05000387/LER-2017-009-01, Regarding Secondary Containment Declared Inoperable Due to Trip of Zone II Equipment Exhaust Fan
| ML18046A861 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 02/15/2018 |
| From: | Berryman B Susquehanna |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-7667 LER 2017-009-01 | |
| Download: ML18046A861 (5) | |
| 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) |
| 3872017009R01 - NRC Website | |
text
. FEB 1 *5 2018 Brad Berryman Site Vice President U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Susquehanna Nuclear, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.2904 Fax 570.542.1504 Brad.Berryman@TalenEnergy.com SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-388(387)/2017-009-01 UNIT 1 LICENSE NO. NPF-14 UNIT 2 LICENSE NO. NPF-22 PLA-7667 TALEN~
ENERGY 10 CFR 50.73 Docket No. 50-387 50-388 Attached is a supplement to Licensee Event Report (LER) 50-388(387)/2017-009-00.
The LER reported an event involving the loss of Secondary Contaimnent due to a trip of a Zone II Equipment Exhaust fan that was determined to be reportable in accordance with 10 CFR 50.73(a)(2)(v)(C) as a condition that could have prevented fulfillment of a safety function. This supplement includes additional information concerning the cause and
corrective actions
There were no actual consequences to the health and safety of the public as a result of this event.
This letter contains no new regulatory commitments.
Should you have any questions regarding this submittal, please contact Mr. Jason Jennings, Manager-Nuclear Regulatory Affairs at (570) 542-3155.
Attachment: LER 50-388(387)/2017-009-01 Copy:
NRC Region I Ms. T. E. Hood, NRC Project Manager Ms. L. H. Micewski, NRC Sr. Resident Inspector Mr. M. Shields, PA DEP/BRP
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150*0104 EXPIRES: 03/31/2020 (04-2017) httQ://W'W'N.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1 022/r3D the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 13. PAGE Susquehanna Steam Electric Station Unit 2 05000388 1 OF4
- 4. TITLE Secondary Containment Declared Inoperable Due to Trip of Zone II Equipment Exhaust Fan
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR REV MONTH DAY YEAR Susquehanna Steam Electric Station Unit 1 NUMBER NO.
05000387 09 16 2017 2017
- - 009
- - 01 6d I:; 2018 FACILITY NAME DOCKET NUMBER 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §:{Check all that apply) 1 0 20.2201(b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A) 0 20.2201(d)
D 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viii)(B) 0 20.2203(a)(1) 0 20.2203(a)(4) 0 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A) 0 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A) 0 50.73(a)(2)(iv)(A) 0 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) 0 73.71(a)(4) 0 20.2203(a)(2)(iii) 0 50.36(c)(2)
D 50.73(a)(2)(v)(B)
D 73.71(a)(5) 100 0 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
[8:1 50.73(a)(2)(v)(C) 0 73.77(a)(1) 0 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(D) 0 73.77(a)(2)(i)
D 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii) 0 73.77(a)(2)(ii) 0 50.73(a)(2)(i)(C) 0 OTHER Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT t rEPHONE NUMBER (lndude Area Code) l C. E. Manges, Jr., Senior Engineer-Nuclear Regulatory Affairs
](570) 542-3089
- 13. COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TOEPIX FACTURER TO EPIX X
VA CDMP T265 y
X VA FS U075 y
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR D YES (If yes, complete 15. EXPECTED SUBMISSION DATE) fZI NO SUBMISSION DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On September 16, 2017 at approximately 13:30, when performing a swap to place the Unit 2 "A" Reactor Building Equipment Compartment Exhaust fan (2V206A) in service, the fan tripped unexpectedly after being placed in service.
Reactor Building differential pressure lowered to < 0.25 inches water gauge (WG) due to the unexpected trip of 2V206A.
