ML19351E022
| ML19351E022 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 09/30/1965 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| References | |
| NUDOCS 8011250443 | |
| Download: ML19351E022 (13) | |
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di.le c #E YANKEE NUCLEAR POWER STATION l
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<f OPERATION REPORT NO. 56 For the month of AUGUST 1965 i
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Submitted by YANKEE ATOMIC ELETRIC COMPANY Boston Massachusetts September 30,196$
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This report covers the operation of the Yankee Atomic Electric
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Company plant at Rowe, Massachusetts for the month of August 1%$.
Nj At +he beginning of the reporting period the plant was operating at a power level of 108 We.
A loss of 10 We in generation capability was measured on August 7 when the number three loop main coolant pump was shutdown as a part of a core noise measurement program being performed by the vendor. The plant continued in three loop operation and at Oh30 on August 9th a load reduction commenced.
The turbine generator unit was taken off the line at 0600 for the annual refueling and maintenance shutdown. This ended a continuous power run which extended from March $ to August 9, a total of 3857 consecutive hours of power generation. The retetor had been critical since February 13, a total of h25h consecutive hours. Also, the primary plant had been at temperature and pressure since September 6,1%h, which was the start of Core IV operation.
n Total electric generation for Core IV was 1,309,058,800 KWh.
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During this period the reactor availability factor was 99 7h% el the overall plant operating factor was 89.77%, including the " stretch operation" period when full rated capability was not possible. During this period of over 8000 hours0.0926 days <br />2.222 hours <br />0.0132 weeks <br />0.00304 months <br />, the turbine generator was off the line for all causes a total of less than 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.
The effort during the first week was concentrated on the T secondary plant, as the reactor plant was involved with AH: operator J examinations, end of life physics tests, and core noise measurements.
v After the plant was cooled down and depressurized, a leak rate test was performed on the vapor container. Four portable air compressors charged 2500 scfm of air for about fourteen hours to raise the vapor container pressure to approximately 22.5 psig. Measurements were made during the ensuing four days to determine the vapor container leak rate. On the fourth day a combination leak rate including the air p
lost through a calibrated orifice was measured. During the test period, v
soap bubble tests were performed upon all non-welded penetrations.
Seventeen minor leaks of the slow bubble type were located in the more than 2h0 penetrations tested. None of the leaks were large enough to be measured. All of the leaks were noted and will be repaired as time pers::its with the vapor container depressurized. The vapor container was depressurized by bleeding the air through the purge fans and out the primary vent stack to atmosphere.
Preliminary results indicate a leak rate of less than eight lbs./hr., which corresponds to about 0.1%/ day of the confined air in the container at 22 psig.
The test was completed on August 18.
The effort of the next week was concentrated upon stripping the reactor vessel head in preparation for head removal and shield tank cavity flooding. Again, as in previous refuelings, the welded seams of the shield tank cavity were visually examined for potential leak points p and approximately 10 to 15 pinholes were found and welded.
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Increased radiation levels around the vessel head in close proximity to the control rod drive mechanisms dictated the placement of lead shielding prior to stud removal operations. Various flushing operations did not reduce the radiation levels appreciably in the control rod drive area but were quite successful in the pressurizer area and in various lines and drains where crud had accumulated in other parts of the system. Generally, radiation levels in low velocity zones such as the control rod drives, were three to five times previous refueling levels.
After head removal, a radiation reduction test was made by inserting a water jet into a control rod housing to flush the mechanism.
The flushing of the housing appeared to be successful, but too much time and radiation exposure was consumed to continue using the test probe on a single housing basis. A device with 2h spray no zles will be fabricated to flush all mechanisms at once with the head outside the vapor container.
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%r The empty, ten-element, spent fuel cask was received at the plant, reloaded, and shipped out with the second load of spent fuel.
A decision was made to remove the core barrel assembly and broken irradiation spacimen holdero, to inspect the upper flange welding of the lower core support barrel, and to install the secondary core 8supportstructures.
