ML19305C229
| ML19305C229 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 03/19/1980 |
| From: | Burstein S WISCONSIN ELECTRIC POWER CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8003260372 | |
| Download: ML19305C229 (24) | |
Text
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Attachment A Cuntains PROPRlETARY Znformation In Accordance With 10 CFR 2.790 Wisconsin Electnc ecura coursur 231 W. MICHIGAN, P.O. BOX 2046. MILWAUKEE. WI 53201 March 19,1980 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 N0. 50-266 INFORMATION RELATED TO TURBINE DISCS POINT BEACH NUCLEAR PLANT UNIT 1 In your letter dated February 25, 1980, you requested that we provide responses to a series of site specific and generic questions regarding the safety significance of keyway cracking observed in several low pressure turbine rotor discs, including Point Beach Nuclear Plant Unit 1.
This information is provided in the enclosures to this letter.
Your letter also referenced an earlier letter, dated December 27 ~, 1979, that had requested other additional information.
Our respanse to that request was provided with our letter dated January 30, 1980.
A portion of the site specific responses provided herewith contains information which is proprietary to the Westinghouse Electric Corporation.
This information is contained in Appendix A and contains the responses to site specific question I.D.
In conformance with the requirements of 10 CFR Section 2.790, as amended, of the Commission's regulations, we are enclosing herewith an application for withholding this proprietary material from public disclosure and an affidavit in support of that application.
The affidavit sets forth the basis on which the infonnation may be withheld from public disclosure by the Ccmission.
Correspondence with respect to the affidavit or application for with-holding should reference AW-80-10 and should be addressed to Mr. R. Williamson, Manager, Customer Order Engineering, Westinghouse Electric Corporation, Steam Turbine Divisions Lester Brancn, Box 9175, Philadelphia, PA.19113.
Very truly yours, t
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I Sol Burstein Exec tive Vice President 90W*f h Woe < fp gqz P
800320 9
AW-80-10 March 14, 1980 Darrell G. Eisenhut i
Division of Operating Reactors Office of Nuclear Reactor Regulation US Nuclear Regulatory Cannission Washington DC 20555 APPLICATION FOR WITHHOLDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE
Subject:
Point Beach #1 Docket #50-266 Information in Response to NRC Request for Information of Feb ruary 25, 1980, Relative to Low Pressure Turbine Disc Integrity.
Reference:
Appendix A letter from Sol Burnstein to Eisenhut, dated 3/17/80
Dear Mr. Eisenhut:
This application for withholding is subtitted by Westinghouse Electric Corporation (" Westinghouse") pursuant to the provisions of paragraph (b)(1) of Section 2.790 of the Commission's regulations. Withholding from public disclosure is requested with respect to the subject information which is further identified in the af fidavit accompanying this application.
The undersigned has reviewed the information sought to be withheld and is authorized to apply for its withholding on behalf of Westinghouse, STG-TOD.
The affidavit accompanying this application sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in par graph (b)(4) of Section 2.790 of the Commission's regulations.
Accordind y, it is respectfully requested that the subject information which l
is proprietary to Westinghouse and which is further identified in the affi-davit be withheld from public disclosure in accordance with 10CFR Section 2.790 of the Commission's regulations.
Correspondence with respect
- .o this application for withholding or the accom-panying af fidavit should be addressed to the undersigned.
Very truly yours, a
s N5E $.Y N &
R. Williamson, Manager Customer Order Engineering Westinghouse Electric Corporation I
Raf: AW-80-10 AFFIDAVIT COMMONWEALTH OF PENNSYLVANIA COUNTY OF DELAWARE:
Before me, the undersigned authority, personally appeared Robert Williamson, who, being by me duly sworn according to law, deposes and says that he is authorized to execute this Affidavit on behalf of Westinghouse Electric Corporation (" Westinghouse") and that the averments of fact set forth in this Affidavit are true and correct to the best of his knowledge, information, and belief:
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Robert Williamson, Manager Customer Order Engineering Ewern ts.a.M s*f:::ibed b(cre me uus j..h...cr/ of.I.WM9..Yt..
