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Classification of Sealed Radionuclide Sources

ISO classification (durability classes) In accordance with the classification system of sealed radionuclide sources based on GOST R 52241-2004 (International Standard ISO 2919-1999) each type of the produced sources is tested and test results are expressed as a five figure code preceded by the letter C or E. C indicates that the activity level of the sealed source does not exceed the maximum limit depending upon the toxicity of the radionuclide being used (under ISO 2919-1999). E indicates that the limit is exceeded.
A five figure code indicates the numbers of classes of durability to temperature, external pressure, impact, vibrations, puncture in accordance with the order stated in Table 1. A durability class of a sealed source of a certain type is determined by testing sources imitators or prototypes for conformity with standards of effecting factors of all types in accordance with Table 1. A sealed source is considered to have passed the test if it remains airtight after each performed test. Control of airtightness is performed under GOST R 51919-2002 (International Standard ISO 9978-92). In accordance with the set tasks using the data of Table 1, the customer can select the type of sources from the offered range. The list of more frequent fields of applications of sealed sources and their required minimal durability classes are given in Table 2.

Table 1

Effecting factor Durability classes in accordance with test requirements
  1 2 3 4 5 6
Temperature no test - 40˚ (20 min) - 40˚ (20 min) - 40˚ (20 min) - 40˚ (20 min) - 40˚ (20 min)
+80˚ (1 h) +180˚ (1 h) +400˚ (1 h) +600˚ (1 h) +800˚ (1 h)
    thermal shock to 20˚ thermal shock to 20˚ thermal shock to 20˚
External pressure no test 25 kPa absolute 25 kPa absolute 25 kPa absolute 25 kPa absolute 25 kPa absolute
to atmospheric 2 MPa absolute 7 MPa absolute 70 MPa absolute 170 MPa absolute
Impact no test 50 g from 1 m or 1)  1) 200 . g from 1 m or 1) 2 kg from 1 m or 1) 5 kg from 1 m or 1) 20 kg from 1 m or 1)
Vibrations no test 3 cycles, 10 min each 25 - 500 Hz at 49 m/ 2 (5 gg2) 3 cycles, 10 min each 25 - 50 Hz at 49 m/ 2 (5 gg2) 3 cycles, 30 min each 25 - 80 Hz at 1,5 mm amplitude peak to peak not applicable not applicable
  50 - 92 Hz at 0,635 mm amplitude peak to peak 80 - 2000 Hz at 196 m/2 (20 gn2)
  90 - 500 Hz at 98 m/2 (10 gn2)  
Puncture no test 1 g from 1 m or  1) 10 g from 1 m or 1) 50 g from 1 m or 1) 300 g from 1 m or 1) 1 kg from 1 m or 1)
1)equivalent delivered energy
2)maximum amplitude of acceleration

Table 2

Sealed source application Sealed source test and class
Temperature External pressure Impact Vibration Puncture
Industrial radiography sealed source 4 3 5 1 5
source in device 4 3 3 1 3
Medicine radiography 3 2 3 1 2
gamma teletherapy 5 3 5 2 4
brachytherapy 1) 5 3 2 1 1
surface applicators  2) 4 3 3 1 2
Gamma gauges (medium and high energy) unprotected source 4 3 3 3 3
source in device 4 3 2 3 2
Gauges with beta sources and low energy gamma sources for fluorescence analysis 2)2) 3 3 2 2 2
Survey of oil wells 5 6 5 2 2
Ion generators  3) chromatographs 3 2 2 1 1
electric neutralizers 2 2 2 2 2
smoke announcers  2) 3 2 2 2 2
Check source with activity of >1 MBq 2 2 2 1 2
Gamma-apparatus with dry storage of the source  2) 4 3 3 2 3
with wet storage of the source  3) 5 3 4 2 4
1)Sources of this type may be subjected to considerable deformation while exploiting. Manufacturers and users can provide special tests for them.
2)Excluding gas-filled sources. .
3)Assembly of the source and source in device may be tested.