05000334/LER-2006-001, Re Main Steam Safety Valve Relief Tests Exceeded Technical Specification Required Setpoint Tolerance

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Re Main Steam Safety Valve Relief Tests Exceeded Technical Specification Required Setpoint Tolerance
ML061020305
Person / Time
Site: Beaver Valley
Issue date: 04/10/2006
From: Lash J
FirstEnergy Nuclear Operating Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
L-06-047 LER 06-001-00
Download: ML061020305 (7)
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LER-2006-001, Re Main Steam Safety Valve Relief Tests Exceeded Technical Specification Required Setpoint Tolerance
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
10 CFR 50.73(a)(2)(i)
10 CFR 50.73(a)(2)(viii)(A)
10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
10 CFR 50.73(a)(2)(iii)
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)(i)(A), Completion of TS Shutdown
10 CFR 50.73(a)(2)(v), Loss of Safety Function
3342006001R00 - NRC Website
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text

FENOCF FrstEnergy Nuclear Operating Company James H. Las/

Site Vice President 724-682-5234 Fax: 724-643-8069 April 10, 2006 L-06-047 Beaver Vallej Powver Station, Unit No. I Docket No. 50-334 License No. DPR-66 LER 2006-001-00 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 The following Licensee Event Report is submitted:

LER 2006-001-00, 10 CFR 50.73(a)(2)(i)(B), "Main Steam Safety Valve Relief

'Pests Exceeded Technical Specification Required Setpoint Tolerance."

Attachment c:

Mr. T. G. Colburn, NRR Senior Project Manager Mr. P. C. Cataldo, NRC Senior Resident Inspector Mr. S. J. Collins, NRC Region I Administrator INPO Records Center (via electronic image)

Mr. L. E. Ryan (BRP/DEP) 7---

NRC FORM 3E6 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 6/3012007 (6.2004)

Estimated burden per response to comply with this mandatory collection EVENT REPORT request: 50 hrs.

Reported lessons learned are incorpor.ited Into the LICENSEE EV N E O T(LER) liceunsing process and fed back to Industry. Send comments re~arding burden estimate to the Records and FOlA/Privacy Service Branch (1-5 F52), U.S.

Nuclear Regulatory Commission, Washington, DC 20555-0001, or by Internet e-mail to infocollectslnrcgov, and to the Desk Officer, Office of Information (See reverse for required number of and Regulatory Affairs. NEOB-10202 (3150-0104). Office of Maiagement and dgtthrcesfor each block)

Budget, Washington. DC 20503. If a means used to Impose -in Information digits/characters collection does not display a currentiy valid MB control number, the NRC may not conduct or sponsor, and a person Is not required to respond to, the Information collection.

3. PAGE Beaver Valley Power Station Unit Number 1 05000334 1 OF 3l
4. TITLE Main Steam Safety Valve Relief Tests Exceeded Technical Specification Required Setpoint Tolerance
5. EVENT D ATE
6. LER NUMBER
7. REPORT DATE
8. OTHER FACILITIES INVOLVED SEQUENTIAL REV 1 FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.

MONTH DAY YEAR None 12 2006 2006 001 00 04 10 2006 FACILITY NAME DOCIKET NUMBER

9. OPERATING MODE 1 1. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check ali that apply)

D 20.2201(b)

E 20.2203(a)(3)(i)

E 50.73(a)(2)(i)(C)

D 50.73(a)(21(vii) 1

] 20.2201(d)

D 20.2203(a)(3)(ii) 5 50-73(a)(2)(ii)(a) a 50.73(a)(2)(viii)(A)

D 20.2203(a)(1) a 20.2203(a)(4)

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

El 50.73(a)(2:(viii)(B)

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

E 50.73(a)(2)(iii) a 50.73(a)(2 (ix)(A)

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

E 50.36(c)(1)(ii)(A)

E] 50.73(a)(2)(iv)(A)

El 50.73(a)(2,(x) 5 20.2203(a)(2)(iii)

D 50.36(c)(2) al 50.73(a)(2)(v)(A)

D-73.71(a)(4, 60 D 20.2203(a)(2)(iv) a 50.46(a)(3)(ii) a 50.73(a)(2)(v)(B)

Ea 73.71 (a)(5, E 20.2203(a)(2)(v) 5 50.73(a)(2)(i)(A)

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

E OTHER Specify in Abstract below a

20.2203(a)(2)(vi) s 50.73(a)(2)(i)(B)

E 50.73(a)(2)(v)(D) or in

Abstract

On February 12, 2006, Beaver Valley Power Station (BVPS) Unit No. 1 performed periodic Trevitesting on the Main Steain Safety Valves (MSSVs) just prior to entering its 1 Ri7 refueling shutdown. All of the UC" Main Steam System header Main Steam Safety Valves [SV-1 MS-1 01 C, 102C,103C, 104C and 105C], which were new valves that had been installed as replacements during the previous BVPS Unit No. 1 refueling (1 R16), did not meet EVPS Unit No. 1 Technical Specification 3.7.1.1 acceptance criteria (+1 percent/-3 percent) for as-found lift pressures. The ten MSSVs associated with the "A" and "B" steam headers, which are original plant valves, all successfully passed the testing.

