Requirements of Tracking System for Radioactive Materials
박 태 순 (주) 덕인, 연구위원
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Contents
1. Introduction
2. Scope
3. Tracking System
4. Transportation of Radioactive Materials
5. Radioactive Materials to be Transported
6. Container
7. Measurement Devices
8. Guardian Devices
9. Control Center
10. Security & Qualification
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Introduction
Radioactive materials are widely used in the industrial non-destructive
testing, medical therapy, and nuclear facilities, etc., and the safety of
radioactive materials are very important to protect threatening to the public
health.
It is required that a tracking system for radioactive materials should be
installed to localize their positions, monitoring their usage, and so on. The
tracking system includes two functions namely a detection of radioactive
materials and wireless communication.
In addition, transport safety and security are vital during all stages of the
nuclear fuel cycle, such as transportation of uranium fuel assemblies,
radioactive waste, spent nuclear fuel.
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Scope
International Standard specifies the requirements of tracking system for
radioactive materials and may also be used for the supplementary guidance
to the regulatory body.
The tracking system consists of a measurement unit and a wireless
communication unit.
- The measurement unit shall include a radiation monitor which measure radiation
dose (or dose-rate), temperature and pressure sensor.
- The wireless communication unit shall include mobile devices, base transceiver
systems and mobile service providers. And it shall localize the position of the
radioactive materials transported using global navigation satellite system (GNSS)
and code division multiple access (CDMA).
Radioactive materials to be tracked include all radioactive material
(radioactive sources, radioactive waste and nuclear material including
nuclear fuel and spent fuel) which is transported using a Type B(U), Type
B(M) or Type C package. And other criteria might be considered when the
transport index is greater than 1.
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Tracking System-1
This system should receive the location information on a real-time basis of
the radioactive materials using a national or regional communication
networks, and should display the exact location in connection with the
related geographical information.
The tracking system shall be fixed at outer surface of the container rigidly
not to detach with the screws provided. The tracking system network
consists of a remote mobile system, the control centre, a mobile service
provider and users.
The remote mobile system consists of a vehicle, a container, a measuring
device, a communication device including position locator, etc. The control
center plays a role of system operation, data and communication servers,
users and location determination service.
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Tracking System-2
Figure 1 – Schematic diagram of tracking system for radioactive materials
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Tracking System-3
Detectors
Radiation detector is used to measure dose/dose-rate or photon energy spectrum
at outside surface of the container which contains radioactive materials. Types of
radiation detector used in tracking system are G-M tube, scintillation detectors,
and semi-conductor detectors. Scintillation and semi-conductor detectors are
also used to measure photon energy spectrum as well as dose/dose-rate. Range
of dose-rate to be measured shall be 0.1 μSv/h to 10 mSv/h.
Sensors
Temperature and pressure sensors are used to monitor environmental conditions
outside the container which contains radioactive materials. Measurement range
of the temperature sensor shall be -20 ℃ to 85 ℃.
Local data storage
Data acquired from radiation detector, temperature sensor, pressure sensor, and
other sensors are stored in local data storage for data security and sent to
control center, simultaneously.
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Tracking System-4
Data acquisition
- The power supplies for radiation detectors and sensors shall be a part of the
tracking system and provided by the manufacturer.
- The radiation, temperature, pressure, and position measurements should be
acquired by the tracking system.
Communication
- Interface
The communication shall be capable of interfacing with WiFi, CDMA, GNSS or
RFID and should be a mobile device which transmits raw data and receives
commands from the control center.
- Location determination
Location shall be calculated with position data gathering from wireless devices
and gyroscope. The resolution for the location determination should be within
100 m. A mobile device shall provide to determine its location.
- Control center
The control center should provide systems to support tracking systems and
users.
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Radioactive materials to be transported-1
Sealed radioactive sources
Sealed radioactive sources which are used in the fields of industrial radiography,
industrial irradiation, medical therapy and others should be tracked.
<For example>
- Ir-192 is one of the most widely used sealed sources for non-destructive testing
(NDT) and put inside of a small container, called type B(U) or B(M).
