ML19351E220
| ML19351E220 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 05/23/1966 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML19351E219 | List: |
| References | |
| NUDOCS 8011260223 | |
| Download: ML19351E220 (11) | |
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b YANKEE NUCLEAR PCWEP. STATION
IAY ? 4 1953 n OPERATION REPORT NO. 6h
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cn submitted by YANKEE ATOMIC ELETPlc COMPANY Boston M2ssachusetts May 23, 1966 Ot'O so n a60 SR3 uga
This repert cove s the operation of the Yank 3e Atomic Electric Company pJant at Rowe, Massachusetts, for the month of April,1966. At 4
the start of the period the plant was base loaded at 185 Mie. A plant shutdown was schedcled for April 6 to repair the leaking pressurizer safety valve.
(Operatien Report #o3 Maren,1956). An increase in the leakage rate advanced the shatdown and the plant was taken off the line at 21h8 hours en April L.
Primary plant cooldown began at that time and was com-pleted by 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> on April 5.
The high set pressurizer safety valve was dismantled and exam-ined with a representative of the manufacturer present.
The disc was slightly cut and was replaced. The low set safety valve was also dismantled and examined. The Stellate seat was badly cut as well as some cutting of the disc. The entire valve was removed and taken to the machina shop. The StelJtte f ace of th-seat was ground down to rencve the cut and refaced.
A new disc was installed and lapped in.
The valvo was re-assembled in the shop and leak tested using a dead-weight tester bofore the valve was re-installed on the pressurizer.
Whila repatrs were proceeding en the safety valves, a vapor con-tainer inspection was made. Indications of leakage around the bolted and gasketed flange cf the Icep cne check valve were noted. The loop was drained and tne valve cover removed. The bearing blocks, bushings and pivot pin were badly worn. The bearing blocks were loose in their slots and motion had causcd the wear. The motion of the blocks against the valve cover had caused the gasket to leak.
Repair was made by installing a ccmplete new disc assembly and weJding the new bearing blocks to the valse 4
body.
In acdition, a stop block was attached, by capscrews and tack welding, to the underside of the cover to prevent the bearing blocks from escaping in the event the welds failed and wear began again. The pumps in each loop were rua
.diviceally and a sonic inspection of each check valve was made by the manuf acturer, with no additional abnornalities noted.
Upon ecmpletion of the repair, the Icop was filled borated water.
Due to an at: pccket trat f or ms, within the u" tubes of the steam gen-
,-)1 erator, it is tmpossitle to completely fill an isolated loop.
After the N,
loop wes ver.ted ar.1 filled as mach as possible it was pressurized to 250 lbs.
to allow cperation :f tha main coc3 ant pump. The loop was cut into the main coelant systam and the pump cperated to drive the air out of the loop.
The displaced air ccllected under the vessel head, which in turn was vented via a heee and vent line to the inlet cf the Primary Auxiliary Building exhaust f an, which dis:Parges through the Primary Vent Stack.
Atoat 5 hcurs after the ecmpletion of this operaticn, water was noted on the flcor of the fan room. Further checking indicated that the water was contaminated. An analysis of the water showed that it contained 2300 ppm borcn, and a specific activity of 2.26 pc/ml.
S ears of the dried D
areas indicated that contamtnation levels were between 10) and 106 dpm/ft,
2 predominately CoS8 and Mn5h.
It was estimated that a total of 25 gallons had been spilled.
It was theorized that the 250 psi air vented from the vessel head attained a high enough velccity to carry entrapped water to the fan, although
'o during pr^vious ventings the 14" drain on the vent line had been adequate to Kv prevent this. The water pe.ed through the fan and leaked out of the duct-work onto the floor. A radiation survey of the vent line and ductwork indi-cated radiation levels of 10 to 70 mr/hr on horizontal runs and 10 to 25 mr/hr en vertical runs, on contact.
. 4 The fan room was posted as a contaminated area and decontamination work began which reduced contamination levels of the floor areas to less than 2
100 dpm/ft,
The vent line will be modified before it is used again for this purpose to prevent a recurance of this incident.
To correct completely the spurious " pips" that were appearing on the power range channels, the compensated and the uncompensated ion chambers in thimble 7 were replaced during the shutdown.
(Operations Report #63 March 1966). These detectors correspond to channel 5 and channel 6 respect-ively. Also, at this time, a new BF3 detector was installed in thimble 6 and will serve as a spare.
The bleed line motor operated sample valve, SA-10V-513, which has been inoperative since its installation at the last refueling, was made fully operative by repacking the stem with a different type of material.
C-)
Primary plant repairs were completed at 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> on April 7, and heat-up comnenced.