As a result, Technical Specification 3.6.4.1 Surveillance Requirement 3.6.4.1.1 was not met due to loss of Secondary Containment differential pressure. The 2V206B fan was placed back in service and Reactor Building differential pressure was restored to above 0.25 inches WG.
The condition is being reported in accordance with 10 CFR 50. 73(a)(2)(v)(C) as an event or condition that could have prevented fulfillment of a safety function.
The failure was not able to be replicated during investigation. The direct cause is inconclusive. A failure modes analysis was completed to identify the likely cause of the fan trip. Potential causes include one of the following: the flow control damper linkages binding, the low flow switch failing to reset, or the "A" and "B" fans running in parallel long enough to result in a low flow trip. A corrective action was identified to address each of these potential causes including greasing the linkages, testing the low flow switch reset and replacing the switch if necessary, and enhancing the affected procedures.
There were no actual consequences to the health and safety of the public as a result of this event.
NRC FORM 366 (04-2017)
)
CONDITIONS PRIOR TO EVENT
Unit 1 - Mode 1, approximately 100 percent Rated Thermal Power Unit 2 -Mode 1, approximately 100 percent Rated Thermal Power YEAR 2017
- 3. LER NUMBER SEQUENTIAL NUMBER
- - 009 There were no structures, systems, or components that were inoperable at the start of the event that contributed to the event.
EVENT DESCRIPTION
REV NO.
- - o1 I On September 16, 2017, a plant operator identified belts associated with the Unit 2 "B" Reactor Building Equipment Compartment Exhaust fan (2V206B) [EllS System/Component Identifier: VA/FAN] slipping and a hot burnt rubber smell in the area. The operator recommended swapping fans to place the "A" fan (2V206A) in service.
At approximately 13:30, when performing the swap to place the 2V206A fan in service, the 2V206A fan tripped unexpectedly after being placed in service. Reactor Building [EllS System Code: NG] differential pressure lowered to < 0.25 inches water gauge (WG). As a result, Technical Specification 3.6.4.1 Surveillance Requirement 3.6.4.1.1 was not met due to loss of Secondary Containment differential pressure. The 2V206B fan was placed back in service and Reactor Building differential pressure was restored to above 0.25 inches WG.
On September 16, 2017, at 15:53, this condition was reported (ENS#52973) in accordance with 10 CFR 50.72(b)(3)(v)(C) as an event or condition that, at the time of discovery, could have prevented the fulfillment of the safety function to mitigate the consequences of an accident by controlling the release of radioactive material. Susquehanna Steam Electric Station (SSES) has no redundant Secondary Containment System.
CAUSE OF EVENT
The failure was not able to be replicated during investigation. The direct cause is inconclusive.
A failure modes analysis was completed to identify the likely cause of the fan trip. Potential causes include the following:
- 1. Linkages on Flow Control Damper PDD27522A [EllS System/Component Identifier: VA/CDMP] could have been binding and prevented the damper from going open.
- 2. Low Flow Switch FSL27522A [EllS System/Component Identifier: VA/FS] could have failed to reset during the 2V206A start.
NRC FORM 3666 (04-2017)
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LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1 022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3[)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. LER NUMBER YEAR Susquehanna Steam Electric Station Unit 2 05000388 2017 SEQUENTIAL NUMBER
- - 009 REV NO.
- - 01
- 3. The procedure section for performing a fan swap includes the following caution statement: "Minimizing time between start of standby fan and subsequent shutdown of running fan will prevent low flow trip to occur. Low flow trip will occur if fans remain in parallel for approx. 30 seconds". Operator interviews indicated the discharge damper took longer than expected to open. The fans may have been running in parallel for longer than 30 seconds.
ANALYSIS/SAFETY SIGNIFICANCE
Based on engineering analysis of the event, secondary containment could have performed its safety function of isolating as assumed in the accident analysis and of re-establishing 0.25 inches of vacuum WG (drawdown) within the assumed accident analysis time (1 0 minutes).
