ML20053E345

Responds to Questions NRC Raised During 811123 Independent Verification Program.Corrective Actions:Weld LP-K-114 Ground & Liquid Penetration Inspected

ML20053E345
Person / Time
Site:	Zimmer
Issue date:	12/22/1981
From:	Sager H CINCINNATI GAS & ELECTRIC CO.
To:	Danielson NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20053E316	List: ML20053E321 ML20053E336 ML20053E345
References
QA-1558, NUDOCS 8206070815
Download: ML20053E345 (8)

Text

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~. , i hf 'I 4-g3y L TIIIC CINCINN A'I'I GAS & ICI ICCTItIC C() Nil" Y M b- b ZIMMER NUCLEAR STATION - P.O. BOX $01, MOSCOW, 01110 M3 cmenwri omo 4 020e December 22, 1981 QA-1558 U. S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 At tent ion : Mr. Danielson RE: WM. H. ZIMMER NUCLEAR POWER STATION - UNIT I RESPONSE TO NRC ACTION ITEMS - W.O. #57300 JOB E-5590 FILE NO. NRC-2 Centlemen:

The purpose of this letter is to respond to some questions raised during the NRC independent verification program.

1. Liquid Penetrant Indication in Lug Weld LP-K-114 Of forty-two (42) welds examined by the NRC, weld LP-K-114 was identified as containing a rejectable linear indication. This weld is on Lug -LP-011-HV.

This indication was also detected during the normal course of pre-service inspection on 1-9-80. CG6E NR E-7546 and HJK NR E-3264 were issued to document this discrepancy. The weld has been ground and liquid penetrant inspected. This inspection showed that the indication was a result of inadequate surface preparation. The weld is now acceptable and no further investigation is required.

2. Minimum Wall Thickness Welds HP-12A and LP-4 were both identified by the NRC as violating the minimum wall requirements using the mil tolerance requirement of 12.5%

of nominal. The actual S&L design minimum wall is based upon a formula contained in S&L specification H-2256. This formula is repeated below:

Tm = PDo

+A 2 (S + YP) 8206070815 820602 M 14 E PDR ADOCK 05000358 PDR G

.. o Mr.- Danielson

.U. S. Nuclear Regulatory Commission Region III December 22, 1981 QA-1558 Page 2 Where Tm = minimum wall thickness (inches)

P = Design Pressure (PSI)

Do = Diameter of Pipe (OD inches)

S.= Allowable stress intensities taken from the stress tables contained in ANSI B31.1. -

Y = 0.4 (Constant from ASME)

A = corrosion / erosion allo' , ace

.065 for SS

.125 for CS Using this equation, the minimum wall requirement for HP-12A and LP-4 is .699" and .558" respectfully. The measured wall ' thickness of HP-12A is acceptable, -however, the thickness of LP-4 is below the minimum .re-quirements. NR C-QAD-81-241-E has been issued to document this violation.

The disposition of this NR is " accept as is" on the basis that the wall thickness of LP-4 is still above the minimum -requirements of _ ASME Section III which uses more liberal stress intensities than ANSI B31.1.

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See attachment 1 for computations.

It should be pointed out that the weld identified by the NRC as HP-12A is actually HP-12.

3. Pipe Mismatch Five (5) welds were identified by the NRC as containing severe mismatch. Two i (2) of these welds (FC-100 and HP-6A) were removed earlier for analysis. The remaining three (3) welds (LP-29B, LP-SW53, LP-30) have been inspected ultrasonically to produce a cross section profile in'four (4) quadrants of each weld. These profiles do not indicate mismatch. They ldo however, show counterbores and root concavity which may have been interpreted as . mismatch'

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on the radiographs.

Copies of these profiles are attached for your information.

Other questions raised by the NRC are under investigation by CG&E. We will -

! ' respond to these questions as information becomes available.

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Mr. Danielson

.U, S. Nuclear Regulatory Commission Region 7.11 December 22, 1981 QA-1558 Page 3 Should you have any question regarding these responses, please do not hesitate to call.

Very truly yours, THE CINCINNATI GAS & ELECTRIC COMPANY By II. R. SAGE MANAGER, QUALITY ASSURANCE REA:ac Attachment cc: NRC Resident Inspector Attn: W. F. Christainson

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ATTACHNENT 1 Minimum wall calculations for weld HP-12 using the equation Tm = PDn +A 2 (S+ YP)

From the piping Line List the following information is obtained:

Design Pressure (P) = 1400 PSIG Design Temperature = 2120F Piping design table a 607 WZ The piping design table dictates the material specification (ASTM A106 Grade- B)-

which is necessary information to obtain the allowable stresses from ANSI B31.1.

The outside diameter of the pipe (Do) is obtained from any commercial pipe manual. HP-12 is 12.75" OD.

The allowable stress (S), from ANSI B31.1, for ASTM A106 Grade B with temperature

. lcss than 650 0F is 15000 PSI.

The valve of (T), which is taken from ASNE,Section III, Table NC-3641.1(a)-2, -

is 0.4 for both ferritic and austenitic steels if design temperature is 9000F or less.

(A) is a corrosion /errosien allowance contained in S&L specification H-2256.

The valves of (A) are .065" for SS and .125" for CS.

With this information, the equation can now be solved as follows:

Tm = (1400)(12.75) 2 [35000 + (0.4)(1406) + .125 Tm = 17850 + .125 31120 Tm = 0.699" 0.699 is less than the measured thickness of .728 therefore HP-12 is acceptable.

Using the same sources for information regarding LP-4, the obtained valves are as follows:

P = 1250 PSI D,o = 10. 7 5" S = 15000 PSI Y = 0.4 l A = .125" 4

The solution is:

I Tm = (1250)(10.75) i 2 [:15000 + (.4)(1250) + .125 l

l Tm = 13437 + .125 l

31000 l

l

Attachment 1 (cont'd)

Page 2 Tm = .558" The measured thickness of LP-4 is .509" which is less than the design minimum wall of .558" therefore the weld is unacceptable to the requirements of S&L specification H-2256. The allowable stress from ASME Section~'III is 17300 PSI compared with the more conservative 15000 PSI from B31.1. Using 17300 PSI stress intensity, the' actual minimum wall computes to be .502" which is below the measured thickness of .509, therefore the weld is acceptable to Section

-III requirements.

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