Requirements for Type B U packages

Type B(U) packages shall be designed to meet the requirements specified in paras 606-616, the requirements of paras 617-619 if carried by air, and of paras 634-647, except as specified in para. 646(a), and, in addition, the requirements specified in paras 651-664. 

A package shall be so designed that, under the ambient conditions specified in paras 654 and 655, heat generated within the package by the radioactive contents shall not, under normal conditions of transport, as demonstrated by the tests in paras 719-724, 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  

A package shall be so designed that, under the ambient condition specified in para. 654 and in the absence of insolation, the temperature of the accessible surfaces of a package shall not exceed 50° C, unless the package is transported under exclusive use. 

Except as required in para. 617 for a package transported by air, the maximum temperature of any surface readily accessible during transport of a package under exclusive use shall not exceed 85°C in the absence of insolation under the ambient conditions specified in para. 654. 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 solar insolation conditions shall be assumed to be as specified in Table 11. 

The concept of a Type B(U) package is that it is capable of withstanding most of the severe accident conditions in transport without loss of containment or increase in external radiation level to an extent which would endanger the general public or those involved in rescue or cleanup operations. It should be safely recoverable (see paras 510 and 511), but it would not necessarily be capable of being reused. 

The evaluation to ambient temperature conditions must account for heat generated by the contents, which may be such that the maximum temperature of some package components may be considerably in excess of the maximum of 70°C required for a Type A package design. 

Practical tests may be used to determine the internal and external temperatures of the package under normal conditions by simulating the heat source due to radioactive decay of the contents with electrical heaters. In this way, the heat source can be controlled and measured. Such tests should be performed in a uniform and steady thermal environment (i.e. fairly constant ambient tanperature, stiU air and minimum heat input from external sources such as sunlight). The package with its heat source should be held under test for sufficient time to allow the temperatures of interest to reach steady state. The test ambient temperature and internal heat source should be measured and used to adjust linearly all measured package temperatures to those corresponding to a 38 C ambient temperature. 

With a snrface temperature limit of 50°C at the maximum ambient temperature of 38°C, other cargo will not become overheated nor will anyone handling or touching the surface suffer a bum. A higher surface temperature is permitted under exclusive use (except for transport by air) see para. 662 of the Regulations and paras 662.1-662.4. 

The insolation data provided in Table XI of the Regulations are uniform heat fluxes. They are to be applied at the levels stated for 12 h (daylight) followed by 12 h of no insolation (night). The cyclic step functions representing insolation should be applied until the temperatmes of interest reach conditions of steady periodic behaviour. 

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Type B(M) packages shall meet the requirements for Type B(U) packages specified in para. 650, except that for packages to be transported solely within a specified country or solely between specified countries, conditions other than those given in paras 637,653-655 and 658-664 above may be assumed with the approval of the competent authorities of these countries. Notwithstanding, the requirements for Type B(U) packages specified in paras 653 and 658-664 shall be met as far as practicable. 

The requirement that the MNOP not exceed 700 kPa gauge is the specified limit for Type B(U) packages to be acceptable for unilateral approval. 

The surface temperature limit of 85°C for Type B(U) packages under exclusive use, where potential damage to adjacent cargo can be well controlled, is required... 

An application for approval of a Type B(M) package design shall include, in addition to the information required in para. 807 for Type B(U) packages ... 

Users of the Regulations should be aware that a Member State may require in its national regulations that an additional approval be given by its competent authority for any special form radioactive material, Type B(U) and Type C package which is to be used for domestic transport on its territory, even if the design has already been approved in another country. 

The leaktightness requirement for a containment system in a Type B(U), Type B(M) or Type C package depends on the radiotoxicity of the radioactive contents for example, a Type B(U) or Type C package under accident conditions must have the release limited to a value of in the period of a week. This connection to the A2 value means that for highly toxic radionuclides such as plutonium and americium the allowable volumetric leak rate will be much lower than for low enriched uranium. However, if fissile material is able to escape from the contaimnent system under accident conditions, it must be demonstrated that the quantity that escapes is consistent with that assumed in the criticality safety assessment in applying para. 682(c). 

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