ML19351E201
| ML19351E201 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 10/21/1966 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML19351E200 | List: |
| References | |
| NUDOCS 8011260145 | |
| Download: ML19351E201 (11) | |
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t YANKEE NUCIEAR POWS STATION OPERATION REPORT NO. 69 For the month of SEPTDGE 1966
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Submitted by YANKEE ATOMIC ELECTRIC COMPANY Boston Massachusetts October 21, 1966 m
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Tnis report covers the operation of the Yankee Atcmic Electric l
Company plant at Rowe, Massachusetts, for the month of September, 1966.
At the beginning of the reporting period the plant was operating at a pcwer level of 160 MRe.
Plant load continued to decrease at a fairly uniform rate as operation continued in the Core V core life extension program. Fuel burnup rate was consistent with that of ammonisted " stretch-out" operations on the previous reactor cores, resulting in a load decrease rate of approximately 2/3 Mie per day. Circulating water inlet temperature was in the range of $h F to $60F throughout the period.
By September 19 plant load had decreased to 150 FWe. At that time the addition of samenia to the main coolant system was secured and ammonia removal was initiated by means of cation exchange. In 196$ the Core IV refueling shutdown had been made with ammonia in the main coolant system, and during the refueling period it was noted that the radiation levels in the low velocity areas of the main coolant system were three to five times higher than the levels noted in any of the previous refueling periods; all previous refueling shutdowns had been made from a low pH con-(~ ')
dition. The higher radiation levels in 1965 were apparently due to increased crud accumulation, resulting from the high pH shutdown chemistry. The removal of ammonia before the 1966 Core V refueling shutdown, which is scheduled for the first week in October, is expected to result in lower re-fueling radiation levels.
The effects of the ammonia removal were noted over the next two days as plant load decreased at a rate which was faster than the established coastdown rate. On September 22, load was lh2 M4e and the normal coastdown
('_l rate had been re-established. On the 28th the main coolant loop by-pass
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valves were opened in a further effort to reduce the radiation levels which will be encountered during the forthcoming refueling by allowing the release of the crud trapped in the by-pass lines. The opening of the valves resulteu in increased by-pass flow around the reactor core and a subsequent load decrease of approximately $ FWe. At the end of the period plant load was 133 Mde.
(,j Two shipments of spent fuel were made during the month of September.
Each shipment consisted of ten elements. The first shipment lef t the site on the 9th, and the empty cask was returned on September 26.
It was then loaded, and chipped with ten elements on the 28th.
The two September ship-ments are the thirteenth and fourteenth in a series of spent fuel shipments, bringing the number of elements shinped in the ten-element cask to 136 and the total of elements shipped to d.ce to lj2.
After the head was placed on the loaded spent fuel shipping cask on September 26, the spent fuel pit cooling pump was primed and started. The pump priming valve was inadvertently lef t open, resulting in the subsequent filling of the spent fuel pit with an overflow spill of about 33 gallons.
Most of the spilled water ran over the north floor of the pit, down the ex-terior wall, across a small section of asphalt paving, and into a storm sewer connected to the east side culvert system. A few gallens leaked into the new fuel vault.
A drain were flushed with service water, and the water on the floor of the new The spent fuel pit exterior wall, the asphalt paving and storm fuel vault was mopped and the area cleaned.
. 9 occurrence,he sample of spent fuel pit water, taKen immediately after the T indicated a gross activity of 3.2 x 10-3 ue/ml.
A sample taken four days previous to the occurrence indicated the gross activity to be
$.h x 10-> ue/ml with a tritium concentration of 5.h x 10-3 uc/ml. A con-tinuous service water and intermittent fire water flush of the east side culvert system was initiated and continued for a 2h hour period, Sufficient dilution water (75,000 gallons) was added to the culvert to reduce the gross and tritium activity to 1.h x 10-0 uc/ml and 2.h x 10 6 uc/ml, respectively, when averaged over 2h hours.
Samples of drainage water leaving the east side culvert were taken 2h and h2 hours after the occurrence and indicated gross cctivity levels, as measured by an outside laboratory, of 2.0 x 10-9 ue/ml, and by the plant laboratory as < $ x 10-9 ue/ml; the measured tritium value after 2h hours was 3.h x lo-> uc/ml.
