ML20248L408
| ML20248L408 | |
| Person / Time | |
|---|---|
| Site: | Monticello, Prairie Island  |
| Issue date: | 09/01/1992 |
| From: | AFFILIATION NOT ASSIGNED |
| To: | |
| Shared Package | |
| ML20248L403 | List: |
| References | |
| NUDOCS 9803200186 | |
| Download: ML20248L408 (24) | |
Text
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8
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ANNUAL REPORT REVIEW OF METEOROLOGICAL DATA 1991 MONTICELLO AND PRAIRIE ISLAND STATIONS September 1, 1992 Prepared for:
Northern States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401 Prepared by:
.McVehil-Monnett Associates, Inc.
44 Inverness Drive East Building C, Suite B-Englewood, Colorado 80112 Project Number 164-92, 1
9003200186 900306 PDR ADOCK 05000263 P
i
1.0 INTRODUCTION
l McVehil-Monnett Associates, Inc.
(MMA) performs a detailed
)
review each year of summarized annual meteorological data from the monitoring systems at the Prairie Island and Monticello Nuclear Generating Stations. The review includes joint frequency tables of meteorological parameters from each measurement height, and tables of relative concentration (X/Q) and deposition (D/Q) at various distances and directions.
The purpose of the review is to provide an independent quality assurance check of meteorological data and related dispersion parameters for the sites.
~
The annual review includes a general check of all parameters for completeness and reasonableness, comparisons to previous years data to identify any trends or notable changes in values, trial calculations of X/Q and D/Q values for comparison to the tabulated
- values, and consistency checks between different
- heights, parameters, and measurement systems.
This report presents results of the review of meteorological data for calendar year 1991.
i f
1 1
I 2.0 MONTICELLO METEOROLOGICAL DATA Figures 1-4 and Tables 1 and 2 show comparisons between 1991 statistics from the Monticello meteorological tower and the same statistics for prior years. The distributions of wind directions at each measurement height are in good agreement with previous years (Figures 1-3).
There'was an increased frequency of east southeast winds in 1989, and a decrease in north and ncrth northwest winds; these trends are obviously real since they can be seen at all three measurement heights.
~
The consistency between winds at three different altitudes for 1991 is illustrated in Figure 4'.
The good agreement confirms that wind direction data from all three heights were relatively complete and accurate.
All four wind direction graphs demonstrate the predominance of southerly and northwesterly winds that is expected at Monticello, based on regional climatology.
1 Table 1 provides data on wind speed measurements for 1991.
The recorded wind speed frequencies at each height are consistent with historical experience and theoretical expectation.
Table 2 presents data on the reported frequency of stability classes.
Data are generally consistent with past years; there is an indication of slightly more neutral (class D) stabilities in 1991 with a corresponding reduction in unstable and stable classes.
The difference is shown for both delta T measurement intervals and is not unreasonable.
It is not a result of higher wind speeds, since speed data in Table 1 indicate no significant change.
It is likely that the higher frequency of neutral stability was the 2
l
Wind Direction Frequency Comparison Monticello 10 meters 12 11 i
10 9
8 7
///
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J 5
4 n
3 N
NE E
SE S
SW W
NW NNE ENE ESE SSE SSW WSW WNW NNW D 1986-1989 o
1990 a
1991 t
TICURE 1 3
t Wind Direction Frequency Comparison 5
l Monticello 43 meters 12 11 L-1e k
-9
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1 A
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2 1
N NE E
SE S
SW W
NW j
NNE ENE ESE SSE SSW WSW WNW NNW i
O 1988-1989 o
1990 A
1999 I
4 t
i FIGURE 2 I
4
e i
Wind Direction' Frequency Comparison-Monticello 100 meters 12 11 s
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Lla mrx-y NNE ENE ESE SSE SS#
WSW WNW NNW D
1986-1989 o
1990 a 1991 l
e FIGURE 3 5
I Wind Direction versus Height i
Monticello 1991 l
11 10 p
s, i
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t s
