Paragraph 5
The individual package damaged or undamaged shall be subcritical under the conditions specified in paragraphs 3 and 4 taking into account the physical and chemical characteristics including any change in those characteristics which could occur when the package is damaged and with the conditions of moderation and reflection as specified below:
For all material within the containment system: the material arranged in the containment system
in the configuration and moderation that results in maximum neutron multiplication; and
with close reflection of the containment system by water 20 cm thick (or equivalent) or such greater reflection of the containment system as may additionally be provided by the surrounding material of the packaging; and, in addition
If any part of the material escapes from the containment system: that material arranged in
the configuration and moderation that results in maximum neutron multiplication; and
with close reflection of that material by water 20 cm thick (or equivalent).