ML19351E198
| ML19351E198 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 11/25/1966 |
| From: | YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML19351E196 | List: |
| References | |
| NUDOCS 8011260140 | |
| Download: ML19351E198 (18) | |
Text
_ _ _ - - _ _ _ _.
usf,,,
M - M.
gilo copy
>i
(
p-)
l YANKEE NUCLEAR POWER STATION OPERATION REPORT NO. 70 For the month of OCTOBH1 1%6 O
amb 4o'
/fAA 78
,)
e: 28 (U
.d
~
v d
G r..,c, /
,,f~~;,:iq&by g A
Q
'9's;g; y
\\ f b
4 s
- ~..
a% +A fe 2
o9 f
Q
'Y ge;, c
. /
g9
,(,/
c)
(P Submitted by YANKEE ATOMIC ELETRIC COMPANY Boston M:ssachusette November 25,1966 s o m eo mo
__w0
t O
This report covers the operation of the Yankee Atomic Electric Company plant at Rowe, Massachusetts, for the month of October,1966.
/
s The " stretch-out" operation of Core V centinued from the be-ginning of the reporting period unti October h at Ohh6 hours when the plant was taken off the line for the Core V VI refuelirg and maintenance outage. At the end of Core V operation plant load was 128 MWe, The total electric generation for Core V was 1,Jkh,$09,200 KWh, and during this period the reactor availability f actor was 98.15% and the overall plant operating factor was 93.72%, including the coastdown period when rated capability is not attainable.
After ADC operator examinations, physics tests, and safety valve testing on the hth, plant boration and cooldewn were started. Th9 cool-down was completed on the morning of the 5th and the vapor container was purged.- The vapor. container was then opened and inspectors from the International Atomic Energy Agency removed the seals which had been placed on the missi.'.e shield on November 9,1965 during the start of Core V
( )
operation.
v For the next week work was concentrated on the stripping of equipment from the reactor head and preparation for head removal and shield tank cavity flooding.
Because of generally high levels in the vicinity of the reactor head, lead shielding was placed around the venti-lation annulus to reduce radiation levels in the eorking area. A further reduction was obtained by flushing the control rod drzve mechanism housings
,r' with the application of a vacuum to the control rod vent connections. The s
()
head was removed on the 12th, and before it was stored on the railroad car it was flushed with the 2h-probe flushing device first used during the previous refueling.
After the removal o'~ the reactor head, the shield tank cavity was flooded and the necessary reactor vessel internals were removed to allow access to the reactor core. On the 15th the interchange of control r-rods was started. The 2h latch-joint control rods were individually re-(3 moved and replaced by unitized absorber-follower assemblies. On the re-
_J placement assemblies, an inconel clad silver-indium-cadium absorber section is attached to a zircaloy follower section by a welded inconel-to-stainless steel adapter. This unitized construction will eliminate the latch-joint wear problem which has been encountered in the past.
Following the interchange of control rods, the component inspec-tion program was initiated. Inspection of the eight shim rods revealed wear in the spring vane joints ara the center pivot pin, especially on those rods located in the vicinity of the vessel inlet nozzles; the four shim rods nearest the inlets were Interchange with the shim rods nearest the outlets. The three neutron sources were in excellent condition; the blank vane was moved from the north to the east position, a new source was installed in the west position, and the west and east sources were recycled in the south and north positions. The thermal shield joint clamps in the southeast and northwest positions were inspected with the fifty foot borescope and found to be in good condition with no changes in spacing having occurred since installation during the Core IV-V re-fueling outage.
s
< l
')
The fuel handling operation was started on October 19 Two zircoloy test assemblies had been cyclea through Core V operation and were scheduled to be recycled in Core VI.
On each assembly, however, it was noted that the stainless steelwrapper clips were cracked. The two zircaloy elements were therefore not re:ycled, but were replaced by two stainless steel clad assemblies which hri bean gcled through 3ra IV and Core V..
The complete interchange of fuel van completed in less than two days. The final Core VI fuel conf 2guration is described in the Design Changes _ section of this report, On the evening of the 2h t, the reassembly of reactor internals was started.
