ML19351E215

Operation Rept 65 for May 1966

ML19351E215
Person / Time
Site:	Yankee Rowe
Issue date:	06/24/1966
From:	YANKEE ATOMIC ELECTRIC CO.
To:
Shared Package
ML19351E213	List: ML19351E212 ML19351E215
References
NUDOCS 8011260220
Download: ML19351E215 (10)

Text

{{#Wiki_filter:ylle CopI ~ wau w fG ')-f . n.g. - o o i i N /\\ (b fnv YANKEE NUCLEAR POWER STATION / li ~ bl OPHIATION REPORT NO. 66 s :\\ 's :l2 7 JggghH ,0 m L%y' W For the month of ('A I jm)

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O D ~J O Submitted by YANKEE ATOMIC EIETRIC COMPAlff Boston Massachusetts June 2h, 1966 7.-, ~ ~, x~ h ,,( a n is xy;x ta tu arn b y 1 8011260 M O F_s 1805

.s This report covers the operation of the Yankee Atomic Electric Company plant at Rowe, Massachusetts, for the month of May, 1966. At the beginning of the period the plant w base loaded at 18$ We. During the period the seasonal increase in Snerman Poni water temperature occurred, gradually increasing the circulating water inlet temperatute from h2 F at the start of the period to 630F at the close of the reporting period. The increasing circulating water temperature caused a corresponding increase in condenser backpressure, resulting in a gradual decrease in plant load throughout the period to 173 We at the end of the period. Three short periods of cooler inlet water occurred when t.hs bydro-electric plant, located upstream of the Yankee plant, was operat vi for several hours on each of three Jays, sending cool water from the reservoir into Sherman Pond. The test program for the measurement of gas build-up in the pressurizer continued through the period. For details of this test program, ( j see the Chemistry section of this report. V On May 9, ten spent fuel assemblies were shipped to NFS for reprocesJing. The bearing water temperature and cooling demand (BTU /hr) of the No. 2 main coolant pump have slowly and steadily increased since the start-up from the april plant shutdown. At the start of Core V operation, No. 2 main coolant pump bearing water cemperature ran several drgrees higher than the o'.her three pumps. The normal bearing water temperature is controlled ( at approximately 1h0 F by adjasting the component cooling water flow to 0 N> the individual pumps; increr. sing the cooling water flow to No. 2 pump held tl.e bearing water temperature at approximately lh5 F. The te 7erature remained steady and the cooling demand, calculated from cooling water flow and comperature difference, also remained steady and comparable with the otWr pumps. In early April, however, the bearing water temperature and co ning demand for No. 2 main coolant pump started to increase very slowly, c-Q and, ef ter the April h-8 shutdown, continued to increase at a constant rate. By the middle of May the bearing yater temperature wss approximately 1$8 F and the cooling demand was $ x 10' BTU /hr above the normal demand of the other three pumps. Tl's increase continued slowly through the remainder of the reporting period. This condition is indicative of thermal barrier gasket leakage and the situation is being followed very closely. Several vapor container entries wer-cade during the period for pressurizer gas phase sampling and for rout:ne inspection; no adverse condi-tions were noted. On May 25 the monthly control rod exercise program was completed with no abnormal operation being noted. There were no plant shutdowns or reactor scrams during the month of May.

.~ s. Plant Maintenance The following is a list of the major items performed by the plant staff during the month of May, 1966: 1. Installed a drain line from the charging pumps to the grasity drain tank, providing a dircet path for draining cha ging prmp seal leakage. 2. The valves on No. 2 instrument air compressor were lapped and the discharge piping was cleaned to prevent rust and scale from entering the valves while the compressor is being placed in service. 3 Removed the sight glass and piping from the waste disposal ( ') evaporator to eliminate the high radiation due to crud trapped in the lines. The level transmitter detector was relocated to an internal standpipe in the evaporator. h. The anthracite was removed from the No. 2 filter in the water treatment plant. The internal surfaces of the filter tank were completely cleaned and repainted. The filter material will be renewed. (, 5. A paraffin inner liner was fabricated for the source vane shipping container. 6. In anticipation of possible main coolant pump repair work, the bolt henters were reconditioned and a decontamination pan was designed for use in the reduction of expected high radiation levels on the impeller. ( ) Instrumentation and Control The following is a list of major items performed by the plant staff during the month of May, 1966: 1. A defective amplifier tube was replaced in the log micro-ammeter on intermediate range channel h. The channel had failed during power operation. 2. New in-thimble coaxial cables were fabricated for the inter-mediate and power range ion chamber assembly removed from thimble 7 during the April shutdown. The detectors were checked and the assembly was reassembled for use as a spare unit. 3. A range selector switch was installed on the in-core thermo-couple recorder to eliminate the necessity of manually changing the range resistor cards when a range change is

required, b.