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4 My 3
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N NE E
SE S
SW W
NW NNE ENE ESE SSE SSW WSW WNW NNW i
D 10 meters o 43 meters A 100 meters l
FIGURE 4 6
(-
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I TABLE'1 KEASURED WIND SPEED DISTRIBUTIONS AT MONTICELLO (PERCENT OF'ALL OBSERVATIONS) 0)
1986-89 1p_9,p,U 3 1991 10-meter height 1 - 3. mph 16.6 16.2 15.9 4 - 7 mph 42.2 41.9 42.8 8 - 12 nph 29.7 30.0 30.2 13 - 18 aph 10.5 10.5 10.2 19 - 24 mph 1.0 1.3 0.8
> 24 mph 0.0 0.0~
0.0 43-meter height'##
1 - 3 mph 5 '. 2 3.5 4.4 4 - 7 mph 22.1 19.9 21.3 8 - 12 mph 39.1 41.0 39.7 13 - 18 mph 25.2 26.1 25.5 19 - 24 mph 7.2 7.4 8.0
> 24 mph 1.2 2.0 1.2
'9 100-meter height 1
'3 mph 3.1 2.3 3.1 4 - 7 mph 13.1 12.1 13.4 8 - 12 mph 25.0 24.8 23.0 13 - 18 mph 34.0 34.7 32.9 19 - 24 mph 19.3 20.1 21.3
> 24 mph 5.6 6.1 6.3
- UI 1990 and 1991 data average of A and B trains (2) 43-meter historical data for 1987-9 and 1990 only i
7
)
TABLE 2 l
OBSERVED FREQUENCY OF STABILITY CLASSES AT MONTICELLO (PERCENT OF ALL OBSERVATIONS) l 1989 1990I 1991I Based on DT 100 A
4.4 1.4 0.6 B
4.9 3.7 1.8 C
5.9 5.7 4.4 D
40.6 40.8 48.0 E
28.0 32.3 30.0 F
10.0 11.0 11.O 6.3 5.1 4.3 G
Based on DTMID A
16.0 11.4 7.4 B
3.1 2.9 2.7 C
6.7 6.3 6.3 j
D 27.0 27.4 33.8
{
E 27.2 31.6 31.4 F
10.2 11.3 10.4 G
9.8 9.2 8.1 I
I I
l I'I i
1990 and 1991 data average of A and B trains
~
l l
l 8
result of increased cloudiness during 1991.
Annual climatological
- data'for Minneapolis indicates above average sky cover for 1991.
7 Data recovery was good during 1991. All individual parameters
- were recorded,in excess of 90% of all hours for the year.
Joint frequency -tables (combining wind speed, wind direction, and' stability class) also all contained greater than 90% complete data, except for Channel B (back-up data) for 100 m height. Most tables were more than 95%
complete.
Data recovery satisfies NRC-
-requirements.
It is concluded from the data review that 1991 l
l Monticello data are accurate and representative, and are appropriate to characterize site meteorology and atmospheric dispersion.
O' 9
l.
j
3.0 PRAIRIE ISLAND METEOROLOGICAL DATA l
1991 data ~from Prairie Island are compared to prior years in Figures 5-8 and Tables 3-5.
The wind direction distributions L
l (shown in Figures 5-7) are highly consistent with past year's data.
l l
A slight increase in east southeast winds in 1991 is shown, which agrees with data from Monticello.
The prevailing wind directions l.
(east southeast and west northwest) are determined by a combination of regional weather patterns and the orientation of the Mississippi
~
River Valley at Prairie Island.
These prevailing directions show clearly in the 1991 data.
I Figure 8 compares wind directions at the three Prairie Island measurement heights.
It should be recognized that the 22 m wind data are recorded at the back-up met tower which is sited closer to the western valley slopes than is the primary (10 and 60 la) met tower.
Thus, the difference in the 22 m direction distribution is not surprising.
As shown in Figure 7,
the back-up tower wind directions are perfectly consistent with past years, though 4
slightly different than the primary tower directions.
Table 3 provides wind speed distributions for all wind measurements.
The 1991 data show excellent agreement with past years.
Stability class frequencies are presented in Tables 4 and 5.
Again there is good consistency with past data.
The relative frequencies of each stability class are perfectly reasonable for the Prairie Island climate and the two different stability l
classification methods.
i 10
f-Wind Direction Frequency Comparison Proirie Island 10 meters 13 I
12 1-1%
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%/P 3
o NE ENE ESE SSE SSW WSW WNW NNW D 1986-1989 o
1990 a 1991 FIGURE 5 11
.A
Wind Direction Frequency Comparison Prairie Island 60 meters 13 a
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4 3
MF 2
N NE E
SE S
SW W
NW NNE ENE ESE SSE SSW WSW WNW NNW D 1986-1989 o
1990 a 1991 FIGURE 6 12 w-_ ----
Wind Direction Frequency Comparison Prairie Island 22 meters 14 13 2l
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( X U/
3 3 vr w
mV 2
N NE E
SE S
SW W
NW NNE ENE ESE SSE SSW WSW WNW NNW D 1989 0
1990 A
1991 i.