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. HENRY E. SQUlLLACE Notary Pubile. Wrple Two.. Delsmare Co My CcmmisGa Espires Oct. 18.1980 l
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(1) I am Manager, Customer Order Engineering in the Steam Turbine Generator Technical Operations Division of Westinghouse Electric Corporation and as such, I have been specifically delegatec the function of reviewing the proprietary information sought to be withheld from public disclosure in connection with nuclear power plant licensing, and am authorized to apply for its withholding on behalf of the Westinghouse Power Generation Divisions.
(2) I am making this Affidavit in conformance with the provisions of 10 CFR Section 2.790 of the Commission's regulations and in conjunction with the Westinghouse application for withholding accompanying this Affidavit.
(3)
I have personal knowledge of the criteria and procedures utilized by Westinghouse Power Generation Divisions in designating informa-tion as a trade secret, privileged or as confidential commercial or financial information.
(4)
Pursuant to the provisions of paragraph (b)(4) of Section 2.790 of the Commission's regulations, the following is furnished for con-sideration by the Commission in determining whether the information sought to be withheld from public disclosure should be withheld.
(1)
The information sought to be withheld from public disclosure is owned and has been held in confidence by Westinghouse.
(ii)
The information is of a type customarily held in confidence by Westinghouse and not customarily disclosed to the pub-lic. Westinghouse has a rational basis for determining the types of information customarily held in confidence by it and, in that connection, utilizes a system to determine when and whether to hold certain types of information in confi-dence. The application of that system and the substance of that system constitutes Westinghouse policy and provides the rational basis required.
)
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Under that system, information is held in confidence if it falls in one or more of several types, the release of which might result in the loss of an existing or potential com-Petitive advantage, as follows:
(a) The information reveals the distinguishing aspects of a process (or component, structure, tool, method, etc.)
where prevention of its use by any of Westinghouse's competitors without license from Westinghouse consti-tutes a competitive economic advantage over other companies.
(b)
It consists of supporting data, including test data, relative to a process (or component, structure, tool, method, etc.), the application of which data secures a competitive economic advantage, e.g.,
by optimization or improved marketability.
(c)
Its use by a competitor would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing a similar product.
(d)
It reveals cost or price information, production capac-ities, budget levels, or commercial strategies of West-inghouse, its customers or suppliers.
(e)
It reveals aspects of past, present, or future Westing-house or customer funded development plans and programs of potential commercial value to Westinghouse.
( f)
It contains patentable ideas, for wnich patent protec-tion may be desirable.
(g) It is not the property of Westinghouse, but must be treated as proprietary by Westinghouse according to agreements with the owner.
(h) Public disclosure of this information would allcw un-fair and untruthful judgments on the performance and reliability of Westinghouse equipment components and improper comparison with similar components made by competitors.
There are sound policy reasons behind the Westinghouse system which include the following:
(a) The use of such information by Westinghouse gives West-inghouse a competitive advantage over its competitors.
It is, therefore, withheld from disclosure to protect the Westinghouse competitive position.
(b) It is information which is marketable in many ways.
The extent to which such information is available to competitors diminishes the Westinghouse ability to sell products and services involving the use of the information.
(c) Use by cur competitor would put Westinghouse at a com-petitive disadvantage by reducing his expenditure of resources at our expense.
(d) Each component of proprietary information pertinent to a particular competitive advantage is potentially as valuable as the total competitive advantage. If ecm-petitors acquire components of proprietary information, any one component may be the key to the entire puzzle, l
thereby depriving Westinghouse of a competitive advantage.
i l
(e) Unrestricted disclosure would jeopardize the position of prominence of Westinghouse in the world market, and thereby give a market advantage to the competition in these countries.
( f) The Westinghouse capacity to invest corporate assets in research and development depends upon the success in obtaining and maintaining a competitive advantage.
('iii) The information is being transmitted to the Commission in confidence and, under the provisions of 10 CFR Sec-tion 2 790, it is to be received in confidence by the Commission.
(iv)
The information is not available in public sources to the best of our knowledge and belief.
