iter structural design criteria for in-vessel components (sdc-ic)

ITER G 74 MA 8 01-05-28 W0.2
with an elastic follow-up factor r as defined in IC 2724. Note that when the uniform
elongation of the material drops below 2%, r1 is set equal to infinity, which effectively
implies that the secondary stresses are considered as primary.
If swelling is not negligible (B 3022), then swelling-induced stresses (B 3024.1.1.1) have to
be included with the secondary stresses.
In determining the allowable stress Se, both Su,min and eu have to be evaluated at the same
thickness-averaged fluence and temperature.
In general, this rule does not become controlling until the material has lost significant
uniform elongation due to irradiation. Up until then, this rule need not be satisfied, as
indicated by the entry "no limit" in Table A.MAT.5.3.
Note: The value of r1 for Eq. (1) has been chosen conservatively to be equal to 4 (IC 2724).
In some cases r1 may be shown to be much less than 4. The designer may choose to reduce
the conservativeness by using a smaller value of r1 if it can be justified using the procedure
given in B 3024.2.
B 3212.2 Elasto-plastic analysis (Immediate plastic flow localization)
If irradiation-induced swelling is not negligible (B 3022), then swelling together with
irradiation-induced creep have to be included in the stress analysis using either the simplified
inelastic method (B 3024.1.1.1 and B 3024.2) or elasto-visco-plastic analysis (B 3024.4).
However, the strain limits of IC 3212.2 should be applied to the plastic strain, excluding the
irradiation-induced creep strain components.
B 3213 Immediate local fracture due to exhaustion of ductility
B 3213.1 Elastic analysis (Immediate local fracture due to exhaustion
of ductility)
Equation (1) of IC 3213.1 has been provided to guard against cracking in regions of stress
concentration including peak stress effects while Eq. (2) is for guarding against cracking
excluding peak stress effects, e.g., cracking of extreme fibers in bending due to exhaustion of
ductility by irradiation. The allowable stresses Sd (T, ft, r2) and Sd (T, ft, r3) for the two
cases are given in A.MAT.5.4 of appendix A. The value of the elastic follow-up factor r2 has
been set on the basis of analysis of notched tensile tests (Appendix C 3024.1.4) and on the
assumption that KT = 4. The value of r3 has been chosen conservatively on the basis of
analysis of three-point bend tests (Appendix C 3024.1.4). As before, the designer may
choose to reduce the conservativeness by using a smaller value of r2 or r3 if it can be justified
using the procedure given in B 3024.2.
If swelling is not negligible (B 3022), then swelling-induced stresses (B 3024.1.1.1) have to
be included with the secondary stresses.
Note 1: For materials like 316L(N) stainless steel, the true strain at rupture remains high at
temperatures £ 400¡C and does not reduce significantly up to a fluence of 10 dpa. For these
materials, the PL+Pb+Q+F limit need not be checked because, cracking at notch roots due to
SDC-IC, Appendix B. Guidelines for Analysis page 40