All installation work went smoothly, including the latching of the control rod drive shafts, which has always given trouble in the past.
During the Core IV-V refuelin2, a lead weight tube was placed on
.each drive shaft to aid in the latching process.
The use of additional weight did not. improve the latching operation, so further investigation led to the modification.of the universal handlarg tool in April and July, c()
1%6. The modifications may have been successful, because, with a weight tube on each shaft, all rods were latched w2th the universal handling tool and no problems were encountered. However, the success of the oper-ation may have been due to the condition of the rod latch joint, since the 2h rods were new.
During the installation of the dr2ve shaft locking caps, it was noted that nine of the caps could not be locked an place because the lock-ing pin on the drive shaft had either sheared off or had worn. Rather (Y
thin risk the possibility of loose locking caps during Core VJ operation, the nine caps were removed.
The shaf ts which have no locking caps are No. 1, 2, 3, h, 5, 7, 8, 11, and 2he The reactor head was placed on tha reactor on the 2hth, and efforts through the remainder of the period were concentrated on clean-up of the shield taak cavity; installation and tensioning of the vessel head (D
studs; and the installation of ina: ore instrumentation connections, cabling,
'd and ventilation ductwork on the reactor head. At the end of the reporting period, cold control rod exercises had been completed with no abnormal operations noted, and plant heat-up was in progress preparatory to the 2h-hour hydrogen effusion wait.
During the preparations for head removal, it was noted that the south in-core instrumentation thimble had defective threads at the attach-ment point for the protective cap. The protective cap is designed to keep water from entering the thimble, thus protecting the thermocouples during the period when the shield tank cavity is flooded. An attempt was made to seal the protective cap, but when the in< ore structure was removed it was noted that the ccp did not remain on the thinble. With the cap removed, the integrity of the thermocouples is dependent upon an inner gasketed fitting which is attached during these periods in place of the thermocouple insulttion hold-down ring.
Aftertherefuelingnoevidenceofwaterwasnotedwithintheir$er fitting, and all thermocouples maintained a normal read-out.
s One of the major work items during the Core V-VI refueling period was the removal, inspection, and overhaul of No. 2 main coolant pump. Throughout Core V operation the tearing water tenperature and cooling dentnd of this pump had been higher than nonnal, a condition indientive of thermal barrier gasket leakagh The purp work was per-formed at the plant site by Yankee perscrnel, in conjunction with assistance by Westinghouse engineers. On Octcber 7 the punp was re-moved from the main coolant loop and placed vn the outdoor dacontamin-ation pad. Subsequent dismantling and inspection revealed cutting of the thermal barrier gasket, as suspected; some wear of the shaft and bore in the vicinity of the thrust runner; and minimal bearing wear.
The thermal barrier gasket, thrust runner, and thrust shoes were re-placed and some metal crushing of gasket mating surfaces was lapped until smooth and uniform. After a complete cleaning of all parts, the pump was reassembled, a:xi on October 29 it was reinstalled in the main coolant loop. Bolt tensioning on the main flange and stator cap was completed on the 31st and the pump was operated during plant heat-up r1 with no apparent problems.
J As a result of the presurizer inspection during the Core IV-V refueling (see Operation Reports No. 58 ar.d 59) a pressurizer surveillance program was initiated in order to establ:sh reference conditions for evaluation of the cladding integrity. Worx on the surveillance program continued through most of the refueling period, depending on access to the pressurizer vessel. The following is a summary of the work perfc med at the site during the Core V-VI refueling period: The resistance
(
welded clad surface of the vessel head was dye penetrant tested and
'/
photographs were taken; ultrasonic testing was performed en the north-east-south crea of the vessel at a distar e of 17.5 to 19 9 feet belcw the manway flange; the area in the northeast quadrant of the vessel head was ultrasonically tested and radiographec; two boat samples were taken for metallurgical analysis; and the solencia relief line to vessel joint was radiographed.
I' A portion of the reector vessel head cladding was inspected
\\'
and dye penetrant tested. No cracks were observed in the stitch cladding or in the weld deposit cladding.
