ML19351E005
| ML19351E005 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 06/20/1962 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| References | |
| NUDOCS 8011250397 | |
| Download: ML19351E005 (13) | |
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. YANKEE NUCLEAR POWER STATION t
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IQ OPERATION REPORT NO.17 Q'
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.;'s Submitted by YANKEE ATOMIC ELECTRIC COMPANY Boston Massachusetta June.20, 1962 O
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This report covers the operation of the Yankee Atomic Electric Company plant at Rowe, Massachusetts for the month of May 1962.
For the first fifteen days of the month the plant remained in continuous operation. The plant power level and average main coolant temperature which were 89 MWe and hh30F with all control rods withdrawn at the beginning of the period continued to decrease gradually as a function of extended Core I operation.
On May 16, at 6:00 AM the turbine throttle valves were manually tripped with the reactor scramming automatically. The shutdown, for test purposes, was initiated at a power level of 81 MWe (h350F T ave.).
It also marked the first separation of the generator from the line since December 21, 1961, a continuous operating period of approxinately 3500 hours0.0405 days <br />0.972 hours <br />0.00579 weeks <br />0.00133 months <br />.
Selected control rod drop times were measured during the scram and core decay heat generation data were acquired following the scram.
[v,h On May 16, at 2:19 FM the unit was rephased to the line and by 9:20 PM a power level of 97 MWe had been established with all control rods fully with-0 drawn and a main coolant average temperature of h52 F.
The Xenon decay following the shutdown permitted attaining a power level higher than that possible prior to the shutdown. At 11:15 PM on May 16, the power level was manually reduced to 83 Ede for test purposes.
p On May 17, at 9:15 AM the four main coolant by-pass valves were opened l
V and a 50 gpm purification flow rate was eatablished. Operating in this manner l
provided a flush of the main coolant by-pass lines which previously had exhibited relatively high activity levels after periods of prolonged plant operation. The on line flush was maintained for approximately twenty four hours.
At 8:00 AM on May 18, the turbine throttle valves were manually tripped at a power level of 10 MWe. This shutdown terminated Core I power operation and with it the refueling outage commenced. The final conditions of Core I operation were:
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MWe 78.h l
T ave.
h29.5 All control zods fully withdrawn All turbine control valves fully open Equilibrium xenon for 260 MWt i
Concurrent activities both in maintenance and physics testing followed the plant shutdown. Physics tests included xanon decay follow, moderator pressure and temperature coefficient determination and control rod worth measurements.
Test activities were coordinated with operations activities such that boration, cooldown and depressurization of the primary system permitted testing as well m
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as preparation of the reactor for refueling. On May 2h, the core was released from critical operation, all end of core life testing having been completed.-
The primary ~ coolant ~at this' time was depressurized and at a temperature of N1000F with a boron concentration of 1205 ppm.
Considerable. progress had been made on secondary plant maintenance projects by the end.of the month.
No.' 3 feedwater heater modifications had been completed including a hydrostatic? test on the heater while No. 2 feedwater heater modifications were nearly completed. At the same time all four turbine control valves had been removed and the high pressure casing and rotor had been lifted.
Immediately following the plant shutdown of. May 18, preparations within the vapor container began. Equipment (air ducts, insulation, cable trays) was removed from the shield tank cavity before embarking.on a thorough cleaning of the cavity. _ Core instrumentation flux wires and thermocouples were disconnected
. p at the reactor head and removal of control rod drive coil stacks was started.
By-the-end of the period h6 of the.52 reactor vessel head closure nuts and studs v
had been removed.- Six remained in place to seal the primary system until lifting of the reactor head'.
Pressurizer safety valves were tested shortly after the shutdown with both valves operating as prescribed. With the main coolant temperature and pressure conditions (3500F, 2500 psi) existing during the safety valve tests, p extensive leakage occurred at No.1 and No. h main-coolant pumps flanges. Some 4
.() evidence of leakage appeared at the flange of No. 2 pump while No. 3 pump showed no signs of leakage.. The leakage resulted from the inability to adhere to the normal main coolant pressure-temperature relationship. Following the valve i
testing there was no discernable leakage at the flanges when inspected visually at a main coolant pressure of 1600 psi.
On May 2h,~ abnorns1 vibration of No. 3 charging pump was detected. In the course of investigating t,he problem,, the pump suction strainer was removed O. and found to be plugged with matted paper shreds. In order to check the normal charging path to the main coolant system, the No. 2 charging pump suction strainer was removed and showed no evidence of foreign matter. Since the only conceivable point where paper could enter the system was through the boric acid mix tank, a.
strainer was installed in the suction of the boric acid transfer pump following which the solution in the tank was recirculated through the pump. Examination of the temporary strainer revealed an accumulation of shredded paper. The boric acid mix tank was subsequently drained, cleaned and refilled with a new solution..
