ML19338D093
| ML19338D093 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 09/15/1980 |
| From: | Finfrock I JERSEY CENTRAL POWER & LIGHT CO. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-04.B, TASK-3-4.B, TASK-RR NUDOCS 8009190421 | |
| Download: ML19338D093 (13) | |
Text
G f
Jersey Central Power & Light Company 3 m.[ ff ()
gg.
Madison Avenue at Punch Bowl Road Mornstown, New Jersey 07960 (201)455-8200 September 15, 1980 Mr. Dennis M. Crutchfield, Chief Operating Reactors Branch #5 Division of Licencing Uni *ad S tates Nucl ear Regul atory Cornission W as'T i ng to n, D. C.
20555
Dear '4r. 'cutchfield:
Subject:
Oyster ^ reek Nuclear Generating Station Dxket No. 50-219 "urbine Disc Integrity
)
Your letter of June 11, 1980 requested that we prov i de i n f ormation concerning the integrity of turbine discs at the Oyster Creek Nuclear Generating 3 h3 r i on and address its safety significance.
Attachmeit 1 to this l e tter responds to the site specific general questions and generic questions enumerated in Enclosure 3 of your letter.
1 Very truly yours, ho Ivan R. Finfr
, Jr Vice Preside
^ > > t1 mi + M ar i b ed to be f re nie th i s
/5 da/ of P
'* b %, 19 80
.Y...'
Notary Pubi ic DAVID C.SMfPLE NOTry rt:jc g- :, 7:v My Camm.n;;a E;.:. g,; ;, g33 1
)
Nl 8009190 Jersey Central Power & Light Company is a Member of the General Pubhc Utikt.es System j
PAGE 1 ATTACHMENT 1 SITE SPECIFIC GENERAL QUESTIONS:
1.
Provide the fol lowing inf ormation per each LP turb ine:
A.
Turb ine type:
RESPONSE
General Electric, type N-1, Serial number 170 x2 90, (1800 RPM, Tancem Compound) 3.
Number of hours of operation for each LP turbine at time of last turbine inspection or it not inspected, postulateo to turbine inspection:
RESPONSE
The LP turbine (A) was taken out of serv ice for a rotor inspection during the spring of 1975.
The total operating hours were 40,977.75.
(B) and (C) rotors were inspected during the 1975-1976 outa's. The total operating hours were 43,857.75.
C.
Number of turbine trips and overspeeds:
RESPONSE
The LP turbines have never experienced an inadvertent overspeed trip during operation.
The turbines are overspeed trip tested af ter each outage and to date, the turb ines have been overspeed trip tested approximately 15 to 20 times.
D.
For each disc:
1.
Type of material including material specifications 2
lcr. ile properties, data 3.
toughness properties data including Fracture Appearance Transition temperature and charpy upper steel energy and temperature 4.
keyway temperatures 5.
critical crack size and basis for the calculation 6.
calculated bore and keyway stress at operating design overspeed 7.
calculated Klc data 8.
minimum yield strength specified for each disc
RESPONSE
Answers to these questions involve data which are proprietary to the General Electric Company, information was prov ided directly to the NRC during a meeting between General Electric and NRC representatives on April 21, 1980. The NRC has informed General Electric that this information is an acceptable reply to this questions.
.e 4;
PAGE 2 II.
Prov ide detaii s of the resul ts of any ccynpleted in serv ice inspections of LP turbine rotors, including areas examined, since issuance of an operating license.
For each indication detected, provide details of the location of the indication, its or ientation, size and postulated cau'se.
RESPONSE
A.
OUTAGE WINTER 1971 The "A"
low pressure turbine rotor was removed f rom the turbine and pl aced on ro l l er assemb l y on the tur b i ne room floor.
Ten buckets from the turbine end, that had the leading edges in the area of the stell ite cu t-Out in 1969, were replaced during the outage. New tie wires and pins were installed in all sections removed.
An ultrasonic check was made of all bucket pins and any cracked pins were replaced.
The entire rotor assembly of (A) turbine was inspectea using the wet eagnetic particle inspection method (magnaglo). The rotor was found to be in good co...
ion.
The last stage buckets of A,
B, and C Rotors were inspected by the dye penetrant method.
The inspection revealed cracks in two buckets as follows:
1.
The no. 12 bucket on the turb ine end of rotor ( A) was found to have e /16" crack extending from the bucket tip radially inward.
G.E.,
indicated that no repairs are required at this time.
2.
