ML20246K365
| ML20246K365 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 07/13/1989 |
| From: | Creel G BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8907180151 | |
| Download: ML20246K365 (8) | |
Text
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BALTIMO RE GAS AND ELECTRIC CHARLES CENTER P.O. BOX 1475 BALTIMORE, MARYLAND 21203 GEORGE C. CREEL vict Passiocut fivettam EwEnov (3o0 aso-ames July 13,1989 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Document Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Pronosal of Alternative to ASME Code Section III Requirements I
REFERENCES:
(a) NRC Staff Guidance Letter on ASME Relief Requests dated January 1978 l'
(b) Steam Generator Tube Plug Integrity Summary Report, April 1989, Westinghouse Electric Corporation, WCAP-12244, Revision 1 (c) Stress Corrosion Cracking Resistance of Alloys 600 and 690 and compatible Weld Metals in BWRs, July 1988, Electric Power Research Institute, NP-5882M Final Report (d) Stress Corrosion of Alloys 600 and 690 in Acidic Sulfate Solutions at Elevated Temperatures, October 1983, Electric Power Research Institute, NP-3043 Final R.eport (e) Cases of ASME Boiler and Pressure Vessel Code, Case N-20-3, November 30,1988 (attached)
Gentlemen:
In accordance with 10 CFR 50.55a(a)(3), we are proposing an alternative to the requirements of 10 CFR 50.55a(c). This proposal is submitted in accordance with Referer.ce (a).
We have determined that Alloy 690 is superior to Alloy 600 for use as replacernent pressurizer penetration material due to its primary water stress corrosion cracking resistance. The ASME Code approves the use of Alloy 690 under Specification SB-163 for Section 111 (Code Case N-20-3 attached), but Specification SB-166 or SB-167 is not currently included. We are proposing to use, at our option, Alloy 690 meeting Specification SB-166 or SB-167 instead of Alloy 600 for pressurizer penetration replacements.
Ao'l9 8907180151 890713 PDR ADOCK 0500031,7
,I p
Document Control Desk July 13,_1989 Page '2 1.
Components to Which an Alternative is Proposed The attached drawing identifies all pressurizer penetrations. We plan to use Alloy 690 under Specification SB-166 or SB-167 for any penetration that requires replacement. These penetrations were originally designed to ASME Code Section ill, Class 1,1965 Edition through Winter 1967 Addenda.
11.
ASME Requirement to Which an Alternative is Pronosed We have adopted the alternative allowed by ASME Code Section XI,1983 Edition with Addenda through Summer 1983, paragraph IWA-7210(c). The alternative allows that " replacements may meet all or portions of the requirements of later editions of the Construction Code... " We have reviewed the ASME Code Section til and noted that the use of Alloy 690 meeting Specifications SB-166 and SB-167 is not included. Regulatory Guide 1.85 lins Code Case N-20-1 as approved; however, this case applies only to Specification SB-163. Addition-ally, we note that Code Case N-20-1 has expired and has been renewed as N-20-3.
111.
Basis for Proposine an Alternative During the current Unit 2 refueling outage, an inservice inspection of the Unit 2 pressurizer discovered evidence of reactor coolant leakage from a number of heater penetrations and one pressurizer pressure / level penetration.
Subsequent investigation is expected to reveal that a number of these I
penetrations must be either repaired or replaced.
The original penetrations are made of Alloy 600. While this material is acceptable as replacement material, it does not have the superior stress corrosion cracking resistance of Alloy 690. The increased chromium content of Alloy 690 produces a material that has been demor strated to be immune or resistant to degradation mechanisms that are active with Alloy 600. For example, on page 2-9, Reference (b) states, "all available data for Alloy 690 suggests this material
(' microstructure') is not susceptible to primary water stress corrosion cracking (PWSCC). Therefore, ever though the other factors are present (stress and temperature), PWSCC has not been observed in this alloy." Page 8-1 of Reference (c) concludes, " Alloy 690 was immune to SCC in pure water under all conditions evaluated" and " Ranking of the alloys in terms of their SCC resistance in the simulated resin intrusion environment indicated that
. Alloy 600... had intermediate resistance, and Alloy 690 had the highest resistance." Page v of Reference (d) states, " Alloy 690 was much more resistant to stress corrosion than Alloy 600 and was immune to i
cracking in most of the acidic sulfate solutions examined."
l Based on the superior stress corrosion cracking resistance properties of i
Alloy 690, we prefer to use it as the replacement material for our pressurizer penetrations. The ASME Code Section 111 allows use of Alloy 690 under Specification SB-163: Seamless Nickel and Nickel Alloy Condenser and IIcat Exchanger Tubes (up to 7/8-inch OD) per ASME Code Case N-20-3 (Reference c). The ASME Code, however, does not include use of Specification
Document Control Desk -
July 13,1989 Page 3 SB-166: Nickel-Chromium-Iron Alloy Rod, Bar and Wire or Specification SB-167:
Nickel-Chromium-Iron Alloys Seamless Pipe and Tube (up to 6-5/8 inches OD).
