ML19330B738
| ML19330B738 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 08/01/1980 |
| From: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19330B739 | List: |
| References | |
| TASK-03-04.B, TASK-3-4.B, TASK-RR NUDOCS 8008050436 | |
| Download: ML19330B738 (6) | |
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,J August 1, 1980 Director, Nuclear Reactor Regulation Att Mr Dennis M Crutchfield, Chief Operating Projects Branch No 5 U S Nuclear Regulatory Co==ission Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - RESPONSE TO ENCLOSURE 3 0F NRC LETTER DATED JUNE 11, 1980 - REQUEST FOR INFORMATION RELATED TO TURBINE DISCS By letter dated June 11, 1980, the NRC requested information, enclosure 3 to the letter, on low-pressure turbines manufactured by General Electric. The staff's intent being to learn more about the underlying reasons for turbine disc indica-tions found, the probable rate of growth of these indications and their effects on turbine disc integrity.
Consumers Power Company has reviewed the attachments supplied by the request for information and finds that the concerns stated do not apply to Big Rock Point for the following reasons:
Big Rock Point's Lov Pressure (LP) turbine is of a design that does not use dises.
Both the High Pressure (HP) and LP turbines are of an integral wheel type construc-tion made from solid forgings without separate discs shrunk onto the turbine shaft.
Also, the orientation of the turbine relative to containment, "end-on" configura-tion, precludes turbine missiles consideration for containment., attached, is being sut=itted for informational purposes for use by your staff. The original telecopy was not received and in obtaining information from General Electric, a delay was encountered which necessitated a delay in our reply. Mr Walter Paul.acn of your staff was informed of the delay and accepted it.
David P Hofman (Signed)
David P Hoffman Nuclear Licensing Administrator CC Director, Region III, USNRC NRC Resident Inspector - Big Rock Point Attachment 8 0080 50 M
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CONSUMERS POWER COMPAIN Big Rock Point Plant of NRC Letter Dated June 11, 1980 Docket 50-155 License DPR-6 At the request of the Commission and pursuant to the Atomic Energy Act of 1954, and the Energy Reorganization Act of 1974, as amended, and the.Coc=ission's Rules and Regulations thereunder, Consumers Power Company submits our response to Enclos-ure 3 entitled, " Request for Information Related to Turbine Dises" of NRC letter dated June 11, 1980. Consumers Power Company's response is dated August 1, 1980 CONSUMERS POWER COMPANY By R C Youngdahl (Signed)
R C Youngdahl, Executive Vice President Sworn and subscribed before me this 1st day of August, 1980.
Linda K Carstens (Signed)
Linda K Carstens, notary Public (SEAL)
Jackson County, Michigan My commission expires June 10, 1981.
RESPONSE TO ENCLOSURE 3 REQUEST FOR INFORMATION RELATED TO TURBINE DISCS SITE SPECIFIC GENERAL QUESTIONS ITEM I Provide the following information for each low pressure (LP) turbine:
A.
Turbine type:
Response
The Consumers Power Company's Big Rock Point Plant consists of one tandem compound, two flow, two casing, condensing 3600 RPM turbine.
A cross section of this turbine is shown on the attached turbine assembly drawing, numbered 2127526. This turbine was designed and manufactured by General Electric's Medium Steam Turbine Generator Department in Lynn, MA.
This turbine is distinctly different in design from turbines manufactured by General Electric's Large Steam Turbine Generator Department.
B.
Number of hours of operation for each LP turbine at the time of the' last turbine inspection or if not inspected, postulated to turbine inspection:
Response
The turbine has been operated 102,031 hours3.587963e-4 days <br />0.00861 hours <br />5.125661e-5 weeks <br />1.17955e-5 months <br /> through June 30, 1980.
No turbine disc inspection is possible due to the lack of turbine discs.
C.
Number of trips and overspeeds:
Response
The turbine emergency governor overspeed trip is tested at actual overspeed annually per the vendor's recommendation. Additionally, there has been one overspeed of the unit to the trip set point. Thus, there have been a total of approximately 18 overspeeds to the110 - 112.2%
overspeed range (3960 to hoho RPM).
D.