FIGURE 7 13
L Wind Direction versus Height Prairie Island 1991 13 f\\
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N NE E
SE S
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NW NNE ENE ESE SSE SSW WSW WNW NNW D 10 meters 0 22 meters a 60 meters
}
l FIGURE 8 14 E________-____.__________
TABLE 3 3
MEASURED WIND SPEED DISTRIBUTIONS AT PRAIRIE ISLAND (PERCENT OF ALL OBSERVATIONS) 0)
1986-89 199.0_U 3 1991 10-met'er height 1 - 3 mph 20.8 20.7 20.9 4 - 7 mph 37.2 35.0 38.6 8 - 12 mph 31.2 32.4 29.6 13 - 18 mph 9.6 10.1 9.9 19 -;24 mph
-1.2 1.3 0.8-
> 24 uph 0.1 0.1 0.0 60-meter height 1 - 3 mph 9.4 9.2 8.7 4 - 7 mph 25.9-24.2 26.6 8 - 12 mph 35.2 33.5 35.1 13 - 18 mph 22.2 23.9-21.7 19 - 24 mph 6.0 7.1 7.1
> 24 mph 1.3 2.1 1.1 22-meter back-up'*)
1 - 3 mph 16.2 14.7 16.6 4 - 7 mph 35.8 34.6 37.4 8 - 12 mph 35.4 34.8 32.1 13 - 18 mph 11.2 13.2 12.2 19 - 24 mph 1.4 2.1 1.6
> 24 mph 0.1 0.3 0.0 U3 1990 and 1991 data for 10 and 60 meters average of A and B I
trains (2)
Historical data for back-up tower for 1989 and 1990 only 3
15
r-l TABLE 4 I'
L OBSERVED FREQUENCY OF STABILITY CLASSES AT PRAIRIE ISLAND i
(PERCENT OF ALL OBSERVATIONS) 0' 03 1986-89 1990 1991 A'
4.3 3.2 4.0-B 3.6 3.8 3.2 C
5.0 4.9 4.2 D
40.9 40.7 40.8 E
35.7 36.9 38.3 F
7.7 7.8 7.2 G
3.0 2.8 2.3 U3 1990 and 1991 data average of A and B trains I
16 l
I
[
TABLE 5 PRAIRIE ISLAND STABILITY CLASS FREQUENCIES AS DEFINED BY SIGMA-THETA (PERCENT OF ALL OBSERVATIONS) 1989 1990 1991 (A train)
(A train)
Primary Tower 10-meters A
17.4 18.1 17.1 B
10.8 11.9 11.8 C
24.4 18.0 26.3 D
36.3 37.2 38.6 E
8.3 4.1 4.2 F
0.7 0.2 0.5 G
2.2 0.5 1.4 Back-up Tower 22-meters A
11.7 14.3 15.2 B
9.5-10.2 10.9 C
24.4 28.8 29.5 D
36.6 37.0 35.7
~~
E 10.8 8.6 8.2 F
1.5 0.6 0.3 G
5.6 0.6 0.2 I
17
r..
j l
l.,
i l
As usual, the Prairie Island data set shows 100%
data I
recovery.
The' 1991 meteorological' data are judged
- complete,
~
t accurate.and representative.
i
')
l
.I 1
i e
l 18 1
t-l H, j
y.-
<4.O CONCENTRATION AND DEPOSITION COMPUTAT7.ONS
,1 Also included in the annual meteorological information i
l submitted for review are printouts of relative concentration (X/Q).
j and ' deposition (D/Q) for both ' plant sites.
These dispersion parameters are derived from the year's meteorological data by site-L" specific computer programs at each plant.
In past years, review of X/Q and D/Q data has consisted mainly-of' checking for consistency with past year's
- results, and l
consistency between directional variations and observed wind.
]
directions'for the year.
For a few specific cases, X/Q and D/Q were calculated by hand and the results compared to the computer J
printouts. Hand calculation of the dispersion parameters is.rather tedious and complicated, and only spot checks were made'to confirm that computer recults were reasonable.
Though no specific errors in X/Q and D/Q data have ever been identified, the past hand calculations were inadequate to confirm that all computer results were co2.Tect ; they only indicated that results were generally reasonable.
Some questions have remained unanswered on the exact basis and correctness of all computer results, and on apparent differences between hand and computer results.
