1. 1 SUMMARY OF PERFORMANCE ‘

Two prototype full-range instrumentation systems have been developed, each capable of covering about 10 decades of reactor power. ■ • ‘

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The in-core system contains two detectors. The first of these is a U — lined fission

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counter that covers the range 10 nv to 1.5 x 10 nv; at 10 nv the counting rate is 1. 5 cps, and 9 7

at 1. 5 x 10 nv (and 2.5×10 R/h) the counting loss due to the electronic subsystem is 23 percent. 235

The second is a U — lined fission chamber, operating in the MSV mode, that covers the range

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2.2 x 10 nv to 5 x 10 nv; at 2.2 x 10 nv the neutron-produced signal equals that produced by 2.5 x 10 R/h of gammas, and at 5 x 10 J nv the signal is still proportional to flux (indicating that even higher fluxes could be measured).

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The out-of-core system contains one detector, a U — lined fission counter-chamber. In

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the counting mode, this chamber covers the range 1.4 nv to 1.4 x 10° nv; at 1. 4 nv, the counting

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rate is 1. 0 cps, and at 1. 4 x 10 nv the counting loss due to. the electronics subsystem is 23 percent.

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In the MSV mode, this chamber covers the range 10 nv to 10 • nv; the lower limit may be some — ■

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what greater than 10 nv, depending on the gamma field in the vicinity of the detector, and the higher limit may be greater than 10^ nv for the signal is still proportional to flux at that level.