05000369/LER-2016-001, Regarding Degraded Condition Due to Rejectable Flaw on U1 Charging Line
| ML16153A233 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 05/23/2016 |
| From: | Capps S Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| MNS-16-040 LER 16-001-00 | |
| Download: ML16153A233 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded |
| 3692016001R00 - NRC Website | |
text
ef_-,DUKE
~ ENERGY.
Serial No: MNS-16-040 May 23, 2016 U.S. Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, D.C. 20555
Subject:
Duke Energy Carolinas, LLC McGuire Nuclear Station (MNS), Unit 1 Steven D. Capps Vice President McGuire Nuclear Station Duke Energy MG01VP 112700 Hagers Ferry Road Huntersville, NC 27078 o: 980.875.4805 f: 980.875.4809 Steven.Capps@duke-energy.com 10 CFR 50.73 Docket No. 50-369, Renewed License No. NPF-9 Licensee !;vent Report 369/2016-01, Revision 0 Nuclear Condition Report (NCR) 2013556 Pursuant to 10 CFR 50. 73 Sections (a)(1) and (d), attached is Licensee Event Report (LER) 369/2016-01, Revision 0, regarding an American Society of Mechanical Engineers (ASME)Section XI rejectable flaw discovered on the MNS Unit 1 Chemical and Volume Control System (NV) charging piping.
This report is being submitted in accordance with 10 CFR 50. 73(a)(2)(ii)(A), a degradation of a principal safety barrier. This event is considered to be of no significance with respect to the health and safety of the public.
This LER is preliminary and will be supplemented upon completion of the cause analysis.
Duke Energy will provide a supplement to this LER within 60 days. There are no regulatory commitments contained in this LER.
If questions arise regarding this LER, please contact George Murphy of Regulatory Affairs at 980-875-5715.
Sincerely, JIO~
Steven D. Capps Attachment
U.S. Nuclear Regulatory Commission May 23, 2016 Page 2 cc:
Catherine Haney Administrator, Region II U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Ave.
NE Suite 1200, 30303-1257 G. E. Miller Project Manager (McGuire)
U.S. Nuclear Regulatory Commission 11555 Rockville Pike
- Rockville, MD 20852-2738 Mail Stop 0-8 G9A V. Sreenivas Project Manager (McGuire)
U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852-2738 Mail Stop 0-8 G9A J. Zeiler NRC Senior Resident Inspector McGuire Nuclear Station W. L. Cox, Ill, Section Chief North Carolina Department of Health and Human Services Radiation Protection Section 1645 Mail Service Center Raleigh, NC 27699-1645
Abstract
While Unit 1 was in a refueling outage on March 22, 2016, a manual ultrasonic (UT) examination determined that a circumferential indication on Chemical and Volume Control System (NV) Charging piping was rejectable under American Society of Mechanical Engineers (ASME)Section XI Code. Because the indication was classified as rejectable, this event is reportable as a degraded condition in accordance with 10CFR50.73(a)(2)(ii)(A). A stress analysis showed that the identified flaw would not have prevented the associated piping from performing its safety function, so this event did not impact public health and safety.
This circumferential indication was identified during the previous U1 refueling outage, and at that time it was determined that the indication was code allowable based on ASME Section XI Table IWB 3514. The planned follow-up examination performed in the recent refueling outage found this indication to have changed such that it was rejectable per ASME Section XI Table IWB 3514.
The affected NV piping on Unit 1 was replaced during the refueling outage. This LER will be supplemented upon finalization of the cause analysis.
BACKGROUND:
- 6. LER NUMBER I
SEQUENTIAL I REVISION NUMBER NUMBER 01 00
- 3. PAGE 2
OF Applicable Energy Industry Identification [EllS] system and component codes are enclosed within brackets.
McGuire-.specific system and component identifiers are contained within parentheses.
