PROBABILITY DISTRIBUTION OF NEUTRONS AND PRECURSORS IN A MULTIPLYING ASSEMBLY
The probability distribution of the number of neutrons and delayed neutron precursors in a multiplying assembly is considered. Particular emphasis is placed on the probability distribution for a system which is brought to a supercritical state in the presence of a neutron source which is so weak that deviations from the average population may be large. A space independent model is used with one group of neutrons. The problem is formulated in terms of the probability distribution generating function which satisfies a partial differential equation, which is derived. Its solution is attempted by the method of characteristics and general properties of the characteristic curves and the solution are discussed. The method is applied to a system without delayed neutrons, and, for a constant source, the generating function and probability distribution are found. The multiplication of precursors is treated in a short neutron lifetime model for a system which is below prompt critical. For a single group of precursors and constart reactivity, the generating function is derived. The short neutron life-time model is extended to a system above prompt critical, and again the generating function is found in a simple case. Calculation results are compared with experiments on Godiva and good qualitative agreement is shown. (auth)
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- NSA Number:
- NSA-17-017091
- OSTI ID:
- 4722159
- Report Number(s):
- LADC-5383
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- United States
- Language:
- English
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