ML20043E314

Withdraws 880302 Application for Amend to Licenses NPF-37, NPF-66,NPF-72 & NPF-77,changing Tech Spec 4.6.1.6.1.d to Reduce Containment Tendon Design Stresses to Incorporate Addl Design Margin,Due to Insufficient Available Data

ML20043E314
Person / Time
Site:	Byron, Braidwood
Issue date:	05/31/1990
From:	Hunsader S COMMONWEALTH EDISON CO.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
1042T, NUDOCS 9006120287
Download: ML20043E314 (2)

Text

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\/Commonwealth Edison

. 1400 Opus Plac) i

• [\ Z ) Downers Crove, Illin:Is 60516 [

%J May 31, 1990 ,

r Dr. Thomas E. Murley Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Attn Document Control Desk

Subject:

Byron Station Units 1 and 2 Braidwood Station Units 1 and 2 Supplement to Application for Amendment to '

Facility Operating Licenses NPF-37, NPF-66 NPF-72 and NPF-77, Appendix A, Technical Specifications NRC Docket No.s 50-454, 50-455, l

50-456 and 50-457

References:

(a) March 2, 1988 S.C. Ilunsader letter to T.E. Murley (b) June 22,1988 L. 01 shen letter to !!. Bliss.

(c) February 23, 1989 L. 01shan letter to !!. Bliss.

Dear Dr. Murley:

1 In reference (a) pursuant to 10 CFR 50.90 Commonwealth Edison (Edison) proposed to amend Appendix A, Technical Specifications, of Facility j Operating Licenses NPF-37 NPF-66, NPF-72 and NPF-75 (now NPF-77). The proposed amendment requested a change to Technical Specification 4.6.1.6.1.d ]

to reduce the containment tendon design stresses to incorporate additional l design margin not reflected in the values currently included in the Byron and Braidwood Technical Specifications.

The NRC staff provided a request for additional information in reference (b) that was answered during a meeting held at White Flint on August 2, 1988. Reference (c) provided the NRC staff's conclusions from that meeting which are stated below: I l

"On August 2, 1988, a meeting was held to discuss the issue. You j presented background information for determining the containment '

tendon design stresses and answered most of our questions regarding the design process of tendons and calculation of tendon forces.

Flowever, you did not address our concern of loss of ultimate strength ,

as time lapses and the rate of relaxation and creep. We would like to )

l continue to monitor the situation closely to determine if there will l be a rapid loss of tendon strength due to concrete 9006J2o207 90o333 N

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Dr. Thomas E. Murley May 31, 1990 creep, corrosion and breakage of wires. We need additional data from future inspections to assess the actual rate of relaxation of tendon strength and to determine that the tendon forces will not decrease below their design forces during plant life."

To address the NRC staff conclusions the results of a significant number of tendon stress surveillances will be needed over a number of years.

As a result, Edison is withdrawing this request for an amendment so that the application need not be carried as "open" for an extended period of time. At that time when sufficient tendon stress surveillance information is available, Edison will make an appropriate amendment application.

Edison is notifying the State of Illinois of this withdrawing of an application for amendment by transmitting a copy of this letter and its  !

attachments to the designated State Official.

Copies of references (a), (b) and (c) are enclosed. Please direct any questions you may have concerning this submittal to this office.

Very truly yours,

,dc W&

S.C. Hunsader Nuclear Licensing Administrator

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Enclosures:

1 Reference (a), March 2, 1988 S.C. Hunsader letter to' T.E. Murley l Reference (b), June 22, 1988 L.N. 01shan letter to H. Bliss Reference (c) February 23, 1989 L.N. 01shan letter to H. Bliss cc Resident Inspector-Byron Resident Inspector-Braidwood P.C Shemanski-NRR S.P. Sands-NRR W. Shafer-Region III M.C. Parker-IDNS i

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,,/ February 23. 1989 Docket Nos. 50-454, 50-455, l 50-456, and 50-457 "j p Mr. Henry E. Bliss

l. Nuclear Licensing Manager

' Cosenonwealth Edison Company Post Office Box 767 Lhicago, Illinois 60690

Dear Mr. Bliss:

L

SUBJECT:

AMENDMENT' REQUEST Oh CONTAINMENT TENDON DESIGN STRESS -

BYRON /BRAIDWOOD (TAC NOS. 67448, 67449, 67450 AND 67451)

By letter dated March 2,1988, you proposed an anendment to the Technical Specif tcetion Section 4.6.1.6.1.d for Byron and Braidwood that would reduce the containment tendon design stress values. We asked for additional information in our June 22, 1988 letter.

