ML20033H097

Approves Use of Alloy 690 as Alternate Replacement Matl for Pressurizer Heater Penetrations,Per ASME Code & 10CFR50.55a(a)(3).Request Necessitated by Reactor Coolant Leakage from 20 Heater Penetrations in Unit 2 Pressurizer

ML20033H097
Person / Time
Site:	Calvert Cliffs
Issue date:	04/05/1990
From:	Capra R Office of Nuclear Reactor Regulation
To:	Creel G BALTIMORE GAS & ELECTRIC CO.
References
TAC-73816, TAC-73817, NUDOCS 9004180161
Download: ML20033H097 (5)

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. UNITED STATES 4

NUCLEAR REGULATORY COMMISSION

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WASHINGTON, D. C. 2055$ ;

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April 5 -1%G

-Docket Hos. 50-317 and 50-318

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Mr. G. C. Creel Vice President Nuclear Energy

~ Baltimore' Gas'& Electric Company Calvert Cliffs Nuclear Power Plant-z!

MD Rts'2 & 4 d

P.O. Box >1535 j

Lusby, Maryland - 20667 1

1

SUBJECT:

APPROVAL OF ASME CODE USE 0F ALTERNATE MATERIALS FOR PRESSURIZER-PEHETRATIONS -

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REFERENCE:

-TACNumbers73816-(Unit'1)and-73817-(Unit 2)

The NRC staff has completed its review of your request dated July 13, 1989,~as amended by(3) as anLalternative-to that specified by?the ASME-Code for

-letter dated October 27, 1989'. to'use a material under 10 CFR h

50.55a(a)

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. penetrations.

This request was necessitated'by your discovery of reactor:

coolant leakage from 20 theater penetrations and one pressure / level penetration in-the Calvert Cliffs Unit 2-pressurizer and~the need to replace the instrument nozzels.

Subsequently, your September 20,.1989, report identified the=cause of i

the leaks in=the pressurizer heater sleeves.Las primary water stress corrosion cracking (PWSCC).

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Currently, the Units 1 and 2 pressurizer 1 penetrations are fabricated from Alloy 600 which is susceptible to PWSCC. You-have proposed using Alloy 690 for the replacement of Unit 1 and 2 pressurizer penetrations as an alternate:to.the continued use of Alloy 600 under Specifications SB-166, " Nickel-Chromium-Iron-Alloy Rod,' Bar and Wire" and SB-167, " Nickel-Chromium-Iron Alloy Seamless Pipe

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and Tube (up to 6-5/8 inches 0D)," of the 1983 Edition of.Section III of-the ASME Boi',er and Pressure Vessel Code.

'l Your request indicated that the alternative use of Alloy ~690 is preferred as it a

has mechanical properties (e.g.

tensile strength, yield strength range, and-t design stress intensity values), equivalent to those of Alloy 600, but is generally less susceptible to PWSCC than is Alloy-600.

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The NRC staff agrees that Alloy 690 has been demonstrated to be superior to I

Alloy 600 in resisting PW5CC though this resistance varies with thermal treatment. Consequently, the use of Alloy 690 'as a replacement material is generally considered as a move towards-improved PWSCC resistance, q

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l Mr.- G. C. Creel

- 2L-April 5, 1990 Alloy 690 is currently permitted by ASME Code Case N-20-3, which was adopted

in NRC Regulatory Guide 1.85, to be used as a replacement for Alloy 600, This is allowed under specification SB-163, " Seamless Nickel and Nickel Alloy s

Condenser and Heat Exchange Tubes _(up to 7/8 inch 00)," when separate Alloy 690 welding procedures and performance cualifications are established. ASME= Code Case N-474, recently approved by the ASME Code Committee, applies only to specification SB-163 and allows the use'of 35 Ksi minimum yield strength material.

You have comitted to meet the applicable; additional' requirements'of Code Cases N-474 and N-20-3 and to establish welding procedures and performance-qualifications required by.ASME Code Case N-20-3 for Alloy 690.

i The staff has concluded that: 1)' Alloy 690 has tensile and ield strengths equivalent to A11oy 600; 2) is less susceptible to PWSCC; 3 the applicable additional requirements of Code Cases N-474 and N-20-3 will be met; and 4) welding procedures and performance qualifications required'by thefASME Code-T Case for Alloy 690 for. pressurizer penetrations and procurement of material in accordance with the specifications and Code Cases discussed, a level-of quality.

and safety equivalent to that provided-by the use of'the ASME. Code approved:

Alloy 600 material will be maintained.

Consequently, your July 13,:1989 request, as amended on '0ctober 27 1989, to use Alloy 690 as an alternate replacement material for pressurizer heater penetrations is approved, in accordance with the provisions 10 CFR 50.55a(a)(3), as the use of Alloy 690 in this capacity provides an acceptable level of quality and safety. However,'we request that you provide the results of the failure analysis being performed on the instrument nozzels-upon'.its completion.

This completes the staff's action in relation to the above referenced TAC numbers.

Sincerely, W_

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-$nRobertA.Capra, Director Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation cc: See next page 5

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Mr. G.-C.' Creel

~. Baltimore-Gas & Electric.Companf

- Falvert Cliffs Nuclear Power Plant.'~

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Mr. Willit.m T. Powen, President-Mr. Joseph H.: Walter k

Calvert County Board of Engineering Division Corrissioners Prince. Frederick, Marylands 20678

.Public Service Commission of' Maryland

'American Building 101 E. Baltimore Street'

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D. A.: Brune, Esq. :

Baltimore, Maryland -21202-3486-l General Counsel

. Baltimore Gas and. Electric. Company Ms. Kirsten A. Burger, Esq.

