ML20151L883
| ML20151L883 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 07/28/1988 |
| From: | Hairston W ALABAMA POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| IEB-88-008, IEB-88-8, NUDOCS 8808040170 | |
| Download: ML20151L883 (4) | |
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Alatoma Power CompCny l
600 North 18th Street r-Post Off ce Box 2641 Birmingham, Alabams 352914400 Telephone 205 250-1837 W. G. Hairston, til Seruct Vke President I
Alabama Power the 50#ern ekctnc system July 28, 1988 Docket Nos. 50-348 50-364 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Vashington, DC 20555 Gentlemen:
J. M. Farley Nuclear Plant - Units 1 and 2 Thermal Stresses in Piping Connected to Reactor Coolant Systems - NRC Bulletin No. 88-08 Action 1 of NRC Bulletin No. 88-08 requests that Alabama Power Company reviev systems connected to the Reactor Coolant System (RCS) to determine whether unisolable sections of piping connected to the RCS can be subject to stresses f rom temperature stratification or temperature oscillations that could be induced by leaking valves and that were not evaluated in the design analysis of the piping. The bulletin allows 60 days for this review.
Action 2 requests that any unisolable sections of piping connected to the RCS that may have been subjected to excessive thermal stresses be examined nondestructively at the velds, heat-affected zones and high stress locations, including geometric discontinuities. to provide assurance that there are no existing flavs. The bulletin allows this Action to be completed before the end of the next refueling outage.
Action 3 requests that Alabama Power Company plan and implement a program to provide continuing assurance that unisolable sections of all piping connected to the RCS vill not be subjected to the enmbined cyclic and static thermal and other stresses that could cause fatigue failure during the remaining life of the unit. This assurance may be provided by instrumenting this piping to detect adverse temperature distributions and establishing appropriate limits on temperature distributions. This program, if required, should be implemented before the end of the next refueling outage.
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U. S. Nuclear Regulatory Commission July 28, 1988 Page 2 The bulletin further requires Alabama Power Company to submit a letter confirming the completion of Action 1, within 30 days of the completion of Action 1, and to include in the confirmatory letter a schedule for completing Actions 2 and 3 if the Action 1 review indicates that a potential problem exists.
Supplement 1 to the bulletin did not add any new requirements.
Unit 1 Action 1 - The review indicated the potential for the described thermal conditions to exist on the hot and cold leg safety injection lines. This Action is complete.
Action 2 - Vhen Unit 1 vas shut down for the eighth refueling outage (Spring 1988), susceptible velds vere nondestructively examined on the hot and cold leg safety injection lines using the enhanced ultrasonic technique presented to the NRC staff in the meeting held January 15, 1988 and documented by a February 8, 1988 memorandum by the NRC Project Manager for Farley.
No recordable indications vere found; however, one veld on "C" loop hot leg could not be nondestructively examined due to interference with a pipe support. This support vill be removed at the next refueling outage and the veld inspected. This examination was performed before the bulletin was issued.
During the next refueling outage, sections of the hot and cold leg injection lines, between the RCS and the first check valve from the RCS, vill be examined using the enhanced ultrasonic technique on velds, heat-affected zones and high stress locations, including geometric discontinuities.
Action 3 - Also during the eighth refueling outage, resistance temperature detectors (RTD's) vere installed on all three cold leg injection lines and all three hot leg injection lines. The RTD's vere installed on the top and bottom of each line, both upstream and downstream of the first check valve from the RCS. These RTD's have been monitored since plant startup from the refueling outage and no detrimental thermal conditions have been observed.
If temperatures deviate from the established ranges, an engineering evaluation vill be performed. The thermal effects which caused the initiation and propagation of the crack in Unit 2 are believed to have been caused by leakage from the Boron Injection Tank (BIT) bypass val',e.
The BIT bypass line in Unit 1 was cut and capped during the outage. The temperature sonitoring system is considered temporary.
A decision on a permanent installation vill be made prior to the end of the next refueling outage.
s U. S. Nuclear Regulatory Commission July 28, 1988 Page 3 Unit 2 Action 1 - The review Indicated the potential for the described thermal conditions to exist on the hot and cold leg safety injection lines. This Action is complete.
Action 2 - In December of 1987, while investigating the cause of the crack in the "B" loop cold leg injection line, velds in unisolable sections of all three cold leg injection lines were examined using the enhanced ultrasonic testing technique. No additional cracks were found. This inspection was conducted during the crack repair outage in an attempt to determine the extent of the problem.
Temperature stratification and temperature oscillations were discovered after the piping vas replaced and instrumented, and the unit began a return to power.
During the Unit 3 sixth refueling outage, sections of the hot and cold leg injection lines, between the RCS and the first check valve from the RCS, will be examined using the enhanced ultrasonic testing technique on velds, heat-affected zones and high stress locations, including geometric discontinuities.
Action 3 - As described to the NRC staff in a meeting held January 15, 1988, the "B" and "C" loop cold leg injection lines vere instrumented with RTD's when othat investigations failed to reveal a cause for the nipe crack. RTD's were placed on the "B" loop such that temperatures could be monitored at the sides of the pipe, in addition to the top and bottom of the pipe. These RTD's recorded the thermal effects which were determined to be the cause of the crack.
(The temperature stratification and i
oscillations were terminated by 111gning valves to create L
a path away from the RCS for the BIT bypass valve leakage.) The RTD's on the top and bottom of the "B" and "C" cold leg injection lines, upstrear and downstream of the first check valve from the RCS, are currently being monitored. This monitoring system is alne c ;.videred temporary.
A decision on a permanent installation vill i
be made prior to the end of the next.efueling outage.
During the sixth refueling outage, RTD's vill be added to the "A" 1000 cold leg injection line and to all three hot leg injection lines such that each line vill have RTD's top and bottom, upstream and downstream of the first check valve from the RCS. The Unit 2 BIT bypass line vill be cut and capped at the next outage of sufficient duration.
U. S. Nuclear Regulatory Commission July 28, 1988 Page 4 In summary, all requested activities will be completed by the end of the next refueling outage of each unit (Unit 1, ninth, Fall 1989; Unit 2, sixth, Spring 1989).
If there are any questions, please advise.
Respectfully submitted, ALABAHA POVER COMPANY al.A./
- .m V. G. Hairston, III VGH,III/RSF cc Mr. L. B. Long Dr. J. N. Grace Hr. E. A. Reeves Mr. V. H. Brndford SVORN TO AND SUBSCRIBED PEFORE HE THIS*f$ E AY OF Jot <
1988
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