05000281/LER-2020-001, Loss of Containment Cooling Affecting Partial Pressure Indication
| ML21027A120 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 10/01/2020 |
| From: | Lawrence D Virginia Electric & Power Co (VEPCO) |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML21027A122 | List: |
| References | |
| 20-352 LER 2020-001-00 | |
| Download: ML21027A120 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability |
| 2812020001R00 - NRC Website | |
text
October 1, 2020 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555-0001
Dear Sir or Madam_:
10CFR50.73 Virginia Electric and Power Company Surry Power Station 5570 Hog Island Road Surry, Virginia 23883 Serial No.:
20-352 SPS:
MMT Docket No.: 50-281 License No.: DPR-37 Pursuant to 10CFR50.73, Virginia Electric and Power Company hereby submits the following Licensee Event Report applicable to Surry Power Station,Unit 2.
Report No. 50-281 / 2020-001-00 This report has been reviewed by the Station Facility Safety Review Committee and will be forwarded to the Management Safety Review Committee.
ence S
dent Enclosure Commitment contain~ In this letter: None cc:
U.S. Nuclear Regulatory Commission, Region II Marquis One Tower, Suite 1200 245 Peachtree Center Ave:, NE Atlanta, GA 30303-1257 NRC Senior Resident Inspector Surry Power Station er Station
be:
Mr. Dan G. Stoddard Mr. Mark D. Sartain Mr. Gregg Crenshaw Ms. Kathryn Barret Mr. Douglas C. Lawrence Mr. Fred Mladen Mr. John R. Daugherty Mr. Jerry Bischof Mr. Johnny W. Henderson Mr. James Jenkins Ms. Lori J. Armstrong Mr. David H. Wilson Mr. James Holloway Mr. Geoffrey HIii Mr. Jeffrey Helbing Mr. Russell A Hamilton Ms. William Summers Mr. ADen Harrow Mr. Rich Phllpot Mr. Bill Standley Mr. Matt Adams Mr. Ted Shashaty Mr. James E. ColMns Mr. Mark S. Boone Mr. Craig Sly Mr. Nell Turner Mr. Jeffrey A Langan Mr. James R. Schleser Ms. Natalie A Yonker Mr. Tom A. Brookmire Ms. Lauren Lopez Mr. Michael N. LaPrade Mr. Percy Davis Mr. Gary D. Miner Mr. Jim R. Roth Ms. Jennifer C. Pollard Mr. Keith Dowdy Mr. Andrew Volkovltskly Mr. Kurt Rowland Licensing File Serial No. 2~352 LER 281-202~001-00 Loss of Containment Cooling Affecting Containment Partial Pressure Indication be page 1 of 2 SVP & CNO Dominion Nuclear Vice President, Nuclear Engineering & Fleet Support Director Corporate Risk Management Corp. Licensing GOV 02-548)/Corporate Records SPS, Site Vice President NAPS, Site Vice President MPS, Site Vlce President SVP Nuclear Ops & Fleet Performance SPS, Director Station Safety and Licensing NAPS, Director Station Safety and Licensing MPS, Director Station Safety and Licensing SPS, Plant Manager SPS, Director Nuclear Site Engineering SPS, Manager Nuclear Training SPS, Manager Maintenance SPS, Manager Nuclear Operations SPS, Manager Nuclear Organization Effectlveness SPS, Manager Engineering Systems Programs SPS, Manager Licenslng/EP Director Nuclear Regulatory Affairs Director Nuclear Engineering & Fuels Manager Nuclear Quality Manager Nuclear Emergency Preparedness Manager Corporate Risk Engineering Manager Corporate Licensing NAPS, Manager Ucensing/EP MPS, Manager Licensing NAPS, Manager Nuclear Organiz~tion Effectiveness MPS, Manager Nuclear Organization Effectiveness Manager Nuclear Fuel Procurement Supervisor Nuclear Safety Analysis Supervisor Fuel Performance Analysis Nuclear Perfo'rmance Assessment IN/2SE, Licensing IN/2SE, Nuclear Regulatory Affairs SPS, OR/OE SPS, CAP-OR/OE SPS, Equipment Reliability and Pred. Analysis SPS, Maintenance Rule Coordinator SPS, Licensing
Serial No.20-352 LER 281-2020-001-00 Loss of Containment Cooling Affecting Containment Partial Pressure Indication be page 2 of 2 Concurrence - See Correspondence Routing and Approval Sheet Verification of Accuracy
- 1. CR 1152857, "2-CD-P-48-MOTOR Breaker TrippedD
- 2. CR 1154065, "Containment Air Partial Pressure Calculation*
- 3. SPS Unit 2 Control Roor:n Log - Event Timeline [08/04/2020 1840 - 2056]
- 4. SPS Engineering Department Log - Unit 2 Containment Partial Pressure [09/24/2010 1733]
Action Plan Issue ETE to clarify when an ARP manual calculation of containment air Is required and document the technical basis behind the review.
