OPTICAL ABSORPTION IN FUSED SILICA DURING TRIGA REACTOR PULSE IRRADIATION

摘要

An experimental investigation was conducted to determine the spectral trans¬mission characteristics of fused silica before, during and after exposure to reactor irradiation pulses. The transmission measurements were carried out at three wave¬lengths (0.215, 0.625 and 1.0 microns) and at a range of temperatures from ambient to 900°C Corning 7940 fused silica specimens in a corner cube configuration were mounted next to the reactor core face of the University of Illinois' TRIGA Mark II reactor. Peak neutron and gamma fluxes obtained from this reactor were approxi¬mately 5.4 x 1015 n/cm2 -sec and 6.1 x 107 R/sec, respectively. Neutron and gamma doses associated with these pulses were 2.3 x 1014 n/cm and 2.6 x 10° R, respec¬tively. The effective time of the pulse obtained by dividing the total dose by the peak flux was approximately 0.043 sec. The transmission measurements were made immediately before, during and after the reactor pulses to monitor both the cre¬ation of irradiation induced absorption and the decay of the induced absorption after the pulse.