(v)
The proprietary information sought to be withheld in this submittal is that which is appropriately marked in Appen-dix A to letter from S. Burnstein to Eisenhut, dated March 17, 1980 concerning infor-mation in response to NRC request for information of February 25, 1980, relative to low pressure turbine disc integrity.
The information enables Westinghouse to:
(a) Develop test inputs and procedures to satisfactorily verify the design of Westinghouse supplied equipment.
(b) Assist its customers to obtain licenses.
Further, the information has substantial commerc.a1 value as follows.
(a) Westinghouse can sell the use of this information to Customers.
(b) Westinghouse uses the information to verify the design of equipment which is sold to customers.
(c)
Westinghouse can sell services based upon the exper-ience gained and the test equipment and methods developed.
Public disclosure of this information is likely to cause substantial harm to the competitive position of Westinghouse because it would enhance the ability of competitors to design, manufacture, verify, and sell electrical eluipment for commercial turbine-generators without commensurate expenses. Also, public disclosure of the information would enable others having the same or similar equipment to use the information to meet NRC requirements for licensing documentation without purchasing the right to use the information.
The development of the equipment described in part by the information is the result of many years of development by Westinghouse and the expenditure of a considerable sum of money.
This could only be duplicated by a competitor if he were to invest similar sums of money and provided he had the appro-priate talent available and could somehow obtain the requi-site experience.
Further the deponent sayeth not.
ADDITIONAL INFORMATION RELATED TO TURBINE DISCS POINT BEACH NUCLEAR PLANT, UNIT 1 RESPONSES TO SITE SPECIFIC QUESTIONS I.
Provide the following information for each LP turbine:
A.
Turbine type
RESPONSE
This unit consists of one Tandem compound 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 cf last turbine inspection or, if not inspected, postulated to turbine inspection.
RESPONSE
The Point Beach Nuclear Plant (PBNP) Unit 1 low pressure turbine rotor discs were inspected between October 22 and November 2, 1979.
At the time of this inspection, the unit had compiled 63,928 turbine operating hours.
C.
Number of turbine trips and overspeeds.
RESPONSE
A listing of the turbine trips from power and the results of overspeed testing of PBNP Unit 1 are listed in Attachment 1 to this Enclosure.
D.
For each disc:
1.
type of material including material specifications 2.
tensile properties data 3.
tougnness properties data including Fracture Appearance Transition Temperature and upper energy and temperature 4.
keywcy temperat' ire 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 8.
Orack growth rate 9.
calculated bore and keyway stress at operating design overspeed
10.
calculated K c data l
11.
minimum yield strength specified for each disc.
RESPONSE
The information requested for each disc may be found in the tables supplied as Appendix A (Proprietary) and Appendix B.
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
The results of the Fall 1979 inservice inspection of the PBNP Unit 1 turbine rotor discs were reported to the NRC in Licensee's letter dated January 30, 1980.
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 1 was placed in commercial service on December 21, 1970, using coordinated phosphate treatment for secondary water chemistry control as specified by the steam generator manufacturer, Westinghouse Electric Corporation.
On September 9, 1974, the unit was switched over to an all-volatile chemical control (AVT) as recommended by Westinghouse.
The historical secondary chemistry control has been otherwise unexceptional.
It is not known at what point in the turbine's operating history the recently discovered cracking occurred.
Whether or not water chemistry was or is a factor in the occurrence of the cracks may possibly become apparent as a result of monitoring procedures for currently sound, in-service discs.
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 PBNP Unit i low pressure turbine rotor discs were inspected during the October-November 1979 refueling outage.
h
i V.
If your plant has been inspected and plans to return or has
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returned to power with cracks, provide your proposed schedule for the next turbine inspection and the basis for this inspection. schedule.
RESPONSE
As discussed in our letter to Mr. Denton dated January 30, 1980, we are planning to. reinspect the Unit 1 discs during the Fall 1980 outage to determine whether there has been a change in the condition of the LP turbine rotors.
The basis for our continued operation was also discussed in that letter and wi th the NRC Staff members at a meeting in Bethesda on February 6, 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 reevaluation of the likelihood and consequence of a turbine 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 practicable.