The No.17 control rod drive mechar. ism and travel housing sssembly was removed from the reactor head for inspection. The mechanism was dismantled and no adverse conditions were noted in the operating parts of the assembly. Some slight wear was noted on a washer which provides a bearing surface for other parts, but which is not an operating part itself.
The 1966 vapor container penetration testing program was initiated during the shutdown period. Gasketed and valved penetrations were tested at a minimum pressure of 3h.5 psi using soap-bubble techniques and prcssure de-cay measurements. Among those penetrations successfully tested during the period were the electrical penetrations (25% scheduled sampling); emergency manway; air purge inlet, outlet, and by-pass valve penetrations; air partic-ulate monitor lines; service air line; component cooling line trip valve; and the vapor container booster puma line penetration. The vapor container equipment hatch was not designed to be tested in this manner, and was there-fore inspected and sealed under cognizant supervision, using a predetermined inspection and bolting procedure.
.h.
Representatives of the Interri.tional Atomic Energy Agency h
were on-site periodically throughout the reporting period to follow the handling of fuel and maintain their continuing fuel inventory.
- As reported in Operation Report No. 69 (September,1966).
higher than normal activ..ty had been detected in the west culvert system.
The source of this activity was traced to a leaking relief valve in the safety injection tank heating system (thence to the culvert system via the floor drains). A continuation of the culvert sampling, at an in-creased frequency, indicated that the culvert water activity had return-ed to normal levels within 2h hours.
Thereafter, activity levels remained normal until October 15 Subsequently, culvert water activity became sporadically higher than normal throughout the remainder of the reporting period. Inspection of the plant revealed no abnormal conditions. Consequently, the drainage system from the primary auiliary building was suspect, having been previously contaminated. Small amounts of activity were apparently being carried into the culvert by liquids passing through a contaminated floor v
drain system.
Inasmuch as investigation had revealed no plant abnormalities, the usual procedure of calculating the activity release on the basis of a known amount of effluent from a particular system could not be followed.
Therefore, the release computation was based en the specific activity and flow-rate of the culvert water for the time period between each sample.
(
3 Throughout the culvert sampling program two samples were normally taken ij simultaneously for verification of results by an outside laboratory. The activity from those samples for which quantitative verification was ob-tained was averaged with the activity for the samples analyzed by Yankee.
Based on the foregoing the total release for the year, to date, is 319 me, and the specific activity of discharged west culvert waters, averaged over the year, is less than MPC.
(~',
Action to eliminate this source of possible low level contamin-L' ation has been initiated. The floor drains from the primary auxiliary building are being isolated from the culvert system and a sump tank and pump installed for transfer of drainage to the waste disposal system.
t
4
_g.
Plant Shutdowns e
Shutdown No. 85-5-6 lo-h-66 scheduled core v - core VI refueling shutdown Plant Nhintenance The following is a list of the major itens performed by the plant staff, augmented by personnel of the New England Power Service Company, during the month of October, 1966:
1.
The main generator was electrically tested and dismantled for inspection. The exciter assembly and the rotor were removed, and the inspection and electrical checks showed the unit to be in generally good conuition. A few end turns had evidence of corona and several slot wedges had worked loose. There was no sign of excessive vibration.
Repairs consisted of wedge tightening, painting of insula-tion, general cleaning, and gasket replacement.
)
2.
A new outer moat ring was installed in the shield tank cavity.
The former ring was bolted around the inner and outer circum-ferences, and required considerable personnel radiation ex-posure during the installatien and removal procedures. The new ring is welded around the outer edge, thus reducing the exposure problem.
3.
The check valve in No.1 main coolant loop was inspected and
( 3
\\
j found to be in good condition; the disc hinge bushing and block assembly had been repaired in April,1966. The check valves in loops No. 2, 3, and h were inspected and were not in as poor condition as the valve in loop No. I had been, but did require the installation of new bushings.
h.
No.1 and 2 circulating water pumps were repaired. The lower r
bearings were replaced; the scored shafts were sleeved; and
(_N
)
the pitting of the end bells was filled with an epoxy compound, then ground smooth.
