05000416/LER-2018-009, Reactor Manual Shutdown Due to Feedwater Level Control Changes

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Reactor Manual Shutdown Due to Feedwater Level Control Changes
ML18317A327
Person / Time
Site: Grand Gulf Entergy icon.png
Issue date: 11/13/2018
From: Emily Larson
Entergy Operations
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
GNRO-2018/00053 LER 2018-009-00
Download: ML18317A327 (6)
v • d • e


LER-2018-009, Reactor Manual Shutdown Due to Feedwater Level Control Changes
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
10 CFR 50.73(a)(2)(ix)(A)
10 CFR 50.73(a)(2)(x)
10 CFR 50.73(a)(2)(iv)(A), System Actuation
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)(v), Loss of Safety Function
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)
10 CFR 50.73(a)(2)(viii)(A)
10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded
10 CFR 50.73(a)(2)(viii)(B)
10 CFR 50.73(a)(2)(iv)(B), System Actuation
4162018009R00 - NRC Website
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text

GNR0-2018/00053 November 13, 2018 U.S. Nuclear Regulatory Commission

. Attn: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Licensee Event Report 2018-009-00,

. Entergy Operations, Inc.

P. 0. Box 756 Port Gibson, MS 39.150 Eric A. Larson Site Vice President Grand Gulf Nuclear Station Tel. (601) 437-7500 10CFR50.73

. Reactor Manual Shutdown Due to Feedwater Level Control Changes Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29

Dear Sir or Madam:

Attached is Licensee Event Report 2018-:-009-00 Reactor Manual Shutdown Due to Feedwater Level Control Changes. This report is being submitted in accordance with 1 OCFR50. 73(a)(2)(iv)(A) as an event or condition that resulted in an unplanned manual actuation of the reactor protection system.

/

This letter contains no new commitments. If you have any questions or require additional intormation, please contact Douglas Neve at 601-437-2103.

. Eric A. Larson EAUdre

Attachment:

Licensee Event Report 2018-009-00 cc: see next page

GNR0-2018/00053 Page 2 of 2 cc:

NRC S~nior Resident Inspector Grand Gulf Nuclear Station

  • Port Gibson, MS 39150 U.S. Nuclear Regulatory Commission ATTN: Ms. Lisa M. Regner Mail Stop OWFN 8 81 Rockville, MD* 20852-2738 U.S. Nuclear Regulatory Commission ATTN: Mr. Kriss Kennedy, NRR/DORL (w2)

Regional Administrator, Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 I

G N R0-2018/00053 Attachment Licensee Event Report 2018-009~00

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (06-2016)

, the NRG rnay not conduct or sponsor, and a person is

"> ***** ~

not required to respon(:l to, the information collection.

13. PAGE Grand Gulf Nuclear Station, Unit 1
  • 05000 :l16.

1 OF3 I

4. TITLE Reactor Manual Shutdown Due to Feedwat.er Level Control Changes
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 NUMBER NO.

MONTH DAY YEAR N/A 05000 N/A FACILITY NAME DOCKET NUMBER

09.

14 2018.

2018-009-00 11 13 2018 N/A 05000 N/A

9. OPERATING MODE
11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)

D 20.2201 (b)

D 20.2203(a)(3)(ii)

D 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(ix)(A)

MODE1 D 20.2201 (d)

D 20.2203(a)(4)

D so.13(a)(2)(iiir D 50.73(a)(2)(x)

D 20.2203(a)(1)

D 50.36(c)(1 )(i)(A)

~ 50.73(a)(2)(iv)(A)

D 73.11 (a)(4)

D 20.2203(a)(2)(i)

D 50.36(c)(1 )(ii)(A)

D 50.73(a)(2)(v)(A)

D 73.11 (a)(s)

' *~;.

