ML20204D209
| ML20204D209 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/01/1994 |
| From: | Lin Y, Wan P BECHTEL CORP. |
| To: | |
| Shared Package | |
| ML20204C621 | List: |
| References | |
| M94-2, M94-2-R, M94-2-R00, NUDOCS 9903240149 | |
| Download: ML20204D209 (5) | |
Text
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l CALCULATION COVER SHEET foto)Cer C A 4 e. N o.
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PROJECT JOB NO.
CALC NO.
13HEET 1 Calvert Cliffs Nuclear Power Plant 11865-592-NZA M94 2 l
SUBJECT:
Control Room X/Q Calculations (based on wind tunnel testing)
DISCIPLINE ENVIRONMNENTAL TECHNOLOGY CALCULATION STATUS PRELIMINARY CONFIRMED SUPERSEDED VOIDED DESIGNATION l
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COMPUTER PROGRAM / TYPE YES NO V l
l Pages Cover Sheet 1
Calculation 2
Figures 1
l Tables 1
l Total 5
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pg ORIGINATOR DATE CHECKED-DATE Y.
J. Lin Sept. 19, 1994
,j 6s 1.
PURPOSE Based on the wind tunnel testing results to determine the short-term control room X/Q following accidental chemical releases under stable atmospheric conditions.
2.
BACKGROUND A wind tunnel modeling has been performed by CPP Wind Engineering Consultants for the Calvert Cliffs Nuclear Power Flant to predict air concentrations from accidental radioactive and chemical releases.
Since the CPP wind tunnel simulated a Pasquill-Gifford (PG) stabili t;y identified as "C (slightly unstable)" and "D ( neutral) ", it was necessary to evaluate the X/Q values related to the accidental chemical releases in order to obtain more conservative X/Q values under the stable (F) etmospheric conditions.
For chemical release from North Service Building (release point N), the wind tunnel maximum X/Q value was not adjasted to associate with "F" j
stability in this calculation.
Because release point N is located very close to the air intakes, with relatively short traveling distance the difference in dispersion between "D" and "F" stabilities are expected to be insignificant.
3.
INPUT DATA Maximum one-hour X/Q values due to accidental cher.ical releases (see
-)
Figure 1) are provided by CPP at the air intakes.
Release location Maximum credicted X/O value 3
Warehouse outdoor storage 2.01E-4 s/m 3
Ammonia / Morpholine tank 2.66E-4 s/m 1
4.
METHODOLOGY It is assumed that the dispersion coefficients are function of both background turbulence and local mechanical mixing due to buildings, and can be expressed in the following forms:
= (c.,2 + a,,y ) t/2 (1) 2 ay l
a, = (a 2 + a.2) ir2 (2)
- where, a,y horizontal dispersion coefficient aartociated
=
with background turbulence, m
9 CALCULATION SHEET
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CALC NO.
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DATE Y. J. Lin Sept. 19, 1994 a,y horizontal dispersion coefficient associatert
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with background turbulence, m a,y horizontal dispersion coefficient associated
=
with mechanical turbulence, m a., =
horizontal dispersion coefficient associated with mechanical turbulence, m For simplicity, it was further assumed that local mechanical turbulence is longitudinally and vertically symmetric, i.e.:
a, = a.,
(3)
In order to convert the wind tunnel results to the X/Q values associated with stable conditions the following apprcaches were used.
Mechanical turbulence dispersion coefficients were obtained from the maximum wind tunnel data.
By comparing the test data to the conventional Gaussian equation (see Equation 4), values of a and a, were estimated.
y X/Q = 1/ (fra a u)
(4) y These were then broken down into their respective mechanical and background components using Equations (1) and (2) and the maximum wind tunnel data listed above.
The resulting mechanical dispersion coef ficients were then re-combined with "F" stability background dispersion coefficients to obtain dispersion coefficients representative of "F" stability.
5.
CALCULATIONS The calculation results are provided in Table 1.
Based on the wind tunnel X/Q values and the corresponding PG dispersion coefficients, the associated mechanical dispersion coefficients for releases at P (warehouse outdoor storage) and Q (Ammonia / Morpholine tank) are found to be 32.2 m and 32.9 m, respectively (see Table 1).
Using this set of mechanical dispersion coefficients and the dispersion coefficients under "F" stability, the maximum X/Q values due to accidental chemical release 3
are estimated to be 2.84E-4 and 2.89E-4 s/m, respectively for release at P and Q.
The horizontal and vertical mechnical dispersion coefficients (32.2m and 32.9 m, respectively) are very similar.
Since these values satisfy the assumption of a, lues.= o.,; thus, no adjastment was made in estimating the resultant X/Q va 6.
REFERIINCE
' Wind Tunnal Modeling of the Calvert Cliffs Nuclear Power Plant, CPP.
project 94-1040, prepared for Baltimore Gas and Electric Company, CPP Wind Engineering Consultants, Fort Collins, CO, August 1994.
i CPP Project 94-1040 Cermak Peterka Petersen, Inc.
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Table 1. Mechanical Turbulence Undbr Stable Condtions Wind Tunnel Distance to PG PG Gaussian Mechanical Resultant Release Pt. Stability X/O -
intake (m) Sigma (ay) Sigma (az) X/O Sigma (my) X/O P
C, D 2.01E-04 312 29.5 16.8 6.44L-04 32.2 2.01E-04 l
O C, D 2.66E-04 130 13.1 7.6 3.17E-03 32.9 2.66E-04 P
F 312 11.6 5.8 4.75E-03 32.2 3 2.84E --04 r
O F
130 5.2 2.8 2.16E-02 32.9 2.89E-04 t
Notes:
P - Warehouse outdoor storage O - Ammonia / Morpholine tank PG - Pasquill-Gifford Mechanical turbulence dispersion coeffiencits, Sigma (my) and sigma (mz), are determined by:
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- 1. Sigma (my) = Sigma (mz) i
- 2. Sigma (y) = (Sigma (ay) ^ 2 + Sigma (my) ^ 2)^ 0.5 I
- 3. Sigma (z) = (Sigma (az)^2 + Sigma (mz)^2)^0.5 where, Sigma (ay) and Sigma (az) are the PG dispersion coefficients, and Sigma (y) and Sigma (z) are the dispersion coefficients accounted for both background and mechanical turbulence.
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