05000259/LER-2013-007, Regarding High Pressure Coolant Injection System Declared Inoperable Due to an Inadvertent Actuation of the Primary Containment Isolation System

Regarding High Pressure Coolant Injection System Declared Inoperable Due to an Inadvertent Actuation of the Primary Containment Isolation System

ML13354B849
Person / Time
Site:	Browns Ferry
Issue date:	12/16/2013
From:	Polson K Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 13-007-00
Download: ML13354B849 (9)

LER-2013-007, Regarding High Pressure Coolant Injection System Declared Inoperable Due to an Inadvertent Actuation of the Primary Containment Isolation System

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2592013007R00 - NRC Website

text

Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabama 35609-2000 December 16, 2013 10 CFR 50.73 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Unit 1 Renewed Facility Operating License No. DPR-33 NRC Docket No. 50-259

Subject:

Licensee Event Report 50-25912013-007-00 The enclosed Licensee Event Report provides details of the High Pressure Coolant Injection System being declared inoperable due to an inadvertent actuation of the Primary Containment Isolation System. The Tennessee Valley Authority is submitting this report in accordance with Title 10 of the Code of Federal Regulations (10 CFR) 50.73(a)(2)(v)(B) and 10 CFR 50.73(a)(2)(v)(D).

There are no new regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact J. L. Paul, Nuclear Site Licensing Manager, at (256) 729-2636.

Respectfully, Vice President

Enclosure:

Licensee Event Report 50-259/2013-007 High Pressure Coolant Injection System Declared Inoperable Due to an Inadvertent Actuation of the Primary Containment Isolation System cc (w/ Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant

ENCLOSURE Browns Ferry Nuclear Plant Unit I Licensee Event Report 50-259/2013-007-00 High Pressure Coolant Injection System Declared Inoperable Due to an Inadvertent Actuation of the Primary Containment Isolation System See Enclosed

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 10/31/2013 (10-2010)

, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

3. PAGE Browns Ferry Nuclear Plant, Unit 1 05000259 1 of 7

4. TITLE: High Pressure Coolant Injection System Declared Inoperable Due to an Inadvertent Actuation of the Primar Containment Isolation System

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED I

IFACLITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR N/A 05000 NUMBER NO.

N 0

FACILITY NAME DOCKET NUMBER 10 16 2013 2013 -

007

" 00 12 16 2013 N/A 05000

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 0 20.2201(b)

[I 20.2203(a)(3)(i)

[l 50.73(a)(2)(i)(C)

[] 50.73(a)(2)(vii)

O 20.2201(d)

El 20.2203(a)(3)(ii)

[I 50.73(a)(2)(ii)(A) 0l 50.73(a)(2)(viii)(A) 10 20.2203(a)(1) 0l 20.2203(a)(4)

El 50.73(a)(2)(ii)(B)

El 50.73(a)(2)(viii)(B) 0_ 20.2203(a)(2)(i)

[I 50.36(c)(1)(i)(A)

El 50.73(a)(2)(iii)

[3 50.73(a)(2)(ix)(A) 10o. POWER LEVEL E 20.2203(a)(2)(ii) 0l 50.36(c)(1)(ii)(A)

[I 50.73(a)(2)(iv)(A)

[I 50.73(a)(2)(x) 0l 20.2203(a)(2)(iii)

[E 50.36(c)(2)

El 50.73(a)(2)(v)(A)

El 73.71 (a)(4)

El 20.2203(a)(2)(iv) 0l 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(B)

El 73.71(a)(5) 100 El 20.2203(a)(2)(v)

El 50.73(a)(2)(i)(A)

[I 50.73(a)(2)(v)(C)

[I OTHER 0l 20.2203(a)(2)(vi)

[E 50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D)

SpeciyinAbstractbeioworinNRC

12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)

Christopher Bennett, Licensing Engineer 256-729-2475MANU-REPORTABL MANU-REPORTABLE

CAUSE

SYSTEM COMPONENT MANU REPORTBLE

CAUSE

SYSTEM COMPONENT FACTU TO EPIX FACTURER TO EPIX FCUE OEI

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR SUBMISSION El YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 0 NO DATE N/A N/A N/A ABSTRACT (Limit to 1400 spaces, i e., approximately 15 single-spaced typewfitten lines)

On October 16, 2013, at 1032 hours0.0119 days <br />0.287 hours <br />0.00171 weeks <br />3.92676e-4 months <br /> Central Daylight Time, the Browns Ferry Nuclear Plant, Unit 1, High Pressure Coolant Injection (HPCI) System unexpectedly received a Group 4, Primary Containment Isolation System (PCIS) signal during the performance of surveillance procedure 1-SR-3.3.5.1.2(ATU D), Core and Containment Cooling Systems Analog Trip Unit Functional Test. Operations personnel declared the HPCI System inoperable and entered Technical Specification 3.5.1, Emergency Core Cooling System-Operating, Condition C.

