ML18096B252
| ML18096B252 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 02/02/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18096B251 | List: |
| References | |
| NUDOCS 9302110512 | |
| Download: ML18096B252 (4) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE INSERVICE INSPECTION PROGRAMS LICENSE NOS. DPR-70 AND DPR-75 PUBLIC SERVICE ELECTRIC & GAS COMPANY PHILADELPHIA ELECTRIC COMPANY DELMARVA POWER AND LIGHT COMPANY ATLANTIC CITY ELECTRIC COMPANY SALEM NUCLEAR GENERATING STATION. UNITS 1 AND 2 DOCKET NOS. 50-272 AND 50-311
1.0 INTRODUCTION
In a letter dated April 24, 1992, the Public Service Electric & Gas Company (PSE&G) made two requests; to allow use of ASME Code Case N-389 and to allow use of a later edition of ASME Section XI.
The following is clarifying information; our evaluation of these requests is provided in Section 2.0.
The Technical Specification for the Salem Generating Station, Units 1 and 2, states that Inservice Inspection and Testing of American Society of Mechanical Engineers (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), except where specific written relief has been granted by the Commission pursuant to 10 CFR S0.5Sa(g)(6)(i). Paragraph 10 CFR 50.55a(a)(3) 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.
Paragraph 10 CFR 50.55a(g)(4)(iv) permits a licensee to meet the requirements set forth in subsequent editions of ASME Section XI referenced in 10 CFR 50.SSa(b) subject to the limitations and modifications listed therein and subject to Commission approval.
Portions of editions or addenda may be used provided that all related requirements of the respective editions or addenda are met.
Regulatory Guide (RG} 1.147 lists the ASME Code Cases that are acceptable to the NRC staff for implementation in the inservice inspection (ISi) program.
The NRC considers the use of Code Cases to be optional for the user and not a mandatory requirement.
1,.----9302110512 930202
. PDR ADOCK 05000272 P
PDR 2.0 EVALUATION 2.1 Request for Approval Related To Use of Code Case N-389 For Salem, Unit 1 2.1.1 Code Requirements The code requirements for Repair Procedures and Replacements are defined in IWA-4000 and IWA-7000, respectively.
2.1.2 Licensee's Request In a letter dated April 24, 1992, the licensee requested approval to use Code Case*N-389 and to adopt the 1986 Edition of ASME Section XI for repairs, replacement, and modifications.
2.1.3 Licensee's Basis for Request Regulatory Guide 1.147, Revision 9, states that "Code Case N-389 is acceptable subject to the following condition in addition to those conditions specified in the Code Case:
The applicant should submit for approval the appropriate edition and addenda of the Code that is to be used for the repair, replacement, or modification before start rif the work."
The 1986 Edition of ASME Section XI is referenced in 10 CFR 50.55a(b).
2.1.4 Staff Evaluation Code Case N-389 was approved by the ASME Council on July 25, 1983, and re-affirmed twice for use on May 14, 1986, and May 14, 1989~ The reason for the condition in RG 1.147 is that the plant owner may want to use rules for repairs and replacements contained in published editions of ASME Section XI that have not yet been referenced in the regulations.
In the subject case for Salem Unit 1, the licensee proposes to use the 1986 Edition that is referenced in 10 CFR 50.55a(b).
As part of the regulatory review process, IWA-4000 and IWA-7000 of the 1986 Edition of Section XI have been determined to provide an acceptable level of quality and safety. Therefore, the licensee's proposal is acceptable pursuant to 10 CFR 50.55a(a)(3)(i).
2.2 Request Number 2 Related to the Substitution of Paragraph IWA-5250(a)(2) from Addenda Through 1990 for Both Units 2.2.1 Code Requirement:
Paragraph IWA-5250(a)(2) of the 1986 Edition requires that if leakage occurs at a bolted connection, the bolting shall be removed, VT-3 visually examined for corrosion, and evaluated in accordance with IWA-3100.
