ML19254F081
| ML19254F081 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/30/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Crouse R TOLEDO EDISON CO. |
| References | |
| NUDOCS 7911060140 | |
| Download: ML19254F081 (1) | |
Text
y[
[o, UNITED STATES s ~,, 7 g
NUCLEAR REGULATORY COMMISSION e
r, e
REGION lli
[
799 ROOSEVE LT ROAD
%, ' \\/ [p
O, GLEN ELLYN. ILLINOIS 60137
- ...+
0'~ 3 1979 Docket No. 50-346 Toledo Edison Company ATTN:
Mr. Richard P. Crouse s
Vice President Energy Supply Edison Plaza 300 Madison Avenue Toledo, OH 43652 Gentlemen:
The enclosed IE Bulletin No. 79-17, Revision 1 is forwarded to you for action A written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, b
/
a~
James G. Keppler Director
Enclosure:
IE Bulletin No. 79-17, Revision 1 cc w/ encl:
Mr. T. D. Murray, Station Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Harol3 W. Kohn, Power Siting Commission Helen W. Evans, State of Ohio 1291 155 7911060140
UNITED STATES 551NS No.
6820 NUCLEAR REGULATORY COMMISSION Accession No.
0FFICE OF INSPECTION AND ENFORCEMENT 79082201(7 WASHINGTON, D.C.
20555 3
October 29, 1979 IE Bulletin No. 79-17 Revision 1 8
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 of 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 complete the inspections within the time R1 specified by the Bulletin.
R1 To alleviate this situation and allcw licensees the R1 resources of improved ultrasonic inspection capabilities, a time extension and clarifications to the bul!etin 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 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 res 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 R1 - Identifies those additions or revi DUPLICATE DOCUMENT Entire document previously entered into system under.
1291 156 xso79p W )W 37 No. of Pages:
D
w u
November 26, 1976 IE Circular No. 76-06 STRESS CORROSION CRACKS IN STACNANT, I M FRE55URE STAIN 1.ESS PIPING CONTAINING BORIC ACID SOLUTION AT P9R's DESCRIPTION OF CIRCU11 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 stainless staal piping of the Reactor Building Spray and Decay East Re= ova) Systems at Arkansas Nuclear Plant No.1.
On October 7,1976, Virginia Electric and Power niso reported through-vali cracking in the 10-inch schedule 40 type 304 stainless dischar;e piping of the "A" recirculation spray heat exchanger at Surry Onft 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 similar cracking in 8-i=th schedule 10 type 304 stainless piping of the S-fety injection Pu p Suctson Line st the Cinna facility was reported by the licensee.
Infotr.ation received on the metallurgical analysis conducted to date indicates that the failures were the result of intergrenular stress corrosic,n cracking, that initiated on the inside of the piping.
A co=monality of facters observed ascociated with the corrosion =echer.iss were:
1.
The cracks were adjacent to and propagated along weld zones 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 :ot 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 soures of the chloride ton is not dafinitely known.
Bowever,at ANO-1 the chlorides and sulfide leva observed in the surface tarnish film near velds is believed to have been introduced into the piping during testing of the sodium thiosulfate discharge valves, or valve leakage.
Si=ilarly, at Cinna the chlorides and potential oxygen
~
1291 157 DUPLICATE DOCUMENT Entire document previously entered into system under:
!b
[
ANO c
(
{/)
No. of pages:
1
. a