Uranyl Acetate

Measurements on 100 gram sample of Uranyl Acetate. All measurements have been done above an open bottle.

1a. Alpha (α)    <2 counts/sec using a 540 scintillation meter with AP-2 Probe

1b. Beta (β)      >500 Counts/sec using a 540El probe coupled to a GM Meter (this determines beta events and some low energy gamma events.

1c. Gamma dose Rate (energy field) (g)

Two measurements done

1. Mini monitor type R with GM Probe - This is more specific to Gamma due in fact to being constructed to accept a narrow energy range (discriminates against beta) field: 0.6mR/hr (Mainly gamma)

2. Ionization chamber DMM 95/0500 - 1/6 for total Beta and Gamma energy field 5mR/hr (g + b)

Please note that a high efficiency scintillation counter will measure many of these events, but it will say nothing about the energy field. The customer must use a dose rate meter. (You can see the difference between the energy events and gamma dose rate) A Geiger counter just will not do the job.

2. Our uranium is U²³⁵ depleted. Typical Isotopic Composition is:

U²³⁸ - 99.9%

U²³⁵ - 0.1%

Natural Uranium has two main Isotopes: U²³⁸ & U²³⁵

Natural Isotopic composition would be:

U²³⁸ - 99.3%

U²³⁵ - 0.7%

That is to say material supplied by us is Uranium depleted i.e., the U²³⁵ content is reduced from 0.7% to between 0.3 - 0.4%. Both natural and depleted Uranium, being a mixture of isotopes and daughters, will be expected to demonstrate alpha, beta and gamma activity.

Radioactive Material

The average number of atomic transformations occurring per second is termed the activity of the radioactive material.

The old, traditional, unit of activity is Curie(Ci), which is defined as 3.7 x 10¹⁰ atomic transformations per seconds. For smaller quanitites the one-thousandth and one-millionth unit are used, namely the millicurie (mCi) and the microcurie (µCi).

However, by International agreement, the unit of activity is currently being changed. The new unit of activity is the becquerel (Bq) which is defined as one atomic tranformation per second. Bequerel is an extremely small unit. Larger units are used, namely the kilobecqueral (1kBq = 10³Bq), the megabecquerel ( 1 MBq = 10⁶Bq), the gigabecquerel (1 GBq = 10⁹Bq) and the tetrabecquerel (1 TBq = 10¹²Bq).

It may be noted that: 1 Ci = 3.7 x 10¹⁰Bq = 37GBq = 0.037TBq.

A material must have a specific activity greater than 74 bequerel per gram (Bq/g) (0.002µCi/g) or 74 kBq/kg in order to be regarded as a radioactive material.

Uranyl Acetate sold by ELECTRON MICROSCOPY SCIENCES has an activity of: U (depleated) .51µCi·gm^-1 (µCi = microcuries)

Formula for conversion to Bq is: 1 Ci = 3.7 x 10¹⁰Bq

∴ for U (depleated) Specific Activty = 0.51 x 10^-6 x 3.7 x 10¹⁰Bq·gm^-1 = 1.887 x 10⁴Bq·gm^-1
Uranyl Acetate Specific Activity (U approx. 55%) = 1.04 x 10⁴Bq·gm^-1

∴ Uranyl Acetate will exhibit 10, 400 disintegrations/sec/gm.