ML20215E403

Forwards Request for Addl Info Re 840618 Request for Exemptions from 10CFR50,App A,Gdc 4 Concerning Accumulator & Pressurizer Surge Line Pipe Breaks.Response Requested within 60 Days of Ltr Date

ML20215E403
Person / Time
Site:	Catawba
Issue date:	10/08/1986
From:	Jabbour K Office of Nuclear Reactor Regulation
To:	Tucker H DUKE POWER CO.
References
NUDOCS 8610150280
Download: ML20215E403 (8)

Text

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Docket No.: 50-414 Mr. H.B. Tucker, Vice President 0 Nuclear Production Department Duke Power Company 422 South Church Street Charlotte, North Carolina 28242

SUBJECT:

CATAWBA NUCLEAR STATION, UNIT 2 - REQUEST FOR ADDITIONAL INFORMATION ON ALTERNATIVE PIPE BREAK CRITERIA FOR THE ACCUMULATOR AND PRESSURIZER SURGE LINES By letter dated June 18, 1984, you requested an exemption to the requirements of 10 CFR 50, Appendix A, General Design Criterion (GDC)-4 for the accumulator line pipe breaks. The staff has reviewed ycur request and finds that additional infomation, identified in Enclosure 1, is needed for completion of its review.

Furthermore, by letter dated May 29, 1984, you requested an exemption to GDC-4 for the pressurizer surge line pipe breaks. The May 29, 1984, letter supplemented your February 29, 1984 letter which provided the technical basis for the above exemption. The staff has also reviewed your submittals and finds that additional infomation, identified in Enclosure 2, is needed for completion of its review.

In addition, we request that the vendor, Westinghouse Electric Corporation, agree to release for each line the system parameters, margin numbers, specific system moments and forces, references to analytical methods, leak rates and reference crack sizes, which have been designated as proprietary. This information must be included in the NRC staff's safety evaluation to support its conclusions. '

Your responses to the enclosures are requested within 60 days from the date of this letter. Please contact me at (301) 492-7367 if you have questions regarding the enclosures or are unable to meet the requested response date.

Sincerely.

061oteo2 ADO g g j8314 Kahtan N. Jabbour, Project Manager PDR PDR PWR Project Directorate #4 P

Division of PWR Licensing-A

Enclosures:

As stated cc w/ enclosures:

See next page DISTRBUTION:

rMP JPartlow MDuncan Local POR BGrimes RBallard NRC PDR Edordan ESullivan PWRf4 Reading NThompson BJYoungblood ACRS(1 OGC-Bethesda KJabbot PWR# DPWR-A PWRphPWR-A g PWR#4 WR-A KJabbour/ rad f!D'uncan BJYoungbloco 10/]/86 10/7 /86 10/7/86

e 4 Mr. H. B. Tucker Duke Power Company Catawba Nuclear Station cc:

William L. Porter, Esq. North Carolina Electric Membership Duke Power Company Corp.

P.O. Box 33189 3333 North Boulevard Charlotte, North Carolina 28242 P.O. Box 27306 Raleigh, North Carolina 27611 J. Michael McGarry, III, Esq.

Bishop, Libennan, Cook, Purcell Saluda River Electric Cooperative, and Reynolds Inc.

1200 Seventeenth Street, N.W. P.O. Box 929 Washington, D. C. 20036 Laurens, South Carolina 29360 North Carolina MPA-1 Senior Resident Inspector Suite 600 Route 2 Box 179N 3100 Smoketree Ct. York, South Carolina 29745 P.O. Box 29513 Raleigh, North Carolina 27626-0513 Regional Administrator, Region II U.S. Nuclear Regulatory Comission, L.L. Williams 101 Marietta Street, NW, Suite 2900 Area Manager, Mid-South Area Atlanta, Georgia 30323 ,

ESSD Projects Westinghouse Electric Corp.

MNC West Tower - Bay 239 P.O. Box 355 Pittsburgh, Pennsylvania 15230 Mr. Heyward G. Shealy, Chief Bureau of Radiological Health NUS Corporation South Carolina Department of Health 2536 Countryside Boulevard and Environmental Control Clearwater, Florida 33515 2600 Bull Street Columbia, South Carolina 29201 County Manager of York County York County Courthouse Karen E. Long York South Carolina 29745 Assistant Attorney General N.C. Department of Justice Richard P. Wilson, Esq. P.O. Box 629 Assistant Attorney General Raleigh, North Carolina 27602 S.C. Attorney General's Office P.O. Box 11549 Spence Perry, Esquire Columbia, South Carolina 29211 General Counsel Federal Emergency Management Agency Piedmont Municipal Power Agency Room 840 100 Memorial Drive 500 C Street Greer, South Carolina 29651 Washington, D. C. 20472 Mark S. Calvert, Esq. Mr. Michael Hirsch Bishop, Libennan, Cook, Federal Emergency Management Agency Purcell & Reynolds Office of the General Counsel 120017th Street, N.W. Room 840 Washington, D. C. 20036 500 C Street, S.W.

Washington, D. C. 20472 Brian P. Cassidy, Regional Counsel Federal Emergency Management Agency.

Region I J. W. McConnach POCH Boston, Hassachusetts 02109

, Enclosure i e

ATTACHMENT REQUEST FOR ADDITIONAL INFORMATION

1. Material Characterization a) For the base and weld metal actually in the Catawba accumulator line provide the mechanical properties (e.g. ultimate and yield strengths) or other significant material properties that will characterize the material.

b) Indicate the type weld and post weld heat treatment used to fabricate the welds in the accumulator line.

