This instruction applies to UN3345

The following packagings are authorized:

1) Outer packagings constructed of suitable material, and of adequate strenght and design in relation to the packaging capacity, and its intended use, shall be used. Where this packaging instruction is used for the carriage of inner packagings of combination packagings the packaging shall be designed and constructed to prevent inadvertent discharge during normal conditions of carriage.

2) Packaging conforming to the following:
(a) An inner packaging comprising:
(i) primary receptacle(s) and a secondary packaging, the primary receptacle(s) or the secondary packaging shall be leakproof for liquids or siftproof for solids;
(ii) for liquids, absorbent material placed between the primary receptacle(s) and the secundary packaging.
The absorbent matrial shall be in quantity sufficient to absorb the entire contents of the primary receptacle(s) so that any release of the liquid substance will not comprimise the integrity of the cushioning material or of the outer packaging;
(iii) if multiple fragile primary receptacle(s) are placed in a single secondary packaging they shall be individually wrapped or separated to prevent contact between them;

(b) An outer packagingshall be strong enough for its capacity, mass and intended use, and with the smallest external dimension of at least 10o mm.

For carriage, the mark illustrated below shall be displayed on the external surface of the outer packaging on a background of contrasting colour and shall be cleary visible and legible. The mark shall be in the form of a square set a an angle of 45° (diamond-shaped) with each side having a lenght of at least 50 mm, the width of the line be at least 2 mm and the letters and numbers shall be at least 6 mm high.
Additional requirements:

Ice, dry ice and liquid nitrogen

When dry ice of liquid nitrogen is used, all applicable requirements of ADR shall be met. When used, ice or dry ice shall be placed outside the secondary packagings or an overpack.
Interior supports shall be provided to secure the secondary packagings in the orginal position after the ice or dry ice has dissipated. If ice is used, the outside packaging or overpack shall be leakproof. If carbon dioxide, solid (dry ice) is used , the packaging shall be designed and contructed to permit the release of carbon dioxide to prevent a build-up of pressure that could rupture the packagings. The outer package or overpack shall be marked "Carbon dioxide, solid" or "Dry ice". The primary receptacle and the secondary packaging shall maintain their integrity at the temperature of the refrigerant used as well as the temperatures and the pressures which could result if refrigeration were lost.

Note: if dry ice is used , there are no other requirements to be met.
If liquid nitrogen is used, it is sufficient to comply with Chapter 3.3, special provison 593:
(This gas, intended for the cooling of e.g. medical or biological specimens, if contained in double wall receptacles which comply with the provisions of packing instruction P203, paragraph (6) for open cryogenic receptacles of of ADR is not subject to the requirements of ADN)

Reference: WHO (updated June 2018)