Technical Specifications are a set of requirements for different items
needed to preserve our deterministic analysis.
In general, Technical Specifications are known as Tech Specs,
and are required by different regulatory bodies.
They have different items, including operability, safety limits,
limiting conditions for operation applicability,
or LCO applicability,
surveillance requirements, design features
and administrative controls.
Operability, that is the first part,
means that the system, or piece of equipment,
let say component, a train, or any other device,
it is capable of performing its specified safety function.
To do this, it is necessary that all the support equipment,
systems, or components are also capable of performing their support functions.
To guarantee operabilty, there are decision trees.,
as we can see here.
And they analyze different scenarios and expected response to each other.
Also, no compliance with tech spec operability could require
shutting down the reactor.
We also have safety limits that are essential
to keep the safety analysis hypothesis.
Let’s consider, for example, the reactor coolant pressure
as a variable which can be under fast changes.
And thus, it cannot be controlled manually by a human operator.
That is why there is a control system that keeps the variable
and the normal control in a normal band during normal operation.
If that systems fails, what happen is that pressure will rise,
and a set of alarms will be appearing
in order to warn the operators of the upset of the plant.
Also, if the operator is not able
or does not manage to control the pressure,
this will continue rising until the safety-relief valves
of the RCS open.
Or until a reactor trip happens.
As you can see here, the safety limit is when the reactor
should start the trip.
If the system would rise to that limit,
the Reactor Coolant System would not be damage.
But there would be some uncertainties
about other parts of the RCS, like its pressure cracking point.