ML20216D796

Requests Temporary Relief for Plant from Requirement of 1974 Edition of ASME Boiler & Pressure Vessel Code,Section III Re Use of Line Stopping Equipment on Essential Svc Water ASME Class 3 Piping

ML20216D796
Person / Time
Site:	Byron
Issue date:	03/02/1998
From:	Kofron K COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BYRON-98-5054, NUDOCS 9803170278
Download: ML20216D796 (8)

Text

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O)mmonwealth Illison O)mpany lly ron Generating St.ition 4 650 North Gernan Church ituad fly ron. 11.61010 9794 Tel1415-231511I March 2,1998 LTR: BYRON-98-5054 FILE: 2.01.0700 U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attention: Document Control Desk

Subject:

Additional Request for Temporary Relief from ASME Section III Requirements - Use of Line Stopping Equipment on Essential Sersice 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

Reference:

1. " Request for Temporary Relief from ASME Section 111 Requirements -

Use ofLine Stopping Equipment on Essential Senice Water ASME Class 3 Piping," Byron letter 97-5081, D. B. Wozniak to NRC Document Control Desk, dated April 11,1997 and supplemented on July 10,1997.

2. " Temporary Relief From ASME Section III Requirements; Use ofLine Stopping Equipment on Essential Senice Water ASME Class 3 Piping; Byron Station, Units 1 and 2 (TAC Nos. M98514 and M98515)," NRC Safety Evaluation Report, R. A. Capra (NRC) to 1. M. Johnson (Comed), dated October 3,1997.

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. In Reference 1, Comed requested relief to install temporary line stopping equipment in eight individual 24" lines in the Essential Service Water (SX) Cooling Tower cell return piping lines. NRC approved Comed's request as documented in Reference 2. This additional teliefrequest (Attachment A) is , .I being submitted to expand the scope of the planned maintenance activity for two of the individual iterations to allow Comed to temporarily install mechanical line stopping v ,gL ' f 3

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equiprnent in two individual 48" diameter SX cooling tower cell return piping lines. This j

' would still allow for replacement of the cooling tower 24" diameter carbon steel riser piping with stainless steel piping for the two affected cells and the change out of each corresponding riser isolation motor operated valve (0SX163D and H). In addition, it

.would allow for replacement of the cooling tower hot water bypass isolation valves in pairs of two during each individual iteration, OSX162A/C and OSX162B/D, respectively.

Replacement of the cooling tower riser piping, the riser isolation valves, and the hot water bypass valves will provide significant improvement in the materiel condition of the safety-  ;

related SX cooling tower at Byron Station.

Byron Station requests that this relief request be approved in a timely manner to support cooling tower work currently scheduled to begin in September,1998,

, if there are any additional questions, please contact Marcia Lesniak, Nuclear Licensing Administrator, at (630)-663-6484.

Sincerely, I

, s-K. L. Kofron 1 Station Manager ]

. Byron Nuclear Power Station j KLK/BA/cb Attachment A: Byron Station Temporary Relief Request from ASME Section III Requirements - Use of Line Stopping Equipment on Essential Service Water ASME Class 3 Piping Attachment B: Byron UFSAR Figure 9.2-2, sheet 11

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cc: Regional Administrator-RIII Byron Project Manager - NRR Senior Resident inspector - Byron Office ofNuclear 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)

Boiler & Pressure Vessel Code, Section 111, 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 i I

safety-related Essential Service Water (SX) cooling tower cell return piping lines. The temporary line stop equipment will be installed sequentially in two SX piping lines, over a period of approximately five to six days for each line stopping iteration. The line stopping l equipment would temporarily isolate the dual bypass lines and riser for a single SX cooling  ;

tower cell from the remaining seven cooling tower cells and basin. This would allow for: I l

replacement of the downstream 24" diameter carbon steel riser piping with stainless steel piping; replacement and refurbishment of the downstream riser isolation motor operated valves, OSX163D and OSX163H; and replacement of hot water bypass valves OSX162A, D, C and D.

