M18.3
TRANSPORT OF RADIOACTIVE MATERIAL
(Target audience: Users of Nucleonic Gauges with Low Activity Sources)
(Mode of transport: Road / Rail / Inland waterway)
Introduction
Transport radioactive material is governed by national and international regulations. The International Atomic Energy Agency (IAEA) has published the Regulations for the Safe Transport of Radioactive Material [1]. All references to “Regulations” in this module pertain to the IAEA Regulations. The objective of the Regulations is to establish requirements that must be satisfied to ensure safety and to protect persons, property and the environment from the effects of radiation in the transport of radioactive material. This protection is achieved by requiring, among others:
a)containment of the radioactive contents; and
b)control of external radiation levels.
These requirements are satisfied first by specifying -
a)performance standards for package design based on the radioactive contents and
b)administrative controls and
c)approval by competent authorities.
Confidence in this regard is achieved through quality assurance and compliance assurance programmes.
Scope of this module
This module relates to the regulatory requirements for the safe transport of low activity radioactive material by road, rail and inland waterway craft to facilities handling radioactive sources for industrial process control such as measurement of level of fluids, density of substances, thickness of products like paper, plastic sheets and metal sheets and moisture content in materials. This module also considers examples of decayed sources removed from a large number of gauges which may be transported in a single package back to the supplier’s facility for disposal.This moduledescribes how the transport of these materials can be carried out in conformity with the applicable regulatory requirements.
Tasks before the consignor
The consignor should –
a)Familiarize himself with the regulations
b)Select the package in which the radioactive material has to be transported
c)Procure an appropriate package
d)Obtain the necessary approvals from the concerned competent authority/authorities
e)Prepare the package for transport (e.g. load the radioactive material in the package, fasten the closure, decontaminate the exterior of the package)
f)Mark and label the package
g)Conduct the tests before the shipment
h)Complete the transport documents including consignor’s declaration and information to the carrier.
i)Forward the package through a carrier
j)Implement radiation protection requirements and quality assurance
Familiarization with regulatory requirements
IAEA Regulations
The IAEA Regulations [1] form the basis of many national and international regulations for transport of radioactive material.
The Agency has published a Safety Guide advising the user about how the regulatory requirements can be satisfied [2]. In order to guide the consignor through the regulatory requirements, IAEA has published the Schedules for the Regulations as a Safety Guide [3]. The schedules provide specific guidance on the regulatory requirements for each type of consignment.
National Regulations
Transport of radioactive material is governed by national regulations of each State. Member States of IAEA adopt the IAEA Regulations within the frame work of the local laws and the international conventions to which the nation is a party. Accordingly, responsibilities are assigned in the National regulations to consignor, carrier and consignee. Consignors, carriers and the concerned public authorities ensure that the shipments are made in compliance with the applicable national regulations. There could be some differences between the national regulations and the international regulations for the safe transport of radioactive material because of the difference in the legal system among the states.
Regional agreements for modal transport
The transport of dangerous goods by road, rail and inland waterway modes is not covered by an international organization on a worldwide basis. Rather, these are covered by several regional agreements such as:
a)The Regulations Concerning the International Carriage of Dangerous Goods by Rail (RID),
b)The European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR),
c)The European Agreement concerning the International Carriage of Dangerous Goods on Inland Waterways (ADN) and
d)The Regulations for the Transport of Dangerous Goods on the Rhine (ADNR).
e) The MERCOSUR/MERCOSUL agreement
These instruments referred to in (a) to (d) were established in Europe.
The MERCOSUR/MERCOSUL agreement covers road, rail, air and sea transport among certain South American countries.
Definitions of terms
Certain terms are assigned specific meanings in the Regulations. For example the terms contamination means the presence of a radioactive substance in excess of 0.4 Bq/cm2 for beta, gamma and low toxicity alpha emitters or 0.04 Bq/cm2 for other alpha emitters. The term conveyance includes road vehicles, rail cars, vessels or aircraft. A packaging together with the radioactive content is defined as package. Many definitions are provided in the Regulations. It is necessary to understand the meanings assigned to various terms in the Regulations.
A1 values and A2 values
Familiarity with A1 and A2 values defined in the Regulations would be useful. Radioactive material may be transported either in special form (essentially indispersible) and other form. The A1 value refers to the activity of special form radioactive material and the A2 value refers to the activity of other than special form radioactive material.The values of A1 and A2 have been determined for most common radionuclides and are listed in the Regulations. Multiples and fractions of A1 and A2 (for example, 3000A1, 10-3 A1, 3000A2 and 10-4 A2) are used in specifying criteria throughout the Regulations.
Selection of Package
The type of package for the transport of radioactive material is determined by the radionuclide and its activity to be transported. Let us consider the following typical examples of radioactive materials considered in this module.
