Category Archives: Handbook Nuclear Terms

“Out-of-Core” Defined

Figure 2 1 shows a typical location for an out of core neutron sensor In this example, the sensor is also outside the reactor vessel The figure also shows the magnitude of the neutron flux, the gamma exposure rate, and the temperature in the out of core location typical of a boiling-water or pressurized-water reactor during operation at rated power

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Self-Powered Neutron Detectors

The problems of manufacturing in core fission cham bers and ion chambers small enough to fit the allowable space, rugged enough to withstand the in core environment, and inexpensive enough to permit extensive coverage of a power reactor core have led to efforts to develop other types of devices to measure neutron flux at fixed locations in a power reactor […]

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Statistical Accuracies

Formulas for computing the expected variation due to the statistical nature of an experiment are vital in optimum planning. Table 6.16 contains formulas useful in ascertain­ing the precision of the various functions involved in noise analysis. The meaning of the fractional-error formulas is that, if many values of a function were determined (at a particular f or t), 68 3% […]

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Preface

Nuclear power technology has reached the stage where there are “accepted practices” m many aspects of reactor design and construction The systems of instrumentation used in reactors of a specific type have more common features than differences Changes are gradual and evolu­tionary What is accepted practice today will be recognized as good practice for some years to come This does […]

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Installation

An in-line sensor or a tap to an adjacent mounted sensor must be located in a position where errors due to local disturbances, such as turbulence and vibration created by the process or adjacent machinery, are avoided For accuracy in lower pressure ranges, the sensor should include provisions for compensating for the weight of liquid in connecting lines so that […]

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Reactivity

When a nuclear power-reactor plant is generating electrical energv at a steadv or constant rate, the reactor is in a steady state m which the neutron density is fixed, the temperatures at various positions in the reactor are con­stant, etc Equations 1 7 and 1 8 show that, since dn/dt = dC,/dt = 0 in this steady state, the effective […]

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Neutron Sensors — In-Core

Howard H Stevens 3- 1 INTRODUCTION In core neutron sensors accomplish one or more of the following (1) confirm calculated core performance (2) confirm core operating safety margins, (3) provide input data for fuel management and (4) detect the existence of xenon induced power asymmetries or oscillations (see Chap 1, Sec 1 — 3 6(a) for a discussion of xenon)

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