ML13196A188
| ML13196A188 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 04/12/2012 |
| From: | Balsam B Office of Nuclear Reactor Regulation |
| To: | Crocker J US Dept of Commerce, National Oceanographic and Atmospheric Administration |
| References | |
| FOIA/PA-2013-0135 | |
| Download: ML13196A188 (11) | |
Text
Craver, Patti From:
Balsam, Briana Sent:
Thursday, April 12,2012 1:01 PM To:
Julie Crocker
Subject:
RE: Pilgrim: NRC's complete responses to 4-9-12 NMFS questions Attachments:
Hartwell and Mogolesko 1977.zip Reference 2 of 4.
From: Balsam, Briana Sent: Thursday, April 12, 2012 12:56 PM To: 'Julie Crocker' Cc: Logan, Dennis; Susco, Jeremy; Smith, Maxwell; 'jeganl@entergy.com'
Subject:
Pilgrim: NRC's complete responses to 4-9-12 NMFS questions
- Julie, I attached the NRC's completed responses to the questions on Pilgrim that you sent in your April 9 email to follow-up on our partial response dated April 10.
I will also be forwarding several zip files containing the documents referenced in the responses in subsequent emails. I tried to send them all as one zip folder, but it seems as if my agency's email attachment size limit is a bit higher than yours-the last email I was able to send, but it came back undeliverable. All of the references should also be publically available in our ADAMS system also, and I have included the accession number for each in the attached responses, so that would be another way for you to access those documents if email doesn't work.
Briana Briana A. Balsam Biologist Division of License Renewal Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 301-415-1042 briana.balsam@nrc.gQov
THREE-DIMENSIONAL PIELD SURVEYS OF THERMAL PLUMES FROM SWACDJAXING OPERATIONS AT A COASTM POWER PLANT SITE IN IASSACHUSETTS A.D. Hartwell, Normandeau Associates, Inc., Bedford, NR 03102 and F.J. Mogolesko, Boston Edison Company, Boston, M, 02199, U.S.A.
ABSTRACT Using specially designed temperature profiling equipment, two surveys were conducted during thermal backvashing operations at Pilgrim Nuclear Power Station to determine the spatial and temporal extent of temperature rises above ambient.
Backvashing formed a thermal plume about 5 to 6-ft thick (1.5 to 1.5 m) in front of the intake screenvall.
Maximum observed surface temperatures were 101.0 F (38.3 C), representing a AT of 43.4 F (24.1 C) above ambient.
The frontal zone of the plume spread gradually seaward at about 0.2 kn.
Its outer edge became thinner and rapidly cooled, presumably by advection and turbulent diffusion associated with currents from the reverse pumping and local changes from dissipation to the atmosphere.
Along the intake shoreline, the plume was often less than I ft (0.3 m) thick.
Most of the hot water was dissipated within several hundred feet of the intake with aT's of about 10.0 to 15.0 F (5.6 to 8.3 C) above ambient.
Under the influence of strong southwesterly winds during the second survey, some warmed water was apparently carried beyond the outer breakwaters into Cape Cod Say.
These surveys provided real-time data indicating that the backwashing operation caused a rela-tively thin thermal plume, which spread rapidly from the intake out across the study area and along the seaward breakwater.
Within a few hours these backwash thermal plumes were completely dissipated.
INTRODUCTION Although thermal backwashing is a commonly used technique for control of biofoullng in condenser tubes and intake structures of operating power plants, only limited published information is available on the receiving water temperature structure caused'by such operations. Bos ton Edison Company, Boston, Massachusetts, conducted two thermal surveys of actual mid-summer backvashing operations under varying tidal conditions at Pilgrim Nuclear Power Station during 1977 to establish a synoptic picture of the plume's three-dimensional structure Il].
The Pilgrim Nuclear Power Station, located on the shore of Cape Cod Day in Plymouth, Massachusetts, is'a 655 MW light-water moderated, boiling water nuclear reactor with a onc-through condenser cooling water system.
water used for cooling the condenser is removed from Cape Cod Day through a shoreline intake (Fig. 1).
It enters the intake between two break-waters via a dredged channel which is about 18 to 24 ft deep (5.5 to 7.3 m) at mean low water (MR).
