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LER-2015-008, Regarding Turbine Stop Valve Closure and Turbine Control Valve Fast Closure Reactor Protection System Functions Considered Inoperable Due to Open Turbine Bypass Valve
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor; 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)(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)
	3412015008R00 - NRC Website
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Regarding Turbine Stop Valve Closure and Turbine Control Valve Fast Closure Reactor Protection System Functions Considered Inoperable Due to Open Turbine Bypass Valve
	ML16091A472
Person / Time
Site:	Fermi
Issue date:	03/29/2016
From:	Polson K; DTE Electric Company, DTE Energy
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	NRC-16-0023 LER 15-008-00
	Download: ML16091A472 (6)
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Keith J. Poison Site Vice President DTE Energy Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.4849 Fax: 734.586.4172 Email: polsonk@dteenergy.com SDUE Enagy-March 29, 2016 10 CFR 50.73 NRC-16-0023 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C.

20555-0001 References: Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43

Subject:

Licensee Event Report (LER) No. 2015-008 Pursuant to 10 CFR 50.73 (a)(2)(v)(A), (a)(2)(v)(D), and (a)(2)(vii), DTE Electric Company (DTE) is submitting the enclosed LER No. 2015-008, Turbine Stop Valve Closure and Turbine Control Valve Fast Closure Reactor Protection System Functions Considered Inoperable Due to Open Turbine Bypass Valve.

No commitments are being made in this LER.

Should you have any questions or require additional information, please contact Mr. Alan I. Hassoun of my staff at (734) 586-4287.

Sincerely, Keith J. Polson Site Vice President Enclosure cc:

NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 5, Region III Regional Administrator, Region III Michigan Public Service Commission Regulated Energy Division (kindschl@michigan.gov)

Enclosure to NRC-16-0023 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 LER 2015-008, Turbine Stop Valve Closure and Turbine Control Valve Fast Closure Reactor Protection System Functions Considered Inoperable Due to Open Turbine Bypass Valve

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 101312018 (11-2015)

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

3. PAGE Fermi 2 05000 341 1 OF 4

4. TITLE Turbine Stop Valve Closure and Turbine Control Valve Fast Closure Reactor Protection System Functions Considered Inoperable Due to Open Turbine Bypass Valve

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NDUE A

Rv MONTH DAY YEAR N/A 05000 N/A FACILITY NAME DOCKET NUMBER 02 21 2015 2015 008 00 03 29 2016 N/A 05000 N/A

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A)

Q 20.2201(d) 20.2203(a)(3)(ii)

F 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 1 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)

E_

20.2203(a)(2)(i) 50.36(c)(1)(i)(A)

El 50.73(a)(2)(iv)(A) 50.73(a)(2)(x)

10. POWER LEVEL Q

20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A)

/

50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C) 73.77(a)(1) 100 20.2203(a)(2)(v) 50.73(a)(2)(i)(A)

/

50.73(a)(2)(v)(D) 73.77(a)(2)(i) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B)

/50.73(a)(2)(vii) 73.77(a)(2)(ii) 50.73(a)(2)(i)(C)

Q OTHER Specify in Abstract below or in NRC Form 366A

12. LICENSEE CONTACT FOR THIS LER LENSEE CONTACT TELEPHONE NUMBER (Include Area Code)

Alan I. Hassoun - Manager, Nuclear Licensing (734) 586-4287CAUSE SYSTEM COMPONENT FACTURER REPORTABLE

CAUSE

SYSTEM FACTURER U

REPORTABLE X

IT CBD E275 Y

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR SUBMISSION YES (If yes, complete 15. EXPECTED SUBMISSION DATE)

NO DAT E ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewitten lines)

At 0030 EST on February 21, 2015, while operating at 100 percent Reactor Thermal Power (RTP), the West Turbine Bypass Valve (TBV) automatically opened as expected for approximately 1 minute in response to the number two High Pressure Turbine Stop Valve (TSV) cycling from full open to closed and then to 22 percent open due to an actuator malfunction. Technical Specification (TS) 3.3.1.1 requires that the TSV closure and Turbine Control Valve (TCV) fast closure RPS functions be operable at or above 29.5 percent RTP.

Per TS Bases 3.3.1.1, TBVs must remain shut while RTP is at or above 29.5 percent to consider all channels of the TSV closure and TCV fast closure Reactor Protection System (RPS) functions operable. As a result, all channels of the TSV closure and TCV fast closure RPS functions were considered inoperable and TS 3.3.1.1 Limiting Condition of Operation (LCO) Condition 'C' was entered.

At 0031 EST the TBV automatically closed and the TSV closure and TCV fast closure RPS functions were no longer considered inoperable and the TS LCO was exited. Reactor Operators lowered RTP to 91.5 percent to isolate and restore the TSV to full open. In this event, during the period of time while the TBV was open, reactor power was maintained above 91.5 percent and the RPS functions were confirmed to be enabled. The actuator malfunction was caused by a failed comparator circuit card in the TSV valve control module. The failed comparator circuit card was replaced.

NRC FORM 366 (11-20151

Page 2 of 4U.S. NUCLEAR REGULATORY COMMISSION (11-2015)

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET

3. LER NUMBER YEAR SEQUENTIAL REV 05000-NUMBER NO.

Fermi 2 341 2015 008 00

Initial Plant Conditions

Mode 1 Reactor Power 100 percent There were no systems, structures, or components that were inoperable at the start of the event that contributed to the event.

