05000249/LER-2015-001

LER-2015-001, Main Steam Line Flow Switches Found Outside Tech Spec Allowed Value

Dresden Nuclear Power Station, Unit 3
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2492015001R00 - NRC Website

LER 15-001-01, Dresden, Unit 3 Main Steam Line Flow Switched Found Outside Tech Spec Allowed Value

ML16028A195
Person / Time
Site:	Dresden
Issue date:	01/22/2016
From:	Washko J Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SVPLTR# 16-0005 LER 15-001-01
Download: ML16028A195 (4)

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PLANT AND SYSTEM IDENTIFICATION

Dresden Nuclear Power Station (DNPS), Unit 3, is a General Electric Company Boiling Water Reactor with a licensed maximum power level of 2957 megawatts thermal. The Energy Industry Identification System codes used in the text are identified as [XX].

Plant Conditions Prior to Event:

Unit: 03 Reactor Mode: 1 Event Date: 09/05/15 to 09/11/15 Event Time: 1100 CDT Mode Name: Power Operation Power Level: 100 percent

Description of Event:

During quarterly calibration and functional testing of Main Steam [SB] Line High Flow switches, two switches were found to not meet surveillance requirements of Technical Specification 3.3.6.1. This event is being reported under 10 CFR 50.73(a)(2)(i)(B) "Operation or Condition Prohibited by Technical Specifications" due to multiple test failures of similar components.

Additionally, at approximately 1100 CDT on September 5, 2015, Operations logged the failure of a switch to meet SR 3.3.6.1.1 channel check criteria. September 7, 2015, TS 3.3.6.1 Condition A and D completion times had not been met and Tech Spec 3.0.2 was entered. Maintenance personnel repaired the affected instrument. This event is being reported under 10 CFR 50.73(a)(2)(i)(B) "Any operation or condition which was prohibited by the plant's Technical Specifications...".

No individual failure caused a loss of safety function. The aggregate impact of these events did not result in the loss of safety function.

Cause of Event:

The cause of these issues is under investigation.

D. Safety Analysis:

The automatic isolation closure of the main steam line isolation valves was maintained due to system redundancy. No loss of safety function occurred, therefore these failures are considered of very low safety significance. Further safety analysis will be completed by the investigation.

E. Corrective Actions:

Immediate corrective actions included replacement of the failed components and remediation of the Operations team which failed to identify the Tech Spec condition. Further corrective actions will be determined through the open investigation.

F. Previous Occurrences:

A review of the previous 12 quarterly surveillances, three years, was performed. No previous occurrences were identified. Further occurrences will be determined through the corrective action program.

G. Component Failure Data:

Manufacturer Model S/N Type ITT Barton 288A and 289A TBD Meter Movement for Differential pressure switch