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'l RESPONSES TO GENERIC QUESTIONS sI.
Describe what quality control and inspection procedures are used for the disc bore and keyways.
RESPONSE
Chemical analyses are made from each heat of steel.
During manu-facture, mechnical tests are made from the disc bore region.
These include tensile and Charpy v-notch impact tests.
Each disc bore region is subject to ultrasonic and magnetic particle inspections.
On later units, the disc keyways are inspected after machining, using liquid penetrant techniques.
For in-service inspection two ultrasonic techniques, namely the tangential aim and radial aim scans, have been developed to detect and determine the depth of disc keyway and bore cracks.
The in-service ultrasonic inspection does not require unshrinking discs from the rotor.
The tangential aim scan is used to locate cracks.
The technique requires sound energy to be coupled and directed tangentially towards the keyway from a precalculated position on the hub.
This is accomplished by means of a compound angled plexiglass wedge.
The wedge is machined to provide a contoured face which makes complete contact with the disc hub, while aiming the sound energy at the disc bore / keyway.
Crack indications occurring in the vicinity of the keyway apex and at the bore will reflect the sound energy.
The tangential aim scan is performed both in the clockwise and counterclockwise directions to permit locating crack indications with respect to the keyway apex.
A radf al aim technique is used to confirm cracks located by the tangential aim scan.
The technique is also used to determine the crack' depth by comparing the time lapsed in obtaining a ultrasonic reflection from the crack with the time to obtain a reflection from the keyway or bore.
II.
Provide details of the Westinghouse repair / replacement
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procedures for faulty discs.
RESPONSE
When cracks are. found by an inservice inspection, their severity is evaluated by means of an allowable life calculation.
The allowable life is _ relatable to the time required for the crack to grow to critical size for fracture.
Based upon the results j
of this calculation, the following actions may be taken:
A.
If the af fected disc has a calculated 211:wable life much graater than zero, a reinspection of ne cisc is recommended l
at approximately one-half of the allowable life.
M M
5.
If the affected disc has an allowable life less than or close to zero, one or more of the following may be employed:
1.
The affected disc is removed by " machining", and is replaced with a collar and pressure drop baffle.
2.
Upstream keyways may be drilled oversize to remove cracks after the downstream disc is removed.
3.
The affected disc may be replaced.
This requires unstacking and restacking several discs on the rotor.
III.A.
What immediate and long term actions are being taken by Westinghouse to minimize future stress corrosion problems with turbine discs?
RESPONSE
Westinghouse has advised the following short range actions are being taken:
A.
Those discs which have been observed to be most susceptible to stress corrosion cracking are being redesigned.
The new designs will achieve lower bore stresses and utilize lower yield strength material.
These changes will increase the margin against stress corrosion cracking.
B.
Designs that will eliminate spacers and bore keyways are being explored.
The following long range solutions are being examined:
A.
Bore Heatina - Ways and means to keep the disc keyways dry are being explored.
B.
Sealing - Ways of sealing the hub and bore from the steam environment are being studied.
l C.
Coatings - Another method of sealing is to apply a protective l
coating.
Westinghouse is continuing to experiment with l
different sealings, but extensive work is stirl required to develop processes for their application and to demonstrate their benefits.
i D.
Partial Integral Rotors - Since one piece forgings cannot be precured at enis time, Westinghouse is exploring the possibilities of partial integral rotors where the first two er three discs are made a part of the shaft.
Only the last few discs will have to be shrunk on.
E.
Integral Roters - A welded rotor design is being evaluated as a r.eans to produce an integral rotor.
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III.B.
What actions are being recommended to utilities to minimize stress corrosion cracking?
RESPONSE
Westinghouse has developed recommended limits for steam purity.
When these limits are exceeded, corrective actions should be taken.
IV.A.
Identify the impurities known to cause cracking in the low pressure turbines, and their sources.
RESPONSE
The time of occurrence of the cracks, which have been identified in low pressure turbine discs, is not known.
Information regarding inpurities, and their sources, which may be a contri-buting factor to disc cracking, is presently being collected; additional information could become available from monitoring of currently sound discs.