ADH R111 En4
Under normal operating conditions, the water is drawn into the intake by two pumps (designated herein as east and west), circulated through the condenser system and discharged via a surface canal at a rate of about 510 million gallons/day and a AT (difference between the discharge and intake temperatures) averaging 30.0 F (16.7 C).
Condenser tubes are cleaned by backwashing on a I to 2-week interval, depending upon bio-fouling severity.
Generally 45 to 60 min are required to treat each of the two circulating water pumps, with elevated temperatures averaging around 100.0 F (37.8 C).
Occasionally the temperatures peak at from 110.0 F (43.3 C) to 120.0 F (48.9 C),
depending upon the amount of heat treating necessary.
Because plant load must be reduced during backwash-ing, the operation is generally conducted at night during off-peak hours.
METHODS This study conducted by Normandeau Associates, Inc.
(NAZ),
of Bedford, New Hampshire, consisted of overnight three-dimensional temperature and current surveys, supplemented by continuous thermal monitoring.
For the first survey on July 9 and 10, 1977, backwashing began at low water and continued into early flood tide.
During the second survey on July 16 and 17, 1977, backwasling began at high water and continued into early ebb tide.
Both surveys concentrated on the time history of plume build-up and dissipation.
Temperature and depth data were collected at selected stations (Fig. 1) and plotted on board the survey boat using a Naico Model 3100-TD Profiling System (Fig. 2).
Current velocity profiles were acquired using Bendix Model Q-15 current meters and Model 270 recorders.
Precise location was continuously recorded using a Motorola KiniRanger III System with two shore based transponders.
Two Naico Model 200 Digital Field Temperature Recorders were utilized to periodically measure temperature profiles from water surface to bottom at two stations in the intake channel.
The arrays were assembled so they could be moved quickly within the survey area to check thermal anomalies.
in addition, two Naico Model 1001-T Temperature Recorders were installed to monitor water temperatures 1) inside the intake screenwall and the discharge canal, and 2) in ambient receiving waters of adjacent Cape Cod Bay.
Observed temperatures were transformed to true temperatures using regres-sion equations based on calibration data for each respective field instr*ment.
From measurements of ambient near-bottom waters mid channel between the two intake breakwaters (rig. 1), a AT or approximate temp-erature rise above ambient was calculated for each temperature observa-tion.
2 ADH
FIELD SURVEYS Low-water backwash Survey The July 9 and 10 low-water backwash survey consisted of five sampling runs keyed to actual plant operations.
For this survey, NAI's ambient temperature measurements along the bottom of the intake channel started around 49.0 to 50.0 F (9.4 to 10.0 C) and then gradually rose to about 58.0 F (14.4 C) by the time of low water.
Throughout the rest of the night, ambient temperatures continued to rise slowly, reaching about 60.0 F (15.6 C) by the end of the survey.
This rise may represent some recir-culation of the discharge plume toward the intake area because of local winds and coastal currents.
As backwashing was initiated, plant load was gradually brought down.
wa's readings of discharge canal temperatures showed a drop from 87.0 F (30.6 C) to 74.6 F (23.6 C1 Fig. 3).
Next, the vest pump was backwashed from about 0030 to 0119 UST.
The In situ temperature monitors recorded a sudden rime in discharge temperature to about 83.0 F (28.3 C),
followed by a sharp drop to about 65.3 F (18.5 C).
Simultaneously water box temperatures rose quickly to about 104.0 F (40.0 C) and remained at this level for much of the backwashing period (Fig. 3).
As backwashing of the first pump neared completion, discharge temperatures rose again to 83.2 F (28.4 C) and water box temperatures dropped back down to below 70.0 F (21.1 C).
From about 0150 to 0227-EST the east pump was backwashed in the same way with similar backwash temperatures observed for both pumps.
During this backwashing period, discharge temperatures dropped to about 70.6 F (21.4 C),
then rose to 87.0 F (30.6 C) for a short time, dropped back down to about 75.0 F (23.9 C),
and finally rose back toward normal operational levels (Fig. 3).
A prebackwash survey conducted during late-ebb showed surface temperature rises (AT) ranging from 9.1 F (4.1 C) near the offshore discharge to 4.9 F (2.7 C) near the plant intake.
As backwashing sta.rted, the first visible evidence was a sudden rush of hot, turbulent water marked by foam and a steamy vapor right in front of the intake.
