ML19254F068
| ML19254F068 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Byron, Braidwood, Quad Cities, LaSalle  |
| Issue date: | 10/30/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Reed C COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 7911060052 | |
| Download: ML19254F068 (1) | |
Text
[pn naam#'o, UNITED STATES
' 7, NUCLEAR REGULATORY COMMISSION REGION 111
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e' GLEN ELLYN ILLINOIS 60137
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o.s Docket Nos. 50-10, 50-237, 50-249, 50-254, 50-265, 50-373, 50-374, 50-454, 50-455, 50-456 and 50-457 Commonwealth Edison Company ATTN:
Mr. Cordell Reed Manager of Nuclear Operations Post Office Box 767 Chicago, IL 60690 Gentlemen:
The enclosed IE Bulletin No. 79-17, Revision 1 is forwarded to you for information. No written response is required. However, the pot encial 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, W/
v James G. Keppler /
Director
Enclosure:
IE Bulletin No. 79-17, Revision 1 cc w/ enc 1:
Mr. D. L. Peoples, Director Mr. R. Cosaro, Project of Nuclear Licensing Superintendent Mr. B. B. Stephenson, Central Files Station Superintendent Director, NRR/DPM Mr. N. Kalivianakis, Director, NRR/ DOR Station Superintendent PDR Mr. L. J. Burke, Site Local PDR Project Superintendent NSIC Mr. T. E. Quaka, Quality TIC Assurance Supervisor Anthony Roisman, Esq., Attorney Mr. R. H. Holyoak, Station Mr. Dean Hansell, Office of Superintendent Assistant Attorney General Mr. Gunner Sorensen, Site Project Superintendent
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icvu v00 1291 107 7911060 052
UNITED STATES 551N5 No.
6820 NUCLEAR REGULATORY COMMISSION Accession No.
OFFICE OF INSPECTION AND ENFORCEMENT79082201$7 WASHINGTON, D.C.
20555 g
October 29, 1979 IE Bulletin No. 79-17 Revision 1 s'
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.
R1 To alleviate this situation and allow licensees the 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.
of the apparent generic nature of the problem.The NRC issued Circular No. 76-0 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.
and later confirmed by liquid penetrant tests.These cracks were found as a resu 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 joint from the spent fuel coolino system.
R1 - Identifies those additions or revi DUPLICATE DOCUMENT Entire document previously entered into system under:
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O November 26, 1976 IE Circular No. 76-06 STRISS CORROSION CRACK.S IN STACNANT,14W PRESSURE STAINLESS PIPING CONTAINING BORIC ACID SOLUTION AT PWR's DESCRIPTION OF CIRCD1 STANCES:
g During the period November 7,1974 to November 1,1975, ceveral incident's of through-vall, cracking have occurred in the 10-inch, schedule 10 type 304 stainlass steel piping of the Reactor Building Spray and Deca:- Eeat Remova) Systems at Arkansas Nuclear Plant No. 1.
On October 7,1976, Virginia 7.lectric and Power aise, reported through-
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wall cracking in the 10-inch schedule 40 type 301. stainless dischar;e piping of the "A" recirculation spray heat exchanger at Surry Deft No. 2.
A recent inspection of Unit 1 Containment Recirculation Spray Piping revealed cracking sinilar to Unit 2.
On October 8,1,76, another incident of similar cracking in 8-inth schedule 10 type 304 stainless picing of the Srfety injection Pump Suction Line st the Cinna facility was, raported by the licensee.
Inforration received on the natallurgical analysis conducted to date indicates that the failures were the result of intergrenular etress corrosion crackint, that initiated on the inside of the piping.
A cecm:nality ef facters ebserved associated with the corrosion =e:htr.ist were:
1.
The cracks were adjacent to and propagated along weld zoner of the thin-valled low pressure piping, not part of the reactor coolant system.
2.
Cracking occurred in piping containing relatively stagnant bori:
acid solution not required for normal operating conditions.
3.
Analysis of surface products 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 strass probably due to velding and/or f abrication.
The source of the chloride ion is not dafinitely known.
Bovever,at ANo-1 the chlorides and sulfide level observed in the surface tarnish film near valds 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 oxyget DUPLICATE DOCUMENT 1291
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