ML19351E203

Operation Rept 68 for Aug 1966

ML19351E203
Person / Time
Site:	Yankee Rowe
Issue date:	09/20/1966
From:	YANKEE ATOMIC ELECTRIC CO.
To:
Shared Package
ML19351E204	List: ML19351E203 ML19354C382
References
NUDOCS 8011260151
Download: ML19351E203 (10)

Text

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-.c file Ccpy (f0Rt1AL) e YANKEE NUCLEAR PWER STATION OPIRATION REPORT NO. 68 For the month of g,

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This report covers the operation of the Yankee Atomic Electric Company plant at Rowe, Massachusetts, for the month of August, 1966.

At the start of the period, plant load was being increased after a one day load reduction for the cleaning of the condenser. Load was held at 160 Mie for most of August 1 while waiting for xenon equilibrium, and at 2005 hours0.0232 days <br />0.557 hours <br />0.00332 weeks <br />7.629025e-4 months <br /> was increased to 178 Mie.

On July 31 Core V had reached the end of full power operation and the beginning of the period therefore initiated the core " stretch-out" or core life extension program. As main coolant temperature and reactor power level decreased with fuel burnup, plant load correspondingly decreased throughout the period with minor daily variations due to changes in the condenser circulating water inlet temperature.

On August 11 and 23 two-hour load reductions were made because of the presence of severe lightning storms on the electrical system. When reactor power level is above 5h0 Mdt the loss of ona outside line will cause a reactor scram due to loss of power to one main coolant pump; reducing power below this level therefore lowers the probability of a plant scram due to a passing storm.

On the 25th the plant experienced a reduction in boiler feed capacity and the resulting low water level in the four steam generators caused a turbine trip and reactor scram. The No. 3 boiler feed pump had been placed in service for operational checkout after repacking. When No. 2 punp was subsequently removed from service, the levels in the steam generators started to fall, and the attempt to restart No. 2 pump resulted in the pump motor tripping on overcurrent. The steam generator levels

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continued to fall until the low level turbine trip set point was reached, causing turbine trip and reactor scram at 08h3 hours.

The cause of the decreasing steam generator levels was the failure of the check valve on the discharge of the No. 2 boiler feed pump to close when the pump was tripped, resulting in recirculation of feedwater from the boiler feed pump discharge header through the No. 2 pump. The reactor was returned to criticality and the generator was connected to the outside lines at 1107 hours0.0128 days <br />0.308 hours <br />0.00183 weeks <br />4.212135e-4 months <br />. Load was held at 15 Mie because of a problem with the indication of level in No. 3 steam generator, and subsequently, due to severe water hammer in the feed-water lines, main coolant loop No. 3 was shut down and the steam line non-return valve was closed.

Power level was then increased to the maximum level for three-loop operation. At 1635 hours0.0189 days <br />0.454 hours <br />0.0027 weeks <br />6.221175e-4 months <br />, loop 3 was returned to service and load was increased to 160 We.

On August 27 plant gross generation to date passed six billion kilowatt-hours.

One shipment of spent fuel was made during August. The empty spent fuel shipping cask arrived at the site on the l$th and was loaded that even-ing with eight spent h.1% assemblies from Core IV and one spent 3.h/ assembly from Core III. The shipment, which is the twelfth in the series of spent fuel shipments, lef t the site for reprocessing on August 17

. On August 2h the third and final shipment of new fuel elements llll for Core VI was received. The eight elements were uncrated on the 30th and, with the lh elements of the July 27 shipment, were being visually inspected at the end of the reporting period.

The control rods were exercised on August 18 and rod position lamp voltage readings were taken during the exercise.

No abnormalities were noted in the operation of the rods. The voltage measurements indicated that rods 17 and 22 were out of step with the remair' rods in group D; corrective action was taken.

The bearing water temperature and cooling demand of No. 2 main coolant pump have stopped the steady increase which has been carefully watched through the past few months of operation.

During the last three weeks of August there was no significant change in these parameters, in spite of the stop - start operation during the plant shutdown on the 25th.

J The vapor container air leakage rate was normal through the period.

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Plant Shutdowns Shutdown No. 8h-$-$ 8-25-66 A 2.h0 hour shutdown resulting from a reactor scram.

Scram No. $2-$-3 8-2 $-66 An automatic reactor scram from a power level of $h0 FWt, resulting

, ~~ 3 from a turbine trip after simultaneous

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low level in four steam generators.

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Plant Maintenance The following is a list of the major items performed by the plant staff during the month of August,1966:

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l. A lif ting fixture was designed and fabricated to facilitate the handling of the unitized control rod-follower assemblies during their installation in Core VI.

2. Both heater drain pumps were removed from service for inspection and repair.

No. 1 pump had gross erosion on the upper flange of the final stage Lmpeller housing, and minor erosion on two other housing flanges.

No. 2 pump was in a similar condition, but the erosion condition was less severe. Each pump was completely dismantled and reconditioned, and the pump motors and motor leads were electrically checked.

