The various alternatives offered by the development instrumentation system are illustrated

in Figure 1-1. On the left, an application using an in-core detector (ion-chamber) would use the

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counting channel to monitor from 10 to 10 of rated PERCENT POWER, and by successive partial withdrawal movements of the detector could continue to monitor well into the intermediate

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range. The in-core Campbell system would overlap the counting channel at approximately 10 of rated PERCENT POWER, and provide coverage into the power range without withdrawal of the detector. Each counting and Campbelling channel has an associated mechanical drive subsystem to position each detector at any desired point between the initial in-core elevation and the storage elevation beneath the core. •

On the other hand, those applications not requiring the use of in-core detectors may attain. similar performance using larger out-of-core detectors, as shown on the right in Figure 1-1

The counting channel would function from 10 ^ to 10 ^ of rated PERCENT POWER, and the Campbell channel would overlap and continue coverage through full-rated output of the plant. These detectors remain in a fixed position at all times. ‘ .

Thus, the development instrumentation system offers the following significant advantages relative to conventional instrumentation: .

a. The power plant designer may choose between in-core and out-of-core detectors for

. his application, and yet retain a consistent electronics system.

b. Only two channels of electronics are required to monitor from source level through

.. rated plant output power. . . •

c. The Campbell system provides for. improved discrimination against gamma flux, and

■ enables monitoring under certain conditions where conventional instrumentation would be inoperable.