The reactor was critical at 101h hours on April 8 and heat-up completed and the generator phased at 1520 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.7836e-4 months <br />. The load was raised, with peuses for boron dilution, to 160 Mle and held until lhh5 hours on April 9, when the load was increased to 170 FWe.
At 1950 hours0.0226 days <br />0.542 hours <br />0.00322 weeks <br />7.41975e-4 months <br /> on April 10, the load was raised to 185 Fue and remained essentially at that level for the remainder of the period.
Following the plant heatup, an inspection was made within the vapor container to check the repaired equipment. All pressurizer safety valve welds and safety valve leakage, and loop 1 main coolant check valve repairs, were inspected with no adverse or abnormal ccndition being noted. Minor valve stem packing adjustments were made on several smaller manual valves.
The spent fuel shipment scheduled for last month and delayed by a
- "j rail strike, was made on April h.
The empty fuel cask was returned to the plant and another shipment of 10 spent fuel assemblies was made on April 22.
This latter shipm^nt is the sixth in the series and makes a total of 60 spent fuel assemblies sent directly to NFS for reprocessing.
Control rod pressure housing No. 21, which was removad from the reactor vessel head at the last refueling, (Operation Report #58, Oct. 1965) has been destructively tested. This housing was chosen because it indicated slight internal wear when ultrasonically tested at the shutdown and because its location in an outer row of pressure housings made removal relatively easy. The housing was shipped to Westinghouse for the actual testing. %e test progrsm consisted of a hydro-static test and a vertical sectionira of the housing to expose the internal surface for overall examination, c; emi-cal analysis of deposits and metallographic examination.
The results reported to us indicated the housing did not deform when subjected to a hydrostatic test pressure of 6000 psi.
_,x The internal surface exhibited minor signs of wear consistant with 3/0" control rod shaft steps. The depth of these marks was so slight that it could nc,t be measured and is considered to be insignificant.
s,'
_ Metallographic samples prepared from transverse sections exhibited a microstructure typical of stainless steel with an average grain diameter of from 0.05 to 0.10 mm.
No evidence of carbide precipitation was found. The overall results of the inspection were very favorable.
In the past, difficulty has been experienced in latching drive shafts to control rods following refueling. The drive shaft is hollow and has a rod running its full length which locks the latching fingers at the bottom. During the refueling operation, the universal handling tool grasps the upper end of a drive shaft and simultaneously pulls the internal rod to release the fingers at the botton.
!bdifications have buen made to the universal handling tool and to the drive shaf ts, but the problem has persisted.
Present thinking is that with a possible stack up of tolerences in a drive shaft, the universal handling tool was unable to withdraw the rod far enough to fully release the latch fingers.
)
The tool has been dismantled again this month with modifications 2
having been made that allow an increase of :1" in the pulling of a drive shaf t button to 1-15/16".
It is now hoped that thi.s modification will pre-vent delays in future refuehngs caused by these drive shfts.
The mcnthly control rod exercise was performed on April 27, with no abnormal operatien being noted. Voltage readings on the primary position indicators indicated that all rods returned to their starting points.
Plant Shutdowrs Shutdcvn No. 82-5-3 h-h-66 An 89 hour0.00103 days <br />0.0247 hours <br />1.471561e-4 weeks <br />3.38645e-5 months <br /> 32 minute forced shutdown to repair leaking pressurizer safety valves.
Plant Maintenance The follewing is a hst of major items performed by the plant maintenance staff daring the month of April,1%6.
Items performed during the shutdown include:
1.
Repair of pressurizer safety valves.
2.
Repair of main check valve in #1 loop.
3.
Repacked various primary plant valves including:
the bleed line motor operated sample valve (SA-MOV-513),
the pressurizer drain and capillary vent valved snd various angle stem valves.
h.
Cleaned the tubes of the main condens6r.
Lubricated the three boiler feed, three condensate, two heater drain and two circulating water pumps.
6.
Inspect ed and lubricated the vital bus inverter.
.h.
g 7
Plugged $ leaking tubes in No. 2 feedwater heater.
8.
Replaced manway gaskets on the right moisture separator.
Items performed during operation include:
1.
Inspected the No. 2 instrument air compressor and installed new valves installed new heater elements in the air dryer and cleaned the after. filter.
2.
Repaired some bolt heaters used in tensioning the studs in the main coolant check valve.
3 Inspected the group h pressurizer heater air circuit breaker.
r, h.
Made dimensional checks of the fuel handling system universal
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handling tool.
Inspected the fire protection system hose houses and hoses and replaced some hoses.
6.
A broken valve spring was replaced in No.
cl.trging pump.