Bucket li92 on the "B" rotor generator end was found to be cracked. The crack was blended out as per General E lectric Company instruction.
S.
OUTAGE MAY 1 to JUNE 20, 1972 1.
B and G tow pressure turb i ne rotors were uncovered, but not removed from bearings.
2.
Magnetic particle (magnag!s' inspections were per f ormed on rotor wheels, buckets, and bucket covers; red Cye penetrant inspection was per f ormed on all tie wires. No defects were 'ound on any of the tie wires.
"B" turbine end 13th stage notch bucket was fcund to have a surf ace crack at one of the key holes.
It was poiished out per instructions provided by j
G.E.'s LSTG (Large Steam Turbine Generator' department.
Three bucket covers were found to be cracked from the leading edge to one of the tendon holes on "B" turbine end 13th stage, and three bucket covers on "C" turbine end 13th stage.
All six cracked bucket covers were replaced.
No defects were found on turbine wheels.
3.
-Fourteen 15th stage buckets were replaced that had previously cut out stellite sections. Four 15th stage buckets were replaced that had recentl y
P/ E 3 developed excessive cracks in the ste: lite section.
Stellite sections were cut out on two buckets in "A" turbine because of excessive new y developed cracks.
C.
CUTAGE 1975 MARCH 29-MAY 26 1.
LP turbine "A" was disassembled and a complete inspection was performed on the rotor and buckets.
2.
The rotor was inspected using a magnetic particle (magnaglo) technique and visually and the rotor was found in good cond i t ion w i t h the exception of the 13th stage bucket covers and 15th stage bucket erosion shields.
The
th stage cracked bucket covers were replaced, and the 15th stage cracked bucket erosion shields were polished out to a depth of.045" as per General Electric instructions. All stages of the rotor were inspected per G.E. TIL (756-3) for indication of notch cross key movements. No evidence of movement was found.
D.
OUTAGE WINTER 1975-76
)
i B5 C low pressure turb i nes w ere disassembl ed and inspected.
The rotors were placed on a rotor stard and a visual inspection was per formed on the rotor shaft, wheel s and buckets. A complete rotor assembly inspection was per formed using a magnetic particle (magnaglo) technique. A dye penetrant 1
t i nspec t ion was al so per f ormec on the 13th, 14th and 15th stage buckets. An I
u l tra-son ic test was performeo on turbine B anc C 15th staae bucket pins.
No relevant indications were found on the rotor shaft, turbine wheels or buckets of stage 8 through 14.
15th stage buckets were repaired as per General E l ectric Company recon >1endations.
NOTE During the years 1970 througr.1980 all LP turbine 15th stage bucket, have been inspected and repaired. Wnen cracks or indications were founc, they were polished out or cut ou t as per the G.E. LSTG (Large Steam Turbine Generator) dep a r tm en t.
The actual locations, orientations and sizes of indications found in the bucket stel lite shiel ded areas can be located in the individual outage repor ts.
The 15th stage bucket stellite inserit cracks are suspected to be caused by the stress corrosion related to the original bucket design and manufacturing process.
lil.
P rov i de the nom i n al water chemistry conditions for eacn LP turbine and describe any condenser in leakages or other significant changes in water chemistry to this point in its operating iife.
RESPONSE
PAGE 4 An operating history of t he turb i ne b u i l d i ng sy stem c hem i str y is p.ovided.
Table I contains concensate system nominal chemistry conditions corresponding to the operating periods stated below:
A.
January - June 1970 1.
A salt leek was detected in "C" condenser during the month of January.
Repairs to the condenser curing February shutdown corrected this condition.
At the end of June, there were again indications of a similar situation occurring. Dur i ng Apr i l-May shtudown, an inspection of the condensers revealed extensive growth of barnacles and mussels on the walls.
I t w as obv ious that the present chlcrination system was not udequately controlling the growth of sea life in this area.
Inspection of the Reactor Building and turbine building closed cooling water heat exchangers showed an even more ceticient chlorination control system. The walls of the condensers and the hr.at exchangers were coated w i th a paint which inhibitea marine g row th.
- 2. Numerous problems were encountered with the condensate polishers. The end result of poor and inccmplete regeneration of resen beds was caused by mechanical mal functions and regenerant chemicals which were not within specifications. Replacement of the sodium hydroxide and a complete system maintenance check was necessary to return the polisher system to its proper per f crm ance.
B.
JULY - DECEMBER, 1970 The condenser system had numerous tube leaks during the warm fall and summer months.
