ML19254F079
| ML19254F079 | |
| Person / Time | |
|---|---|
| Site: | 05000580, 05000581 |
| Issue date: | 10/29/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Mcwhorter R OHIO EDISON CO. |
| References | |
| NUDOCS 7911060135 | |
| Download: ML19254F079 (1) | |
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UNITED STsTES l'
j NUCLEAR REGULATORY COMMISSION 7
- c-c REGION til o, f f
799 ROOSEVELT ROAD
%f v*....f cLEN ELLYN. ILLINOIS 60137 OCI k, p,
Docket No. 50-580 Docket No. 50-581 The Ohio Edison Company s
ATTN:
Mr. R. J. McWhorter Vice President Engineering 76 South Main Street Akron, OH 44308 Gentlemen:
The enclosed IE Bulletin No. 79-17, Revision 1 is forwarded to you for information. No written response is required. However, the potential corro-sion behavior of safety related systems as it regards your plant over the long term should be taken into consideration.
If you desire additional information concerning this matter, please contact this office.
Sincerely, Y^g ^ bs=
James G. Keppier Director
Enclosure:
IE Bulletin No. 79-17, Revision 1 cc w/ encl:
Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Harold W. Kohn, Power Siting Commission 1291 149 9911000136
UNITED STATES SSIM< No.
6820 NUCLEAR REGULATORY COMMISSION Accession No.
0FFICE OF INSPECTION AND ENFORCEMENT 79082201$7 WASHINGTON, D.C.
20555
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October 29, 1979 IE Bulletin No. 79-17 Revision 1 c'
PIPE CRACKS IN STAGNANT B0 RATED WATER SYSTEMS AT PWR PLANTS Description of Circumstances:
IE Bulletin No. 79-17, issued July 26, 1979, provided information on the cracking R1 experiencec to date in safety-related stainless steel piping systems at PWR R1 plants.
Certain actions were required of all PWR facilities with an operating R1 license within a specified 90-day time frame.
R1 After seseral discussions with licensee owner group representatives and inspection R1 agencies it has been determined that the requirements of item 2, particularly R1 the ultrasonic examination, tray be impractical because of unavailability of R1 qualified personnel in certain cases tc complete the inspections within the time R1 specified by the Bulletin.
To alleviate this situation and allow licensees the R1 resources of improved ultrasonic inspection capabilities, a time extension and R1 clarifications to the bulletin have been made.
These are referenced to the R1 affected items of the original bulletin.
R1 During the period of November 1974 to February 1977 a number of cracking incidents have been experienced in safety-related stainless steel piping systems and por-tions of systems which contain oxygenated, stagnant or essentially stagnant bor-ated water.
Metallurgical investigations revealed these cracks occurred in the weld heat affected zone of 8-inch to 10-inch type 304 material (schedule 10 and 40), initiating on the piping 1.D. surface and propagating in either an inter-granular or transgranular mode typical of Stress Corrosion Cracking.
Analysis indicated the probable corrocents to be chloride and oxygen contamination in the affected systems.
Plants affected up to this time were Arkansas Nuclear Unit 1, R. E. Ginna, H. B. Robinson Unit 2, Crystal River Unit 3, San Onofre Unit 1, and Surry Units 1 and 2.
The NRC issued Circular No. 76-06 (copy enclosed) in view of the apparent generic nature of the problem.
During the refueling outage of Three Mile Island Unit 1 which began in February of this year, visual inspections disclosed five (5) through-wall cracks at welds in the spent fuel cooling system piping and one (1) at a weld in the decay heat removal system.
These cracks were found as a result of local boric acid buildup and later confirmed by liquid penetrant tests.
This initial identification of cracking was reported to the NRC in a Licensee Event Report (LER) dated May 16, 1979.
A preliminary metallurgical analysis was performed by the licensee on a section of cracked and leaking weld j -
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R1 - Identifies those additions or te DUPLICATE DOCUMENT Entire document previously entered into system under:
ANO No.ofPahesE
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, NJ November 26, 1976 a
_2 II Circular No. 76-06 STRISS CORROSION CRACKS IN STACNANT, LOW PRISSURI STAIN 1.ESS PIPING CONTAINING BORIC ACID SOLUTION AT PVR's DESCRIPTION OF CIRCQ1 STANCES:
7 During the period Novenbar 7,1974 to November 1,1975, ceveral incidents of through-wall, cracking have occurred in the lO-inch, schedule 10 type 304 stainless steel piping of the Reactor Building Spray and Decay East Remova3 Systees at Arkansas Nuclear Plant No.1.
On October 7,1976, Virginia Electric and Power also reported through-
'vall cracking in the lO-inch schedule 40 type 30!. stainless dischar;e 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 zinilar to Unit 2.
On October 8,1976, another incident of similar cracking in 8-inth schedule 10 type 304 stainless piping of the Srfety injection Pump Suction Line st the Cinna facility was reported by the licensee.
Inforution received on the netallurgical analysis conducted to date indicates that the failures were the result of intergrenular stress corrosion crackin6 that initiated on the inside of the piping.
A cec =:nality of facters observed associated with the corrosion =e:ht. ism were:
1.
The cracks were adjacent to and propagated along weld zones of the thin-valled icv pressure piping, not part of the reactor coolant sys.em.
2.
Cracking occurred in piping containing relatively stagnant bori:
acid solution tot required for normal operating conditions.
3.
Analysis of surface products at this time indicate a chlori.te ion interaction with oxide formation in the relativaly stagnant ?.oric acid solution as the probable corrodant, with the state of stress probably due to velding and/or fabrication.
The source of the chloride ion is not dafinitely known.
Bowever,at ANO-1 the chlorides and sulfide level observed in the surface tarnish film near walds is believed to have been introduced into the piping during testing of the sodium thiosulfate discharge valves, or valve leakage.
Si=ilarly, at Ginna the chlorides and potential oxygen ourt1 cars oOcuacNr 12(11 151 Entire document previously entered into system under:
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