ML19351E206

Operation Rept 67 for Jul 1966

ML19351E206
Person / Time
Site:	Yankee Rowe
Issue date:	08/19/1966
From:	YANKEE ATOMIC ELECTRIC CO.
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ML19351E207	List: ML19351E206
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NUDOCS 8011260215
Download: ML19351E206 (10)

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YANKEE NUCLEAR FOJER STATION OPHIATION REPORT NO. 67 For the month of JULYlyj6 OV DOCKETED (m,

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-4 Submitted by YANKEE ATOMIC ELECTRIC COMPANY Boston Massachusetts August 19, 1966 8o11260 D 6

This report covers the operation cf the Yankee Atomic Electric Company plant at Howe, Massachusetts for the month of July 1966.

At the beginning of the period the plant was base loaded at 178 IWe, This power level was maintained tntil July 6 when the presence of s severe thunder and lightning storm in the local area made it advisable to reduce load.

The plant usually operates at a power level above $ho FWt, and at this power level the loss of one high voltage line will cause the loss of power supply to one nain coolant pury, _-sulting in a reactor scram due to low flow in that main coolant loop, When power level is reduced to

$h0 &lt. the loss of one main coolant pump will not result in a ecram; therefore, 3rocedures have been established which call for the reduction of power level to $h0 Hit under conditions of severe storm or disturbances on the electrical systen. These procedures were used to re3cce load on July 6.

Load was held at 162 FWe ($h0 Mit) overnight arJ returncd to 178 IWe on July 7 On July 10, tne plant tripped off the line without warning at 1809 nours.

Lightning had caused a 12ne fault on the Cabot Y-l?7 transmission line, f) and the circuit treakers at both ends of the line were tripped open.

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load at the time was 178 Mie, above the ene-loop low flow scram point, and therefore the reactor scrammed. The Cabot line was re-energized from the Cabot end within five minutes of the trip. Since the cause of the scram was readily determined, the reactor was broagnt critical and the generator was connected to the outside lines at 2150 hours0.0249 days <br />0.597 hours <br />0.00355 weeks <br />8.18075e-4 months <br />.

Load was increased to 160 }We and held at that level until 1220 hours0.0141 days <br />0.339 hours <br />0.00202 weeks <br />4.6421e-4 months <br /> on July 11 when it was increased to 178 FWe.

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During the remainder of the period the presence of lightning on the electrical system, storms in the local area, or weather bureau tornado warnings resulted in precautionary load reductions of from one to five hours duration on three occasions: July 12, July 19, and July 29 The plant was otherwise operated at maximum permissible levels until July 31, when a 50/ load reduction was made to allow cleaning of the condenser and the testing of some secondary plant equipment.

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completion of the condenser cleaning work.

On July 8, Core V reached the end of full pcwer operation with unadjusted pH, and on the lhth, the maan coolant system was ammoniated to take advantage of the reactivity increase due to high pH and the resulting extension of full power operation.

See the Reacter Plant Performance section of this report for details of the reactivity effects of the ammonta addition.

The shipment of spent fuel to the U.F.S. reprocessing -

ettinued through this reporting period. Nine elements were shipped in the,.. fuel shipping cask on July 12.

The empty cask was returned to the plant n July 27, and reshipped with nine elements on July 29, The two July shipments are the tenth and eleventh in the series nf spent fuel shipnents, bringing the number of elements shipped in the ten-element cask to 107 and the total of elements shipped to date to 123 On July 27, fourteen new fuel elements were received in tne second of three shipments from Westinghouse, The June 28 shipment of fourteen elements

-as visually inspected during the period; nc atnormal conditions were noted.

. S The bearing water temperature and cooling denand of No. 2 main coolant pump continued to increase sleuly throughcut the reporting period. The bearing water temperature was 1630F at the end of the period.

It had been anticipated that a stop-start operation of the pump would result in a step change in the rate of pump deterioration. The pump did trip after the scram on July 10, but the rate of deterioration did not step change; it continued at the same slow rate.

The vapor container air leakage rate was norral through the period.

PIMP SHUTDOUNS Shutdown No. 83-5-h 7 66 A 3.68 hour7.87037e-4 days <br />0.0189 hours <br />1.124339e-4 weeks <br />2.5874e-5 months <br /> shutdown resulting from a reactor scram.

Scram No. $1-5-2 7-10-66 An automatic reactor scram from a power level of $93 &lt. re-sulting from low flow in No.1 73 main coolant loop.

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PLANT MAINT'4.N_CE The following is a list of the major items performed by the plant staff during the month of July, 1966:

1. The air hoses and fittings on the spent fuel pit manipulator tool were replaced in an effort to reduce the incidence of air leaks.

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2. In April,1966, the universal handling tool was modified to allow an increase of 1/h inch in the travel of a control rod drive shaft button, bringing the total travel to 1 15/16 inches. Subsequent operational and dimensional checks have indicated that allowance must be made for the stretching of the pull rod in order to prevent the bottoming of the button. The 1/h inch of added travel has there-fore been reduced to 1/8 inch.

