Requirements - std1134990011

DOE-STD-1134-99

the system. Discrepancies in the annular thickness are potentially safety significant and must be

corrected whereas discrepancies in the height are immaterial and no further action is required.

Therefore, if a given system parameter can be extended to infinity or an infinite system and

criticality is not achieved, discrepancies in the model or report related to this parameter are not

safety significant.

One area where an overly detailed model can impact the analysis and operation adversely is in

the area of "infraction traps." If the description section is extremely detailed then there is a good

chance the associated limits and controls will be similarly prescriptive. Such unnecessary

"requirements" can overwhelm operations with trivial demands, damage the credibility of the

criticality safety program, and mask more serious noncompliance issues. The reviewer should be

aware of the potential to "over describe" the system and define controls which have no bearing

on the criticality safety of the operation. Consider the annular tank example again. Assume the

description section specifies the annular dimension as 1.500 +/- 0.125 inches. Then the

associated limit follows suit. Note that if the actual annular dimension is found to be either 1.3

inches or 1.7 inches, a criticality safety infraction ensues. For an isolated annular tank, the tank

will remain subcritical with an annular thickness up to just over 3 inches (assuming uranyl nitrate

solution concentrations not exceeding 400 g/l). There is no need to specify a minimum annular

tank thickness unless it is an Engineering Safety Requirement in Section 7. Hence, operations

will be unduly impacted by a criticality infraction that has no bearing on safety (i.e., "infraction

trap"). The reviewer should ensure that the descriptions of the system and associated models are

detailed enough to ensure that potential criticality scenarios are analyzed appropriately without

unnecessary specification. For example, if the tank deformation must be bounded, design

pressure and available pressure sources for the tank system must be discussed.

Key Review Issues

If not familiar with the fissile system/operation, conduct a walkdown of the facility.

Identify those items and parameters with safety significance.

Ensure there is enough detail to understand what was analyzed.

Compare the system description to calculational models (internal consistency) and to the "as

found" facility (external consistency).

Identify safety significant discrepancies.

Look for unnecessary specification of the system and "infraction traps."

Look for equipment used in the operation that has criticality safety significance.

3.0 Requirements

Any special requirements that impact the methodology of the analysis or drive special

documentation are specified in this section. References to predecessor criticality safety

evaluations relied upon to provide detailed documentation of the safety basis may be included.

There is no need to state requirements of "routine" orders (e.g., 5480.24) and standards (e.g.,

ANSI/ANS) either explicitly or by reference.