ONS-2015-039, Fifth Ten Year Inservice Inspection Interval, Relief Request No. 14-ON-001; Inspection Impracticality of Letdown Cooler Nozzle Inside Radius Sections
| ML15132A279 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/04/2015 |
| From: | Batson S Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ONS-2015-039 | |
| Download: ML15132A279 (9) | |
Text
4DUKE n ENERGY.
ONS-2015-039 May 4, 2015 Scott L. Batson Vice President Oconee Nuclear Station Duke Energy ONO1VP I 7800 Rochester Hwy Seneca, SC 29672 o: 864.873.3274 f 864.873. 4208 Scott.Batson@duke-energy.com ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 10 CFR 50.55a Duke Energy Carolinas, LLC (Duke Energy)
Oconee Nuclear Station, Units 1, 2 and 3 Docket Numbers 50-269, 50-270, 50-287 Renewed License Numbers DPR-38, DPR-47, and DPR-55
Subject:
Fifth Ten Year Inservice Inspection Interval, Relief Request No. 14-ON-001; Inspection Impracticality of Letdown Cooler Nozzle Inside Radius Sections
References:
- 1. Duke Energy Letter, Oconee, Units 1, 2 and 3 - Fifth Interval Inservice Inspection Plan, dated July 15, 2014, (ADAMS Accession No. ML14202A008)
Pursuant to 10 CFR 50.55a(g)(5)(iii), Duke Energy requests the NRC to grant relief regarding impracticality to inspect inside radius sections of the Letdown Cooler nozzles for the duration of the fifth (ten-year) inservice inspection (ISI) interval. Relief Request 14-ON-001 renews a relief request which was approved for the previous two ISI intervals which describes the impracticality of the examination and provides the justification for granting relief from the edition of Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) applicable to the fifth ISI Interval.
This relief is needed prior to the Oconee Unit 1, 2016 Fall refueling outage (1 EOC29) projected to start November 5, 2016. Duke Energy requests approval by May 1, 2016 in support of planning for 1 EOC29. The relief request details are provided as an enclosure to this letter.
If there are any questions or further information is needed you may contact David Haile at (864) 873-4742, Sincerely, Scott L. Batson Vice President Oconee Nuclear Station Enclosure Relief Request Serial #14-ON-001:
Request for Relief in Accordance with 10 CFR 50.55a(g)(5)(iii) for the Letdown Cooler Nozzle Inside Radius Sections
ONS-2015-039 May 4, 2015 Page 2 cc (with enclosure):
Mr. Victor McCree, Regional Administrator U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 Mr. James R. Hall, Project Manager (ONS)
(by electronic mail only)
U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop O-8B1 Rockville, MD 20852 Jeffery Whited (by electronic mail only)
U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop O-8B1A Rockville, MD 20852 Mr. Eddy Crowe NRC Senior Resident Inspector Oconee Nuclear Station
Enclosure to ONS-2015-039 Duke Energy Carolinas, LLC Oconee Nuclear Station, Units 1, 2, and 3 Relief Request Serial #14-ON-001 Request for Relief in Accordance with 10 CFR 50.55a(g)(5)(iii) for the Letdown Cooler Nozzle Inside Radius Sections Fifth Inservice Inspection Interval
Duke Energy Carolinas, LLC Relief Request Serial No. 14-ON-001 Page 2 of 7
- 1. ASME Code Component(s) Affected High Pressure Injection System, ISI Class 1 Letdown Cooler Nozzle Inside Radius Sections.
Oconee Unit 1 has two Letdown Coolers 1A and 1 B. Each component has typically four B3.160 welds. The coolers also have operational ready spares of similar design that are rotated from spare to installed components as required by maintenance.
Oconee Unit 2 has two Letdown Coolers 2A and 2B. Each component has typically four B3.160 welds. The coolers also have operational ready spares of similar design that are rotated from spare to installed components as required by maintenance.
Oconee Unit 3 has two Letdown Coolers 3A and 3B. Each component has typically four B3.160 welds. The coolers also have operational ready spares of similar design that are rotated from spare to installed components as required by maintenance.
2. Applicable Code Edition and Addenda
ASME Boiler and Pressure Vessel Code,Section XI, 2007 Edition with the 2008 Addenda.
- 3.
Applicable Code Requirement
IWB-2500, Table IWB-2500-1, Examination Category B-D, Full Penetration Welded Nozzles in Vessels, Item No. B3.160, Nozzle Inside Radius Section require a volumetric examination of the of inside radius sections on heat exchanger nozzle to shell welds.
- 4.
Impracticality of Compliance Due to the size and geometry of the nozzle inside radius on the Letdown Coolers, Duke Energy has been unable to perform a meaningful (i.e. unable to get sound into the area of interest) volumetric examination. The weld joint geometry is essentially a branch connection arrangement using a set-on nozzle and the nozzle thickness prevents access to the examination volume. RT examination method has the same restrictions with geometry as UT and therefore is not a practical method to use either.
