NL-18-1028, Manual Reactor Trip Due to High Steam Generator Water Level

Manual Reactor Trip Due to High Steam Generator Water Level

ML18242A369
Person / Time
Site:	Vogtle
Issue date:	08/30/2018
From:	Gayheart C Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-18-1028
Download: ML18242A369 (4)

Text

~ Southern Nuclear AUG 3 0 2018 Docket No:

50-424 U.S. Nuclear Regulatory Commission A TIN: Document Control Desk Washington, D.C. 20555-0001 Regulatory Affairs Vogtle Electric Generating Plant-Unit 1 Licensee Event Report 2018-001-00 Manual Reactor trip due to High Steam Generator Water Level Ladies and Gentlemen:

3535 Colonnade Parkway Post Office Box 1295 Birmingham, AL 35243 205 992 5000 tel NL-18-1028 In accordance with the requirements of 10 CFR 50.73(a)(2)(iv)(A), Southern Nuclear Operating Company is submitting the enclosed Licensee Event Report, 2018-001-00 for Vogtle Electric Generating Plant Unit 1. This letter contains no NRC commitments. If you have any questions, please contact Matt Horn (706) 848-1544.

Respectfully submitted, Cheryl Jli heart Regulatory Affairs Director CAG/KCW

Enclosure:

Unit 1 Licensee Event Report 2018-001-00 Cc: Regional Administrator NRR Project Manager-Vogtle 1 & 2 Senior Resident Inspector-Vogtle 1 & 2 RType: CVC7000

Vogtle Electric Generating Plant-Unit 1 Licensee Event Report 2018-001-00 Manual Reactor trip due to High Steam Generator Water Level Enclosure Unit 1 Licensee Event Report 2018-001-00

NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)

Estimated burden per response to comply w1th this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />

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Reported lessons learned are incorporated into the licensing process and fed back to

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LICENSEE EVENT REPORT (LER) industry Send comments regarding burden estimate to the Information Services Branch 1:!

n (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail c

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(See Page 2 for required number of digits/characters for each block) to lnfocollects Resource@nrc.gov, and to the Desk Officer. Office of Information and a

1:

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Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, 08 (See NUREG-1 022. R.3 for instruction and guidance for completing this fonn Washington. DC 20503 If a means used to impose an information collection does not h!:iQ./Iwww.n!J<.QQV/readlog-rrnldoc-co~tion~nur~~staff/~r1022/r30 display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection

1. Facility Name

~* Docket Number

• Page Vogtle Electric Generating Plant 05000424 1 OF2

4. Title Manual Reactor Trip due to High Steam Generator Water Level

5. Event Date

6. LER Number

7. Report Date

8. Other Facilities Involved Sequential Rev Facility Name Docket Number Month Day Year Year Number No Month Day Year N/A 05000 07 03 2018 2018

-001

-00 08 30 2018 Facility Name Docket Number N/A 05000

9. Operating Mode

11. This Report is Submitted Pursuant to the Requiremen1s of 10 CFR §: (Check all that apply) 1 0 20.2201(b) 0 20.2203(a)(3)(i) 0 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A) 0 20.2201 (d) 0 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) 181 50.73(a)(2)(iv)(A) 0 50.73(a)(2)(x)

10. Power Level 0 20.2203(a)(2)(ii) 0 50.36(c)(1 )(ii)(A) 0 50.73(a)(2)(v)(A) 0 73.71(a)(4) 100 0 20.2203(a)(2)(iii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(B)

D 73.71(a)(5) 0 20.2203(a)(2)(iv) 0 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(C)

D 73.77(a)(1) 0 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(D)

D 73.77(a)(2)(ii)

D 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B) 0 50.73(a)(2)(vii)

D 73.77(a)(2)(iii) 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

~~lephone Number (Include Area Code}

~ogtle Electric Generating Plant, Matthew Horn, Regulatory Affairs Manager 06-848-1544