The main chemical species known to cause or contribute to stress corrosion of steam turbine materials in steam environments are sodium hydroxide, sodium chloride, and sodium sulfate.
IV.B.
Discuss the relationship between steam generator chemistry and steam chemistry relative to the introduction of corrosive impurities into the turbine, including phosphate, AVT, and BWR chemistry.
RESPONSE
Analyses of material within LP disc cracks from PhG1 units shows the presence of Na, K, Ca, Si, Cl, OH, and C together with Fe, Co, V, Al and Ni ions.
.In PWR units with recirculating steam generators, the total carry-
cVer of nonvolatile discolved solids, such as NaOH and NCCl depend -
mainly on the mechanical carry-over.
However, where ammonia is used for pH control, such as with the all volatile water treatment, carry-over of anions may increase due to a formation of volatile ammonium salts.
l In the PWR units with once-thrcugh steam generators, the high pressure turbine steam purity is similar to the feedwater purity.
Most impurities entering the steam generator are carried directly into the turbine.
l l
The published information en BWR systems indicates the concentra-tion of oxygen in the steam is in the rance of 10 to 30 ppm.
With respect to other elements, however, it is'likely that high
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steam purity standards will be maintained for control of radio-activity.
To achieve this, BWR reactor water is generally double demineralized.
IV.C.
Discuss the mechanism of deposition of these impurities that can lead to their concentration in certain areas of keyways and bores.
RESPONSE
The impurities from steam can get into shrunk-on disc bores and keyways in several possible ways:
1.
After deposition in the steam path during operation, corrodents can wash into disc keyways.during layup due to moisture condensation.
2.
In the wet steam regions, the noisture can dry on hot metal surfaces.
3.
As long as the disc retains its shrink fit, Westinghouse is not aware of a mechanism which can concentrate impurities on the bore.
v.
What role does the reflux action in the steam secaration
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portion of the stemn generator have on scrubbing corrosive impurities from the steam?
RESPONSE
Two modes of transport of corrosive impurities from the steam generator to.the turbine are mechanical entrainment and volatility.
The non-volatile chemical specie's are transported by mechanical
~
entrainment which is normally expected to be small.
The steam generator scrubbing equipment has minimum effectiveness in preventing the transport of volatile impurities, such as ammonium chloride, to the turbine.
The concentration of volatile
-impurities in turbine steam is determined by their concentration in the steam generator bulk water and their specific volatility coefficient which differs with'each species.
VI.
To what extent can the buildup of corrosive impurities in
'the-LP turbine be alleviated?
What would be the effects of the following action:
A.
Pumping moisture separator condensate to condenser?
RESPONSE
Westinghouse has advised that pumping moisture separator condensate to the condenser would be beneficial in uni:s with cendensate
. polishing.
In units without condensate polishing, there will be no effect.
B.
Periodically moving (the) point of condensation to prevent localized buildup of corrosive impurities.
RESPONSE
Westinghouse has advised that conceptually, dilution of these contaminants by increased levels of moisture and their subsequent transport to the condensate system could substantially reduce the buildup of contaminants.
However, the effectiveness of this technique and the means for successful control of the local environment of particular turbine parts must be developed and experimentally verified.
Several of the less volatile active corrodents, such as sodium chloride and sodium sulphate, precipitate as concentrated liquid solutions in a region slightly above the equilibrium saturated vapor line of pure water.
This region occurs locally within a given stage during normal operation and migrates toward the turbine exhaust as load reduces.
Control of the zone can be affected by changes in load and moisture separator reheater (MSR) outlet temperature.
VII.
Describe fabrication and heat treatment sequence for discs, including thermal exposure during shrinking operation.
RESPONSE
The typical sequence for prcducing a disc forging includes the following operations, not aim of which are necessarily applicable to any given disc.
A.
Melting and Casting of Ingot - Most discs manufactured since the early 1960s are made using basic electric furnace steel
+:hich is vacuum stream degassed or vacuum-carbon-deoxidized.
B.