This event will not be counted as a safety system functional failure (SSFF) for the NRC performance indicator based on the engineering analysis supporting the system's ability to fulfill the safety function.
CORRECTIVE ACTIONS
Due to the definitive cause being inconclusive, the remaining potential failure modes identified as unlikely are being addressed to minimize or eliminate an event similar to this. Corrective actions include the following:
- 1. Linkages on Flow Control Damper PDD27522A will be greased to reduce the probability of binding from occurring.
- 2. The reset for the Low Flow Switch FSL27522A will be tested to address the potential of an intermittent failure. If the reset test is unsatisfactory, the low flow switch will be replaced.
- 3. The caution statement in the applicable Unit 1 and 2 procedures will be revised to state "Leaving fans operating in parallel may cause a low flow trip. Securing a fan should be performed as soon as the discharge damper indicates dual position. Low flow trip will occur if flow remains below trip setpoint of 18,000 scfm for approximately 30 seconds."
COMPONENT FAILURE INFORMATION
Information for Flow Control Damper PDD27522A:
Manufacturer:
Trane Model:
CF40A3SW3CCUBSX Information for Low Flow Switch FSL27522A Manufacturer:
United Electric Controls Model:
J-6-142-9515 NRC FORM 3668 (04-2017)
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LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1 022, R.3 for instruction and guidance for completing this fonm http://www.nrc.gov/reading-nm/doc-collections/nuregs/staff/sr1 022/r30 Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMS control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
Susquehanna Steam Electric Station Unit 2 05000388
PREVIOUS SIMILAR EVENTS
The following are recent related LERs involving loss of secondary containment:
YEAR 2017
- 3. LER NUMBER SEQUENTIAL NUMBER
- - 009 LER 50-388(387)/2017-007-00, "Secondary Containment Declared Inoperable Due to Supply Air Flow," dated October 9, 2017.
LER 50-388(387)/2017-006-00, "Secondary Containment Declared Inoperable Due to Trip of Zone II Exhaust Fan," dated September 6, 2017.
REV NO.
- - o1 I LER 50-387(388)/2017-004-00, "Secondary Containment Declared Inoperable Due to Failure of an Exhaust Fan Breaker," dated August 4, 2017.
LER 50-388(387)/2017 -005-00, "Secondary Containment Declared Inoperable Due to Trip of Zone Ill Filtered Exhaust Fan," dated August 18, 2017.
LER 50-387(388)/2017-003-00, "Loss of Secondary Containment Zone 3 Due to Fan Trip," dated May 5, 2017.
LER 50-388(387)/2016-006-00, "Loss of Secondary Containment Due to Damper Controller Sticking," dated November 17, 2016.
LER 50-388(387)/2016-003-00, "Secondary Containment lnoperability Due to Failure to Meet Surveillance Requirement 3.6.4.1.1,"dated June 17, 2016.
LER 50-387(388)/2016-012-00, "Unit 2 HVAC Unable to Maintain Differential Pressure," dated May 26, 2016.
LER 50-387(388)/2016-003-00, "Unit 2 Zone 3 HVAC Unable to Maintain Differential Pressure," dated May 6, 2016.
LER 50-387(388)/2015-013-00, "Loss of Secondary Containment Due to Failure of Fans," dated February 2, 2016.
LER 50-387(388)/2015-012-00, "Loss of Secondary Containment Differential Pressure Due to Icing of the Intake Supply Plenum Screens," dated February 2, 2016.
LER 50-387(388)/2015-01 0-00, "Loss of Zone 2 During Unit 1 Reactor SCRAM," dated January 8, 2016.
LER 50-387(388)/2015-005-00, "Loss of Secondary Containment Due to Unit 2 Damper Alignment," dated June 25,2015.
LER 50-387(388)/2015-002-00, "Loss of Secondary Containment due to failure of running fans," dated June 10, 2015.
NRC FORM 3668 (04-2017)