ML19247A585
| ML19247A585 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 07/17/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Clayton F ALABAMA POWER CO. |
| References | |
| NUDOCS 7908010399 | |
| Download: ML19247A585 (2) | |
Text
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'As JUL 17 1979 In Reply Refer To:
RII:JPO 50-348 50-364 Alabama Power Company Attn:
F. L. Clayton, Jr.
Executive Vice President Post Of fice Box 2641 Birmingha=, Alabama 35291 Gentlemen:
This Information Notice is provided as an early notification of ais expecte It possibly significant matter.
i No the information f or possible applicability to their f acilit es.
response is requested at this time however licensees should be aware ting PWR's that the NRC is evaluating the issuance of a Bulletin to opera requesting information on previous inservice inspections of stagnant borated water systems and requesting inspection of systens which not been inspected recently.
C Pegional this matter, please contact the Director of the appropriate NR Office.
Sincerely, e
W K James P. O' Reil y Director
Enclosure:
1.
IE Inf or=ation Notice No. 79-19 2.
Listing of IE Informatica Notices Issued in 1979 C
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JUL 171979
. Alabama Power Company cc w/ encl:
A. R. Barton Executive Vice President Post Office Box 2641 Birmingham, Alabama 35291 J. T. Youog Vice President-Production Post Office Box 2641 Birmingham, Alabama 35291 C. Biddinger, Jr.
Manager-Corporate Quality Assurance Post Office Box 2641 Birmingham, Alabama 35291 H. O. Thrash Manager-Nuclear Generation Post Office Box 2641 B.rmingham, Alabama 35291 H. G. Eairston, III Plant Manager Drawer 470 Ashford, Alabama 36312 R. E. Hollands, Jr.
QA Supervisor Post Office Box U Ashford, Alabama 36312 402 257
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINCTON, D. C.
20555 July 17, 1979 IE Information Notice No. 79-19 PIPE CRACKS IN STAGNANT BORATED WATER SYSTEMS AT PWR PLANTS Desc.ription of Circumstances:
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 portions of systems which contain oxygenated, stagnant or essentially stagnant borated water. Metallurgical investigations revealed these cracks occurred in the weld heat affected zone of 8-inen to 10-inch type 304 material (schedule 10 and 40), initiating on the piping I.D. surface and propagating in either an intergranular or transgranular mode typical of Stress Corrosion Cracking. Analysis indicated the probable corrodents to be chloride and oxygen contamination in the affected systems. Plants af fected 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 76-06 (copy attached) in view cf 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 velds in the spent fuel cooling system piping and one (1) at a weld in the decay heat removal syntem. These cracks were found as a result of local beric acid build-up 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 metsllurgical analysis was performed by the licensee on a section of cracked and leaking veld joint from the spent fuel cooling system.
The conc.usion of this analysis was that cracking was due to Intergranular Stress Corrosion Cracking (ICSCC) originating on the pipe I.D.
The cracking was localized to the heat affected zone where the type 304 ctainless steel is sensitized (precipitated carbidesj during welding.
In addition to the main through-wall crack, incipient reacks were observed at several locations in the weld heat affected zone including the weld root fusion area where a miniscule lack of fusion had occurred. The stresses responsible for cracking are believed to be primarily residual welding stresses in as much as the calculated applied stresses were found to be less than code design limits.
There is no conclusive evidence at this time to identify those aggressive chemical species which promoted this ICSCC attack. Further analytical efforts in this area and on other system welds is being pursued.
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IE Information Notice No. 79-19 July 17, 1979 Page 2 of 2 Based on the above analysis and visual leaks, the licensee initiated a broad based ultrasonic examination of potentially affected systems utilizing special techniques. The systems examined included the spent fuel, decay heat removal, makeup and purification, and reactor building spray systems which contain stagnant or intermittently stagnant, oxygenated boric acid environ-ments.
These systems range f rom 2 1/2-inch (HPCI) to 24-inch (borated water storage tank suction), are type 304 stainless steel, schedule 160 to schedule 40 thickness respectively.
Results of these examinations were reported to the NRC on June 30, 1979 as an update to the May 16, 1979 LER.
The ultrasonic inspection as of July 10, 1979 has identified 206 welds cut of 946 inspected having UT indications characteristic of cracking randomly distributed throughout the aforementioned sizes (24"-14"-12"-10"-8"-2" etc.)
of the above systems.
It is important to note that six of the crack indications were found in 21/2-inch diameter pipe of the high pressure injection lines inside containment. These lines are attached to the main coolant pipe and are nonisolable from the main coolant system except for check valves. All of the six cracks were found in two high pressure injection lines containing stagnated borated water. No cracks were found in the high preseure injection lines which were occasionally flushed during nakeup operations. The ultrasonic examination is continuing in order to delineate the extent of the problem.
Enclosures:
1.
List of Information Notices Issued in 1979 2
2
IE Information Notice No. 79-19 July 17, 1979 Page 1 of 2 LISTING OF IE INFORMATION NOTICES ISSUED IN 1979 In fo rmation Subject Date Issued To Notice No.
Issued 79-01 Bergen-Paterson liydraulic 2/2/79 All power reactor Shock and Sway Arrestor facilities with an OL or a CP 79-02 Attempted Extortion -
2/2/79 All Fuel Facilities Low Enriched Uranium 79-03 Limitorque Valve Geared 2/9/79 All power reactor Limit Switch Lubricant facilities with an OL or a CP 7 9- 04 Degradation of 2/15/79 All power reactor Engineered f acilities with an Safety Features OL or a CP 79-05 Use of Lnproper Materials 3/21/79 All power reactor in Safety-Related Components facilities with an OL or CP 79-06 Stress Analysis of 3/23/79 All Holders of Safety-Related Piping Reactor OL or CP 79-07 Rupture of Radwaste Tanks 3/26/79 All power reactor facilities with an OL or CP 79-08 Interconnection of 3/28/79 All power reactor Contaminated Systems wid facilities with an Service Air Systems Used OL and Pu Processing As the Source of Breathing fuel facilities Air 79-09 Spill of Radioactively 3/30/79 All power reactor Contaminated Resin f acilities with an OL 79-10 Nonconforming Pipe 4/16/79 All power reactor Support Struts facilities with a CP 79-11 Lower Reactor Vessel Head 5/7/79 All 1 Iders of Reactor Insulecion Support Problem OLs and cps I0]
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IE Information Notice No. 79-19 July 17, 1979 Page 2 of 2 LI5 TING OF IE INFORMATION NOTICES ISSUED IN 1979 Information Subject Date Issued To Notice No.
Issued 79-12 Attempted Damage to New 5/11/79 All Fuel Facilities Fuel Assemblies Research Reactors, and Power Reactors with an OL or CP 79-13 Indication of Low Water 5/29;'79 All Holders of Reactor Level in the Oyster Creek CLs and cps Reactor 79-14 NRC Position of Electrical 6/11/79 All Power Reactor Cable Support Systems Facilities with a CP 79-15 Deficient Procedures 6/7/79 All Holders of Reactor OLs and cps 79-16 Nuclear Incident at Three 6/22/79 All Research Reactors Mile Island and Test Reactors with OLs 79-17 Source Holder Assembly Damage 6/20/79 All Holders of Reactor Damage Frem Mie
't Between OLs and cps Assembly and Reactor Upper Crid Plate 79-18 Skylab Reentry 7/5/79 All Holders of Reactor OLs
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