Use of Specifications SB-166 and SB-167 will allow us to replace the pressurizer penetrations with Alloy 690.
IV.
Additional Requirements Through this proposal, we assure you that we will meet the applicable additional requirements imposed on Specification SB-163 in the ASME Code Case N-20-3 when we use Specification SB-166 or SB-167. Specifically, we will establish the separate welding procedures and performance qualifications required for Alloy 690 by the Code Case.
Your approval of this proposal is requested by August 26 1989, to allow the use of Alloy 690. Use of this material will provide an acceptable level of quality and safety as described in paragraph III above and References (b), (c) and (d). The need for this request could not reasonably have been anticipated since the apparent failure of the pressurizer penetrations is a rare occurrence. Compliance with the specified require-ments of ASME Code Section Ill will not result in hardship or unusual difficulty in affecting repairs. Ilowever, the use of Alloy 600 may be related to the root cause of the apparent failure of the pressurizer penetrations. Therefore, we prefer to use Alloy 690 and avert the hardship of not using a superior material.
Should you have any further questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours
&l GCC/JMO/ dim
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cc:
D. A. Brune, Esquire J. E.
Silberg, Esquire R. A.Capra, NRC S. A.McNeil,NRC W. T. Russell, NRC IL Eichenholz/V. L. Pritchett, NRC T. Magette, DNR i
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CASE N-20-3 CASES OF ASME BOILER AND l'RESSURE VLSSEL CODE Approval Date: November 30,1988, 3ee Numericindex for emiration and any reaffirmation detr*
Case N 20 3 mium Alloy 800 seamless condenser and heat exchanger
$8163 NickelChromium-Iron Tubing (Alloys 600 and tubing meeting the requirements given on the Inquiry 690) and Nickel.f ron Chromium Alloy 800 at a Specified may be used in the construction of Class I components
(
Minimum Yield Strength of 40.0 kai and Cold Worked in accordance with Section III, Division 1, provided the Alloy 800 at a Yield Strength of 47.0 ksi tensile, yield strength, and design stressintensity values Section 111, Division 1, Class 1 as listed in Tables 1,2, and 4, respectively are used. In Inquiry: May nickel. chromium. iron and nickel-iron-addition to the marking requirements of SB-163, the chromium alloy seamless condenser and heat exchanger tubing shall be identified with this Case number. For tubing meeting the size
- range and specified properties as extemal pressure the required thickness of the tubing listed in Table 1 and otherwise meeting the requirements shah be determined-in accordance with Par. NB.3133 of SB.163 for Alloy 600 and 800 and the requirementsof using Fig I for Alloys 600 and 690 and using Fig. 2 for SB 163 for Alloy 690 except for thechemistry (Alloy 690 Alloy 800. Welding procedure and performance qualifica-chemistry is listed in Table 3), he used in the construction.
ti na shall be in acc rdance with Section IX. Separate
_ elding pmcedure and perfonnance cualificatmns are w
of Class I components in accordance with Section III, Division It required for Alloy 690.Weldingof CW Alloy 800 material shall be limited to tube.to-tube sheet welds.
Reply: It is the opinion of the Committee that nickel-chromium-iron Alloys 600 and'690 and nickel-iron chro-s e
TABLE 1 Specified Mechanical Properties and Size Ranges Min. Spec.
Spec. Yield Strength Min.
Tube Size Range,in.
Tensile ksi (0.2% Offset)
Elongation Wall Strength, ksi Min.
Max.
2 in., %
0.D.
Thickness Alloys 600 and 690 80 40 65 30 84 to'4 Up to 0.100 Alloy 800 80 40 65 30 84 to '4 Up to 0.100 CW Alloy 800 83 47 70 30 84 to '4 Up to 0300 TABLE 2 Design Stress intensity Values,Sm, ksi, for Material Temperature Not Exceeding. *F 10b' 200 300 400 SVO 600 650 700 750 800 Alloys 600 and 690 26.6 26.6 26.6 26f.
26.6 26.6 26.6 26.6 26.6 26 6 Alloy 800 26.6 26.6 26.6 26.0 25.7 25.7 25.7 25.7 25.7 25.7 CW Alloy 800 27.8 27.8 27,.8 27.5 26.9 26.6 26.6 13 SUPP,11 - NC
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CASE (continued)
N-20-3,
g CASES OF ASME BOILEll AND PitESSUltE VESdr,1, CODE TABLE 3 1
~ Chemistry - Alloy 690 l
- I r*ercent Min.