- Co-60 and Ce-137 are used as sealed sources for medical therapy, calibration of
radiation protection instruments, and industrial irradiation.
- Cs-137 together with Am/Be sources are also used in density gauges.
Since the most of these sealed sources mainly emit gamma rays, the photon
detector contained in the tracking system is used to measure radiation dose(dose-
rate) or energy of gamma rays emitted from the sealed source.
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Radioactive materials to be transported-2
Uranium
Uranium (U) is used to produce nuclear energy in nuclear power and research
reactor. In nature, uranium is found as U-238 (992.739 g/kg to 992.752 g/kg), U-235
(7.198 g/kg to 7.202 g/kg), and a very small amount of U-234 (0.050 g/kg to 0.059
g/kg). 235U has the distinction of being the only naturally occurring fissile isotope. 238U is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to
fissile Pu-239 in a nuclear reactor.
Uranium is used as nuclear fuel of power reactor and research reactor. Nuclear
fuel is mostly transported by large containers.
Fissile material
Nuclear fission products are the atomic fragments left after a large atomic nucleus
undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions
by splitting into two smaller nuclei, along with a few neutrons, the release of heat
energy(kinetic energy), and gamma rays. Fissile material usually contained in
spent nuclear fuel shall be transported with fissile material container equipped
with various kind of safety devices.
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Container-1
Sealed radioactive source
A sealed radioactive source is typically placed in a sealed protective metal casing
in a transportable device, known as a projector or camera. The projector is
considered as one of the transport containers, typically type B including B(U) and
B(M) in accordance with IAEA regulation. The measurement devices shall be
attached at the outside of container.
The design and condition of type B container is follows:
- Each package for radioactive contents with activity shall be not greater than 105A2
- The ambient temperature shall be assumed to be 38°C.
- A package shall not have a maximum normal operating pressure in excess of a gauge
pressure of 700 kPa.
- A package shall be designed for an ambient temperature range from -40°C to +38°C.
Note, A1 and A2
A1 shall mean the activity value of special form radioactive material which is listed in Table 2 or derived
in Section IV of IAEA TS-R-1 and is used to determine the activity limits for the requirements of IAEA
TS-R-1. A2 shall mean the activity value of radioactive material, other than special form radioactive
material, which is listed in Table 2 or derived in Section IV of IAEA TS-R-1 and is used to determine the
activity limits for the requirements of IAEA TS-R-1.
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Container-2
Fissile material
Spent fuel is also placed in a sealed protective metal casing in a transportable
device, known as a container of fissile material. The measurement devices shall
be attached at the outside of container.
Maintain sub-criticality during normal and accident conditions of transport; in
particular, the following contingencies shall be considered:
- Leakage of water into or out of packages;
- Loss of efficiency of built-in neutron absorbers or moderators;
- Rearrangement of the contents either within the package or as a result of loss
from the package;
- Reduction of spaces within or between packages;
- Packages becoming immersed in water or buried in snow; and
- Temperature changes.
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Measurement Device-1
Measurement device
- The radioactivity of Ir-192, used as gamma radiography source, is typically 5
TBq, and that of spent fuel is more than several PBq. It may be dangerous for
workers to handle sources, so it should be recognized the existence of the
radioactive material by means of measurement.
- It is known that the radiation influence to normal certified container is
negligible, but unexpected radiation level should be monitored by means of
radiation measurement using a portable device. Measurement device should be
capable of checking the status of radioactive material and its container, and
consists of a sensor and its supporting electronics.
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Measurement Device-1
Sensor
- A radiation sensor should be installed at outside of a container to measure
radioactivity, and may be able to identify nuclides as well as radiation
dose.
- A sensor detecting leakage of radiation should be rigidly attached on or
outside of a container, or it should be a sensor at least to monitor
open/close state of the container.
- The temperature inside the container may be monitored continuously.
- The position detection devices using WiFi, GNSS or RFID shall be installed
at the surface of the container.
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Measurement Device-2
Electronics
- The device should be capable of providing sensor power and measuring
parameters including radioactivity or on/off state of a container, by either using
analogue or digital technology.
