ML19305A823
| ML19305A823 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 03/13/1980 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | Harold Denton, Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| IEIN-79-37, NUDOCS 8003180408 | |
| Download: ML19305A823 (8) | |
Text
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O Wisconsin Electnc m comu 231 W. MICHIGAN, P.O. BOX 2046. MILWAUKEE WI 53231 March 13, 1980 Mr. Harold R.
Denton, Director Office of Nuclear Reactor Regulation U. S. NUCLEAR REGULATORY COMMISSION Washington, D.
C.
20555 Attention:
Mr.
D.
G. Eisenhut, Acting Director Division of Operating Reactors Gentlemen:
DOCKET NO. 50-301 INFORMATION RELATED TO TURBINE DISCS POINT BEACH NUCLEAR PLANT, UNIT 2 Your letter dated February 25, 1980, and NRC IE Informa-tion Notice No. 79-37 discussed potential problems related to the discovery of cracks in the keyway sections of Westinghouse 1800 RPM low pressure turbine discs.
Your letter requested that we consider prompt full UT inspection of the low pressure turbine rotor discs for the Point Beach Nuclear Plant, Unit 2.
We were also requested to provide responses to the requests for additional information contained in Enclosure 2 to your letter.
These responses are enclosed herewith.
As discussed in these responses, and during our meeting with members of your Staff on February 6, 1980, we have scheduled a full U'r inspection of the Point Beach Unit 2 low pressure turbine rotor discs for the Spring 1980 refueling outage.
This outage is presently scheduled to commence on either April 4 or April 11, 1980.
As presented in the enclosed material, critical keyway crack sizes, the predicted crack growth rates, and operating history of the turbine are such that the continued operation of the Unit 2 turbine, until this outage, does not present an operational or safety related concern.
We therefore intend to continue with our present plan for inspection of the Unit 2 low pressure turbine discs in April 1980.
In response to Site Specific Question I.D. and Generic Questions I through VIII, Westinghouse Electric Corporation has provided detailed information which Westinghouse believes to be proprietary.
This information, which is enclosed as gf
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w 9 8003180
Mr. Harold R.
Denton March 13, 1980 to the Site Specific Responses and as the entire response to the Generic. Questions, should be withheld from public disclosure in accordance with the provisions of 10 CFR 2.790.
In order to expedite submittal of this proprietary information, the information is attached hereto.
Under separate cover, Westinghouse Electric Corporation will submit the supporting bases, including affidavit, for this proprietary designation as required by Part 2.790.
Should you have any question? regarding this information, or should you require additional information, we would be pleased to respond.
4 Very truly yours, d E f
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t C. W.
Fay, Director Nuclear Power Department Enclosures Subscribed and sworn to before me This 13th day of March, 1980.
R.A M w D b ib-h-m Notary Public, State of Wisconsin My Commission. expires AS k, / /76
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= n ADDITIONAL INFORMATION RELATED TO TURBINE DISCS POINT BEACH NUCLEAR PLANT, UNIT 2 RESPONSES TO SITE SPECIFIC QUESTIONS I.
Provide the following information for each LP turbine:
A.
Turbine type
RESPONSE
This unit consists of one Tandem ccmpound four flow, three casing, condensing, 1800 RPM turbine utilizing 40-inch last row blades in each low pressure element.
The low pressure element is designated as a Building Block 80 (BB80).
B.
Number of hours of operation for each LP turbine at time of last turbine inspection or if not inspected, postulated
'to turbine inspection.
RESPONSE
The Point Beach Nuclear Plant (PBNP) Unit 2 low pressure tdrbine rotor discs have not been subjected to a UT inspection.
Through the end of February 1980, the Unit 2 turbine generator had been on line for a total of 59,121.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
It is anticipated that at the time of shutdown for the turbine inspection in April 1980, the total turbine operating hours will be less than 59,900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />.
C.
Number of turb'ine trips and overspeeds.
RESPONSE
A listing of the turbine trips from power and the results of overspeed testing of PBNP Unit 2 are listed in Attachment 1 to this Enclosure.
D.
For each disc:
l.
type of material including materia'l specifications 2.
tensile properties data 3.
toughness properties data including Fracture Appearance Transition Temperature and upper energy and temperature 4.
keyway temperature 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 e--=
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calculated bore and keyway stress at operating design overspeed 10.
calculated Klc data 11 minimum yield strength specified for each disc.
RESPONSE
The information requested for each disc may be found in the tables supplied as Attachment 2.
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 of the crack, its orientation, and size.
RESPONSE
To date, there have been no inservice inspection of the PBNP Unit 2 low pressure turbine rotor discs.
III.
Provide the nominal water chemistry conditions for each LP turbine and describe any condenser inleakages or other significant changes in secondary water chemistry to this point in its operating life.
Discuss the occurrence of cracks in any given turbine as related to history of secondary water chemistry in the unit.
RESPONSE
PBNP Unit 2 was placed in commercial service on October 1, 1972, using coordinated phosphate treatment for secondary water chemistry control as specified by the steam generator manufacturer, Westinghouse Electric Corporation.
During the first refueling outage, the unit was switched over to an all-volatile chemical
-control (AVT) as recommended by Wescinghouse.
The unit was returned to service in December 1974 utilizing AVT secondary water chemistry control.
