ML19332A076
| ML19332A076 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 09/05/1980 |
| From: | Kay J YANKEE ATOMIC ELECTRIC CO. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19268D030 | List: |
| References | |
| WYR-80-104, NUDOCS 8009100542 | |
| Download: ML19332A076 (7) | |
Text
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o Telephone 617 36b-90ll 4
TwK 7tO-3 90-C73 9 YANKEE ATOMIC ELECTRIC COMPANY u'a-80-104 B.3.2.1 Y p,h f
20 Turnpike Road Westborough, Massachusetts 01581 e,~au x es September 5, 1980 United States Nuclear Regulatory Commission Washington, D.C.
20555 Attention:
Mr. Dennis M. Crutchfield, Chief Operating Reactors Branch #5 Division of Licensing Reference :
(a) License No. DPR-3 (Docket No. 50-29)
(b) YAEC Letter to USNRC dated August 29, 1980 (WYR 80-99)
(c) Westinghouse Steam Turbine Division Letter dated March 4,1980 from J. Schmerling, W to D. Eisenhut, NRC
Subject:
Information Related to Turbine Discs
Dear Sir:
This letter submits information related to the Yankee Rowe turbine which had inadvertently not been included in our letter transmitting the turbine disc failure analysis [ Reference (b)]. Much of this information has already been supplied in discussions with the staff in late January,1980, and responds to site specific questions. Responses to generic questions have been prepared by the W Turbine Disc Integrity Task Force and were submitted to you by Westinghouse at the request of the Task Force. These responses are contained in Reference (c).
A complete UT inspection of the keyway and disc bore areas of the low pressure rotor has been performed. Discs No.1 and 2 on both generator and governor ends have been removed. These two discs represented the most ljkely discs to show cracking due to the stress corrosion phenomenon.
The inspection showed that no detectable cracking exists in the remaining discs. A determination has been made that the rotor is suitable for satisfactory operation until the next inspection period.
The information contained in Attachment A contains proprietary information of the Westinghouse Electric Corporation. We request that this information be withheld from public disclosure. Westinghouse is preparing the necessary application for withholding this information and an affidavit to set
.8009100 5 9 2 P
'Onitdd-Stntda'NuclEtr Riguletory' Commission
.Sspttmbsr 5.-1980 Att:ntiont.Mr..Dennia M. Crutchfield, Chisf P:gn 2
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's forth the basis on which the information may be withheld. These documents will-be forwarded to you shortly.
- Very truly-yours, YANKEE ATOMIC ELECTRIC COMPANY 4
G J. A. Kay Senior Engineer Licensing JAK/kab Enclosures-1 l
l l
l E.
r Information Related to Turbine Discs Site Specific General Questions I.
Provide the following information for each LP turbine:
A.
Turbine Type - tandem compound, double exhaust ste.m turbine with shrunk on disc construction and operating at 1800 rpm. The unit-is designated by Westinghouse as a AT-4008 frame with last row blades having a nominal length of 40 inches. The design inlet 0
condition is 450 PSI throttle pressure and 460 F throttle
' temperature. There are two' moisture separa. tors with no reheat capability.
B.
Number of_ turbine operating hours - 134,468 hours0.00542 days <br />0.13 hours <br />7.738095e-4 weeks <br />1.78074e-4 months <br /> C.
Number 0; turbine trips and overspeed -
turbine trips - 191 overspeeds - 1 20% overspeed (factory test) 20 11% overspeed D.l.
Type of material including material specifications - the disc material is a Ni Cr Mo V grade of steel manufactured in accordance with Westinghouse specifications 9322 and 5875 These specifications are similar to ASTM-294-79, Class C and ASTM-A471 (vintage circa 1959) materials.
D.2.
Tensile properties data - this data is shown on Table 3 D.3 Toughness properties - Toughness testing was not required during turbine disc fabrication. Consequently this data is unavailable;
.however, additional information is supplied for disc no.1 regarding its toughness properties in Reference (b).
D.4.
Keyway temperatures - this information is contained in Tablo 4.
This is the calculated temperature two inches from the exhaust face of the disc at the bore during-full power operation.
D.5
. Calculated keyway crack size for turbine time specified in "B" above - not applicable since an inspection has been performed and no cracks exist.
D.6.
_ Critical crack size - due to the unavailability of Charpy V-notch data, a range of KIC values will be developed to determine the critical crack size for purposes of disc re-inspection. Some testing has been performed on the No. I generator end disc to determine its toughness properties. This information is contained in Reference (b).
D.7 Ratio of calculated crack to critical crack size - not applicable since an inspection has been performed and no cracks exist.
D.8.