Max.
Cr 27 31 Fe 7
11 C
0.05
(
Si 0.50 h
Mn 0.50 S
0.015 Co 0.10 Cu 0.50 Ni 58.0
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TABLE 4 Yield Strength Values - Alloys 600,690 and 800 Y. S. Value CW Temp., *F Alloys 600 & 690 Alloy 800 Allo / 800 100 40.0 40.0 47.0 200 38.2 36.8 42.5 300 37.3 34.6 10.6 400 36 3 33.0 39.2 500 35.7 31.8 38.5 600 353 31.1 37.7 650 35.2 30.9 37.3
~
700 35.0 30.6 750 34.9 30.3
_t 00 34.8 30.0 9
a O
IUPP.11 - NC
4 CASE (continued)
N-20-3 CASES OF ASME BOILER AND PRESSURE VESSEL CODE l
l l
40.000 35.000 30.000 25.000
/up to 100 F
' l 1 ll 7 "* F 20 M 18.000 g
/
s s
I i 16'000 d%b.
M to 00D F
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j e
y 14.000 m
f 7
10.000 Dj
- ))'/
8,000 y,
7,000 r
E a 31.6 x 108 6.000 7
E
- 30.0 m 10e yjj E.
- 26.6 m, tos_
q77 6m lli l I #f' y
4m 2
3 4 6 6789 2
3 4 66789 2
3 4 66789 2
3 4 66789
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.0001
.001
.01
.1 FACTOR A 4
FIG.1 CHART FOR DETERMINING SHELL THICKNESS OF CYLINDRICAL AND SPHERICAL VESSELS UNDER EXTERNAL PRESSURE NickelChromium-tron Alloys 600 and 890 SB 163, S min = 40#00 psi y
20.000 18.000 100 F ---- 16.000 MM 4 g 600 F.
12.000 I --
000 F ---
10.000
/4-7_,, "'
N 1,100 p p-9.600
/% /~/-
8.000 e
IE h
,rff 6.000
////
/h!
o HH 4.000 E
- 28 6 a 10 N 6
3.500 E
- 26.6 m 106g 8
E
- 24.8 a 10 ~
3 000 r
E
- 23.0 m los 2.500 l
2.000 2
3 4 6 6789 2
3 4 66789 2
3 4 56789 2
3 4 66789
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.1 F ACTOR A FIG.2 CHART FOR DETERMINING SHELL THICKNESS OF CYLINDRICAL AND SPHERICAL VESSELS UNDER EXTERNAL PRESSURE WHEN CONSTRUCTED OF NICKEL IRONCHROMlUM ALLOY 800(ANNEALED) 15 SUPP.11 - NC
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CASE (continued)-
N-20-3.
]
CASES OF ASME BOILER AND PRESSURE VESSEL CODE TABLE 5 TUBULAR VALUES FOR FIG. 3 Temp., *F A
8 Temp., 'F A
B,
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psi psi 100 0.n8-03 10,000 500 0.75-03 10,000 0.48-03 14,100 0.10-02 13,800 0.40-02 18,400 0.20-02 14,400 O.10-01 21,000 0.40-02 15,500 0.20-01 22,400 0.10-01 17,100 0.30-01 23.000 0.20-01 17,400 0.25-01 17,700 300 0.75-03 10,000 700 0.78-03 10,000 0.11-02 14,300 0.10-02 12,300
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0.20 02 14,800 0.20-02 13,200 0.40-02 16,300 0.40-12 14,300 0.10-01 18,200 0.10-01 15,900 O.20-01 19.500 0.20-01 17,200 0.30-01 20,100 0.30-01 18,000 50.000 40,000 35,000 30.000 25,000
- y to 100 F
-/,-_
300 F 20,000
=
f G
GJV E = 29.6 a 10.,,,
/h%Nh h
6
- =
N 500 F 7
14,000
,,,,.,go p t 2,000 E = 26.6 a 1
-N 10,000 g
9,000 6
8,000 Ea25.5a10 _ ff is 6,000 5.00u 2
3 4 56789 2
3 4 5 6789 2
3 4 56789 2
3 4 56789 0.00001 0.0001 0 001 0.01 0.1 FACTOR A FIG.3 CHARf FOR DETERMINING SHELL THICKNESS OF CYLINDRICAL AND SPHERICAL VESSELS UNDER EXTERNAL PRESSURE WHEN CONSTRUCTED OF NICKEL-IRON-CHROMlUM ALLOY 800 (MODIFIED)
SUPP,11 - NC
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