That's part of the down side, though. There was a lot of explanation. Also, it surprised me that the dosimeter was a single point of failure for such a critical part of the ship. Since the techs had personal measures it's not a rare technology. To get the same effect maybe a rogue energy wave through space his the ship or something?
So in 2300AD there's something called a gravistatic charge that limits the Stutterwarps to a maximum of 7.7ly in any given direction. I realize now that that dosimeter isn't mentioned as different from the dosimeters for actual radiation.
Basically what was happening down there was twofold - one, the gravistatic charge was reaching maximum levels (a combination of Captain Rastmussen's inexperience with gravistatic charges, being a primarily in-system Captain who rarely had to discharge his old lugs, and a charge-meter that was left unmaintained or damaged in an unexpected way.) and two, the results of a gravistatic overload.
When the stutterwarp overloads, the radioactive element that allows Stutterwarp (Tantalum-180m) decays into Hafnium, essentially releasing a shitload of very lethal radiation. That's what appears on Remi's personal dosimeter, blows up the engine room, and what kills the whole crew.
In terms of replacing it with something else, I feel it detracts from my overall plan for the story - Remi's hardly the first psionic, merely the first human one. The intent is that a gravistatic decay and crew death can sometimes result in a psion - Humans just screw up far less than some species.
It would be unlikely for SEALs to be on a missile carrier as a standard practice. Marines, yes. SEALS tend to be more specialized and move around a lot.!
Mid-Tier SOF like SEAL Teams and Green Beret ODAs are actually the most common shipboard forces on patrolling cruisers. Marines deploy primarily aboard LC-20 landers, close escorts, and big assault ships, where they're better served as flag-showers, guards for customs boarding parties, and heavy assault troops.
Aboard a Kennedy, which has the fastest stutterwarp in human space outside of a French fast courier or Voir sensor drone, you typically want to deploy a group capable of direct action and reconnaissance, which you find in the hands of SEALs.
In this case, a full platoon is deploying to help recon Aurore after the French lost a decisive battle in orbit.