As a r.esult many nonroutine chloride analyses were per f ormed on th is system. The reactor f eedwater metall ic impur ities were monitored curing the period.
C.
JANUARY - JUNE 1971 During February 1971 an inspection was made in the "A"
condenser due to increasing conductivity in the condensate system. One leaking tube was found and plugged.
D.
JULY - DECEMBER 1971 Due to the heavy workload during the outage and the large influx of c ' er to radwaste, the dem i neral i zers were not in a recently regenerated condition for startup. The cause of the reactor chemistry problem can be directly attributed to the condition of the condensate domineralizers. As a result the feedwater quality was far below normal. The reactor water cleanup dom i neral i zer res i ns, which were rep l aced shortly af ter startup, received an abnormal cause load as a result of the primary water condition.
As the demineralizers were regenerated, the f eedwater qual ity improved and the primary water was gradual I y returned to ner:ml at the end of the reporting period.
PAGE 5 The differentia! pressure across the domineralizer system has been higher than normal since the November startup.
This increased differential pressure was expected due to higher power level operation and the co.rresponding increase in feedwater flow.
In addition, a higher than norm al crud loading on the demineralizer was temporarily experienced during the initial operational periou following the poison curtain remov al outage.
This crud buildup was gradually corrected by regeneration of the condensate demineralizer beds.
E.
JANUARY - JUNE 1972 Due to problems encountered in maintaining good quality feedwater immediately following the fall 1971 outage, a greater effort was made curing the Spring Outage to regenerate concensate polishers. This was done within the limitations of available space in Radwaste tanks for regenerated water. In spite of the improved condition; however, much the same situation occurred at startup with ionic creakthrough and crud buildup on the demineralizers.
Sample points have been installed at the end of condenser halves to make it possib le to measure the ch lor ine residual in circulating water at each location. This has permitted a more accurate control of chlorine addition for control of algce and marine growth on the condenser tuoos.
F.
JULY - DECEMBER 1972 i
During the first two months of the period, the feedwater quality was I
somewhat less than the desired normal level. The condensate demineralizer resins were not regenerated at the normal frequency during this time.
A total of three condensate domineralizers were regenerated between June and September due to the lack of available space in radwaste for the regenerated sol utions. Although this situation was a contributing f actor to the reactor water problems, there were no other observed detrimental effects.
G.
1973 l
During the year 1973 the condensate and feedwater ionic quality presented fen problems.
H.
JANUARY - JUNE 1974 Emphasis during this period was pl aced on resin analysis to ensure that there w as suf f icient capacity in the condensate polishers at all t im es. A problem in this area during the period was resin loses during regeneration due to tears in the underdrains of the cation tank and resin storage tank.
l.
JULY - DECEMBER 1974 Sample points were installed in the condensate demineralizer regeneration system to allow resin samples to be taken for analysis. Procedures have been set up to check the capacity of resins f ol lowing regeneration and determine the condition of the resin.
This work is part of the augmented
PAGE 6 surveillance of condens ate dem i neral i zer systems cut t ined in Regulatory Guide 1.56. Sampling and analyis of anion resin was started in December.
Insufficient data had been collected by the end of the report period to fully eval uate the resir. First indications were that there was an average 15-20% degradation of the resin to the weak base
'orm. A normal regeneration restorcd the resin to 70-75% of its original strong base capacity.
An investigation was initiated during the period to determ ine methods for reducing condenser tube f ail ures. As part of this program, chemical cleaning of the condenser tubes was discussed.
J.
JANUARY - JUNE 1975 Routine analysis of condensate demineralizers anion resins following regeneration was carried out during the period. As a result of these analyses, the anion f raction of one resin bed was replaced when it was found to lack sufficient capacity a f ter regeneration. The anal yses were also instrumental in identifying mal functions in the regeneration sequence.
K.
JULY - DECENBER 1975 The condensate domineralizers were subjected to an almost constant influx of salt in the condensate due to condenser tube f ailures. Due to the level of exhaustion of beds removed from service, abnormal difficultly was experienced in regenerating the resin. This created a lack of space in radwaste which further restricted the frequency of regeneration. The net result on numerous occasions was a restriction of the plant electrical output. In an effort to cartially solve this problem, the anion fraction of two of the mixed bed demineralizers was replaced when regeneration problems were encountered with the exhausted resins, in spite of the continuous problems with the condensers, there was no major breakthrough of chlorides in the condensate demineralizer system. The sampiing and analysis of condensate and feedwater was significantly increased dur ing the per iod. This close surveillance, coupled with the quick response by operations personnel was instrumental in preventing any abnormal concentrations in the reactor primary system (See Tab le 1 ).