The historical secondary water chemistry control has been otherwise unexceptional.
Since Unit 2 turbine rotor discs will not be inspected until April 1980, obviously no cracks have been identified in this turbine.
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 Point Beach Unit 2 low pressure turbine rotor discs will be inspected - by 'destinghouse Electric Corporation using UT techniques
l l
l !
l discussed in the turbine disc inspection report submitted with our letter dated January 30, 1980, in the Point Beach Unit 1 Docket 50-266.
The Unit 2 turbine discs, except for disc #6 which is not inspectable, will be inspected from both the inlet and outlet sideo.
V.
If your plant has been inspected and plans to return or has returned to power with cracks, provide your proposed schedule for the next turbine inspection and the basis for this inspection schedule.
RESPONSE
Point Beach Unit 2 will be inspected in April 1980.
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.
RESPONSE
As discussed in Section 14.1.13 of the Point Beach Nuclear Plant Final Facility Description and Safety Analysis Report and Westinghouse Topical Report WCAP-7525-L, dated June 1970, the likelihood and consequences of a turbine overspeed resulting in a turbine missile have been analyzed and evaluated.
A reevalua-tion of the likelihood and consequence of a turbir.e missile will be performed upon receipt of the revisions to previously reported missile generation probabilities and missile energies presently being developed by Westinghouse.
We expect to receive this information from Westinghouse by July 31, 1980, and will submit a report of our turbine missile reevaluation as soon thereafter as prard eable.
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ATTAcE4Ehr 1 Pega 1 of 3 NUMBER OF TRIP FROM AT POWER - UilIT 2
% or FMe Maximum Power Overspeed Date Cause Level If Known 8-4-72 Turbine Trip - Loss of Feed Pump 17 FMe 8-18-72 Reactor Trip - NIS Int. Range 8-31-72 Loss of AC - Reactor Trip Test 20%
12-7-72 Turbine Trip - Loss of Feed Pump 20%
12-7-72 Reactor Trip - Lolo S/G Level Low Power 3-9-73 Trip Unit for Overspeed Test 150 FMe 2003 RPM 3-10-73 Turbine Trip - Loss of Feed Pump 250 MWe 3-14-73 Reactor Trip - Lolo Steam Line 475 FMe Pressure 3-14-73 Manual Trip - Feedwater Heater Noise Low Power
~3-24-73 Trip Unit for Overspeed Test 150 FMe 2012 RPM j
3-26-73 Reactor Trip - Lolo Steam Line 475 FMe Pressure 3-30-73 Reactor Trip - Instrument Power 375 MWe Failure j
3-30-73 Trip Unit for Overspeed Test 350 MWe 2183 RPM 1
4-8-73 Turbino Trip - MSSV Closure 480 MWe 5-30-73 Reactor Trip - Low Flow While 480 MWe Bringing VCT Online l
6-19-73 Reactor Trip - Instrument Power Fail-480 MWe ure.
12-15-73 Reactor Trip - Equipment Failure 495 FMe 12-22-74 Trip Unit for Overspeed Test 430 he 2215 RPM 2-11-75 Turbine Trip - Lo Vacuum 100%
6-22-75 W Test Low Power 1-14-76
~ Manual Trip - Circulating Water 75%
Problem 4-8-76 Reactor Trip - Loss of 4.16KV Power 100%
'9-3-76 Reactor Trip - Trip 3reaker Opened 100%
While Testing
ATTACEMENT 1 Pcga 2 of.3 (NUMBER OF TRIP'FROM AT POWER - UNIT 2 Continued)
% or MWe Maximum Power Overspeed Date Cause Level If Known 1-12-77 Turbine Trip - DC Power Spikes 100%
6-28-77 Turbine Trip - DC Power Spikes 100%
7-7-77 Reactor Trip - Loss ~ of A01 A02 100%
1-10-78
-Turbine Trip - Lo Vacuum 100%
11-21-79 Reactor Trip - Instrument Power 100%
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ATTACHMENT 1 Ptga 3 of 3 OVERSPEED TESTING - UNIT 2 Date Reason / Type Results 8-2-72 Overspeed Tests Mechanical 1880, 1877, 1878 Aux. Gov.
- 1851, 851 IE0pS 1844, 1844, 1844 8-2-72 Overspeed Tests 1872, 1869, 1870 8-3-72 Overspeed Tests 1827, 1826, 1825 8-3-72 Overspeed Tests Mechanical 1826, 1822 Aux. Gov.
1850 8-3-72 Overspeed Tests Mechanical 1856, 1855, 1855 Aux. Gov.
1833 3-9-73 Unit Tripped from 150 MWe to Check Overspeed 2003 Overshoot 3-24-73 Jnit Tripped from 150 MWe to Check Overspeed 2012 Overshoot 3-30-73 Unit Tripped from 350 FMe to Check Overspeed 2183 Overshoot 2-21-74 Overspeed Tests 1866, 1866 2-26-74 Increased One Flat 1887, 1886, 1886 2-27-74 Unit Tripped From 430 MWe to Check Overspeed 2215 3-27-76 Overspeed Tests 1878, 1881, 1879 l-2-77 Overspeed Tests 1879, 1880, 1879 4-19-78 Overspeed Tests 1880, 1880, 1878 4-13-79 Overspeed Tests 1880, 1881, 1879
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