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3. The replacement of the carbon steel piping between the discharge of

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the water treatment acid punps and the acid mixing chamber has be n conpleted.

Polyvinyl chloride piping and fittings were used as replacement material.

h. Two multi-purpose heavy-duty cradles were f abricated. The cradles are capable of supporting the turbine high pressure spindle or the generator rotor during refueling maintenance periods.

5. The waste disposal power transformer, which has been unused since the removal of the evaporator electrodes, was moved to the railroad flatcar for storage prior to shipment to another power plant. The concrete base on which it was located has been removed, allowing more access space for vehicles between the primary auxiliary building and the waste disposal building.

INSTRUMSiTATION AND CONTROL The follcwing is a list of major items performed by the plant staff during the month of July, 1966:

1. The magnetic amplifier on the loop 1 main coolant hot leg temperature

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-3 channel was repaired.

The feedback capacitor had failed during O

the load reduction of July 6.

2. The loop 2 transmitter of the vap container audio monitoring system is intermittently inoperative. Due to the continued close surveillance of the main coolant pump in that loop, it was de-sirable to effect a repair; but the high radiation levels in the loop make access impossible. A spare tranJmitter in a directional container was therefore lowered into the loop and connected to the main control room receiver, providing a temporary expedient.

3. Recalibrated the spray controller on the low pressure surge tank.

The set point had shif ted slightly, causing an occasional unnecessary aut3matic start of the low pressure surge tank make-up pumps.

RFACTOR PLANT PERFORMARCE The full power oje. 4 tion of Core V with unadjusted pH ended at 1315 houra on July 8, 1966.

0. July lh ammonia was added to the main coolant system to extend the full powcc operation of Core V by using the reactivity gain that accompanies operation at high pH.

Following the addition of the ammonia the maximum rate of reactivity gain was approximately 0.8 x 10-h 45 K/K per hour, and the net reactivity gain was 0.2%.asK/K.

For the remainder of the period the depletion rate of fuel burnup was compensated for by the slow rate of reactivity gain due to the ammonia addition; the net result being a reactivity flatspot. At the end of the reporting period the burnup-corrected equivalent reactivity gain from the ammonia addition was approximately 0.5% d>K/K.

The following paraneters were determined by means of in-core instrumentation at 598 Mit, $26.8 F Tavg, O ppm boron, control rod groups B, C, and D @ 89 2/8, group A @ 72 6/8, and approximately 12 ppm ammonia:

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FAH - 2.0 Inn. DNBR - 3.3 Maximum outlet temperature - 591oF SECONDARY PIMT PERFOR!1mCE On July 31 the plant load was reduced to allow the cleaning of the condenser.

During the period of reduced load, the dl and #2 feedwater heaters were pressure tested for evidence of tube leakage which could be contributing to a rise in level in the heater drain receiver tank. It was discovered that neither of the feedwater heaters was leaking. The heater drain pumps were then tested and it was determined that the #1 heater drain pump was operating at less than $0% of its design capacity. The reason for the reduced pump capability is not known, but will be investigated at the earliest opportunity.

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-h-Feedwater heater terminal differences Q 177 We, 2.8 Hg backpressure,

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1. 2 - 15 5 F

1. 3 - 7.30F CHEMISTRY Main coolant dissolved oxygen levels were below the detection limit

(-5 ppb) throughout the period.

The average system crud level prior to the reactor scram on July 10 was 0.13 ppm. Following the scram the crud level The iodine-131 concentration increased from 3.8 x 10 b increased to 12 pp1s uc/ml to 9.7 x 10 uc/ml af ter the return to power.

At the end of the report pt.ried the iodine-131 concentration had decreased to an average value of h x 1G-h ne/ml and the I-131/I-133 atomic ratio was 2 7 The coolant tritium concentration varied between 13h uc/ml and 2.10 uc/ml, reflecting several plant load reductions and a reactor scram. A cal-

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culation of the primary to secondary leak rate in the #3 steam generator indicated leakage of 7.8 gallens per day.

Since this value is determined from main coclant tritium data, there could be some error due to the erratic tritium values.

Previcus leak rate values have been in the h -' 6 gallon per day range.

The main coolant was ammoniated on July 1h; and ammonia concentration was maintained between 9 and 15 ppm for the remainder of the period. System purifiotion was continued through the #2 mixed bed demineralizer and #h fflter;

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the cation cycle of the resin was ammoniated and the demineralizer is now in the NHk+, OH form. The average system cmd level with ammoniated coolant operation was 0.61 ppm. This is consistent with previous operation with this water chemistry.

A comparison of radicchemical analysis for crud samples before and af ter ammoniation is as follows: dpm/mg crud.