- The device shall be supplied its own operating power during transportation.
- The device shall be provided to monitor the measuring parameters and to
calculate this parameter, if required.
- The device should be included a way to monitor the associated sensors’ integrity
and their alarms.
- The device shall be provided the measured or monitored data to a mobile device.
- The device shall be able to withstand the environmental conditions during
transport.
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Guardian Device-1
Mobile device
- The mobile device should meet with protocols of the location determination
service covered with international, national or specific regional wide.
- The mobile device should be able to receive the request of location
determination service to register its information regarding to the global
position, status, container, etc. of the transportation and control commands.
- The mobile device should be installed a tracking function using a cellular
phone, GNSS chip, RFID (radio frequency identification) tag or bar code.
- The mobile device should be able to transmit the information on request from
the location determination service and execute control command received.
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Guardian Device-1
Mobile device
- Location based services may be applied to the configuration of the tracking
system and control center, and may be used to determine the position (or physical
location) of the tracking system.
- The component of position determination shall be composed of a tracking
services, navigation, routing, addressing, network, feature data and data types
such as voice stream, binary data, map or image.
- The data recording device should be available locally in the mobile device and
operating independently from any wireless connection to ensure a complete
logging history.
- Data logging should be provided so that the mobile device is possible to log
information such as:
• authentication and connection attempts,
• maintenance data (battery wear, CPU load, auto-test results, etc.),
• system-specific process data (temperature, pressure, vibration level, etc.).
- These data should be accessible for a cybersecurity audit in case of a suspected
cybersecurity event.
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Guardian Device-2
CCTV
CCTV may be used for recording on the circumstances of transportation, and
send image data to control center, when unwanted event occurs.
Meteorological status
Meteorological information may be revised, periodically.
Power provision for tracking system
- Power supply should be provided to operate a measuring device for at least one
week. The power of a measuring device may be shared with power supply of a
mobile device or a container.
- Any measuring device should be operating at a lower potential voltage. Any
sensor or instrument should be a device of the lowest power consumable.
Battery level of devices running on batteries shall be monitored.
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Control Center-1
System operation
- It should be possible to monitor the characteristics of a radioactive material
and its status.
- It should continuously be traced the location of a remote mobile system, and
should be identified its pathway.
- It should be possible to set the periods of data transfer.
- It should be able to control a remote mobile system, at an emergency.
- It should be provided to service to trace on the location of a radioactive
material.
Database server and data communication server
- Communication server should be capable of receiving status and location
information for mobile devices.
- It should be provided in the database server to log and maintain the
information of GIS and radiation source at a mobile device which attached on
or outside of a container.
- Database server should be capable of providing the information on location
information interfaced with GIS, mobile devices and radiation sources.
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Control Center-2
Operation
- The user should be able to inquire the location of a radioactive material and the
status of a remote mobile system, with an internet.
- The user should be able to access the actual position and status information of
the tracking system as well as the complete history of the transportation
process via remote wireless connection.
Location determination service
- Location determination service should be used with one of mobile service,
internet service, or radio frequency (RF), RFID or hybrid of these technologies.
- Location determination service should be provided such functions as the
request of status information according to mobile device and its GPS
information.
- Location determination service should provide functions such as calculation of
its location, transmit control command to a mobile device and transmit
information according to location of mobile devices to servers in control center.
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Security and Qualification
Security
Physical security
Wireless devices shall be protected by a solid covering or grid in order to prevent
from damage or unauthorized access. Those devices shall be installed to hardly
access from outside.
Data security or cyber security
Tracking system including mobile devices and the control centre should be
planned, designed, implemented and operated in accordance with ISO/IEC 27000-
series, and more specific requirements
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Security and Qualification
Qualification
Measurement device
- A measurement device should withstand vibration, shock, temperature,
humidity and radiation exposure at around its environment.
- Any software in a measurement device should be developed following
software lifecycle.
- Measurement device should be periodically calibrated.
Mobile device
A mobile device should withstand vibration, shock, temperature, humidity
and radiation exposure at around its environment.