ML19351E221
| ML19351E221 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 04/28/1966 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| References | |
| NUDOCS 8011260226 | |
| Download: ML19351E221 (11) | |
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YANKEE NUCLEAR POWER STATION OPERATION REPORT NO. 63 For the month of L
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This report covers the operation of the Yankee Atomic Electric 4
Company plant at Rowe, Massachusetts, for the month of March,1966.
Except for two short periods of testing, the plant remained base loaded at 16$ M4e throughout the period. The plant net output since startup reached 5 billion killowatt hours on Fbrch 27.
The power tests of last month (Operation Report No. 62) were re-peated this month with the power dip at neutral pH preceding the power dip at elevated pH.
Refer to the Cnendstry and Reactor Performance sections of this report for details of this test program.
Repairs were completed to the 10-element spent fuel shipping cask (Refer to Operation Report No. 62 for details). New lifting yokes car.
with a slightly wider opening were installed on the car and one inch square spacer bars were welded to one end cf the false cask head.
These modifica-tions will allow the crash frame to restrain lateral motion of the cask, as was intended in the design of the shipping container. The fractured yokes were shipped to Westinghouse for analysis of the failures.
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The loaded cask was placed on the rail car,and the fourth spent fuel shipment was made to the reprocessing facility on March 8.
The empty cask was returned to the site on March 28 and prepared for the fifth shipment on March 30. A railroad strike prevented shipment and at the end of the period the cask remained on our siding.
Continued monitoring of the pressurizer safety valve leakage has indicated an increase in the leakage rate.
At the end of January the leakage rate was measured at 30 lbs./hr., by the end of February the leak-age rate was 60 lbs./hr., and at the end of this reporting period the leakage rate had increased to 160 lbs./hr. Replaceable parts have been received and a plant shutdown has been scheduled for early in April to make repairs to this valve.
(~T An air charge was made to the vapor container on March 17th to i -
compensate for leakage.
The elapsed time since the previous charge was 96 days. During tnat period it was calculated that 320 lbs of the 65,500lbs.
of air in the vapor container had leaked out. The leakage rate over this period was calculated to be.00$ %/ day.
Data +.aken before and after the charge indicated that 380 lbs of air was charged to the vapor container. The gas flowmeter indicated that 360 lbs. was actually charged.
Da Fbrch 22 an additional h00 lbs. of air was charged to the vapor container. Sufficient data nas not been obtained since the air charge to be able to calculate any change in the leak rate.
Spurious power level signal " spikes" have been appearing with increasing frequency on two of the three power range channels (channels 6 and 8). This is reason for concern because two of these pips occurring
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simultaneously will cause a reactor scram. There is a possibility that A
this is being caused by the gradual deterioration of thimble cabling under
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neutron flux. This problem was noted at the end of Core III and cable re-placement at that time corrected the problem.
Periodic cable replacement
G which was also instituted at that time was thought to be a permanant solution. Careful calibration of the alarm set points of the power range channels has reduced the frequency of these alarms. Records will be kept on the frequency of these alarms until the plant shutdown next month. If a problem seems to exist at that time, detector in-thimble cabling will be replaced.
Follcwing the reactor " power dip" test on March 25th, the monthly contr rod test was completed. All control rods that were not used during
- power swing were individually driven in to 81 inches and then witharawn to their starting position to ensure that all control rods remin operational.
All rods functioned routinely and no abnormal conditi ns were observed.
The recently installed raw water heater in the water treatment plant has been placed in service. Its purpose is to warm the cold pond water before treatment, which increases the overall efficiency of the
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water treatment plant. The heater is operating satisfactorily and has 1-allowed the water plant to operate near capacity.
Fbintenance The following is a list of the major items carried out by the plant staff during the nonth of March,1966.
1.
Removed the dash pot from a control rod drive shaf t and prepared it and another one for shipment for disposal.
2.
Relecated the potentially contaminated storage building floor drain from the waste disposal building floor drains system to the ash dewatering sump tank.
3.
Rebored the bushings on the reactor plate and barrel s
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handling fixture.
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A 6" diameter handhole was cut in the top of the primary auxiliary building sump tank to facilitate internal cleaning of the tank.