5 A periscope and elevator mechanism were installed in the spent fuel pit for Westinghouse personnel to use in detailed inspec-tions and fuel rod work on the two zircaloy test fuel assemblies.
6.
The vital bus inverter was repaired and returned to service.
The unit had been out of service due to the failure of the generator inboard bearing; replacement of the generator end bell was required.
7 Seven rod position indicating coil stacks were inspected and repaired; the replacement of several coils was necessary.
8.
An extension was installed on tne spent fuel pit manipulator crane fuel Landling tool. The tool had become engaged in a fuel assembly at the start of the fuel handling operation. To prevent reoccurrence and subsequent delays, an extension tool head was engaged on the crane tool and was operated by manually rotating the tool boom.
. 9 Blank seal discs were seal-welded into the upper and lower llll vapor container manhole penetrations. The manholes are not used and are gasketed penetrations; the discs will eliminate the manholes as a source of air leakage from the vapor con-tainer.
- 10. Slight cavitation on the first stage impeller of No. 2 con-densate pump was repaired by brazing and grinding; new lower bearings were installed,
- 11. Two bleed orifices were replaced; eacS allows a flow of 25 gpn in the main coolant bleed line.
12.
Primary and secondary valves were repacked as necessarye
- 13. Steam shields were installed over those tubing sections in the main condenser where steam elo. ion had been noted.
n
( ')
lh. Stean shields were installed en the six centrifix support bars in the titrbine moisture separators.
Pitting of the shell in the vicinity of the centrifix was ground, filled with weld material, ground smooth, and painted.
Instrumentation and Control The following is a list of major items performed by the plant
(_
staff, augmented by personnel from the Instrument Department of the 3
'J Connecticut Yankee plant, during the month of October,1966:
1.
At the start of the shutdown, the nuclear instrumentation channels were recalibrated in preparation for AEC operator license examinations, and Vis1 corder equipment was connected for control rod drop timing traces, centrol rod mechanism current and voltage traces, and reference vibration traces
(~')
at selected points on the main coolant pumps.
sv 2.
The annual operational test of the vapor container trip valves was performed.
3 The solder-type neon lights were removed from the secondary scram sequence panel and sockets were installed for plug-in type high-intensity neon lamps, h.
The gain control potentiometers on the nuclear instrumentation power range channels were replaced as part of the preventive maintenance program, 5
The n' agram of neutron detector cable replacement was continued witt he replacing of cabling to selected BF3 detector and ion cP ser thimbles.
6.
The feedwater control valves were inspected and found in good condition; gaskets and packing were renewed as necessary.
. \\
)
7.
The speakers in the vapor container audio system were
~'
tested and installed in directional enclosures. A new channel was added to the system with the installation of a speaker near the valves in the vicinity of the radio-active pipe chase.
8.
All primary plant instrumentation channels were recali-brated. Feedwater control system and condenser level instrumentation was recalibrated.
Reactor Plant Performance The re utor power level at the end of Core V operation was hh3 Wt and the core burnup was 8892.6 WtD/MTU. Following the plant shut-down on October h, control rod drop tests and physics tests were performed.
Rod drop times were normal and the all-rods-out boren concentration
,s (j'
approximately ten hours after shutdown, was 226 ppm at h850 F.
The Core VI fuel replacement program was started at 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> on October 19 A problem with the fuel handling tool on the spent fuel pit manipulator crane cau-'d a delay of two hours at the start of the program, but once started, the fuel handling moved smoothly to completion with interruptions only for the inspection of selected fuel assemblies and for 1/M core shutdown evaluation tests. The final Core VI fuel
_( X assembly was positioned at 13h5 hours on the 21st, and 1/M data on the V
fully loaded core showed an average core shutdown value of approximately 6% AK/K shutdown.
