ML17264A446
| ML17264A446 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 04/05/1996 |
| From: | Shankman S NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17264A445 | List: |
| References | |
| NUDOCS 9604120239 | |
| Download: ML17264A446 (8) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, O.C. 20555-0001 V
U Y TH OFF CE OF NUC AR R ACTOR R GULATION T
TO THE INS RVICE NSPECTION PROGRAM THIRD 10-YEAR INT RVAL FOR ROCHESTER GAS AND ELECTRIC CORPORATION R.
E.
GINNA NUCLEAR POWER PLANT DOCKET NO. 50-244 1.N iNTR Dll Tl N
The Technical Specifications for R.
E. Ginna Nuclear Power Plant (Ginna) state that the inservice inspection (ISI) and testing of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASHE Code)
Class 1, 2, and 3 components shall be performed in accordance with Section XI of the ASME Code and applicable Addenda as required by 10 CFR 50.55a(g),
except where
'pecific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6).
Part 10 of 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.
Pursuant to 10 CFR 50.55a(g)(4),
ASHE Code Class 1, 2, and 3 components (including supports) shall meet the requirements that become effective subsequent to editions specified in 10 CFR 50.55a(g)(2) and (g)(3), except the design and access provisions and the preservice examination requirements, set forth in the ASHE Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components,"
to the extent practical within the limitations of
- design, geometry, and materials of construction of the components.
The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and,subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASHE Code incorporated by reference in 10 CFR 50.55a(b) on the date twelve months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.
The applicable edition of Section XI of the ASHE Code for Ginna's third 10-year ISI Interval is the 1986 Edition.
Enclosure 9604120239
'760405 PDR ADOCIl'5000244 P
Pursuant to 10 CFR 50.55a(g)(5)(iii), if the licensee determines that conformance with an examination requirement of Section XI of the ASHE Code is impractical for its facility information should be submitted to the Commission in support of that determination.
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; will not endanger life, 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 letters dated October ll, and November 27,
- 1995, Rochester Gas and Electric Corporation (RG&E) requested approval of Relief Request No.
31 for the implementation of the alternative rules of Section XI, ASHE Code Case N-416-1 dated February 15, 1994, entitled "Alternative Pressure Test Requirement for Welded Repairs or Installation of Replacement Items by Welding Class 1,
2.,
and 3,Section XI, Division 1," pursuant to 10 CFR 50.55a(a)(3) to be applied to the ISI program for Ginna.
The NRC staff has reviewed and evaluated the licensee's request and supporting information to use ASHE Code Case N-416-1 as a proposed alternative to, the Code requirements for Ginna.
2.
EUUAAT N
CODE CASE N-416-1 ALTERNATIVE PRESSURE TEST REQUIREMENT FOR WELDED REPAIRS OR INSTALLATION OF REPLACEMENT ITEMS BY WELDING CLASS 1, 2, and 3 - SECTION 'XI, DIVISION 1 Component Identification ASHE Code Class 1, 2, and 3 Systems ASHE Code Section XI Third Interval Requirements The 1986 Edition,Section XI, IWA-4400(a) requires that a system hydrostatic test be performed in accordance with IWA-5000 after repairs by welding on the pressure retaining boundary.
Licensee's Basis for Request "Industry studies have shown that the hydrostatic pressure test specified in IWD-5223(a) is not a structural integrity test of the weld, but in fact a
leakage test performed at a high pressure.
Using surface examination methods on the weld or volumetric examinations methods on a completed weld provide more comprehensive results in the determination of the integrity of the weld.
In addition, a system inservice or functional test and VT-2 examination shall be performed on the completed welds."
"In addition, the added burden of requiring, special maintenance activities for isolation of components to be tested, such as:
temporary gagging or removal of
relief valves installed to prevent overpressurization, leaktight repair of valving which does not normally serve a pressure isolation function, pinning of applicable support and installation of portable hydrostatic pressure pumps can be avoided.",
Proposed Alternative Examination The licensee proposes to apply Code Case N-416-1 as alternative rules for welded repairs or installation of replacement items by welding in Class 1, 2, and 3 piping.
In addition, the licensee proposes to perform surface examinations on the root pass layer of butt and socket welds on the pressure retaining boundary of Class 3 piping and components.
Evaluation/Conclusions In lieu of hydrostatic pressure testing for welded repairs or installation of replacement items by welding, ASIDE Code Case N-416-1 requires a visual examination (VT-2) be performed in conjunction with a system leakage testing using the 1992 Edition of Section XI, in accordance with Paragraph IWA-5000, at nominal operating pressure and temperature.
This code case also specifies that nondestructive examination (NDE) of the welds be performed in accordance with the applicable Subsection of the 1992 Edition of Section III.
The 1989 Edition of Sections XI and III are the latest editions referenced in 10 CFR 50.55a.
The staff has compared the system pressure test requirements of the 1992 Edition of Section XI to the requirements of IWA-5000 of the 1989 Edition of Section XI.
In summary, the 1992 Edition imposes a more uniform set of system pressure test requirements for Code Class 1, 2, and 3 systems.
The terminology associated with the system pressure test requirements for all three code classes has been clarified and streamlined.
The test frequency and test pressure conditions associated with these tests have not been changed.
The hold time or operation time for system leakage tests has been increased.
