ML20079K600
| ML20079K600 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 12/23/1982 |
| From: | Mark Miller, Stahle C Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20079K602 | List: |
| References | |
| NUDOCS 8301100012 | |
| Download: ML20079K600 (4) | |
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SAFETY EVALUATION REPORT / REQUEST FOR RELIEF FROM REOUIREMENT
.0F HYDROSTATIC TESTING AFTER WELDING SEQUOYAll NUCLEAR PLANT, UNITS 1 & 2 (Docket Nos.60-327 & 50-328)
BACKGROUND By letter dated October 13, 1982, the Tennessee Valley Authority (TVA) informed the NRC of its plans to replace portions of the carbon steel piping in the Essential Raw Coolir.g Water (ERCW) System in Sequoyah Units 1 and 2.
The carbon steel piping will be replaced with stainless steel to reduce corrosion buildup in the systems. TVA is required to perform the piping replacement to the rules of the 1977 Edition through Summer 1978 Addenda of Section XI of the ASME Code.
Section XI requires a hydrostatic test of piping to be performed after welding.
TVA has deternined that a hydrostatic test of the portions of piping replaced is impractical to perform until the scheduled ten-year system hydrostatic test.
and has requested relief from the requirement.
Through conference calls on November 8 and Hovember 15, 1982, the planned replacements and requests were discussed with TVA staff members. The discus-sions resulted in revisions to the original requests, and these revisions were subsequently transmitted by letters of Noveder 18 and December 3,1982. An additional planned replacement of a small section of two-inch discharge piping from a relief valve was transmitted along with a request for' relief from the hydrostatic test for this piping.
REQUEST FOR RELIEF Relief from hydrostatically testing portions of the Essential Raw Cooling Water (ERCW) Systens Piping after welding is requested.
PIPING FOR WilICH RELIEF IS REQUESTED 1.
The supply piping for the auxiliary control air compressor 2B from the 6-inch supply header 2B to and including the 2-inch to 1-inch reducer and to and including valve 2-67-680.
2.
The discharge piping for'the auxiliary control air compressor 2B from and including valve 2-67-683 to and including the 2-inch to 1-inch reducer to the 4-inch to 6-inch reducer.
3.
The supply piping for the auxiliary control air compressor 1A from the 3-inch supply. piping (header 1A) to and including valve 1-67-680.
4.
The discharge piping from the auxiliary control air compressor 1A fron and including valve' 1-67-683 to the 3-inch discharge piping.
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The two-inch discharge piping associated with safety relief valve 0-67-5508 in the EP.CW system.
Class -
TVA Safety Class C ANSI B31.7; C1.3.
Inspection Pequirement Subarticles IWD-7200, IWA-4600, IWA-4400, and Paragraphs IWA-5214 and IWD-5223 of ASME Section XI,1977 Edition, Summer 1978 Addenda, require that replacement piping greater than 1 inch n.p.s. which is installed by welding be hydrostatically pres-j-
sure tested before resumption of service at 1.10 times the system pressure, P,,,
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for systems with design temperature of 200 F or less.
TVA Basis for Relief The replacement of carbon steel piping with stainless steel piping will improve the ERCW system and reduce the possibility of flow reducing corrosion buildup. TVA proposes to defer the system hydrostatic pressure test until after the completion of a number of the replacements. A system hydrostatic pressure test will be per-formed on the then completed replacements by the end of the unit I cycle 3 outage.
The design Code of Record for the piping in question is ANSI B31.7,1969 Edition through S'70 Addenda. This code references ANSI B31.1 for. Class 3 piping fabrica-F tion and installation requirements. Therefore, the fabrication and installation Code of Record for the subject piping is ANSI B31.1,1967 Edition through S'70 Addenda. TVA proposes to install the replacements in accordance with the 1977 Edition of ANSI B31.1, which is permissible under IWA-7110(C) of ASME Section XI, 1977 Edition through S'78 Addenda. The 1977 Edition of ANSI B31.1 requires that the installation welds in question be visually examined, and permits an initial service leak test at nominal operating pressure when a hydrostatic pressure test _
is not practical. However, TVA will perform a liquid penetrant examination of'the installation welds as well as performing an initial service leak test at nominal operating pressure. Because TVA will perforal a more stringent HDE than that required by the installation code, the integrity of the replacement welds is equal to or better than that required by-the installation code.
4 The difference in pressure between a system hydrostatic pressure test (176 psig) and the system functional test (approximately 115 psig) is not significant when 0
the design temperature (less than 200 F) and the strength of this schedule 40 piping are considered.
TVA is presently in the process of replacing all 4-inch and smaller carbon steel piping and associated valves in the ERCW system with stainless steel piping.
Section XI requires TVA to perform systemtydrostatic pressure tests following each replacement. The pressure isolation boundary of each of these system hydro-static pressure tests is identical.
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Requiring redundant system hydrostatic' pressure tests over the same piping and -
valves is. highly impractical when, each time only a small percentage of-piping
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is the replacement.
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Proposed Alternate Inspection i
A system functional test will be performe'd after each replacement'at normal oper-ating pressure of approximately 115 psig and in accordance with IWD-5222. A weld 3
inspection (liquid penetrant inspection) wil1 ~ be performed at each weld. A hydro-2
- static pressm test will be performed by the end of the unit 1 cycle 3 refueling t
outage -(currently scheduled for August 1985 through January 1986).
STAFF EVALUATION l
. Replacing the small-(one-to two-inch diameter) portions of-carbon steel piping with stainless steel will prevent possible' blockage of cooling water in the. Essential Raw 4
l Cooling Water System. In order to comply fully with the Code requirements.for non-destructive testing of piping after welding, the. licensee would have to subject long runs of larger diameter piping to the hydrostatic pressure.because of the inability to isnlate the relatively small sections of replacement piping. The licensee has comitted to perform a system functional test at 115 psig versus 176 psig required by Code 'and to perform a liquid penetrant examination on each weld.' The Code-required hydrostatic test will. be performed by the end of the Unit 1 Cycle 3 i
refueling outage which is currently scheduled to be completed by January 1986 ' con-4 current with completion of piping replacements.
The staff has determined that the Code-required hydrostatic test is impractical considering the licensee's proposed alternate test and weld examinations versus the gain in safety if the requirement were imposed. The system functional test at -
115 psig and the liquid penetrant examination of each weld will provide a high degree of certainty of structural integrity of the replacement piping. Based on
. these facts, the staff concludes that relief from the Code hydrostatic test require-ment may be granted untti January 1986.
j ENVIRONMENTAL CONSIDERATION We have determined that the granting relief does not authorize a change in effluent types-or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further '
L concluded that the relief involves an action which is_ insignificant from the stand-
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point of environmental impact and, pursuant to 10 CFR 551.5(d)(4), that an environ-mental impact statement or negative declaration and environmental. impact appraisal-need not be' prepared in connection with the. issuance of this relief.
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w CONCLUSION We have concluded, based on the considerations discussed above, that:.(1) because granting the relief does not involve a significant increase in the probability or consequences of accidents previously considered, does not create the possibility of an accident of a type different from any evaluated previously, and does not involve a.significant decrease in a safety nargin, the relief does not involve a signif-icant hazards consideration. (2) there is reasonable assurance.that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Comission's regu-1ations and the issuance of this relief will not be inimical to the comon defense and security or to the health and safety of the public.
Dated: December 23, 1982 Principal Contributor: Melanie Hiller, Licensing Branch No. 4, DOL Carl Stahle, Licensing Branch No. 4, DOL nex,_Eower_Systenis_BranchrDSI
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