The Group 4, PCIS signal isolated the steam flow path to the HPCI turbine, resulting in the HPCI System being unavailable for approximately 14 minutes. The HPCI System isolation and unavailability is considered a safety system functional failure of a single-train system preventing accident mitigation and residual heat removal.

The root cause of this event was determined to be the workers not applying human error reduction tools appropriately, resulting in a procedure step not being completed as written.

The corrective action to prevent recurrence was to perform appropriate disciplinary action with the workers involved in the HPCI isolation in accordance with Human Resource process and procedures.

NRC FORM 366 (10-2010)

1.

Plant Operating Conditions Before the Event

At the time of the event, Browns Ferry Nuclear Plant (BFN), Unit 1, was in Mode 1 at approximately 100 percent rated thermal power.

111. Description of Events A. Event:

On October 16, 2013, at 1032 hours0.0119 days <br />0.287 hours <br />0.00171 weeks <br />3.92676e-4 months <br /> Central Daylight Time (CDT), BFN, Unit 1, High Pressure Coolant Injection (HPCI) [BJ] System unexpectedly received a Group 4, Primary Containment Isolation System (PCIS)[BD] signal during the performance of surveillance procedure 1-SR-3.3.5.1.2(ATU D), Core and Containment Cooling Systems Analog Trip Unit Functional Test. Due to the Group 4 isolation, which provides isolation of the HPCI System, operations personnel declared the HPCI System inoperable and entered Technical Specification (TS) 3.5.1, Emergency Core Cooling System (ECCS)-Operating, Condition C and Abnormal Operating Instruction 1-AOI-64-2B, Group 4 High Pressure Coolant Injection Isolation.

Upon investigation of the isolation, it was discovered that the current input to the Analog Trip Unit (ATU) was incorrect. The step in the procedure that required the stable current amplitude on the calibration unit to be set to between 3.9 mADC and 4.1 mADC had not been completed as required. When the HPCI Steam Line Flow -

HPCI Isolation Instrument Loop was removed from service for test, the input current for the ATU was still set at approximately 20 mADC. As a result of the incorrect current input, Unit 1 HPCI steam flow isolated; thereby rendering it unavailable for approximately 14 minutes. On October 16, 2013, at approximately 1046 hours0.0121 days <br />0.291 hours <br />0.00173 weeks <br />3.98003e-4 months <br /> CDT, the HPCI System was made available for service, but Operations personnel decided that the HPCI System would remain inoperable until satisfactory completion of the surveillance procedure.

LCO 3.5.1 requires each Emergency Core Cooling System (ECCS) [BJ] [BM] [BO]

injection/spray subsystem and the Automatic Depressurization System (ADS) [SB]

function of six safety/relief valves [V] to be Operable in Mode 1 and Modes 2 and 3, except HPCI and ADS valves are not required to be Operable with reactor steam dome pressure less than or equal to 150 psig. Condition C of TS 3.5.1 was entered due to the Group 4, PCIS isolation. Required Action C.1 of TS 3.5.1 requires that the Reactor Core Isolation Cooling (RCIC) System [BN] be verified Operable immediately and Required Action C.2 of TS 3.5.1 requires that the HPCI System be restored to Operable status within 14 days.

On October 16, 2013, at 1032 hours0.0119 days <br />0.287 hours <br />0.00171 weeks <br />3.92676e-4 months <br /> CDT, operations personnel verified the RCIC System to be Operable. On October 16, 2013, at 1503 hours0.0174 days <br />0.418 hours <br />0.00249 weeks <br />5.718915e-4 months <br /> CDT, following successful completion of surveillance procedure 1-SR-3.3.5.1.2(ATU D), operations personnel declared the HPCI System Operable and exited TS 3.5.1, Condition C.

B. Status of structures, components, or systems that were inoperable at the start of the event and that contributed to the event

There were no structures, components, or systems that were inoperable at the start of the event that contributed to the event.