With continuing backwashing, the hot water formed a surface layer about 5-ft (1.5 m) thick, which reached temperatures as high as 100.0 F (37.8 C) in front of the intake screenwall.
A distinct frontal zone moved slowly northward (or seaward) away from the intake, bulging in the middle and slightly restrained along shore due to frictional effects.
The water temperatures in the near-surface thermal plume gradually decreased with both distance away from the intake and time, presumably due to evaporative heat loss and dilution (mixing with ambient waters).
3 ADH
At the surface, AT's of 42.1 F (23.4 C) in front of the west pump and 24.8 F (13.8 C) in front of the east pump were observed (Fig. 4).
Within less than 100 ft (30.6 m),
the AT from the iestern pump was 28.0 F (18.6 C) or less.
High AT water hugged the outer breakwater, apparently because of momentum effects and southwesterly winds during the night.
Surface AT's of 10.0 F (5.6 C) and higher were confined to the western third of the intake area between the breakwaters (Fig. 4).
The remainder of the area experienced AT's equal to or colder than observed prior to backwashLng.
At the 3.3 ft (1.0 m) depth level, observed AT's were 23.4 to 24.3 F (13.0 to 13.5 C) in front of the intake.
Within less than 200 ft (61.0 m),
AT's were down to 18.2 F (10.1 C).
Beyond that distance they dropped from 14.8 to 6.7 F (8.2 to 3.7 C).
Near the outer end of the break-waters, AT's were only 2.4 to 3.3 F (1.3 to 1.8 C).
At the 9.8 ft (3.0 m) level, AT's were 4.6 F (2.6 C) or less in front of the intake and 1.2 to 2.1 F (0.7 to 1.2 C) along the dredged channel.
Along the bottom all of the AT's were negative, or colder than conditions at the outer end of the breakwaters.
At Station 6 minimum values were
-4.4 F or -2.4 C (Fig. 5).
The detailed profiles at Station 6 showed that the backwashing from the western pu=V formed a distinct slug or pulse of hot water along the surface, which eventually extended-down to about 7 ft (2.1 m).
The heated effluent apparently took about 15 min to reach and about 75 min to pass the anchored boat in its seaward progression (Fig. 5).
Maximum observed AT at the surface was 22.6 (12.5 C), which represented an actual temperature of 79.0 F (26.1 C).
Near-bottom temperatures were 53.4 to 56.2 F (11.9 to 13.4 C) which represented negative AT's of up to -4.7 F
(-2.6 C).
By about 0119 EST backwashing of the west pu was complete.
At about 0150 EST backwashing of the east circulating water pump started.
As before, there was a sudden surge of hot, turbulent and steamy water at the surface.
Within minutes a thin themzal plume and a distinct seaward-moving frontal zone was observed.
At the surface, AT's were essentially the same as during backwashing of the vest pump, averaging 20.0 F (11.1 C) and more across the western third of the study area, 10.0 to 20.0 F (5.6 to 11.1 C) in the middle, and 5.0 to 10.0 F (2.8 to 5.6 C) across the eastern third.
As before, the highest temperatures were along the outer breakwater.
At 3.3 ft (1.0 m) AT's were 15.5 to 23.4 F (8.6 to 13.0 C) next to the intake and gradually decreased seaward.
Delow this level there was no evidence of the backwash plume, whereas along the bottom AT's remained negative.
At Station 6 the second backwash manifested itself as another pulse of hot water, which was warmer than before (up to 81.1 F or 27.3 C) but slightly thinner and shorter-lived (Fig. 5).
This plume had surface aT's of up to 23.5 F (13.1 C).
Apparently it took about 10 to 15 main for this 4
ADH
4A a u 402 414 O
.41S 02.0
.0 0
0%10 V4
- 41 43 4
o 4*
4Ab r4.
0.4 b
40
.04.
0 0
416 144 4
0Ca o4 S-w4.FAi
-r P 4 "4 tpAa S S 9441
,4*
-1 an
'" 0 a.
a.
g 0
4*C014' an u-I Ii.
I..
0.