Although the corrective actions with respect to removal of bolts from leaking bolted connections has been relaxed in the 1992 Edition, this relaxation has been accepted by the staff in previous safety evaluations.
The post-welded repair NDE requirements of the 1992 Edition of Section III remain the same as the requirements of the 1989 Edition of Section III. Therefore, the staff finds this aspect of Code Case N-416-1 to be acceptable.
Hardships are generally encountered with the performance of hydrostatic testing performed in accordance with the Code.
Hydrostatic pressure testing frequently requires significant effort to set up and perform.
The need to use special equipment, such as temporary attachment of test pumps and gages, and the need for individual valve lineups can cause the testing to be on critical path.
Piping components are designed for a number of loadings that would be postulated to occur under the various modes of plant operation.
Hydrostatic testing only subjects the piping components to a small increase in pressure over the design pressure and, therefore, does not present a significant
challenge to pressure boundary integrity.
As such, hydrostatic pressure testing is primarily regarded as a means to enhance leakage detection during the examination of components under pressure, rather than solely as a measure to determine the structural integrity of the components.
The industry experience has demonstrated that leaks are not being discovered as a result of hydrostatic test pressures propagating a preexisting flaw through wall.
This experience indicates that leaks in most cases are being found when the system is at normal operating pressure.
This is largely due to the fact that hydrostatic pressure testing is required only upon installation and then once every 10-year inspection interval, while system leakage tests at nominal operating pressures are conducted a minimum of once each refueling outage for Class 1 systems and each 40-month inspection period for Class 2 and 3 systems.
Leaks may also be found, during system walkdowns by plant operators as often as once a shift, when the system has been in operation and under normal system pressures for a period of time that is much longer than the hold times required for a hydrostatic test.
This experience demonstrates that a slight higher pressure imposed on the pressure boundary components during a hydrostatic testing may produce only a minor improvement in leak detection capability over a nominally pressurized system.
This minor improvement of leak detection capability does not offset or justify certain hardships created in setting up a hydrostatic test due to a slightly higher test pressures.
Following the completion of welding, the code requires volumetric examination of repairs or replacements in Code Class 1 and 2, but would also allow only a surface examination of the final weld pass in Code Class 3 piping components.
There are no NDE requirements for Code Class 3 components except for visual examination for leaks in conjunction with the 10-year hydrostatic tests and the periodic pressure tests.
Considering the NDE performed on Code Class 1 and 2 systems and considering that the hydrostatic pressure tests rarely result in pressure boundary leaks that would not occur during system leakage tests at slightly lower test pressures, the staff believes that increased assurance of the integrity of Class 1 and 2 welds does not commensurate with the burden of performing hydrostatic testing.
However, considering the nature of NDE requirements for certain Code Class 3 components, the staff does not believe that the requirement in ASHE Code Case N-416-1 of only performing system leakage testing is an acceptable alternative unless additional surface examinations on the root (pass) layer of butt and socket welds are performed on the pressure retaining boundary of Class 3 components when the surface examination method is used in accordance with the 1992 Edition of ASNE Code Section III.
In its October 11, 1995, letter, the licensee proposed and committed to perform this additional examination.
The staff finds this commitment acceptable.
For clarification, it should be noted that, consistent with the Code Case requiring performance of NDE in accordance with the methods and acceptance criteria of the 1992 Edition of Section III, the scope of examination should also be in accordance with the 1992 Edition of Section III.
The additional
surface examination of the root layer of Class 3 pressure retaining welds should be performed only when those pressure retaining welds are required to have a surface examination performed in accordance with the 1992 Edition of Section III. Therefore, the staff finds the licensee's proposal acceptable that for those Class 3 welds receiving radiography, no additional surface examination of the root layer needs to be performed.
- 3. 0
~CO US IO The staff concludes that compliance with the code hydrostatic testing requirements for welded repairs or replacements of Code Class 1, 2, and 3
components would result in hardships without a compensating increase in the level of quality and safety.
Accordingly'the licensee's proposed alternative to use ASME Code Case N-416-1 is authorized for Ginna, pursuant to 10 CFR 50.55a(a)(3)(ii) in conjunction with the proposed additional surface examinations which shall be performed on the root (pass) layer of butt and socket welds on the pressure retaining boundary of Class 3 components when the surface examination method is used in accordance with the 1992 Edition of ASME Code,Section III.
Use of ASME Code Case N-416-1, with the proposed additional surface examination as noted above, is authorized for the duration of the currently approved ISI plan.
Principal Contributor:
John Huang Date:
April 5, 1996
April 5, 1996 R. Mecredy The enclosed SE provides the results of the NRC's review and TAC No. M93839 is considered complete.
Sincerely, ORIGINAL SIGNED BY:
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Docket: No. 50-244 r(
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Enclosure:
Safety Evaluatio'n r
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PUBLIC
" PDI-1 Reading SVarga JZwolinski.,
SShankman AJohnson SLittle GBagchi JHuang GHill (2)
ACRS OGC LDoerf1ein RI/DRP WDean Susan Frant Shankman, Acting Director Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation DOCUMENT NAME:
G: iGINNAtI,G1 93839. REL To receive a copy of this document, indicate In the box: " " ~ Copy without enclosures "E" ~ Copy with enclosures "N" ~ No copy OFFICE NAME DATE LA:PDI-1 SLittl 03/0 /96 PM:PDI-1 0-OG AJohnson:
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