ML16148B057
| ML16148B057 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 09/23/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML16148B056 | List: |
| References | |
| NUDOCS 9110020293 | |
| Download: ML16148B057 (4) | |
Text
o0 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION REPORT BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR RELIEF FROM ASME SECTION XI REQUIREMENTS DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNIT 1 DOCKET NO. 50-269 I. BACKGROUND INFORMATION The Technical Specifications for the Oconee Nuclear Station, Unit 1, states that inservice examination of ASME Code Class 1, 2, and 3 components shall be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code and applicable Addenda as required by 10 CFR 50.55a(g)(4), to the extent practical-within the limitations of design, geometry, and materials of construction, except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).
Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an examination requirement of Section XI of the ASME Code is not practical for his facility, information shall be submitted to the Commission in support of that determination and a request made for relief from the ASME Code requirement. After evaluation of the determination, pursuant to 10 CFR 50.55a(g)(6)(i), the Commission may grant relief and may impose alternative requirements that are determined to be authorized by law, and will not endanger life or property or the common defense and security, and are otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed.
By letter dated September 11, 1991, Duke Power Company (licensee) requested relief from the hydrostatic pressure test requirements of the 1980 Edition though Winter 1980 Addenda of Section XI for a weld made in the pressurizer relief valve discharge line at Oconee Unit 1. The information provided by the licensee in support of the request is evaluated herein to determine if the necessary findings can be made to grant the relief requested.
II. LICENSEE'S REQUEST AND SUPPORTING INFORMATION
- 1. Component for which relief is requested:
(a) Name and Number: Weld Number 1-57-1-56 located on a pipe fitting between a Pressurizer Relief Valve and the Quench Tank.
(b) Function: This piping is between a Pressurizer Relief Valve and the Quench Tank.
9110020293 910923 PDR ADOCK 05000269 P
-2 (c) ISI Class/Duke Class:
ISI Class C (ASME Class 3)
Duke Class C
(d) IWV-2000 Valve Category: N/A
- 2. Reference Code Requirement that has been determined to be impractical:
IWA-4400(a)
"After repairs by welding on the system pressure retaining boundary, a system hydrostatic test shall be performed."
- 3. Licensee's Basis for requesting relief:
Weld 1-57-1-56 is a 4" full penetration butt weld at the 4" side of the pipe/reducer connection located down stream from the Pressurizer Relief Valve 1RC-66. Hydrostatic testing would require inserting blind flanges to isolate the section of pipe containing the new weld.
One of those flanges is inaccessible in that access would require cutting out a welded structural steel hanger. The removal and reinstallation would not be as ALARA efficient as the proposed alternative examination.
Further, a hydrostatic test would generate an excessive amount (approximately 500 gallons) of potentially contaminated water.
- 4. Licensee's Proposed Alternative Examination:
Perform a 100% radio graphic test which would detect welding defects more reliably than a hydrostatic test. In addition, this line will be visually inspected during the Reactor Coolant System pressure test.
- 5. Licensee's reasons why proposed alternative testing is acceptable with respect to the level of quality and safety as well as public health and safety:
The volumetric examination assures an acceptable weld.
Also, this piping is totally contained within the Reactor Building; thus, any leakage would be contained by the Reactor Building.
The combination of the volumetric examination and the reactor building containment system provides an acceptable level of confidence that the health and safety of plant personnel and the general public will not be endangered.
III. STAFF EVALUATION Section XI of the ASME Code requires a hydrostatic test to be performed after a welded repair is made to ASME Code Class 1, 2, and 3 components or piping. The staff has reviewed the licensee's request for relief from this requirement for weld number 1-57-1-56, a Class 3 pipe-to-reducer weld in the discharge line of Pressurizer Relief Valve 1RC-66, and the supporting information for the determination that the requirement is impractical to perform at Oconee Unit 1.
-3 In order to comply with the hydrostatic test requirements, the licensee would have to isolate the piping containing the weld from the pressurizer and quench tank. To accomplish this, blind flanges would have to be inserted between existing flanges, requiring movement of the subject piping. This movement is restricted by a welded structural steel hanger that would require removal and reinstallation.
The licensee has proposed, in lieu of the hydrostatic test, 100%
radiography and visual inspection of the weld. Radiography is a volumetric examination method that is not required by the ASME Code to be performed on Class 3 piping welds but has been proposed by the licensee to demonstrate the weld's structural integrity and its freedom from unacceptable flaws. In addition, the licensee has proposed visual inspection of the weld during the reactor coolant system pressure test.
The NRC staff has determined that the Code requirement to hydrostatically test weld number 1-57-1-56 at Oconee Unit 1 is impractical to perform considering the burden placed on the licensee and the gain in plant safety if the requirement is imposed. The staff finds the alternative tests proposed by the licensee acceptable and in certain aspects more meaningful than the hydrostatic test. In addition, any leakage from failure of the weld, if it occurred, would be confined to the reactor containment and would have an insignificant (if any) adverse impact on the health and safety of the public, plant operation, or personnel.
IV. CONCLUSION The NRC staff concludes, from its evaluation of the determinations made by the Duke Power Company, that certain Section XI ASME Code, 1980 Edition, Winter 1980 Addenda, examination requirements were impractical to perform at the Oconee Nuclear Station, Unit 1. The licensee requested relief from performing the impractical Section-XI ASME Code examination requirements.
Pursuant to 10 CFR 50.55a(g)(6)(i), relief is granted as requested. In granting this request, the staff has determined that the proposed alternative provides an acceptable level of quality and safety and that compliance with the code will result in a hardship without a compensatory increase in the level of quality and safety. In addition, the alternative examination procedures discussed in the body of this report are imposed in lieu of the Code requirements to ensure the structural integrity of the subject components. Granting this relief is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest given due consideration to the burden that could result if the requirements were imposed on the facility.
Principal Contributors: G. Johnson, EMCB L. Wiens, PDII-3 Date:
September 23, 1991
Distribution Docket File, NRC and Local PDRs PDII-3 R/F Oconee R/F T. Murley/F. Miraglia J. Partlow C. Rossi S. Varga G. Lainas L. Berry L. Wiens OGC E. Jordan G. Hill (3 cys for each docket #)
ACRS (10)
GPA/PA OC/LFMB J. Wechselberger, 17G21 L. Reyes, RH