05000259/LER-2019-001-01, High Pressure Coolant Injection System Declared Inoperable Due to Steam Supply Isolation
| ML19311C475 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 11/07/2019 |
| From: | Bono S Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 2019-001-01 | |
| Download: ML19311C475 (8) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 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)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 2592019001R01 - NRC Website | |
text
Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabama 35609-2000 November 7, 2019 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 50-259/2019-001-01 10 CFR 50.73
Reference:
Letter from TV A to NRC, "Licensee Event Report 50-259/2019-001-00," dated September 6, 2019 (ML19249C129)
On September 6, 2019, the Tennessee Valley Authority (TVA) submitted Revision Oto Licensee Event Report (LER) 50-259/2019-001-00 (Reference) which provided details of the High Pressure Coolant Injection system which was declared inoperable due to steam supply isolation. The enclosed LER has been revised to update the cause of the event and the
corrective actions
TV A is submitting this report in accordance with Title 10 of the Code of Federal Regulations 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 mitigate the consequences of an accident.
There are no new regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact J. L. Paul, Site Licensing Manager, at (256) 729-7874.
U.S. Nuclear Regulatory Commission Page 2 November 7, 2019 Enclosure: Licensee Event Report 50-259/2019-001 High Pressure Coolant Injection System Declared Inoperable due to Steam Supply Isolation cc (w/ Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant NRC Project Manager - Browns Ferry Nuclear Plant
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)
, the NRC may net conduct or sponsor, and a person is net required to respond lo, the information collecoon.
- 13. Page Browns Ferrv Nuclear Plant Unit 1 05000259 1 OF 6
- 4. Title High Pressure Coolant Injection System Declared Inoperable due to Steam Supply Isolation
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved I
Sequential I Rev Facility Name Docket Number Month Day Year Year Month Day Year NIA NIA Number No.
07 12 2019 2019 001 01 11 07 2019 Facility Name Docket Number NIA NIA
- 9. Operating Mode
- 11. This Report is Submitted Pursuant to the Requirements of 10 CFR §: (Check all that apply) 0 20.2201 (b)
D 20.2203(a)(3)(i) 0 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A) 1 0 20.2201 (d)
D 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B)
D 20.2203(a)(1)
D 20.2203(a)(4)
D 50.73(a)(2)(iii)
D 50.73(a)(2)(ix)(A)
D 20.2203(a)(2)(i) 0 50.36(c)(1 )(i)(A)
D 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
- 10. Power Level D 20.2203(a)(2)(ii) 0 50.36(c)(1 )(ii)(A)
D 50.73(a)(2)(v)(A)
D 73.71(a)(4)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(B)
D 73.71(a)(5)
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(C)
D 73.77(a)(1) 100 D 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 1:8] 50.73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 73.77(a)(2)(ii) 0 50.73(a)(2)(i)(C) 0 OTHER Specify in Abstract below or in
C. Dates and approximate times of occurrences
Dates and Approximate Times Occurrence YEAR 2019 -
- 3. LER NUMBER SEQUENTIAL NUMBER 001 July 12, 2019, 1640 CDT July 12, 2019, 2110 CDT HPCI isolation occurs. HPCI declared inoperable.
HPCI returned to operational status. Total time HPCI was inoperable was 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 30 minutes.
D. Manufacturer and model number 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
No other systems or secondary functions were affected by this event.
F. Method of discovery of each component or system failure or procedural error
The event was self revealing when a Group 4 PCIS signal was received.
G. The failure mode, mechanism, and effect of each failed component
There was no failure of a component for this event.
H. Operator actions
REV NO.
01 Operations personnel declared the HPCI system inoperable, entered 1-AOl-64-2b, entered TS 3.5.1, Condition C, and verified that the RCIC system was operable.
I.
Automatically and manually initiated safety system responses
During this event, an inadvertent Group 4 PCIS isolation of the HPCI system occurred. A Group 4 PCIS isolation closes the steam supply valves to HPCI in the event of high steamline space temperature, high steam flow, low steamline pressure, or high pressure between diaphragm rupture discs on the HPCI turbine exhaust. These signals are indicative of a line break in the HPCI system steamline to the turbine or high pressure in the turbine steam supply line. At the time of the event, these conditions did not exist.
Ill.
Cause of the event
A. Cause of each component or system failure or personnel error The direct cause of this event was that Electrical Maintenance personnel tested incorrect electrical termination points during the performance of EPl-0-075-RL Y001 which resulted in an unexpected Group 4 PCIS actuation.
