Safety Analysis and Control

DOE-STD-1135-99

consult with operations personnel and should be familiar with other programs that

directly relate to criticality safety such as human factors, fire safety, safeguards, and

The training process for this competency is most effective when completed at the

Engineer's facility with the aid of a qualified NCS Engineer.

The individual should be able to:

a. Develop contingency analysis, limits and controls.

b. Describe key personnel needed to assist in preparation of criticality safety

evaluations and determination of process upsets.

c. Describe how subcritical margins and limits are determined.

d. Describe when validation and bias estimates must be considered.

e. Describe typical criteria to consider when evaluating various fissile processes,

including common process upsets: Aqueous, Metal, Recovery,

Fabrication/Foundry, Mixed Waste.

f. Describe criteria to consider for evaluating material storage: Pits, Waste, Fuel

elements, Solutions, Metal parts.

g. Discuss the industry reference material used in determination of critical mass: LA-

10860, LA 12808, and TID 7016.

h. Describe elements to consider when preparing a Safety Analysis Report for

Packaging (SARP).

i. Discuss the effects and applications of the following factors relevant to criticality

safety of operations: Mass, Interaction, Geometry, Moderation, Reflection,

Concentration, Volume, Neutron absorbers, and Enrichment.

j. Discuss the influence of the presence of non-fissionable materials mixed with, or in

contact with, fissionable material on nuclear criticality safety.

k. Discuss the concept of contingencies for checking the validity of criticality safety

limits and controls.

l. Discuss the methods used in the calculation of criticality safety, source term,

environmental transport, and dose assessment activities including commonly used

computer models.

m. Demonstrate familiarity with the published histories of criticality accidents with

emphasis on the control failures, terminating mechanisms, and resulting radiation

hazards/health consequences to nearby personnel.

6.0 Safety Analysis and Control

When significant quantities of fissile material are handled or stored in a facility, the

criticality safety program is an integral part of the facility safety authorization basis.

Facility safety analyses typically contain information to demonstrate compliance with

applicable requirements for the prevention of inadvertent criticality and mitigation of

consequences from a criticality accident. The analyses of natural phenomenon events

create a common interface between NCS and the SAR. In addition, the analyses

typically contain information assessing the risk for postulated criticality accidents

providing the bases for Unreviewed Safety Question Determinations (USQDs).