j=
Reduce the average concentration of the "defined
Iwoinm
2.
region’ te some lower number which shall be determined by cost-benefit
(4} Condition D:
i
comsicerations, but will usually not be belowlocal background.
An assay area whose average Pu concentration
is exy 5 ca thickness of soil below the suriace layer wiici measured(at& the
to exceed 400 pCi/g will be
wt 67 vercent ccorfidence level)
excavated
Bete and measured iteratively until
its averare Pu concentration
»
in the new 5 cm lever is found by measurement (at the 50 percent conficence level) to be reduced in the defined region to some lower number
Which shall be cetertined by cost - benefit considerations, but wil]
ust2ily not be below Jocal background.
Footnotes:
1
L
Assay Area.
=:
.
The field of view of the in situ detector in its
normal operating position; typically a 28 meter diameter circle of
53 - 5 cm in depth.
Scattered measurement can be used to estimate average
presven known as ‘'hrigzing.
5
at
— Stetisticaliy, t¥o-thirds
of the time the actual concentration will
he below the guide
rougher.
TS
fllDe
One-third of the time the actual concentration
may exceed the mother by some percentage.which must be empirically deter-
mined fp to 20-59 percent, as an estimate).
This is similar to using a
lower.
If a 90 percent confidence level were used with the numerical
guide, the equivalent guide at a 50 percent confidence level would
C-2-E-7
fro
$9 percent conficence level with a numerical guide 20-30 percent (estimated)
[Nh
oo
belew ‘2 rCi/g.