C. Dates and approximate times of occurrences

October 16, 2013, at 0835 hours0.00966 days <br />0.232 hours <br />0.00138 weeks <br />3.177175e-4 months <br /> CDT October 16, 2013, at 1032 hours0.0119 days <br />0.287 hours <br />0.00171 weeks <br />3.92676e-4 months <br /> CDT October 16, 2013, at 1036 hours0.012 days <br />0.288 hours <br />0.00171 weeks <br />3.94198e-4 months <br /> CDT October 16, 2013, at 1046 hours0.0121 days <br />0.291 hours <br />0.00173 weeks <br />3.98003e-4 months <br /> CDT October 16, 2013, at 1503 hours0.0174 days <br />0.418 hours <br />0.00249 weeks <br />5.718915e-4 months <br /> CDT October 16, 2013, at 1608 hours0.0186 days <br />0.447 hours <br />0.00266 weeks <br />6.11844e-4 months <br /> CDT Maintenance personnel began work on surveillance procedure 1-SR-3.3.5.1.2(ATU D).

BFN, Unit 1, HPCI System unexpectedly received a Group 4, PCIS signal.

Operation personnel declared the HPCI System inoperable in accordance with TS 3.5.1, Condition C.

The Group 4 isolation was reset.

The HPCI System was made available, but remained inoperable until satisfactory completion of the surveillance procedure.

Surveillance procedure 1-SR-3.3.5.1.2(ATU D) was successfully completed, and operations personnel declared the HPCI System Operable and exited TS 3.5.1, Condition C.

BFN reported the event to the NRC in accordance with 50.72(b)(3)(v)(D).

D. Manufacturer and model number (or other identification) of each component that failed during the event:

There was no failure of a component for this event.

E. Other systems or secondary functions affected

There were no other systems or secondary functions affected.

F. Method of discovery of each component or system failure or procedural error

This event was self revealing during the performance of surveillance procedure 1-SR-3.3.5.1.2(ATU D) when an inadvertent Group 4, PCIS signal was received.

G. The failure mode, mechanism, and effect of each failed component, if known:

There was no failure of a component. The problem was the failure to complete a surveillance procedure step to adjust the current input to the ATU which resulted in the Group 4 isolation, entry into TS 3.5.1, Condition C, and the unplanned HPCI System inoperability.

H. Operator actions

Operations personnel entered 1-AOI-64-2B, declared the HPCI System inoperable, entered TS 3.5.1, Condition C, and verified that the RCIC System was Operable by administrative means.

I. Automatically and manually initiated safety system responses

There were no automatically or manually initiated safety system responses.

Ill.

Cause of the event

A. The cause of each component or system failure or personnel error, if known:

Immediate Cause The immediate cause of this event was failure to adjust the stable current amplitude on the calibration unit to the ATU.

Root Cause The root cause of this event was determined to be failure to complete a step in surveillance procedure 1-SR-3.3.5.1.2(ATU D).

B. The cause(s) and circumstances for each human performance related root

cause

During the performance of the surveillance procedure on October 16, 2013, the instrument mechanics failed to use three way communication and placekeeping adequately. By not applying human error reduction tools appropriately, the workers allowed themselves to become complacent, resulting in a procedure step not being completed as written.

IV. Analysis of the event

The Tennessee Valley Authority (TVA) is submitting this report in accordance with 10 CFR 50.73(a)(2)(v)(B) and 10 CFR 50.73(a)(2)(v)(D), as any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to remove residual heat and mitigate the consequences of an accident.

This event was the result of a failure to complete a surveillance procedure step to adjust the current input to the ATU which resulted in the HPCI System isolation and inoperability. When the ATU channel was removed from service, the logic actuated as designed, resulting in a HPCI System isolation on high amplitude. All systems and components functioned as designed.

The pre-job briefing for the surveillance identified that use of the 2-minute rule and procedure compliance would mitigate risk and prevent adverse consequences. Workers indicated that they were aware of the risk to the system, but no special precautions were taken to mitigate the risk. The workers utilized the reader/performer methodology during the performance of the surveillance. Workers stated that at the start of the surveillance, they were utilizing human error reduction tools effectively, but as they became more comfortable in the performance of the surveillance, standards relaxed and the workers became complacent. Prior to the missed surveillance step, associated tasks required the reader to divert his attention from the task allowing focus to be lost on the actual surveillance performance. The reader stated that he never heard the performer repeat the surveillance step to set the stable current amplitude of the calibration unit to between 3.9 mADC and 4.1 mADC, but initialed the step as complete anyway. The performer stated that he never heard the surveillance step read and took no action as a result.

Analysis of the event concluded that the HPCI System isolation was the result of an isolated human error in which workers did not complete a surveillance procedure step as written. The identified weakness was worker practices, in that the human error reduction tools; three-way communication, procedure use and adherence, and place keeping were not applied adequately.

