Using the LTA

DOE-STD-1052-93

(3)

Does the failure cause a power reduction greater than 10 percent or result in a

forced outage?

NOTE:

The amount of power reduction or other operational impact should

be established by plant management.

This question divides the nonsafety-related failures into two groups, operational and

economic:

Yes - Those failures that directly impact operations and power generation. These

failures affect the ability of an operations-critical system to perform its primary

function.

No -

Those failures that impact support functions or result in a power reduction less

than 10 percent, or those failures with a purely economic impact.

(4)

Does the failure cause a plant scram?

This question divides failures that impact operations into two groups, scram initiator

and operational impact:

Yes - Those failures that result in a plant scram.

No -

Those failures that result in a forced outage, a power reduction less than 10

percent, or other operational impact.

8.1.1 Using the LTA, categorize each failure mode according to its consequence

and importance to the operation of the plant. The importance classes are

described below:

Class A (Safety) - Failure modes that affect personnel and/or reactor safety.

Scheduled maintenance is required and shall reduce the likelihood and severity

of the failure to an acceptable level; otherwise, the component/system should

be redesigned.

Class B (Scram initiators) - Failure modes that may cause plant scrams.

Scheduled maintenance or a design modification is required to reduce

operational costs and limit challenges to safety systems.

Class B2 (Operational Impact) - Failure modes that result in a forced outage,

power reductions less than 10 percent power, or other operational impact.

Scheduled maintenance or a design modification is necessary to reduce

operational and corrective maintenance cost.

D - 35