Changes to the UFSAR or QA Topical Report None I
I
- I t
Abstract
At 1840 [EST] on August 4, 2020, with Unit 2 at 100% power. the Unit 2 Containment Chiller (2-CD-REF-1) tripped due to the Unit 2 B Chilled Water Pump (2-CD-P-4B) for 2-CD-REF-1 tripping. Both channels of containment partial pressure alarmed shortly thereafter. After initiating applicable Annunciator Response Procedures (ARPs), both channels of containment partial pressure were declared inoperable per ARP guidance. In accordance with the ARP's a surveillance clock was initiated to manually calculate partial pressure within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Partial pressure readings returned to pre-event values following restoration of cooling provided from chilled Component Cooling (CC) to Unit 2 containment. As a result, the applicable Unit 2 ARP's were exited at 2056 [EST].
This report is submitted pursuant to 10 CFR 50.73(a)(2)(vii) due to an event where a single cause or condition caused at least one independent train or channel to become inoperable in multiple systems or two independent trains or channels to become inoperable in a single system designed to: (D) mitigate the consequences of an accident, and 10 CFR 50. 73{a)(2)(v) due to an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to: (D) mitigate the consequences of an accident.
The safety consequences associated with this event were determined to be of very low significance. Unit 1 was not impacted by this event.
NRC FORM 368A (08-2020)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OIIIB: NO. 3150-0104 EXPIRES! 08#31/2023 LICENSEE EVENT REPORT (LER)
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SEQUl!HTIAL REV 120201-1 N~ 1-1 : I
NARRATIVE
A Plant Operation Conditions Before the Event Event Date: 08/04f2020 Unit 1: 100 Percent Power Unit 2: 100 Percent Power
Background:
The Chlled WaJ.er (CO) system Is provided for each reactor unit and Is designed to be capable of providing cooling to the chilled Component Cooling (CC) heat exchangers. 'Mlen the unit Is online the CO system Is used to supplement containment cooling.
Containment partial pressure Is the pressure of the air within the containment building (partial pl'888llra = total pressure -
water vapor pressure). The containment Is essentially leak tight as verified by Type A testlng, therefore mass In contalnmeot and the volume of contaiMlent does not change unless operational manipulations occur (containment vacuum pump operation or containment Instrument air compressor). Following a containment chiller trip, containment temperature will Increase, and based on the Ideal Gas Law, as temperature Increases so w1n air partial pressure.
B. Description of Event
On 8/412020 at 18:35, 2-C~-1 (Unit 2 Containment Chiller) hipped due to 2-CD-P-4B (Chilled water Pump for 2-CD-REF-0 tripping. At 18:40, both channels of partial pressure alarmed for being -0.1 psi from setpoinl Ari nunciator Response Procedures (ARP) 2B-A6 and 28-86 were performed declaring both channels of Unit 2 Containment Partial Pf888ure Inoperable resulting in no direct indicatlon of containment partial pl'888ure, At 19:32, U2 Containment cooling was swapped from chilled CC and placed on normal CC. At 20:56, folowfng restoration of chllled CC, contai'lment partial pressure Indication waa considered operable and ARP's 2B-A6 and 2B-B6 were exited.
