BS EN 60793-1-54:2018 outlines a method for measuring the steady state response of optical fibres
and optical cables exposed to gamma radiation. It can be employed to determine the level of
radiation-induced attenuation produced in Class B single-mode or Class A, category A1 and
A2 multimode optical fibres, in either cabled or uncabled form, due to exposure to gamma
radiation.
The attenuation of cabled and uncabled optical fibres generally increases when exposed to
gamma radiation. This is primarily due to the trapping of radiolytic electrons and holes at
defect sites in the glass (i.e. the formation of "colour centres"). This test procedure focuses on
two regimes of interest: the low dose rate regime suitable for estimating the effect of
environmental background radiation, and the high dose rate regime suitable for estimating the
effect of adverse nuclear environments. The testing of the effects of environmental
background radiation is achieved with an attenuation measurement approach similar to
IEC 60793-1-40 method A, cut-back. The effects of adverse nuclear environments are tested
by monitoring the power before, during and after exposure of the test sample to gamma
radiation. The depopulation of colour centres by light (photo bleaching) or by heat causes
recovery (lessening of radiation induced attenuation). Recovery can occur over a wide range
of time which depends on the irradiation time and annealing temperature. This complicates
the characterization of radiation induced attenuation since the attenuation depends on many
variables including the temperature of the test environment, the configuration of the sample,
the total dose and the dose rate applied to the sample and the light level used to measure it.
This test is not a material test for the non-optical material components of a fibre optic cable. If
degradation of cable materials exposed to irradiation is studied, other test methods will be
used.
All current amendments available at time of purchase are included with the purchase of this document. | ISBN(s) : | 9780539026603 |
| Number of Pages : | 20 |
| Published : | 10/31/2018 |
