High Quality Content by WIKIPEDIA articles! Hardened Core, or H-Core, is a patented is a technique for the detection and correction of radiation-induced single event upsets that propagate into the internal control circuits. This type of upset is known as a single event functional interrupt (SEFI). H-Core employs an radiation hardened circuit connected to the system microprocessor. H-Core, combined with other radiation mitigation techniques such as TTMR, can be used to create a space-qualified fault-tolerant computer.