Recalibrated the waste disposal evaporator level transmitter aftr.r it was relocated to standpipe in the evaporator. Added a low level alarm switch on the level signal.

.s s e Performed the semiannual preventive maintenance and operational sheck of the two off-site accident-emergency air particulate monitoring systems. Reactor Plant Performance Core reactivity depletion during the reporting period was normal at approxima;ely 0.9% 6 K/K per 1000 FWtD/MTU. A plot of main coolant boron concentration versus burnup (FWtD/MIU) indicates, by extrapolation, that the end of Core V full power operation will be July 7,1966, providui no pH adjustment is made. If the pH is adjusted and the normal 0.7% 6 K/K reactivity gain is realized, full power operation will then be extended to August 1, 1966. As reported in Oparation Report No. 6h, an inspection of control rod absorber section A76 revealed small amounts of wear. The detailed c.() inspection was continued with the inspection of the mating follower section ~ Fhl and also the absorber and follower sections A63 and F3h, all of which were removed from the core during the Core IV-V refueling. The inspection was completed on May 11, 1966, and revealed latch-joint wear on all components. The control rod absorber V-groove locking areas were worn at the surfaces where contact was made with the follower locking springs; the locking spring' were also worn. Silicone impressions of the worn areas were taken. During the next refueling present core components will be inspected. r Redesigned control rod absorbers and followers are being procured in the event ( ) component replacement is deemed necessary. Westinghouse has reported the results of the Core V pH tests whi.h were conducted during February and March. (See Operation Reports Nos. 62 and 63). The experimental data clearly establishes that the pH reactivity gain is obtained from a change in pcwe. defect. The following conclusions (' were made: m 1. Reactivity associated with fue.' temperature (Doppler reactivity is the dominant cause of pH react?vity effect. 2. Fuel time constant and prompt power coefficient measurements show that an external mechanism, dependent on the pH of the coolant, significantly affects the pellet-to-coolant conduct-ance and pellet temperature. 3. Noise related to nucleate boiling increases with increase in pH. The following parameters were determined by means of in-core instrumentation at $98.8 FWt, $26.60F Tavg, 22h ppm Boron, control rod groups B, C, & D 0 88 h/8 and group A @ 86 5/8: Fq 2.2 = F6H 1.9 = 3.21 Min. DNBR = $90 F Maximum outlet temperature =

s -h-Secondary Plant Performance Secondary plant performance for the period is represented by the following datat Feedwater heater terminal difference

1. 1 8.30F
2. 2 lh.h F
3. 3 12.0 F Condenser cleanliness 66%

I ) Condenser terminal difference 320F Chemistry During the period the main coolant boron concentration decreased from 298 ppm to 156 ppm due to normal fuel burnup. Coolant crud level varied between 0.17 ppm and 0.39 ppm, except during the routine control rod exercise when the crud level increased to 1.8 ppm. The system oxygen concentration was maintained below the detection limit (less than 50 ppb). f^ The average main coolant tritium concentration was 2.3 pc/ml. i ) Measurements utilizing the tritium tracer iechnique indicate that the primary to secondary leak in the #3 steam generator has remained un-changed at h-6 gallens per day. A routine main coolant sample collected and analyzed on May 16 Q indicated a significant increase in both fission product iodine cur. centration m/ and isotopic atomic ratio. The data indicates that a fuel defect has developed. e iodine-131 concentration reached a new equilibrium level ofh0x10-{pc/mlonMay18andremainedessentiallyatthisvaluefor the remainder of the period. The I-131/I-133 atomic ratio increased from 0.69, the no defect value, to 2.3 The current iodine values are well below the ruinn iodine concentrations experienced in cores I, II and III where data also indicated that fuel defects existed. The pressurizer test program was continued and the vapor space and vessel drain system were sampled on May 3 after 2h days of no venting. Several samples of drain water indicated a dissolved oxygen concentration of from 1.7 to 3.2 ppm. This is the first time in the current test that significant quantities of dissolved oxygen have been found in the pressurizer water. The vapor space gas concentration was measured at 1665 cc of gas per kilogram of steam condensate; the concentration of oxygen in this gas sample vas normal 0.06%. However, it is interesting to note that the gas concentration was approximately 15% of the total gas fed to the vessel through the spray. If it is assumed that complete gas stripping occurs, and drain line samples indicate this to be true, then themis a considerable discrepency between observed and actual gas quantity in the pressurizer.