The inspection of fuel assenblies which had seen service during Core V operstion revealed unexpected crud accumulations, especially near the upper portions of the fuel elements. The first three refueling shut-downs were made from an unadjusted pH condition and the fuel assemblies
(,
were clean, with little or no crud accumulation. The Core IV-V shutdown was made from a high pH condition with an am:eniated main coolant system, v'
snd the crud accumulation on the fuel assemblies was very high. It was therefore assumed that the Core V-VI shutdown from unsdjusted pH would result in only minor crud accumulations on tha fuel assemblies. The crud levels on the inspected fuel assemblies, however, were judged to be approximately the same as those seen during the Core IV-V refueling. A peculiarity was noted in that the crud which had accumulated on the ferrules in the highly crudded regions of the inspected assemblies was of a light orange color, as opposed to tne dark coloring which has been noted previously.
Aside from the crudded appearance, the stainless steel clad assemblies which were inspected were in good condition. On one assembly, which had been cycled only through Core V, a foreign object was dangling from the lower nozzle assembly; the object was removed, but has not been identified.
S
. The two zircaloy test assenblies wers given a routine inpsection in the shield tank cavity. It was noted on both assemblies that some of the right-angled clips which secure the stainless steel wrapper had broken or cracked along the bend line, and one assembly had some minor wrapper deformation at grid locations near the center of the assembly. The two assemblies were subsequently removed to the spent fuel pit ani given a de-tailed inspection by Westinghouse personnel. The assemblies were apparently in good condition otherwise, but were not recycled in Core VI.
The east flux wire entrance port tubes and the incore portion of the flux wire thimbles were examined. There has been no noticeable change in the corrosion pattern within the entran:e port tubes since the previous inspection during the Core IV-V refueling, and no change in the wear pattern on the incore section of the tubec.
A portion of the outside surface of the reactor vessel was in-spt:ted by borescope through a hole in the seal ring attached to the vessel (V
fla age. The surfaces which were accessible for viewing down to and including three support legs are in excellent uncorroded condition.
Secondary Plant Performance The condenser was cleaned immediately after shutdown. The clean-liness of the tubes was above average, indicating that the chemical treatment of circulating water, which was started in Aubust,1966, is beneficial in c
l
')
the reductio: of condenser tube fouling. The external surfaces of the con-denser tubes were subsequently inspected and steam erosion was noted on some tubes where erosion had been noted previoasly.
No. 2 circulsting water pump was removed for inspection.
The in-let bell had a ring of pitting arourgi the inner circumferential surface which is in close proximity to the impeller, the shaf t was scored on one side only at the lower journal, the lower bearing was scored and the water passages g(')
along the bearing surface were plugged. After repairs were effected, No.1 circulating water pump was removed and found to be in the identical condition.
No. 2 condensate pump was inspected, Slight cavitation was noted on the first stage impeller; otherwise, the pump was in good condition.
The high pressure and low pressure turbines were not dismantled during this outage, but were inspected by access through the manways. The high pressure turbine was clean and in good condition; the low pressure turbine had some slight erosion of the stellite tips on the outer edge of the last row of blades.
The internals of the two turbine moisture separators were similar in appearance. All centrifix support bars had steam erosion. Except for some pitting of the shell in the vicinity of the centrifix and slight erosion in the turning vanes in the elbows at the high pressure steam entrance, all other conditions were excellento
9 No. 3 and No. h steam generators were inspected and found in goed condition. The feedwater distribution ring bangers were in good
' w.,
condition; they had been modified durirg the Core IV-V refueling shut-down.
The shell was removed from No, 3 f eeewater heater, and it was noted that there has been a continuation of the fretting wear between the tubes and the baffle. Six tubes required pluggi ug.
Chemistry Prior to the shutdown, 83,000 gallons of dilution water were added to the primary system for reduction of main coolant tritium activity; the decrease was from 1 3 ue/ml to 0.05 ue/ml. After the system boration (2190 ppm) and pressurizer safety valve tests, the coolant crud level increased to 161 ppm. The crud concentratien de-creased to 1.0 ppm by the time safety hjaction water was added to the shield tank cavity.
During the refueling period the boron concentration in shield tank cavity and shutdown cooling water varied between 2590 ppm and 26h0 ppm. The gross specific activity of these waters decreased from h.1 x 10-2 ue/ml to h.3 x 10-3 ue/ml at the time the shield tank cavity was emptied.
