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DEFENCE IN DEPTH
Defence in depth: sources

FOR EVENTS INVOLVING FISSILE MATERIAL

 

For events involving fissile material, the Manual gives some more specific guidance.

Events involving fissile material

Events related to criticality safety

The general approach that was used for categorizing sources did not specifically address the possibility of criticality accidents.

As such accidents could lead to consequences rated at Level 5 on INES, events related to criticality safety should consider the material as a Category 1 source.

Events NOT related to criticality safety

For events involving fuel, but not related to criticality safety, the appropriate category should be used. 

Unirradiated fuel

For unirradiated fuel, this can be calculated from the D values given in Table 22 of Appendix III. 

Irradiated fuel

For irradiated fuel, there are obviously many isotopes involved and the simplest approach is to assume Category 1.

However, for very small quantities of fuel (e.g. in a laboratory) this may be inappropriate and then a specific calculation can be carried out.

TABLE 22. D VALUES FOR A RANGE OF ISOTOPES

Radionuclide

D(TBq)

Am-241

6.E-02

Am-241/Be

6.E-02

Au-198

2.E-01

Cd-109

2.E+01

Cf-252

2.E-02

Cm-244

5.E-02

Co-57

7.E-01

Co-60

3.E-02

Cs-137

1.E-01

Fe-55

8.E+02

Gd-153

1.E+00

Ge-68

7.E-01

H-3

2.E+03

I-125

2.E-01

I-131

2.E-01

Ir-192

8.E-02

Kr-85

3.E+01

Mo-99

3.E-01

Ni-63

6.E+01

P-32

1.E+01

Pd-103

9.E+01

Pm-147

4.E+01

Po-210

6.E-02

Pu-238

6.E-02

Pu-239/Be

6.E-02