3 I
For the 1991 data review, more extensive calculations have I
been made, using equations and parameters taken directly from Offsite Dose Calculation Manuals (ODCM's) and MIDAS documentation.
Calculation routines were developed to facilitate detailed lt calculation of X/Q and D/Q for various distances and directions.
l The review calculations cannot agree precisely with the on-site l
19 I
I o
'9.
computer. results,. since the., former use summarized ' annual' data gcv i
t' ables,'while the latter calcul'ations are based upon the. original L
' hourly observations.< ; However, results indicate that agreement can be obtained within one or two percent, which is certainly adequate.
to. confirm that the. computer printout values of X/Q 'and ' D/Q 'are l
representative of the year's' meteorology.
Le Because of the new review calculation routines' and additional effort expended on' the dispersion parameter review, we can, for the, '
first time, directly confirm for 1991 that X/Q and D/Q values for.
]
.most cases are correct and appropriate.
However, some question remains for two sets of computations.
The results and conclusions of the review'.are presented Delow.
(1)
Prairie Island calculations are relatively
)
1 straightforward: they assume a ground-level release with building wake, corrections, and the useL of 10 m. wind, observations.
Our results agree very closely withfthe L.
computer printout results for both X/Q and D/Q. -Changes from 1990 are slight and consistent with the small l
changes in annual meteorology.
It.is concluded that all Prairie Island X/Q and D/Q results for 1991 are correct and representative.
I It should be.noted that in past reviews, we were unable to duplicate 1989 X/Q data at Prairie Island.
Those data still appear to. be inconsistent with all oth'er years l.
i.
1986-91.
l 20 L
(2)
Monticello computations were carried out in detail for the stack release point at 100 m
height.
The
- l i
calculations included plume rise and utilized observed 100 m winds.
Results agreed quite well with the printouts submitted by the plant, for both X/Q and D/Q.
Results are also consistent with 1990 data (as at Prairie
- Island, 1989 results appear questionable).
We are satisfied that 1991 stack release tables are correct, and the confidence level in this conclusion is high because of more extensive and exact computations.
(3)
Calculations for the reactor vent telease at Monticello are the most complex; NRC guidance requires c mixed-mode (wake split) calculation routine for releases at heights near the building height.
After calculations using
~
several different assumptions and data sets, we were able to obtain reasonable agreement with the computer values of vent release X/Q by using the mixed-mode equations, a vent exit velocity of 6.1 m/s at 43 m height, and 1991 wind data from 43 m.
These parameters and assumptions are consistent with data in the Monticello ODCM.
However, use of the same assumptions and methodology for calculating vent release D/Q produced relative deposition values nearly twice as large as those given in the printouts.
The only way that we could reproduce D/Q results to any degree was by using 10 m wind data for all hours; the use of 10 m winds does not appear reasonable 21
F.
j-for a 43.m release height, and is inconsistent with the successful methodology'for confirming the vent release X/Q data.
There thus appears to be an inconsis'tency between the vent
. release X/Q and D/Q results.
The 1991 data are not greatly i
different from past years, so the problem, if any, exists in the calculation methodology.
Possible. reasons for the inconsistency include:
stack-release parameters different from-those given in
+
the ODCM.
I a misunderstanding on our part of-the MIDAS calculation l
procedure an error'in the software equations or stored tabular data L
In this connection, it would be very helpful for - future reviews if a copy of all input parameters (option selections, specification of meteorological data file, stack parameters, etc.)
could be provided along with the X/Q and.D/Q outputs.
By
)
l
. confirming these variables and options, the reviewer could better j
j define the specific methodologies used for each calculation.
l-t i
22
L
(
)-
5.O
SUMMARY
AND CONCLUSIONS All meteorological data for 1991 from Prairie Island and Monticello have been reviewed in detail and found to be in good-order.
It is concluded that. the data. presented for, review are accurate, complete, and representative.
l-X/Q and D/Q data for both stations for 1991 were also analyzed
)
in detail; extensive hand calculations were performed to check for 1
proper calculation methods and use of input data.
All Prairie Island results were confirmed, as were all stack release data from
~
Monticello.. For the Monticello vent release, the X/Q results could
)
be duplicated with acceptable agreement, but the D/Q results could not, except by making apparently unrealistic assumptions.
It-is I
recommended-that further checking 'be done prior to next year's review to determine the exact procedures, equations, and parameters 1
used in the computation of reactor vent dispersion parameters.
-With the possible exception of the vent release data for Monticello, all X/Q ' and D/Q results for 1991 are judged to be accurate and representative.
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._-_____.____-____-_a