5 Installed a heat exchanger to warm the incoming pond water to the water treatment plant, which will allow normal output during the colder months.
6.
Installed new carbon ring packing in the No. 1 charging pump.
7.
Reinstalled the No. 1 gravity drain tank pump.
8.
The rotoclone drain (on the incinerator) was modified to facilitate cleaning when plugged.
9.
The hydraulic cylinder in the fuel handling system No.1
'~1 laydcwn mechanism was overhauled.
10.
A new gasket was installed on the outer door of the vapor container personnel hatch.
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. Instrumentation and Control The following is a list of the major items performed by the plant staff during the month of March, 1966.
1.
Made several repairs to the vapor container air particulate radiation monitoring system.
2.
Performed maintenance on the primary vent stack gas monitor.
3 Assembled and installed a thermocouple on the outside bottom of the vapor container to measure skin temperature.-
14. Repaired the nuclear instrumentation recorder.
Repaired the air ejector radiation monitoring system.
n 6.
Repaired the charging flow indicator on the main control board.
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7.
Tested for proper functioning, the isolation trip valves on the vapor centainer air particualte monitor system.
8.
Checked the calibration of the six power range level alarm and scram set points.
9.
Recalibrated the four main coolant
.mp bearing temperature indicators.
10.
Repatred the wind speed transmitter and recorder chart drive.
Reactor Plant Performance In a further attempt to explain core reactivity changes associated f]
with main coolant pH, a second series of tests was performed. This series k/
attempted to duplicate as much as possible the tests performed during February 1966. The power reductions in the February tests were to about 130 WT, which required extrapolation of results to the zero power point.
To improve upon the data, the second series of tests reduced the reactor power to minimum generator load, which is about 30 NT.
Preliminary data was taken to insure that normal burnup conditions existed. On March 15, a power swing from 185 We to 10 We to 18$ Ne was performed with the main coolant system pH unadjusted. During the transient pertinent data was gathered by the reactivity computer.
Fo2 lowing the transient, reactivity data indicated a period of lower than normal burnup. This " flat spot" began March 16 af ter a boron dilution operation for reactivity insertion and continued until ammonia was added on March 22.
It is possible that this " flat spot" was caused by boron being slightly consentrated in the pressurizer because of the
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safety valve leak. A normal reactivity gain rate was experienced following
/es the ammonia addition with a slightly less than normal total reactivity gain. The expected total gain from elevated pH approximates 0.7% 6 K, whereas this gain approached 0.6% 6 K.
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-h-On March 25, the power swing from 18$ FWe to 10 IWe to 185 FWe was repeated at elevated pH.
Although final results will not be avai.lable for some time, somet easily observable results are:
1.
That a shift in control rod worth acting to slightly reduce the relative worth of the central group.
2.
That a large portion of the reactivity change associated with a change in pH is attributable to a change in the amount of reactivity tied up in Doppler coefficient.
A flux wire irr ation under the following conditions was analyzed with the following result 18$ FWe,1.39" Hg back pressure, $97.1 FWT Control rod groups B, C and D at 87 6/8", group A at 701/8".
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- J Fuel assembly H3 of the instrumented quadrant, showed the worst conditions:
Fq
= 2.h5 Fd H
- 1*99 q"DNBR = 3.21 max. hot channel outlet temperature = $91 F Secondary Plant Performance Feedwater heater terminal difference measurements made during the period were:
m El = 8.80F
- .2 = ll.80F
- 3 = 10.60F The generator load during these measurements was about 185 FWe.
The continuing poor performance of number 2 heater has resulted in the scheduling of an inspection during the outage next month.
Measurements of condenser performance have indicated a gradual increase in terminal difference. A cleaning of the condenser tubes will be performed during the outage.
Chemistry The main coolant oxygen level remained below the limits of detection throughout the period. The detection limits are: $0 ppb for
.)m un-adjusted pH operation and $ ppb for high pH operation.
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The prinary to secondary leakage in the #3 steam generator 4
calculated as h to 6 gallons per day. This leak was first detected during July 1965 (Operation Report No. $5) and calculated as 2 gallons per day.
