ML19351E177
| ML19351E177 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 05/24/1967 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML19351E176 | List: |
| References | |
| NUDOCS 8011250719 | |
| Download: ML19351E177 (9) | |
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t YANKEE NUCLEAR P0dH1 STATION OPHIATION REPORT NO. 76 For the month of APRIL 1967 O
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This report covers the operation of the Yankee Atomic Electric Company plant at Rowe, Massachusetts, for the month of April 1967 At the beginning of the period the plant was operating at approximately 183 MWe.
The plant load gradually decreased to 181 MWe by the end of the period as circulating water inlet temperature increased from approximately 39 to h3 F.
There was also Indication of deteriorating condenser performance.
On four different occasions plant load was reduced to preclude an inadvertent shutdown due to severe weather conditions.
The duration of each load reduction was approx-imately one hour.
One shipment of spent fuel was made on April 21.
This shipment is the twent3 -first in the series of spent fuel shipments, bringing the number of elements shipped in the ten element cask to 200 and the total O
number of elements shipped to date to 216.
Between April 26 and 28 twelve control rod absorber sections and twelve follower sections, removed rrom the reactor during the Core V-VI shutdown, were loaded into the control rod shipping cask for subsequent shipment and disposal. Previously, on April 4, the two, spare hafnium control rod absorber sections were shipped from the site for modification to unitised rods.
Control rod groups B, C, and D vure banked at 88 - 1/8" on April 6.
This is the fourth step of the Core VI maximum withdrawal limitation program fec distribution of guide block wear.
Control rod exercises were conducted on April 18.
All rods functioned normally.
1 The vapor container air leakage rate was normal throughout the reporting period.
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Uo plant shutdowns or reactor scrams occurred during the month of April.
J Plant Maintenance The following is a list of major plant maintenance items performed by the plant staff during the month of April,1967:
1.
Two control rod drive shaft dash pots, renoved from the reactor during the Core V-VI shutdtwn, were internal-ly decontaminated and inspected.
2.
Three plungers, the carbon seal rings and three suction valve springs were replaced on No. 1 charging pump.
3.
A weld repair was effected on a welded joint leak on the outlet line of the boric acid mix tank.
4
. 4.
Mechanical seals and the shaft sleeve were replaced on l
the low pressure surge tank cooling pump.
5 The spent fuel pit grappling tool was overhauled and repaired.
6.
Fittings to permit chemical cleaning were installed on the steam generator blowdown radiation monitoring drums.
7 A new filter for the circulating water punp bearing veter system was installed.
Instrumentation and Control The following is a list of the mejor instrumentation and control maintenance items cerf ormed by the plant staff during the month of April 1967:
1.
Orifice flanges for the water clarifier flow trans-mitter iare replaced and the instrument recalibrated.
l 2.
A local, high level alarm for the primary auxiliary building floor drain sump was installed.
3.
Operational inspection and checks were performed on the l
two off-site ai r particulate radiation monitors.
'tbd 4.
A water temperature rec ording thermometer was installed in the tailrace of Sherman Station.
Reactor Plant Ferfonnance Core reactivity depletion was normal at approximately
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0.74 a K/K per 1000 MWtD/MTU.
A further inspection of the two Core V zircaloy fuel assemblies was conducted during the period. This inspection was primarily directed toward obtaining post irradiation tube diameters of the removable fuel tubes. Data reduction has not been completed.
However, no ancmalies were noted.
The following parameters were determined by means of incore instrumentation at 600 MWt, 52h.8 F Tavg, 905 ppm boron, control rod groups B, C, and D at 87 6/8 and group A at 82 6/8:
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- 1. 9'l Fall
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3.2 Minimum DNER
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0 591.0 F Maximum Outlet Temperature
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'- Secondary Plant Performance Feedvater heater terminal difference at 181.5 MWe, 1.60" Hg backpressure and 523.7 F Tavg:
- 1 -9.5 F
- 2 -18.6 F
- 3 -18.80F Condenser terminal difference:
37 F
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In Operation Peport No. 75 for March, 1967 the readwater heater terminal diiferences were incorrectly reported to be, #1 -5.6 F,
- 2 -17.7 F, and #3 -8.5 F.
These should be changed to read #1 -8.50F,
- 2 -17.7CF, and #3 -15.9 F.
Chemistry On April 3 an increasing +, rend in steam generator water chloride concentrations was detected. The following day the average concentration had increased to 0.80 ppm with a maximum of 1.05 ppm in f-No. 1 steam generator. Inasmuch as there was a variation between concentrations in the individual steam generators, and analysis of the secondary feedvater did not positively establish the presence of a condenser tube leak, the chemical treatment phosphate became uspect.
Analysis of the phosphate revealed a chloride contamination in a ratio of 1.65 ppm chloride to 100 ppm phosphate.
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Cteam generator :hloride concentrations were returned to normal by increased blevdown rates, and new chemical treatment phocphate was purchased from a different vendor. Each phosphate shipment received is now being analyzed for chloride contamination prior to use.
