ML20140D686
| ML20140D686 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 04/11/1997 |
| From: | Wozniak D COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BYRON-97-5081, NUDOCS 9704240051 | |
| Download: ML20140D686 (8) | |
Text
Commonwealth Ediv>n Company 11yron Generating Station 4450 North German Church Road liyron. lL 610149794
. TelHi&2344161 April 11,1997 LTR: BYRON-97-5081 FILE: 2.01.0700 U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attention: Document Control Desk
Subject:
Request for Temporary Relief from ASME Section III Requirements -
Use of Line Stopping Equipment on Essential Service Water ASME Class 3 Piping Byron Nuclear Power Station, Units 1 and 2 Facility Operating Licenses NPF-37 and NPF-66 NRC Docket Nos. 50-454 and 50-455 Pursuant to 10 CFR 50.55a(a)(3), Commonwealth Edison (Comed) is hereby requesting temporary relief for Byron Nuclear Generating Station Units 1 and 2 from the requirements of the 1974 Edition of American Society of Mechanical Engineers (ASME)
Boiler & Pressure Vessel Code,Section III, Subsections NA and ND, Articles NA-3700, ND-2100, ND-3100, ND-3500, and ND-4100. The relief request is being submitted to allow Comed to temporarily install mechanical line stopping equipment in individual 24" diameter Essential Service Water (S)Q cooling tower cell return piping lines. This would allow for replacement of the cooling tower 24" diameter carbon steel riser piping with stainless steel piping and allow for the change out of each corresponding riser isolation motor operated valve (OSX163A-H). Installation of cooling tower stainless steel riser piping and refurbishment of the riser isolation valves will provide significant improvement in the material condition of the safety-related SX cooling tower at Byron Station.
Byron Station requests that this relief request be approved in a timely manner.
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i If there are any additional questions, please contact Marcia Lesniak, Nuclear Licensing
- Administrator, at (630)-663-6484.
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l Sincerely, i
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- )2td David B. Wozniak Engineering Manager.
Byron Nuclear Station Attachment A: Byron Station Temporary Relief Request from ASME Section 111 Requirements - Use of Line Stopping Equipment on Essential Service Water ASME Class 3 Piping Attachment B: Byron UFSAR Figure 9.2-2 sh.11 J
A.B. Beach,. Regional Administrator - Rlli cc:
G.F. Dick,Jr., Byron Project Manager - NRR S.D. Burgess, Senior Resident Inspector - Byron l
Office of Nuclear Safety-IDNS i
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ATTACHMENT A Request for Temporary Relief from ASME Section III Class 3 Requirements for Byron Essential Service Water Cooling Tower Piping Lines Stop Installation.
Pursuant to 10 CFR 50.55a(a)(3), Commonwealth Edison (Comed) is hereby requesting temporary relief for Byron Nuclear Generating Station Units 1 and 2 from the requirements of the 1974 Edition of American Society of Mechanical Engineers (ASME) i_
Boiler & Pressure Vessel Code,Section III, Subsections NA and ND, Articles NA-3700, ND-2100, ND-3100, ND-3500, and ND-4100. The relief request is being submitted to allow Comed to temporarily install mechanical line stopping equipment in individual safety-related Essential Service Water (SX) cooling tower cell return piping lines. The temporary line stop equipment will be installed sequentially in each of eight SX piping lines, over a period of approximately four to five days for each line stopping iteration.
The line stopping equipment would temporarily isolate SX riser piping and a single cooling tower cell, from the remaining seven cooling tower cells and basin. This would allow for replacement of the 24" diameter carbon steel riser piping with stainless steel piping and to allow for the replacement and refurbishment of each corresponding riser isolation motor operated valve (0SX163A-H). The piping replacements are planned because Byron Station has determined that the minimum remaining life for the carbon l
steel riser piping is approximately five years. In addition, all eight riser isolation valves have shown some degree of reduction in performance, which is causing operational difficulties in isolating individual SX riser lines, particularly during winter operation.
Therefore, installation of stainless steel riser piping and replacement / refurbishment of the riser isolation valves will significantly improve the materiel condition of the SX cooling tower piping and improve the operation of the cooling tower riser isolation valves.
The permanently installed line stop fittings, including the 16" diameter piping, flanges, and saddle material, will be installed in accordance with 1974 Edition of ASME Boiler &
Pressure Vessel Code,Section III, with Addenda and Code Cases in effect up to and including Summer 1975 Addenda.
This relief request will demonstrate, per 10 CFR 50.55a(a)(3)i, that the proposed temporary installation of piping line stops will provide an acceptable level of quality and safety.
I.
COMPONENT FOR WHICH RELIEF IS REQUESTED Essential Service Water (SX) Cooling Tower Return Piping The components for which temporary reliefis requested are piping lines OSX97AA-24, USX97Alb24, OSX97AC-24, OSX97AD-24, OSX97AE-24, OSX97AF-24, OSX97AG-24, and OSX97AH-24 (see attached Byron UFSAR Figure 9.2-2 sh.11). The lines run underground between the Auxiliary Building and the SX Cooling Tower Basin, returning SX system water from the plant to the basin. The affected piping components provide a passive pressure boundary
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for the SX Cooling Tower at Byron Station, per the requirements of ASME Section 111, Class 3. The SX Cooling Tower Basin is the primary component of the Ultimate Heat Sink (UHS) for Byron Station.
II.