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I 7/11/66 7/20/66 7/11/66 7/20/66 Mn-5h 2.5 x 106 2 5 x 106 Fe - 59 2 9 x 106 3 1 x 106 cr-51 3 2 x 106 L.0 x 106 00-58 1.6 x 107 2.0 x 107 Ef -181 7,7 x 10h 7,3 x 10h Co-60 5 3 x 106

6. 9 x 106 A main coolant gas analysis on July 19 was as follows: uc/cc gas Xe - 133 9,5 x 10-2 Xe - 135 3.9 x 10-2 A - hl 3.2 x 10~-

HFALTH AND SAFEIT Two shipments of spent fuel were made during the period; the first with nine assemblics and 5 59 megacuries, and the second with nine assemblies and 5.33 megacuries. Gamma radiation levels from the cask for both shipments,

e on contact and at one reter, were gererally - 1 mr,hr and 4.1 mr/hr, respectively, with maximum of h and 15 mr/hr on contact and 0.h and 2 mr/hr at one noter, respectively. Neutron radiation levels from the cask at 1 meter were essentially the same for both shipments, showing 0.3 - 0 5 mrad /hr fastand40.00$ mrad /hr slow. Non-fixed surface contamination 2

levels wereel x 10-8 curies /100 cm teta-gamma with no detectable alpha ac tivi ty.

One shipment of radioactive waste was made during the period utilizing the control rod - follcwer cask. Included in the shipment were 2h control rod followers from Core I, and miscellaneous items retrieved from the reactor vessel during the last refueling. The estimated total activity of the shipment was 62 curies. Radiation levels from the cask on contact and at one meter showed maximums of 3 mr/hr and 0.3 mr/hr, respectively. Non-fixed surface contaminaticn levels as shown by repre-sentative 100 08 smears were /0el m-/hr beta-gamma with no detectable alpha actsvity.

During July the waste disposal liquid releases totaled $6,900 gallons contairang 0.07 me of gross beta-gamma activity and 16 curies of tritium. Gasecus waste releases during the came period totaled 10$ mc of gross beta-gamma activity.

In mddition to the above liqaid waste releases a total of 185,h00

,w gallons of water were discharged from the seccndary plant. The total gross beta-gamma and tritium activities released from the secondary plant were 410 uc and 1,3h curies, respectively, Radiation exposure doses for Yankee plant personnel, as measured by film badge for the month of July 1966 were:

Average accumulated expowure dose 215 mrem Maximum accum;3ated exposure dose 27 mrem D EIGN CHANGES

1. Installed a second float-operated switch on the primary buildiag sump tank, The contacts of the new switch will actuate the high level alarm in parallel with the existing high level alarm. thus providing a back-up against f ailure of the pumpout.

2. The pressure connection for the 1./c pressure alarm on control air pressure has been relocated from the compressor side of the filtars and driers to the output conrection to the plant air-operated instrumentation. With this modification, a valving error on the air dryer piping can be detected immediately. Under the former arrangement it was nece-ssary for air pressure to bleed from the system before the alarm pressure switch on the regulated instrument supply would detect the 1cw pressure ccndition.

, OPERATIONS The following Operating InstrucM on was revised and reissued during July:

50hD8 Shutdown of Individual Loops Cooldown of Individual Loops i

Attached is a summary of plant operating statistics and a plot of daily average load for the month of July, 1966.

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YANKEE ATOMIC EIJiCTRIC COMPANY DAILY AVERAGE IDAD for JULY 1966 200 -

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YANKEE ATOMIC EIETRIC COMPANY -- OPERATING SUM!%RY JULY 1966 KIETRICAL

}0 NTH YEAR TO DATE Gross Generation WH 128,055,800 903,590,700 5,89h,h31,600 Sta. Service (While Den. Incl. Losses)

WH 8,003,717 5h,517,839 h00,930,333 Net Generation WH 120,052,083 8h9,072,861 5,h93,501,267 Station Service 6.25 6.03 6.80 Sta. Service (While Not Gen. Incl. Losses)

WH 20,h80 236,730 22,h78,308 Ave. Gen. For Month (7hh hours)

W 172,118 Ave. Gen. Running (7h0.32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br />)

W 172,97h PIANT PEHFORMANCE Net Plant. Efficiency 27 71 28.66 28.h8 Net Plant Heat Rate Bru/WH 12,316 11,908 11,983 Flant Operating Factor 97.0h 97.06 71 41 Reactor Plant Availability 99.63 98.2h 82 32 i

NUCLEAR 10 NTH CORE V TOTAL Hours Critica1 HRS 7hl.27 6221.37 h2,182 33 Times Scrammed 1

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$1 Burnup Core Average MD/MPU 870.50 7258.13 Region Average ND/MPU A (INNER) 868.02 7085.65 22,627.h6 B (MIDDLE) 978.3h 8197 97 1h,957.07 C (OUTIR) 753.23 62h2.h3 6,2h2.h3 ZIRCAIDY TEST ASSENBLIES 1176.h9 10,129.91 10,129.91

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