The core barrel assembly consists of:
the lower core support barrel, the core barrel, the lower core support plate, and the control rod shroud tubes. This assembly had been in place since original installation.
This core barrel assembly removal required the complete removal of all fuel from the reactor vessel. While removing #'el, and after nearly all the fuel had been removed, an irradiation specimen
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was seen ir. the lowcJ nozzle of a fuel assembly. The remaining fuel
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was then examined more closely before being sent to the spent fuel pit.
A total of three irradiation specimenc and three pieces of wire, believed to be miscing irradiation specimen holder plug bails, were located in the remaining fuel assemblies as they were removed from the core.
Af ter the fuel removal, a program of control rod inspection was instituted before an attempt to remove the core barrel assembly.
After inspecting the third control rod, reinsertion through the lower core support plate met with resistance. A close look determined that the west source vane had been picked up with an adjoining fuel assembly and had fallen across the lower core support plate as the fuel was removed. The source tubes had separated frca the vane due to shearing failure of the five cap screws which secure the tubes to the vane.
At the end of the reporting period, most of the source tubes (s and the source vane had been removed with no evidence of source tube f
clad failure having occurred and inspection of the control rods and shim rods was continuing.
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The secondary side of the four steam generators were opened and the hangers on the feedwater distribution rings were found to be fractured. A repair procedure from the manufacturer has been requested.
Plant Shutdowns Shutdown No. 79-h-8 8-9-65 Scheduled Core IV - Core V refueling shutdown.
Plant Fhintenance The followir.g is a summary of the major activities performed by the maintenance staff furing the month of Au;ust.
1.
Nbde temporary repairs to a 1" crack in the valve block on the pressure side of number 1 charging pump. A 7']
thorough examination is scheduled later in the shutdown.
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Installed new bearings and seals on number 2 purification pump. The seals had leaked water onto the motor, causing it to trip out on overload on August 3 3
Installed new seals on the shutdoan cooling pump and realigned the pump and mater.
9 h.
Removed the main steam line safety valves, which are to be pressure tested.
5 Cleaned the tubes on the main condenser and main trans-former oil coolers.
6.
Stripped the high pressure and low pressure turbines for inspection. New seal calking strips were installed.
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Magnaflux inspected various turbine parts.
7 Replaced connectors and inspected oil circuit breakers and transformers in the outside svitchyard.
8.
Installed a new dispatcher phone which operates on a ccrrier current on one phase of the 115 KI line.
Circuit tuning is still in progress.
Chemistry The main coolant feed apl bleed and purification systems were run at 50 gpm and 60 gpm respectively before the shutdown and reduced the system crud level from l$ ppm to less than 1 ppm prior to system cooldown. At the lower crud levels the coolant average beta-gamma activity (less tritium) was h.5 x 10-2 pc/ml. The coolant purification
[, system reduced the I-131 specific activity from 1.8 x 10-h pc/ml to 15 x 10-5 pc/ml. The average beta-gamma activity (less tritium) i 3' in the #3 steam generator (secondary side) was also reduced to x
1.6 x 10-7 pc/ml as a result of the lower main coolant activity.
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The water condition in'the spent fuel pit prior to shutdown' v
was as follows:
pH 6.5 beta-gamma activity (less tritium) 6.7 x 10-3 c/ml p
i-conductivity 1.8 y mhos boron 79 ppm The #2 mixed bed demineralizer was borated at 2000 ppm and cycled in NH -B0. However, it soon developed that the series filter h
3 in #h rosition bBeame plugged. Both units were removed from service i
and purification was then run through #1 cation demineralizer with a new filter in the #h position. Further investigation is required to determine the exact problem with #2 demineralizer.
i After cooldown, main coolant oxygen levels increased to
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180 ppb and the coolant average beta-gamma activity (less tritium) decreaeed from 1.6 x 10-2 ve/m1 to 8.6 x 10-3 ve/m1.
Cred 1 eve 1s varied between 1.6 ppm and 17 ppm.