The root cause of the high initial lift setpoint was oxide bonding between the discs and nozzles of the new MSSVs with 422 Stainless Steel discs installed during the previous refueling outage. This material is susceptible to the oxide bonding phenomenon.

This event is reportable pursuant to 10 CFR 50.73(a)(2)(i)(B) due to the assumption that the plant inadvertently operated with multiple MSSVs inoperable due to set points outside of their required lift setting tolerance band, without taking the actions specified in Technical Specification 3.7.1.1. The affected MSSVs will be removed and replaced with safety valves that have improved pre-oxidized Inconel X-750 discs and passivated nozzles.

The risk due to the five MSSVs lifting slightly above their Technical Specification setpoint was determined to be of very low safety significance.

NRC FORM 366 (6-2004)

NRC FORM 3436A U.S. NUCLEAR REGULATORY COMMISSION (1-2001)

LICENSEE EVENT REPORT (LER)

1. FACILITY NAME
2. DOCKET
6. LER NUMBER
3. PAGE I

SEQUENTIAL REVISION YEAR NUMBER NUMBER Beaver Valley Power Station Unit Number 1 05000334 2 OF 6 2006 001 00

17. NARRATW'E (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A)

DESCRIPTION OF EVENT (Continued)

The following provides the setpoint values found and the actions taken for the five "C" steam header IMSSVs:

[SV-1M'S-101C] - Setpoint is 1075 psig +1/-3% (1042.8 to 1085.7 psig). The initial astound lift pressure was 1115.4 psig (3.8% above set pressure) and the second as-found lift pressure was 1047.7 psig (2.6% below set pressure). The valve was adjusted and re-ested until 2 consecutive lifts within +1/-1% of set pressure were achieved. The final as-left [ft pressures were 1067.7 psig and 1073.5 psig.

[SV-1 MS-1 02C] - Setpoint is 1085 psig +1/-3% (1052.5 to 1095.8 psig). The initial as-found lift pressure was 1134.5 psig (4.6% above set pressure). The second and third as-found lift pressures were 1074.9 psig (0.9% below set pressure) and 1074.5 psig (0.98% below set pressure) respectively. Thus this valve did not require adjustment to achieve 2 consecutive lifts within +1/-1% of set pressure.

[SV-1 M;-i 03C] - Setpoint is 1095 psig +1/-3% (1062.2 to 1105.9 psig). The initial as-found lift pressure was 1158.1 psig (5.8% above set pressure) and the second as-found lift pressure was 1078.6 psig (1.5% below set pressure). The valve was adjusted and re-tested until 2 consecutive lifts within +1/-1% of set pressure were achieved. The final as-left lift pressures were 1091.1 psig and 1091.7 psig.

[SV-1 M;-i 04C] - Setpoint is 1110 psig +1/-3% (1076.7 to 1121.1 psig). The initial as-found lift pressure was 1153.4 psig (3.9% above set pressure) and the second as-found lift pressure was 1091.9 psig (1.6% below set pressure). The valve was adjusted and re-tested until 2 consecutive lifts within +1/-1% of set pressure were achieved. The final as-left lift pressures were 1115.3 psig and 1114.5 psig.

[SV-1 MS-1 05C] - Setpoint is 1125 psig +1/-3% (1091.3 to 1136.2 psig). The initial as-found lift pressure was 1169.7 psig (3.97% above set pressure). The second and third as-found lift pressures were 1117.8 psig (0.6% below set pressure) and 1120.1 psig (0.4% below set pressure) respectively. Thus this valve did not require adjustment to achieve 2 consecutive lifts within +1/-1% of set pressure.

CAUSE OF EVENT

The root cause of the high initial lift setpoint has been determined to be oxide bonding between the discs and nozzles of the new MSSVs with 422 Stainless Steel (SS) discs installed during the previous refueling outage 1 R1 6. This material is susceptible to the oxide bonding phenomenon during long continuous runs of plant operation.

NRC FORM 3156A U.S. NUCLEAR REGULATORY COMMISSION (1.2001)

LICENSEE EVENT REPORT (LER)

1. FACILITY NAME
2. DOCKET
6. LER NUMBER
3. PAGE SEQUENTIAL REVISION YEA NUMBER NUMBER Beaver Valley Power Station Unit Number 1 05000334 4 OF 6 2006 001 00
17. NARRATIIE (If more space is required, use additional copies of NRC Forn 366A)

REPORTABILITY

The existence of similar discrepancies believed to be due to oxide bonding between the discs and nozzles of the new MSSVs installed during 1 R1 6 is an indication that the condition likely developed during the Unit 1 Cycle 17 operating cycle and that the condition existed prior to the surveillance testing. Thus, this event is reportable pursuant to 10 CF:R 50.73(a)(2)(i)(B) due to the assumption that the plant inadvertently operated with multiple MSSVs inoperable due to set points outside of their required lift setting tolerance band, without taking the actions specified in Technical Specification 3.7.1.1.