Apparently a paper bag was dropped into the mixing tank in the: process of-adding boric acid to the tank. As an immediate precaution, a temporary screen was placed across the fill opening in the mixing tank. A permanent screen
.will be provided in addition to which boron addition to the mixing tank will be ac:cmplished with a metallic container.
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7 No reactor scrams arising from non-standard or emergency conditions occurred during May. Two plant outages were recorded for the period with the second outage still in effect at the end of the period.
Shutdown No. h8 5/16/62 - an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 19 minute scheduled outage for test purposes.
Shutdown No. h9 $/18/62 - a scheduled outage for reactor refueling.
Maintenance Maintenance activities during the first half of the period were primarily routine in nature. Considerable effort was devoted during this time to insure equipment readiness where possible for the refueling operation and turbine inspection. Temporary neutron counting instrumentation was installed in the vapor container together with an audible neutron count speaker in the control room.
v Following the plant shutdown on May 18, the plant maintenance staff, augmented by thirty temporary personnel embarked on an extensive primary and secondary plant schedule. The followiilg summarizes the major maintenance and refueling preparations to the end of the month:
Prinary Plant Q
1.
Checked main coolant stop valves for packing leakage - some leakage was evident on three of the eight stop valves.
2.
Tested the pressurizer safety valves. Both valves were found in good working order.
3.
Repaired insulation on No. $ and No. 6 pressurizer heater groups.
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Removed missile shield and neutron shield blocks.
$. Removed air ducts, insulation and cable trays from the shield tank cavity.
6.
Completely inspected the Vapor Container polar crane.
7.
Prepared the fuel manipulator crane.
E.
Installed control rod joint disengaging mechanism in shield tank cavity.
9.
Installed fuel handling jacking mchanism and removed fuel chute blank.
10.
Removed, painted and reinstalled neutron detector channel covers.
The lead shielding in the covers was also removed.
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- 11. Remove'd h6.of 52 reactor-head closure nuts and studs. The remaining 6 nuts and studs were left in place until just prior to lif ting the _ head.
-12.
Removed four control rod drive coil stacks. Further removal of coil stacks was_ delayed as a result of the shielding they afforded to personnel working in the vicinity of the reactor _ head.
- 13. Removed flux wire and thermocouple connections at the reactor head.
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Painted all carbon steel parts in T,he shield tank cavity.
- 15. Removed the Vapor Container equipment hatch cover.
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16 Set up two temporary nuclear instrumentation channels in tue main m
control room.
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- 17. Installed a high neutron count alarm siren and audible neutron count speaker and amplifier in the Vapor Container.
- 18. Installed new BF 3 detectors in thimbles 1, 2 and 6.
The existing BF 3 detector in thimble h was hot replaced.
- 19. Installed eight new flux wires in the core instrumentation system.
Secondary Plant 1.
Insta11ed four away braces at the expansion loops on the main steam lines in the Vapor Container.
2.
Inspected the steam side of the condenser with no sign of erosion evident.
-.O 3
Inspected and cleaned four transformer oil coolers.
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- h. Removed shells and completed internal modifications on feedwater heaters No. 2 and No. 3 Modified steam supply lines were also in-stalled on these heaters. No. 3' heater was hydrostatically tested following the completion of its modification. Revision of the heater drain will complete-the work on No. 2 heater.
5 Removed the turbine control valves and servo motors.
- 6.. Removed turbine high pressure casing and blade rings. Lifted high pressure turbine spindle.
7.
Moved generator exciter, purged generator of hydrogen and prepared' to remove generator rotor.
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8.
RemovedL secondary steam generator safety valves for off-site testing.
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' V ; Chemistry Prior.to the two plant outages, main coolant chemistry conditions were normal with no detectable oxygen, a specific activity of 5.1 x 10-2 to 5.5 x 10 :pc/ml and a crud level of approximately 0.15 ppm. 'Ihe iodine - 131 specific activity was 1.7 x 10-h c/ml.
p Main coolant gas analyses before and after the ion exchangers indicated:
Before Ion Exchanger After Ion Exchanger A-h1 1.h x 10-1 pc/cc gas 6.7 x 10-2 pc/cc gas Ie-135 1.8 x 10-2 pc/cc gas 1.0 x 10-2 pc/ccgas Kr-85m 8.5 x 10-3 pc/ccgas 1.5 x 10-3 pc/cc gas O
xe-133 1 5 x 1o ve/cc see 2 9 x 1o-3 ve/c= 8 e Increases in the main coolant I-131 and I-133 activity were note
'during the plant loading on May 16. The I-131 activity which was 1 7 x 10- pc/ml before the shutdown increased to w 1.8 x 10">h p/ml during the plant loading.
pc The corresponding I-133 activities were 6.8 x 10-c/mland2.68x10-3 pc/ml.
