Comment Re: If a motor is required to hold up the rods (Score 1) 168
Second, assume that you haven't thought up some new and novel failure scenario in the 30 minutes you've been thinking about it today than the engineers who have been designing and simulating for _years_.
These SMRs are specifically designed so that when things go wrong they fail safe, the reaction stops, no meltdown.
1) It is a conceit to believe all the edge cases have been considered.
2) There is also the "It is difficult to get a man to understand something when his salary depends on his not understanding it" factor.
"No engineer is going to intentionally-" "Morton Thiokol. Fukushima. 737-Max."
"The NuScale reactor has 1/20 of the nuclear fuel of a large scale reactor. Its small decay heat, inherent stability, and reactor physics eliminates fuel damage in all design basis events including those with failure of all control rods to insert. For beyond design basis events, radiation from fuel damage is below safe limits at the plant site boundary." The reactor can't fail in the same way the reactor at Fukushima Daiichi did. In the accident in Japan, the earthquake caused that reactor to successfully shut down. However the Tsunami cut off site power and swept away the backup diesel generators (backup onsite power). There was not sufficient batter power available to cool the reactor decay heat long enough for power to be restored. They did not have backup offsite generators near enough to fly in as is now required. If they had not suffered station black out the reactor would have been cooled long enough to go to cold shutdown. The SMR design is significantly smaller in size and power density, This means that if the reactor is shutdown but loses power cooling pump, the small size of the core reduces the total heat load and even with loss of offsite power the decay heat can be removed. If the reactor fails to shut down (partial or fully stuck control rods) the core inventory is small enough that any radioactive release would fall below regulatory limits at the site boundary.