appendix (BP-253). Since that time, the Human Performance Program has been developed into a Nuclear Power Group Standard Program and Practice Procedure, NPG- SPP-22.202, Human Performance Tools. This procedure has listing of operator tools, practices, and procedures. Therefore, the likelihood or a human error has been significantly reduced and no further actions are required.

A. Failed Components

None B. Previous LERs on Similar Events where LCO 3.4.12 was not met because a SI pump was capable of injecting into the RCS while in Mode 5. In this event, an SI pump was being used to fill and vent a Cold Leg Accumulator (CLA).

Shortly after starting the SI pump, an abnormal rise in RCS pressure occurred, prompting the operators to secure the SI pump. The abnormal RCS pressure rise occurred due to a crosstie valve being open. Prior to this event, a temporary clearance lift had been issued to open the subject crosstie valve for SI full flow testing, however, the crosstie valve was not closed after the testing, resulting in the abnormal RCS pressure rise.

On July 8, 2011, TVA submitted Revision 1 to LER 390/2011-001, "Safety Injection Pump " This LER described an incident Capable of Injecting into Reactor Coolant System in Mode 5.

The cause of WBN not meeting LCO 3.4.12 and the applicable Required Actions not being taken within their associated Completion Times in LER 390/2012-003 was that in impact to an Operations procedure was not identified as a result of a non-licensed individual performing the impact review. Therefore the event described in LER 390/2011-001 did not involve the same underlying cause or failure as the event being reported in this LER.

VII. ADDITIONAL INFORMATION (continued)

C. Additional Information

None D. Safety System Functional Failure This event did not result in a safety system functional failure in accordance with 10 CFR 50.72(a)(2)(v) and NEI 99-02.

E. Loss of Normal Heat Removal Consideration None

VIII. COMMITMENTS

None