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Cobalt 57

Gamma Half Life
0.1221 MeV 271.74 days

In Use

The following quantities will give a dose rate of 2mSv/hr without shielding.

  • If handled at distances of 10 cm or more 1000 MBq
  • If handled at distances of less than 10 cm 10 MBq

Note that these quantities may be handled for a maximum of 15 minutes per day, five days a week, before the dose rate to the fingers is exceeded.

Effective Dose Coefficients

Inhalation coefficient

Ingestion coefficient

Skin dose coefficient

5.2 x 10-10 Sv.Bq-1 - 1μm AMAD

2.1 x 10-10 Sv.Bq-1

2.13 x 10-11 Gy.s-1 per Bq.cm-2


Classification

If the total quantity of cobalt - 57 in the laboratory is over 30 MBq it is necessary to classify the laboratory as a controlled area.

If the total quantity of cobalt - 57 in the laboratory is over 10 MBq, it is necessary to classify the laboratory as a supervised area.

*30 MBq if inhaled would give rise to an effective dose of 15 mSv.