ML19254F075
| ML19254F075 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 10/29/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Hines E DETROIT EDISON CO. |
| References | |
| NUDOCS 7911060098 | |
| Download: ML19254F075 (1) | |
Text
.
t** "8 4
/p 9'o UNITED STATES 8'
NUCLEAR REGULATORY COMMISSION
.,y q
5 e
REGION lil
[
799 ROOSEVELT ROAD 4
o
%'..**0 0
GLEN ELLYN. lLLINOIS 60137 D U ' ' "' ' 70 Docket No. 50-341 The Detroit Edison Company ATTN:
Mr. Edward Hines, Assistant Vice President and Manager Quality Assurance 2000 Second Avenue Detroit, MI 48226 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,
$ $*Qk James G. KeppYer Director
Enclosure:
IE Bulletin No. 79-17, Revision 1 cc w/ encl:
Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Ronald Callen, Michigan Public Service Commission Eugene B. Thomas, Jr.,
Attorney 1291 131 M
7911 060098
UNITED STATES SSINS No.
6820 NUCLEAR REGULATORY COMMISSION Accession No.
OFFICE OF INSPECTION AND ENFORCEMENT 7908220187 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 PWRprovi plants.
R1 license within a specified 90-day time frame.Certain actions were required o 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 allow licensees the R1 resources of improved ultrasonic inspection capabilities, a time extension and t'arifications to the bulletin have been made.
R1 a1fected 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), in:tiating 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.
The NRC issued Circular No. 76-06 (copy enclosed) in view of the apparent generic nature of the problem.
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.
These cracks were found as a result of local boric acid buildup and later confirmed by liquid penetrant tests.
This initial identification of tracking was reported to the NRC in a Licensee Event Report (LER) dated May If>,
1979.
A preliminary metallurgical analysis was performed b the li section of cracked and leaking weld jo" DUPLICATE DOCUMENT R1 - Identifies those additions or rev Entire document previously entered into system under:
ANO N
~
- 4 N o. of pages:
129 132 1
f November 26, 1976 IE Circular No. 76-06 STRESS CORROSION CRACKS IN STAGNANT, LOW PRESSURI STAINLESS PIPING CONTAINING BORIC ACID SOLUTION AT PWR's DESCRIPTION OF CIRCt?1 STANCES:
s During the period November 7,1974 to November 1,1975, ceveral incidents of through-vall, cracking have occurred in the lO-inch, schedule 10 type 304 stainless steel piping of the Reactor Building Spray and Decay East Remova) Systems at Arkansas Nuclear Plant No.1.
On October 7,1976, Virginia Electric and Power also reported through-
~
wall cracking in the 10-inch schedule 40 type 30/. 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 8-inch schedule 10 type 304 stainless piping of the Srfety injection Punp Suction Line st the Cinna facility was reported by the licensee.
Infor:.ation received on the metallurgical analysis conducted to date indicates that the failures were the result of intergrcnular ctress corrosion cracking that initiated on the inside of the piping.
A cor.;t:nality of facters observed associated vicit the corrosion =echu.isn were:
1.
The cracks were adjace=t to and propagated along ueld zoner of the thin-valled low pressure piping, not part of the reactor coola:t system.
2.
Cracking occurred in piping containing re3atively 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 relativaly 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 knovn.
Bovaver,,at ANO-1 the chlorides and sulfide level observed in the surface tarr.ish film near velds is believed to '. ave been introduced into the piping during casting of the sodium thiosulfate discharge valves, or valve leakage.
S4-41arly, at Ginns the chlorides and potential oxygen DUPLICATE DOCUMENT Entire document previously 7
1291 13"3 enterea into system under.
ANO b
No. of Pages-
-.