The overflow spill from the spent fuel pit resulted in a total re-lease of h uc gross beta-gamma and 670 uc of tritium activi.ty.
O When plant personnel were obtaining samples of drainage water from the culvert system after the spent fuel pit overflow spill, the initial samples were taken from the wrong culvert In 1965 Sherman Dam was raised, and, because of the relocation of the road, it was necessary to divert the east culvert into Sherman Pond. The initial sample was taken from the point where the east and west culverts formerly met, and therefore the samples were actually taken from the west culvert. An average of two samples taken from the west side culvert indicated a gross activity of 6.7 x 10-7 uc/ml.
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During the investigation of the source of this activity, a relief valve on the safety injection tank heating system was found to be leaking slowly into a floor drain in the primary auxiliary building.
The floor drain is piped underground into the side of a deep storm sewer just outside the building, and the sewer drains to the west side culvert system. The relief valve leak had existed for less than one day, and a leak rate measurement indicated that less than eight gallons had leaked from the valves alysis
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of the safety injectio 1 water indicated a groes activity of 3 x 10' uc/ml V
and a tritium activity of 1.1 x 10 uc/ml The sample of the west side culvert water, collected 2h hours af ter the previous sample, was measured by an outside laboratory and indicated a gross activity of 1.2 x 10-0 uc/ml and a tritium activity of 01 x 10-5 uc/ml.
The total release resulting from this occurrence was 0.6 uc gross beta-gamma and 3.32 me of tritium activity.
It was necessary to rv the vital bus inverter from service on Septenber 16 due to the failui
'nboard bearing of the generator.
The bearing could not be replaced becam f excessive wear in the generator end bell. The vital bus was on backup supply at the end of the period.
In an effort to ninimize the cloudy water conditions which have occurred in the d.ield tank cavity during past refueling periods, continuous purification of the contents of the safety injection tank was started on September 19. The boric acid solution is pumped through a 1-3 micron filter A
and the tank contents are periodically recirculated to wash the tank walls.
The cleaning process will continue until use of the water is required.
_3 The lower lock valve in the vapor container fuel chute was 9
program; no leakage was found.
pressure tested as a part of the 1966 vapor container penetratior. testing The monthly control rod exercise was performed on September 28 and rod position lamp voltage readings were taken during the exercise. No abnormal rod operation was noted. Rod 18 was stepped out two steps because the voltage measurements indicated that it was out of step with the remain-ing rods in group D.
Representatives of the International Atomic Energy Agency (IAEA) made a scheduled inspection of operational records and an inventory of new and spent fuel assemblies. The last I.A.E. A. inspection was in June,1966.
The vapor container air leakage rate was normal through the period.
No plant shutdowns or reactor scrans occured during the month of m()
September.
PLANT MAINTE!ANCE The following is a list of the major items performed by the plant staff during the month of September, 1966:
- 1. Replaced the rubber fabric expansion joint at the suction of r,
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the No. 3 condensate pump. The expansion joint had partially
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collapsed, and since this type of failure has occurred in the past, the use of expansion joints with steel reinforcing rings is being investigated.
- 2. The check valve on the discharge piping of the No 1 boiler feed pump was dismantled and inspected. The dise hinge was worn enough to require rebushing, but the wear was not as (m) severe as that found on the discharge valves of No4 2 ard f
No. 3 boiler feed pumps which were inspected during the previous reporting period.
- 3. Seal discs were prepared for installation in the upper and lower manholes of the vapor container. The manholes were used during construction, and each has been sealed leak-tight with a gasketed blank flange since that time. The discs will bc seal welded into the manhole penetrations, thus eliminating them as a source of air leakage in the futu w
- h. No. 2 boiler feed pump was inspected and new shaft sleeves were installed. The face of the balancing sleeve had nine radial cracks about $/16 inch deep, possibly caused by contact with the balancing drum when the pump experienced reverse flew on August 2$3 1966.
$. New,uction and discharge valves were installed on Nc 2 waste gas conpressor.
- 6. No. 3 charging pump was repacked and two plungers were replaced.
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- 7. No. 2 purification pump was removed from service. The design of the purification pumps is now obsolete, making it difficult to obtain replacement parts. Replacement pumps are therefore being installed in place of the existing pumps to alleviate the maintenance problem.
