Iron-55 (Fe-55) - doe-hdbk-1106-97

DOE-HDBK-1106-97

Instructor's Notes

IRON-55 (Fe-55)

Iron-55 decays by electron capture and so is an X-ray emitter. Fe-55

contamination may be detected by a thin-window G-M probe looking

at the very low-energy characteristic Mn X-rays. Manganese is

formed when the iron nucleus captures an electron. The manganese

emits X-rays characteristic to its electron shell structure. Liquid

scintillation counting may also be used.

1. Average X-ray energy: Electron capture with an average

low energy of 0.006 MeV.

2. IAEA toxicity classification: Medium-low.

3. Physical half-life: 2.6 years.

4. Effective half-life (Teff): 370 days.

5. Critical organ:

Liver and spleen for inhalation.

Lower large intestine for ingestion.

6. Personnel monitoring: Uptakes evaluated by analysis of

blood.

7. ALI:

2 mCi (7 x 107 Bq) by inhalation, daily Clearance.

9 mCi (3 x 108 Bq) by ingestion.