No primary to secondary leakage has been detected in any of the other three steam generator.
Two independent samples wure taken from the pressurizer gas phase.
The analyses are as follows:
- 1 sample
- 2 sample Flow Rate 55.1 lbs/hr 52 lbs/hr Gas Concentration 50.2 cc gas /KG steam 82 ce gas / KG steam Gas Analysis:
02 0.lh%
0.08%
N2 1N*1 5 lb'9 %
H 79*1 N Ob' I 2
The following analysis is from a pressurizer drain sample:
0 < 50 ppb specific activity h.5 x 10-3 pc/ml
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2 pH 5.6 boron 630 ppm conductivity ~ h.5 phos At the start of the period the crud level was about 0.07 ppm with unadjusted pH.
The crud remained at this level until March 15, when a " load dip" was performed. The crud level did not increase until after the transient. At this point, water was flashing to steam in the bleed line. This continued for 7 minutes and coincided with the increase in main coolant T from 516oF to 527 F.
The gamma detector near the bleed line registered h0 mr/hr and the crud level increased to 1.3 ppm following av the flashing incident. It is believed the crud came from the bleed line rather than from the core.
The crud level decreased and was measured at 0.06 ppm on March 22 when the main coolant pH was raised by the addition of ammonia as NH 0H.
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The crud level was about 0.59 ppm until rod motion associated with the power dip on March 25 increased the level to 3 ppm. The level gradually decreased and was measured at 0.h0 ppm at the end of the period.
The results of the analysis of a main coolant gas sample taken near the end of the period are:
A - hl 1 3 x 10~1 pc/cc of gas Xe - 135 1.5 x 10-2 pc/cc of gas Xe - 133 2.8 x 10-3 pc/cc of gas The iodine -131 specific activity was measured at 19 x 10-5 pe/ml and the I-133/I-133 atomic ratio sas 0.65.
These figures are essentially the same as those previously reported during Core V operation, and indicate that no significant fuel cladding defects exist in this core at this time.
Increases in the boron concentration of samples of water taken from the pressurizer drain line were noted. This increase in the boron s
concentration in the pressurizer corresponds to increased leakage of the m
pressurizer safety valve. As the water in the pressurizer flashes to i
steam and leaves via the leakage path, the boron remains and concentrates in the pressurizer.
3 s This concentration of boron in the pressurizer tends to reduce the 4
boron in the main coolant system. The rate of boron reduction about $ ppm per day, in the main coolant system with large leakage of the safety valve, balances the burnup of the core and gives the appearance of a reactivity
" flat spot".
Health and Safety Daring the month of March 1966, one shipment, consisting of three drums of radioactive waste, was made for off-site disposal.
Each drum was pbced in a five ton concrete cask for shipment. One drum was a filter
- u. tit used in the cleanup of the gravity drain tank. The other two drums each contained one control rod drive shaf t dashpot. One removed after Core III, the other after Core IV.
The total activity of the srtipment was calculated to 2.3h curies.
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Liquid waste disposal releases totaling 7h,000 gallons containing a gross beta-gamma activity of 108 me and 127 curies of tritium, were dis-charged during the month of March. Gaseous waste released contained a total gross beta-gamma activity of $1 me.
In addition to the above releases, 258,700 gallons of water con-taining 1.19 curies of tritium were discharged from the secondary plant.
The grcss beta-gamma activity of this water was les ; than 10 jac.
One shipment of ten spent fuel assemblles was made to the re-processing f acility during the month of March. The total activity of the shipment was calculated to be h.$ megacurie contamination levels were less than 1 x 10 g. Non-fixed beta-gamma surface 2
curies /100 cm. No alpha contamination was detectable. Cask radiation levels were generally less than 1 mr/hr contact with 8mr/hr being measured on the valve box.
Levels at one meter were less than 0.1 mr/hr above background.
Radicactive levels 7m of the transport vehicle on contact and at two meters were less than 0.1 mr/hr above background.
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The prima y auxiliary batiding sump tank was internally cleaned using a procedure similar to that used laat month to clean the gravity drain tank.
