05000346/LER-2020-001, Three Main Steam Safety Valves Failed Inservice Test Program As-Found Lift Acceptance Criteria
| ML20132A112 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 04/20/2020 |
| From: | Bezilla M Energy Harbor Nuclear Corp |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| L-20-103 LER 2020-001-00 | |
| Download: ML20132A112 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(x) 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)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 3462020001R00 - NRC Website | |
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1111B energy
~harbor Mark B. Bezilla Site Vice President, Davis-Besse Nuclear April 20, 2020 L-20-103 A TIN: Document Control Desk United States Nuclear Regulatory Commission Washington, D.C. 20555-0001
Subject:
Davis-Besse Nuclear Power Station, Unit 1 Docket Number 50-346, License Number NPF-3 Licensee Event Report 2020-001 Davis-Besse Nuclear Power Station 5501 N. State Route 2 Oak Harbor, Ohio 43449 419-321-7676 10 CFR 50.73 Enclosed is Licensee Event Report (LER) 2020-001-00, "Three Main Steam Safety Valves Failed lnservice Test Program As-Found Lift Acceptance Criteria." This event is being reported pursuant to 10 CFR 50.73(a)(2)(i)(B).
There are no regulatory commitments contained in this letter or its enclosure. The actions described represent intended or planned actions and are described for information only. If there are any questions or if additional information is required, please contact Mr. James M. Vetter, Manager - Regulatory Compliance and Emergency Response, at (419) 321-7393.
Sincerely, f!!f:~ rJtl GMW Enclosure: LER 2020-001 cc: NRC Region Ill Administrator NRC Resident Inspector NRR Project Manager Utility Radiological Safety Board
N-RC-FbRM 366 U.S. NUCLEARREGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 4/30/2020 (04-2020) 3.Page Davis-Besse Nuclear Power Station, Unit 1 05000 346 1 OF 3
- 4. Title:
Three Main Steam Safety Valves Failed lnservice Test Program As-Found Lift Acceptance Criteria
- 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 05000 Facility Name Docket Number-02 26 2020 2020 -
001 -
00 04 20 2020 05000
- 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)(i)
D 50. 73(a)(2)(ii)(A)
D 50. 73(a)(2)(viii)(A) 1 D 20.2201(d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(B)
D 50. 73(a)(2)(viii)(B)
D 20.2203(a)(1)
D 20.2203(8)(4)
D 50.73(a)(2)(iii)
D 50. 73(a)(2)(ix)(A)
D 20.2203(a)(2)(i)
D 50.36(c)(1)(i)(A)
D 50. 73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
- 10. Power Level D 20.2203(a)(2)(ii)
D 50.36(c)(1)(ii)(A)
D 50.73(a)(2)(v)(A)
D 73.71 (a)(4)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(B)
D 73. 71 (a)(5)
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(C)
D 73.77(a)(1) 74 D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi)
~ 50. 73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 73.77(a)(2)(ii)
- - D 50.73(a)(2)(i)(C)
D Other (Specify in Abstract below or in =
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
System Description
001 The Main Steam System [SB] at the Davis-Besse Nuclear Power Station (DBNPS) contains nine Main Steam Safety Valves (MSSVs) [SB-RV] on each of the two Main Steam headers. The MSSV rated capacity is approximately 115 percent of the total secondary system design flow to meet the requirements of Section Ill of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code. This ensures the secondary system pressure is limited to less than or equal to 110 percent of design pressure when passing 100 percent 9f design steam flow.
Technical Specifications:
00 Technical Specification (TS) Limiting Condition for Operation {LCO) requires the MSSVs be Operable while in Modes 1, 2, and 3. With one or more MSSVs inoperable, Condition A requires reactor power be reduced within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and the High Flux Trip setpoint be reduced within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> based on the operable MSSV relieving capacity. If the required action of Condition A and associated Completion Time are not met, or one or more Steam Generators [AB-SG] have less than two MSSVs operable, or one or more Steam Generators have no MSSV with a lift setting of 1050 psig operable, then Condition B requires the unit to be in Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 4 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. TS Surveillance Requirement 3. 7.1.1 requires verification of each MSSV lift setpoint per TS Table 3.7.1-1 in accordance with the lnservice Testing Program, and following testing, lift settings shall be within +/- 1 percent of the setpoint. Table 3. 7.1-1 specifies 2 MSSVs per Steam Generator have a lift setting of 1050 psig +/- 3 percent, and 7 MSSVs per Steam Generator valves have a lift setting of 1100 psig +/- 3 percent.
DESCRIPTION OF EVENT
On February 26, 2020, with the DBNPS operating at approximately 74 percent power for the end of fuel cycle coast down, scheduled MSSV setpoint testing was conducted in accordance with the lnservice Test Program.
The initial testing scope was to in-place test eight of the 18 installed MSSVs. During testing that completed February 27, 2020, the following three valves lifted outside their required as-found setpoint by more than three percent:
Valve Number SP17B9 SP17A5 SP17A2 Desired Setpoint (psig) 1100 1100 1100 As-Found Setpoint 1066.6 1060.4 1049.6 Offset (percent)
- - 3.04
- - 3.60
- - 4.58 Each valve lifting outside the required as-found setpoint was adjusted and retested to within the as-left acceptance criteria of two c_onsecutive lifts within +/- one percent of the setpoint, or between 1089 and 1111 psig. In accordance with the lnservice Test Program, two additional valves with the same setpoint (1100 psig) were tested for each valve failure; all six of the additional valves in the expanded scope lifted within the required as-found range.
CAUSE OF EVENT
- 2. DOCKET NUMBER 346 YEAR 2020
- 3. LER NUMBER SEQUENTIAL NUMBER 001 The cause of this event is under evaluation and will be provided in a revision to this Licensee Event Report.
ANALYSIS OF EVENT
REV NO.
00 The primary purpose of the MSSVs is to provide overpressure protection for the secondary system. The MSSVs also provide protection against overpressurizing the reactor coolant pressure boundary by providing a heat sink for removal of energy from the Reactor Coolant System [AB] if the preferred heat sink, provided by the Condenser [SG-COND] and Circulating Water System [KE], is not available. With the MSSVs lifting prior to their established lift settings, the ability of the MSSVs to provide overpressure protection was not adversely impacted. Therefore, there was no loss of safety function for the MSSVs, and this issue is considered to be of very low safety significance.
Reportability Discussion:
The existence of similar discrepancies in multiple valves is an indication that the discrepancies arose over a period of time. Therefore, it is assumed the plant operated with these three MSSVs inoperable without taking the actions specified in Technical Specification 3.7.1. In accordance with the guidance contained in NUREG-1022, Event Reporting Guidelines for 10 CFR 50.72 and 50.73, Revision 3, this condition represents operation of the plant in a condition that is prohibited by the plant's Technical Specifications, and is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B).
CORRECTIVE ACTIONS
Completed Actions:
Upon discovery of an individual valve's setpoint being outside of the allowable value, the valve was declared inoperable until the setpoint was adjusted to be within the allowable value. Reactor Power had been reduced in accordance with Technical Specification 3. 7.1 Action A for one MSSV per Steam Generator to be inoperable prior to the start of testing.
Scheduled Actions:
Because the cause of this issue is still under evaluation, additional corrective actions will be provided in a revision to this Licensee Event Report.
PREVIOUS SIMILAR EVENTS
There have been no Licensee Event Reports {LERs) at the DBNPS in the past three years related to the MSSVs. Page 3 of 3