M9.2
TRANSPORT OF RADIOACTIVE MATERIAL
(Target audience: Consignors of Nucleonic Gauges with Low Activity Sources)
(Mode: Sea)
Scope of this module
This module relates to the regulatory requirements for the safe transport of low activity radioactive material by sea 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.
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.
Tasks before the consignor
The consignor should –
a)Know the regulations
b)Ensure that a radiation protection programme and a quality assurance programme are in place and implemented
c)Select the package in which the radioactive material has to be transported
d)Procure an appropriate package
e)Prepare the package for transport (e.g. load the radioactive material in the package, seal the package, check the radiation and contamination levels)
f)Mark and label the package
g)Complete the transport documents
h)Forward the package
Regulatory requirements
The IAEA Regulations [1] form the basis of many national and international regulations for transport of radioactive material. The assignment of responsibilities to consignor, carrier and the consignee would be determined by the laws and customs of different countries and the international conventions into which the countries have entered.
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. 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 national and international regulations for the safe transport of radioactive material because of the difference in the legal system among the states.
International Maritime Organization (IMO)
The International Maritime Organization (IMO) is a United Nations agency. The regulations, standards and recommendations (IMDG Code) that it has developed, are recognized, followed, and observed by ships of many nations. This code includes provisions for the transport of radioactive material by sea.
In addition, there is the MERCOSUR/MERCOSUL agreement that concerns road, rail, air and sea transport among certain South American countries.
Other dangerous properties of contents
If the radioactive material contained in the package has any other dangerous properties, such as explosiveness, flammability, pyrophoricity, chemical toxicity and corrosiveness, the package should be transported in compliance with the relevant transport regulations for dangerous goods of each of the countries through or into which the materials will be transported. In addition, the regulations of the concerned transport organizations should also be complied with.
Radiation protection requirements and quality assurance
Establishment of a Radiation Protection Programme
A Radiation Protection Programme (RPP) should be established for the transport of radioactive material. The nature and extent of the measures to be employed in the programme should be related to the magnitude and likelihood of radiation exposures. The RPP documents should be made available, on request, for inspection by the relevant competent authority. A sample RPP is given in appendix 1.
For occupational exposures arising from transport activities, where it is assessed that the effective dose may exceed:
(a) 1 mSv but not exceed 6 mSv in a year, workplace monitoring or individual monitoring should be conducted to assess the dose;
(b) 6 mSv in a year, individual monitoring should be conducted.
When individual monitoring or workplace monitoring is conducted, appropriate records should be kept. The Agency has published a Safety Guide on Radiation Protection Programmes for Transport of Radioactive Material [5].
Emergency preparations
In the event of accidents or incidents during the transport of radioactive material, emergency provisions, as established by relevant national and/or international organizations, should be observed to protect persons, property and the environment..The Agency has published a Safety Guide emergency preparedness for transport accidents.[6].
Training of personnel
Workers directly engaged in any activity involving packages containing radioactive material should receive appropriate training concerning radiation protection.
Persons engaged in the transport of radioactive material should receive training in the contents of the Regulations commensurate with their responsibilities.
Individuals such as those who classify radioactive material; pack radioactive material; mark and label radioactive material; prepare transport documents for radioactive material; offer or accept radioactive material for transport; carry or handle radioactive material in transport; mark or placard or load or unload packages of radioactive material into or from transport vehicles, bulk packagings or freight containers; or are otherwise directly involved in the transport of radioactive material as determined by the competent authority; should receive the following training:
(a) General awareness/familiarization training:
(i) The general provisions of the Regulations;
(ii) Description of the categories of radioactive material; labelling, marking, placarding and packaging and segregation requirements; a description of the purpose and content of the radioactive material transport document; and a description of available emergency response documents;
(b) Requirements which are specific to the function that person performs;
(c) (i) Methods and procedures for accident avoidance;
(ii) Emergency response information and how to use it; and
(iii) Risk posed by the various categories of radioactive material and measures to prevent exposure.