CODE REQUIREMENT FROM WHICH RELIEF IS REQUESTED Per the requirements of 10 CFR 50.55a(a)(3)(c), Quality Group C components must meet the requirements for Class 3 components in Section 111 of the ASME Boiler & Pressure Vessel Code. The affected components listed in Section I of this document are safety-related, Quality Group C. The components are constructed to meet the requirements of ASME Section III,1974 Edition, up to and including Summer 1975 Addenda. Article NA-3700 requires material manufacturers and suppliers to have a Quality System Certificate and Certified Materials Test Reports. Article ND-2100 requires that pressure retaining materials conform to the requirements of Tables I-7.0 and I-8.0 of Appendix I and a Certified Material Test Report be provided. Article ND-3100 defines the loading criteria for design conditions. In particular, subarticle ND-3112.3(b) requires the effects of earthquakes to be considered in the design of components.
Article ND-3500 requires the use of ASME material specifications for valves.
1 Article ND-4100 requires the component manufacturer to certify by application of the appropriate Code symbol and completion of the appropriate Data Report in accordance with NA-8000. ND-4100 also requires certification of treatments,
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tests, and examinations.
i III.
PROPOSED ALTERNATIVE TO CODE REQUIREMENTS As an alternative to the ASME Section 111 requirements, Comed proposes to install temporary line stop equipment which is designed and built to meet the temperature and pressure requirements of ANSI B16.5, Class 150. The line stop equipment will be provided by TDW Sersices, Inc., a vendor certified to International Organization for Standardization (ISO) 9001 and 9002 Quality Systems - Model for Quality Assurance. TDW Services is the only hot tapping and plugging company in the world that is known to have obtained this quality control certification.
In addition, Byron Station will implement a compensatory action, during the temporary line stop installation, to maintain elevated water levels in the SX Cooling Tower Basin, to ensure sufficient water is available to mitigate the consequences of a temporary line stop failure. Finally, thorough job planning, on-line risk assessment, and operator briefing will be implemented for each iteration of the temporary condition to enhance overall plant safety. This will ensure that operators are fully aware of the necessary actions to be taken following a postulated failure of the line stop m provide cooling tower riser piping isolation.
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1 IV.
BASIS FOR RELIEF Pursuant to 10 CFR 50.55a(a)(3), temporary reliefis requested on the basis that i
the proposed alternatives provide an acceptable level of quality and safety.
Com".d has determined that the temporary line stop equipment provides an equivalent alternative to the current ASME Section 111 requ.irements, for the planned temporary iterations. The original safety-related components within the SX system were designed per ASME Section 111, Class 3 or equivalent codes and standards, based on the criteria in ANSI N18.2a-1975. This criteria was used in
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the design and classification of the Byron Station SX system and components, as a supplement to Regulatory Guide 1.26 criteria.
The temporary line stop equipment has been designed and tested, by the vendor, at higher pressures than the maximum anticipated pressure in the riser piping, at the location of the temporary line stop installation. For the anti;ipated SX syytem operating configuration, the calculated maximum differential pressure across the nearby dawastrum riser isolation valves (0SX163A-H) is 26 psig, which is significantly lower than the rated pressure of 150 psig for the 24" i
diameter line stop plugging head. It is also less than the maximum rated working pressure of 275 psig for the line stop sandwich valve, hot tapping machine, plugg ng machine, and 16" diameter temporary flange plug. The line stopping j
i equipment is rated for a maxirm.m temperature of 180 F. The SX piping was originally qualified to a desir n :ssure of 125 psig and r design temperature of
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140 F.
Post installation verification ofline stopping equipment integrity will be verified prior to removing the riser isolation valves (0SX163A-H) and their associated downstream piping. The line stop equipment will be seismically restrained to prevent damaging the safety related SX piping system during a design basis earthquake. In addition, ASME Section Ill, Class 3 blind flanges will be available on site, to be installed in place of the line stop equipment,if a failure were to ocrm. hat required isolation of the cooling tower return line. A specia!
ne will be implemented which directs the work activities and provides
- e to station operators for the appropriate actions to take in the event of r.
failure of the line stop.
Therefore, Comed has determined that the installation of the temporary line stop condition provides an acceptable level of quality and safety, with respect to the ASME Section 111 requirements. This argument is further supported by the j
installation inspections, compensatory actions, and operator briefimgs that will be i
implemented during each lire stopping iteration.
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0 The UHS for 13yron Station is required to be operable in all modes of operation.
f The Byron Station Technical Specifications do not allow the SX Cooling Tower A or 13 trains to be isolated long enough to allow the scheduled work to be completed without shutting down and defueling both units. There is to existiag isolation capability for the section of piping that is the subject of this relief request. Also, Comed knows of no line stop vendors that can provide their
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equipment as ASME Section 111, Class 3 material. Therefore, relief from the
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requirements of ASME fection 111 is required to perform the scheduled maintenance activities.11elaying or not performing the scheduled maintenance i
would prevent a significant improvement in the materiel condition of the SX Coohng Tower riser piping. Over the long term, this would represent a net l
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decrease in plant cuality.
In summary, Comed believes that this relief request is justified per tne provisions of 10 CFR 50.55a(a)(3) in that the proposed alternative temporary installstion provides ar acceptable level of quality and safety.
V.
PERIOD FOR WHICH RELIEF IS REQUESTED Reliefis requested for eight temporary periods, during which the eight riser isolation valves (OSX163A-H) will be changed out and eight sections of riser piping will be replaced. Each indisidualline stop iteration on a section of riser piping is anticipated to have a duration of approximately four to five days.
Comed anticipates that ch.uled temporary line stop and piping replacement work will occur over approximately 36 months, with the work planned for spring and fidl non-outage periods.
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'O BYRON STATION UPDATED FINAL SAFETY ANALYSIS REPORT p 42 7 RD. P ATTACHMENT E FIGURE 9.2-2 ESSENTIAL SERVI:E CTE: SYSTEU
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