/ 4 The capillary vent system was opened and a vent flow of $6 1he/hr was established. After 8 days of venting the pressurizer v,apor space and drain line again were sampled. The drain line water dissolved oxygen concentration had decreased to a normal 70 ppb. Vapor space gas concentration also had decreased to 313 cc of gas per kilogram of steam condensate; however, gas oxygen concentration had increased to 0.h%. An attempt is now underway to substantiate these results by dupl?.cating this past test series. Testing of the new bleed line sample point continued during the reporting period. This sample point penetrates the bleed line upstream of the bleed line orifices and heat exchanger and utilizes the pressurizer sample line cooler and breakdown orifice. A comparison of crud samples from this location and from the normal bleed line sam}.le point indicate a discrepancy of from 50% to 80% with the upsteam sample () point yielding the higher results. In addition, radiochemical analysis of concurrent crud samples from the two locations have, on at least one occasion, indicated a difference in crud type. A crud sample from the normal bleed line sample point collected m May 13 had the following radiochemical analysis: dpm/ q, crud 6 6 Ma - $h 1.6 x 10 Fe - $9 1.9 x 106 Cr - $1 2.5 x 100 Co - $8 7.8 x 10 ( Hf - 181 5.2 x 103 Co - 60 2.6 x 106 Q,) A main coolant gas sample collected on May 16 had the following analysis: pc/cc gas 1 A - bl 6.3 x 10 2 ( ' Xe - 133 1.2 x 10-Xe - 13$ $ 6 x 10-2 Health and Safety No shipments of radioactive wasle were made during the month of May. One shipment of upent f tel, containing ten assemblies, was made to the reprocessirg facility during the month of May. The tott.1 activity of the shipment was calculated to be 0.71 megacuries. Gamma radiation levels from the cask on contact and at one meter were < l.0 and < 0.1 mr/hr above background. No neutron radiation was detected. Contamination levels 2 were < 1 x 10-8 curies /100 cm, beta-gamma, with no detectable alpha activity. During May, the waste disposal liquid releases totaled 101,600 gallons containing 1.52 me of gross beta-gamma activity and 28h curies of tritium. Gaseous waste releases during the same period totaled 339 me of gross beta-gamma activity. In addition to the above liquid waste releases, a total of 213,900 W gallons of water were discharged from the secondary plant. The total gross beta-gamma and tritium activities released from the secondary plant were < 10 pc and 1.71 curies, rsspectively.

s Personnel exposure for Yankee plant personnel ac menc" ed by film badge for the month of May 1966 were: Average for all station personnel 73 mrem lhr4== individual exposure 258 mrem Operations The following Emergency Instruction was revised and reissued during May: EI 505 B11 Large or Partial Ioss of Main Coolant. Attached is a summary of plant operating statistics and a plot of O Daily Average L ad for the month of May,1%6. 3~) O

] -o t, v YANKEE ATOMIC ELTTRIC COMPANY -- OPERATING

SUMMARY

MAY 1966 EIETRICAL MONTH YEAR TO DATE Groso ai.:.. ation WH 133,686,800 6h7,769,500 5,638,610,h00 Sta. Servica (While Gen. Incl. Loasse) WH 8,Eq,821 38,62h,h26 385,036,920 Net Generation NH 125,5h5,979 609,1h5,07h 5,253,573,h80 Station Se: v$e a 6.09 5.96 6.83 Sta. Service (While Not Gen. Incl. Ic:,ses) WH 0 216,250 22,h57,828 Ave. Gen. For Month (7hh Hrs) W 179,687 Ave. Gen. Running (7hh Hrs) W 179,687 PIA!Tr PERFORMANCE Not Plant Efficiency 28.27 29.01 28.51 Nat Plant Heat Rate btu /WH 12,072 11,76h 11,970 '/lant Operating Factor 99.h7 96.58 70.51 Reactor Plant Availability 100.00 97.61 81.79 NUCLEAR M0!TrH CORE V TOTAL Hours Critical HRS 7hh h760.10 h0,721.06 Times Scrammed 0 1 50 Burnup Core Average ND/MTU 892.28 552h.00 Region Averaga MD/MPU A (INNER) 910.h9 5333.86 20,875 67 B (tEDDLE) 102.67 62h2 51 13,001.61 C (0 UTER) 761.21 h751.13 h,751.13 ZIRCAIDY TEST ASSEMBLIES 115h.81 7773.81 7,773.81

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