SAFETY IMPLICATIONS The primary purpose of the MSSVs is to provide overpressure protection for the secondary system. These valves also provide protection against over-pressurizing the reactor coolant system pressure boundary by providing a heat sink for the removal of energy from the reactor coolant system if other preferred heat sink methods (i.e., the condenser or atmospheric steam dump valves) are not available. The MSSVs also serve as containment isolation valves.

The risk significance of the BVPS Unit No. 1 "C" Steam Generator MSSVs all lifting above their setpoint tolerance of +1% is considered to be of very low risk significance, given that the remaining MSSVs on the "A" and "B" Steam Generators were within tolerance. This is based oln an Engineering evaluation of the consequences of the identified higher safety valve setpoints. This evaluation performed a review of the Westinghouse analyses for the BVPS Unit No. 1 design basis accidents which credit Main Steam Safety Safety Valve operation. These accidents include the Large Loss of External Load with Turbine Trip (Load Rejection) and Small Break Loss of Coolant Accident (SBLOCA), which are the limiting transients. Assessments against the analyses of record indicate that the existing input conservatisms in both calculations are sufficient to offset the effect of the MSSVs lifting above their Technical Specification 3.7.1.1 nominal setpoint to the extent experienced on February 12, 2006. These conservatisms include 1) an assumed 3%

tolerance for MSSV opening (for all valves in the Load Rejection and all except the first MSSV in the LOCA), 2) a 5 psi valve accumulation on all MSSVs, and 3), for the SBLOCA, a conservative Moderator Temperature and Doppler coefficients, along with a conservative High Head Safety Injection flow. While the MSSV with the lowest setpoint has a direct impact on the SBLOCA transient behavior, the valve capacity does not, because the heat load on the valve is small in comparison to its design capacity.

Therefore, only one out of the three first MSSVs and its associated Steam Generator is required to effectively dictate early transient Reactor Coolant System conditions during the SBLOCA.

NRC FORM 336A U.S. NUCLEAR REGULATORY COMMISSION (1.2001)

LICENSEE EVENT REPORT (LER)

1. FACILITY NAME
2. DOCKET
6. LER NUMBER
3. IAGE SEQUENTIAL REVISION YEAR NUMBER NUMBER Beaver Valley Power Station Unit Number 1 05000334 5 OF 6 2006 001 00
17. NARRATVIE (If more space is required, use additional copies of NRC Form 366A)

SAFETY IMPLICATIONS (Continued)

As a result of the assessments against the analyses of record, it is concluded that even with the "C" Steam Generator MSSVs all lifting above their setpoint tolerance to the extent described earlier, the peak secondary pressure in the Load Rejection would remain below the 11 0'Vo limit, while peak clad temperature in the SBLOCA would remain below 2200 OF.

In the risk assessment, since all MSSVs were available on the "A" and "B" Steam Generators at their Technical Specification setpoints, along with the Atmospheric Steam Dump Valves, and Residual Heat Release Valve, there is a high likelihood that the secondary and primary pressure boundary would be maintained during all transient conditions. Additionally, since the tested MSSVs properly reseated following their Trevitesting, the probability of them not reseating would not be increased over the current values assumed in the PRA model. Therefore, the impact on risk is considered to be very low.

CORRECTIVE ACTIONS

1. Immediate actions included adjusting SV-1 MS-1 01 C, 103C and 1 04C to within +/-1 % of their required set lift pressure.
2. The 'C" steam header MSSVs, SV-1MS101C, 102C, 103C, 104C, and 105C, will be removed and replaced with safety valves that have improved pre-oxidized Inconel X-750 discs and passivated nozzles during this 1 R1 7 refueling shutdown.
3. An action plan will be developed to perform mid-cycle testing of one MSSV on the "C" Main Steam System.
4. The Engineering Change process will be revised to enhance the integration of Operating Experience Program requirements.
5. An Operating Experience report on this subject will be issued to the industry.

Completion of the above and other corrective actions are being tracked through the BVPS corrective action program.

PREVIOUS SIMILAR EVENTS

A review found no prior BVPS Unit 1 and no prior BVPS Unit 2 Licensee Event Reports, within the last five years involving a steam generator safety valve problem.

NRC FORM 316A U.S. NUCLEAR REGULATORY COMMISSION (1-2001) 0 X

LICENSEE EVENT REPORT (LER)

1. FACILITY NAME
2. DOCKET
6. LER NUMBER
3. PAGE SEQUENTIAL REVISION YEAR NUMBER NUMBER Beaver Vail y Power Station Unit Number 1 05000334 6OF6 2006 001 00
17. NARRATIWE (If more space is required, use additional copies of NRC Form 366A)

COMMITMENTS

There are no new commitments made by FirstEnergy Nuclear Operating Company (FENOC:) for BVPS Unit No. 1 in this document.

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