05000390/LER-2017-001, Cancellation of Licensee Event Report 390/2017-001 Related to Essential Raw Cooling Water Pump Reverse Rotation Keys Representing a Potential Common Cause Lnoperability
| ML17046A220 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 02/14/2017 |
| From: | Simmons P Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 17-001-00 | |
| Download: ML17046A220 (2) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability |
| 3902017001R00 - NRC Website | |
text
Tennessee Valley Authority, P.O. Box 2000 Spring City, Tennessee 37381 Febru ary 14, 2017 ATTN. Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001
Subject:
Reference:
10 cFR 50 73 Watts Bar Nuclear Plant, Units 1 and2 Facility Operating License Nos. NPF-90 and NPF-96 NRC Docket Nos. 50-390 and 50-391 Cancellation of Licensee Event Report 39012017-001 Related to Essentia!
Raw Cooling Water Pump Reverse Rotation Keys Representing a Potential Common Cause lnoperability Letter from TVA to NRC, "Licensee Event Report 39012017-001, Failure of Emergency Raw Cooling Water Pump Reverse Rotation Keys Represents Potential Common Cause lnoperability," dated January 9,2017 On January 9,2017, the Tennessee Valley Authority (TVA) submitted Licensee Event Report (LER) 39012017-0Ol related to Essential Raw Cooling Water (ERCW) pump reverse rotation keys representing a potential common cause inoperability in accordance with 10 CFR 50.73(a)(2)(vii). This letter is being submitted to cancel (formally withdraw) LER 390/2017-001, consistent with the guidance of NUREG-1022, Revision 3, Sections 2.8 and 5.1.2.
The LER described an issue with the ERCW non-reverse rotation clutch where a number of failures of the clutch keys had occurred in the recent past. The non-reverse clutch prevents the ERCW pump from rotating in the reverse direction after pump trip, which could cause the motor to develop a higher than normal in-rush current if the motor was subsequently started, such as following an accident.
TVA has completed detailed analyses documented in a past operability evaluation to determine if a motor trip would occur if the ERCW pump non-reverse clutch had failed, and the pump was subsequently restarted while turning in the reverse direction. Models were developed and benchmarked against plant data to ensure accuracy. The result is that assuming a subsequent motor start while the ERCW pump was rotating at the highest predicted reverse rotational speed, a motor trip on high current would not occur. Based on these analyses, there is no potential for non-reverse clutch key failures to cause inoperability of the ERCW pumps.
U.S. Nuclear Regulatory Commission Page2 February 14,2017 Therefore, TVA has concluded WBN did not have a potential common cause inoperability of the ERCW system and this condition is not reportable under 10 CFR 50.73(aX2)(vii). LER 39012017-001 is being cancelled, and the LER No. 2017-001will not be reused for Docket No.
50-390. This LER also reported that a supplemental LER was anticipated. This cancellation eliminates the need for that supplement.
There are no regulatory commitments contained in this letter. Should you have questions regarding this cancellation, please contact G. P. Arent, Licensing Director, at (423) 365-2004.
Respectfully, Paul Simmons Site Vice President Watts Bar Nuclear Plant cc:
NRC Regional Administrator - Region ll NRC Senior Resident lnspector - Watts Bar Nuclear Plant