ML19254F076
| ML19254F076 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 10/29/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Gerstner W ILLINOIS POWER CO. |
| References | |
| NUDOCS 7911060102 | |
| Download: ML19254F076 (1) | |
Text
p* * ' c
,'o, og UNITED STATES
- E'
' 7, NUCLEAR REGULATORY COMMISSION
, ~.
E REGION 111 e
o,
[
799 ROOSEVELT ROAD A/
0 0
GLEN ELLYN. ILLINOIS 60137
- ...+
Docket No. 50-461 Docket No. 50-462 Illinois Power Company ATTN:
Mr. W. C. Gerstner Executive Vice President 500 South 27th Street Decatur, IL 62525 Gentlemen:
The enclosed IE Bulletin No. 79-17, Revision 1 is forwarded to you for information. No written responsa 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,
[ames' & $
CL a,
G. Kepp er Director
Enclosure:
IE Bulletin No. 79-17, Revision 1 cc w/ encl:
Central Files Director, NRR/DPM Director, h7R/ DOR PDR Local PDR l'S IC TIC Mr. Dean Hansell, Office of Assistant Attorney General 129 1 9, 1
g d
7911060102 4
UNITED STATES SSINS No.
6820 NUCLEAR REGULATORY COMMISSION Accession No.
0FFICE OF INSPECTION AND ENFORCEMENT 7908220147 WASHINGTON, D.C.
20555 J
October 29, 1979 IE Bulletin No. 79-17 Revision 1 Y
PIPE CRACKS IN STAGNANT BORATED WATER SYSTEMS AT PWR PLANTS Description of Circumstances:
IE Bulletin No. 79-17, issued July 26, 1979, provided information on the cracking R1 experienced to date in safety related stainless steel piping systems at PWR R1 plants.
Certain actions were required of all DWR facilities with an operating license within a specified 90-day time frame.
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 R1 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.
To alleviate this situation and allow licensees the R1 resources of improved ultrasonic inspection capabilities, a time extension and R1 clarifications to the bulletin have been made.
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.0. 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 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 enant f al -- " --
R1 - Identifies those additions or revi DUPLICATE DOCUMENT Entire document previously entered into system under:
2}
}j8 ANO No. of pages:
]D dj November 26, 1976 h
~
IE Circular No. 76-06 STRISS CORROSION CRACKS IN STACNANT, LOW PRESSURE STAINLESS PIPING CONTAINING BORIC ACID SOLUTION AT PWR's DESCRIPTION OF CIRCD1 STANCES:
[
During the period November 7,1974 to November 1,1975, ceveral Lucidents of through-vall cracking have occurred in the 10-inch, schedule lo type 304 stainless steel piping of the Reactor Building Spray and Decay Eeat Remos a) Systems at Arkansas Nuclear Plant No.1.
On October 7,1976, Virginia Electric and Power also reported through-
'vaLL cracking in the 10-inch schedule 40 type 304 stainless discher;e piping of the "A" recirculation spray heat exchanger at Surry Unit No. 2.
A recent inspection of Unit 1 Containment Recirculation Spray PipinS revealed cracking similar 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 se 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 intergranular ctress corrosion cracking, that initiated on the inside of the piping.
/s co=m:nnlity ef facters observed associated with the corrosion =echt.. ism were:
1.
The cracks were adjacent to and propagated along weld zoner of the thin-valled low pressure piping, cot part of the reactor coolant system.
2.
Cracking occurred in piping containing re3atively stagnant hori:
acid solution tot required for normal operating cenditions.
3.
Analysis of surfece 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.
Bovever,,at ANO-1 the chlorides and sulfide level observed in the surface tarnish film naar velds is believed to have been introduced into the piping during testing of the sodium thiosulfate discharge valves, or vaive leakage.
Si=11arly, at Ginna the chlorides and potential cryget 129i 139 DUPLICATE DOCUMENT Entire document previously entered into system under:
h ANO No. of pages:
.