ML19351E146
| ML19351E146 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 07/31/1963 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| References | |
| NUDOCS 8011250662 | |
| Download: ML19351E146 (9) | |
Text
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O YANKEE NUCLEAR POWER STATION OPERATION REFORT NO. 30 For the month of JUNE 1963 fpj.]Qg
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O Submi.tted by YANKEE ATOMIC ELECTRIC COMPANY Boston Ihssachusetts July 31,1%3 l
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3 g(j This report covers the operation of the Yankee Atomic Electric Company plant at Rowe, Massachusetts for the month of June 1963.
At the beginning of the period the plant was operating at a 0
power level of 160 Mle and a main coolant average temperature of $07 F.
Continuation of the core extension program remained in effect with reactiv-ity added through gradual reductions in main coolant temperature and station load to compensate for reactivity lost through burnup.
On June h a reactor scram from a power level of 157 Mie was experienced.
Riintenance work in the switchyard of the Harrimin hydro-electric station up stream of the Yankee plant was in progress at the time of the scram. A flashover occurred betteen the out of service line and Z-126 line which runs between Harriman and the Yankee plant causirg Z-126 to ground. The resulting line fault caused the Yankee Z-126 oil circuit breakers ard the hydro station oil circuit breakers to open automatically, de-energizing the line and with it the station 2hCO volt bus No. 2.
During these operations the station scrammed automatically.
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With Z-126 line de-energized plant station service reverted to Z-177 line fed from a downstream station. In this manner 2h00 volt bus No. 3 remained in service and tie breakers were closed to energize No.1 bus.
However, due to the increased demand on Z-177 line, line voltage dropped and minor difficulties were experienced in initial attempts to restore some equipment to service.
O The plant was placed on hot standby until full line voltage was restored following which the reactor was brought critical by means of programmed rod withdrawal.
l Follcwing the critical approach main steam pressure was raised l
and steam admitted to the turbine. Immediately on turbine roll off a second reactor scram occurred. The,:ause of the scram was traced to a pressure switch on the first stage shell drain of the turbine. The switch
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is tied to the red scram breakers through an agastat relay and is left N
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open at power levels below 15 Mie due to the increased flow through the shell drain. However, a trap bypass valve downstream of the pressure gage tap which is normally open during roll off was inadvertently lef t in the closed position thereby causing a pressure surge ccrdition and actuation of the pressure switch.
Follcwing the scram the reactor was again brought critical and the trap bypass valved opened. Turbine roll off was accomplished smoothly, the generator phased to the line and plant load raised to lh8 Mie.
For the remainder of the month plant electrical output continued to drif t downward following main coolant tempere ture. At the end of the reporting period the plant was cperating at a p;wer level of 133 Mie and a main ecclant average temperature of h890F witn all rods ?t the fully withdra.Ti position of 88 7 '.ches.
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Daring the pericd a test was performed with No.1 feedwater heater valved out of service to determine its effect on plant electrical eutput.
The increase in load was slight and the heater was retrened to service. A more detailed description of the test can be fcund in the Turbine Plant Performance section of this report.
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On June 18 a vapor container inspection was made and no abnormal conditions found.-
During June threeCore I spent assemblies were - shipped off site for inspection and examination under an A.E.C. contract.
Ten new fuel assemblies were delivered to the plant in June. A total of 72 new fuel assemblies are now in storage at the site.
Two inconel clad silver-indium-cadmium control rods to be utilized in Core III operation were delivered to the site in' June.
Plant Shutdewns Shutdown No. 60-2-12 6/h/63 A 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> shutdown resulting from a reactor scram.
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Reactor Scrams Scram No. 36-2 6 6A/63 An automatic reactor scram from a power level of 157 We.
The reactor scrammed due to loss of an outside transmission line.
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Scram No. 37-2-5 6A/63
_ A reactor scram from a power level of < 1 Et. The reactor scrammed due to a pressure surge in the first stage shell drain of the turbine.
Maintenance l
(O Following is a summary o. major activities carried out tr phnt maintenance personnel during June-1.
An ion exchange tank was -loaded with resin and installed in the ion exchange pit.
- 2. lNew packing sleeves were installed in No. 2 component cooling water pump.
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Steam leaks from behind the bolt heads and nuts of the moisture separator flanges were reduced by installing copper washers.
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New air filters were installed on the exciter cooling system, f
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The drip covers of the service wate-pump motors were-removed
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air and resultant high motor temperatures.
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An inspection.of_ the four 2h00 volt air circuit breakers was conducted.
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The exciter brushes,were inspected and changed as found necessa/y.
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No.1 vapor container cooling water pump breaker was inspected.
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An inspection of the' unive,rsal hand!.ing tool was conducted.
