Tests for special form radioactive material

TESTS FOR SPECIAL FORM RADIOACTIVE MATERIAL General 

The four test methods specified in the Regulations, namely the impact, percussion, bending and heat tests, are intended to simulate mechanical and thermal effects to which a special form radioactive material might be exposed if released from its packaging. 

These test requirements are provided to ensure that special form radioactive materials which become immersed in liquids as a result of an accident will not disperse more than the limits given in para. 603. 

The tests of a capsule design may be performed with simulated radioactive material. The term simulated means a facsimile of a radioactive sealed source, the capsule of which has the same construction and is made with exactly the same materials as those of the sealed sonrce that it represents, but contains, in place of the radioactive material, a substance with mechanical, physical and chemical properties as close as possible to those of the radioactive material and containing radioactive material of tracer quantities only. The tracer should be in a form soluble in a solvent which does not attack the capsule. One procedure described in ISO 2919 [1] utilizes either 2 MBq of Sr-90 and Y-90 as soluble salt, or 1 MBq of Co-60 as soluble salt. When possible, shorter lived nnclides should be used. However, if leaching assessment techniqnes are used, care needs to be taken when interpreting the results. The effects of scaling will have to be introduced, the importance of which will depend upon the maximum activity to be contained within the capsule and also the physical form of the intended capsule contents, particularly the solubility of the intended capsule contents as compared with the tracer radionuclide. These problems can be avoided if volumetric leakage tests are used (see paras 603.3 and 603.4). Typically, tests for special form radioactive material are performed on full scale sealed sources or indispersible soUd material because these are not expensive and the results of the tests are easy to interpret. 

Since this test is intended to be analogons to the Type B(U) package 9 m drop test (see para. 603.1), the specimen shonld be dropped so as to suffer maximnm damage. 

Specimens that comprise or simulate special form radioactive material shall be subjected to the impact test, the percussion test, the bending test and the heat test specified in paras 705-709. A different specimen may be used for each of the tests. Following each test, a leaching assessment or volumetric leakage test shall be performed on the specimen by a method no less sensitive than the methods given in para. 710 for indispersible solid material or in para. 711 for encapsulated material. 

Impact test The specimen shall drop onto the target from a height of 9 m. The target shall be as defined in para. 717. 

Percussion test The specimen shall be placed on a sheet of lead which is supported by a smooth sohd surface and struck by the flat face of a mild steel bar so as to cause an impact equivalent to that resulting from a free drop of 1.4 kg through 1 m. The lower part of the bar shall be 25 mm in diameter with the edges rounded off to a radius of (3.0 0.3) mm. The lead, of hardness number 3.5 to 4.5 on the Vickers scale and not more than 25 mm thick, shall cover an area greater than that covered by the specimen. A fresh surface of lead shall be used for each impact. The bar shall strike the specimen so as to cause maximum damage. 

Heat test The specimen shall be heated in air to a temperature of 800°C and held at that temperature for a period of 10 minutes and shall then be allowed to cool. 

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