I Previously, Byron Station requested (Reference 1) and was granted temporary relief by l the NRC (Reference 2) from the requirements of the ASME code to allow for replacement f of all eight riser isolation valves and corresponding riser piping. Comed is requesting to expand the scope of that previous relief request for two of the valves, OSX163D and l OSX163H. By moving the temporary line stopping equipment upstream of the previous location for two of the eight iterations, it is possible to isolate the hot water bypass lines as well. This will enable replacement of bypass valves OSX162A and C (in conjunction with riser valve OSX163D) and OSX162B and D (in conjunction with riser valve OSX163H).

The entire scope of piping and valve replacements is planned because Byron Station has determined the minimum remaining life for the carbon steel riser piping is approximately five years. In addition, all eight of the riser isolation valves and four hot water bypass valves bave shown some degree of reduction in performance, which is causing operational difficulties during various plant configurations and ambient conditions. Therefore, installation of stainless steel riser piping and replacement / refurbishment of the riser isolation valves and hot water bypass valves will significantly improve both the materiel condition of piping and configuration flow control for the SX cooling tower.

The permanently installed line stop fittings, including the 36" 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 with the exception that alternate hydrostatic pressure test requirements per Byron Station 2nd 10-year interval Inservice Inspection Relief Request 12R-15 will be utilized for post installation testing. This reliefrequest was AI

, recently approved by the NRC in Reference 3. This alternate pressure test is consistent with ASME Code Case N-416-1, " Alternate Pressure Test Requirement for Welded Repairs or Installation of Replacement items by Welding for Class 1,2, and 3, System,Section XI, Division 1" l

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 OSX03CA-48 and OSX03CB-48. This request only expands the scope of the original request for two of the replacement iterations to allow for the replacement of all four hot water bypass valves in pairs of two, OSX162A/C and OSX1628/D, (see Attachment B for location of proposed line stop locations). With each line stopping iteration, the sequence of events for individual work activities will be scheduled so as to minimize the potential consequences of a faulted line stop.

The SX lines mn underground between the Auxiliary Building and the SX Cooling Tower Basin, returning SX system water from the plant to the basin. Flow is either directed to the SX cooling tower riser valves and piping, or through the hot water bypass valves and lines directly to the basin. The affected piping components provide a passive pressure boundary for the SX Cooling Tower at Byron Station, per the requirements of ASME Section Ill, 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)(e), Quality Group C components j must meet the requirements for Class 3 components in Section 111 of the ASME I Boiler & Pressure Vessel Code. The afTected components listed in Section I of this document are safety-related, Quality Group C. The components are constmeted to meet the requirements of ASME Section Ill,1974 Edition, up to and including Su 1mer 1975 Addenda. Anicle NA-3700 requires material minufacturers and suppliers to have a Quality System Cenificate and Certified Materials Test Reports. Article ND-2100 requires that pressure retaining materials conform to the requirements of Tables I-7.0 and 1-8.0 of Appendix 1 and a Cer'ified Material Test Report be provided. Article ND-3100 defines the loading critetia tbr design conditions. In panicular, subarticle ND-3112.3(b) requires the effec's of earthquakes be considered in the design of components. Article ND-3500 requires the use of ASME material specifications for valves. Anicle ND-A2 1

.. 1 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, tests, and examinations.

111.~ PROPOSED ALTERNATIVE TO CODE REQUIREMENTS As an alternative to the ASME Section 111 requirements, Comed proposes to install temporary line stop equipment which meets or exceeds the temperature and pressure requirements of ANSI B16.5, Class 150. The line stop equipment will be provided by TDW Services, Inc., a vendor certified to International Organization for Standardization (ISO) 9001 and 9002 Quality Systems - Model for Quality Assurance.

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 and 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 to provide cooling tower riser piping isolation.

IV. BASIS FOR RELIEF Pursuant to 10 CFR 50.55a(a)(3), temporary reliefis requested o i the basis that j the proposed alternatives provide an acceptable level of quality and dety. Also, compliance with the current specified requirements would result in a har& hip for l Byron Station without a compensating increase in quality and safety.

Comed has determined that the temporary line stop equipment provides an equivalent alternative to the current ASME Section 111 requirements, 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 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 at higher pressures than the maximum anticipated pressure in the riser piping, at the location of the temporary line stop installation. For the anticipated SX system operating 4 configuration, the calculated maximuni differential pressure across the nearby downstream riser isolation valves (OSX163D and H) is 26 psig, which is significantly lower than the rated pressure of 140 psig for the 48" diameter line A3

9 stop plugging head. The line stopping equipment is rated for a maximum temperature of 1807. The SX piping was originally qualified to a design pressure of 125 psig and a design temperature of 1507.