6'
'4S U
14' I)6 a',
S A0 r4a a
9-4 0,i 4
16 V-4 gas~~
In SI A
U*1 m
14 S4*
6 SAU m
Temperature measurements from the boat anchored at Station 6 showed that the west pump's backwash plume arrived within 5 to 10 min of the start of backwashing (Fig. 7).
The AT's rose sharply to 14.4 F (8.0 C) or an actual temperature of 69.1 F (20.6 C).
The resulting thermal plume seemed to be about 2 to 3 ft (0.6 to 0.9 m) thick and persisted for almost 90 mnn.
Actual backwashing of the west pump was completed around 0113 EST.
At about 0159 EST backwashing of the east pump started.
Surface AT's were 43.2 F (24.0 C) in front of the east pump and 25.2 r (14.0 C) in front of the west pump.
Elsewhere WT's were generally higher than during the previous sampling run.
Temperature rises of 20.0 r (11.1 C) and more were found across the channel to the outer breakwater.
As before the elevated AT's were observed along the outer breakwater (UT's of 15.0 to 20.0 F or 8.3 to 11.1 C), possibly due to continuing wind influence.
Slightly deeper at 3.3 ft (1.0 n), the temperature distribution was about the same as at the surfacel but deeper down and along the bottom, temp-eratures were much warmer than earlier in the evening.
At Station 6 the passage of the east pump thermal plum was very evident (Fig. 7).
It took less than 10 min for the backwash water to arrive and, as before, it persisted for about 90 min.
The temperatures were slightly higher this time, with the greatest rise occurring after backwashing was complete.
At about 0307 EST backwashing of the east pump was completed and the plant started to return to "normal operation.
Subsequent surveys during the rest of the night showed that the elevated surface temperatures and thermal backwashing plumes persisted for almost 4 hrs in the western portion of the study area and somewhat less in the eastern portion, before dissipating.
Backwashing momentum effects, as well as local winds, seemed to play a role in forcing the warmed water along the outer breakwater and keeping it away from the shore in front of Unit 1 (Fig. 6).
DISCUSSION Each backwashing was first evidenced by a pulse of warmed water at depth from the intake (Fig. 8).
As the pumping continued, the hot buoyant water rose to the surface and within a few minutes formed a warm thermal plume averaging 3 to 5 ft (0.9 to 1.5 m) thick.
Below the plume was a steep gradient to the colder near-ambient waters along the bottom of the intake channel.
During the first weekend survey, the thermal plume foxmed a distinct frontal wone of foam and turbulent, steaming water which could be easily tracked by eye.
Under the influence of the reverse intake flows, the initial jet momentum, the plume buoyancy effect and the localized hydrostatic head in front of the screenwall, the frontal zone moved slowly across the study area.
Along shore and in shallow water, 6
ADH
014 08 A
10'0 r4 r4 0
0 w
0-.
r-18 I
U) i
Fig. 1 Location map showing approximate sampling stations and in aitu instrumentation for the July 1977 Pilgrim Station backwashing studies.
LOWilPWPPk F.,,,
a...
.=
gg uusame tagm I
Fig. 2 Instrumentation set up for field surveys.
8 ADH
410 a
we.
I'S.
G IOKWA".
M 1M9 U JULY10 Fig, 3 Teperature monitor data from the West pI waterbox, the discharge canal and the abient in et umit at Station 28 during backwashing operations on July 9 and 10o 1977,
- Im"AlW is ALYS Aye Fig. 5 Temperature data from an anchored survey boat at Station 6 on July 9 and 10, 1977 shoving actual tperatures and corres-ponding aT's above ambient in degrees F.
Fig. 4 Contour maps of observed temperature rises (aT) in degrees F above ambient during early flood (backwash west pwmp) at surface and 3.3 ft (1.0m) on July 10, 1977.
1
.4 U
- I j.ULY Is TME, EST AULY IT Fig. 7 Teqperature data from an anchored survey boat at Station 6 on July 16 and 17, 1977 showing actual teoperatures and correspon-ding WT's above ambient in degrees F, l1tlMllW(l 0
w Fig. 6 Contour maps of observed teperature rises (6T) in degrees F above lent during early eb (bachsh west pwuy) at surface and 3.3 ft. (1,i) on July 11, 1971.
Fig. 8 Temperature profiles fro Station I during the start of bacbashirq of the east circulating water pmp on July Il, 1977.