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. Following the plant shutdown of May 18, the secondary side of the four steam generators were blanketed with nitrogen..The nitrogen blanket results in i
an average of 28 ppm excess N H 2 h n the water phase.
The main coolant crud level before shutdown on May 16,'was 0.11 ppm.
Following the scram the level increased to 0.62 ppm. In the ensuing hours with loop by pass valve manipulation the crud level increased Ibrther to 1.9h ppm.
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After rephasing the unit on May 16, and establishing a 50 gpm purification rate, the crud level was reduced to 0.78 ppm. The crud level continued to decrease and by May 21, stood at 0.1h ppm. Purification was stopped late in the day on May 21, and boron injection was initiated with a gradual increase in crud level.
On May 2h, the shutdown cooling system was placed in operation with boration
.of the system continuing. After approximately four hours of shutdown cooling flow and with the boron concentration atN 200 ppm, the crud level was 1.hh ppm.
Seven hours later the crud' level had increased to 6.95 ppm.
Still later on the 4
- same day with a-boron concentration of~1200 ppm the crud level had increased to 15.9 ppm. With the. boron concentration remaining at 1180 - 1200 ppm the; crud level decreased to 10.55 ppm on May 25, and to 2,69 by May 28. Connection of the shutdown cooling system to a cation ion exchanger brought the crud level
~ down to 0.2h ppn by the ; end of the period.
Approximately four days after the refueling shutdown the main coolant specific activity wa.s 7.2 x 10-4 pc/ml (crud level 0.1h ppm). Two days laterg
-(May 2h) with the main coolant boron concentration being increased and with the shutdown cooling system in operation,' the specific' activity was 8.9 x 10-3 pc/ml
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(crud level 6.95 ppn).. On May 28,- with the main coolant fully borated and cooled -
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q (T ave. ~1000F) the specific activity had increased to 2.2 x 10-2 pc/ml b).
(crud level 2.69 ppm). Dy the end of the period the main coolant specific activity was 2.6 x 10-3_pc/ml (crud level 0.2h ppm, main coolant cold and borated to ~ 1180 ppm).
Reactor Plant-Performance Core reactivity calculations indicate a loss in reactivity of 0.15% d f as a result of the plant shutdown on May 16, Sinilar reactivity losses have. accompanied previous shutdowns during Core I operation.
Following the plant shutdown on May 18, a series of end of core life physics tests were conducted.
Included in the test program were the detemination of moderator temperature and pressure coefficients of reactivity in a borated and boron free core, core xenon follow, control rod worth and boron concentration required to control the reactor in a "just critical" condition at operating temperature with all control rods withdrawn.
O While complete test results are not available at this time the follow-V ing have been determined:
1.
'All Rods Out Baron Concentration The main coolant boron concentration required to control the reactor in a "just critical" condition with all control rods fully withdrawn was found to be 2h0 210 pp (corrected to main coolant conditions of $1h0F T ave., 2000 psi, (d
xenon free core with equilibrium samarium). This concentration compares with a N
start of core life figure of approximately 1707 pm (51hT, 2000 psi, xenon and samarium free).
2.
Moderator Temperature Coefficient The following tabulation includes the results of moderator temperature coefficient determinations throughout Core I life. The values are for zero p
power based-on a least square, straight line fit of data acquired in a boron and xenon free core over a main coolant temperature range of approximately h300F to 530 9 T average.
EFPH @ 392 MWt d 9/ d T @ $1h F*T< average
(-3.10 1 0.07) x 10-b d 9/ F 0
1852
(-2.91 1 0.03) x 10-b dp/0F 387h
(-2.91 1 0.02) x 10-h g g/op 6hh5
(-2.8h 1 0.05) x 10-h g p/or 10676
(-2.8h 2 0.0h) x 10-h g g /op O
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Moderator Pressure Coefficient The following are results of moderator pressure coefficient deter-minations as a function of Core I life. The results are for zero power based on a least square, straight line fit of data acquired in a boron and xenon free core over a pressure rande of 1800 to 2200 psi.