(see Operation Report #62) The principle difference being the washed off material was transferred directly to drums as vaste to elim-inating the filter unit. A total of 16 drums of material resulted from
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this operation. Af ter the drums were prepared by adding cement and rolling, lh drums showed contact radiation levels of 30-200 mr/hr, while two drums were approximately 1 r/hr on contact. The drums were placed in storage for later shipment.
Personnel exposure for Yankee plant perscnnel as measured by film hadge for the month of March 1966 were:
Average for all station p.rsonnel 87 mrem Maximum individual exposure 3h7 mrem
Design Changes The following are desariptions of changes made during the reporting period.
1.
Trip circuit for switchgear room ventilation fans. A trip circuit has been installed which will automatically trip these fans on low main coolant pressure. This will eliminate the necessity of a c ntrol room operator leaving the control room during accident conditions to shut down these fans. To avoid the use of primary plant instrumentation circuitry, the ini-tiating signal used is the pneumatic signal line of the pre-cision pressure gauge used by the Reactor Engineering Dept.
A manual trip switch has also been installed on the main control board.
2.
Bleed -line trip valve closing switch. A switch has been in--
stalled on the front of the main control board to close the bleed line trip valve. In th9 event of a total loss of AC power, this valve should be closed to conserve main coolant liquid, this switch now provides an easy way to perform this action.
3 Turbine speed monitor switch. The turbine speed-valve position recorder would automatically switch from " turbine speed" to
" valve positivn" just below synchronous speed (1800 rpm) as the unit was started up.
This installed switch bypasses the auto-matic feature fo the recorder and allows the operator to con-tinue to monitor turbine speed during the critical portion of a turbine-generator startup.
Once the generator is phased, this bypass switch is opened an1 the recorder automatically switches to " valve position".
r Operations The following Dnergency Instructions were revised and reissued during March.
H $05-B8 Partial loss of Main Coolant Flcw below h85 WT.
E $05-B13 Excessive Radioactivity Level.
H $05-B15 Malfunction of Primary Pressure or Level Channels.
E 505--c2 Major Rupture of tne Main steam Line.
Attached is a sumrary of plant operating statistics and a plot of Daily Average Load for the month of March 1966.
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YANKEE'. 0MIC ELETR OMPANY -- OPHIAL >G
SUMMARY
MARCH 1966 ELECTRICAL MONTH YEAR TO DATE Gross Generation KWH 137,771,100 399,130,600 5,389,971,500 Sta. Service (while Gea. Incl. Iosses)
KWH 8,18h,729 23,6hh,870 370,057,36h Net Generation KWH 129,586,371 375,h85,730 5,019,91h,136 Station Service 5.9h 5.92 6.87 20,091 22,261,669 Sta. Service (While Not Gen. Incl. Iosses)
KWH Ave. Gen. For Month (7hh Hrs)
KW 185,176 Ave. Gen. Running (7hh Hrs)
KW 185,176 PIANT PmFORMANCE Net Plant Efficiency 29.23 29.23 28.50 Net Plant Heat Rate Btu /KWH 11,676 n,676 n,975 Ibs. Steam / Net KWH 13 9h 13.9h Circulating Water Inlet Temp.
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OF 35 h0 Mi ni =!=
oF 32 32 c,
Plant Operating Factor 99 30 99.12 69.73 I
Reactor Plant Availability 100.00 99.90 81,ho NUCEAR
}ONTH CORE V TO DATE Times Critical 0
15 372 Hours Critical HRS 7hh 3381.50 39,3h2.h6 Times Scrammed 0
1 50 Equivalent Reactor Hours @ 600 W t HRS 738.79 3223.h8 29,382.52 Average Burnup of Core WD/MPu
- Control Rod Position at Month Ed Equilibrium at 597 NT
- RmION Group A Rods out-inches 87 0/8
}ONTH TOTAL BURNUP 07 6/0 A (INN m) 893.95 19,222.83 Group B 87 6/8 B (MIDDLE) 1003.hl 11,1h7.63 Group C 87 6/8 C (0UTm) 771.90 3,3h8.8h Group D ZIRCAIOY TEST ASSEMBLIES 12h2.51 5,561.23 bl5 ppm Boron Ammonia < 1 ppm
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