Forging - The ingot is heated to forging temperature, block forged and cut into two to four pieces from which the individual l
disc forgings are made, l
l C.
Preliminary Heat Treatment - This step consists of austenitizing and tempering the forging to promote structure uniformity,
, grain refinment, and good machineability, i
L C.
Preliminary Machining - The forging is machined to the disc Contour.
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. E.
Preliminary Ultrasonic Insoection - Typically, the supplier makes a partial ultrasonic inspection of the forging to assure that the quality warrants continued manufacturing effort.
F.
Heat Treatment for Properties - The forging is austenitized and tempered at appropriate temperatures to achieve the desired mechanical properties.
Cooling from the austenitizing treatment is achieved by water quenching.
After tempering, the forging is cooled in the furnace at a controlled rate.
G.
Mechanical Properties - Tensile properties are tested to determine if the required strength level has been achieved.
Since about 1960, Charpy v-notch impact tests are made on each forging.
H.
NDE Inspection - The forgings are rough machined to the Westinghouse drawing requirements and an ultrasonic inspection of the flat surfaces of the hub, web, and rim of the disc is. performed.
I.
Stress Relief - This treatment is required when a significant amount of metal is machined off of the forging after it has been heat treated for properties.
The stress relief treatment is 50-100*F below the tempering temperature.
Cooling is accomplished by a controlled furnace cool.
J.
Mechanical Properties - When a stress' relief is used, the mechanical properties are tested after the stress relief treatment.
(Reference Step G)
K.
Dimensional Check - The forging is machined to a clean surface, the balance of test prolongations are removed, and the dimensions checked.
The forging is then shipped to Westinghouse for final machining and assembly onto the rotor.
L.
_ NDE Inscection - A fluorescent magnetic particle inspection is performed after finish machining.
(This inspection was not applied during the early 1970s.)
M.
Shrinking Discs on the Rotor Shaft - The assembly operation consists of four parts; namely, preparation of the shaf t, preparation of the discs, assembly of the rotor and pinning of the discs to the shaft.
1.
Preparation of the Shaf t - Af ter final shaf t machining and inspections are complete, the shaft is cleaned with degreaser and dry lint-free cloths, and is mounted in a vertical position.
The surface of the rotor that will be in contact with the disc is coated with lubricant.
1 2.
Precaratica :f the isc - Af ter final machinin and inspect:Ons are cc 9 ece, the disc surfaces and blades are cleaned to remove foreign material.
Prior to 4
heating for asscably, the disc bore diameter is measured and compared to that of the drawing to assure a correct shrink fit.
The disc is placed on an assembly fixture, leveled and loaded into a furnace which is at 300'F or less.
3.
Assembly of the Rotor - The disc is slowly heated to the required shrink tamperature between 600 and 750*F.
When the shrink temperature is reached, the disc is removed from the furnace and lowered onto the shaft.
4.
Axial Aligning and Pinning of Discs - Liners are placed at the exhaust face of each disc to assure the proper axial location.
The keyways are then drilled, reamed and honed.
Since the early 1970s, a penetrant inspection is performed in the keyway prior to inserting the key.
VIII.
Discuss the effect of any local residual stresses on the cracking mechanism.
RESPONSE
Depending on their nature and magnitude, residual surface stresses can have an effect on crack initiation.
Proper control exercised in the selection of machining parameters results in compressive stresses, which are usually beneficial.
At an apex of the keyway, the residual stresses may be influenced by local yielding as a result of the stress concentrating action of the keyway.
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1 Pago 1 of 4 i
2.
NUMBER OF TRIPS AT POWER.
UNIT 1
% or MWe Maximum Power Overspeed Date Cause Level If Known j
11-5-70 Breaker Problem 40 MWe 11-5-70 Breaker Problem 35 MWe 11-6-70 Reactor Trip - LoLo S/G Level 30 MWe 11-7-70 Turbine Trip Loss of Feed Pump Low Power 11-8-70 Manual Trip - Governor Valve 100 MWe Problems 11-10-70 Turbine Trip - Breaker Lockout 35%
11-22-70 Testing - Transfonner Transfer.