Un August 2, 1988, a meeting was held to discuss the issue. You presented b,.ckground information for determining the containment tendon design stresses cud answered most of our questions regarding the design process of tendons and calculation of tendon forces. However. vou did not address our concern of loss of ultimate strenoth as time lapses and the rate of relaxation and

.Lr, g,g We would like to continue to monitor the situat' ion closely to determine if there will be a rapid less of tendon strength due to concrete creep, corrosion and breakage of wires. We need additionel det a f r'un. t otur e seisoe.M om to assess the actual raw of relaxotion of tencon streraith eno to s te rnve int the' tendon forces wit not decrease below their design forces durina olant hfe.

. Therefore, we i re deferrinc our decision on your proposed amendownt until we gain more know' edge on the trend of tendon relaxation through more lif t-off tests of containment tendons in future inspections.

Sincerely,

. C 4 Leona d N. Olshan, Project Manager Project Directorate 111-2 Division of Reactor Projects !!1, IV, V, and Special Projects Office of Nuclear Reactor Regulation cc: See next page N YQ hk'

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• Mr. Henry Bliss Byron /Braiowood Power Station Coutnwenith Edison Compary Units 1 and 2 CC:

Mr. Jack Tain Dr. Eruce von Zellen Atomic Power Distrit,ution Department of Biological Sciences Westinghouse Electric Ccrporation f.'erthern Illinois Unive rsity Fost Office Box 355 Dekelb, Illinois 61107 Pittsburgh, Pennsylu nia 15230 U. S. Nuclear Regulatory Consnission Joseph Gallo Esq. Byron / Resident inspectors Offict Hopkitis and Sutter 4448 North German Church Road 1050 Connecticut Ave., H.W. Byron, Illinois 61010 Suite 1250 Washington, D.C. 20036 Ms. Lorraine Creek Rt. 1, Box 182

-C. Allen Bock, Esquire Manteno, Illinois 60950 Post Office Box 342 Urbana, Illinois 61801- Mrs. Phillip B. Johnson 1907 Str6tford Lane Regional Aon.inistrator Pockforo, Illinois 61107 -

U. S. NRC, Region 111 799 Poosevelt koad, Bldg. #4 Douglass (,assel, Esq.

Glen Ellyn, Illinois 60137 109 N. Dearborn Street Suite 1300 l Ms. Bridget Little Rorem Chicago, Illinois 60602 l Appleseed Coordin6 tor 117 horth Linden Street Ms. Pat Morrison Essey, Illinois 60935 913 N Main Street 6707 Rockford, Illir.cis 61103-7058 Mr. Edward R. Crass '

Nuclear Safeguards and Licensing David C. Thmas, Esq.

Divisich 77 S. Wacker Drive Sargent & Lunay Engineers Chicago, Illinois 60601 55 East Monroe Street Chicago, Illinois 00603 Mr. Charles D. Jones, Director lilinois Emergency Services i U. S. Nuclear Regulatory Connission dnd Disaster Agency l

Resident Inspectors Office 110 East Adams Street RR#1, Box 79 Springfielo, Illinois 62706 Braccville, Illinois 60407 l

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fir. Henry E. Bliss Byron /Braidwced Comorvtalth Edison Company CC:

itr. Michoel C. Parker, Chief -

Division of Engineering ,

Illiricis Departrwnt of Nuclear Safety 1035 Outer Park Orive Springfield, Illinois 62704 Michael Hiller, Esq.

Sidley and Austin One first National Plaze Chicago, Illinois 60603 George L. Edgar New.on & Holtzinger, P.C.