3 c) Provide a materials evaluation to demonstrate that the material stress-strain curve in Figure 5-8, J and the J-R curve used in the Ic analyses are representative of the material in the accumulator line. This evaluation should follow the general guidelines in NUREG-1061. Vol. 3, and include a comparison, of the material properties for the accumulator line to the material properties for test data, i

i d) Identify any welded fittings that may be in the accumulator

! injection system.

2. History of Cracking Section 2.0 of WCAP 10537 should include references to NUREG-0691 and NUREG-0531 reports. Also, evaluate the susceptibility of the accumulator

line to stress corrosion and fatigue cracking and water hamer relative to the experience base described in these huREG's. ~

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3. Loads a) List individual axial load and bending moment components used to determine the resultant axial forces and bending moments indicated on page 3-2 of WCAP 10487.

b) Provide a qualitative discussion of why a circumferential flaw in a straight pipe section is more limiting than a longitudinal flaw in an elbow or other component.

4. Stability Analysis / Code Validation a) The stability analysis should meet the margins on load and flaw size in Sections 5.2 (h) and (1) and factor of 10 on leakage discussed in Section 5.7 of NUREG-1061, Vol. 3. The stability analysis should include the pipe and attachment weld materials.

i b) Describe the method of validating (bench marking) each computer 1 code used in the leak rate and fracture mechanics calculations.

5. Leak Rate Analysis a) Describe the computational procedure used to calculate crack opening area.

b) How'were loads combined to detemine the crack opening area in the leak rate calculation? Provide justification that the method of combining loads is conservative.

6. Fatigue Crack Growth Analysis a) The data cited in Reference 8-2 as the basis for the fatigue crack growth rate should be included in the report in graphical form that would illustrate and justify the fatigue crack growth

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,, rate constants in equation 8-4 of WCAP 10487. These equations

, should represent the fatique crack growth rate of the material characterized in item 1.

b) The applicant will perfonn as realistic analysis as possible using service level A and B loads. The aspect ratio for the I

postulated crack in the fatigue evaluation should be 6. The aspect ratio should remain constant throughout the analysis.

Unless otherwise justified the maximum allowable flaw depth is the smaller of:

(1) 60% of the wall thickness, or (2) the depth at which the plastic zone is equal to the remaining ligament.

c) The length of the fatique crack must be less than both:

(1) the length of the instabilits thru-wall crack at /2 (N+SSE) and

, (2) 1/2 (instability thru-wall flaw at N+SSE)

The applicant is requested to confirm that the fatigue analysis includes theitemslistedinb)andc),above.

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i ATTACHMENT REQUEST FOR ADDITIONAL INFORMATION

1. Material Characterization a) For the base and weld metal actually in the Catawba surge I

line provide the mechanical properties (e.g. ultimate and yield

} strengths) or other significant material properties that will f characterize the material.

b) Indicate the type weld and post weld heat treatment used to fabricate the welds in the surge line.

J c) Provide a materials evaluation to demonstrate that the material stress-strain curve in Figure 5-8, the J gg and the J-R curve used '

4 in the analyses are representative of the material in the Catawba surge lines. This evaluation should follow the general guidelines in NUREG-1061. Vol. 3 and include a comparison of the material j properties for the surge line to the material properties for test data.

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d) Identify any cast welded fittings that may be in the pipe system.

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2. History of Cracking i l

Section 2.0 of WCAP 10487 should include references to the NUREG-0691 and NUREG 0531 reports. Also, evaluate the susceptibility of the surge l line to stress corrosion and fatigue cracking and water haniner relative i to the experience base described in these NUREG's.

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3. Loads a) List individual axial load and bending moment components used to detemine the resultant axial forces and bending moments indicated in Table 3-1 of WCAP 10537.

b) Provide a qualitative discussion of why a circumferential flaw in a straight pipe section is more limiting than a longitudinal flaw in an elbow or other component.

4. Stability Analysis a) The stability analysis should meet the margins on load and flaw sizeinSections5.2(h)and(1)andfactorof10onleakage discussed in Section 5.7 of NUREG 1061. Vol. 3.

b) The length of the longest pipe segment between supports may not be appropriate to define the effective pipe length required for computing the applied tearing modulus from equation 5-1 of WCAP 10537. Provide further justification to demonstrate that the calculated applied tearing modulus is reasonably conservative.

c) Describethemethodofvalidating(benchmarking)eachcomputer code used in the leak rate and fracture mechanics calculations.

5. Leak Rate Analysis Describe the computational procedure used to calculate crack opening area.

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6. Fatigue Crack Growth Analysis a) The data cited in Reference 8-2 as the basis for the fatigue crack growth rate should be included in the report in graphical fom that would illustrate and justify the fatigue crack growth

i ,*

, t rate constants in equation 8-4 of WCAP 10537. These equations should represent the fatique crack growth rate of the material characterized in item 1.

b) The applicant will perforin as realistic analysis as possible using service level A and B loads. The aspect ratio for the postulated crack in the fatigue evaluation shou'Id be 6. The ,

aspect ratio should remain constant throughout the analysis.

Unless otherwise justified the maximum allowable flaw depth is j the smaller of:

l (1)60%ofthewallthickness,or (2) the depth at which the plastic zone is equal to the remaining

ligament.

1 c) The length of the fatique crack must be less than both:

(1) thelengthoftheinstabilitythru-wallcrackat/T(N+SSE) and (2) 1/2(instabilitythru-wallflawatN+SSE) i The applicant is requested to confirin that the fatigue analysis includes theitemslistedinb)andc),above.

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