Irradiation and Testing at 4.5 K of Epoxy-Glass-Fibre-Steel Samples

A review of irradiation effects on organic-matrix insulation

“…The annealing was thus considered to activate latent damage from the '°Co-gamma irradiation, rather than to cause recovery. Since the shear modulus was similarly affected by annealing, while the Young's modulus was unchanged, Such an experiment was recently carried out at the Garching reactor by Katheder et al [1992]. Preliminary results indicated that warm-up improved …”

“…The 4-K irradiation was performed in the Garching FRM (ForschungsreaktorMiinchen),with about 20% of the dose from fast neutrons~and about 50% from gamma rays [Wanner et al, 1988;Gerstenberg and GIZiser,1992;Katheder et al, 1992;Munshi, 1992]. Both irradiation sources were fission reactors, so both neutron spectra were similar, although measurable differences in the fast neutron spectra have been reported .…”

“…The high energy portion of the neutron spectrum is shown in Figure 1.8. About 50% of the total dose is from gamma radiation [Katheder et al, 1992]. One of the resins tested was DGEBA, the second was EPN, and the third was a multifunctional epoxy similar to TGDM or TGPAP.…”

“…The fabrication process considered during the conceptual design activity for magnet turn-to-turn insulation was vacuum impregnation of fiberglass with a low viscosity epoxy resin. However, data on epoxy resin systems that may not be ideal for vacuum impregnation are also (1) Specimens wouldbe irradiated at 4 K in a neutron and gamma spectrum similar to that expected at the ITER magnet location at doses up to and somewhat above those allowed ( Radiation Exposure [Bottura et al, 1991] [Katheder et al, 1992]. A memo on ITER shield design [E1- Guebaly, 1990] gave a fast neutron fluence to the insulator of about a factor of 3 times the "peak" fluence of 2.4 x 10z/m2, and a memo from M. Sawan [1993] set forth a fast neutron fluence of 3.6 x 1022/m2with a harder spectrum for a recent design.…”

“…No measurable mass changes were found (<0.2 mg in specimens of mass 62 to 500 mg). The neat resin systems were tested in compression at 77 K without warm-up, except for one system that was warmed up after the highest dose of 1. resistance [Katheder et al, 1992].…”