ML19351D999
| ML19351D999 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 12/20/1962 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| References | |
| NUDOCS 8011250381 | |
| Download: ML19351D999 (10) | |
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i YANKEE NUCLEAR POWER' STATION OPERATION RFPORT.NO. 23 For the-month of G
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' December 20,.1962-
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This report covers the operation of the Yankee Atomic Electric Company plant at Rowe, Massachusetts for the month of November,1962.
The plant ~was operated at a power level of approximr.tely 166 MWe until November h, when it was taken out of service in order to perform a number of minor maintenance j;bs and inspections. During the shutdown, two test sections of stainless steel plate were removed from the walls of the shield tank cavity. One specinen was taken at an elevation of approximately 5 feet above the cavity floor while the second piece was removed from a location approximately 11 feet above the floor. These test specimens were removed from the walls of the cavity in order to provide representative samples for use in evaluating the c:rdty contamination problem. The primary effort during the period was directed toward detemining the nature of the contamination as well as the percentage of the total radiation dose in the shield tank cavity due to the contribution of activity from each side of the steel wall plate.
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t Upon return of the plant to service and the licensed pcwer level of $h0 MWt, gross electric output was improved to approximately 168 MWe.
The improvement in electrical output was made possible by the recovery of the condenser circulating water vacuum after plant startup. On November 9, the circulating water system vacuum was again lost due to a change in the position of the partially closed condenser circulating water discharge valves. Moving the valves toward the fully open position resulted in the
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discharge line vacuum dropping from 15 inches to about 7 inches of Hg.
x-During a routine inspection within the vapor container, it was noted that the temperature of the pipe connecting the pressurizer to the pressurizer safety and relief valves was considerably below the normal operating ra:ge of $$0 - 600 F.
Plant load was therefore reduced to 100 MWe on November 21 in order to investigate the cooling of this connecting pipeline. After collection of pipeline temperature data and review of all p
possible causes of the cooling, it was decided to obtain a sample from the pipeline by operation of the manual vent valve. Analysis of the sample v
showed concentrations of boren in am m.ts which were considered possible as a result of residue left from previous cold plant shutdowns and startups.
Analysis for hydrogen on the otherhand showed positive results. Since all indicatiorspointed toward a gas blanketing problem and the cool ccnnecting pipe condition existing only between the solenoid relief valve and its motor-operated isolation valve, it was decided to operate the solenoid relief valve. After opening sharply, blowing for four seconds, and closing sharply, the line to the relief valve returned to normal temperature. It was therefera concluded hydrogen gas had caused thermal blockage in the vertical safety and relief valve line, the hydrogen probably being stripped by condensing steam action.
While the plant was cc ating at the reduced load, the condenser circulating water system siphon was reemered and maintained for the remainder of the month. The return to licensed I n l power level was begun on November-
- 23. By November 26, an equivalent electrical load of approximately 169.5 MWe
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_2-had been achieved.. ' Plant operation continued at this' power level until the :
end of the month.'
Nuclear instrumentation power range-channels Nos. 6, 7 and 8 contin-
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ued to experience spurious signals of magnitudes large enough to initiate high flux alarms and scram signals. A slight' increase-in the frequency of spurious signals has ' occurred since the previous month, the range for various channels now showing four per shif t to two per. day. Normal mode of operation for the power range nuclear instrumentation requires that a high flux level scram signal occur.simultanecusly on any two of these three channels while operating on a coincidence circuit. The' occurrence of two scram signals ~
on channels-6, 7 or 8 at the same instant will therefore cause plant shutdown by scramming-the reactor and tripping the turbine throttle valves closed.
The cause of the spurious signals. is not entirely clear but may be due to a o-gradual deterioration of' the ion :hamber detectors.
. Investigation of decontamination agents and procedures progressed during the month by performing certain radiochemical analysis on the test specimens removed from the walls of the shield tank cavity. Silver 110-m was determined to be the principal source of activity. Laboratory testing of decontamination agents resulted in excellent success being achieved with an alkaline-cyanide jell material prepared by a decontamination agent manufacturer.-
Main steam line vibration investigation also continued throughout '
the month with accumulation of data during periods of load change. A planned program to understand the problem and eliminate the cause has now been out-lined and initiated.