Chemical and Volume Control System [CB] (NV):
The NV system is designed to maintain required water inventory in the Reactor Coolant [AB] (NC) system; maintain seal-water injection flow to the reactor coolant pumps; control water chemistry conditions; and provide emergency core cooling (part of the system shares piping with the Safety Injection [BQ] (NI) system).
The 1 NC1 F-1374 rejectable indication was reported per 10 CFR 50.72 (b)(3)(ii)(A), "Any event or condition that results in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded." An Emergency Notification System report was made to the Nuclear Regulatory Commission (NRC) on March 22, 2016, at 2333 hours0.027 days <br />0.648 hours <br />0.00386 weeks <br />8.877065e-4 months <br />. A 10 CFR 50. 73 (a)(2)(ii)(A) licensee event report is also required due to this degraded condition.
The 1 NC1F-1374 piping indication is located on the 3 inch nominal diameter NV line near where it is connected to the 27.5 inch inside diameter 1A NC cold leg piping.
The 1 NC1F-1374 piping indication addressed by this LER was originally detected during the previous Unit 1 refueling outage. When originally identified, the 1 NC1 F-1374 piping indication was code allowable based on ASME Section XI Table IWB 3514.
This weld was not originally scoped into the MRP-146, "Thermal Fatigue in Normally Stagnant Non-lsolable Reactor Coolant System Branch Lines," program due to piping orientation. It was identified to be included in extent of condition examinations based qn similarities in application to a previously identified MRP-146 flaw on Unit 2 piping. The Unit 2 condition is documented in LER 370/2014-01, Revision 1, and all extent of condition examinations have been completed.
No significant structures, systems, or components were out of service at the time of discovery such that they contributed to the event.
4
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017
EVENT DESCRIPTION
- 6. LER NUMBER I
SEQUENTIAL I REVISION NUMBER NUMBER 01 00
- 3. PAGE 3
OF On March 22, 201.6, while Unit 1 was in a refueling outage (Mode 5), a manual ultrasonic (UT) examination of the [CB] NV branch line connected to the [AB] NC system cold leg piping confirmed a previously identified circumferential indication for 1 NC1F-1374.
The circumferential indication was previously identified and evaluated as acceptable under ASME Section XI code requirements.
The UT techniques used on March 22, 2016, determined that this circumferential indication on the 3 inch nominal diameter NV line connected to the 1A NC cold leg was now rejectable under American Society of Mechanical Engineers (ASME)Section XI rules.
The relevant sequence of events pertaining to the piping flaws is as follows:
09/28/2014 A circumferential indication identified at 1 NC1 F-1374 during MRP extent of condition UT examination. Evaluated acceptable per ASME Section XI code requirements 03/22/2016 Subsequent examination of 1NC1F-1374 during most recent refueling outag~ determined that the circumferential indication was now rejectable per ASME Section XI code requirements 04/04/2016 The affected piping associated with 1 NC1F-1374 was replaced CAUSAL FACTORS:
4 A cause evaluation is currently in progress. The cause evaluation will include a metallurgy lab report detailing an analysis of the flaw. The results of the analysis will be used to further characterize the flaw and provide the cause in a supplement to this LER.
CORRECTIVE ACTIONS
Immediate:
APPROVED BY OMB: NO. 3150-0 I 04 EXPIRES: 01/31/2017
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
YEAR 2016
- 6. LER NUMBER I
SEQUENTIAL I REVISION NUMBER NUMBER 01 00
- 3. PAGE 4
OF 4
The affected 1A [CB] NV piping associated with the circumferential indication was replaced.
Planned:
Complete the cause evaluation.
SAFETY ANALYSIS
The NV piping indication found on Unit 1 had no impact on public health and safety. A stress analysis concluded that despite the presence of the piping flaw, the 3 inch nominal diameter NV piping nozzle would not catastrophically fail when exposed to design basis loadings. The analysis further concluded that the piping would not leak under design basis loadings prior to replacement.
ADDITIONAL INFORMATION
A cause evaluation is currently in progress and the results will be used to identify similar events and if this is a recurring event in a supplement to this LER.
_j