ML19254F082
| ML19254F082 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 10/30/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Burstein S WISCONSIN ELECTRIC POWER CO. |
| References | |
| NUDOCS 7911060144 | |
| Download: ML19254F082 (1) | |
Text
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UNITED STATES e y ;'e c o,'g NUCLEAR REGULATORY COMMISSION i
e REGION it'
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8 799 ROOSEVELT RvAD k '.\\ /
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GLEN ELLYN. ILLINOIS 60137 g,,,
1979 Docket No. 50-266 Docket No. 50-301 Wisconsin Electric Power Company ATTN:
Mr. Sol Burstein s
Executive Vice President Power Plants 231 West Michigan Milwaukee, WI 53201 Gentlemen:
The enclosed IE Bulletin No. 79-17, Revision 1 is forwarded to you for action. A written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely,
% [ **
ames G. Keppler Director
Enclosure:
IE Bulletin No. 79-17, Revision I cc w/ encl:
Mr. G. A. Reed, Manager Central Files Director, NRR/DPM Director, NRR/ DOR C. M. Trammell, ORB /h1R PDR Local PDR NSIC IIC Sandra A. Bast, Lakeshore Citizens for Safe Energy 1291 158 7011060144
UNITED STATES SSINS do.
6820 NUCLEAR REGULATORY COMMISSION Accession No.
OFFICE OF INSPECTION AND ENFORCEMENT 7908220157 WASHINGTON, D.C.
20555 g
October 29, 1979 IE Bulletin No. 79-17 Revision 1
,s' PIPE CRACKS IN STAGNANT BORATED WATER SYSTEMS AT PWR PLANTS Description of Circumstances:
IE Bulletin No. 79-17, issued July 26, 1979, experienced to date in safety-related stainless steel piping systems at PWRprovi plants.
R1 license within a specified 90-day time frame.Certain actions were required o R1 R1 After several 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, may be impractical because of unavailability of qualified personnel in certain cases to complete the inspections within the time R1 specified by the Bulletin.
To alleviate this situation and allow licensees the R1 R1 resources of improved ultrasonic inspection capabilities, a time extension and clarifications to the bulletin have been made.
R1 affected items of the original bulletin.
These are referenced to the R1 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 corrodents 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 I 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.
and later confirmed by liquid penetrant tests.These cracks were found as a resul 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 jo' DUPLICATE DOCUMENT R1 - Identifies those additions or revi Entire document previously entered into system under.
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Nove:nber 26, 1976 IE Circular No. 76-06 STRESS CORROSICS CRACKS IN STACNANT, LOW PRESSURE STAIN 11.SS PIPING CONTAINING BORIC ACID SOLUTION AT PWR's DESCRIPTION OF CIRCC1 STANCES:
7 During the period November 7,1974 to November 1,1973, 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 Etat Remova3 Systems at Arkansas Nuclear Plant No.1.
On October 7,1976, Virginia Electric and Power also reported through-
'vall cratking in the 10-inch schedule 40 type 30!. stainless dischar;e piping of the "A" recirculation spray heat exchanger at Surry D=ft No. 2.
A recent inspection of Unit 1 Containment Recirculation Spray Piping revealed cracking sinilar tc Unit 2.
On October 8,1976, another incident of similar cracking in 8-inth schedule 10 type 304 stainless piping of the Srfety Injection Punp Suction Line se the Cinna facility was reported by the licensee.
Infot:.ation received on the netallurgical analysis conducted to date indicates that the failures were the result of intergrenular stress corrosion cracking that initiated on the inside of the piping.
A con:senality ef facters observed associated vicit the c:,rrosion =e:htr.isz were:
1.
The cracks were adjacent to and propagated along veld zones of the thin-valled low pressure piping, not part of the reactor coolant system.
2.
Cracking occurred in piping containing relatively stagnant hori:
acid solution not required for normal operating cenditions.
3.
Analysis of surface products at this time indicate a chloride ion interaction with oxide formation in the relatively stagnant boric acid solution as the probable corrodant, with the state of stress probably due to welding and/or fabrication.
The source of the chloride ion is not dafinitely kaos.2.
Bovever,at AND-1 the chlorides and sulfide level observed in the surface tarnish film near velds is believed to have been introduced into the piping during testics of the sodiu:n thiosulfate discharge valves, or vaive leakage.
Si=ilarly, at Ginna the chlorides and potential oxygen
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