Plant Shutdowns
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Shutdown No. 52-2-h 11/h/62 - A 7. hour shutdown for minor main-q tenance and remova'l of test spec-(/
'imens from the shield tank cavity ~
walls.
No recotor scrans occurred during November.
Maintenance Following is a sumnary of major activities carried out by plant naintenance personnel during November.
1.
Two stainless steel pl-cest specimens were removed from the shield tank cavity aalls for purposes of contamination
-analysis.
, 2.. Completed'the rebuilding of the main coolant system bleed' sampling line.
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3 ;, Replaced defective rod position indicating coils on No. 10 control rod drive mechanism.
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Adjusted the motor operator on the pressurizer solenoid relief isolation valve for proper operation.
5 Installed a new steam line to the evaporator reboiler pump in order to make possible the removal of concentrated boric acid mixes from the pump.
6.
Repaired two oil leaks in the turbine control oil system.
7.
Overhauled No. 1 heater drain pump due to inability to pump at rated capacity. Installed a new seal ring and lower bearing, fabricated and installed a new oversized collet and (v) trued up the. impeller inside diameter.
8.
Installed new bearings in No.1 cravity drain tarJ: pump and built up journals by spray welding.
9.
Overhauled No. 1 and No. 2 control air compressors. Installed a new head on No.1 unit and new rings in No. 2.
3 10 Completed the installation of the vapor container rain deflector.
(b Started installing the safety injection tank rain skirts.
- 11. Exterior construction of the potentially contaminated area storage building was completed and the interior concrete floor poured.
- 12. Completed post-refueling cleanup and repainting of the machine O
shop. Work continued on decontamination of handling fixtures V
used during the refueling period.
Reactor Plant Ferformance Performance of five-wire in-core instrumentation runs were continued throughout the period. These data were prepared and run through the IEES computer code, a typical result showing the following:
Rod Positions: Groups 6, h, 2 @ 90", 3 @ 55 7/8" Core Average Power: -538 int Fq = 3.6; Minimum Q-DNER = 3.5 FA H = 2.5; Ctidlant Temperature at outlet of hot channel = 590 F During the plant shutdown period, tempe:'ature coefficient data atpeakxenonpoisoningwasobtgined. Analysis of this data showed a temper-ature coefficient of -2.h x 10~ M / F at $13 F.
Power coefficient measure-n()
ments at $h0 Wt were also made prior to the shutdown, but this data has not yet been analyzed.
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7U A gradual increase in core reactivity was noted to occur after reaching equil'brium ze ton at $h0 }fdt, following the plant shutdown period.
The gain reached a maximum of approximately 0.35% 6(0 one week after return to power. The gain in reactivity has remained constant at approx-imately 0.3% d burnup requirements.
(O level, while control rod withdrawal was that expected for normal fuel Turbine Plant Performance Steam line vibration measurements'were continued during the month.
Preliminary analysis of this data indicates that the stresses induced by the cyclic vibrations are well below those levels required for possible fatigue failure and that the driving force is very likely due to both pressure and flow oscillations from the steam generators. Investigation
/q f this problem continues based on a program resulting from a recent meeting V
held with representatives of a pipe hanger manufacturer and Stone & Webster Engineering Corp.
A measurement of feedwater heater terminal temperature differences at 169 MWe and 1.3 inches of Hg. condenser backpressure with an average main coolant temperature of $1h F continues to show No.1 and No. 2 heaters operating at higher than design values. -No. 3 heater is now performing within its design terminal temperature difference value.
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Work was begun on a secondary plant performanco study to deter-mine the feasibility of operating the plant with two rather than three condensate pumps in service. This analysis includes transient as well as steady state conditions and considers such factors as net positive suction head, flow and pressure distributions.
