In each nomogram, the R1 scale is at the right.

This scale shows H+1 dose

rates.

The Rt scale is on the left.

This scale shows dose rates at times other

than H + 1.

In working with nomograms, care should be taken to be as consistent as

possible when joining values with the hairline.

Be sure the hairline

intersects the vertical line and the interpolated value (tick mark) as

closely as possible. It is possible to find any one value on the nomogram

if the other three are given, as illustrated in the example problems below.

The following problems are concerned with technique only and do not consider

the impact that these high dose rates might have on operations in the

contaminated area.

GIVEN:

Rt = 150 cGy/hr at H + 3 hours.

FIND:

R1.

SOLUTION:

Since

the

soil

type

is

not

known,

calculations will be performed on the Soil Type II index

scale (Figure 5-7).

Align the hairline with the 3-hour

tick mark on the Soil Type II index scale and the 150 cGyph

point on the Rt scale.

Read the dose rate as 190

cGyph

at

the

point

of

intersection with the R1 scale.

ANSWER:

190 cGy/hr.

GIVEN:

R1 = 300 cGyph.

FIND:

Rt at H + 7 hours when the soil composition approximates

Soil Type III.