Crud level during this period varied between 0.51 ppm and 0.27 ppm.
Health and Safety
()
No shipments of radioactive waste or spent fuel were made during the month of October,1%6.
During October the waste disposal liquid releases totaled 20h,000 gallons containing 1.hh me of gross beta-gamma activity and 255 8 curies of tritium. Gaseous waste releases during the same period totaled 131 me of xenon-133 and 3.17 curies of tritium.
J 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 47 uc and 2 curies, respectively.
An additional 2.87 caies of tritium in the form of a vapor was purged from the vapor container to the primary vent stack during October.
The airborne tritium concerjtration in the vapor container at the time of reactor shutdown was 2 x 10-> uc/cc. The purge fan was started on October 5 at 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> and run almost continuously throughout the period.
Three hours, 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and 2h hours, after starting the purge, the concen-trations were reduced by factors of ten, 100, and 1000, respectively.
Thereafgerforthebalanceoftheperiod,theconcentrationwasbetween 2 x 10- uc/cc and 8 x 10-0 uc/ce, except for the period of cavity flood-ing when it was 3 x 10-7 ue/cc.
t
. In the shield tank cavity prior to reactor head removal, radi-ation levels were 1-1 3 r/hr at the top of the lower section of the reactor
(
head ventilation annulus with the upper section removed; 30-h0 ar/hr general area between the reactor head and the cavity walls; and 130-150 mr/hr at the tops of the reactor studs.
The addition of one inch of lead around the ventilation annulus reduced radiation levels to 100-150 mr/hr outside the ventilation annulus; 30-50 mr/hr at the studs; and 10-25 mr/hr general area.
Congamination levels in the cavity before flooding were 50,000 -
100,000 dpn/ft. After flooding the shield tank cavity, radiation levels on the charging floor at the edge of the cavity, were higher than previ-ously. experienced by a factor of ten. The higher levels were accredited to correspondingly higher crud levels in the cavity watece After the eavity.was drained, radiation levels were generally higher ?.han usual in the cavity, due to adherence of the crud to the cavity walls.
kvels before and after cleanup of the walls and floor were as follows:
Cavity Condition & Radiation Level Dry - Before Dry - After C;vtty Iocation Cleaning-Maat Dry Qeaning-Moat Flooded North-Contset wall, 3' up 350 mr/hr 350 mr/hr Midway from wall to head 200 115 Contact with head 350 125 J
East- (same conditions as 150 125 North) 250 125 250 150 South- (same conditions as 180 125 North) 250 llo 250 160 J
West- (same conditions as 150 150 North) 250 90 200 130 Reactor Head Flange 300 - 500 200 - 300 Stud Hole Annulus 100 - 200 100 - 150 Samples of vapor container atmosphere were collected in the shield tank cavity and on the charging floor during reactor head removal, and were analyzed for radioactive gases. There were no detectable gaseous constitu-ents in any of the samples collected.
t
~ The pressurizar was opened for inspection of the internal cladding j
and radiation levels were 10-200 mr/hr at the top of the compartment and
/
200 mr/hr in the pressurizer manway. A survey inside the pressurizer showed 500-600 mr/hr, 5 feet down from the manway; 1200-1500 mr/hr,10 feet down; 900-1100 mr/hr, 15 feet down; h000-5000 nr/tr, 20 feet down; and 6000-6500 mr/hr at the 25 foot level. Hosing down the heater bursiles and raising the water level to 16 feet reduced the above radiation levels by a f actor of three.
Representative. radiation levels during inspection and maintenance of main coolant check valves were 150-200 mr/hr contact with the sides of the valves; 100-120 mr/hr contact with the tops of the valves; 150-200 mr/hr one foot above the water level (valve covers rcmoved); 7-9 r/hr one inch above the water level in the valves; and 50-150 mr/hr in the general work area around the valves.
Attempts were made to flush out the control rod drive mechanism housings. Prior to removal of the reactor head, a vacuum flush was per-(
formed in all mechanism housings. Radiation levels at points between the housings, just above the bells, were reduced from 2-5 r/hr to 0.6 - 3 r/hr.
