The Limiting Conditions for Operation, or LCO, ensures
that the safety analysis hypotheses related to the operability of equipment
and the control of slowly changing variables,
process variables are valid
during the operation of the power facility.
When an LCO applies to equipment,
in that case, they are defined by the NRC
as "the lowest functional capability, or performance level,
of equipment required for safe operation of the facility."
But also, LCOs can apply to some features
or technical conditions.
In that case they define values within which the reactor must operate
in order to mitigate the consequence of a possible transient or accident.
Also, in the Tech Specs, we have the Surveillance Requirements.
The monitoring requirements that are vital to periodically check
some of the functional requirements of the systems
or the adequate value of some variables.
The monitoring requirements do not ensure the operability of the equipment.
For example, a monitoring requirement measures the flow,
but not if the wall thickness of the pipe is adequate,
nor does it show whether the system is capable
of performing its function during an earthquake
or after an earthquake.
The essential message here is that a mere formal compliance
with Tech Specs does not guarantee the safety of the installation.
In fact, fulfilling all the Tech Specs can put the plant
in a situation of high risk.
The Tec Spec were not designed to enter them voluntarily,
but for random situations of component failures.
That is why Risk Monitors have been implemented
that provide an additional vision.
That is also why some plants, such as South Texas Project,
have implemented risk-informed Tec Specs
that take into account the interactions between variables and components.