Records of all safety training undertaken should be kept by the employer and made available to the employee if requested.
The training required above should be provided upon employment and should be periodically supplemented with retraining as deemed appropriate by the competent authority.
Quality Assurance
Quality assurance programmes should be established and implemented for transport operations. They should be based on international, national or other standards acceptable to the competent authority. This will ensure compliance with the Regulations. Certification that the design specification has been fully implemented should be available to the competent authority. The consignor should be prepared to demonstrate to the competent authority that all packagings are periodically inspected and, as necessary, repaired and maintained in good condition so that they continue to comply with all requirements even after repeated use.
Definitions of terms
Certain terms are assigned specific meanings in the Regulations. For example the terms contamination menas 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.
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 by air
Radionuclide / Use of the radioactive material / Typical activity(TBq) / A1
(TBq) / A2
(TBq)
Cobalt-60 / Level gauge / 0.2 / 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.
The consignor must be able to provide documentary evidence of compliance of the Type A package design with all applicable requirements.
Competent authority approval is not required for a Type A package intended for the transport of radiopharmaceuticals. However, the consignor must, on request, make available for inspection by the relevant competent authority the above mentioned documentary evidence.
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.
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].
Approval requirements
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.
The design for special form radioactive material requires unilateral approval.
Competent authority is not required for a Type A package intended for the transport of nuclear gauge sources.
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.
Control of radiation level
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.
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 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 any hold, compartment, or defined deck area of a vessel 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.
While under exclusive use, the radiation level on the external surface of the package or overpack or freight container should not exceed 10 mSv/h.
If the radiation level at any point on the external surface of a package or overpack exceeds 2 mSv/h, it may be transported only under special arrangement.
There is a special case of exception to this requirement. That is, if the radiation level at any point on the external surface of a package or overpack exceeds 2 mSv/h, it may be transported by ship without the need for special arrangement provided the following conditions are met:
a)The packages or overpacks should be carried in a vehicle on board the vessel.
b)The packages or overpacks should be transported in the vehicle under exclusive use conditions as per the regulations for transport by road/rail.
c)The packages or overpacks should not be removed from the vehicle at any time while on board the vehicle.
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 vessels or storage areas. However, it is good practice to check and confirm that the limits on contamination are not exceeded.
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 vessels.
Transport of other goods with radioactive shipment
Only items that are necessary for the use of the radioactive material should be contained in the package. There should be no interaction between these items and the package which could reduce the safety of the package.
If packagings are to be used for the storage or transport of other goods, then the package should first be decontaminated.That is, the level of contamination should be within these limits:
(a) 0.4 Bq/cm2 for beta and gamma emitters and low toxicity alpha emitters and
(b) 0.04 Bq/cm2 for all other alpha emitters.
Categorisation of packagesand overpacks
Packages and overpacks should be assigned to either category I-WHITE, II-YELLOW or III-YELLOW. The table given below provides the criteria for such categorisation. This is a necessary prerequisite to labelling and placarding.
table: categories of packages and overpacks
Transport indexMaximum radiation level atCategory
any point on external surface
0aNot more than 0.005 mSv/hI-White
More than 0 but not more than 1a More than 0.005 mSv/h but
not more than 0.5 mSv/hII-Yellow
More than 1 but not more than 10 More than 0.5 mSv/h but
not more than 2 mSv/hIII-Yellow
More than 10 More than 2 mSv/h but
not more than 10 mSv/hIII-Yellow b
aIf the measured TI is not greater than 0.05, the value quoted may be zero.
bShould also be transported under exclusive use.
Where the transport index of a package or overpack satisfies the condition for one category but the surface radiation level satisfies the condition for a different category, the package or overpack should be assigned to the higher category. Category III-YELLOW is higher than Category II-YELLOW which is higher than Category I-WHITE.The category of a package should be determined on the basis of measured radiation levels, considering the package in isolation.