Collection of plant calorimetric data and analysis of condenser performance data has continued throughout the period.
Chemistry Main coolant oxygen levels remained low throughout the month with concentrations ranging from undetectable to 80 ppb. M activitymeasurementsaveragedapproxinately1.5x10gincoolantspecificJic/ml while coolan crud levels remained low at approximately 90 ppb. A typical crud specific activity measurement indicated the following:
Mn - $h 2.1 x 1 dpm/mg Cr - 51 2.h x 10 dpm/mg Ag - 110m 2.9_x 1 dpm/mg Fe - 59 2.h x 1 dpm/mg Co - 58 3.0 x 1 dpm/mg Co - 60 6.1 x 1 dpm/mg O
Trace concentrations of 0.5 ppm boron were measured at times during the period.
V
.,,U 8.0 x 10-3 nc/ml, with a high value of 1.5 x 10 ged to average aboutEc/ml occurring after The main coolant I-131 activity contin plant startup on November 5. The I-131/I-133 atomic ratio averaged 3.6 for the period, increased to 7.0 shortly after plant startup and was noted to be 3.6 at the end of the month.
Main coolant fission product level neasurements continued to ahow higher values than those recorded during Core I operation. Results af a typical fission gas analysis showed levels as follows:
Xe - 135 5.7 x 10-1 nc/ccgas 23 pc/cc ga.s Xe - 133 1
h.0 x 10 1 pe/ccgas Kr - 85 m 9.5 x 10- nc/cc gas A - kl p
V This recent increase in fission gas levels has placed an added emphasis on the waste gas handling and storage systems but no problem.s are, however, anticipated in the staring or release of the gas. A typical waste gas system analysis showed the following levels to exist:
2 5.1 x 10 1 pc/cc Xe-133 Gas Surge Drum 1.8 x 10 2 pc/cc Ie-133 Gas Decay Drum #2 h,-
Gas Decay Drum #3 6.5 x 10- pc/cc Xe-133 The specific activity of the spent fuel pit water averaged 2.7 x 10-3 Considerable effort was directed toward the study and investigation of decontamination procedures and materials during the month. An inventory was made of all contaminated parts available for decontamination studies; a (V) nnber of items were prepared for innersion in the spent fuel pit water; and
- .rious decontanination and protective coating materials were ordered in sample quantities from manufacturers. The najor effort, however, was confined to the problem of determining the nature of and finding ways and means of removing the contamination from the shield tank cavity surfaces.
Two test sections were removed from the cavity walls to aid in the overall solution to the contamination problem.
A specimen taken from one of the test sections was dissolved and a radiochemical separation and analysis made for Ag-110m, Co-60, Co-58, Mn-$h, Fe-$9, and Cr-51. The only activity found was that from Ag-110m with other separated fractions yielding background spectrums. Based on the specimen sise, it was indicated that the activity on the cavity liner is greater than 99.7% Ag-110m with no evidence of deposited crud.
Analysis of two specimens, one taken from each test section removed from the cavity walls, was performed in an attempt to determine the amount f]
of activity and its contributien to the total radiation dose being experienced in the shield tank cavity. In general, analysis of the data has shown that the activity on the backside of the steel lining plate contributes little to the total cavity dose.
. L.J' Investigation and test of various decontamination agents has, to date, shown an alkaline cyanide jell material, prepared by one of the manufacturers of decontaminating agents, to be the most promising.
Laboratory tests using this material on ten specimens taken from the shield tank cavity walls indicated that the average activity removed was approx-imately 96%.
Health and Safety Liquid waste with a total activity of 0.7h nillicuries was discharged from the plant during November. One hundred fifty-six drums of solid waste containing 598 millicuries were shipped for off-site disposal while $6 barrels of solid waste centaining hh0 millicuries were drummed.
Waste gas containing Ih.7 curies was also discharged from the plant during the period. At all times the concentration of waste products discharged nC from the site was well below the maximum permissible.
A plant site survey for neutron and gamma levels was performed at a plant load of 165 MWe. The recorded levels were well within the range of previous surveys.