.Cfhe.stry Throughout the _ reporting period main coolant oxygen levels remained below the point of detection.
Operations with ammonia in the main coolant system con.inued throughout.the month with NH3 concentrations ranging frem a low of 6 ppm to'a high of 12 ppm.
Following the reactor scram of June h main coolant crud levels increased to 2.5 ppm and then to h ppm after flushing the 5" loop bypass lines. Purification flow was increased resulting in improved filtration efficiency of the ion exchange resin and main coolant crud level was reduced to 0.50 ppm on June 6.
For_the remainder of the period main coolant cr"d levels ranged between 0.19 and 0 57 ppm.
n A typical main coolant crud analysis made during the period V
iidicated:
Fe - 59 2.9 x 1 dpm/mg Ag - 110m 5.3 x 1 dpm/mg Co - 60' 1.h x 1 dpm/mg Co - 3 5.8 x 1 dp'm/mg Cr - 51 6.9 x 1 dpm/mg Mn - 5h 8.5 x 10 dpm/mg nO A typical main coolant gas analysis made during the period indicated:
Xe - 135 0.11 pc/cc Ie - 133 1.70 pc/cc Kr - 85 m 0.38 pc/cc A marked decrease in the I-131 concentratio was yoted during the period with an average value measured at 7.h x 10- pc/.al. The redtiction was attributed to a decreased demand on the pa:.fication system and an increased flow through the anion bad.
Early in the period secondary side steam generator chloride concentrations began to slowly increase. Normal boiler chloride concen-tration is less than 0.1 ppm with _200 gallons per day per boiler blevdown.
.g On June 2 boiler chlorides reached.0.5 ppm with 2000 gallons per day (j
blowdown on each boiler. A continuous h000 gallon per day olowdown was initiated and chloride concentrations were reduced to 0.1 ppm on June 5.
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O-Investigations as to the cause of the increased chloride concentration revealed a lower than normal water makeup to the secondary system from the water treatment plant was occurring.
-A sodium test performed on the secondary side of the steam generators verified a 90 gallon per hour main condenser leak. A program of-increased blowdown was established.to limit
, chloride concentration to'_0.1 ppm until the condenser can be taken out of service-at the refueling shutdown.
During the month the secondary system feedwater ammonia concen-tration which is normally less than 0.1 ppm increased to 0.5 ppm. The increase was attributed to decicased main condenser vacuum with subsequent reduced efficiency in the air ejector intercondenser whose drains are returned to the main condenser. Frequent analysis of the feedwater for copper have since been made to determine if any corrosive attack was occurring to the-feedwater heater tubing. Should copper be detected in the feedwater, a change from hydrazine to sulfite for oxygen control will be initiated.
O Reactor Plant Performance During the return to power on June h all control rods were completely withdrawn to the upper program limit of 88 7/8 inches prior to generator phasing and reactivity requirements during generator loading-were satisfied by reduction of the average main coolant temperature and by 9
xenon burnout at power. A core reactivity loss of 0.08 % 6 9 (V
was observed following -recovery from the scram, which is approximately one third of.that experienced previously following a scram. However, this scram recovery differed from those previously in that operation with ammonia in the main coolant system was in progress. Also, due to'the core extension program, less control rod motion occurred during power operation prior to the scram.
In the period following the scram an essentially zero core depletion rate was established resulting in a steady reactor power n) corresponding to u 0.1 % 6/0 higher than would' have been expected b
from the core. depletion rate observed prior to the scram. From June lh through June 20'the core reactivity depletion rate was untform but the magnitude was approximately two thirds of that observed prior to the scram.
The reduced depletion rate resulted in a core reactivity gain of N O.15% 6 tc above the previously' established reference depletion cur:e. During the remainder of the month the depletion rate remained essentially constant at 0.015% 6 8 per week.
The following were determined by means of in-core instrumentation meas iments at a power level of h6h' Wt and all rods-at-the fully withdrawn posi.1on.of 88 7/8 inches:
Fq 2.6 2.8 FAT Minimum QDNBR _
3.6 Turbine Plant Perfo mance.
In an effort to increase the plant gross electrical output No.1 feedwater heater wcs temporarily removed from service. The Nt change
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observed;wasL the same as calculated, but because of the higher than normal--
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condenser inlet water temperatures and the instability of the circulating
-water system, the condenser back pressure increased by 0.3n Hg, and the
~ lectric. output increased by only 2 We..
The heiter was returned to service-
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e since more than one half of the expected We gain was absorbed in theLincrease
'of condenser back pressure and the remainder would have been lost when xenon poisoning reached equilibrium for the higher core power.
