Circuit Breakers With Different Icu/ics

Typically, сircuit breakers are offered in 2 or 3 short-circuit breaking capacity ratings. For example, 40kA, 70kA and 100kA at 400V

What design features makes them different? Is it bigger/smaller contacts or stronger/weaker springs or something else?..

Is it possible to build short-circuit proof softstarter ?

I want to configure short-circuit proof softstarter (protected by motor circuit breaker) from standard components offered by manufacturer.
I think this way:

1. Oversize the softstarter by 2 - 2.5 times, because manufacturers ratings are overly optimistic.

2. Place a 1.5% reactor upstream of softstarter. This reactor will limit current in case of short-circuit.

Is this idea good or wrong? Any comments are welcome.

detunig reactor and critically corrected motor

Is the detuning reactor can help limit possible current and voltage peaks on critically corrected motor? Capacitor connected directly to motor cable (static correction).