ML20086M463
| ML20086M463 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 07/19/1995 |
| From: | Maxfield G WISCONSIN ELECTRIC POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| PBL-95-0173, PBL-95-173, NUDOCS 9507240285 | |
| Download: ML20086M463 (5) | |
Text
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.Electnc POWER COMPANY Point Booch Nuclear Pkrit 6610 Nuclear Rd, Two hers.VA 54241 (414) 755-2321 PBL 95-0173 July 19, 1995 U. S. NUCLEAR REGULATORY COMMISSION Document Control Desk Mail Station P1-137 r
Washington, D. C.
20555 i
Gentlemen:
i DOCKETS 50-266 AND 50-301 ASME SECTION XT PRESSURE TEST PROGRAM REOUESTS FOR RELIEF POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 Enclosed are two requests for relief associated with our Third Interval ASME ion XI Pressure Test Program. We anticipate that implementation of these asts for relief, if approved, will result in significant cost savings as
. 41 as increased availability for safety-related systems. We look forward to receipt of your response for these two requests.
i Should you have any quentions or require any additional information regarding this matter, please do not hesitate to contact us.
Sincerely,
(
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G. J. Maxfi ld Plant Manager DEK/ caw Enclosure j
j cca NRC Resialent Inspector NRC Regional Administrator, Region III John G.
Gault, HSB
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i RELIEF REOUEST PTP-3-05 1
l COMPONENTS:
ASME Class 3 pressure retaining components.
DRAWINGS:
MULTIPLE.
ASME SECTION XI (1986 EDITION) REOUIREMENT:
l 10-Year flydrostatic Tests required by Table IW D-2500-1, Categories D-A, D-3, and D-C.
I IWD-5222 SYSTEM IIYDROSTATIC TEST l
(a)
The system hydrostatic test pressure shall be at least 1.10 times the system pressure P f r systems u
f with Design Temperature of 200*F or less, and at least 1.25 times the system pressure P for systems g
[
with Design Temperature above 200'F. The system pressure P shall be the lowest pressure setting u
f among the number of safety or relief valves provided for overpressure protection within the boundary l
of the system to be tested. For systems (or portions of systems) not provided with safety or relief valves, the system design pressure P shall be substituted for P -
g u
PROPOSED ALTERNATE REOUIREMENT:
In lieu of the 10-year hydrostatic tests required for ASME Class 3 pressure retaining components by Section XI, Division 1, Table IWD-2500-1, Categories D-A, D-B, and D-C, the alternative rules specified in ASME Section XI Code Case N-498-1 (Approved by the ASME on May 11,1994) shall be used.
l BASIS FOR RELIEF:
l Satisfying this provision of the Code requires significant resources to address operational concerns and personnel and plant safety issues related to placing the plant in a non-conventional configuration to support, isolate, and/or obtain the above normal operating pressure required for hydrostatic testing. During hydrostatic testing, the affected system is unavailable to support plant operations, even if called upon to perform its safety function, during the time required to isolate and align the system; perform fill and vent operations; connect an external hydro pump and provide for pressure relief capability for the test volume; maintain pressure for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated systems; install and remove blank flunges and/or spool pieces; remove and reinstall system relief valves; recalibrate instrumentation; and realign the retem for service; etc. Although hydrostatic testing is performed with the utmost of care utilizing detailed procedures and highly trained personnel, there is always a very small possibility of damaging equipment or experiencing j
I some other unforeseen incident which could affect plant safety.
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.. _ _. - _ _ _ __ ____________________________________________________ _ _____o
a l
BASIS FOR RELIEF (CONTINUED):
Information prepared in conjunction with ASME Code Case N-498-1 notes that the system hydrostatic test is not a test of the structural integrity of the system, but rather an enhanced leakage test. That this was the original intent is indicated in the paper by S. H. Bush and R. R. Maccary, Development ofin-Service inspection Safety Philosophyfor U.S.A.
Nuclear Power Plants, ASME,1971. Piping components are designed for the number of loadings that are postulated to occur under the various modes of plant operation. Hydrostatic testing only subjects the piping components to a relatively small increase in pressure over the design pressure, and thus, does not present a significant challenge to pressure boundary integrity. Piping dead weight, thermal expansion, and seismic loads, all of which may present a far greater challenge to the structural integrity of the system than fluid pressure, are not part of the loading imposed during hydrostatic testing. Accordingly, hydrostatic testing is primarily regarded as a means to enhance leakage detection during the examination of components uader pressure, rather than as a measure of the structural integrity of the components.
The alternate pressure tests permitted by ASME Code Case N-498-1 fulfill the same purpose as a hydrostatic pressure test (i.e., a check for component leakage) at a reduced cost. Additionally, plant safety is increased when the alternative rules are utilized over hydrostatic testing in that the ability of the affected system to be able to perform its safety function is not challenged as it is during the hydrostatic testing process Considering the negligible amount of increased assurance provided by the elevated pressure associated with a hydrostatic test in comparison to the pressure seen during i
a system leakage test, versus the hardship associated with the ASME Section XI 10-year hydrostatic testing requirements, compliance with the Section XI 10-year hydrostatic testing requirements results in hardship and/or unusual difficulty without a compensating increase in the level of quality and safety. Accordingly, relief may be granted under 10 CFR 50.55a(a)(3)(ii).