- 8. The following list contains those major items of maintenance performed in preparation for the forthcoming refueling shutdown.
A. The reactor head stud storage shed was strengthened and the heating system was checked.
B. The Lerma periscope platform was cleaned and painted.
C. New finger operating buttons were installed in a spare control rod drive shaft.
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D. An air cooling manifold was fabricated for stud cooling during the proposed inspection of the main coolant loop check valves.
E. A test flange was fabricated for the testing of the four large steam safety valves.
F. New hoses and fittings were installed on the plate and
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j barrel handling fixture.
G. A disposable filter, wash pan, and pump were rigged for decontamination work on No. 2 main coolant pump preparatory to the proposed inspection and overhaul work.
INSTRUfETATION and C0!UROL g
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The follcwing is a list of major items performad by the plant staff during the month of September, 1966:
- 1. Recalibrated all pressure gages and transmitters in the turbine startup panel and the associated receiver gages on the main control board.
- 2. The main coolant hot leg temperature channels were recalibrated to a lower range in order to keep the indication on-scale as main coolant temperature decreases with power ccastdown.
- 3. The Heise gage was recalibrated for use in the safety valve tests during th; plant shutdown.
- h. A new portable underwater television system was received and successfully tested in the spent fuel pit.
- 5. Preventive maintenance was performed on the main control board receiver - indicators connected to primary auxiliary transmitters, s
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REACTOR PIANT PERFORMANCE The rate of reactor power coastdown as determined by measured cal-orimetric data continued as predicted from the data of previous "s tretch-out "
periods. The removal of ammonia on September 19 was accompanied by a decrease in reactor core output of approximately 22 IUt. After the ammonia removal, normal coastdown continued at the reduced power level until the main coolant loop by-pass valves were opened on the 28th. Reactor power then decreased by approximately 7 IWt.
The following parameters were determined by means of in-core instrumentation at h95 IMt, h96.90F T avg, 0 ppm boron, control rod group A, B, C, and D 0 90-3/81 Fq - 2.h5 F.3 H - 2. 0h
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Min. DNBR - h.3h Maximum outlet temperature - $$80F SECONDIRY PIANT PEFORMAIL' Feedwater heater terminal differences @ l$2 IMe, 2 1 "Hg back-pressure, 503.50F Tavg:
E' gl - 8.10F
- 2 - 9.50F
- 3 - 7,2 0F CHEMISTRY Primary water dissolved oxygen levels were below the detection limit
( <$ ppb) during the period. Operation with annoniated water was continued until September 19 At that time, purificaticn flow and the addition of g) ammonia to the main coolant system were secured.
Purification flow was re-established through No. 3 cation exchanger to initiate the removal of ammonia from the main coolant system.
The average coolant crud level was 0.21 ppm prior to the control rod exercise and the opening of the $" loop by-pass valvgs on the 28the The cool-ant average iodine - 131 concentration was 1.9 x 10' uc/ml and the I-131/I'-133 atomic ratio was 1.6 during ammonia operation. Without anion purification following ammonia renoval, the iodipe-131 concentration and tne I-131/I-133 atomic ratio increased to h.6 x 10-4 uc/ml and 3.02, respectively.
During the period the status of primary to secondary leakage in the steam generators was again investigated. The test procedure involved the use of the sodium tracer technique and was essentially a repetition of the previous program, although several improvements in procedure and sampling methods were incorporated into the latest test. The test confirned the presence of primary of S.G. No. 3/S.G. No. 1 of about h/1.
to secondary leakage in No. 1 and No. 3 steam generat. rs with a leakage ratio On this basis, the present leakage situation is approximately lh gpd and 3 gpd for steam generators #3 and #1, respectively.
d-A comparison of radiochemical analysis for crud samples during 4.
anmonia operation and af ter ammonia removal is as follows: dpm/mg crud.