1615 L Street, N.W.

Washington, D.C. 20036 Comenwealth Edison Company Byron Station Manager 4450 North German Church Road Byren, Illinois 01010 i

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,/ June 22, 1988 i Docket Nos. STN 50-454 STN 50-455, STN 50-436 and STN 50-457 Mr. Henry Bliss fluclear Licensing Parager comonwealth Edison Company Post Office Box 761 Chicago, Illinois 60690 ,

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION - CONTAINMENT TENDON DESIGN STRESSES-BYRON /BRAIDWOOD (TAC NOS. 67448, 67449, I

67450AND67451)

By letter dated March 2,1988, you requested an amendment to the Technical Specifications for Byron /Braidwood that would reduce the containment tendon design stresses. Enclosed is a request for additional information. Please respond within 60 days of receipt of this letter.

The reporting and/or recordkeeping requirements contair.ed in this letter affect fewer than ten respondents; therefore OMB clearance is not required under P;L.96-511.

Sincerely,

% M ts Leonard Olshan, Project Manager Project Directorate III-2 Division of Reactor Projects - III IV, V and Special Projects

Enclosure:

As stated cc: See next page

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Mr. Henry Bliss

! Connonwealth Edison Company Byron /Braidwood L

l CC' Mr. William Kortier Dr. Bruce von Zellen ,

Atomic Power Distribution Department of Biological Sciences Westinghouse Electric Corporation Northern Illinois University Post Office Box 355 DeKalb, Illinois 61107 Pittsburgh, Pennsylvania 15230 Joseph Gallo, Esq. V. S. Nuclear Regulatory Connission

Hopkins and Sutter Byron / Resident inspectors Office 1050 Connecticut Ave., N.W. 4448 German Church Road Suite 1250 Byron, Illinois 61010 Washington, D. C. 20036 Ms. Lorraine Creek l

C. Allen Bock, Esquire Rt. 1, Box'182 Post Office Box 342 Manteno, Illinois 60950 Urbana Illinois 61801 Mrs. Phillip B. Johnson Regional Administrator 1907 Stratford Lane U. S. NRC, Region 111 Rockford, Illinois 61107 799 Roosevelt Road l Glen Ellyn, Illinois 60137 Douglass Cassel Esq.

109 N. Dearborn Street Ms. Bridget Little Rorem Suite 1300 .

Appleseed Coordinator Chicago, Illinois 60602 l 117 North Linden Street L Essex, Illinois 60935 Ms. Pat Morrison l 5568 Thunderidge Drive -

Mr. Edward R. Crass Rockford, Illinois 61107 l Nuclear Safeguarcs and Licensing Division David C. Thomas. Esq.

Sargent & Lundy Engineers 77 S. Wacker Drive

55 East Monroe Street Chicago, Illinois 60601 i Chicago, Illinois 60603 Elena Z. Kezelis, Esq.

U. S. Nuclear Regulatory Connission Isham, Lincoln & Beale Resident Inspectors Office Three First National Plaza RR#1, Box 79 Suite 5200 Bracev111e, Illinois 60407 Chicago, Illinois 60602 l

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,' June 22, 1988 4

i Enclosure Request fer Additional Informatio_n

1. Provide background information, including basic assumptions, calculation and test results, for the determination of the original minimum design value of lift off stresses in tendons and show how the design tendon stresses (i.e.,143 ksi for dome,14a ksi for vertical and 140 ksi for hoop) were determined in the technical specification.

2. Provide analysis, calculation and test results to show how the proposed design tendon stresses (133 ksi for come,127 ksi for vertical and 133 ksi for hoop) are obtained.

3. Describe how the reduction of design stresses will affect the margin cf safety, and provide justification for such reduction by assuring that the structural integrity of the containment will not be impaired in any 'aay.

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• *'. fN) Commonwealth Edloon One FC National Pwa CNeago. Ilknors I l Adress Repy to Post O.ce Bon 7C l k(,

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March 2, 1988 >

t Mr. Thomas E. Murley, Director i Of fice of Nuclear Reactor Regulatior U.S. Nuclear Regulatory Commission Washington, DC 20$$$ .

