PERTURBATION THEORY CONTROL ROD WORTH
This paper was presented to the American Nuclear Society meeting in Washington, D. C. on Dec. 11, 1956. A method is presented for the calculation of control rod worths by a combination of perturbation and transport theory. The perturbation theory finds the reactivity effect of absorber in the shape of the control rod. The transport theory calculates an effective absorption cross section for this absorber. One advantage of this scheme is that cruciform rods can easily be treated by transforming to a square reactor, in which case the rod boundaries are coordinate surfaces. Another advantage is that perturbation theory uses the simple diffusion solution in the unperturbed reactor where it is an excellent approximation; more rigorous methods can be used in the immediate vicinity of the rod surface. The use of perturbation theory restricts the method to rods which do not have an overwhelming worth, even though the flux dipping around the rod is accounted for in the calculation of an effective SIGMA /sub a/. A useful approximation for the DELTA k of a cruciform rod, good when the rod is thin and small compared to the reactor dimensions, and black to thermal neutrons, is given. A similar expression is derived for the case in which the rod absorbs resonance as well as thermal neutrons. (auth)
- Research Organization:
- Westinghouse Electric Corp. Atomic Power Dept., Pittsburgh
- NSA Number:
- NSA-12-004476
- OSTI ID:
- 4337696
- Report Number(s):
- WCAP-380
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ABSORPTION-- CONTROL ELEMENTS-- CROSS SECTIONS-- MATHEMATICS-- MECHANICAL STRUCTURES-- REACTORS-- RODS-- SURFACES-- TRANSPORT THEORY
PHYSICS