The workers failed to follow EPl-0-075-RL Y001 as written by not verifying panel number or wire number, and by failing to use a peer check as required. Additionally, the workers failed to apply maintenance fundamentals and technical skills with appropriate rigor when using test equipment.
IV.
Analysis of the event
Workers were performing a functional test of the Pressure Suppression Chamber Head Tank pump suction valve interlock relays [EIIS:RL Y] per EPl-0-075-RL Y001. Workers failed to recognize that the terminal connections for the tested relays were in two different panels (Panel 1-9-32 and Panel 1-9-33). Both panels have the same terminal nomenclature, so the terminal points in Panel 1-9-32 were incorrectly tested instead of the terminal points in Panel 1-9-33.
Additionally, maintenance fundamentals regarding test equipment use were not applied to ensure that the continuity checks were adequate.
The HPCI system is provided to assure that the reactor is adequately cooled to limit fuel cladding temperature in the event of a small break in the nuclear system and loss of coolant which does not result in rapid depressurization of the reactor vessel. The HPCI system permits the nuclear plant to be shut down, while maintaining sufficient reactor vessel water inventory until the reactor vessel is depressurized. The HPCI system continues to operate until the reactor vessel pressure is below the pressure at which Low Pressure Coolant Injection [EIIS:BO] operation or Core Spray system [EIIS:BM] operation maintains core cooling. In this event, HPCI would have been unable to perform its safety function while the steam supply isolation valves were closed due to the Group 4 PCIS isolation.
V.
Assessment of Safety Consequences
This event resulted in inoperability of the single train of the HPCI system resulting in the inability of the HPCI system to fulfill its safety functions to remove residual heat and mitigate the consequences of an accident. During this event, the RCIC system remained operable and the ADS system was operable to facilitate core cooling by low pressure ECCS systems if needed.
The cause of the Group 4 PCIS isolation was determined and HPCI was returned to service in a short time (4.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) and within the allowed outage time of TS 3.5.1. During the time period that 01 the HPCI system was inoperable, sufficient systems were available to provide the required safety functions to protect the health and safety of the public. Based on the above, the TVA has concluded that sufficient systems were available to provide the required safety functions needed to protect the health and safety of the public.
A. Availability of systems or components that could have performed the same function as the components and systems that failed during the event During this event, RCIC was verified as operable by Operations personnel and all other ECCS and ADS systems remained operable.
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 This event did not occur when the reactor was shutdown.
C. For failure that rendered a train of a safety system inoperable, estimate of the elapsed time from discovery of the failure until the train was returned to service HPCI was inoperable from the time of the Group 4 PCIS actuation on July 12, 2019 at 1640 CDT until it was returned to service on July 12, 2019 at 2110 CDT. The lapsed time for inoperability of the HPCI system was 4.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.
VI.
Corrective Actions
Corrective Actions are being managed by the TVA's corrective action program under Condition Report (CR) 1532170.
A. Immediate Corrective Actions
- 1. The involved workers were immediately removed from the field with the workers disqualified and remediated prior to being returned to work.
- 2. All work performed from the time of the event was risk reviewed by shop superintendents and approved by maintenance director until the issue could be defined and communicated.
- 3. The Maintenance department implemented a "Stop Work" on Monday July 15, 2019 to inform workers of this event.
01 B. Corrective Actions to Prevent Recurrence or to reduce the probability of similar events occurring in the future
- 1. Accountability for individuals involved in the event was implemented in accordance with TVA's processes.
- 2. The electrical maintenance shop was briefed on the causes and lessons learned from the event.
- 3. A dynamic learning activity with electricians involved has been performed to cover volt-ohm meter usage. Completion of the action includes worker demonstration of volt-ohm meter usage.
VII. Previous Similar Events at the Same Site
A search of BFN Licensee Event Reports (LERs) for Units 1, 2, and 3 within the last three years identified one previous event involving a HPCI isolation that caused HPCI to be inoperable.
LER 259/2018-004-01 reported a HPCI isolation that occurred on July 9, 2018. During performance of surveillance procedure 1-SR-3.3.6.1.2(38), High Pressure Coolant Injection System Steam Supply Low Pressure Functional Test, an unexpected HPCI isolation occurred.
The most likely cause of the unexpected Unit 1 HPCI isolation was operation of a pressure switch near the manufacturer's electrical contact current ratings. No personnel error was involved in this event.
VIII. Additional Information
There is no additional information.
IX.
Commitments
There are no new commitments.
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