ML19290E484
| ML19290E484 | |
| Person / Time | |
|---|---|
| Issue date: | 02/26/1980 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Anderson V WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 8003140111 | |
| Download: ML19290E484 (3) | |
Text
4 DISTRIBUTION:
FEBRMY L 613s0 Docket / Central Files NRR Reading ORB #1 Reading ASchwencer CParrish WRoss TWambach Mr. V. S. Anderson Attorney, OELD Steam Turbine Division I&E (3)
Westinghouse Electric Corporation VNoonan Lester Branch, Box 9175 GKnighton Philadelphia, Pennsylvania 15230 TERA NSIC
Dear Mr. Anderson:
ACRS (16) and January 8,1980 you briefed the NRC staff and On December 17, 1979 representatives of several utilities on the subject of turbine disc At the con-cracks in Westinghouse turbines at nuclear power plants.the staff requested clusion of your presentation on December 17, 1979 j
your assistance in obtaining generic Westinghouse information that is On January 18, 1930 we briefly ct >f f and by licensees.
needed by th<
jou several areas where we require more information.
Enclosed are copies of general and site-specific requests for information discussed wi:
that have been transmitted to each of the licensees with plants on yourT
" AA" and "A" lists.
both the information and the safety significance of the information as part of their justification for continuing operation, or restarting operation, until their LP turbines can be fully inspected and all We have recommended that licensees make necessary corrections made.
use of an owners group to expedite the acquisition and analysis of generic Westinghouse information and to coordinate their responses.
We appreciate your continued cooperation in this matter.
Sincerely,
_9Niaal sagnad'by A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors Encicsure:
Request for Information Related to Turbine Disc Crack s T. M. Anderson, Westinghouse cc:
8003y4g((
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REQUEST FOR INFORMATION RELATED TO TURBINE DISCS SITE SPECIFIC GENERAL QUESTIONS - To Be Complcted in 20 Days I.
Provide the following information for each LP turbine:
A.
Turbine type B.
Number of hours of operation for each LP turbine at time of last turbine inspection or if not inspected, postulated to turbine inspection C.
Number of turbine trips and overspeeds D.
For each disc:
1.
type of material including material specifications 2.
tensile properties data 3.
toughness properties data including Fracture Appearance Transition Temperature and upper energy and temperature 4.
keyway temperatures 5.
calculated keyway crack size for turbine time specified in "B" above 6.
critical crack size 7.
ratio of calculated crack to critical crack size S.
crack growth rate 9.
calculated bore and keyway stress at operating design overspeed 10.
calculated K c data i
11.
minimur yield strength specified for each disc II.
Provide details of the results of any completed inservice inspection of LP turbine rotors, including areas examined, since issuance of an operating license.
For each indication detected, provide details of the location cf the crack, its orientation, and size.
III Provide the noninal water chemistry conditions for each LP turbine ano describe any condenser inleakages or other significant changes in secondary water chemistry tc this point in its operating life.
Discuss the occurrence of cracks in any given turbine as related to history of secondary water cnemistry in the unit.
IV.
If your plant has not been inspectec, describe your proposed schedule and approach to ensure that turbine cracking does not exist in your turbine.
V.
If your plant has been inspected and plans to return or has returned to po.ier with cracks, provide your proposed schedule for the next turbine inspection and the basis for this inspection schedule.
VI.
Indicate whether an analysis and evaluation regarding turbine missiles have been performed for your plant and provided to the staff.
If such an analysis and evaluation has been performed and reported, please provide appropriate references to the available documentation.
In the event that such studies have not been made, consideration should be given to scheduling such an action.
6 d
GENERIC QUESTIONS - To Be Comoleted in 20 Days I.
Describe what quality control and inspection proce:ures are used for the disc bore and keyway areas.
II.
Provide details of the Westinghouse repair / replace:ent procedures for the faulty discs.
III. What immediate and long term actions are being takan by Westinghouse to minimize future stress corrosion problems with turbine discs?
What actions are being recocnended to utilities to nininize stress corrosion cracking of discs?
I'Y.
Identify the impurities known to cause cracking in the low pressure turbines, and their sources.
Discuss the relationship between steam generator chemistry and steam chemistry relative t: the introduction of corrosive impurities into the turbine, inclucin; phospnate, AVT, ZST, and BWR chemistry. Discuss the mechanist of :eposition of these impurities that can lead to their concentratien ir, certain areas of keyways, and bores.
V.
What role does the refluxing action in the steam sicaration portion of the steam generator have on scrubbing corrosive im:eritie f rom the steam?
VI.
To what extent can the buildup of corrosive imourities in the LP turbine be alleviated? What would be the effects cf the following actions:
1.
Pumping moisture separator concensate to conde*.ser?
2.
Periodically moving point of concer.sation te p event localizec buildup of cerrosive impurities?
VII.
Describe f abrication and heat treatment secuence f:r discs, including thermal exposure during shrinking operations.
VIII.
Discuss the effects of any local residual stresses on the cracking mechanism.