TSR Use and Application Modifications for SACs

DOE-STD-1186-2004

estimate of the risk involved in exceeding the analyzed MAR for some time interval to support

LCO action times as well as associated surveillance frequencies. The surveillance frequencies

are established to ensure a reasonably confident expectation that MAR will not be exceeded.

This must be documented in the supporting BASIS statements. When it can be defended, use

of a MAR LCO has the advantage of allowing the facility an action completion time which, if met,

would preclude a TSR violation. There are also feasibility limits associated with the LCO

approach in addition to the need for estimating the potential size and duration of MAR

exceedances. An example of this would be a facility that needs to control MAR in a very large

number of locations because of the way that the accident analysis was performed. If, for

example, a facility analysis was performed on a glove box, room, wing, and facility wide basis

and each of these yielded its own MAR limit. For consideration purposes, assume that for a

large facility, there may be 200 glove boxes, 100 rooms, two wings, etc. In this example, each

location may require its own entry in the TSR LCO creating a very large number of entries (in

this case potentially more than 300 entries). This could make the TSR LCO unduly complex

and unwieldy from a human factors reliability perspective.

In the event that no reasonably confident estimate can be made of potential MAR exceedances

to support action times and surveillance frequencies, or if the LCO is too complex and unwieldy,

it may be hard to defend an LCO approach. In this case, it would be appropriate to use a TSR

Section 5 Specific AC. Because of the importance of controlling MAR to within the bounds of

the analyzed consequence and hazard analyses, and the need for unequivocal MAR limits in a

TSR, a directive action Specific AC is preferred. However, directive action SACs do not support

action times to allow the facility some time to correct the MAR exceedance. For the case

involving the use of SACs, directive language should be used in the form of a SHALL statement

which sets the maximum MAR limit. A violation of this Specific AC limit is an immediate TSR

violation in this case.

4.4

TSR Use and Application Modifications for SACs

In both cases, the Use and Application section of the TSR should define the ground rules for

treating SACs, including treatment of non-compliances as TSR violations and associated

reporting requirements. In addition, it is helpful to include a statement of the basis of the

Specific AC where it is invoked.