Coupling Parameters for Partially Reflected Reactors

Conference · Sun Nov 12 04:00:00 EST 1995

OSTI ID:102189

Busch, Robert D. ^[1]; Spriggs, Gregory D. ^[2]

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1. University of New Mexico, Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering
2. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

For situations in which the standard point kinetic model does not adequately characterize the kinetic behavior of a reflected system, the Avery-Cohn differential equations can be used. However, these equations require that one determine the coupling parameters between the core and the reflector, f_cr and f_rc. The coupling parameter, f_crrc, represents the probability that a neutron in the reflector will scatter back into the core. As discussed in Reference 3, these two coupling parameters can be calculated from the multiplication factor of the bare core, k_c, the effective multiplication factor of the integral system, k_eff, and the fraction of system neutrons absorbed in the core region, P_ca. The methodology presented in Ref. 3 was described for a fully reflected system, but it is also applicable to some types of partially reflected systems. In particular, it is applicable to those systems where neutrons leaving any core surface not contiguous to the reflector have a zero probability of entering the reflector. In other words, these surfaces have a view factor of 0 to all reflector surfaces in the system. However, if the view factor between an unreflected core surface and a reflector surface is not zero, then the aforementioned methodology has to be modified. To calculate f_cr, one must include an estimate of the single-pass probability that a neutron escapes from the core to infinity, f_ci. This is accomplished by including a view factor(s) in the calculations that accounts for the fraction of neutrons that are not traveling on a line intersecting some portion of the reflector. This paper illustrates this modification by assuming the partially reflected system shown in Fig. 1c.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); University of New Mexico, Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 102189
• Report Number(s): LA-UR--95-2028; CONF-951135--15; ON: DE95015291
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
42 ENGINEERING
CALCULATION METHODS
MODIFICATIONS
MULTIPLICATION FACTORS
Modifications
NEUTRON REFLECTORS
NEUTRON TRANSPORT THEORY
Nuclear Criticality Safety Program (NCSP)
PROBABILISTIC ESTIMATION
Partially Reflected System
REACTOR CORES
REACTOR KINETICS
REACTOR KINETICS EQUATIONS
REACTORS