I Attn Document Control Desk

Subject:

Byron Station Units 1 and 2 .

l Braidwood Station Units 1 and 2 .

Application for Amendment to Facility Operating Licenses NPF-37, NPP-66.

NPF-72, and NPP-75 ,

Appendix A. Technical Specifications

,- NRC Docket Nos. 50-454. 50-455, 50-456 and 50-457 1

Dear Mr. Murley:

I Pursuant to 10 CPR 50.90 Commonwealth Edison proposes to amend Appendix A, Technical Specifications, of Facility Operating Licenses NPF-37, 1;

WPF-66, WPF-72 and NPF-75. The proposed amendment requests changes to Technical Specification 4.6.1.6.1.d. to reduce the containment tendon design stresses to incorporate additional design margin not reflected in the values  !

currently in the Technical Specifications.

The revised Technical Specification pages are contained in Attachment A. The description and summary of the proposed changes is

• l presented in Attachment B.

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! The proposed changes have been reviewed and approved by both on-site and off-site review in accordance with Commonwealth Edison procedures. Commonwealth Edison has reviewed this proposed amendment in accordance with 10 CFR 50.92(c) and has determined that no significant  ;

hazards consideration exists. This evaluation is documented in Attachment C.  ?

Byron Station is scheduled to performed this surveillance in June,  ;

1988 on Units 1 and 2. Braidwood Station is scheduled to perform this surveillance in September, 1988 on Unit 2 and May, 1989 for Unit 1.

Therefore, NRC review and acceptance to support this schedule-is requested.

Commonwealth Edison is notifying the State of Illinois of our application for this amendment by transmitting a copy of this letter and its attachments to the designated State Official.

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March 2. 1968 US WRC i

In accordance with 10 CFR 170, a fee remittance in the amount of

$150.00 is enclosed.

Please direct any questions you may have concerning this matter to this office.

Very truly yours, i

I- I S. C. Hunsader Nuclear Licensing Administrator 4

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Enclosure:

Fee Remittance Attachments (A): Proposed Technical Specification Changes (B): Description and Summary (C): Evaluation of Significant Hazards consideration cct Resident Inspector - Byron Resident Inspector - Braidwood L. N. Olshan - NRR S. Sands - NRR Region III office M. C. Parker - State of Ill.

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ATTACHMENT 4 PROPOSED CHANGES TO APPENDTX A, TECHNICAL SPECIFICATIONS OF 7ACILIJTl OPERATING LICENSES WPF-37. WPF-66. NPF-72 and NPF *15 Byron Station Braidwood Station Fevised Pages: 3/4 6-9 Revised Pages: 3/4 6-9 i

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7 CONTAINMENT SYSTEMS l

$URvEILLANCE REQUIREMENTS (Continued)

b. Performing tendon detensioning, inspections, and material tests on '

i a previously stressec tencon from each group (come, vertical, and '

l hoop). A randomly selected tendon from each group shall be completely detensioned in orcer to identify broken or damaged wires and deter-mining that over the entire length of the removed wire or strane that: l

1) The tendon wires or strands are free of corrosion, cracks, and ,

damage, i

2) There are no changes in the presence or physical appearance of i the sheathing filler grease, and *

3) A minimum tensile strength of 240,000 psi (guaranteed ultimate  ;

strength of the tendon material) for at least three wire or strand samples (one from each end and one at mid-length) cut from each removed wire or strand. Failure of any one of the wire or strand samples to meet the minimum tensile strength test i is evidence of abnormal degradation of the containment vessel  ;

structure. I

c. Performing tendon retensioning of those tendons detensioned for inspection to their observed lift-off force with a tolerance limit of +6%. During retensioning of these tendons; the changes in load ,

and elongation should be measured simultaneously at a minimum of three approximately equally spaced levels of force between zero and the seating force. If the elongation corresponding to a specific load differs by more than 5% from that recorded during. installation,  :

an investigation should be made to ensure that the difference is not related to wire failures or slip of wires in anchorages;

d. Assuring the observed lift off stresses adjusted to account for elastic losses exceed the average minimum design value given below:

Dome 133149 ksi Vertical 12*lt44 ksi .