EFPH @ 392 MWt 8f/6P8Slh0, 2000 psi F
4 0
(+ 2.98 2 0 30) x 10 Af/ psi 4
8
(+ 2.8710.03) x 10 89/ psi 132
(+ 2.80:1 0.02) x 10-6 g p / p,1 1852
(+ 2.h7 3 0.0h) x 10-6 g g / p,i O
387h
(. 2.h510.06) 10-6 ae/,.1 6hh5
(+ 2.71 1 0.10) x 10-6 g p / p,i 10676
(+ 2.65 2 0.09) x 10-6 g pf poi h.
Control Rod Drop Time Measurements y
Rod drop and dash pot closures times were measured on each of the twenty four control rods. No measurable cL=ge in drop time was observed from comparable start of core life tests.
Turbine Plant Performance During the latter part of May, podifications were completed on No. 3 feedwater heater. A complete description of the modifications is' included under the section "DESION CHAN3ES".
An inspection of the steam side of the condenser indicated no erosion or cutting of the condenser tubes.
Health and Safety Liquid waste containing 31h pc was discharged from the plant during May. No gaseous or solid wastes were discharged from the plant during the period.
At all times'the concentration of waste products discharged or shipped from the plant was well below the maximum permissible.
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.The following contact-radiation levels were measured during May at a power level of 86 MWet Location Radiation Level on Contact No. 1 Charging Pump 8mr/hr No. 2 ' Charging Pump 30mr/hr No. 3 Charging Pump 10mr/hr Charging Line (in pipe chase) 7 mr/hr Main Coolant' Bleed Line (in pipe chase)
$0-100mr/hr Activity Dilution Decay Tank 20-100mr/hr Waste Holdup Tank 10-70mr/hr Gas Surge Drum 0.02mr/hr Shutdown Cooling Pump 70-100 mr/hr Shutdown Cooling Exchanger 20mr/hr No. 1 Purification Pump Drain Line 100mr/hr No. 2 Purification Pump Drain Line 100 mr/hr
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l Low Pressure Surge Tank Discharge Line 250mr/hr Low Pressure Surge Tank Bottom 1.5 r/hr-Ion Exchange Pit 0.1mr/hr Radiation levels in the shield tank cavity shortly after the plant shutdown on May 18, and during the removal of insulation and duct work from the vicinity of the reactor head were 1 to h mr/hr in the general area,15 to h0 mr/hr on contact.with the ventilation ducts and 100 to 150 mr/hr-over the (7 tops of the control rod drive mechanism coil stacks. Contamination in the 2
shield tank cavity was less than 100 dpm/ft.
Radiation levels in the shield tank cavity and around the reactor head during the removal of reactor closure nuts and studs-were:
General Area 1-h mr/hr Reactor Head (on contact) 10-20 mr/hr Control Rod-Drive Mechanism Coils (on contact).
50-200 mr/hr v
Control Rod Drive Mechansim Housing after Coil Removal (on contact) -
.100-h00mr/hr Contamination in the shield tank cavity ranged from less than 100 to 2
1000 dpm/ft.. At the same time contamination levels on the charging floor ranged from100toh00dpm/ft2withacorrespondingradiationlevelof0.5mr/hr.
Radiation levels on contact with the bottom section of the closure
- studs after their removal were approximately 0.3 mr/hr. No measurable radiation was detected at the upper section of the studs or on the closure nuts.
Operation of the' Shutdown Cooling System resulted in a contact radiation
~ level increase in the ~ shutdown cooling heat exchanger from 30 mr/hr to 60 mr/hr.
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Radiation levels measured on contact with the Low Pressure Surge Tank
(#g) approximately eleven days after. the shutdown weres.