L.
1975 - 1976 0UTAGE (CCNDENSER RETUSING)
The Oyster Creek main condensers were retubed using titanium tubing. Tube replacement was necessitated by excessive condenser tube leakage due to the effects of erosion - corrosion. The salt water inleakage into the condensate system caused operational dif ficulties which resulted in plant operation at reduced power.
Since retubing, the titanium tubes have functioned satisfactorily in service with the exception of a limited number of vibration induced tube failures.
o
PAGE 7 v.
1976 - 1977 The turb ine buil ding systems operated normally.
N.
JAN'JARY 1978 - JUTE 1979 On April 2, 1978 a leak occurred in'"A" north condenser. The load was reduced to 465 Mwe and "A" condenser was entered.
Two leaking tube were plugged anc then the end of one of the previously plugged tubes was replugged in the north condenser. "A" south condenser was checked for leaks and none were found. Reactor water conductivity increased to 2 umho dur ing the leak.
O.
JUNE 1979 - 1980 OUTAGE Price to this outage there were no condenser problems.
IV.
If your plant has not been inspected, describe your proposed schedule and approach to ensure that turbine cracking does not exist in your turbir.e.
RESPONSE
Our turoine has been inspected, see i ten 5 below.
V.
If your pla t has been inspected and plans to return or has returned to power w i th crac ks or other def ects, provide your proposed schedule for the next turbine inspec' ion and the basis for this inspection schedule, incirJing postulated defec-growth rate.
RESPONSE
The turbine rotor assemblies do not have at the present time any relevant indications which would require action during the next outage.
AlI d isclosed def ects were d ispos itioned as per General Electric Company recommendations.
i VI.
Indicate whether an analysis and evaluation regarding turbine missiles have been performed for your plant and prov ided to the sta f f.
If such an analysis and evaluation has been performed and reported, p l ease prov ide appropriate ref erences to the avai lab l e docume.tation. In the event that such studies have not been made, consideration should be given to scheduling such an action.
RESPONSE
Amendment NO. 11 to the Oyster Creek Facility Description and Safety Analysis Report, section IV-5-1, addresses the analysis and evaluation 4
PAGE 8 regarding turbine missiles.
1 GENERIC QUESTIONS 1.
Describe what quality control and inspection procedures are used f or the disc bore and keyway areas.
RESPONSE
After the rough machined wheel / disk forging has been tempered, material is removed f r om surface locations to measure mechanical properties. Th e forging is then subjected to a 100% volumetric ultrasonic inspection. if the test results meet stringent acceptance standerds, the forging is released for final m ac h i n i ng. During final machining, attention is cont i nua l l y pa id to the finish, contour, and dimensions of every surface.
For instance, the keyway depth, width, location, radii, and surface finish for every wheel is checked for conformance to drawi ngs.
Quality control personnel assure that tolerances are maintained.
Any devlation from accepted tolerances are reported to engineering for disposition.
Only coolants and l ubricants approved by eng ineer i ng are us ing in the manuf acturing and assembly process.
These coolants and lubricants have undergone extensive laboratory corrosion testing to ensure their acceptability prior to their approval for use in manufacturing. Periodic sampling is done on all such fluids to verify that their chemistry is witnin acceptab le limits. It required, corrective actions are taken to maintain the chemistry within limits.
After finishing machining, each wheel is thoroughly cleaned and given a magnetic particle inspection of all surfaces.
If acceptable, the buckets are assembled and the wheel is static balanced. After assembly on the shaft, each wheel is inspected and measurements are made to assure its proper location. The assembled rotor i, then spun to 20% overspeed following a high speed balance. Finaiey, after a magnetic particle inspection of the buckets, the rotor is cleaned to prepare for shipment.
II.
Provide detail s of the General Electric repair / replacement procedures for faulty discs.
RESo0NSE:
Stress corrosion cracks have not been observed to date in nuclea wheels manuf actured by General Electric, and we do not anticipate that removal or rep l acement of wheels will be required because of this phenomenon. The water e asion which has been observed in the keyways of wheel s on several non-reheat machines is being studied intensively. We currently bel leve that the erosion process is sel f-limiting and shoul d not require the replacement of any wheels.
PAGE 9 111.
What i rrr ed i ate and long term actions are being taken by General Electric to minimize future " water cutting" problems with turbine discs?