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Ammoniated Unadjusted Ammoniated Unadjusted 9-2 66 9-23-66 9-2-66 9-23-66 Mn-$h 7.7 x 107 h.h x 106 pe-39 g,1 x 106 3.6 x 106 Cr-$1 2.2 x 107 8.2 x 106 Co-58 6.0 x 107 2.6 x 107 Hf-181 3.9 x 106 1.6 x 106 Co-60 2.1 x 107 9.8 x 106 A main coolant gas analysis on September 20th was as follows:
ue/cc gas Xe-133 5.1 x 10-2 2
Xe-135 h.3 x 10 2 A-bl 6.7 x 10-
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HEALTH and SAFETY No shipments of radioactive waste were made during the month of September, 1966.
Two shipments of spent fuel were made during the period with a total of 20 assemblies and 1.98 megacuries. On the first and second 3
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shipments the respective gamma radiation levels were 7 and h mr/hr maximum
'd contact, and 0.8 and 0.1 mr/hr maximun at one meter.
No neutron levels were detected from the first shipment; the second showed approximately 0.3 itrad/hr fast, with no detectable slow neutron dose rate.
Non-fixed beta gamma surface contamination for both shipments was generally less than 1 x 10-9 curies /100 cm2 with a maximum of 2 x 10-9 curies /100 cn. No d
alpha contanination was detected on either shipment.
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During September the waste disposal liquid releases totaled 66,700 gallons containing 0.3 me of gross beta-gamma activity and 91.53h curies of tritium. Gaseous waste releases during the same period totaled 9h.2 mc of gross beta-gamma activity.
In addition to the above liquid waste releases, a total of 135,300 gallons of water were discharged from the secondary plant. The total gross beta-gamma and tritium activities released from the secondary plant were <7 uc and 2 curies, respectively.
Radiation exposure doses for Yankee plant personnel, as measured by film badge, for the month of September,1966 were:
Average accumulated exposure dose 90 mrem Maximum accurulated exposure dcse 867 mrem
. 9 DESIGN CHANGE 3 1.
An ammeter was installed on the main control board to provide remote ind.. cation of the current being delivered by the emergency Diesel generator. This installation will allow the operator at the main control board to monitor the load carried by the generator at any time during the loss of AC power condition. With this change, it will no longer be necessary for an operator to go to the ammeter at the generator to de-termine the loading of the generator before equipment on the generator bus is energized from the main coolant board.
2.
A scintillation detector was installed on the south wall of the turbine hall above the crane rail, and the associated signal detection, read-out, and alarm equipment were installed c
in the radiation monitoring panel.
This installation is for (l
the detection of radiation emanating from the vapor container in event of a large break in the main coolant piping, and relieves the gate house guard from the duty of determining the radiation level, thus allowing the guard to perform other emergency duties.
OPERATIONS Attached is a summary of plant operating statistics and a plot of daily average load for the month of September, 1966.
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YANKEE ATOMIC ELECTRIC COMPANY -- OPERATING
SUMMARY
SEPTEGDt 1966 ELECTRICAL
)ONTH YELE TO D&TE Oross Generation NH 107,252,200 1,133,712,500 6,12h,553,h00 Sta. Service (While Gen. Incl. Losses)
WH 7,1ho,113 69,29h,123 h15,706,617 Net Generation WH 100,112,007 1,06h,h18,377 5,708,8h6,783 Station Service 6.66 6.11 6.79 Sta. Service (Whilm Not Gen. Incl. Iosses)
WH 0
251,267 22,h92,8h5 Ave. Gen. For Ibuth (720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br />)
W 1h8,961 Ave. Gen. Running (720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br />)
W 1h8,961 PIANT PERFORMLNCE Net Plant. Efficiency 27 39 28.h5 28.hh Not Plant Heat Rate btu /WH 12,h60 11,996 12,000 Plant Operating Factor 8h.62 95.20 71.95 Reactor Plant Availability 100.00 98.61 82.82 NUCLEAR
)ONTH CORE V TOTAL Hours Critical HRS 720 7,683.8h h3,6hh.80 Times Scrammed 0
3 52 Burnup Core Average ND/MPU 73h.58 8,82h.lh Region Average ND/MTU A (INNER) 7hh.67 8,666.70 2h,208.51 B (MIDDLE) 811.22 9,936.91 16,696.01 C (OUTHt) 6h7.72 7,615 55 7,615.55 ZIRCAICY TEST ASSDELIES 995.h2 12,239.63 12,239.63 e
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