Table: Examples of nuclear gauge sources transported
Radionuclide / Use of the radioactive material / Typical activity(TBq) / A1
(TBq) / A2
(TBq)
Cobalt-60 / Level gauge / 0.1 / 0.4 / 0.4
Caesium-137 / Level guage / 0.2 / 2 / 0.6
Caesium-137 / Density gauge / 0.08 / 2 / 0.6
241 Am / Level gauge / 0.004 / 10 / 0.001
241 Am / Thickness gauge / 0.02 / 10 / 0.001
Caesium-137 / Moisture gauge / 0.0004 / 2 / 0.6
The radioactive materials considered in this module need to be transported in activities within the A1 and A2 values. Sothey can be transported in a Type A packaging. Type A packages are of simple design. Therefore, the total activity of a radioactive material that is permitted to be transported in a Type A package is subject to limits.
Procurement of a package of currently approved design
Generally gauges are required to be of sturdy design for field use. Sources are transported in the gauges themselves. In view of the small activity of the radioactive material contained in a gauge, the gauges may need to be simple Type A packages. There can be instances where a Type B(U)/(M) package may be required. For example, some times decayed sources removed from a large number of gauges may be transported from the user’s facility in a single package for disposal. If the total activity of all the sources in a single package exceeds, A1 or A2, the package has to be of Type B(U) or Type B(M). The design of packages used for transport of large quantities of radioactive material is subjected to approval by the competent authority. Such approval could be either unilateral [The letter U in the designation Type B(U) represents Unilateral approval.], or multilateral [The letter M in the designation Type B(M) represents Multilateral approval.]. Certain design features of the packaging determine the need for obtaining multilateral approval.
In many countries the sources used in gauges are required to be designed to meet standards specified by the International Organization for Standardization (ISO) [4]. Many such sources may be deemed to be special form provided they satisfy the applicable requirements prescribed in the Regulations [1].
Tests before first shipment
Before procuring the packaging, the consignor has to ensure that the supplier of the package has subjected it to the acceptance tests and confirmed that the package has been manufactured in complete conformance with the approved design.
Special arrangement
If conformity with some of the provisions of the Regulations is not practicable, the consignment can be transported but only under special arrangement. Approval for transport under special arrangement should be obtained from the concerned competent authorities.
Obtaining necessary approvals from the competent authority
Approval of package for the transport of nuclear gauge sources
The approval requirements for the sources discussed in this module are two-fold: Design approval and shipment approval. Design approval applies to sources (special form radioactive material) and packages. Shipment approval applies to the carriage of certain packages.
Competent authority approval is not required for a Type A package intended for the transport of nuclear gauge sources. In some countries, in the absence of an approval procedure, the design of Type A packages for nuclear gauges is required to be registered with the competent authority.
The consignor should ensure the following:–
a)The package, if it is of Type B(U)/(M), is of approved design and the design approval certificate would remain valid until the completion of the shipment
b)In case of Type B(M) package, multilateral approval is obtained from the concerned competent authorities.
c)If the radioactive material is declared as a special form radioactive material the design approval certificate of the radioactive material would be valid until completion of the shipment.
Approval of Type B(U) package designs
The design of a Type B(U) package requires unilateral approval.
Approval of Type B(M) package designs
Each Type B(M) package design would require multilateral approval.
Approval of Shipments
Multilateral approval is required for the shipment of a Type B(M) package if :
a)if its design does not take into account temperatures ranging from – 40 °C to + 70 °C for the components of the packaging
b)is designed to allow controlled intermittent venting or
c)the activity of the radioactive material exceeds 3000A1 or 3000A2, as appropriate, or 1000 TBq, whichever is the lower.
An application for shipment approval should include:
a)the period of time, related to the shipment, for which the approval is sought;
b)the actual radioactive contents, the expected modes of transport, the type of conveyance and the probable or proposed route; and
c)the details of how the precautions and administrative or operational controls, referred to in the package design approval certificates are to be put into effect.
Approval of Shipments under Special Arrangement
If a consignment is transported under special arrangement multilateral approval is required. The competent authority needs to be satisfied that the overall level of safety in transport is at least equivalent to that which would be provided if all the applicable requirements of these Regulations had been met.
An application for approval of shipments under special arrangement should include:
a)A statement of the respects in which the shipment cannot be made in full accordance with the applicable requirements and the reasons; and
b)A statement of any special measures which are to be implemented to compensate for the failure to meet the applicable requirements.
Preparation of the package for transport
Limits on package content
The actual value of the limit for a radionuclide that can be transported in a Type A package depends upon the physical form of the radionuclide. Two forms are considered for transport in a Type A package, viz., special form (essentially indispersible) and other form.
The maximum activity of special form radioactive material that is permitted in a Type A package is designated as A1.
The maximum activity of other than special form radioactive material that is permitted in a Type A package is A2.
The total quantity of radioactive material that is transported in a Type B(U)/B(M) package should not exceed the limit specified in the package approval certificate issued by the competent authority.
Control of external exposure
External exposure that may result from the transport of these sources is controlled. The Regulations impose two limits on the radiation level outside the package. One limit restricts the radiation level at the external surface of the package. The other limit restricts the radiation level at one metre from the external surface of the package. The latter number is referred to as the transport index of the package.
