ML19351E152
| ML19351E152 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 04/24/1963 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| References | |
| NUDOCS 8011250674 | |
| Download: ML19351E152 (10) | |
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YANKEE NUCLEAR IX)WER STATION 1 O OPERATION REPORT No. 27
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For the month of 1
MARCH 1963 l
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'ted by YANKEE ATOMIC ELECTRIC COMPANY Boston Massachusetts April 2h, 1963 l
O 8 o n e a o 6 '74
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J This report covers the operation of the Yankee Atomic Electric Company plant ct Rowe, Massachusetts for the month of March 1963.
Through March 17, the plant renained in continuous operation at a power level '
cf appro?.imately 170 K4 gross.
On March 15, hydruine was added to the MC system M ctserve the effects of high pH operation en overall reactor performance. Tha core reactivity behavior observed during the test was similar to that observed following boration of the MC at power in the recent boron shim control test.
A more detailed description of the hydrazine test can be found in the "SPECIAL TESTS" section of this report.
On March 18, during removal of ammonia from the )': system, the plant load gradually dropped off until on March 21 it was reduced to lt ? Kde. The inability ef the station to carry full power was a result of loss of r(activity during ammonia removal and an operating restriction limiting rod withdrawal to three inches per eight hours.
Concurrent with the rod withdrawal limitation, plant electrical output
( jwas reduced slightly commencing March 18, due to a partial loss of the circulating
water discharge siphon and accompanying increase in condenser back pressure. The partial loss of siphon occurred as a combination effect of low pond level and cut-over operations while installing a temporary vacuum pump on the circulating water system. Operation of the temporary vacuum pump was not successful in regaining the siphon.
,c On March 25, the plant was shut down to perform minor maintanance in both
_ the primary and secondary plants.
During the shutdown a freon test of the shield tank cavity liner was performed. When a gas pressure was established behind the lining, numerous pinhole leaks, particularly at veld areas, were detected and marked accordingly for repair during the forthcoming refueling outage.
Control rod drop time data were measured for all rods during the shutdown.
Minor modifications were made to the lower steam supf y connections to Nos.
1 and 2 feedwater heaters. Blank plates wem installed in place of orifice plates in an effort to improve heater performance. A more detailed description of the modifications can be found in the " DESIGN CHANGES" section of this report.
An outside consulting firm made measurements of main steam line vibration during turbine startup.
On March 26, while bringing the turbine up to speed for phasing, difficulty was encountered with the load limit control. Manipulation of the turbine load limit control over its range lowered load limi,t oil pressure normally. However,regardless of the relative settings of governor control and load limit, load limit oil pressure could not be raised above the governor oil pressure. It was first thought that a restriction in the oil supply to the load limit control caused the difficulty. The load limit control cup was removed, dimantled, and cleaned. However, after
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reassembly, the same difficulty was experienced. The main control oil supply system was then inspected and found clean. At this point a partial flush of the governing v
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oil system was made.
After flushing, the load lixit acted in a normal manner and the turbine was phased on the line. On March 28, at a load of 150 MWe gross, the load limit oil pressure again acted crratically, The difficulty could only be attributed to failure of the header check valve to seat properly. On the recommendation of the turbine manufacturer, an improved design check valve will be installed at the next scheduled shutdown.
For the remainder of the period, Icad was gradually increased until on March 31, full power operation was resumed.
During March, two Core I spent assemblies and one control rod were shipped for inspection and examination off site under an A.E.C. contract.
Nine new fuel assemblies were delivered to the plant during the month. New fuel assembly A 161, which had arrived at the site in March, was found to be defective
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) and was retum ed to the manufacturer. A total of kh new fuel assemblies are now in storage at the =M.te.
No reactor scrams occurred during March.
Plant shutdown g3 Shutdown No. 56-2-8 3/25-3/27/63 A 68.8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> scheduled shutdown for minor
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primary and secondary plant modifications and maintanance.
