BS 7816-2:1997

Committees responsible
National foreword
Introduction
1 General
2 Power law extrapolation method
3 Superposition of time dependent data
4 Superposition of DED data
5 Conclusions
Annex
A (informative) Bibliography
Figures
1 Schematic illustrating the types of dose rate effects
    which can occur in radiation-aged polymeric materials
2 Interpolation of the end-point dose - Schematic
3 Extrapolation of end-point dose to lower dose rates -
    Schematic
4a Limitations - Extrapolation of DED near thermal ageing
    limit
4b Limitations - Extrapolation of DED in a polymer with
    type III behaviour
5 Elongation at break of polypropylene irradiated in
    air (from [7])
6 Extrapolation of end-point dose from data in figure 5
7 Extrapolation of end-point dose from XLPE (from [7])
8 Example where extrapolation of end-point dose is not
    feasible
9 Schematic - Superposition principle for thermal ageing
    and combined thermal-radiation ageing
10a Determining shift factors b(T) for thermal ageing
10b Superposition of data to yield master curve
11 Determination of activation energy E
12 Determination of shift factors a(T,D) for combined
    thermal-radiation ageing
13 Fitting experimental values of a(T,D) to the empirical
    model-equation (3)
14 Calculated DED using equation (3)
15 Experimental data for EPDM elastomer fitted to the
    superposition model
16 Calculated DED for 50% compression set
17 Calculated DED for 50% compression set
18 Calculated DED for e/eo = 0,5
19 DED values under combined thermal-radiation conditions -
    Schematic
20 Superposition of DED data - Schematic
21 Superposition of DED for Hypalon cable jacket material -
    (O - heterogeneous oxidation, - homogeneous oxidation
22 Superposition of DED for Hypalon cable jacket material -
    Homogeneous oxidation data only
23 Superposition of DED data for PVC showing type III
    behaviour - Homogeneous oxidation data only

Three methods which have been used to extrapolate data obtained from high dose rate experiments to low dose rates typical of service conditions.