Inlet -
12 mr/hr
. Centerline of. Tank 6-60mr/hr Top of Tanki
'8-15 mr/hr
. Bottom of Tank 100mr/hr. tor /hr(onepeakspotof50r/hr)
Loop radiation levels measured at a' distance of one foot approximately 5 days after shutdown indicated:
Loop 1
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'Stm Gen. R se 20-150mr/hr 20-55mr/hr 20-60mr/hr 20-80mr/hr By Pass Valve 60-90mr/hr h0-55mr/hr 50-60 mr/hr 50mr/hr MC Pipe (Th) h0-80mr/hr 200-250mr/hr 100-160mr/hr 100-h00mr/hr MC Stop Valve'(Th) 90mr/hr 80-100~mr/hr 70-80mr/hr 60-85mr/hr pd Loop Fill Chemical Injection Valve 70-100mr/hr h5-60mr/hr 200-275mr/hr 35-h5 mr/hr MC Pipe Tc 50-85mr/hr h0-60mr/hr 100-135mr/hr 30-50mr/hr MC Stop Valve Tc 30mr/hr 27mr/hr 70-90mr/hr 30-35mr/hr Loop Drain Valve 200-500mr/hr 120-h00mr/hr 200-250 mr/hr 0.35-2.0 r/hr General Area Levels 30-80mr/hr 15-90 mr/hr 20-100mr/hr 10-80mr/hr O
The maximum personnel exposure as measured by film badges for the month of April 1962, was 210 mr while the average for all station personnel was 10 mr.
Continuous monitoring of off-site airborne activity during April indicated plant levels consistent with pre-operational values.
Design Changes V
The following minor changes in plant design were completed during May:
1.
External and internal modifications were made to No. 3 feedwater heater. The external modification consisted of providing an additional steam supply inlet to the upper section of the shell by extending the existing steam supply line and adding an, inlet nozzle to the heater. The internal modifications consisted of adding deflecting baffles opposite the new steam inlet nozzle and also opposite the existing bottom steam inlet nozzle.. Also included in the changes was the installation of an additional internal drain..The modifications were made to effect improved steam distribution within the hester in order to improve its performance and also to provide for increased heater capacity in anticipation of a possible increase in the plant licensed power level.
O 2
n= ries che versea cometructie= or deoentem1=ette= ved e-completed. The reinforced concrete pad with a carbon steel sur-face plate will be.used for. decontamination of the spent fuel shipping cask.
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3.
Addition of a tubular evaporator reboiler, a cyclone separator and a reboiler circulating pump to the radioactive liquid waste treatment system has been completed. The original electrode evaporator has been lef t in position; however, its electrical connections have been disconnected.
The inability of the electrode evaporator to produce processed water of sufficient purity led to the above system modification.
This change is in accordance with Proposed Charge No.17 submitted on February 1,1962, and approved by the A.E.C. on March 20, 1962.
In Plant Training Four Sponsor company engineers, one Stone & Webster engineer and three representatives of the Selni nuclear project commenced assignments at the plant
(~'s during May.
'w; Changes in ooerating Procedures During the month the normal plant operating instructions covered in sections 50h A 1, and 50h A 2, 50h A 3, 50h C1, 50h C 2, 50h D h, 50h D 7, 50h E 1 and 50h F 1 were revised and consolidated into three simplified sections designated 50h A 1, 50h A 2 and 50h C 2.
This change is in accordance with
^ Proposed Change No.18 submitted on February 1,1962 and approved by the A.E.C.
(V on May 16, 1962.
Plant Operations Attached is a plot of daily average plant load and a summary of plant operating statistics for the month of May 1962.
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YANKEE ATOMIC EECTRIC COMPANY - OPERATIKI SIM!ARY MAY 1962 MON 7H YEAR TO DATE EECTRICAL WH 3h,550,800 369,173,700 1,330,521,000 Oross Generation Sta. Service (While Gen. Incl. Losses)
WH 3,h69,h38 30,028,3h9 107,560,b31 KWH 31,081,362 339,1h5,351 1,222,960,569 Net Generation Station Servios 10.Ch 8.13 8.08 Sta. Service (While Not Gen. Incl. Losses)
IGAI 9h3,851 9h3,851 11,035,569 Ave. Gen.
For Month (7hh HRS.)
W h6,h39 Ave. Gen.
Running (h07.7 HRS.)
W Bh,7h6 PLANT PERFCRMANCE 27.h9 28.78 Net Plant Efficiency Btu /WH 12,hl$
11,858 Not Plant Heat Rate lb.87 1h.05 Ibs. Steam / Net KWH-Circulating Water Inlet Temp.
0F h2 Maximum or 3h Mi n4 --
35.96 68.00 68.59 Plant Operating Factor M0fffH CORE I TO DATE NUCLEAR 7
262 262 Times Critical HRS
$35.h2 13,247.h3 13,2h7.h3 Hours Critical 0
30 30 Times Scresumed HRS 267.5 8628.5 t$628.5 Equivalent Reactor Hours @ h85 E t NWD/mtU 259 83h9 83h9 Average Burnup of Core Control Rod Position at Month End Equilibrium at Group 1 Rods out-inches p
Group 2 Shut Down Group 3 For Refueling Group h Group 5 Group 6
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