Maintenance Following is a summary of major activities carried out by plant maintenance personnel during March.
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1.
Repacked No. 3 charging pump U
2 An inspection of the generator and its auxiliary systems was conducted.
3.
Electrical inspection and adjustment of the 60 Ton work area crane was completed during the period.
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A new ion exchange tank was charged with resin and placed in service in the icn exchange pit.
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Repairs were made to a leaking steam inlet flange in the left hand noisture separator. Frequent take-up of the bolts is required to eliminate leakage at the flange. A new gasket design has been proposed by the manufacturer and will be installed tat the refueling outage.
6 The circulatirg water system temporary vacuum pump was installed.
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Pressure and deflection measuring devices used in the main steam line vibration analysis were installed.
8 No.1 pressurizer heater group air circuit breaker was renewed.
9.
Modifications were made to the steam supply piping at Nos.1 and 2 feedwater heaters.
10 Replaced the u.ncompensated ion chamber and two cable connectors in thimble 7 (channel 6).
Chemistry In line with the continuing investigation of the main coolant oxygen problem, as detailed in the February 1963, Operation Report, the pressurizer level was cycled on M1rch 1h, The resulting main coolant oxygen level increased from negative to 20 ppb, returning to negative after a 50 minute period.
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Except for this period, main coolant oxygan levels remained normal throughout the month.
On March 15, hydrazine was added to the main coolant system to observe the effects of high pH on overallreactor performance. NH3 concentration varied between h and 9 ppm. Cycling of the pressurizer level during the ammenia test
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did not increase the main coolant dissolved oxygen levels above normal. A descrip-(1 tion of the observed effects of the hydrazine addition to the main coolant system V
is included in the section "SPECIAL TESTS".
Prior to the shutdown of March 25; average main coolant specific activity ranged between 6.5 and 8.2 x 10-2 c/ml. After shutdown, and flushing the five inch main coolant loop bypass lines, the average main coolant specific activity rose to 3.O x 10-1 ge/ml.
A typical main coolunt crud analysis made during the period indicated:
6 Fe - 59 2.0 x 10 dpm/mg Ag - 110 m 1.1 x 103 Co - 60 8.5 x 105 Co - 58 2.5 x 106 Cr - 51 5.2 x 106 Mn - $h 6.7 x 105 The results of a main coolant gas analysis made after the return to power on March 27 indicated:
Ie - 135 2.h x 10-1 pc/ccgas Ie - 133 2.5 Kr - 85M 1.3 x 10-1 Throughout the period the Icdine-131 to 133 atomic ratio remained essentially unchanged at h.5.
Main coolant Iodine-131 concentration ranged between
- sj 1.5 x 10-3 and h.3 x 10-3 pc/ml.
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-h-Reactor P. snt Ferformance Core reactivity changes were followed closely before, during and immeaiately following the main coolant hydrazine test to permit evaluation of the change in water chemistry on core rea;stivity. A des:ription of the reactivity behavior is includeC in the section "SPECIAL TESTS *.
During the shutdown of March 25 - 26, control rod drop time measurements on all rods were made. The drop time from a 88 7/8 inch to a 6 inch position averaged 1.50 seconds during tha3e tests compared to 1.52 seconds at the start of Core II operation and 1.h8 seconds at the start of Core I operation.
Moderator temperature coefficient data measured during the shutdown indicated the following Plant conditions
(~ s Core II average burnup =
h383 MWD kJ MTU Core average temperature =
511 F Mreraturecoefficient
(- 2 30 ! 0.0h) x 10 AP/3F @ Peak Xenon Poisoning of 3 9% 21/0 f
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(- 2.90 1 0.12) x 10-h 4 F/'F @ Low Ienon Poisoning of 0.2% d /O Power coefficient data as ec aured during the loading to 150MWe on March 27, indicated the following Power coefficient
(-0.hh 2 0.07) x 10-h dt over the range of 0-h50 MWt
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MWt The fonowing were determined by means of in-core instrumentation measure-ments at a power level of 5h0 MW, control rod groups 6, 3,1, h and 5 at 88 7/8 inchesandgroup2fullyinsertek.