Ammonia was maintained in the main coolant and the shutdown cooling watu until the reactor head was removed and the shield tank cavity was flooded. The water had a very dirty appearance, which was much worse than previous shutdowns from a neutral pH condition. Two
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. filter units were placed in service in an attempt to clear the water j
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.for refueling visibility. At the end of the period the water still i
had not cleared to previaus refueling levels, but was c-ntinuing to l
improve.
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During this period, the system crud level decreased from 1.2 ppm to 0.h0 ppm.- The coolact average beta-gamma activity (less tritium) varied between 1.0 x 10-2 pc/ml and h.1 x 10-3 pc/ml. The primary soluble nuclides were Mn-514 and Co-58.
Radiochemical analysis for crud samples collected during L
this period are incomplete.
Reactor Plant Perfor"ance i
End of Core IV physics testing began af ter shutdown and continued through August 11.
The program consisted of the following i,6#s: temperatute coefficient measurements at 5200F; Group A control rod differential and integral worth; and, all rods out, xenon free, boron concentration.
The results of this test program are not completely analyzed at this time.
A total of seven fuel assemblies were inspected. Four were 4
pre-selected and three were randomly selected. All the fuel assa.nblies i
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appeared in excellent mechanical condition but the following abnor-malities were noted:
1.
A heavy black crud deposit was observed on all assemblies.
The crud pattern and amount of crud appeared to be related to expected heat flr.
That is, the higher heat flux portion of the core generally had the heaviest crud deposit.
2.
Several pieces of foreign material were found in the lower section of some of the fuel assemblies inspected. Most of the fuel had already been removed from the core when these items were found but all fuel will be closely inspected especially that fuel to be returned to Core V.
The objects found have been identified as various portions of vessel irradiation capsules which broke loose in 1963 I
The high burnup assembly, A8, with approximately 30,135 MWD /MIU, which was cycled in Cores I, II and IV was one of the pre-selected assemblies inspected. It appearea to be in excellent condition except for crud deposits.
At the end of the period, inspection of shim and control rods had just begun.
Evidence of four sets of wear bands corresponding to S This would tend to indicate that the new Core IV sq the four rod heights during " stretch" operation was observed on the control rods and one set of deep wear marks was observed on the shim rod.
not reduced the amount of wear on the control rods.
Turbine Plant Performance The high pressure and low pressure turbines were disassembled
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for inspection. The water cutting of the last stage of the low pressere
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turbine was not as severe as last year; however, about 100 blades in
'x-the seventh and last rows are scheduled to be restellited where the stellite is eroded to the blade.
Both the high pressure and low gessure spindles were electro-magnetically tested with no cracks or flaws being noted.
The high pressure and low pressure stationary blade rings are to nave new seal strips installed.
A monel calking strip will be used.
The seal strip between rows 3-h, h-5, and 5-6 of both ends of the low pressure spindle will be recalked with the original sof t iron material. The blade rings will be chamfered at the eroded area at the steam seal and filled with weld deposit stainless steel.
The three sets of turning vanes in the inlets of the moisture separators need rebuilding or renewal. Availability of parts will determine the action to be taken.
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- o e Instrumentation and Control The following is a summary of major activities carried out by the plant Instrumentation and Control staff during August:
1.
Installed new loop seal level alarms in the waste gas system.
2.
Completed preventive maintenance on the control room instruments.
3 Installed a new differential pressure indicator across the',ification ion exchanger and filter. The new indic. tor is 0 to 60 psig as compared to the old one of n
0 to 200 psig.
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Installed the temporary refueling nuclear instrumentation in the control room.
5.
Recalibrated the feedwater flow systems.
6.
Replaced the coaxial jumper cables to the ion chambs.rs
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in thimbles 3 and 7 i
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Replaced the CIC and UIC in thimble 7 with rebuilt detectors.
8.
Relocated the manipulator tool telescope alarm box.
9 Checked the vapor container high pressure relays for l
proper valve closure at $ psig during the air charge to container.
