Working Rules for Sealed Radioactive School Sources

The laboratory demonstrator, assisting technician and students are responsible for ensuring:

• All sources are accounted for at the end of a laboratory or demonstration session.

• Sources are secured in their lockable cabinet or locked room at the end of the session.

• Experiments and demonstrations are conducted in such a way that recommended dose limits cannot be exceeded and that radiation exposures are trivial.

• Deliberate exposure of staff or students does not occur.

• Unaccounted, lost or damaged sources should be reported to the School Radiation Safety Officer (SRSO) and Radiation Safety Officer (RSO) extn 3938.

Damaged sources may present a contamination hazard that could be expensive to clean up or present a health hazard if resulting in internal contamination. If a source is damaged the DRSO or RSO must be contacted immediately. The area around the source must be isolated to prevent spread of contamination by movement of equipment or people.

Sources should be handled with a tweezers. Using 10 cm DISTANCE from the source can reduce the radiation dose to your fingers by as much as 10,000 times.

SHIELDING should be provided where the source is in close proximity (less than 50 cm) to students for extended periods of time (over an hour), and should be lead. For the activities of schools sources listed below radiation levels are so low that no special shielding is required.

TIME near radioactive sources should be kept to a minimum, for example holding a radioactive source in your fingers for an extended period is very poor practice.

²⁴¹Am emits alpha particles and is bonded to an open metal surface in a shallow well of the source disk. Do not touch or physically damage this surface as ²⁴¹Am CONTAMINATION may result.

ACTIVITY of sources used should be kept to a practical minimum. Recommended activity limits for school sources are:

⁵⁷Co Mossbauer sources can have very high activities. These sources should only be used with 2^nd and 3^rd year students. The radiation hazards must be carefully explained in the laboratory notes and verbally by the supervisor prior to commencing the experiment. Under no circumstances should the source be handled with fingers. The source must be shielded where ever possible, 5 mm lead is generally sufficient. The ⁵⁷Co is plated on the surface of the source and physical contact with this surface is to be avoided at all times.

Reference: NH&MRC Code of Practice for the Safe Use of Ionizing Radiation in Secondary Schools (1986)