As a result of the variation in steam generator blowdown. ves meaningful primary to secondary side leak rates have not been obtainable; however, it is estimated to be less than 25 gpd.
The main coolant boron concentration decreased-from 907 ppm to 809 ppm during the period. Average main coolant iodine-131 specific activity was 2.05 x 10-5 ue/ml; I-131/I-133 atomic ratio was 0.79 The average system crud level was 0.20 ppm.
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r A main ecolant cruri sample collected on April 10 had the following radiochemical un t]v.:ca dp:/ng crud Cr-51 Ef-181 Mn-Sh Fe-59 Co-58 Co-60 6
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6 1.23 x 10 6.02 x 10 1.07 x 10 1.19 x 10 h.35 x 10 1.2h x 100 A main coolant gas sample collected on April 20 had the following radiochemical analyses: uc/cc gas Xe-133 Xe-135 Ar bl
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h.2h x 10-3 5.67 x 10-3 3 92 x 10-1 Health and Safety Three shipments of radioactive vaste were made during the period ccmprising 155 drums with a total activity of Th9 me.
One shipment of spent fuel was made consisting of eight assemblies with a total activity of 12.35 megacuries. Gamma radiation levels on contact with the cask were less than 2 mr/hr with a maximum level of 2 mr/hr detected at the valve bcx.
Ileutron radiation levels at one meter were approximately 0.8 mrad /hr fast and 0.02 mrad /hr slow.
2 Beta-gamma contaminaticn levels sere a maximum of 2 x 10-9 curies /100 cm,
There was no detectable alpha contamination.
During April the vaste disposal liquid releases totaled 285,000
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gallons containing 786 uc of gross beta-gamma activity and 77.785 curies of tritium. Gasecus vaste releases during the same period totaled 131.h me of gross beta-gamma activity.
Secondary plant water discharged during the period consisted of 172,000 gallcns containing a total of 10 91 ue of gross beta-gamma activity and 2.323 curies of tritium.
In addition to the foregoing, an inadvertent gas release occurred on April h.
This 214 cubic foot release, comprised of 9-Lue-of beta-gamma activity and 60.5 cc of tritium as a gas, resulted fremYn unlhtentional k
venting of the low pressure surge tank via the sample hood while drawing a pressurizer gas sample. Prior to this release the capillary vent line was being normally recirculated to the low pressure surge tank. At 3245 hours0.0376 days <br />0.901 hours <br />0.00537 weeks <br />0.00123 months <br /> the capillary vent was valved to the sample hood to establish equilibrium flow conditions prior to sampling.
Inadvertently, the recircula-tion valve to the 1cw pressure surge tank was left open permitting a back flow from the surge tank to the sample hood. At 1515 hours0.0175 days <br />0.421 hours <br />0.0025 weeks <br />5.764575e-4 months <br /> the error was detected and the valve closed. Concentrations of the gases released from the prbmary vent stack as a result of this release were below MPC.
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. Radiation exposure doses for Yankee plant personnel, as measured by film badge, for the month of April,1967 were:
l Average accumulated exposure dose 106 mrem Maximum accumulated exposure dose 354 mrem Operations The following Operating Instructions were revised and reissued during the period:
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OI SQL E2 Changing Plant Load OI 50h D6 Routine Power Operation Attached is a summary of plant operating statisti o and a plot of daily average load for the month of April,1967
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YANYRR ATOMIC ELEETRIC COMPANY -- OPERATING
SUMMARY
April 1967 10 NTH YELR TO DATE ELETRICAL Gross Generation WH 130,728,100 402,997,500 6,765,458,000 Sta. Ser vice (While Gen. Incl. Losses)
WH 7,772,030 23,952,152 453,974,974 WH 122,956,070 3(9,0h5,348 6,311,h83,026 het Output Station Service 5.95 5 9h 6.71 Sta. Service (While Not Gen. Incl. Iosses)
WH 0
387,215 24,182,682 Ave. Gen. For & nth (719 hours0.00832 days <br />0.2 hours <br />0.00119 weeks <br />2.735795e-4 months <br />)
W 181,819 Ave. Gen. Running (719 hours0.00832 days <br />0.2 hours <br />0.00119 weeks <br />2.735795e-4 months <br />)
W 181,819 PIANT PERFORMANCE 28.60 28.95 28.h9 Net Plant Efficiency g
Net Plant Heat Rate Bru/WH 11.033 1,788 11,979 Plant Operating Factor 99.6h T5.80
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Reactor Plant Availability 100.00 90.20 m
NUCLEAR
}0!rrH 00RE VI TOTAL Hours Critical HRS 710.00 3,938.24 4T,663 92 0
2 Sh.
Times Scrammed Burnup WD/MPU 862.11 h,106.5h Core Average Region Average WD/MTU 857.284 u,122.166 20,89h.67 A (INNDt)
B (MIDDLE) 1,029.934 h,912.524 12,587.81 C (OUTHt) 69h.997 3,298,Shh 3,298.5h
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