Hoop I 3344G _ ksi

e. Verifying the OPERABILITY of the sheathing filler grease by assuring: I

1) No voids in excess of 5% of the net duct volume,

2) Minimum grease coverage exists for the different parts of the anchorage system, and .

3) The chemical properties of the filler material are within the tolerance limits as specified by the manufacturer.

BYRON - UNITS 1 & 2 3/4 5-9

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CONTAINMENT SYSTEMS SURVEILLANCE REOUIREMENTS (Continued)

, b. Performing tendon detensioning, inspections, and material tests on a previously stressed tendon from each group (dome, vertical, and hoop). A randomly selected tendon from each group shall be completely de? 9sioned in order to identify broken or damaged wires and deter-mining that over the entire length of the removed wire or strand that:

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1) The tendon wires or stran's d are free of co'rrosion, cracks, and damage,

2) There are no changes in the presence or physical appearance of the sheathing filler grease, and

3) A minimum tensile strength of 240,000 psi (guaranteed ultimate strength of the tendon material) for at least three wire or strand samples (one from each end and one at mid-length) cut from each removed wire or strand. Failure of any one of the wire or strand samples to meet the minimum tensile strength test is evidence of abnorma1' degradation of the containment vessel structure. *

c. Performing tendon retensioning of those tendons detensioned for inspection to their observed lift-off force with a tolerance limit of +6%. During retensioning of these tendons, the changes in load and elongation should be measured simultaneously at a minimum of three approximately equally spaced levels of force between zero and the seating force. If the elongation corresponding to a speci)1c load differs by more than 5% from that recorded during installation, an investigation should be made to ensure that the difference is not related to wire failures or slip of wires in anchorages;

d. Assuring the observed lift-off stresses adjusted to account for elastic losses exceed the average minimum design value given below:

Dome 133 Mt ksi l Vertical p q 444 ksi Hoop ) y M6 ksi

e. Verifying the OPERABILITY of the sheathing filler grease by assuring:

1) No voids in excess of 5% of the net duct volume,

2) Minimum grease coverage exists for the different parts of the anchorage system, and'

3) The chemical properties of the filler material are within the tolerance limits as specified by the manufacturer.

BRAIDWOOD - UNITS 1 & 2 3/4 6-9

ATTACHMENT B DESCRIPTION AND SUP9tARY_ OF PROPOSED CHANGES l

l The proposed changes involve Technical Specification 4.6.1.6.1.d for the Byron and Braidwood Stations.

Basis for-Changes to Tendon Design Stress Values

, The design tendon stresses for Byron /Braidwood containments I specified in the current Technical Specification can be reduced as follows:

i' Dome from 143 ksi to 133 ksi Vertical from 144 ksi to 127 ksi Hoop from 140 ksi to 133 ksi Original Design Basis The containment tendon forces be. lance loads, in particular ,

pressure, that put the containment shell in tension. The tendon force must be suf ficient to balance the tension forces to keep the reinforcing steel l within the allowable stresses.

Two load combinations and load factors given in Table 3.8-3 of the PSAR which control the design of the tendon forces are:

l For hoop and dome tendons:

Abnormal: 1.5P a =Ta (LE) - D Por vertical tendon:

Abnormal / Severe Environmental: 1.25 (Pa + (OBE) + Ta (LE) - D where Pa = the design internal pressure of 50 psig Ta (LE) = liner expansion effect due to temperature dif ference between liner and concrete  :

OBE = Operating Basis Earthquake D = Dead Load

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Basis for Revision The new design stress values were derived by taking into account the following refinements that had not been considered in the original design values.

1. Additional Tendon Forces @ P a Force in the tendons increase corresponding to the outward deflection of the wall when internal accident pressure (P a ) is applied.

Compatibility dictates that the tendons are extended by the outward deflection due to the pressure. Additional tendon forces of 1.73%,

1.75%, and 3.8% of the forces produced by P, are accounted for dome, vertical and hoop tendons respectively. They are based on the deflections observed during the Structural Integrity Tests. .