- 5.
Burden Caused by Compliance In order to scan all of the required volume, the Letdown Cooler nozzles would have to be redesigned to allow scanning of the inner radius, which is impractical. See Attachment A for a drawing (OM-201-3276 and 1 N37804-2) of the typical Letdown Coolers. The drawing in Attachment "A" is for the Unit 2 "B" Letdown Cooler but the configuration for the nozzle inside radius sections is the same for all 3 Units and all letdown coolers of this design.
- 6.
Proposed Alternate Examination None proposed or planned.
Duke Energy Carolinas, LLC Relief Request Serial No. 14-ON-001 Page 3 of 7
- 7.
Duration of Proposed Alternative The proposed alternative is requested for use during the 5th inservice inspection intervals for Oconee Units 1, 2 and 3, beginning July 15, 2014, currently scheduled to end July 15, 2024.
- 8.
Precedents 8.1. Duke Energy, Oconee Nuclear Station Units 1, 2, and 3, Relief Request No. ONS-009 submitted May 12,1994 and approved November 11, 1995, TAC Nos. M88484, M88485, and M88486.
8.2. Duke Energy Corporation, Oconee Nuclear Station Units 1, 2, and 3, Relief Request No. 04-ON-015 submitted December 21, 2004 and approved June 14, 2005 (ML043630370), TAC Nos. M5485, M5486, and M5487.
- 9. Justification for Granting Request for Relief The ultrasonic examination of the weld volume adjacent the inside radius section, as required by ASME Section Xl, Table IWB-2500-1, Examination Category B-D, Item Number B3.150 is a more critical location and will provide adequate assurance of the integrity of the welded connection.
Duke Energy will use code required pressure testing and VT-2 visual examination to ensure component integrity. The Code requires (reference Table IWB-2500-1, Examination Category B-P, All pressure Retaining Components (Item Number B15.10 Heat Exchangers) that a system leakage test be performed after each refueling outage for Class 1 components. These tests require a VT-2 visual examination for evidence of leakage. This testing will provide reasonable assurance of weld/component integrity.
In addition to the above Code required examinations (volumetric and VT-2 visual examination during pressure testing), there are other activities which provide a high level of confidence that, in the unlikely event that leakage did occur through these inside radius sections, it would be detected. Specifically, leakage from these inside radius sections would be detected by monitoring of the Reactor Coolant System (RCS) inventory, which is performed once each shift under unit specific procedure PT/1, 2, or 3/A/0600/10, "RCS Leakage".
This RCS leakage monitoring is a requirement of Technical Specification 3.4.13, "Reactor Coolant System Leakage". Any leakage is also evaluated in accordance with this Technical Specification.
The leakage could also be detected through several other methods. One is the Reactor Building air particulate monitor. This monitor is sensitive to low leak rates; the iodine monitor, gaseous monitor and area monitor are capable of detecting any fission products in the coolant and make these monitors sensitive to coolant leakage. A second is the level indicator in the Reactor Building normal sump. A third is a loss of level in the Letdown Storage Tank.
Based on the required volumetric examinations, VT-2 test, and other activities previously listed, it is Duke's belief that this provides a reasonable assurance of component integrity. Thus, an acceptable level of quality and safety will have been achieved and will not endanger public health and safety.
Duke Energy Carolinas, LLC Relief Request Serial No. 14-ON-001 Page 4 of 7 Attachments to 14-ON-001 Letdown Cooler Drawings For Unit 2 (Typical For Units 1, 2, and 3)
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OM-201-3276 Sheets 1 & 2, Letdown Cooler Assembly 1 N37804-2, Letdown Cooler "2B " Serial Number N37804-2
BILL OF MATERIALS W
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- 2. ALL WELD NO'S SHALL BE PRECEDED BY 1-N37804-2
- 3.
LAST WELD NO. WJ36VI LAST THD JOINT -
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REF.LAYOUT DRAWING OM O
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PSIG TITL DUKE POWER COYAP A NY OCONEE NUCLEAR STATION UNIT LE, LETDOWN COOLER "2B" SERIAL NUMBER N37804-2 2d
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HP LINE NO.
NA 1 THE DRAWIN NUMBER WILL BE THE COOLER SERIAL NUMBER OOE SEC III OVL LAS NAS ALL 8 COOLERS WILL BE DESIGNATED AS UNIT I SYSTEM HP(5tA) i CITIN 1
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- 9.
THIS COOLER IS CURRENTLY LETDOGWN CDOLER 2B' PIIGsPEC.N 0NWO 1997784 ADD WELDS WJ3IV - WJ36V, ADD BOM ITEMS A AND SB CK CRH
- 10.
VENDER WELDS (REF. OM-201. -3276. 00 1) 0 ADD NOTES 7-10 1016/1I 10/24/11 LOCATION REACTOR BUILDING DRAWNBY T
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