Volatile memories, DRAM and SRAM, use a capacitor to store charge or a simple latch to store state. These cells can be upset by alpha particles, cosmic rays, heavy ions, gamma, x-rays, etc. which cause bits to flip to an opposite state to cause a soft error. Since the F-RAM cell stores the state as a PZT film(lead zirconate titanate ) polarization, a particle hit is very unlikely to cause the polarization to change a given cell’s state. You can also refer to attached document for some numbers.
Radiation.pdf 474.4 K