ML19254F072
| ML19254F072 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 10/30/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Dewitt R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 7911060084 | |
| Download: ML19254F072 (1) | |
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UNITED STATES j
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o GLEN ELLYN. ILLINOIS 60137 Docket No. 50-155 bl' ! ' bl9 Consumers Power Company ATTN:
Mr. R. B. DeWitt Vice Presider.t s
Nuclear Operations 212 West Michigan Avenue Jackson, MI 49201 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, kn 0 -
James G. Keppler Director
Enclosure:
IE Bulletin No. 79-17, Revision 1 cc w/ encl:
Mr. C. J. Hartman, Plant Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Ronald Callen, Michigan Public Service Commission Anthony Roisman, Esq.,
l } g; l ll Attorney 7911060084
UNITED STATES SSINS No.
6820 NUCLEAR REGULATORY COMMISSION Accession No.
OFFICE OF INSPECTION AND ENFORCEMENT 7908220157 WASHINGTON, D.C.
20555 j
October 29, 1979 IE Bulletin No. 79-17 Revision 1 s',
PIPE CRACKS IN STAGNANT BORATED WATER SYSTEMS AT PWR PLANTS s
Description of Circumstances:
IE Bulletin No. 79-17, issued July 26, 1979, experienced to date in safety-related stainless steel piping systems at PWRprov plants.
R1 Certain actions were required of all PWR facilities with an operating license within a specified 90-day time frame.
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 the ultrasonic examination, may be impractical because of unavai! ability of R1 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 I.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 cooling system.
R1 - Identifies those additions or revis M DUPLICATE DOCUMENT Entire document previously entered into system under:
ANO N
1291 120 No.orJeoes:
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O November 26, 1976 IE Circular do. 76-06 STRESS CORROSION CRACKS IN STACNANT, IDW PRISSURE STAIh*LESS PIPING CONTAINING BORIC ACID SOLUTION AT PWR's DESCRIPTION OF CIRCD1 STANCES:
During the period November 7,1974 to November 1,1975, ceveral incidents of through-wall cracking have occurred in the IO-inch, schedule 10 type 304 stainless steel piping of the Reactor Building Spray and Decay East Re= ova) Systems at Arkansas Nuclear Plant No. 1.
On October 7,1976, Virginia Ilectric and Power also reported through-
'vall cracking in the 10-inch schedule 40 type 301. stainless dischar;e piping of che "A" recirculation spray heat exchanger at Surry Unit No. 2.
A recent inspection of Unit 1 Containment Recirculation Spray Piping revealed cracking similar to Unit 2.
On October 8,1976, another incident of similer cracking in 8-inth schedule 10 type 304 stainless piping of the Srfety injection Pu:p Suction Line se the Cinna facility van, reported by the licensee.
Infor:.ation received on the metallurgical analysis conducted to date indicates that the failures were the result of intergrenular ccress corrosion cracking, that initiated on the inside of the piping.
A co=m:nclity of facters observed associated with the corrosion = ether. ism 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 boric acid solution cot required for normal operating cenditions.
3.
Analysis of surface products at thir time indicate a chloride ion interaction with oxide fonr.ation in the relatively stagnant boric acid solution as the probable corrodant, with the state of stress probably due to walding and/or fabrication.
The source of the chloride ion is not dafinitely known.
Bovaver,,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 tasting of the sodium thiosulfate discharge valves, or valve leakage.
Si=ilarly, at Ginns the chlorides and potential oxygen DUPLICATE DOCUMENT Entire document previously entered into system under:
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