Crack growth rate - this information'is contained in Table 4.
.D.9 Calculated bore and keyway stress at operating and design overspeed - the bore tangential stress at 1800 rpm and design overspeed (20%) are presented in Table 4.
The' values presented include stresses due to the shrink fit and centrifugal force. loads
-only.
D.10. Calculated KIC data - See Items D.3 and D.6 above.
D.ll. Minimum yield strength specified for each disc - this information is contained in Table 3 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 in31 cation detected, provide details of the location of the crack, its orientation, and size.
The HP and LP rotors were both ultrasonically inspected for cracking in the keyway and disc bore areas. The inspection encompassed all keyways on discs 3 thru 5 on the LP rotor and discs 1 thru 3 on the HP rotor.
Also, an ultrasonic 360 scan was made on the inlet and outlet side of each disc.
The inspection results are as follows:
'LP - The discs on this rotor were free of indications. The No. 1 and No. 2 discs, both generator and governor end, were removed prior to inspection, and did not require nor receive inspection. These discs have been temporarily replaced by baffling.
HP - The discs on this rotor were free of indications with the following exceptions:
The No. 1 disc, governcr end, displayed a tangential aim indication on the inlet side. The No. 2 disc, governor end, displayed a tangential aim indication at the keyway of balance
. hole No. 17 In both cases, further inspection revealed each indication ha~ no depth.
,III.
Provide the nominal Jater 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.
The nominal water chemistry conditions are shown in Table 1.
The history of water chemistry at Rowe has demonstrated the capability to operated essentially free of contaminants. Early operation of the plant
?mphasized tight. controls on phosphate addition (approximately 4-5 ppm) with a subsequent switchover to all violatile chemistry.
Presently, the
- plant operates with a continuous feed of hyorazine (approximately 2-10 ppb) and continuous blowdown. The chemistry of the steam generator water, steam, and feedwater is essentially the chemistry of pure water containing a trace of ammonia.
Condenser inleakage from Sherman pond is essentially pure water. A typical chemical analysis is given.in Table 2.
The water.is low in contaminants and is neither acid forming nor alkali forming at steam generator water temperatures.
The integrity of the Rowe condenser has been excellent. During the 19
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years of operation, only 210 tubes of the 12,495 tubes have been plugged, half of these being plugged as a precautionary measure; during the entire operating period, no evidence of denting has been observed.
Condenser leaks are generally detected and corrected at 500 spd or less and a steam generator chloride concentration of less than 1 ppm.
IV.
If your plant has not bee. inspected, describe your proposed schedule and approach to ensure that turbine cracking does not exist in your turbine.
Not applicable since Yankee Rowe has been inspected and no cracks were found.
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.
A re-inspection schedule has not been established. Westinghouse will not have a recommended time interval available until the current series of all low pressure disc inspections is completed and reviewed. This is not expected for several months. We will notify you at that time.
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.
Westinghouse is presently calculating missile probabilities and energies specifically for the Yankee Rowe machine. Results are expected later this year. This information will be factored into the SEP Topic III-4.B review scheduled for mid-1981.
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TABLE 1-TYPICAL'STEA" CEERATO*: BLOh'D91" CHE"I ST"Y AT - FULL PO'.'T" (Approxinately. 17 Steam rjou) 1.
.1960~- PRESENT (All Volatile Chemistry)
.r.
pH 3.0 - 8 5
' Cation Conductivity 0.8 -
1.'
pm59/cr.
Ammonia 0.1 - 0.2 ppm
. So3ium.
20 pp5 Chloride 30 pp5 Silica 50 pp5 Free Hydroxide.
None II.
1960 - 1968'(Phosphate Chemistry)
. pli 0.9 Conductivity 50 p,50/ce P!osp14Le 4 ppm An,onia 0.3 pp, Sodium 1 -ppm Chloride ~
0.15 ppn Silica
.1 - 2 ppe Free' Hydroxide Negative Disolved Oxygen-5 pp5 I!yirazine -
0 - 20 pp5 l
1 k
1 i.
h u
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L TA9LE 2 TYPICAL CllC*ICAL ANAT.YSIS OF S!En"X: PO."D NATER p!!
5.4 - 7.1 P
Al'<alin i ty (Frec) 0 pp-
~
Alkalinity (Bicarbonate) 9 pp lia rdne s s 10 ppm Total Dissolved Solids 25 ppm Organic Macromolecules (Fulvic and llumic Acids) 5 - 10 ppm Sodiua 3 ppe Calcium 7 ppm Magnesium 3 ppm Chloride 2 ppm Sulfate 2 ppm
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Silica 4 ppm Bicarbonate 9 ppm O
s
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