For each dise:
Response
The Big Rock Point turbine has no dises. Both the High Pressure (HP) and Low Pressure (LP) turbines are of an integral wheel type construction made from solid forgins. There are no separate discs shrunk on the shaft. The LP is constructed from a singleforgings due to the small size of this unit (turbine nameplate rating 5h,500 kW). Information on the LP rotor material has been provided by General Electric to Consumers Power Company. This information is considered proprietary by General Electric and can be provid-ed upon request as proprietary information.
1.
Type of material including material specifications:
Restonse The Big Rock Point LP turbine has no discs.
n.
2 2.
Tensile properties data:
Response
The Big Rock Point LP turbine has no dises.
3.
Toughness properties data including Fracture Appearance Transition Temperature and Charpy Upper Steel Energy and Temperature:
Response
The Big Rock Point LP turbine has no dises.
h.
Keyway temperatures:
I
Response
The Big Rock Point LP turbine has no dises.
5 Critical crack size and basis for the calculation:
Response
The Big Rock Point LP turbine has no discs so this calculation is not applicable.
6.
Calculated bore and keyway stress at operating design overspeed:
Response
The Big Rock Point LP turbine has no bore and rv keyways so this calculation is not applicable.
7 Calculated KIC data:
Response
Calculated KIC data and calculation methods have been previously supplied to the NRC by General Electric's Large Steam Turbine Department. These data and methods do apply to the turbine at Big Rock Point.
8.
Minimum yield strength specified for each dise:
Response
The Big Rock Point LP turbine has no discs so this specifica-tion does not apply.
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l 1
3 ITEM II Provide details of the results of any completed in-service inspection of LP turbine rotors, including areas exanined, since issuance of an operating license. For each indication detected, provide details of the location of the indiciation, its orientation, size and postulated cause.
Response
The Consumers Power Company's Big Rock Point turbine has been inspected three times (April 1964, February 1970 and March 1977). In each case the rotors and buckets were non-destructively tested using magnetic particle methods. No indi-cations have been found on the rotors.
ITEM III Provide the neninal water chemistry conditions for each LP turbine and describe any condenser inleakages or other significant changes in water chemistry to this point in its operating life.
Response
Big Rock Point has never sampled the condensed steam from the low pressure turbine. Reactor water analysis most closely approximates the chemistry of the steam flowing over the low pressure turbine. Typically observed values for the last four years of operation have been as follows:
pH 7.0 + 0.7 conductivity 0.5 "bhho/cm3 chlorides 10pp boron 0.2 ppm SiO2 0.1 ppm During the past eighteen years of operation minims 1 changes in water chemistry have been observed. The use of deep bed polishers and the quality of rav vater used for condensate makeup and condensor cooling have assisted greatly in the control of water chemistry at Big Rock Point.
ITEM IV If your plant has not been inspected, describe your proposed schedule and approach to ensure that turbine cracking does not exist in your turbine:
Response
The Big Rock Point turbine has no dises; therefore, disc cracking does not exist.
ITEM V
_If your plant has been inspected and plans to return or has returned to power with cracks or other defects, provide your proposed schedule for the next turbine inspection and the basis for this inspection schedule, including postulated defect growth rate:
Response
This does not apply to Big Rock Point because of the absense of dises.
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ITEM VI Indicate whether an analysis and evaluation regarding turbine missiles have 4
been perfonned 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:
-Response There has been no formal analysis or evaluation regarding turbine missiles. The Big Rock Point turbine is oriented in an "end on" configuration relative to the containment. This favorable orientation, combined with integral wheel construc-tion would preclude turbine missiles consideration for containment; therefore, no additional action vill be taken with respect to turbine missiles, GENERIC QUESTIONS I.
Describe what quality control and inspection procedures are used for the disc bore and keyway areas.
II.
Provice details of the General Electric repair / replacement procedures for faulty dises.
III. What immediate and long-term actions are being taken by General Electric to minimize future " water cutting" problems with turbine discs? What actions are being recommended to utilities to minimize " water cutting" of discs ?
IV.
Describe fabrication and heat treatment sequence for discs, including thermal exposure during shrinking operations.
RESPONSE TO GENERIC QUESTIONS 1
The Big Rock Point turbine has no dises; therefore, these generic questions do.
not apply.
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