ML20127J661

Forwards Comments of Environ Meteorological Research Branch on Plant Facility Description & SAR Vol 1 & 2

ML20127J661
Person / Time
Site:	Monticello
Issue date:	10/26/1966
From:	Bernard H INSTITUTE FOR ATMOSPHERIC SCIENCES
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 9211190391
Download: ML20127J661 (3)

Text

.. _. -

i fDfL

-r /

~

===~~

. n,. =-

v

~~'

.-....n.,,

j:

UNITED STATES GOVERNMENT

~~-f

,n -

c..

Memorandum 7

yo - a. c o, i

To

Edson G. Case, Assistant Director DATE: October 26, 1956 Division of Reactor Licensing Eurold Bernard, Acting Chief rROM

// Environnental & Sanitary Engineering Br., RDT

$UbjECT: HAZARD 3 SW2/.!GU REPORT RDT:NS g+

i Reference is made to your letter of Au6ust 15, 1966, to the Environmental Science Services Administration requesting co:::ments on the following:

l Northern States Power Company Monticello Nuclear Generatin6 Plant, Unit 1 Facility Description and Safety-Analysis Report

{

Volume 1 and 2 dated August 8, 1966

'Ibe co:rrnts of the Environmental Meteorological Research Branch,- ARL, are attached.

J Attachments:

i Cc:::ments (orig. & 1 cy. )

\\

,*** 1

,~

c N

's N

W

\\

Q l

E. et I J

~

%fe;qh N l

J q

+

6 I

S l

er WL ButU.S. Savings Bondt Regularl) on tin Patroll Satings Plan L

9211190391 661026.

~

PDR ADOCK 05000263 A

PDR

.. [

h

~.

s-i I

Comments on i

Northern States Power Company Monticello Nuclear Generating Plant, Unit 1 Facility Description aid Safety Analysis Report i

Volume 1 and 2 dated August 8, 1966 j

1 Prepared by Environmental Meteorology Branch Institute for Atmospheric Tciences October 24, 1966 The Monticello site is located in the Northern Great Plains area which l

1s characterized by frequent storm center pv.ssages with dieir associated cloudiness and high winds, particularly from late fall to early spring.

4 The net result is a relatively low frequency of low level inversions amounting to about 30% of the total time over a year [13 and confined largely to the nighttime hours.

In the computation of dowawind surface concentrations and dosages of radioactivity the most sensitive parameter, besides the source strength emitted to the atmosphere, is the assumption of a 290 f t high release point. The maximum ground concentration from an elevated source will be higher during unstable conditions than during stable regimes since during periods of instability (rapid dif fusion rates) the stack effluent reaches the ground much closer to the stack location than is the case during stable conditions. As a consequence the controlling atmospheric condition at the nearest site boundary 1600 f eet to the south is one of rapid l

vertical dilution. This is evident from the relative concentrations shown in Table X111-4-4 of the report.

It is graphically shown in figure 7_ of Slade [2], where for a 260 f t stack height (to account for higher terrain at cite boundarv and a wind speed of 1 m/sec a maximum surface concentra-tion of 2.5x10-3)Ci/m i

3 per C1/sec results under type B (moderately unstable) dif fusion at the nearest site boundary. This compares well with the U-2 category shown in Table X111-4-4 Locally high concentrations can occur during f umigation -conditions, that is, at the time the nighttime surface inversion is destroyed. Assuming a mixing depth of 80 m, a wind speed of 1 m/sec and a cy value of 30 m, surface concentrations of 1.7x10-4 Ci/m3 per Ci/se'c released could occur at the nearest site boundary.

This value is an order of magnitude higher than the highest value in Table X111-4-4.- Consequently this condition could be a controlling situa-tion even though fumigationsof this type last on the average for periods of only about 1/2 hour.

?

~~

a-

. In the accident case of a radioactive superheated steam cloud issuing from the turbine building af ter portions of the roof and siding were blown out, the model used to predict the height of rise of the center-line of the cloud does not seem appropriate for the conditions being considered. Thereference(Singer,FrizzolaandSmith[3))citedin the report points out the empirical nature of the height of the plume centerline prediction equation, the meagerness of the data and the narrow range of observed centerline heights. A summary of their test data shows a maximan observed rise of 160 feet and a wind speed range of from 2 to 11 miles per hour. An extrapolation of a rise to 3780 feet and of a wind of 50 mph, as was done in the safety analysis, would seem a questionable procedure.

In summary, the general diffusion climate of the site is somewhat better (higher dilution rates) than the average condition in the United States.

However, because of the assumption of a 290 f t stack release, the controlling condition for off-site radioactive doses is one of rapid rather than poor dilution in the vertical.

References

[1]

Hosler, C. R., 1961 :

" Low-level Inversion Frequency in the Contiguous United States". Monthly Weather Review, Vol. 89, pp. 319-339.

[ 2] Slade, D. H., 1966: " Estimates of Dispersion f rom Pollutant Releases of a Few Seconds to 8 Hours Duration". ESSA Technical Not e 39-ARL-3, 26 pp.

[ 3]

Singer,1. A., Frizzola, J. A., and Smith, M. E., 1964: "The Prediction of the Rise of a Hot Cloud from Field Experiments".

APCA Journal, Vol.14, No, 11, pp. 455-458.

f

- _ _ _ _ _ _ _ _ _ _ _ _ _ _