It should be noted that the alternative rules specified in ASME Code Case N-498-1 for ASME Class 1 and 2 systems are effectively already available for use. These alternative rules are equivalent to those called out under ASME Code Case N-498 (approved by the ASME on May 13,1991), which is listed in NRC Regulatory Guide (RG) 1.147 as being available to all licensees. As a result, this request for relief (PTP-3-05) is written to apply only to ASME Class 3 systems.
STATUS:
Awaiting NRC Response, j
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4 RELIEF REOUEST PTP-3-06 i
COMPONENTS:
ASME Class 1,2, and 3 pressure retaining components.
ERAWINGS:
MULTIPLE.
ASME SECTION XI (1986 EDITION) REOUIREMENT:
IWA 5214 REPAIRS AND REPLACEMENTS (a)
A component repair or replacement shall be pressure tested prior to resumption of service if required by IWA-4400 and IWA-4600.
(b)
'Ihe test pressure and temperature for a system hydrostatic test subsequent to the component repair or replacement shall comply with the system test pressure and temperature specified in IWB-5222, IWC-5222, and IWD-5223, as applicable to the system which contains the repaired of replaced component.
PROPOSED ALTERNATE REOUIREMENT:
(a)
In lieu of the hydrostatic test required following repair or replacement of an ASME Class 1,2, or 3 component by welding, the alternative rules specified in ASME Code Case N 416-1 (approved by the ASME on February 15,1994) may be used.
(b)
In addition to the alternative rules specified in ASME Code Case N-416-1, for ASME Class 3 components additional NDE will also be performed. The additional NDE will consist of either a surface examination or volumetric exammation of the final weld of the root (pass) layer of socket and butt welds on the pressure retaining boundary of ASME Class 3 components.
BASIS FOR RELIEF:
Satisfying this provision of the Code requires significant resources to address operational concerns and personnel and plant safety issues related to placing the plant in a non-conventional configuration to support, isolate, and/or obtain the above normal operating pressure required for hydrostatic testing. During hydrostatic testing, the affected system is unavailable to support plant operations, even if called upon to perform its safety function, during the time required to isolate and align the system; perform fill and vent operations; connect an external hydro pump and provide for pressure relief capability for the test volume; maintain pressure for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated systems; install and remove blank flanges and/or spool pieces; remove and reinstall system relief valvts; recalibrate instrumentation; and realign the system for service; etc. Although hydrostatic testing is performed with the utmost of care utilizing detailed procedures and highly trained personnel, there is always a very small possibility of damaging equipment or experiencing some other unforeseen incident which could affect plant safety.
Page 1 of 2
..< s BASIS FOR RELIEF (CONTINUEDh Piping components are designed for the number of loadings that are postulated to occur under the various modes of plant operation. Ilydrostatic testing only subjects the piping components to a relatively small increase in pressure over the design pressure, and thus, does not present a significant challenge to pressure boundary integrity. Piping dead weight, thermal expansion, and seismic loads, all of which may present a far greater challenge to the structural integrity of the system than fluid pressure, are not part of the loading imposed during hydrostatic testing. Accordingly, hydrostatic testing is primarily regarded as a means to enhance leakage detection during the examination of components under pressure, rather than as a measure of the structural integrity of the components.
Nuclear industry experience indicates that leaks are not being discovered as a result of hydrostatic test pressures propagating a preexisting flaw through wall. Rather, leaks in most cases are detected with the system at normal operating pressure. To a large extent, this is due to the fact that hydrostatic testing is required relatively infrequently in comparison to routine inspections conducted at normal operating pressures. Considering the NDE performed on ASME Class I and 2 systems and that the relatively infrequent hydrostatic testing rarely, if ever, detects leakage which could not have been found by a pressure test at normal operating pressure, the increased assurance provided by the elevated pressure associated with a hydrostatic test results in hardship and/or unusual difficulty without a compensating increase in the level of quality and safety. Accordingly, relief may be granted under 10 CFR 50.55a(a)(3)(ii).
With respect to ASME Class 3 components, it is acknowledged that some additional compensatory measures are needed due to the nature of the NDE requirements, or lack thereof, for ASME Class 3 components. However, when the additional NDE requirements for ASME Class 3 components, as discussed in the Proposed Alternate Requirement section above, are taken into consideration, the increased assurance provided by the elevated pressure associated with a hydrostatic test on ASME Class 3 components results in hardship and/or unusual difficulty without a compensating increase in the level of quality and safety. Again as before, relief may be granted under 10 CFR 50.55a(a)(3)(ii).
STATUS:
Awaiting NRC Response.
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