ML19247A580
| ML19247A580 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 07/17/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 7908010391 | |
| Download: ML19247A580 (1) | |
Text
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o UNITED STATES
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NUCLEAR REGULATORY COMMISSION
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. t REGION V 1990 N. CALIFORNI A BOULEVARD o, f6 j
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,,a WALNUT CREEK, CALIFORNI A 94596 July 17, 1979 Docket No. 50-344 Portland General Electric Company 121 S. W. Salmon Street Portland, Oregon 97204 Attention: Mr. Charles Goodwin, Jr.
Assistant Vice President Gentlemen:
This information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the information for possible applicability to their facilities.
No respcase is requested at this time, however, licensees should be aware that the NRC is evaluating the issuance of a Bulletin to operating PWRs requesting infomation on previous inservice inspections of stagnant borated water systems and requesting inspec-tion of systems which have not been inspected recently.
If you have questions or comments regarding this matter, please contact the Director of the appropriate NRC Regional Offi:e.
Sincerely, f3.-ea sm, M R. H. Engelken Director
Enclosure:
IE Information Notice No. 79-19 s
cc w/ enclosure:
S. Withers, PGE F. C. Gaides, PGE 620173 s
b 7 908010M l
UNITED STATES NUCLEAR REGULATORY C0?411SSICN OFFICE OF INSPECTION AND ENFORCE."ENT WASHINGTON, D. C.
20555 July 17, 1979 IE Information Notice t'o. 79-19 PIPE CRACKS IN STAGNANT BORATED WATER SYSTE?is AT PWR PLANTS Description of Circumstances:
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 portions of systems which contain oxygenated, stagnant or essentially stagnant borated water. Metallurgical investigations revealed these cracks occurred in the aeld heat affected zone of 8-inch to 10-inch type 304 naterial (schedule 10 and 40), initiating on the piping I.D. surface and propagating in either an intergranular or transgranular mcde typical of Stress Corrosion Cracking. Analysis incicated 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. Rob nson Unit 2, Crystal River Unit 3, San Onof re Unit 1, and Surry Units 1 and 2.
~he NRC issued Circular 76-06 (copy attached) in view of the apparent generic nature of the problen.
During the refuelina outage of Three Mile Isi'nd Unit I which began in February visual inspections disclosed f' <e (5) through-wall cracks at weMs of this year' fuel cooling system piping and c >e (1) at a weld in the decay he in the spent rencval systen.
These cracks were found as a result of local boric acid buil -
uo and later confirmed by liquid penetrant tests.
ihis initial identification o cr=cking was reported to the !iRC in a Licensee Event c port (LER) dated May 16, e
IN9.
A prelinirary metallurgical analysis was performed by the licensee cn a section of cracked and leaking weld joint frcm the scent fuel cooling system.
The conclusion of this analysis was that cracking was due p Intergranular Stress Cerrosion Crackinc (IGSCC) criginating cn the pipe t.D.
ine cracking was locali'ad to ' " Eea affected zone where the tyce :04 stainless steel is sensiti$ed (pkeEicitated carbides) during welf ng.
In addition to the rain
'Ihe"r~gh-wall crack, incipient cracks were cbserved at severdi locations in eld heat affected zone including the wel d rcot fusicn area where a miniscule lack of fusion had occurred.
The stresses responsible for cracking are believed to be prirarily residual welding stresses ir as much as tre cal ulated applied stresses were found to be less than code design linits.
gere is no conclusive evidenca at this tire to identify these aggressive chen,cai srecies which promoteEthisIGSCCattack.
Further analytical efforts in :hls arca and en cther systen welds is being pursue" y DUPLICATE DOCUMENT gg]
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