The results of-a recent *?edwater heater terminal difference measurement were Ih3 We @'2.3" Hg. Back Pressure
- 1 Heater 9F TD 0
- 2 Heater 13 F TD s
- 3 Heater 50F TD h% -2 heater is still net within the guaranteed performance.
1 Continued operational difficulties with the circulati_ng water
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. system were experienced during the month. Discussiocs with outside consulting serv 1ces have led to a redesign of the vent system to reduce-i hydraulic instability in the condenser discharge. Material procurement is now in progress and installation of a new vent header will be made during the refueling outage.
Instrumentation and Control Due to the reduced main coolant temperatures realized during the core extension program, the narrow range temperature channels were recalibrated to maintain main coolant temperature indication on scale.
i Health and Safety Liquid waste with a total activity of 0.1h ac was discharged from the plant during June. Gaseous waste due-primarily to radiochemistry sampling containing an estimated 200 me was discharged during the same period. At all times the concentration of waste products discharged from the site was well below the maximum permissible.
Eight drums of solid radioactive waste containing 366 sc were prepared during June. No drums.were shipped from the site.
Three Core I spent assemblies were shipped off site for exam-ination under an A.E.C.. contract. Maximam radiation levels measured on the cask prior to shipment were 2, 12 and Ih w /hr contact respectively.
2 Contamination levels were < 2000 dpa/ft. The results of a radiation survey of the yard decontamination pad'atter the final shipment.showed 5 mr/hr at one inch at the drain, and a. general area reading of 3 to 6 ne/hr~
at.one inch ~on the pad.
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. Sodium cyanide _ decontamination of the universal handling tool caused radiation levels to be reduced from 75 mr/hr to 35 mc/hr 'at one inch. Outside_ surface contamination 1 els were reduc'ed by a factor of -
L seventy to approximately 10,000 dpm/ft i
-A radiation survey of the vapor container pipe trench showed 1
general area levels to be 100-350 r/hr r ' 1-2 r/hr contact with the shield tank cavity fill and drain line.
l A radiation survey of the vapor container Loop fl following the scram of June h resulted'in the followirg:
Bypass valve.
5 r/hr contact Bypass loop - horizontal section
.200-300 mr/hr contact
_ Main coolant check valve 150 mr/hr contact Base of steam generator 600-1000 mr/hr contact l
Loop fl - general area 100-500 mr/hr o
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- Flushing of the bypass line resulted in a considerable reduction
.in the measured contact radiation levels.
, _ Personnel exposure for Yankee plant personnel as measured by film badges for the month of-June 1963 were:
33 mr/hr
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Average for all station personnel
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190 mr/hr 16r4=nm irdividual exposure
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Plant Operations
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Attached is a summary of plant operation statistics for the l --
month of June 1963, and.a plot of daily average plant load for the ""ne l
period.
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YANKEE ATOMIC ELECTRIC COMPANY - OPERATING
SUMMARY
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ELECTRICAL MONTH YEAR TO DATE l:
Gross Generation KWH 102,678,500 661,181,300 2,362,653,300 l
Sta. Service (while Gen. Incl. Losses)
KWH
'i,073,298 hl,815,922 172,572,h89 l
Net Generation KWH 95,605,202 619,365,378 2,190,080,811 Station Service
. 6.89 6.32 7 30 Sta. ' Service. (While-Not Gen. Incl. Losses)
KWH 32,700 997,h91-n,%6,329 Ave. Gen. For Month (720 HRS)
KW 1h2,609 Ave.' Gen. Running (713 95. HRS)
KW S3.317 PIANT PERFWMAN3 Net P'. ant Efficiency 27.hh 28.9h l
Net flant Heat Rate Btu /KWH 12,h37~
11,792 i
- %s. Steam / Net KWH u.87 L.06 Circulating Water Inlet Temp.
8 Maximum F
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Minimum F
60 l
Plant Operating Factor 5
89.6 91.2h 68.89 NUCLEAR MONTH
' CORE II TO DATE Times Critical 2
37 299 Hours Critical HRS 715.25 6766.67 2qpn.10 Times Scrammed 2
7.
37 Equivalent Reactor Hours @ $h0 MWt HRS 6h5.1 617h.0
%,091.1 Average Burnup of Core WD/mtU 697.9 6678.9 l
Control Rod Position at Month End l
Equilibrium at h5h Wt h88 F T avg.
l Group 1 Rods out-inches 88 7/8 Group 2 88 7/8 Group ;
88 7/8-
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Group h 88 7/8 l
Group 5 88 7/8 Group 6 88 7/8 I
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O YANKEE ATOMIC ELECTRIC COMPANY DAILY AVERAGE IDAD for JUNE 1%3 E
150 i
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100 1
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eo 50 a F5utdown No. 60-2-12 em h
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