Reactor Theory (Nuclear Parameters)
DOE-HDBK-1019/2-93
CONTROL RODS
In this example the various approximations used did not cause any difference because the
problem deals with a section of the curve with an approximately constant slope. To
obtain the value over the interval between 8 inches and 20 inches, however, would require
the use of several subintervals (as in the last approximation) to obtain an accurate
answer.
Example 3:
For the differential rod worth data given below, construct differential and integral rod
worth curves.
Interval (inches)
Reactivity Inserted (pcm)
0 to 2
10
2 to 4
20
4 to 6
40
6 to 8
60
8 to 10
60
10 to 12
40
12 to 14
20
14 to 16
10
Solution:
Differential rod worth:
For each interval, the number of pcm/inch must be determined. For example, in
the first interval (0 inches to 2 inches), 10 pcm is added. Therefore, the
differential rod worth equals an average 5 pcm/inch. This value of differential
rod worth is plotted at the center of each interval. The center of the interval
0 inches to 2 inches is 1 inch. The values of pcm/inch for each interval are then
listed as shown below and plotted on Figure 12.
Interval Center
pcm/inch
1
5
3
10
5
20
7
30
9
30
11
20
13
10
15
5
Rev. 0
NP-03
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