2.2.2 Licensee's Request The licensee requests approval to substitute the referenced paragraph from the 1989.Edition including Addenda through 1990 as an alternative in lieu of the wording in the 1986 Edition.
2.2.3 Licensee's Basis for Relief The proposed alternative requirement is included in a published revision of ASME Section XI as corrective measure for leakage at a bolted connection.
In the 1990 Addenda, the referenced paragraph states, "If leakage occurs at a bolted connection one of the bolts shall be removed, VT-3 examined, and evaluated in accordance with IWA-3100.
The bolt selected shall be the one closest to the source of leakage.
When the removed bolt has evidence of degradation, all remaining bolting in the connection shall be removed, VT-3 examined and evaluated in accordance with IWA-3100.
11 2.2.4 Staff Evaluation The 1989 Edition of ASME Section XI, including Addenda through 1989, has been referenced in 10 CFR 50.55a(b). The requirements of paragraph IWA-5250(a)(2) are the same for the 1986 Edition and the 1989 Addenda.
The licensee's proposed alternative was first published in the 1990 Addenda and is also included in the 1992 Edition of ASME Section XI.
The objective of the original and revised code requirement is to detect degradation of the fastener that has resulted in leakage of the joint.
The Code is not attempting to address component alignment or gasket problems associated with a leaking flanged connection.
Of course, degradation of the bolted connection may be a direct result of attempts to resolve misalignment problems.
The examination method is VT-3, which is conducted to determine the general mechanical and structural condition of components and their supports by verifying parameters such as clearances, settings, and physical displacements; and to detect discontinuities and imperfections, such as loss of integrity at bolted or welded connections, loose or missing parts, debris, corrosion, wear, or erosion.
The ASME Council decided in the 1990 Addenda to accept a sample of bolts, with a provision for sample expansion, instead of a visual examination of all bolts after the detection of leakage.
The current revision of the Code was published after due consideration of the acceptance standards for the number of degraded bolts that could be present before a significant safety problem would exist.
Based on the information presented above, the NRC staff has concluded that requirements published in paragraph IWA-5250(a)(2) in the 1990 Addenda and the 1992 Edition of ASME Section XI would be capable of detecting a significant safety problem and, therefore, provide an acceptable level of quality and safety pursuant to 10 CFR 50.55a(a)(3)(i). However, the NRC staff's conclusions are based on the following two.assumptions:
(1)
The individual bolts have not been subjected to a preload exceeding the Owner's Design Specifications for the fasteners; and (2)
In the event that the licensee believes that degradation of the fasteners has occurred, the required VT-3 visual examinations will be supplemented by surface and volumetric methods pursuant to other ASME Code requirements, such as, paragraph IWC-3200 "Supplemental Examinations."
3.0 CONCLUSION
S The licensee has made two requests by letter dated April 24, 1992.
The first was a "proforma" request to use Code Case N-389 that designated the 1986 Edition of ASME Section XI.
The licensee's proposed alternative requirements have been referenced in the regulations and, therefore, are determined by the NRC staff to be acceptable pursuant to 10 CFR 50.55a{a}{3}{i}.
The second request was to use paragraph IWA-5250{a}{2} from the 1990 Addenda of ASME Section XI.
The licensee's proposed alternative requirement is a corrective measure that the ASME Council also approved in the 1992 Edition of the Code.
The subject Code requirements contained in the 1986 Edition and the 1990 Addenda address potential inservice degradation at the flanged connections due to normal operation. The fundamental assumption in the original and revised code inspection methods is that the bolts were not overstressed during attempts to correct alignment problems or leakage past the gasket.
In addition, the ASME Council has provided requirements and guidance regarding volumetric and surface methods to supplement the VT-3 visual examination.
Based on the above, the NRC staff concludes that the licensee's proposal to use paragraph IWA 5250(a)(2) from the 1990 Addenda is acceptable pursuant to 10 CFR 50.55a(a}(3)(i}.
Principal Contributor:
M. Hum Date: February 2, 1993