49 CFR § 173.468 - Test for LSA-III material.
(a) LSA-III Class 7 (radioactive) material must meet the test requirement of paragraph (b) of this section. Any differences between the material to be transported and the test material must be taken into account in determining whether the test requirements have been met.
(1) The specimen representing no less than the entire contents of the package must be immersed for 7 days in water at ambient temperature.
(2) The volume of water to be used in the test must be sufficient to ensure that at the end of the test period the free volume of the unabsorbed and unreacted water remaining will be at least 10% of the volume of the specimen itself.
(3) The water must have an initial pH of 6-8 and a maximum conductivity of 10 micromho/cm at 20 °C (68 °F).
(4) The total activity of the free volume of water must be measured following the 7 day immersion test and must not exceed 0.1 A2.