2.8 Fq
=
2.6 F
=
Minimum QDNB ratio = 2.8 Turbine Plant Performance Analysis of main steam line vibration continued during March. During the turbine sta-t up of March 27, an outside consulting service gathered data that is now being.tnalyzed in an effort to establish possible mechanisms for the observed y'.
vibrations in the system.
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In an effort to improve feedwater heater performance, in accordance with the manufacturer's recommendation, the lower steam s"nply to both Nos.1 and 2 heaters was blanked off. Prior to the moa.ification, xtraction steam had entered the vertical heaters at both the top and central regions. A slight improvement in performan:e was notea After tr.e change. A more detailed description of the heater performance study can be found in the section " DESIGN CHANGES".
A reduction in the circulating water siphon occured on March 18, while bringing the temporary air removal pump into service. This additional air removal pump was installed to determine whether entrapped air can be removad to restore the discharge ciphen. On March 18, the pond level was h.$ feet belt,a normal when the temporary vacuum pump piping wu connected into the existing vacuum priming system.
Low pond level had sufficiently increased air intake by the circulating water pumps to affect vacuum. With the normal air renoval system and the temporary pump in service vacuum i nproved slightly until the separation tanks filled with water nnd the pumps shut off. Intermittent operation of the two systems at low pond levels was insufficient to maintain discharge siphon. Re-c'esign of the separation tanks c.nd associated instrumentation to improve the efficiency of the air removal system is in Progress.
Plant calorimetric data and routine secondary plant performance data were acquired and analyzed during the month.
Heslth and Safety C
Liquid waste with a cetal activity of 0.20 millicuries was discharged V
from c.he plant during liaren. Waste gas containing an estimated 200 mi]11 curies was discharged during the r.eriod. At all timesthe concentration of waste products discharged from tne site was well below the maximum permissible.
Six drums of solid radioactive waste containing approximately 2h.3 n' t11 curies were prepared in March. None were shipped off-site.
During the period, decontamination of the control rod break joint mechanism base was accomplished using a sodium cyanide jell. Radiation levels of the piece before and af ter decontamination were 900 mr/hr and 60 mr/hr respectively.
v Surveys in the vapor container during the shutdown showed the follosing radiation levels:
Radiitunjevel Condition Area Personnel Hatch 0.7 mr/hr Cnarging Floor 1-3mr/hr st~e 01 Cavity 30 - j$ mr hr MC Icces Gen. Area 20-200 mr hr Byp'ss valves
$r/hr-15r/hr Contact-Before Flush a
Bypass valves 100-300mr/hr Contact-After Flush Chem. Inj. Valves 100-1500 nr/hr Contact Drain Valves 2r/hr-8r/hr Contact-Maximum h00 - 1000 mr/hr contact-Minimum m
s
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.. / Steam Generators 1 and h MC Inlet 150 - 1500 mr/hr Contact Shell Drain Inlet Area 300 - J00 mr/hr Contact Shell Drain Outlet Area 80 mr/hr Contact Tube Support Plate Area 80-150mr/nr Contact Temp. Test Area 60 - 100 mr Contact Top U-Tubes 13 - 15 mr Contact Shield Tank Cavity 50 - 200 mr/hr Gen. Area Floor to 9 ft. up walls 100- 500 mr/h-Gen. at 1 inch Northeast Corner 500 - 900 mr/hr
@ l inch Laydown Mech. Area 200- 300 m./hr General Instrumentation Work Area 200 - 300 mr/hr Moat Level One Core I control rod was shipped off-site for examination under A.E.C.
Radiation levels on the cask were 1 - 2 mr/hr. Contaimation levelg on the contract.
2 before decontamination and 500 - 1000 dmp/ft after cask were 1000 - 20,000 dpn/ft
('; decontamination.