3. Af ter No. 2 boiler feed pump motor tripped by overcurrent protective relaying on August 25, the moto was dismantled for inspection and found to be in good condition.

The motor was cleaned and the rotor was painted.

h. The check valve on the discharge of N3 2 boiler feed pump was dismantled for determination of the cause of its failure on August 25 The disc hinge assembly had worn sufficiently that the disc could become lodged in the open position. An inspection of No. 3 boiler feed pump discharge check valve revealed a less-severe similar condition; both valve disc hinges were rebushed.

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. 5. The hooks, drums, gearing, and brakes on the yard area crane were inspected.

6. In the water treatment plant, the resins of No.1 demineralizer were replaced, and the rejuvenation of No. 1 filter was completed.

Instrumentation and Control The following is a list of major items performed by the plant staff during the month of August,1966:

1. A newly-acquired vibration transducer was tested and adapted for use with the Visicorder. Reference traces were taken at various points on most of the rotating equipment in the secondary plant.

2. The semi-annual preventive maintenance and calibration checks were per-formed on the plant Civil Defense equipment and the two off-site air (m

particulate monitoring stations.

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3. The narrow range cold leg main coolant temperature channels were re-calibrated to a lower range, thus keeping the temperature indication on-scale as main ecolant temperature decreases with core stretch-out.

h. Replaced the slidewire on the No. 3 wide range steam generator level recorder-retransmitter; the channel nad failed to follow the level decrease during the reduction in feedwater capacity on August 25

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Reactor Plant Performaned On July 31, Core V reached the end of full power operation. The rate of power decrease during the start of the core life extension was normal, following a coastdown rate which was predictable from the experience of previous core stretch-out periods. After the reactor scram on August 25, however, the

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reactor power has been approximately h Mit higher than predicted. It is 1

assumed that the reactor scram and resulting transient on the ammoniated main coolant system has resulted in a small reactivity gain, possibly due to crud redistribution. The addition of ammonia on July lh had resulted in a burnup-corrected equivalent reactivity gain of approximately 0.5%dK/K, which was 0.2$%4 K/K less than expected. The h Nt $acrease experienced af ter the August 26 scram may be a part of the 0.2546 K/K unrealized gain.

The following paramaters were determined by means of in-core instrumen-tation at $68 N t, $17.50 F Tavg, O ppm boron, control rod groups B,C, and D @

89 $/8, group A O 90:

FQ 2.36 F6 H 1.96 Min. DN3R 3,60 Maximum outlet temperature

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-h-Secondary Plant Performance G

On July 31, while plant load was reduced to allow condenser cleaning, it was discovered that No. 1 heater drain pump was operating at less than 50%

of its design capacity.

(Operation Report No. 67, July 1966) On August 8 the pump was removed from its well for inspection. The reason for the reduced out-put was the erosion of three impeller housing flanges, allowing water to escape from the pump internals and recirculate to the pump suction. The repair of the pump resulted in a 15 psi increase in pump discharge pressure. Subsequent inspection of No. 2 heater drain pump revealed a similar, although less severe, condition.

The cleaning of the condenser resulted in a gain of 5.5 W e in plant output (corrected to pre-cleaning conditions) and a decrease of lo F in con-o denser terminal difference. As a follow-up to the condenser cleaning, a program has been initiated to reduce condenser tube fouling by the periodic

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addition of chemicals to the condenser circulating water.

The effectiveness of the program will be evaluated by condenser inepaction during the refueling v

shutdown.

Feedwater heater terminal differences @ 172 We, 2.8" Hg backpressure,

$230F:

1. 1 - 6.8cF

1. 2 1h.8oF

1. 3

- 11.3oF

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Chemistry Operation with ammoniated main ecolant was continued throughout the period.

Primary water dissolved oxygen levels were below the detection limit

(< $ ppb). The average system crud level was 0.h7 ppm, not including increases to lh 8 ppm and 2.2 ppm that followed the August 18 rod exercise and August 25 reactor scram.

The coolant average iodine-131 specific activity was 2.1 x 10-h ux/ml and the I-131/I-133 atomic rn+io was 2.1; following the return to I]

power on the 25th, these values increa,ed to 7.h x 10-h uc/ml and 3.h, respectively.

Tritium balance calculations indicated an increase in the primary to secondary leak rate from h - 6 gallons per day to l$-18 gallons per day at the end of the period. An attempt was made to determine if the increased primary to secondary leak rate was due to increased leakage from No. 3 steam generator or from leakage on any of the other steam generators. A 0.5 ppm sodium concentration was established in the coolant by injecting a solution of sodium hydroxide into the charging pump suction. The coolant specific activity increased from 9.5 x 10-2 uc/ml to h.2 x 10-1 uc/nl in 2h hours as the sodium was activated (Na-23 n,y Na-2h). Analysis of secondary side steam generator waters indicated that the No. 1 steam generator has developed a leak. The data indicates that the leak rate in the No. 1 steam generator equals and is probably more than that of the No. 3 stean generator.