10. POWER LEVEL D 20.2203(a)(2)(ii)

D so.36(c)(2)

D 50.73(a)(2)(v)(B)

D 73.11(a)(1)

D 20.2203(a)(2)(iii)

D so.46(a)(3)(ii)

D 50.73(a)(2)(v)(C)

  • D 73. 11(a)(2)(i) 100%

D 20.2203(a)(2)(iv)

D 50.73(a)(2)(i)(A)

D 50.i3(a)(2)(v)(D)

D 73. 11(a)(2)(ii)

D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(B)

D 50.73(a)(2)(vii)

D OTHER

- D 20.2203(a)(2)(vi)

D 50.73(a)(2)(i)(C)

D 50.73(a)(2)(viii)(A)

Specify in Abstract below D 20.2203(a)(3)(i)

D 50.73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(B) or in =

A. PLANT CONDITIONS PRIOR TO THE EVENT

3. LER NUMBER SEQUENTIAL NUMBER 2018-009-00 Grand Gulf Nuclear Station (GGNS) Unit 1 was operating at approximately 100 percent power in Mode 1. The 6A feedwater heater level dump valve was in manual control. The 6A feedwater heater drain valve was in automatic control.

B. DESCRIPTION

At 1638 hours0.019 days <br />0.455 hours <br />0.00271 weeks <br />6.23259e-4 months <br /> CDT on September 14, 2018, while the plant was operating at approximately 100 percent reactor power, maintenance technicians were performing a backfill of the 6A feedwater [SJ] heater level tra*nsmitter 1 N23N059A [JB]. The transmitter was taken out of service in the control logic, but it continued to provide backup input to the drain valve controller.

When the backfill procedure was performed, the control system.swapped controlling level tran*smitters from normal to backup. This caused the 6A feedwater heater drain valve to open resulting in increased flow to the heater drain tank. This system transient, coupled with inadequate tuning of the heater drain tank level controller, resulted in oscillations of the heater drain tank level control valves.

The above condition resulted in increased demand on the condensate system and eventually in low suction pressure for the condensate booster and reactor feedwater pumps. One condensate booster pump automatically tripped on low suction pressure followed by a trip of one reactor feedwater pump on low suction pressure.

The feed pump trip initiated a reactor recirculation [AD] flow control. valve runback signal.

At 16:44 hours on September 14, 2018, operators performed a manual reactor protection system shutdown of the reactor. Upon reactor shutdown all systems performed as designed and no subsequent safety system actuations occurred.

C. REPORTABILITY

This report is made pursuant to 1 OCFR50.73(a)(2)(iv)(A) for any event or condition that resulted in a. manual or automatic actuation of the reactor protection system as listed in 1 OCFR50.73(a)(2)(iv)(B).

This event was reported under 1 OCFR50.72(b)(2)(iv){B) for any event that results in the actuation of the reactor protection system while. the reactor is critical in ENS notification 53608.

Page2of3 REV.

NO.

NRC FORM (6-2016) 366AU-.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET

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

  • 1_. FACILITY NAME
2. DOCKET Grand Gulf Nuclear Station, Unit 1 05000 416

D. CAUSE

YEAR

3. LER NUMBER SEQUENTIAL NUMBER 2018-009-00 The cause evaluation is in progress. A supplemental LER will be submitted if the results of the cause evaluation warrant.
  • The cause of the manual shutdown was operator response in anticipation of reactor water level lowering to the reactor vessel water level 11.4 inch scram setpoint, caused by a reduction in feedwater system flow to the reactor vessel.

REV.*

NO.

The direct cause of the event was an incorrectly tuned heater drain tank level control system circuit.

E. CORRECTIVE ACTIONS

The following corrective actions are completed or proposed.

Completed:

Control circuits for the heater drain tank level control system have been adjusted.

Proposed action in the corrective action program, which may be changed in accordance with the program when the cause evaluation is complete:

Changes to the procedure governing post modification testing.

F. SAFETY SIGNIFICANCE

The safety significance of this event is determined to be low. The manual scram was performed in accordance with plant procedures. There were no actual nuclear safety consequences or radiological consequences during the event.

G. PREVIOUS SIMILAR EVENTS

Entergy conducted a three-year review of the relevant licensee event reports and determined that there was one similar known event reported as GGNS Licensee Event Report 2018-01-00 Reactor Manual Shutdown due to Turbine Pressure Control Valve Position Changes. The failure in that event was an incorrect setting in one element of a three element turbine control anti-resonance circuit, which is different from this event which is likely a control circuit tuning issue. Therefore, the corrective actions for the previous event would not have prevented this event.

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