Levels on contact with the in-core penetrations were reduced from 0.6 - 2 5 r/hr to 0.35 - 1.5 r/hr. A second flush was ineffective. After the reactor head was removed from the vapor container, further attempts at reducing radiation levels from the mechanism housings were mada utilizing water lances. Levels at the bells were reduced from 0.9 - 1.6 r/hr to h00 - 900 mr/h".
Iccal hot spots on the sides of the housing were not affected by
(,
the flushing.
V The No. 2 main coolant putop wa= removed for inspection and main-tenance. The impeller section was deconvaminated using a two step, two solution immersion process. The radiation level at the center bottom of the impeller was reduced from h r/hr to h50 m-/h%
Radiation exposure doses, as measured by film badge, for the month p
of October,1%6 were:
C/
Yankee Personnel Average accumulated exposure dose 11h5 mrem.
Maximum accumulated exposure dose 2598 mrem.
N. E. Power Service Co. Personnel Average accumulated exposure dose lh51 mrem.
Maximum accumulated exposure dose 2021 mrem.
Design Changes 1.
Modifications to Pressurizer Gas Phase Sampling System A.
The existing pressurizer capillary vent was re-routed W
and connected to the existing high pressure vent line to the low pressure surge tank.
s
. B.
The upper pressurizer penetration of the narrow range level detector was modified to allow sampling through the penetration, and a capillary vent was installed between the modified penetration and the existing high pressure vent line to the low pressure surge tank.
C.
The high pressure vent line was tapped and a line was extended from the tap to the contaminated sample sink in the primary auxiliary building.
These modifications will allow the sampling of the pressurizer gas phase 4thout a vapor container entry; the sample can te valved directly to the radicchemistry sample sink. The r.ew sample tap allows sampling of the gas phase at a point which is closer to the operating water level of the pressurizer, thus allowing an investigation of suspected gas stratification within the gas phase.
Q Authorization for this design chinge was requested in Proposed Change No. 72 submitted August 1, 1966.
Saptember 7,1966.
A.E.C. approval was granted on 2.
Installation of Absorber - Follower Assemblies Twenty-four unitized control rod-follower assemblies have been installed in the reactor core to replace the twenty-(' '1 four latched absorbers and followers which were in the core V
during Core V operation. Each unitized assembly consists of an inconel elad, silver-indium-cadmium absorber section and a zircaloy follower section joined by a rigid adapter section. In the new assembly design a welded joint re-places the snap joint in the former design, thus eliminat-ing the latch joint wear problem.
('
Authorization for this design charge was requested in U
Proposed Charge No. 73 submitted August 31, 1966.
A.E.C.
approval was granted on September 29, 1966.
3.
Core VI Core VI was loaded in the same regional pattern which was used in the previous cores.
Thirty-six new h.9h% enriched assemblies are located in the outer region. Thirty-six assemblies, which were originally h.9h% enriched, have been moved from tne outer reg.
of Core V to the intermediate region of Core VI.
Four assemblies, originally h.1% enriched and previously cycled through Cores IV and V, have been located in the central region.
The original Core VI loading arrargement has scheduled the two zircaloy test assemblies to be recycled in the central region. When the wrapper damage was discovered on the zircaloy assemblies, the loading arrangement was changed to that described above.
s
. Authorization for this design change was requestLed in Proposed Changes No. 7h and 76 submitted September 1, 1966 (J
and October.20,1966, respectively.
A.E.C. approval was granted on September 29,1%6 and November 1,1966, re-speetitely.
h.
Flanges have been installed on the two pressurizer safety valves, PR-SV-181 and H1-SV-182, and on the mating piping connections in the pressurizer compartment. Leakage through the safety valves at operating conditions has forced the plant to cool down for safety valve repair on several occasions in the past. The use of flanged connections on
.the two valves will allow the valves to be removed from the piping for insertion in a test stand. By externally testing the valves for leak-tight seating before plant heat-up, the necessity of a cooldown for valve repairs is minimized. The flanged connections are seal-welded after the valves are installed.