7.
A leaking flange on No. 3 boiler feed pump discharge was tightened and reinsulated.
On April h the main coolant system was borated to lh93 ppm for the cold shutdown. After plant shutdown the system crud level increased from 0.32 ppm to 2.5 ppm. The oxygen concentration increased from less than 50 ppb to 380 ppb during the shutdown. After plant heatup the oxygen levels i
were reduced belcw the level of detection and remained below detection throughout the remainder of the period. During plant heatup, the coolant crud concentration, as measured from a bleed line sample, increased to H2 ppm the value decreased to 0.23 ppm af ter plant heatup.
After return to power, the main coolant boren concentration was reduced to 380 ppm.
The pressurizer capillary vent system flow rates were measured at 5h lbs/hr and hh lbs/hr for the right and left vents, respectively. These measurements were made April ll, follcwing this, the vents were closed to measure any gas buildup with time in the steam phase of the pressurizer.
Analyses of two separate main coolant gas samples, taken early and late in the period was as follows:
A-bl 6.3 x 10-1 pc/cc gas 6.6 x 10-1pc/cc gas Xe 135 1.5 x 10-2 pc/cc gas 1.7 x 10" pc/cc gas Xe 133 1.8 x 10-3 pe/cc gas 6.2 x 10-3 pc/cc gas Analyses of samples of the main coolant for tritium concentration have varied from 1.15 pc/ml to 1.5 pc/ml.
T
. Maa coolant iodine -131 specific activity was 1.3 x 10-5 pc/ml 4
and the I-131/.T-133 atomic ratio was 0.69.
Following the control rod exercise, the I-131 specific activity was 1.91 x 10-> pc/ml and ths I-131/
I-133 atomic ratio was 0.63.
This data indicates that core V is continuing to operate with no detectable fuel defects with the burnup on the fuel in the inner region almost 20,000 WD/MPU.
Xe-133 was 1.5$ x 10-Ss surge drum was sampled and the specific activity of The waste g pc/ml. The sample had the following gas concentrations:
02 - 0 05%
N2 - h7.2%
H2 - balance Reactor Plant Performance One 3 wire flux wire run was made under the following conditions with the follcwing results:
5% NT 527 F Tavg 375 ppm boron rod groups BDC @ 881/8" group A @ 89 2/8 Fq 2.h Fah = 2.0 Min q" DNBR = 3.3 Max. fuel outlet temp = 59150F t' L Q)
Control rod absorber section A75, a hafnium section removed at the last refueling, was examined in an attempt to determine the feasability of its reuse. The section was examined in the spent fuel pit where it is stored. It was inverted, placed in the fuel elevator, and raised to within a few feet of the surface of the water to examine the surfaces which mate with the control rod follower. Small amounts of wear were noted and attempts at wear measurement will be made before a final decision is rendered.
Turbine Plant Performance As a result of terminal difference data obtained on the feedwater heaters, #2 feedwater heater was opened during the shutdown. Five tubes were found leaking and were plugged.
Measurements of feedwater heater terr.inal difference since the
- 2 heater tube plugging are as follows:
~
- 1 6.0 q
j
- 2 15 0
- 3 11.2
. Taking advantage of the plant shutdown, the condenser tubes were cleaned, although it was not imperitive to do so at this time.
Data taken since the tube cleaning indicate a 5 F decrease in the terminal temperature difference of the main condenser.
Instrumentation and Control The following is a list of the major items performed during the month of April, 1.
Repaired and recalibrated #2 and #h main coolant pump bearing thermocouple and inspected those in #1 and #3 pumps.
2.
Replaced the two, valve position-turbine speed, pressure switches.
3 Recalibrated nuclear instrumentation channels 1, 2, 3, and h.
'~
h.
Replaced the detectors for channels 5 and 6 in thimble 7.
5 Replaced the spare BF detector in thimble 6 with a new 3
detector.
6.
Installed two thermocouples on the outer moat ring of the neutron shield tank (one on inner edge, one on outer edge).
7.
Dead-weight tested the pressurizer safety valve.
8.
Relecated the vapor container upper hemisphere temperature detector to a position directly above the missile shield.
9.
Recalibrated the main coolant temperature, stop valve inter-lock, bistables on the wide range temperature channels.
J 10.
Recalibrated the charging pump discharge pressure transmitter and indicators, 11.
Checked the operation of the pneumatic, pressurizer pressure system.
- 12. Recalibrated the main coolant system narrow range temperature Channels.
- 13. Recalibrated the pressurizer temperature system.
Ih. Readjusted the loop seal level alarms in the waste gas system.
