Internal Monitoring Equipment

Question 1

What type of radiation does internal monitoring equipment search for?

Answer 1

Gamma radiation.

Question 2

What are the four Radiacs used for Internal Monitoring, and what are their Minimal Detectable Activities (Co-60 equivalent)?

Answer 2

FASTSCAN MCA: 2nCi
Canberra 35N/Canberra ASA-100: 5nCi
PRM-5 w/ SPA-3 Probe: 10 nCi

Question 3

Explain the principle behind scintillation.

Answer 3

Kinetic Energy of Ionizing Radiation is converted into Light.

• Radiation hits the crystal and frees an electron, creating a positively charged “hole.”
• The negative and positive charge travel to an activator site (aka the Thallium impurity) and create a space for the electron, which settles there.
• The electron emits a light photon as it de-excites.

Question 4

List when P-5055 says to do internal monitoring.

Answer 4

1. Adults likely to receive 10% ALI/yr.
2. Minors likely to receive CEDE >100mRem.
3. Declared Pregnant Workers likely to receive 100mRem during pregnancy.
4. Anyone who potentially inhaled/ingested/absorbed/injected radioactive material as a result of a mishap.
5. When deemed necessary by medical officer, RHO, rad health director.
6. Not more than 3 months before starting duties with the potential of internal intake.
7. Periodically on individuals performing duties involving potential of internal intake.

Question 5

List when NNPP says to do internal monitoring.

Answer 5

Nuclear trained personnel authorized to receive occupational exposure receive monitoring.

1. Prior to being authorized to receive exposure.
2. Near as practical, but at least within 180 days of separation from Naval Service or transferred out of a NNPP billet.
3. When wetted above the waist.
4. When there is documented skin contamination.
5. Periodically in conjunction with medical exam.
6. In conjunction with an RME.
7. When deemed necessary by the RHO.