Description of the Event At 0030 EST on February 21, 2015, while operating at 100 percent Reactor Thermal Power (RTP), the West Turbine Bypass Valve (TBV) ((V)) automatically opened as expected for approximately 1 minute in response to the number two High Pressure Turbine Stop Valve (TSV) cycling from full open to closed and then to 22 percent open due to an actuator malfunction.

Per Technical Specification (TS) Bases 3.3.1.1, TBVs must remain shut while RTP is at or above 29.5 percent to consider all channels of the TSV closure and Turbine Control Valve (TCV) fast closure Reactor Protection System (RPS) ((JD))

functions operable. As a result, all channels of the TSV closure and TCV fast closure RPS functions were considered inoperable and TS 3.3.1.1 Limiting Condition of Operation (LCO) Condition 'C' was entered.

Troubleshooting revealed that the valve actuator malfunction and TSV position cycling was caused by a failed comparator circuit card in the TSV valve control module. At 0031 EST the TBV automatically closed and the TSV closure and TCV fast closure RPS functions were no longer considered inoperable and the TS LCO was exited. Reactor Operators lowered RTP to 91.5 percent to isolate and restore the TSV to full open.

TS 3.3.1.1 requires that the TSV closure and TCV fast closure RPS functions be operable at or above 29.5 percent RTP.

An event notification and follow up notification (No. 51756) were made to the NRC based on meeting the reporting criteria of 10 CFR 50.72(b)(3)(v)(A) and (D).

This event is reportable under 10 CFR 50.73(a)(2)(v), as an event or condition that could have prevented the fulfillment of the safety function of systems that are needed to: (A) shut down the reactor and maintain it in a safe shutdown condition and (D) mitigate the consequences of an accident.

In addition, since this event affected all channels of the TSV closure and TCV fast closure RPS functions, this event is reportable under 10 CFR 50.73(a)(2)(vii), as an event where a single cause or condition caused two independent channels to become inoperable in a single system designed to: (A) shut down the reactor and maintain it in a safe shutdown condition and (D) mitigate the consequences of an accident.

There were no radiological releases associated with this event.

Page 3 of 4U.S. NUCLEAR REGULATORY COMMISSION (11-2015)

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET

3. LER NUMBER YEAR SEQUENTIAL REV

- 05000-NUMBER NO.

Fermi 2 341 207 I

205-008 00

Significant Safety Consequences and Implications

There were no significant safety consequences associated with this event. At no time during this event was there a potential for endangering the public health and safety.

Per Chapter 15 of the Fermi 2 Updated Final Safety Analysis Report (UFSAR), the TSV closure function is the primary scram signal for the turbine trip event. For this event, the reactor scram reduces the amount of energy required to be absorbed and ensures that the Minimum Critical Power Ratio (MCPR) Safety Limit (SL) is not exceeded. TSV closure signals are initiated from position switches located on each of the four TSVs. This function must be enabled at RTP greater than or equal to 29.5 percent.

Per Chapter 15 of the Fermi 2 UFSAR, the TCV fast closure function is the primary scram signal for the generator load rejection event. For this event, the reactor scram reduces the amount of energy required to be absorbed and ensures that the MCPR SL is not exceeded. TCV fast closure signals are initiated by the de-energization of the solenoid dump valve at each control valve. This function must be enabled at RTP greater than or equal to 29.5 percent.

Four Turbine First Stage Pressure (TFSP) transmitters ((PT)) are provided to initiate the automatic bypass of the TCV fast closure and TSV closure scrams, when the first stage pressure is below a preset fraction of rated pressure corresponding to approximately 29.5 percent of rated power.

The TBVs, if open at power levels above 29.5 percent RTP, may cause the TSV closure and TCV fast closure RPS functions to be inadvertently bypassed due to the diversion of steam flow away from the TFSP transmitters. In this event, during the period of time while the West TBV was open, reactor power was maintained above 91.5 percent and the RPS functions were confirmed to be enabled. Therefore, there was no actual impact on safety.

Cause of the Event

The valve actuator malfunction and TSV position cycling was caused by a failed comparator circuit card in the TSV valve control module. The comparator circuit card was incorrectly indicating a discrepancy detected state and providing an incorrect output signal to the valve control module while being supplied with correct non-discrepant input. This caused the number two TSV to cycle from full open to closed and then to 22 percent open and as expected the West TBV automatically opened.

Corrective Actions

The failed circuit card was replaced.

Additional corrective actions include: adding the failed circuit card to the Circuit Card Program, testing all turbine valve control module comparator circuit cards, and creating a new preventative maintenance event for future testing of all turbine valve control module comparator circuit cards.

Page 4 of 4U.S. NUCLEAR REGULATORY COMMISSION (11-2015)

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET

3. LER NUMBER YEAR SEQUENTIAL REV 05000-NUMBER NO.

Ferm 2 341 2015-008 00

Additional Information

A. Failed Component: Comparator Circuit Card Function: Compare Input Demand Signals to the High Pressure Turbine Stop Valve Manufacturer: English Electric Model Number: 650-30X-3154 B. Previous Licensee Event Reports (LERs) or Similar Events:

LER 2016-001 reported the TSV closure and TCV fast closure RPS functions being considered inoperable due to TBVs automatically opening. The cause of that event was a failed power amplifier circuit card in the number one TSV valve control module providing an incorrect output signal.

A review of internal Operating Experience, including the 2016 event, did not reveal a component or failure mode that could have predicted this event.