2. Reduction in Liner Expansion Force @ Pa The applied internal accident pressure, pa . also extends the liner.

The liner is at a higher temperature than the concrete and When it tries to expand it puts the concrete in tension. The extension of the liner due to p, relieves the liner expansion forces assumed in the original design for dome, vertical and hoop tendons, respectively, by 10%, 25%,

and 184. The required tendon forces in the wall are consequently reduced.

3. Use of Refined Seismic Analysis The containment seismic forces used in the original tendon design were calculated assuming a maximum overturning moment obtained from a simplified seismic " stick model" was applied over the containment wall sections. The seismic forces can be reduced by 13% for the section at the basemat-wall junction when the refined DYNAX seismic model which utilizes a 3-dimensional analysis is used. This substantially reduces the force required in the vertical tendons.

ATTACHMENT C EVALUATION OF SIGNIFICANT HAZARDS CONSIDERATIONS commonwealth Edison has evaluated this proposed amendment and determined that it involves no significant hazards considerations.

According to 10 CFR 50.92(c), a proposed amendment to an operating license involves no significant hazards considerations if operation of the facility in accordance with the proposed amendment would not:

1) Involve a significant increase in the probability or consequences of an accident previously evaluated; or

2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or

3) Involve a significant reduction in a margin of safety.

The proposed amendment of specification 4.6.1.6.1.d reduces the >

l containment tendon design stresses to incorporate additional design margin The not reflected in the values currently in the Technical specifications.

l design stresses provided in the Technical Specifications correspond to the average tendon stress after 40 years of losses. Losses occur due to relaxation it,the tendon wires and shrinkage and creep in the concrete.

Most of these losses occurred in the first few years after the tendons were stressed (1980 to 1982 at Byron and Braidwood). Thus the predicted tendon force determined when performing the Technical Specification surveillances can approach the design force. The difference between the calculated tendon force and the design force is small enough that factors such as different methodologies for performing lift-offs at installation and at the in-service inspection and tolerances on the equipment can result in tendon forces at variance with technical specification valves. When these limits are not I met, the Technical Specifications require that the containment integrity be restored, an engineering evaluation be performed and a special report be submitted to the Commission or that the station be shutdown.

The new design stress values were derived by taking into account such factors as additional tendon forces based on the deflections observed during the Structural Integrity Tests and reduction in the liner expansion force which consequently reduces the tendon forces in the containment wall.

Also the vertical tendon forces were reduced by the use of a refined DYNAX seismic model which uses a three-dimensional analysis. The proposed reduced design stresses will provide a larger margin between the expected tendon forces and the Technical specification values.

The proposed amendment does not involve a significant increase The in the probability or consequences of an accident previously evaluated.

changes do not alter the existing tendon stresses or the containment system. They merely incorporate new design stress values as determined by the Architect / Engineer based on refinements not included in the original design basis. The new design stress values meet the Byron and Braidwood PSAR acceptance criteria for use in monitoring containment prestressing.

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The change does not add or modify any existing equipment, nor introduce a new mode of plant operation. The containment tendon lift-off stresses will continue to be verified in accordance with Technical '

Specification 4.6.1.6.1.d., The containment system remains in its as-built configuration and the design 1s in accordance with the Byron and Braidwood '

FSAR acceptance criteria. As such, the possibility of a new or different kind of accident from any accident previously evaluated is not created.

The proposed amendment does not involve a significant reduction in a margin of safety. The containment structure and the existing tendon stresses remain unchanged. The revision establishes new tendon design '

stress values for monitoring the prestress. In addition, this ensures the .

containment maintains its integrity following an accident that generates an internal design pressure.

The new values were prepared in accordance with The new design the acceptance criteria in the Byron and Braidwood FSAR.

stress values were determined in accordance with accepted methodologies so the margin of safety is not impacted.

Therefore based on the above analysis Commonwealth Edison concludes that the proposed amendment to the Technical Specification does not involve significant hazard considerations.

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