ML19254F070
| ML19254F070 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 10/29/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Borgmann E CINCINNATI GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7911060080 | |
| Download: ML19254F070 (1) | |
Text
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.m ano UNITED STATES E
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NUCLEAR REGULATORY COMMISSION g, / -
c REGION 111 o,. ~ ~
f 799 ROOSEVELT HoAD U
o GLEN ELLYN. ILLINOIS 60137
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Docket No. 50-358
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.U 7,3 Cincinnati Gas and Electric Company ATTN:
Mr. Earl A. Borgmann Senior Vice President Engineering Services and Electric Production 139 East 4th Street Cincinnati, OH 45201 Gentlem f 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, ss.h lf~ A JamesG.KeMer Director
Enclosure:
IE Bulletin No. 79-17, Revision 1 cc w/ encl:
Mr. J. R. Schott, Plant Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Harold W. Kohn, Power Siting Commission j29j} Citizens Against a Radioactive Environment Helen W. Evans, State of Ohio 7911 060080
UNITED STATES SSINS No. 6820 NUCLEAR REGULATORY COMMISSION Accession No. OFFICE OF INSPECTION AND ENFORCEMENT 7908220157 WASHINGTON, D.C. 20555 3 October 29, 1979 IE Bulletin No. 79-17 Revision 1 [ 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 PWRprov plants. license within a specified 90-day time frame.Certain actions were required o R1 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 unavailability of R1 qualified personnel in certain cases to coraplete the inspections within the time R1 specified by the Belletin. 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 syster.s 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.0. surface and propagating in either an inter-granular or transgranular mode typical of Stress Corrosion Cracking. indicated the probable corrodents to be chloride and oxygen contamination in the Analysis 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 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 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 jo' R1 - Identifies those additions or rev DUPLICATE DOCUMENT Entire document previoucly entered into system under: ANO am r
ma 9 9 ogiq \\( bd o 3 November 26, 1976 IE Circular No. 76-06 STRESS CORROSION CRACKS IN STACNANT, IDW PRESSURE STAIh*1.ESS PIPING CONTAINING BORIC ACID SOLUTION AT PWR's DESCRIPTION OF CIRCQ1 STANCES: [ During the period November 7,1974 to November 1,1975, ceveral incidents of through-vall cracking have occurred in the 10-inch, schedule 10 type 304 stainlass st' eel piping of the Raactor Building Spray and Decay Eeat Re= ova) Systems at Arkansas Nuclear Plant No. On October 7,1976, Virginia 7.lectric and Power also reported through-vall cracking in the 10-inch schedule 40 type 304 stainless dischar;e piping of the "A" recirculation spray heat exchanger at Surry Unit No. 2. A recent inspection of Unit 1 Containment Recirculation Spray Piping revealed cracking zinilar to Unit 2. On October 8,1976, another incident of similar cracking in S-inch schedule 10 type 304 stainless piping of the Srfety injection Punp Suction Line tt the Cinna facility was reported by the licensee. Inferr.ation received on the metallurgical analysis conducted to date indicates that the failures were the result of intergrenular ctress corrosion cracking that initiated on the inside of the piping. A coc=:nnlity ef facters observed associated with the corrosion =echt:1s2 were: 1. The cracks were adjacent to and propagated along veld 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 tot 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 velding and/or fabrication. The source of the chloride ion is not dafinitely known. Bovaver,,et 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 tasting of the sodium thiosulfate discharge valves, or vaive leakage. 54-41arly, at Cinna the chlorides and potential oxygen ourticnTE oOcuxENT I291 115 Entire document previously entered into system under: $NlWYW ANO 12 f N o. of pages: (O .}}