PREDICTION OF RADIONUCLIDE DEPOSITION
725
Table 1— WASHOUT FACTORS, W,, AND DRY-DEPOSITION
VELOCITIES, Vg, FOR FALLOUT RADIOACTIVITY FOR
DIFFERENT LOCATIONS AND DATES*
w,1?
-
Ves 2?
Time of W,
em,/sec
Time of V,
England
230 (87Cs)§
130 (Zr)§
560 (ICs)
520 (44Ce)
480 (149Ba)
500Zr)
420 (1317)
July 1958—June 1959
(yearly average)!
Sept.— Nov. 1960
0.07 (gross
beta)
1956-1957
(average)!
0.70 (gross
beta)
Sept. 1956—Sept. 195°
(average)?
(three-month average)®
Sept.—Nov. 1961
(three-month average)?
Norway
645— 6450
(gross beta)
516— 3220
(gross beta)
Sept. 1956—Sept. 1959
(range of monthly averages)?
Sept. 1955—Apr. 1957
Holland
(range of monthly averages)?
Germany
430
(gross beta)
July—Dec. 1957
(six-month average)?
United States (Tecumseh, Mich.)
475—2100
(gross beta)
Jan. 1963-June 1964
(range of four-week averages)
0.29 (gross
Sept. 1961—Jan. 1962
0.20 (gross
Feb. 1962—July 1962
Feb, 1963—June 1964
beta)
beta)
*Unless otherwise
concentrations.
Av. 1962—Jan,. 1963
(average)
(average)
specified, washout factors were computed using surface-air
~W, is the radioactivity concentration in rain in picocuries per kilogram dividec
by the radioactivity concentration in air in picocuries per kilogram,
iV, is the rate of deposition in picocuries per square centimeter per second divided by the concentration in air in picocuries per cubic centimeter.
§$Computed using air concentrations at 1200 m.
artificially generated; particle sizes were reported to be in the sub-
micron range. For purposes of this paper, we are concerned only with
the dry fallout onto precipitation collectors.
Table 1 also shows some measured deposition velocities of gross
beta radioactivity onto precipitation collectors. It appears that the dry-
deposition velocity can vary widely from place to place and from time
to time. The important thing to note here is that, despite these different deposition velocities, the total deposition of dry fallout onto the