Post installation verification ofline stopping equipment integrity will be verified prior to removing the riser isolation valves (0SX163D and H), their associated downstream piping, and the SX tower hot water bypass valves. 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 111, Class 3 blind flanges will be available on site to restore system integrity if a failure were to occur that required isolation of the cooling tower return line. A special procedure will be implemented which directs the work activities and provides guidance to station operators for the appropriate actions to take in the event of a failure of the line stop equipment.

Therefore, Comed has determined that the installation of the temporary line stop equipment provides an acceptable level of quality and safety, with respect to the ASME Section III requirements. This argument is further supported by the installation inspections, compensatory actions, and operator briefings that will be implemented during each line stopping iteration. In addition, to date, Byron Station has successfully completed the planned replacements for three of the eight cells per the previously referenced relief request. This provides additional assurance that the planned scope expansion for the two line stop iterations can be accomplished safely.

The UHS for Byron Station is required to be operable in all modes of operation.

The Byron Station Technical Specifications do not allow the SX Cooling Tower A or B trains to be isolated long enough to allow the scheduled work to be completed without shutting down and defueling both units. There is no existing 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 equipment as ASME Section lil, Class 3 material. Therefore, relief from the requirements of ASME Section 111 is required to perform the scheduled maintenance activities.

Delaying or not performing the scheduled maintenance would prevent a significant improvement in the materiel condition of the SX Cooling Tower. Over the long term, this would represent a net decrea.;e in plant quality.

The SX system will be considered fully operable during the course of the modification work. Technical Specification 3/4.7.5," Ultimate Heat Sink"(UHS) requires, in part, that 6 SX fans are OPERABLE (high speed) and that SX pump discharge temperature be 5907. In other words, up to two cells can be unavailable with SX pump discharge temperature 590T and the UHS is considered operable. The modification work will directly affect only one cell at a time with installation of the linestop device at the location noted on Attachment B.

Note that the hot water bypass valves are typically used during cold weather operations in the winter to maintain minimum temperatures in the SX basin. It is A4

e not anticipated that hot water bypass operation will be required during the scheduled replacements. In the event further temperature control at the SX basin I

is required, the alternate train bypass valves wculd be available to plant operators.

l In summary , Comed believes that this relief request isjustified per the provisions l of 10 CFR 50.55a(a)(3) in that the proposed alternative temporary installation provides an acceptable level of quality and safety.

V. PER. LOD FOR WHICH RELIEF IS REQUESTED Reliefis requested for two temporaiy periods, during which the two riser isolation valves (0SX163D and H) along with two sections of riser piping will be replaced

. and four hot water bypass valves in pairs of two (OSX162A/C and OSX162B/D) will be changed out. The relief request is only app!icable to the period of time in I

which the line stopping equipment is credited with maintaining system integrity and not the entire scope of thejob. This time period for reliefis anticipated to have a duration of approximately five to six days during each iteration.

The temporary line stop and piping replacement discussed in this request is i currently scheduled to begin in September,1998. The schedule is planned for this period to allow for plant operations at Byron Station to enjoy greater operational flexibility between Summer and Winter operation of the SX Cooling Tower.

VI. REFERENCES

1. " Request for Temporary Relief from ASME Section 111 Requirements -

Use of Line Stopping Equipment on Essential Service Water ASME Class 3 Piping," Byron letter 97-5081, D. B. Wozniak to NRC Document Control Desk, dated April 11,1997 and supplemented on July 10,1997.

2. " Temporary Relief From ASME Section Ill Requirements; Use of Line Stopping Equipment on Essential Service Water ASME Class 3 Piping; Byron Station, Units 1 and 2 (TAC Nos. M98514 and M98515), NRC Safety Evaluation Report, R. A. Capra (NRC) to 1. M. Johnson (Comed),

dated October 3,1997.

3. "Second 10-Year Inservice inspection Program Relief Requests - Byron Station, Units 1 and 2 (TAC Nos. M94830 and M94831), NRC Safety Evaluation, R. A. Capra (NRC) to O. D. Kingsley, (Comed), dated l January 13,1998.

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