13. Complete One Une for each Component Failure Described in this Report Cause System Component Manufacturer Reportable To ICES Cause System Component Manufacturer Reportable To ICES E

SN P<

X999 If N/A

14. Supplemental Report Expected Month Day Year D Yes (If yes, complete 15. Expected Submission Date) ~ No

15. Expected Submission Date N/A N/A N/A f.bstract (limit to 1400 spaces, i e., approximately 14 single-spaced typewritten lines)

~t 0954 EDT on July 3, 2018, with Unit 1 in Mode 1, 100 percent power, the reactor was manually tripped due to high

~team generator water level. The high steam generator water level was caused by a controller failure on Heater Drain Tank B which led to a feedwater oscillation on the secondary side of the plant. This oscillation caused steam generator water levels to increase. Control Room operators monitored this increase and manually tripped the plant prior to reaching the

~utomatic trip setpoint.

~he unit was stabilized in Mode 3 with decay heat removed through the main steam lines through the steam dumps and into the condenser.

~his event had no adverse effects on the health and safety of the public and is of very low safety significance. This event is reportable under 1 OCFR50. 73(a)(2)(iv)(A) due to manual actuation of systems listed in 1 OCFRSO. 73(a)(2)(iv)(B).

Unit 2 was not affected.

NRC FORM 366 (02-2018)

NRC FORM 366A (04-2018) _,.,...........

.. ~ ~

\\~/j U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-D104 EXPIRES: 3/31/2020 LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET 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.Resourte@nrt gov, and to the Desk Officer, Office ol 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 (See NUREG-1 022, R.3 for instruction and guidance for completing this form does not d splay a currently valid OMB control number, the NRC may not conduct or sponsor, and a http://WINW.nrc.gov/reading-rm/doc-colleclions/nureas/staff/sr1 022/r3D person is not required to respond to, the information collection.

1. FACILITYNAME

2. DOCKETNUMBER

3. LER NUMBER YEAR Vogtle Electric Generating Plant 05000-424 2018 NARRATIVE A. Event Description SEQUENTIAL NUMBER

• 001 REV NO

-DO On July 3, 2018 at approximately 0920 EDT, Unit 1 was in Mode 1, 100 percent power. All systems were in their normal lineup. At that time, the high-level dump controller [PMC] for the Heater Drain Tank B [TK] malfunctioned. This caused the high-level dump valve to cycle open, closed, then open again. The cycling of this valve caused a flow oscillation in the feedwater system. Due to the low Feed Pump suction pressure caused by this flow oscillation, the third condensate pump automatically started. As the third condensate pump started, the high-level dump valve closed and then sent excess water into the Steam Generators [SG]. The Control Room Operators were monitoring water levels in the Steam Generators and when the water level rose and continued to rise, they manually initiated a reactor trip/turbine trip. This initiated a Reactor Protection System actuation. The reactor was tripped at approximately 0954 EDT. Feedwater isolated and the auxiliary feedwater system automatically started and supplied water to the steam generators. Decay heat was removed via the main steam system through the steam dumps and into the condenser.

B. Cause of Event The cause of the manual plant trip was a malfunction of the controller on the Heater Drain Tank B high-level dump valve and the resulting flow oscillation caused by the repeated opening and closing of this valve coincident with the third condensate pump starting which cause an increase in steam generator water level.

C. Safety Assessment When the Control Room Operators manually initiated the trip, all systems responded as designed. Engineered Safety Features (ESF) automatic actuations for Auxiliary Feedwater, Feedwater Isolation, and Turbine Trip occurred as expected, and the control rods fully inserted into the core. Because all systems responded as required and there were no adverse effects on the health and safety of the public, the safety significance of this event is very low.

D. Corrective Actions The controller for Heater Drain Tank B was replaced and satisfactorily tested prior to being returned to service.

E.

Previous Similar Events None NRC FORM 366A (04-2018)

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