Radiation thresholds - ITER Electronics Radiation Hardness Assurance

The table below, excerpted from the ITER policy on electronics exposed to radiation, gives the radiation thresholds above which:

a radiation mitigation strategy and/or a radiation qualification strategy are mandatory for non-critical systems with electronics (rows 2) and without electronics (rows 4);
a radiation mitigation strategy is mandatory for critical systems with electronics (rows 1) and without electronics (rows 3);
a radiation mitigation strategy and/or a radiation qualification strategy is mandatory for critical systems without electronics (rows 3).

	Sub-system	Accumulated dose (Gray)	Neutron fluency (1 MeV SiO2 eq. n.cm-2)	Neutron flux (n.cm-2.s-1)
1	Critical system with electronics	1	10⁸	10
2	Non-critical system with electronics	10	10¹⁰	10²
3	Critical system without electronics	10³	N.A.	10⁴
4	Non-critical system without electronics	10⁴	N.A.	10⁵

Systems are considered as critical if they are classified Quality Class 1 or 2. This includes systems participating in nuclear safety functions, occupational safety functions, investment protection functions, and systems whose failure would result in a loss of plasma operation. Other systems are considered as non-critical.