Requirements for Type B(U) packages

Type B(U) packages shall be designed to meet the requirements specified in 6.4.2, and of 6.4.7.2 to
6.4.7.15, except as specified in 6.4.7.14 (a), and, in addition, the requirements specified in 6.4.8.2
to 6.4.8.15.

A package shall be so designed that, under the ambient conditions specified in 6.4.8.5 and 6.4.8.6 heat
generated within the package by the radioactive contents shall not, under normal conditions of
carriage, as demonstrated by the tests in 6.4.15, adversely affect the package in such a way that it
would fail to meet the applicable requirements for containment and shielding if left unattended for a
period of one week. Particular attention shall be paid to the effects of heat, which may cause one or
more of the following:
(a) Alter the arrangement, the geometrical form or the physical state of the radioactive contents or,
if the radioactive material is enclosed in a can or receptacle (for example, clad fuel elements),
cause the can, receptacle or radioactive material to deform or melt;
(b) Lessen the efficiency of the packaging through differential thermal expansion or cracking or
melting of the radiation shielding material;
(c) In combination with moisture, accelerate corrosion.

A package shall be so designed that, under the ambient condition specified in 6.4.8.5 and in the
absence of insolation, the temperature of the accessible surfaces of a package shall not exceed 50 °C,
unless the package is carried under exclusive use.

The maximum temperature of any surface readily accessible during carriage of a package under
exclusive use shall not exceed 85 °C in the absence of insolation under the ambient conditions
specified in 6.4.8.5. Account may be taken of barriers or screens intended to give protection to persons
without the need for the barriers or screens being subject to any test.

The ambient temperature shall be assumed to be 38 °C.

The solar insolation conditions shall be assumed to be as specified in Table 6.4.8.6.
Table 6.4.8.6: Insolation data
 
 

Case

Form and location of surface

Insolation for 12 hours per day (W/m2)

1

Flat surfaces carried horizontally-downward facing

0

2

Flat surfaces carried horizontally-upward facing

800

3

Surfaces carried vertically

200a

4

Other downward facing (not horizontal) surfaces

200a

5

All other surfaces

400a

a Alternatively, a sine function may be used, with an absorption coefficient adopted and the effects
of possible reflection from neighbouring objects neglected.

A package which includes thermal protection for the purpose of satisfying the requirements of the
thermal test specified in 6.4.17.3 shall be so designed that such protection will remain effective if the
package is subjected to the tests specified in 6.4.15 and 6.4.17.2 (a) and (b) or 6.4.17.2 (b) and (c), as
appropriate. Any such protection on the exterior of the package shall not be rendered ineffective by
ripping, cutting, skidding, abrasion or rough handling.

 
A package shall be so designed that, if it were subjected to:
(a)      The tests specified in 6.4.15, it would restrict the loss of radioactive contents to not 
more      than 10-6 A2 per hour; and
(b)      The tests specified in 6.4.17.1, 6.4.17.2 (b), 6.4.17.3, and 6.4.17.4 and either the test 
in
 
(i)    6.4.17.2 (c), when the package has a mass not greater than 500 kg, an overall density     
not greater than 1 000 kg/m3 based on the external dimensions, and radioactive contents greater 
than 1 000 A2 not as special form radioactive material, or
(ii)     6.4.17.2 (a), for all other packages, it would meet the following requirements:
- retain sufficient shielding to ensure that  the  radiation level  at  1 m from the  surface  of 
the  package would not exceed 10 mSv/h with the maximum radioactive contents which the package is 
designed to contain; and
 
-      restrict the accumulated loss of radioactive contents in a period of one week to not more 
than    10 A2 for krypton-85 and not more than A2 for all other radionuclides.
Where mixtures of different radionuclides are present, the provisions of 2.2.7.2.2.4 to 2.2.7.2.2.6 
shall apply except that for krypton-85 an effective  A (i) value equal to 10 A        may be used.  
For case (a)
t shall take into account the external contamination limits of 4.1.9.1.2.
 

A package for radioactive contents with activity greater than 105 A2 shall be so designed that if it were
subjected to the enhanced water immersion test specified in 6.4.18, there would be no rupture of the
containment system.

Compliance with the permitted activity release limits shall depend neither upon filters nor upon a
mechanical cooling system.

A package shall not include a pressure relief system from the containment system which would allow
the release of radioactive material to the environment under the conditions of the tests specified in
6.4.15 and 6.4.17.

A package shall be so designed that if it were at the maximum normal operating pressure and it were
subjected to the tests specified in 6.4.15 and 6.4.17, the level of strains in the containment system
would not attain values which would adversely affect the package in such a way that it would fail to
meet the applicable requirements.

A package shall not have a maximum normal operating pressure in excess of a gauge pressure
of 700 kPa.

A package containing low dispersible radioactive material shall be so designed that any features added
to the low dispersible radioactive material that are not part of it, or any internal components of the
packaging shall not adversely affect the performance of the low dispersible radioactive material.
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