ML17311A718
| ML17311A718 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/16/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17311A717 | List: |
| References | |
| TAC-M91500, TAC-M91501, TAC-M91502, NUDOCS 9503220233 | |
| Download: ML17311A718 (6) | |
Text
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t UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON> D.C. 2055&0001 ENCLOSURE 1
SAFETY VALUATION BY HE OFFICE 0 NUC EAR EACTOR R GULA 0
RE VEST FOR AUTHORIZA IO 0 US SUBARTIC E IWA-500 OF HE 99 D
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LO VERDE NUCLEAR GENERATING T
IO UNI S 1
2 AND DOCKET NOS.
STN 50-528 ST 50-529 AND STN 50-530
1.0 INTRODUCTION
The Technical Specifications -(TS) for Palo Verde Nuclear Generating Station (PVNGS), Units 1, 2, and 3, state that the inservice inspection and testing of the American Society of Mechanical Engineers (ASHE) Code Class 1, 2, and 3
components shall be performed in accordance with Section XI of the ASHE Boiler and Pressure Vessel Code and applicable Addenda as required by 10 CFR 50.55a(g),
except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).
Section 50.55a(a)(3) of Title 10 of the Code of Federal Regulations states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety.
By letter dated October 21,
- 1987, (E.A. Licitra, Senior Project Manager, Project Directorate V, USNRC, to E.E.
Van Brunt, Jr.,
Executive Vice President, Arizona Nuclear Power Project),
the NRC staff approved the use of a single ASME Code Edition, and specified Addenda, for all three units at PVNGS.
This represents a relief from the requirements of 10 CFR 50.55a(g)(4)(i),
which requires that "inservice examinations of components and system pressure tests conducted during the initial 12-month inspection interval must comply with the requirements in the latest edition and addenda of the Code incorporated by reference in paragraph (b) of this section on the date 12 months prior to the date of issuance of the operating license, subject to the limitations and modifications listed in paragraph (b) of this section."
The NRC staff approved this request for relief with the condition that Arizona Public Service Company (APS or the licensee) establish a common start date for the initial inspection interval for all three units based upon the average date of commercial service in accordance with ASHE Section XI Paragraph IWA-2400(b).
The common start date for the initial inspection interval for PVNGS is March 1987.
The ASHE Code of record approved for PVNGS in the referenced letter was the 1980 Edition through the Winter of 1981 Addenda.
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By letter dated February 3, 1995, the licensee requested approval to utilize the 1992 Edition of the ASHE Code, Subarticle IWA-4500, "Alternate Repair Welding Methods" for the purposes of performing temper bead repair of P3 material.
2.0 f VALUA~O lternative Use of the 1992 Edition of the ASME Code Subarticle IWA-4500 Com onent Identificatio ASHE Class 1 Steam Generator Instrument Nozzles.
SME Code Section XI Re uirements The 1980 Edition through Winter 1981 Addenda,Section XI, IWA-4500 requirements for temper bead welding are contained in Subarticle IWB-4300.
Paragraph IWB-4322. 1(b) requires that the test assembly thickness shall be at least five times the depth of the repair.
In addition, it requires the depth of the cavity to be at least 1-inch.
Therefore, the 1980 Edition through Winter of 1981 Addenda of the ASME Boiler and Pressure Vessel Code requires a
minimum of 5-inch thick material to be used for the qualification of the welding procedure.
The 1992 Edition of the ASHE Code, Subarticle IWA-4500,requires the test assembly thickness to be a minimum of twice the depth of the cavity in the test assembly.
Additionally, this Edition requires the depth of the cavity to be at least one-half the depth of the actual repair, but not less than 1 inch.
Licensee's Basis for Re uest Section 50.55a(a)3 of Title 10 of the Code of Federal Regulations states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed alternatives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The licensee considers the welding repair requirements identified in Subarticle IWA-4500 of the 1992 Edition of the ASHE Code to constitute a
reasonable, safe alternative to the existing welding repair requirements contained in the 1980 Edition, Winter 1981 Addenda, of the ASME Code.
The licensee additionally contends that the 5-inch thick P3 material, required by the PVNGS ASME Code of record, is not readily available and would result in substantial material costs.
The use of external contractors to perform this weld has been pursued by the licensee and is estimated to cost in excess of
$200,000.
The use of the material thickness allowed by the 1992 Edition of the ASME Code, for the purposes of qualifying the welding procedure, would allow PVNGS to utilize readily available material with minimal reliance on costly external contractors.
Requiring the use of the 5-inch thick P3 material would result in a substantial hardship to the plant without a compensating increase in the level of safety or quality.
Therefore, since compliance with the specified requirements of the 1980 Edition, Winter 1981 Addenda, of the ASHE Code would result in hardship or unusual difficulty without a compensating increase in the level of quality and
- safety, the use of the 1992 Edition of the ASHE Code Subarticle IWA-4500 is justified.
3.0
~CONCLUS 0 The staff has reviewed the licensee's request to use an alternative pursuant to 10 CFR 50.55a(a)(3)(ii),
since the requirements of Section XI would result in hardship or unusual difficultywithout a compensating increase in the level of quality or safety.
The staff agrees with the licensee that the use of the provisions of the 1992 Edition of the ASHE Code, Subarticle IWA-4500 requiring a minimum 2-inch thick material for welding procedure qualification constitutes a reasonable, safe alternative to the existing repair requirements contained in the 1980 Edition, Minter 1981 Addenda, of the ASHE Code, Subarticle IWB-4300, Paragraph IWB-4322.1(b), which requires a 5-inch thick test assembly for welding procedure qualification.
Therefore, pursuant to 10 CFR 50.55a(a)(3)(ii),
use of the licensee's proposed alternative for qualification of the welding repair procedure for the steam generator instrument nozzles at PVNGS is authorized as requested.
Principal Contributor:
C. Czajkowski Date:
March 16, 1995