Health and Safety During the month of April, two shipments consisting of a total of 109 drums of radioactive waste were made. The total calculated activity of these shipments was 11h6 millicuries.
. 4 Two spent fuel shipments, numbers 5 and 6 in the series, were made to the reprccessing faci]ity during April. Both shipments consisted of 10 spent fuel assemblies. The total calculated activity of shipment #5 was 0.89 megacuries and of shipment #6, 0.62 megacuries. The external readings for both shipments were similar and were as follows: Ganna radiation levels on contact with the loaded cask were 3.5 mr/hr rmH = m with 0.8-1.0 mr/hr generally. Gamma levels at one meter were less than 0.1 mr/hr. No neutron radiation or alpha contaminatio was detectabla. Contamination levels on E
the cask were less than 1 x 10- curies /100 cm, beta-gamna.
Liquid waste disposal releases totaling 100,276 gallons containing a gross beta-gamma activity of 93 jic and 287.78 curies of tritium, were dis-charged during the month of April. Gaseous waste released contained a total gross beta-gamma activity of ihh me and an additional h.$h curies of tritium.
All of the tritium in the gaseous release was due to a vapor container purge with all the discharge via the primary vent stack.
In addition to the above liquid releases, 236,970 gallons of water containing 1.36 curies of tritium, were discharged from the secondary plant.
The gross beta-gamma activity of this water was less the 10)1c.
A radiation survey was made in the vapor container shortly after shutdown. A similar survey was made last August after the shutdown for the core IV-V refueling. The major difference between the shutdowns is the fact that prior to the August shutdown, the plant was operating with ammonia in 4
the main ecolant to centrol pH.
The following readings are given for comparison:
Pressurizer Cubical April 5, 1966 August 11. 1965 fall contact)
General area 5-10 nr/hr 300-h00 mr/hr Spray line 8-18 r/hr 2-5 r/hr f~)
(
Heater bundles30-150 mr/hr 100-700 mr/nr Level dp cell 13-15 mr/hr 10 r/hr Main Coolant #2 Loop (contact)
April 5, 1966 August 11, 1965 General area 15-80 mr/hr 65-150 mr/hr Base steam generator 125 220 By-pass valve 85 200 By-pass piping 180 h70 Hot leg piping 2h0 150 Hot leg valve 80 150 Chem. injection valve 200 620 Cold leg piping 150 180 Cold leg valve h0 310 Personnel exposure for Yankee plant personnel as measured by film badge for the month of April 1966 were:
Average for all station personnel 131 mrem Maximum individual exposure 6h0 mren Attached is a summary of plant operating statistics and a plot of Daily Average Icad for the month of April 1966.
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YANKEE ATOMIC ELECTRIC COMPANY -- OPHtATING
SUMMARY
APRIL 1966 ELETRICAL MONTH YEAR TO DATE Gross Generation Wii llh,952,1CO
$1h,082,700 5,50h,923,600 Sta. Service (Wnile Gen. Incl. Iosses)
KWI 6,838,735 30,h83,605 376,8 %,099 Net Geraration KWH 108,113,365 h83,599,095 5,128,027,501 Station Service 5.95 5.93 6.85 Sta. Service (While Not Gen. Incl. losses)
WH 1 %,159 216,250 22,h57,828 Ave. Gen. For Month (719 Hrs)
KW 159,878 Ave. Gen. Running (629.h7 Hrs)
W 182,617 PIANT PHIFORMANCE Net Plant Efficiency 29.15 29.21 28.51 Net Plant Heat Rate Btu /WH 11,708 11,683 11,970 Ibs. Steam / Net WH lh.02 13.96 Circulating Water Inlet Temp.
Ruimum F
h2 h2 Minimum F
33 32 Plant Operating Fac or 85.98 95.8h 70.00 m
Reactor Plant Availaaility 88.26 96.99 81.51 NUCLEAR MONTH CORE V TO DATE Times Critical 1
16 373 Hours Critical HRS 63h.60 h,016.10 39,977.06 Times Scrammed O
1 50 Equivalent Reactor Hours @ 600 Mit HRS 618.20 3,8hl.68 30,000.72 Average Burnup of Core MID/IEu
- Control Rod Position at Month Did Equilibrium at 598.5 MC
- RMION ENTH TOTAL BUPJIUP Group A Rods out-inches 86 5/8 Group B 88 1/8 A (INNHL) 7h2.35 19,965.18 Group C 88 1/8 B (MIDDLE) 839.11 ll,986.9h Group D 83 1/8 C (OUTHl) 6hl.08 3,989.92 ZIRCAIDY TET ASSEMBLIES 1,057 77 6,619.00 Boron 300 ppm Ammonia 0
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