What actions are being recorrnended to util ities to minimize " water cutting" of discs?
t
RESPONSE
No immed iate actions are required to minimize water erosion because of the apparent self-limiting nature of the phenomenen. However, it future inspections show an unexpected progression of the water erosion, appropriate operating restrictions and/or modifications will be recorm end ed.
IV.
Describe fabrication and heat treatment sequence for disc, including thermal exposure during shrinking operations.
1
RESPONSE
The wheel / cisk f org ings are heat treated in the rough machined condition.
The heat treatment consists of soaki ng at a temperature above the upper critical temperature with the time and temperature suf ficient to ensure complete auster.itization throughout the forg ing, following by a quench in cold, v i gorously circul ated water for a suf ficient time to ensure complete transformation throughout the section. The forgings are heated unifornly to a tempering temperature below the lower critical temperature and held for 3 suf f icient time to sof ten to the desired tensile range.
At +cr temporing, the f org ings are still-air cooled to roon temperature.
After final machining, the wheel s ( disks) are uniformly heated in an electric furnace to a temperature below the embrittling range, but suf f iciently high to increase the wheel diameter enough to assemb le on the shaft with the required shrink fit.
NOMINAL WATER CllEMIsTRY FOR L. P. TURBINES (CONDENSATE)
TABLE I READING FOR INDICATED TIME PERIOD
"^
Conduct-Dis-Sus-MET / LS ivity solved pended P"
umilo/CM 02 Solids Chlorides FE Cu NI CR JAN/ JUNE Not 6.95 2.75 5.23 5.5 1970 6.69
.221 12.1 19.8 Recorded JULY /DEC Not 1970 6.51
.173 8.1 10 Recorded 7.66 1.3 1.23
.162 JAN/ JUNE
- 44
- 37
- 026
- 031 Chlorides reading 1971 6.48
.0986 6.5 10 30 d.55 6 1.60 d.052 d.017 fgg pynth of June JULY /DEC
- 13.9
- 84
- 155
- 038 Plant shut down 1971 5.31
.106 10.3 10.4 4.421 61.78 f.197 d.0072 during month of Oci JAN/ JUNE 6.6
.082 12 13 21
- 11.9
- 174
- 012
- 024 1972 4 1.62 d.664 d.04 4.012 JULY /DEC 6.46
.238 12.8 15.7 46.4
- 7,78
- 2.23
- 066
- 042 1972 61.63 61.17 d.089 d.07 IAN/JUNF
- 13.67
- 69
- 026
- 257 Plant shut down for 6.1
.098 15.5 13 25.4 1973 63.54 f.878 d.042 6.0558 month of May JULY /DEC
- 16.12
- 003
- 001
- 147 1977 6.21
.116 13.88 18.68 25.25 d5.03 f.26 d.024 f.041 JAN/ JUNE 6.13
.068 27.95 16.50 42.12 61.311 d.054 d.0616 f.027 in May and June 1874 JULY /DEC
- 4.52
- 029
- 011
- 024 1974 6.18
.139 18.8 25.2 46.2 f.158 f.092 f.183 4.019 AM/ JUNE
- 11.07,
f.064 d.279 f.12 in April
- 201
- 172
- 181 Plant shut down 6.26
- 110 19.25 28.25 29.6 1975 d.104 JULY /DEC
- 15.0
- 303
- 906
- 072 1975 6.51
.183 21.36 40.33 49.6 d.823 f.083 lo.245 d.113
- Millipore demte Ron
NOMINAL. WATER CllE!!ISTRY FOR I. 1'. 'l u Rii l N ES (CONDI.t4SATt;)
READING FOR INDICATED TIME PERIOD COMMENTS Conduct-Dis-Sus-pil fuity 3 solved pended umAo/CM 02 solids Chlorides FE Cu NI CR
- 5.4
- 075
- 200
- 049 Plant shut down
^'
I 6.44
.074 35 23.9 26.5 f.7 f.154 6.164 4.0092 January & February c5.55
- 48f
- 199
- 118 Plant shutdown in
.r AN/Dl:C 1977 6.44
.091 25.5 41.22 20 dl.49 4.117 233 3.184 May, June, 6 July
- 27.8
- 066 41 A.187 Plant shut down in
.lAN 1978 to Ath; 1979 6.37
.14 69 88 54.9 45.85 d.08
.19 4.445 Oct/Nov. of 1978.
Data not available
__ l for Apri!/May 1979
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