P. 0. Box 147f

' Maryland People's Counsel-Baltimore, Maryland 31203 American Building, 9th Floor 1

231 E. Baltimore Street-Mr. Jay E. Silberg, Esq..

Baltimore, Maryland 21202 Shaw, Pittman,-Potts-and Trowbridge j

2300 N. Street, NW Ns.. Patricia Birnie iWashington, DC' 20037 i

Co-Director Maryland Safe Energy Coalition

.f Mr. W. J. Lippold, General-Supervisor

'P. O. Rox 90?

Technical Services Ergineering Calvert Cliffs Nuclear Power Plant Columbia, Maryland. ^1044 j

i MD Rts 2 ?. a, P. O. Box 1535 Lusby, Maryland 20657' o

Resident Inspector c/c U.S. Nuclear Regulatory Commissien P. C. Box 437 Lusby, Maryland 20657 1

i Mr. Thomas Magette Administrator - Nuclear Evaluations I

Department of Natural Resources 1

580: Taylor Avenue Tawes State Office Building PPER P3-Annapolis, Maryland 21401 l

Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, Pennsylvania 19406 i

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' Mr. _ G. C. Creel 2-April 5, 1990 Alloy 690-is currently permitted by ASME Code Case N-20-3,'which was adopted.

in NRC Regulatory Guide 1.85, to be used as a replacement for Alloy 600.

This is allowed under specification SB-163, " Seamless Nickel and Nickel Alloy Condenser and Heat Exchange Tubes (up to 7/8 inch OD)," when separate Alloy 690 welding procedures and performance qualifications are established. ASME Code Case. H-474, recently approved by the ASME Code Comittee, applies only to -

specification SB-163 and allows the use of 35 Ksi minimum yield strength material.

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You have committed to meet the. applicable additional requirements of Code l

Cases N-474 and N-20-3 and to establish welding procedures and performance.

qualifications required by ASME Code Case N-20-3 for Alioy 690.

The staff has concluded that: 1) Alloy 690 has.tensil and yield strengths equivalent to Alloy 600; 2) is less susceptible to PWSCC; 3) the applicable:

additional requirements of Code Cases-N-474 and N-20-3 will be met;_and 4) welding procedures and performance qualifications required by the ASME_ Code Case for Alloy 690.for pressurizer penetrations and procurement:of material in i

accordance with the specifications and Code Cases discussed, a level of quality and safety equivalent to that provided by the use.of-the ASME Code approved A11ny 600 material will be maintained.

Consequently 'your July 13, 1989 request, as amended on October 27, 1989, to use Alloy 690 as an alternate replacement material.for pressurizer heater penetrations is approved, in accordance with the provisions 10 CFR 50.55a(a)(3), as.the use of Alloy 690 in this capacity provides an acceptable-level of quality and safety. However, we-request that you provide the results of the failure analysis being performed on the. instrument nozzels upon its completion.

This completes the staff's action in relation to the above referenced TAC..

numbers.

Sincerely,-

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/s/

Robert A. Capra, Director Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation cc: See next page

. Distribution:

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' DOCUMENT NAME: TAC 73816/73817

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-Mr.- G..C'. Creel A a m.:

'i A11oy'690 is currently' permitted by ASME Code Case N-20-3, which'was adopted in NRC Regulatory Guide 1.85, to be used as a replacement for-Alloy 600.

Thisjis allowed under specification SB-163, Seamless Nickel' and Nickel Alloy

. Condenser and Heat Exchange Tubes (up to 7/8 inch OD)," when separate Alloy 690.

D ' welding procedures and performance qualifications are established. ASME Code

"CaserN-474', recently approved by the ASME Code Committee, applies.only to 7

spuffication SB-163 and allows the use of 35.Ksi minimum" yield strength L

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You have connitted to meet the applicable. additional requirements of Code f'1 j

Cases N-47.4 and N-20-3 and to establish welding procedures and performance'-

qualifications required by ASME Code Case N-20-3 for Alloy 690.

'The staff has concluded that: 1) Alloy 690 has ph to A.11oy 600; 2) is= less susceptible to PWSCC; 3)ysical properties equivalent the applicable additional-requirements of Code Cases H-474 and N-20-3 will be met; and 4)' welding 1

procedures-and-performance' qualifications required by the ASME Code Case for i

~

Alloy 690 for pressurizer penetrations and procurement of material.in accordance with.the specifications and Code Cases discussed, a level of.

quality and safety equivalent to'that provided by the use of the ASME Code approved Alloy 600 material will be maintained.

Consequently, your July. 13, 1989 request, as amended on October 27', 1989, to use Alloy 690 as an alternate replacement material for pressurizer heater 1

penetrations is approved, in accordance with the-provisions 10 CFR 50.55a(a)(3), as the -use of. Alloy 690 in this capacity;provides an acceptable-1 level of quality and safety.

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This completes the staff's action in relation to-the above referenced TAC numbers.

Sincerely, Robert A. Capra, Director Project Directorate I-1 Division of Reactor. Projects - I/II Office of. Nuclear Reactor Regulation ec: See next page 1

D_ i_stribution:

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NRC/ Local PDRs EJordan TMurley/JSniezek OGC o,. lCRossi ACRS(10)

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