U 5
Feedwater Line )bdifications A U-tube loop soal connection has been installed in the eight-inch feedwater piping to No. 3 and No. h steam generators.
The loop seal is located between the connection to the vessel and the line which penetrates the concrete shield wall. This modification was made in an effort to reduce the severe water-(m hammer condition which has occurred in the past during periods
(
)
of low feed flow to the steam generators. The water-filled loop seal will prevent the feeding of a steam and water mixture directly into the steam generator. A similar installation is proposed for No.1 and No. 2 steam generators.
In conjunction with the loop seal installation, a steam line is being inst,:lled from upstream of the steam by-pass valve to the No. 1 feedwater heater.
No. 1 feedwater provides eg) preheating of the feedwater by the use of extraction steam from the turbine.
Daring hot stand-by conditions, when the turbine is not operating, no steam is available for the feed-water heater. The new steam line installation will provide steam to the feedwater heater under these conditions, thus preheating the feedwater when there is low flow to the steam generaters and reducing the temperature differential between the water in the steam generator and the water in the feedwater line; the net effect will be a reduction in the tendency toward water-hammer in the feedwater system. Work on this change was in progress at the end of the reporting period and will be com-pleted during the first week of November,1966.
t
e I
-lh-6.
Scram Auxiliary Relay Supervisory Light
,x s
' s_,)
A neon lamp has been installed on the main control board to supervise the integrity of the coil circuit of the scram auxiliary relay. The supervisory light will indicate that power is available to the relay coil and that the circuit through the coil is continuous, thus proving coil integrity.
'4'his installation is a result of the investigation which followed the feilure of the turbine solenoid trip coil on November 26, 1965 Operations Attached is a summary of plant operating statistics and a plot of daily average load for the month of October, 1966.
,G
\\s)
(x i)
N
'llL
p
,r >
b'
(
/
YANKEE ATOMIC EIETRIC COMPANY -- OPERATING
SUMMARY
OCTOBER, 1966 EIETRICAL
}0 NTH YFAR TO DATE Gross Generation WH 9,905,000 1,143,617,500 6,13h,h58,h00 Sta. Service ( Wile Gen. Incl. Losses)
IGIH 750,83$
70,0hh,958 hl6,h57,h52 Net Generation WH 9,15h,lo$
1,073,$72,$h2
$,718,000,9h8 Station Service 7.3S 6.12 6.79 Sta. Service (While Not Gen. Incl. Iosses)
OTH
$96,h7h Sh7,7hl 23,089,319 Ave. Gen. For Pt> nth (7h5 hours)
W 13,295 Ave. Gen. Running (76.77 hours8.912037e-4 days <br />0.0214 hours <br />1.273148e-4 weeks <br />2.92985e-5 months <br />)
W 129,022 PIANT PERFORMANCE Net Plant. Efficiency 26.85 25.h3 28.hh Net Plant Heat Rate Bru/WH 12,710 12,00h 12,000 Plant Operating Facter 7.63 86.26 70.99 Reactor Plant Availability 10.86 89.o$
S2.82 NUCLEAR
}0 NTH CORE V TOTAL Hours Critical HRS 80.88 i,7 %.72 h3,72$.68 Times Scrammed 0
$2 Burnup Core Average WD/MTU 68.50 8,892. ch Region Average WD/MTU A (INNER) 68.53 8,735.23 2h,277.Oh B (MIDDLE) 76.h8 10,013.39 lo,772.h9 C (OUTER)
$9.75 7,675.30 7,67$.30 ZIRCAIDY TEST ASSEMBLIES 92.$6 12,332.19 12,332.19
ATOMIC C COMPANY DAILY AVERAGE IDAD for OCT03Dl, 1966 200 -
n E
2 o
i di 150 -
N T
~
M
~
100 -
U M
ca
~
50 -
Shutdown No. 65-5-6 0
I i
i i
g i
e i
i l
I i
i I l 1
I I
g to 15 20 23 30 DAYP i
1
4
\\
, R CORE VIRGION IDCATIONS
(
REIr)N C REION B 1
RMION A O
O G
.g a w
.