40%
11-22-70 Testing - Load Rejection 50%
11-29-70 Testing - Turbine Trip 360 MWe 12-4-70 Turbine Trip - Breaker Lockout 422 MWe Overspeed 12-5-70 Turbine Trip - Solenoid Failure 50 MWe 12-6-70 Testing - Open Output Bkr.
70%
2190 RPM 12-8-70 Trip Unit for Overspeed Test 445 MWe 2250 RPM 12-19-70 Reactor Trip - Lolo W/G Level 35%
l-8-71
}[ Caused Trip, Working on IEOPS 425 MWe 1-9-71 Trip Unit for Overspeed Test 351 MWe 2206 RPM l-27-71 Reactor Trip - Lo Feed Flow 480 MWe 1-28-71 Turbine Trip - IEOPS Suspected 480 MWe 1-29-71 Trip Unit for Overspeed Test 351 MWe 2216 RPM 2-3-71 Turbine Trip - IEOPS Suspected 90%
2-4-71 Turbine Trip - IEOPS Failure 470 MWe 2-4-71 Turbine Trip - Autostop 011 Low 470 MWe 2-9-71 Reactor Trip - MESV Closure 400 MWe i
5-1-71 Tripped Output Bkr. - Autostop 410 MWe i
011 Low 5-1-71 Trip Unit for Overspeed Test 404 VWe 2316 RPM
g Pago 2 of 4 2.
(NUMBER OF TRIPS AT POWER - UNIT 1 Continued)
% or MWe Maximum Power Overspeed Date Cause Level If Known 7-2-71 W Worker Caused Trip 480 MWe 8-29-71 Reactor Trip - Dropped Rods 480 MWe 12-3-71 Trip Unit for Overspeed Test 410 MWe 2243 RPM l-3-72 Reactor Trip - Faulty Anal. Testing 480 MWe 1-13-72 Trip Unit for Overspeed Test 511 MWe 2340 RPM Instrument 4-21-72 Reactor Trip - Power Failure 100%
9-11-72 Reactor Trip - Hi Pressurized 100%
Pressure 5-18-73 Trip for Test 72%
7-2-73 Technician Caused Trip 500 MWe 8-11-73 Reactor Trip - Stop Valve Closure 100%
l-11-74 Reactor Trip - Instrument Power 100%
Failure 1-18-74 Reactor Trip - Instrument Power 80%
Failure 2-3-74 Manual Trip - Rod Problems 55%
8-2-74 Trip for Overspeed Test 406 MWe 2150 RPM 9-25-74 Reactor Trip - Faulty Testing 99%
10-4-74 Trip for Overspeed Test 430 MWe 2193 RPM 2-27-75 Manual Trip - S/G Tube Failure 25%
4-5-75 Trip for W Test 5%
11-16-75 Turbine Trip - Instrument Power 100%
Failure l-10-76 Reactor Trip - Steam Line Lolo 470 MWe Press "B" 2-21-77 Manual Trip - Rods Oropped After Runback l
4-5-77 Reactor Trip - Dip in AG Busses 100%
l l-7-78 Turbine Trip - M:557 Cicsure 100%
2-9-78 Turbine Trip - Breaker Lockcut 100%
4-2-78 Turbine Trip - MSSV Clcsure 100%
N 3.
