An Overview of the Risk Posed by Thermal Neutrons to the Reliability of Computing Devices

The high performance, high efficiency, and low cost of Commercial Off-The-Shelf (COTS) devices make them attractive also for applications with strict reliability constraints. Today, COTS devices are adopted in HPC and safety-critical applications such as autonomous driving. Unfortunately, we cannot assume that COTS chips manufacturing process does not include the cheap natural Boron, that could makes them highly susceptible to thermal (low energy) neutrons. Through radiation beam experiments, using high-energy and low-energy neutrons, it has been shown that thermal neutrons are a significant threat to COTS device reliability. The evaluation includes AMD APU, three different NVIDIA GPUs, an Intel accelerator, and an FPGA executing a relevant set of algorithms. Besides the sensitivity of the devices to thermal neutrons it is also fundamental to consider the thermal neutron flux in different scenarios such as weather, concrete walls and floors, or even HPC liquid cooling systems. Correlating beam experiments and neutron detector data, it is shown that thermal neutrons FIT rate could be comparable or even higher than the high energy neutron FIT rate.