V.

Assessment of Safety Consequences

The HPCI System consists of a steam turbine-driven system driving a constant-flow pump assembly to inject either Condensate Storage Tank [KA] water or Suppression Pool [BT] water into the reactor under emergency conditions. The HPCI System provides adequate core cooling for all break sizes which do not result in rapid depressurization of the reactor vessel and functions independent of off-site power sources and Emergency Diesel Generators [EK].

The Safety Consequences Evaluation concluded that there was a minimal reduction in the defense in depth to Nuclear Safety and no reduction in the defense in depth to Industrial Safety, Radiological Safety, or Environmental Safety.

A. Availability of systems or components that could have performed the same function as the components and systems that failed during the event:

This event resulted in the HPCI System being inoperable. The RCIC System and all other ECCS Systems remained Operable to maintain adequate core cooling during the period of HPCI System inoperability.

B. For events that occurred when the reactor was shut down, availability of systems or components needed to shutdown the reactor and maintain safe shutdown conditions, remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident:

The BFN, Unit 1, was not shut down during this event.

C. For failure that rendered a train of a safety system inoperable, an estimate of the elapsed time from discovery of the failure until the train was returned to service:

The HPCI System was declared inoperable on October 16, 2013, at 1032 hours0.0119 days <br />0.287 hours <br />0.00171 weeks <br />3.92676e-4 months <br /> CDT, and made available for service 14 minutes later on October 16, 2013, at 1046 hours0.0121 days <br />0.291 hours <br />0.00173 weeks <br />3.98003e-4 months <br /> CDT. However, the HPCI System remained inoperable until successful completion of the surveillance on October 16, 2013, at 1503 hours0.0174 days <br />0.418 hours <br />0.00249 weeks <br />5.718915e-4 months <br /> CDT.

VI.

Corrective Actions

Corrective Actions are being managed by TVA's corrective action program under Problem Evaluation Report (PER) 794807.

Immediate Corrective Actions

Removed the task qualifications for the workers involved in the performance of surveillance procedure 1-SR-3.3.5.1.2(ATU D) and conducted a briefing to the Instrument Maintenance shop to communicate the lessons learned from the HPCI System isolation event.

Corrective Actions to Prevent Recurrence or to Reduce Probability of Similar Events Occurring in the Future Perform appropriate disciplinary action, in accordance with Human Resource process and procedures, with the workers involved in the HPCI System isolation.

VII.

Additional Information

A. Previous similar events at the same plant:

A search of BFN Licensee Event Reports (LERs) for Units 1, 2, and 3 for the last five years identified the following similar LERs:

LER 50-260/2009-009-00, Inadvertent Isolation of the High Pressure Coolant Injection System During Testing Activities. This LER identified a similar condition concerning a HPCI System isolation during testing; however, the isolation was due to a faulty test connector.

LER 50-260/2010-004-00, Inadvertent Isolation of the High Pressure Coolant Injection System During Testing Activities. This LER identified a similar condition concerning a HPCI System isolation during testing; however, the isolation was due to failure of relay contact protective boots.

LER 50-260/2010-005-00, High Pressure Coolant Injection System Isolation Experienced During Performance of HPCI Steam Supply Low Pressure Functional Test. This LER identified a similar condition concerning a HPCI System isolation during testing; however, the isolation was due to lack of clear procedure guidance with regards to usage of multiple volt ohm meters.

LER 50-260/2012-004-00, High Pressure Coolant Injection System Rendered Inoperable Due to an Inadvertent Actuation of Primary Containment Isolation. This

LER identified a similar condition concerning a HPCI System isolation during testing; however, the isolation was due to incorrect wire bending practices to assemble steam line space high temperature switches.

The reasons for these HPCI System isolations and the corrective actions reported in these LERs do not directly relate to this event and would not have prevented this event from occurring.

A search was performed on the BFN corrective action program. The previous problem evaluation reports (PERs) associated with the above similar LERs are PERs 208627, 235338, 239313, and 596706.

Additional similar PERs related to the condition reported in this LER are PERs 368764, 660862, and 695846. These PERs involve conditions related to inadvertent system actuations.

A review of the corrective actions for these PERs concluded that the corrective actions associated with these PERs would not have prevented this event from occurring.

B. Additional Information

There is no additional information.

C. Safety System Functional Failure Consideration:

In accordance with Nuclear Energy Institute 99-02, this event is considered a safety system functional failure.

D. Scram with Complications Consideration:

This event did not result in an unplanned scram with complications.

VIII. COMMITMENTS

There are no commitments.