Reply to thread

A typical nuclear EMP has a peak electric field strength of 50 kV/m

Lead foil wrapped Sn plated brass cases for RF circuits can effectively attenuate RF (not Gamma) but the I/O cables need special protection like "ESD -proof on steroids."

Any gaps can be penetrated in lids unless they are tight but the I/O cables are the vulnerable conductors all around for Gamma Radiation from a major solar flare (1 per century ? ) or a nearby nuclear explosion.  The energy of the gamma rays (typically 0.1 to 10 MeV for nuclear events).

Your assumptions might be invalid if discrete H/W can be modified much easier than a fuselink PROM in an MPU.  Although analog won't latch-up, it may melt.

 AT89C51RD2 (an 8-bit microcontroller), has shown that they can operate up to a total absorbed dose of about 0.6 kGy (600 Gy) of gamma radiation without significant degradation.

A 3 cm thick lead shield provides a good balance of protection and practicality, reducing the dose well below the failure threshold for most gamma ray energies encountered in a nuclear event.