General radiation levels in the shield tank cavity during the plant shutdown period were 100-250mr/hr. Measurements made near the hq
-cavity walls were as follows:
North and northwest wall (corner) -
5feetabovefloor~-300mr/hr
- Northeast wall (center) 5 feet above floor ~ - h00 mr/hr 5 feet above floor ~- 170 nr/hr East wall (center)
East and northeast wall (corner) 5 feet above floor - 900 mr/hr South wall (center) 5 feet above floor - 200 mr/hr
.5 feet above floora-230mr/hr West wall (center) h West wall (center) 11 feet above floor ~~ 90mr/hr J
- Test section removed from this location The radiation level on the charging floor over the edge of the cavity was 25-h0 mr/hr while at the barrier around the edge of the cavity, reduced 'evels of 10-30 mr/hr were recorded. General area radiation levels in the main coolant loop compartments were 100-300 nr/hr at a time approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after plant shutdown. Contamination levels on the charging floor at the end of the shutdown period were 15,000 to h0,000 2
dpm/ft,
A survey of pe spent fuel area showed contamination levels of 2,000 to 20,000 dpm/ft. Theentireareaaroundghepitwasmoppedresulting in levels being reduced to less than 2,00C dpm/ft. Radiation levels were 5-15 mr/hr in the general area, 25 mr/hr over the edge of the pit, h0-50 mr/hr in the area of the jacking pump and 500 mr/hr on contact with the filter box of the skimmer pump.
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,.U Personnel exposures as measured by film badges for the month of October, 1962 were as follows:
85 mr Average for all station personnel 700 mr Maximum individual exposure Continuous monitoring of off-site airborne activity during Novem-ber indicated lovels consistent with pre-operational values.
Design Changes One change in plant design was completed during November. This modification consisted of a piping revision to the main coolant bleed line sample line in the primary auxiliary building sample room. The sample line gs trip valve and manually operated root valve were relocated to a position d
adjacent to the point of take-off from the bleed line and existing sample
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piping was replaced with tubing of a smaller diameter. Installation of the new tubing was made in a way to minimize piping bends and traps, thereby keeping to a minimum the buildup of boron contamination in the sample line.
. Plant Operations Attached is a summary of plant operation statistics for the month n(j of November 1962, and a plot of daily average plant load for the same period.
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o IANKEE A'IOMIC EIECTRIC COMPANI - OPERATDIO -
SUMMARY
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NOVEMBER 1%2 EIEC'IRICAL MONTH YEAR _
TO DATE Gross Generation KWH 11h,829,900 61h,h8h,600 1,575,831,900-Sta. Service (While Gen. Incl. Losses)
KWH 7,167,795~
h5,6h3,616 123,175,698 Not Generation KWH 107,662,105 568,8h0,98h 1,h52,656,202 Station Service 6.2h 7.h2 7.82 Sta. Service (While Not Gen. Incl. Losses)
KWH h3,02h 3,877,120 13,968,838 Ave. Gen. 'For Month (720 HR.)
KW 159,h86 Ave. Gen. Running (713 HR.)
KW 161,052 PIANT PERFWMANCE Net Plant Efficiency 29.27 28.87 Net Plant Heat Rate Btu /KWH 11,659 11,823 Ibs. SteaOt KWI 13.91 1h.02 Circulating Water Inlet Temp.
Maximum F
hh Minimum F
36 Plant Operating Factor 9h.59 h9.83 59.98 NUCIEAR MONTH CORE II TO DATE Times Critical 0
27 289 Hours Critical HRS 720 17h5.52 lb,992.95 4
Times Scramed 0
2 32 Equivalent Reactor Hours @ $h0 K4t HRS 681.1 1h67.2 9,217.0 Average Burnup of Core MID/mtU 736.8 1537.2 Control Rod Position at Month End Equilibrium at 169.5 K4e Group 1 Rods out-inches O
Group 2 90 Group 3 69 0/8 m
Group h 90 i
Group $
0 Group 6 90
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