Personnel exposure for Yankee plant personnel as measured by film badges for the month of February 1963 were Average for all station personnel =
$0 mr Maximum individual exposure =
280 mr
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In-Plant Training During the shutdowa of March 25 - 27, one member of the plant technical staff took the demonstrative portion of the A.E.C. operator 8s examination.
Design Changes During the Core I refueling outage external modifications were made to
(^') Nos.1 and 2 feedwater heaters. Based on the manufacturer's recomendation, an additional steam supply inlet to the upper section of both. heaters was installed.
The modifications were made by extending the existing steam supply line, which originally terminated at the central region of the heaters, and adding an inlet nozzle.at the top of each shell. An orifice plate to limit steam supply to the central region was also added. "'hese modifications were made to improve the thermal performance of the heaters and also to provide for increased heater capacity in anticipation of higher power operation.
Subsequent performance of the heaters during Core II operation prompted the manufacturer to suggest a conplete blanking off of the steam inlet to the central region. Ddring the shutdown the orifice plates were removed and blank plates were installed.
Typical heater perfomance data measured before and after the most recent mortifications were as follows:
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Feedwater Heater Terminal Difference No. 1 No. 2 Before 10.6 F lh.6 F o
0 After 7.0 F 13.0 F Special Testg During March a test was conducted to determine the effects on core reactivity and rain coolant chemistry rcsulting fror. the addition of hydrazine to the main coolant while at power. Three previous hydrazine tests had been conducted, t,wo in March,1962 and one in December,1962.
Contrary to previous tests in which a gradual increase in core reactivity accompanied the ir. crease in NH3 concentration, this test showed no departure from 7x nomal conditions until four hours after the hydrazine was added. This period was C/ followed by an eight hour period of higher than normal burnup. Approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after the injection of hydrazine to the main coolant, a slow rate of reactivity gain ccmmenced and continued over several hours. The magnitude of the reactivity gain was 0.6%dA being nearly twice that observed in previous ter.,s
( N O.32 to 0.36% dg ). Following return to normal coolant chemistry, core reactivity gradually returned to pre-test condition. Tnere was no permanent core reactivity change as a result of the chenistry test.
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U Plant Operations Attached is a surmary of plant operation statistics for the month of March 1963, and a plot of daily average plant load for the same period.
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YANKEE AMMIC EIECTRIC COMPANY - OPERATING EUNMARY MARCH 1963 ELEC'IRICAL MONTH YEAR TO DATE Gross Generation KWH 111,959,h00 326,979,900 2,028,h51,900 Sta. Service (While Gen. Incl. Losses)
KWH 6,806,h51 20,53h,755 151,291,322 Net Generation KWH 105,152,9h9 306,hh5,1h5 1,877,160,578 Station Service 6.08 6.28 7.h6 Sta. Service (While Not Gen. Incl. Losses)
KWH h11,390 596,528 1h,565,366 Ave. Gen. For Month (7hh HRS.)
W 150,h83 Ave. Gen. Running (675.2 HRS.)
W 165,817 PLANT PERFCRMANCE Net Plant Efficiency 29 33 29.38 Net Plant Heat Rate Btu /KWH 11,636 11,616 Lbs. Steam /NetKWH 13.61 13.7h Circulating Water Inlet Temp.
Maximum F
37 O
ginionun F
32 Plant Operating Factor 89.25 89.h2 66.01 NUCLEAR MONTH CORE II TO DATE Times Critical 33 295 Hours Critical HRS 699.55 h599.89 178h7.32 Times Scr h O
3 33 Equivalent Reactor Hours @ $h0 MWt HRS
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12059.8 Average Burnup of Core KJD/mtU Control Rod Position at Month End Equilibrium at 5ho MWt, <1h0F Tavg.
Group 1 Rods out-inches 88 7/8 Group 2 52 7/8 Group 3 88 7/8 Group h 88 7/8 Group 5 88 7/8 Group 6 88 7/8
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