ARP 28-86, CTMT PART PRESS -0.1 PSI CH 2, gufdance Included the following CAUTION statement:
- - rrtp of the operating ~Iller Unit causes enough change In the air temperature being sensed by the RTDs that Indicated partial pressure may decrease to less than the minimum pre88ure allowed by Technical Specification Figure 3.8-1. CTMT partial pressure Indication less than the minimum pressure allowed by Technical Speclflcetlon Flgure 3.8-1 due to chiller trip or known chUler or Chilled Water evolution does NOT constitute violation of Tech Spec 3.8."
Addltlonally, Attachment 2, Calculation of CTMT Partial Pressure has a NOTE with the first bullet that provides the following guidance:
"This calculation Is required at a minimum of awry 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to satisfy Tech Spec 3.8. However, If CTMT cooling conditions change adversely, this calculation should be performed more frequently, at the discretion of Shift Supervision."
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YEAR 8EQU1!NTIAL RSV 12020 1-1 ~
1-1 ~: I NARRATIVE The guklance provided In the annunciator response procedure Is based on fleet operating experience and similar to wording oontafned In a plant procedure at a comparable reactor design. A site specific analysis did not exist at the time the ARP was revised fo conflnn the accuracy of the caution In transient containment temperature conditions. In the absence of the caution, a contailment chmer trip would result In entering a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> Technical Specification (TS) action statement to restore containment conditions to within the prescribed TS 3.8 operating envelope. Based on the caution the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> action statement was not entered. Since a site specific analysis did not exist for the caution, it may have been more appropriate to enter the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> TS action atatement until a site specific calculation which Included relative humidity or dew point could have been performed to confirm that containment conditions remained within TS required operating envelope llmlt8.
This condition is being reported since, In the moment, a site specific analysis did not exist to verify accuracy of the caution for transient conditions, which was used to not enter a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> Techn1cal Specification action statement It Is Important to note that subsequent engineering analysis confirmed the accuracy of the caution. The calcuJatlon will be captured In an Engineering Technical Evaluation (ETE) to clarify when an ARP manual calculation of containment air Is required and document the technical basis behind this review. This ETE is already prepared and In final review. The annunciator response procedures 28-AS, CTMT PART PRESS -0.1 PSI CH 1 and 28-86, CTMT PART PRESS -0.1 PSI CH 2 have been revised to Improve accuracy and to clarify when a sample of the containment atmosphere Is required.
C. Cause of Event
The direct cause of the event was due to 2-CD-P-48 tripping. The loss of 2-CD-P-4B resultad In 2-CD-REF-1 tripping leading to a loss of cooling to Unit 2 containment thereby Increasing the containment temperature, causing the containment partial pressure alarms ultimately rendering the containment partial pressure channels Inoperable and no vaUd lndlcatlon of contaim1ent partial pressure.
D. Safety Consequence
The safety consequences associated with this event were determined to be of very low significance. Engineering analysis detennined that contalrunent partial pressure remained within the allowable envelope required by Technical Specification 3.8 during the entire time period.
Risk Significance:
The risk associated with the Inoperable channels of Unit 2 Containment Partial Pressure la very low. Following a chDler trip, containment temperature wiD Increase. Following the Ideal Gas Law, as temperature Increases so w1a air partial pressure. Based on a review of data trends for contalnment weighted average temperature, the maximum containment weighted average temperature change was 5.4 deg F. Engineering analysis conflnned that with a SefVlce Water (SW) temperature ot 89 deg F and a containment weighted average temperature rise of 5.4 deg F, containment partial prassure remained within the allowable envelope required by Tech Spec 3.8.
NRC FORM 36&\\ (03-3l2ll)
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- 1. FACILITY NAME
!Surry Power Shlllon, Unit 2 NARRATIVE
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~ER 1-1 ~: I
- 1. ARP's 1 / 28-A6 and 1 / 28--86 have been revised to improve accuracy and to clarify when a sample of the containment atmosphere Is required.
Corrective Actions (Planned)
- 1. An Engineering Technical Evaluation (ETE} will be Issued to clarify when an ARP manual calculation of containment air is required and document the technical bas!~ behind this review. Th Is ETE Is already prepared and In final review.
F. Previous Occurrences
No previous Licensee Event Reports which could be comparable to this event were found.
G. Component FaDure Yes. 2..CD-P-4B motor field cable to motor lead connection was completely separated due to extreme overheating. The motor was manufactured by Emerson Electrlcal Company.
NACFORM3W.~
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