The following radiochemical analysis inc'ic ates the buildup of circu-lating crud specific activity W.V is consistent with ammo m ced coolant operation, dpm/mg crud.

8/5/66 8/17/66 8/5/66 8/17/66 Mn-$h h.h x 106 1.2 x 107 Fe-59 9.h x 106 6

3,g x 10 Cr-51 7.h x 106 2.0 x 107 Co-58 3.5 x 107 9.6 x 107 Hf-181 1.h x 106 5.9 x 106 Co-60 9.8 x 106 h.6 x 107 A main coolant gas analysis on August 22 was as follows: uc/cc gas.

Xe-133 1.2 x 10-1 Xe-135 h.0 x 10-2 A-kl h.7 x 10-2 Health and Safety

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One shipment of spent fuel was made during the period. The shipment contained nine asst.nblics with a calculated total activity of h.78 megacuries.

Gamma radiation levels were generally less than 1 mr/hr with a maximum of 20 nr/hr on centact, and generally less th.'n 0.1 mr/hr with a maximum of 2 5 mr/hr at one meter. Neutron radiation levels at one meter were approximately 0.9 mrad /hr fast and 0.008 mrad /hr slow. Non-fixed surface contamination levels were less than 1 x 10-10 curies /100 cm2 beta-gamma with no detectable alpha contamination.

The following radioactive warte shipments were made during August:

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Two concrete casks, each containing 12 guide tubes and 12 curies of activity.

Radiation levels from either of the casks were approximately h0 mr/hr maximum contact and $ mr/hr maximum at one meter. Non-fixed surface contamination was measured as less than 0.1 mr/hr per 100 cm2 beta-gamma, with no detectable alpha contamination.

f The Vandenburg cask containing b shir rods, 8 shim extensions, 5 neutron sources, 2 specimen baskets, and 1 drive shaf'. The total estimated activity of the shipment was h00 curies. Radiation.evels from the cask on contact wt re generally 10-2$ mr/hr with a maximum of $0 mr/ nr, all gamma. Gama levels at a distance of six feet were generally 1-5 mr/h; with a maximuu of 8 mr/hr. No neutron radiation was detectable external to the cask. Non-fixed surface contamination levels, as measured from 100 cm2 smears, were less than 0.1 mr/hr beta-gamma, with no detectable alpha.

Entry was made into # 3 loop (idle) during return to power on August 25 for inspection. Radiation levels in the loop were:

Top of spiral ladder 30 mr/hr Half-way down ladder 50 nr/hr Bottom of ladder (pump-side) 150 mr/hr By-pass stop valve (contact insulaticM

$00 mr/hr General area (bottom of ladder to top of sub-floor ladder; 150-600 mr/hr

. During August the waste disposal liquid releases totaled 98,600 gallons containing 1.25 me of gross beta-gamma activity and 13h curies of tritium. Gaseous waste releases during the same period totaled 99 me of gross beta-gama activity.

In addition to the above liquid waste releases a total of 153,350 gallons of water were discharged from the secondary plant. The total gross beta-gamma and tritium activities released from the secondary plant were less than 6 uc and 2 curies, respectively.

Radiation exposure doses for Yankee plant personnel, as measured by film badge, for the month of August,1966 were:

Average accumulated exposure dose 37 mren i

14aximum accumulated exposure dose 173 mrem Operations _

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

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YANKEE ATt EIETRIC COMPANY -- OPERATDJG

SUMMARY

AUGUST 1966

_EIETRICAL ENTH YEAR TO DATE Gross Generation WH 122,869,600 1,026,h60,300 6,017,301,200 Sta. Service (While Gen. Incl. Losses)

WH 7,636,171 62,15h,010 h08,566,50h Net Generation WH ll5,233,h29 96h,306,290 5,608,73h,6%

Station Service 6.21 6.06 6 79 Sts. Service (While Not Gen. Incl. Iosses)

NH 1h,537 251,267 22,h92,8h5 Ave. Gen. For Month (7hh hours)

W 165,lh7 Ave. Gen. Running (7hl.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />)

W 165,682 PIMT PERFORMANCE Net Plant. Efficiency 27.85 98 56 28.h6 Net Plant Heat Rate Bru/W H 12,25h 11,9h9 11,991 a

l'lant Operat:tng Factor 92.69 96.50 71.75 Reactor Plant Availability 99 79 98.hh 82.57 NUCLEAR ENTH CORE V TOTAL Hours Critical HRS 7h2.h7 6963.8h h2,92h.80 Times Scrammed 1

3 52 Burnup Core Average WD/IEU 831.h3 8089.56 Region Average WD/MrU A (INNER) 836.38 7922.03 23,h63.8h B (MIDDLE) 927 72 9125.69 15,88h.79 C (OUTER) 725.h0 6967.83 6,967.83 ZIRCAIDY TEST ASSEMBLIES lllh.30 11,2hh.21 ll,2hh.21

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