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Installed 5 new air temperature detectors and two relative humidity detectors in the vapor container.
11.
Pulled in two new triaxial cables in thimbles 1 and h.
12.
Installed a main coolant level detector used during refuelings.
Health and Safety During the month of August 1965, no drums of rmdioactive material were prepared nor were any drums shipped off site for disposal.
$$,3h6 gallons of liquid waste containing a gross beta-gamma activity of 0.18 me and 125 22 curies of tritium were discharged during
('N August. Gaseous waste containing a gross beta-gamma activity of t
j h98 5 me and h.9 curies of tritium were discharged during the same period.
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- In addition to the above,138 curies of airborne tritium i
was discharged during the-vapor container depressurization.
- Also, 282 me of airborne tritium was released from the spent fuel pit exhaust fan during the month.
Ten spent fuel assemblies with a total activity of.32 megacuries were shipped off site for reprocessing.
2 Radiation and contamination levels on the empty ten element cask as it was received-on the site were as follows:
Radiation ove. the open top, 2 mr/hr; two feet inside cask, 15 mr/hr; top of basket, 30 mr/hr; 1 foot inside basket, h0 mr/hr.
Contamination-outside cask, 50-150 dpm/100 cm2 m -
After loading the cask and two washings for decontamination, the following levels were measured:
Radiation
- contact, outside, no detectable gamma levels above background (.h to.7 mr/hr) also, no detectable neutron radiation.
Contamination-outside cask, 100-900 dpm/100 cm, generally.
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l Results of tritium analysis performed by an outside laboratory on samples taken on 8/6/65 were as follows:
Tritium Activity Iocation (yc/ml)
Ion exchange pit (5.0 +.h) x 10-h l
Main coolant 1.2h,+.05
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The following radiation levels were measured about 56 hours6.481481e-4 days <br />0.0156 hours <br />9.259259e-5 weeks <br />2.1308e-5 months <br /> after reactor shutdown:
Location Radiation Dose Rate Pressurizer general area 300 - 400 mr/hr-heater bundles 100 - 700 mr/hr level cell 10 r/hr Number 3 steam generator main coolant inlet 270 mr/hr tube sheet level 80 - 260 mr/hr manway area 0.h mr/hr steam line 0.h mr/hr i
drain valve 1-3 r/hr i
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- s 7-is Icop Area 01
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- h general area 35-90 mr/hr 65-150 mr/hr 65-70 mr/hr 35 mr/hr hot leg piping 150 mr/hr 150 mr/hr 500 mr/hr cold leg piping 150 mr/hr 180 mr/hr 120 mr/hr 120 mr/hr cold leg stop valve 120 mr/hr 310 mr/hr 130 mr/hr 180 mr/hr drain valve 2 5 r/hr 3.5 r/hr 3 r/hr 220 mr/hr (after flush)
Charging Floor Area General area 0.2 to 0.4 nr/hr and 2 5 to 3 mr/hr at shield tank cavity edge, (m)
In an attempt to reduce radiation levels in the area of the control rod drive mechanisms, the water level was raised and lowered as quickly as possible in the vessel. Thirteen cycles reduced the levels from about 225 mr/hr to about 175 mr/hr. Maximum hot spots still remained in the range of 3-5 r/hr.
The next step was to hang 1" thick sheets of lead from the lower Shalfoftheairbaffle,thusshieldingthestudareafromthehead.
This reduced the radiation levels by about a factor of 10 to 15-50 mt.'5r.
A radiation survey taken on 8/25/65 of the feed and bleed heat exchanger showed: 35-h0 mr/hr at the entrance of the cubicle,100 mr/hr general area,150 mr/hr on the charging line, h25 mr/hr on the bleed line, and h20 mr/hr on the bottom of the heat exchanger.
After the reactor head was removed from the vapor container, t,he radiation level was measured at 350 mr/hr two feet inside the inner d
edge of the flange.
