ML19254F065
| ML19254F065 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 10/29/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Aswell D LOUISIANA POWER & LIGHT CO. |
| References | |
| NUDOCS 7911060045 | |
| Download: ML19254F065 (1) | |
Text
7 UNITED STATES
/pn pro,*o,,
v NUCLEAR REGULATORY COMMISSION
[h REGION IV p
< l o
611 RYAN PLAZA DRIVE, SulTE 1000 E,'
i[
ARLINGTON, TEXAS 76012 s -b g
- '+9 6
+,,,,9 October 29, 1979 In ^.eply Refer To:
RIV Docket No.
50-382/IE Bulletin No. 79-17, Revision 1 Louisiana Power and Light Co.
ATTN:
Mr. D. L. Aswell Vice President of Power Production 142 Delaronde Street New Oricans, Louisiana 70174 Gentlemen:
The enclosed IE Eulletin No. 79-17, Revision 1 is forwarded to you for information. No written response is required. Ilowever, the potential corrosion 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, Cb '.
N 4 IGrl V. Seyfrit Director
Enclosures:
1.
IE Bulletin No. 79-17 3 Revision 1 2.
List of IE Bulletins Issued in Last Six Months I?o2 086 innn e - -
! 4VU U4I 7911060045
UNITED STATES SSINS No.:
6820 NUCLEAR REGULATORY COMMISSION Accession No.:
OFFICE OF INSPECTION AND ENFORCEMENT 79082201$7 y
WASHINGTON, D.C.
20555 IE Bulletin No. 79-17 Revision 1 Date: October 29, 1979 Page 1 of 5 PIPE CRACKS IN STAGNANT BORATED WATER SYSTEMS AT PWR PLANTS Description of Circumstances:
E 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 PWR facilities with an operating R1 license within a specified 90-day time frame.
R1 After several discussions with licensee owner group representatives and R1 inspection agencies it has been determined that the requirements of Item 2, R1 particularly the ultrasonic examination, :nay be impractical because of R1 unavailability of qualified personnel in certain cases to complete the R1 inspections within the tiine specified by the Bulletin. To alleviate this R1 situation and allow licensees the resources of improved ultrasonic inspection R1 capabilities, a time extension and clarifications to the bulletin have been R1 made. Taese are referenced to the affected items of the original bulletin.
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 1.D. surface and propagating in either an inter-granular or transgranular mode typical of Stress Corrosion Cracking. Analysis indicated the probable carrodents to be chloride and oxygen contamination in the affected systems.
Plante 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 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. These cracks were foi e
and later confirmed by liquid penetra cracking was reported to the NRC in a 1979. A preliminary metallurgical an DUPLICATE DOCUMENT section of cracked and leaking weld j Entire document previously
]702 087 enterea into system under:
7 k2M[57 R1 - Identifies those addL 'ons or res ANO No. of pages
~
(
IE Circular 76-06 November 24, 1976
(
s STRESS CORROSION CRACKS IN STAGNANT, LOU PRESSURE STAINLESS PIPING CONIAINING EORIC ACID SOLUTION AT PUR's DESCRIPTION OF CIRCERIST!OCES:
During the period November 7,1974, to Noven'.ber 1,1975, several inci-dents of through-wall cracking hava occurred in the 10-inch, schedule ' '
10 type 304 stainless steel piping of the Reactor Building Spray and Decay Heat Systems at Arkansas nuclear Plant No. 1.
On October 7,1976 Virginia Elcetric and Power also reported through-uall cracking in the 10-inch schedule 40 type 304 stainless discharge piping of the "A" recirculation spray heat exchanger at Surry Unit No. 2.
A recent inspection of Unit No. 1 Containment Recirculation Spray Piping revealed cracking similar to Unit No. 2.
On October 8,1976, another incident of similar cracking in 8-inch sched-ele 10 type 304 stainless piping of the Safety injection Pucp Suction Line at the Ginna f acility was reported by the licensee.
Information received on the netallurgical analysis conducted to date indicates that the failures were the result of intergranular stress
/
corrosion cracidingthat initiated on the inside of the piping. A -
(
comonality of f actors observed associated with the corrosion mechanism were:
1.
The cracks were adjacent to and propagated along veld zones of the thin-walled low pressure piping, not part of the reactor coolant system.
2.
Cracking occurred in piping containing relatively stagnant boric acid solution not required for normal operating conditions.
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, uith the state of stress probably due to welding and/or fabrication.
~
I?o2 088 DUPLICATE DOCUMENT Entire document previously into system under:
enterec ANO l if
/b f
g i
< r N o. of,,as:
O