ML19259C641
| ML19259C641 | |
| Person / Time | |
|---|---|
| Site: | Robinson, Brunswick  |
| Issue date: | 07/26/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Jackie Jones CAROLINA POWER & LIGHT CO. |
| References | |
| NUDOCS 7908070727 | |
| Download: ML19259C641 (2) | |
Text
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NUCLEAR REGULATORY COMMISSION 8
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101 MARIETT A ST., N W., SUIT E 3100 ATLANT A, GEORGI A 00303 C
g JUL 2 61979 In Reply Refer To:
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50-261 Carolina Power and Light Company ATTN:
Mr. J. A. Jones Executive Vice President and Chief Operating Officer 411 Fayetteville Street Raleigh, NC 27602 Gentlemen:
The enclosed Bulletin 79-17 is forwarded to you for action. A written response is required.
If you desire additional informa*-.. regarding this matter, please contact this office.
Sincerely,
$h s,
ts. James P. O'Rei y Director Enclosure :
IE Bulletin 79-17 2107
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Carolina Power and Light Company cc w/ encl:
A. C. Tollison, Jr.
Plant Manager Box 458 Southport, North Carolina 28461 R. B. Starkey, Jr., Plant Manager Post Office Box 790 Hartsville, South Carolina 29550
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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C.
20555 July 26, 1979 IE Bulletin No. 79-17 PlPE CRACKS IN STAGNANT BORATED WATER SYSTEMS AT PWR PLANTS Description of Circumstances:
During the period of November 1974 to February 1917 a number of cracking incidents have been experienced in safety-related stainless steel piping systems and stagnant or essentially stagnant portions of systems which contain oxygenated, revealed these cracks occurred in borated water. Metallurgical investigations 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 transgranular mode typical of Stress Corrosion Cracking.
intergranular or Analysis indicated the probable corrodents to be chloride and oxygen contami-Plants affected up to this time were Arkansas nation in the affected systems.
Nuclear Unit 1, R. E. Giana, H.B. Robinson Unit 2, Crystal River Unit 3, San Onofre Unit 1, and Surry Units 1 and 2.
The NRC issued Circular 76-06 (copy attached) in view of the apparent generic nature of the problem.
I which began in February During the refueling outage of Three Mile Island Unit of this year, visual inspections disclosed five (5) through-wall cracks at welds fuel cooling system piping and one (1) at a weld in the decay heat in the spent These cracks were found as a result of local boric acid build-removal system.
This initial identification up and later confirmed by liquid penetrant tests.
(LER) dated May of cracking was reported to the NRC in a Licensee Event Report A preliminary metallurgical analysis was performed by the licensee on 16, 1919.
fuel cooling system.
a section of cracked and leaking weld joint from the spent conclusion of this analysis was that cracking was due to Intergranular The 1.D.
The cracking Stress Corrosion Cracking (IGSCC) criginating on the pipe affected zene where the type 304 stainless steel is was localized to the heat during welding.
In addition to the main sensitized (precipitat ed carbides) cracks were observed at several locations in the through-wall crack, incipient fusion area where a miniscule weld heat affected zone including the weld root The stresses responsible for cracking are believed lack of fusion had occurred.
to be primarily residual welding stresses in as much as the calculated applied There is no conclusive stresses were found to be less than code design limits.
evidence at this time to identify those aggressive chemical species which promoted Further analytical efforts in this area and on other system this IGSCC attack.
welds are being pursued.
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