IEC 60793-1-54-2018 pdf free.Optical fibres – Part 1-54: Measurement methods and test procedures – Gamma irradiation.
The attenuation of cabled and uncabled optical fibres generally increases when exposed togamma radiation.This is primarily due to the trapping of radiolytic electrons and holes atdefect sites in the glass (i.e. the formation of “colour centres”).This test procedure focuses ontwo regimes of interest: the low dose rate regime suitable for estimating the effect ofenvironmental background radiation, and the high dose rate regime suitable for estimating theeffect of adverse nuclear environments. The testing of the effects of environmentalbackground radiation is achieved with an attenuation measurement approach similar toIEc 60793-1-40 method A, cut-back.The effects of adverse nuclear environments are testedby monitoring the power before，during and after exposure of the test sample to gammaradiation. The depopulation of colour centres by light (photo bleaching) or by heat causesrecovery (lessening of radiation induced attenuation).Recovery can occur over a wide rangeof time which depends on the irradiation time and annealing temperature.This complicatesthe characterization of radiation induced attenuation since the attenuation depends on manyvariables 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. lfdegradation of cable materials exposed to irradiation is studied,other test methods will beused.
This test method is written to contain a clear,concise listing of instructions. The backgroundknowledge that is necessary to perform correct,relevant and expressive irradiation tests aswell as to limit measurement uncertainty is presented separately in lEC TR 62283.
2Normative references
The following documents are referred to in the text in such a way that some or all of theircontent constitutes requirements of this document. For dated references,only the editioncited applies.For undated references, the latest edition of the referenced document (includingany amendments) applies.
IEC 60793-1-40，Optical Fibres – Part 1-40: Measurement methods and test procedures -Attenuation
IEC 60793-1-44，Optical fibres – Part 1-44: Measurement methods and test procedures -Cut-off wavelength
3Terms and definitions
No terms and definitions are listed in this document.
ISO and lEC maintain terminological databases for use in standardization at the followingaddresses:
IEC Electropedia: available at http://www.electropedia.org/
ISO Online browsing platform: available at http://www.iso.orgl/obp
4.1General
Attention is drawn to the fact that strict regulations and suitable protective facilities are to beadopted in the laboratory for this test.Carefully selected trained personnel shall be used toperform this test. It can be extremely hazardous to test personnel if it is improperly performedor without qualified conditions.
4.2Radiation source
4.2.1 Testing of environmental background radiation
60Co or equivalent ionising source shall be used to deliver gamma radiation. Thisenvironment is characterised by relatively low total dose and dose rate.
4.2.2Testing of adverse nuclear environments
60co or equivalent ionizing source(s) shall be used to deliver gamma radiation. Thisenvironment is characterised by higher total dose and dose rate.IEC 60793-1-54 pdf download.