ML19225C855
| ML19225C855 | |
| Person / Time | |
|---|---|
| Site: | Hatch, Vogtle  |
| Issue date: | 07/18/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | John Miller GEORGIA POWER CO. |
| References | |
| NUDOCS 7908030013 | |
| Download: ML19225C855 (2) | |
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101 MARIE TT A ST. N., SUIT E 3100 Y88
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..s JUL 181979 In Reply Refer To:
RII:JPO 50-321, 50-366 50-424, 50-425 Georgia Power Company Attn:
J. H. Miller, Jr.
Executive Vice President 270 Peachtree Street, N. W.
Atlanta, Georgia 30303 Centlemen:
The attached enclosure, Circular 76-06, was inadvertently omitted in the July 17, 1979 issue of Information Notice 79-19.
Sincerely, w)
,byt James P. O'Reilly Director
Enclosure:
Circular 76-06 440 14(
'79080300 6
JUL 181979 4
Georgia Power Company
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M. Manry, Plant Manager Post Office Box 442 Baxley, Georgia 31513 C. E. Belflower Site QA Supervisor Post Office Box 442 Baxley, Georgia 31513 K. M. Gillespie Construction Project Msnager Post Office Box 282 Waynesboro, Georgia 30830 E. D. Groover QA Site Supervisor Post Office Box 282 Waynesboro, Georgia 30830 5/
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[9JUl.N p}. 31 November 26, 1976 IE Circular No. 76-06 STFISS CORPOSION CRACKS IN STAGNANT, LOW PRESSURE STAINLESS PIPING CONTAINING BORIC ACID SOLUTION AT PWR's DESCRIPTION OF CIRClHSTANCES:
During the period November 7, 1974 to November 1, 1975, several incidents of through-wall cracking have necurred in the 10-inch, schedule 10 type 304 stain 2cus steel piping of the Reactor Building Spray and Decay Heat
'Remova) Systen:n at Arkans.as Nuc1 car PJ ant No.1.
On October 7, 1976, Virginia Electric and Power also reported through-wall cracking in the 10-inch sche.dule 40 type 304 stainless diccharge piping of the "A" recirculation spray heat exchanger at Surry Unit No. 2.
A recent inspection of Unit 1 Containnent Recirculation Spray Piping revealed cracking similar to Unit 2.
On October 8, 1976, another incident of similar cracking in 8-inch schedule 10 type 304 stainless piping of the Sefety Injection Pump Suction I.irje at the Cinna facility was reported by the licensee.
Information received on the r.etallurgical analysis conducted to date indicates that the failures were the result of intergranula. stress corrosion cracking that initint.ed on the inside of the pip!.ng.
A comonality of f actorn observed associated with the corresion taechanism were:
1.
ne cracks were adjacent to and propagated along weld zones of the thin-valled low pressure piping, not part of the reactor coolant system.
2.
Cracking occurred in piping containing relatively stagnant boric acid solution not required for normal operating conditions.
3.
Analysis of surface producta at this time indicate a chloride ion interaction with oxide formation in the relativaly stagnant boric acid solution as the probable corrodant, with the state of stress probably due to velding and/or fcbrication.
he source of the chloride ion is not d,2 finitely known.
However,.at ANO-1 the chlorides and sulfide level observed in the surface tarnish film near velds is believed to have been introduced into the piping during centing of the sodium thinsulf ate discharge va3ves, or valve leakage.
Eissilarly, at Cinns the chlorides and potential oxygen 440 pgs lf B BfM Q%b kNlm DY
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November 26, 1976 IE Circular No.
availability were assumed to have been present since original conscruction of the borated water storage tank which is vented to atmosphere.
Corrosion attack at Surry is attributed to in-leakage of chlorides through recirculation spray heat exchange tubing, allowing
. buildup of contaminotcd water in an otherwise normally dry spray piping.
ACTION TO BE TAKIN BY LICENSEE:
1.
Provide a description of your prcgram for assuring continued integrity of those safety-related piping systems vhich are not This frcquently flushed, or which contain uenflowing liquids.
program r.houlc include considerution of hydrostatic testing in accordance w1:.a ASMF. Code Section X1 rules (1974 Edition) for all active systecc required for safety injection and contain=ent spray, including their recirculation modes, from source of water supply up to the second isolation valve of the primary system.
Similar tests should be considered for other safety-related piping systems.
2.
Your program should also consider voluraetric exacination of a representattve number of circ.ueferential pipe welds by non-destructive examination techniques.
Such examinations should be perforned generally in accordance with Appendix 1 of Section XI of the ASME Code, except that the examined area should cover a distance of approximately six (6) times the pipe wall thickness (but not 3 css than 2 inches and need not exceed 8 inches) on each side of the weld.
Supplementary exaraination techniques, such as radiography, should be used where necessary for evaluation or confirmation of ultrasonic indications resulting from such cxamination.
3.
A report describing your program and schedule for these inspec-tions should he submitted within 30 days after receipt of this Circular.
4.
The NRC Regional of fice should be informed within"24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, of any adverne findings resulting during nondestructive evaluation of the acces.ible piping welds identified above.
5.
A sumaty report of the examinations and evaluation raf results should be submitted within 60 dsys from the date of completion of proposed testing and examinations.
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/ 9 J U L 17 f-) 13 I Novec.ber 26, 1976 IE Circular No. 76-06 should also include a brief dencription of This su==ary report plant conditions, operating procedures or other activfties which provide assurance that the ef fluent chemistry will maintain Iow levels of potential corrodants in such relatively stagnant regions within tho yiping.
Your responses should be nubmitted to the Director of this of fice, Division with a copy to the NRC Of fice of Inspection and Enforcement.
of Reactor Inspection Programs, Waahington, D.C.
205S5.
i Approval of HRC requirements for reports concerning possible generic
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problems has been obtained under 44 U.S.C 3152 f rom the U.S. General Accounting Office.
(CAO Approval B-380255 (R0f/62), expires 7/31/77.)
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