Transport Index (TI)
The TI is an indicator of the radiation level in the vicinity of a package or freight container. It is useful in determining the segregation distances from packages, overpacks and freight containers. The segregation distance is calculated using the inverse square law of reduction of radiation level from package. In the case of large packages radiation levels external to the loads do not decrease as per the inverse square law. Therefore a multiplication factor is introduced for large dimension loads.Segregation distances should be calculated on the basis of the TI indicated on these loads.
Here is the procedure for determining the TI of a package or overpack or freight container:
Determine the TI of a package on the basis of measured radiation levels, considering the package in isolation. Scan the package, including the top and bottom, at a distance of 1 m from the external surface. Ignore protrusions on the exterior of the package in determining the 1 m distance.
Determine the maximum radiation level in units of millisieverts per hour (mSv/h) at a distance of 1 m from the external surfaces of the package, overpack, freight container.Multiply it by 100. The resulting number is the transport index of the package / overpack. In the case of freight containers this value should bemultiplied by the factor given in the table below appropriate to the size of the freight container.
table: Multiplication factors for FREIGHT CONTAINERS
Size of loadaMultiplication factor
size of load 1 m21
1 m2size of load 5 m22
5 m2size of load 20 m23
20 m2<size of load10
aLargest cross-sectional area of the load being measured.
The value obtained above should be rounded up to the first decimal place (e.g. 1.13 becomes 1.2), except that a value of 0.05 or less may be considered as zero.
Alternatively, the TI for a freight container may be established as the sum of the TIs of all the packages in the freight container.
Many packages may be transported in a rigid overpack or a freight container or an aircraft. The TI,in this case, may be taken as either the sum of the TIs of all the packages contained, or by direct measurement of radiation level. Adding the TIs reflects a conservative approach as the sum of the TIs of the packages contained may be higher than the maximum radiation level at 1 m from the external surface of the overpack or the freight container due to shielding effects and the additional distance from the packages in the core of the consignment.
Limits on T I and Radiation Levels
The radiation level at any point on the external surface of a package or overpack or freight container should not exceed 2 mSv/h. If this limit is exceeded, the consignment could be permitted only under exclusive use.
The transport index of any package or overpack or freight container should not exceed 10. If this limit is exceeded, the consignment could be permitted only under exclusive use.
Exclusive use means that
a)a single consignor will have the sole use of a conveyance or of a large freight container;
b)all initial, intermediate and final loading and unloading will be carried out in accordance with the directions of the consignor or consignee; and
c)the consignor has primary responsibility for ensuring compliance.
For consignments under exclusive use, the radiation level should not exceed:
(a) 10 mSv/h at any point on the external surface of any package or overpack, and may only exceed 2 mSv/h provided that:
(i) the vehicle is equipped with an enclosure which, during routine conditions of transport, prevents the access of unauthorized persons to the interior of the enclosure;
(ii) provisions are made to secure the package or overpack so that its position within the vehicle enclosure remains fixed during routine conditions of transport; and
(iii) there is no loading or unloading during the shipment;
(b) 2 mSv/h at any point on the outer surfaces of the vehicle, including the upper and lower surfaces, or, in the case of an open vehicle, at any point on the vertical planes projected from the outer edges of the vehicle, on the upper surface of the load, and on the lower external surface of the vehicle; and
(c) 0.1 mSv/h at any point 2 m from the vertical planes represented by the outer lateral surfaces of the vehicle, or, if the load is transported in an open vehicle, at any point 2 m from the vertical planes projected from the outer edges of the vehicle.
In the case of road vehicles, no persons other than the driver and assistants should be permitted in vehicles carrying packages, overpacks or freight containers bearing category II-YELLOW or III-YELLOW labels.
Transport of vehicles loaded with radioactive material by vessels
Sometimes vehicles loaded with packages or overpacks are transported by vessels. Transport of such vehicles in vessels is permitted provided that (a) the vehicles satisfy the applicable requirements for transport by rail / road and (b) the packages or overpacks are not removed from the vehicle while on board the vessel. If the transport index of a package or overpack is greater than 10 it can be transported only under exclusive use.
Controls for Contamination
The radioactive materials which are specifically addressed in this module are sealed sources. In many countries such sealed sources are required to satisfy the applicable requirements for sealed sources specified by the International Organization for Standardization (ISO) [4]. Hence these radioactive materials are unlikely to cause the spread of contamination on the package or a conveyance or storage areas. However, it is good practice to check and confirm that such transfer has not occurred.
The non-fixed contamination on the external surface of any package should be kept as low as practicable. The most effective way to ensure this is to prevent the surfaces from becoming contaminated. It is advisable to check gloves or other items of clothing of personnel routinely handling packages. Under routine conditions of transport non-fixed contamination on the external surface of any package should not exceed the following limits:
a)4 Bq / cm2 for β and γ emitters and low toxicity α emitters and
b)0.4 Bq/cm2 for all other α emitters.
Low toxicity alpha emitters are: natural uranium; depleted uranium; natural thorium; uranium-235 or uranium-238; thorium-232; thorium-228 and thorium-230 when contained in ores or physical and chemical concentrates; or alpha emitters with a half-life of less than 10 days. These limits are applicable when averaged over any area of 300 cm2 of any part of the surface. These limits apply also to the external and internal surfaces of overpacks, freight containers and conveyance.