OVERSPEED TESTING - UNIT 1 Date Reason / Type Results 11-8-70 Check Overspeed 12-6-70 Unit Tripped From 70% for Overspeed Test 2190 12-18-70 Unit Tripped from 445 We for Overspeed Test 2259 l-3-71 Tested IEOPS 1840 Reference 1850 Turbine Shaft 1-3-71 Tested IEOPS 1835 Reference 1848 Turbine Shaft 1-5-71 Overspeed Tests, All Trips by IEOPS 1858, 1861, 1865 1-8-71 IEOPS 1881 1-8-71 IEOPS 1877 1-9-71 Unit Trip from 351 We for Overshoot Test 2206 Overshoot 1-12-71 IEOPS 1843 Reference 1838 Digital
'l-12-71 1844 Reference 1840 Digital 1-12-71 Mechanical Overspeed 1844, 1843 1-29-71 Unit Tripped from 351 We to Check Overspeed 2216 Overshoot 5-1-71 Unit Tripped from 470 We to Check Overspeed 2274 Overshoot 5-1-71 Overspeed Tests on IEOPS 1886, 1885, 1886 Mechanical 1902 12-3-71 Unit Tripped from 410 We to Check Overspeed 2243 (IEOPS Testing 102.5%)
1.54" Abs 1-15-72 Overspeed Test 1841, 1841 1-19-72 Unit Tripped from 511 We to Check Overspeed 2340 3-6-73 Overspeed Test 1835, 1836, 1831
1FUsK-J N
~
- 3. (OVERSPEED TESTING - Unit 1 Continued)
Date Reason / Type Results 6-8-74 Overspeed Test 1870, 1870, 1872 8-2-74 Unit Tripped from 406 MWe to Check Overspeed 2150 Overshoot 10-4-74 Unit Tripped from 430 MWe to Check Overspeed 2193 Overshoot 1-9-76 Overspeed Test 1874, 1370, 1869 l-25-76 Overspeed Test 1873, 1866, 1867 5-77 Overspeed Test 1871, 1871, 1869 10-15-78 Overspeed Test 1864, 1863, 1862 12-1-79 Overspeed Gov. Raised One Flat Prior to Test 1885, 1884, 1883 W
e D
.r y
.-c--
l'Ulill 11Alli NtM.LI AR 81ANI lifill I e
Appen.11x 11 ADDil!0NAL IN10kfiAll0N-TURtilNE DISC LP-1 GOVERNOR END LP-GENERATOR END LP-2 GOVERNOR END LP-2 GENGiATOR END
- ulWiisilk 1
2 3
4 5
6 1
2 3
4 5
6 1
2 3
4 5
6 1
2 3
4 5
6 ti.l.-Hatestal T u Meterial Type for all Discs is Ni-Cr-Mo-V Alloy Steel Similar to ASTMA-471 U.2.-Tensile b,c.e
. Huh.
Vield Strength-KSI
- Ultuute Tensile Strength-KS!
Llungstlure - %
kaustlen Area - %
ellll:
ile~ld Strength-KSI Ulti ute lensile Strunyth-SKI-
'Llongation - %
kedsction Area-:
f.3. - Toughness 6
9 hh. *F UA
- Room Temp lupact W
ft.LLs.
Upper Shelf impact It.Lbs.
6 3
bpper Sr. elf g
Te;p. -
F-RIH:
b ch TUI
- r r--~ '
Ruou Temp. lupact 7M thltinpact h
~
0 r
+
it.tt.s.
b Opper S 41f Tes.p.
- t u.4. p.cf.ay
_ly. p.
- f 4.....
[
~
l 11)lNi I;IIJ.ll ("Illi AR l'1 Afd 121I I ADull!OriAL INiulalAT10N-IURUINL DISC
-Appendix %
LP-1 COVERA 0R END LP-1 GEhERATOR END LP-2 GOVERNOR END LP.2 GENERATOR ENO IilTC.m.tdiR I
2 3
4 5
6 1
2 3
4 5
6 1
2 3
4 5
6 1
2 3
4 5
6 0.5. Calculated Crack Size b,c.e At 63.924 Hours o - in.
p D.'d. Ef fective Critic.el Crack Size 16,00 Hi>tt - in.
Y t
tiesign OverspecJ D. 7. fu t to DS to 06 5s y,<,
u d. f reck G., th (Q
xare
'J]/K ~ iniist x Tu-t PS t
CIM p.'J. Calu l ted S
livre 4 tcyway C
Stress l,' ors Stress - KS!
M e It.00 aiPii f
v i32.
eep.ay Stress NOTE:
Keyway Stress is not used directly in the calculation of effective critical crack size and is not available. The Bore Stress is used together with a Keyway shape factor. Q. to calculate critical crack size.
D.10. KIC Calculated -KSI/if b,c.e hub:
HIN.
U.11. Hin. Vield Strength Specified Y.S. hub - KSI heI 2-e
.