Yankee plant :ersonnel radiation exposures as measured by film badge for the month of Aucust 1965 were:
Yankee Personnel Average
- 263 mrem Maximum individual exposure - 700 mrem N.E. Pcwer Service Co. Personnel Average
- 387 mrem Maximum individual exposure - 660 mrem ex Plant Operations l
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l Attached is a summary of plant operation statistics for the
' month of August 1965 and a plot of daily average load for the same period.
The following errors have been found in the June and July 1965 operating summary under Station Service, as follows:
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e JUNE 1965 Reported As MONTH YEAR TO DATE Gross Generation IMI 92,h23,000 717,129,600 h,680,2h$,800 Sta. Ser. (while gen. incl. losses)
IMI 6,603,600 h5,05h,h80 32h,716,589 Net Generation K4H 85,819,h00 672,07$,120 h,355,529,211 Station Service 7 1h 6.28
- 6. 9h Corrected To Gross Generation KdH 92,h23,000 717,129,600 h,680,2h$,800 Sta. Ser. (while gen. incl. losses)
Kdli 7,023,h01 h$,h7h,281 325,136,390 Net Generation WH 85,309,$99 671,6$$,319 h,35S,109,h10 Station Service 7.60 6.3h 6 95 JULY 1965 8
Reported As m
KdH 89,h30 300 806,559,900 h,769,676,100 Gross Generation 3
Sta. 3er. (while gen. incl. losses)
KdH 6,790,200
$3,8hh,680 331,506,789 WH 82,6ho,100 7$h,715,22 h,h38,169,311 Net Generation Station Service 7.59 6.h) o.95 Corrected To KdH 89,h30,300 806,559,900 h,769,676,100 Gross Generation Stn. Ser. (while gen. incl. losses)
K4H 7,189,132
$2,663,h13 332,325,$22 KdH 82,2hl,168 753,896,h87 h,h37,350,$78 Net Generation Station Service 8.0h 6.53 6.97
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9 YANKEE ATOMIC ELECTRIC COMPANY -- OPERATING SUle(ARY AUGUST 1965 i
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EIRCTRICAL MOMPH YEAR Gross Generation WH 20,i/3,100 826,833,000 h,789,9h9,200 Sta. Service (While Gen. Incl. Losses)
WH 1,836,570 5h,h99,983 33h,162. 092 Net Generation WH 18,h36,530 772,333,017 h,b55,787 108 98 9 06 6.59 c
Station Service Sta. Service (While Not Gen. Incl. Iosses)
WH 739,963 895,899 20,69h,33J Ave. Gen. For Month (7hh IES)
KW 27,2h9 Ave. Gen. Running (198IES)
W 102,389 PIANT PERFCRMANCE Net Plant Efficiency 2h.70 28.11 Net Plant Heat Rate Btu /WH 13,817 12,lhl i
Lbs. Steam / Net WH g
Circulating Water Inlet Temp.
0F 65 Navi =m Mi ni --
F 50 Plant Operating Factor 16.79 78.63 70.67 Reactor Plant Availability h3 01 92.50 83.17 NUCLEAR MONTH CORE IV TO DATE 12 32 357 Times Critical Hours Critical HRS 257.65 8160.27, 35,960 96 0
S 49 Times Scrammed Equivalent Ren er Hours @ 600 Wt HRS 12h.38 72h8.hll 26,159.0h WD/mtU Average Burnup of Core 2
Control Rod Position at Month Ehd Equilibrium at
- RHlION MONTH TOTAL BUMTUP Group A N a out-inches INNER 1h6.58 18,07h.68 Group I MIDDLE 177 7h 15,5hl.81 Group C OUrfR 122.30 6,759 10 Group D E-6 136.28 30,136.16 1 Minor correction for end of core Boron es 2000 ppm 2 Shutdown for refueling
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YANKEE ATOMIC ELECTRIC COMPANY DAILY AVERAGE LOAD for AUGUST 1965 150 -
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CORE IV REION IDCATIONS t
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