Calculational Methods

DOE-STD-1135-99

1.3 Neutron Absorbers

The individual should be able to:

a. Describe the use of neutron poisons.

b. Explain the absorption characteristics of the following elements in terms of their

cross-sections: cadmium, boron, chlorine, gadolinium, and hydrogen.

c. Explain the purpose and use of Raschig Rings as a neutron poison.

2.0 Calculational Methods

Various calculational methods are used depending on the complexity of the problem being

evaluated. This information can be obtained through various Monte Carlo classes, short

courses, or college classes. See Appendix A for available training resources.

The individual should be able to:

a. Identify and discuss the application of several common hand calculation methods.

b. Select one hand calculation technique (buckling method, solid angle, or areal density)

and prepare an example of its use.

c. Develop input model for one of the criticality safety codes (i.e., MONK, VIM,

KENO/SCALE, MCNP, DANTSYS, ANISN, COG).

d. Describe how cross section data impact Monte Carlo and deterministic codes.

e. Describe the importance of validation of computer codes and how it is accomplished.

f. Describe the methodology supporting Monte Carlo codes and deterministic codes.

g. Describe pitfalls of Monte Carlo calculations.

h. Discuss the strengths and weaknesses of Monte Carlo and Discrete Ordinants codes.

i. The diffusion theory model is not strictly valid for treating fissile systems in which

neutron absorption, voids, and/or material boundaries are present. In the context of

these limitations, identify a fissile system for which a diffusion theory solution would

be adequate.

3.0 Critical Experiments and Data

The purpose of this competency is to ensure that the individual has the familiarity

with critical and subcritical experiments and the use of the resulting data. The

individual shall be able to give examples of critical and subcritical experiments,

explain what the data from these experiments are used for, and describe the

parameters involved in a solution and metal criticality accident. This knowledge is

necessary to determine the applicability of experimental data to normal and abnormal

process conditions addressed by NCS Evaluations and to utilize existing kinetics

experiments and accident data that characterize the physics and consequences of

criticality. The individual should also be aware of situations where little or no

experimental data exists.

Hands-on training with critical experiments is covered in Section 9.0.