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Friday, March 11, 2016

InduSoft Web Studio Aids in Nuclear Material Containment

Thermal Tests on Transportation of Irradiated Fuel Automated with InduSoft Web Studio


  • The Nuclear Technology Development Centre in Brazil developed a half-scale model of a planned nuclear material transportation unit designed to meet the transportation criteria established by the IAEA for Type B packages carrying fissile materials.

  • To successfully complete the tests to IEAE specifications, the Centre developed a SCADA system using InduSoft Web Studio to automate and record the results of thermal testing.

  • As a result of successful testing protocols, the Center will be able to investigate the value of building a full-scale containment and transportation unit for safe handling of nuclear materials.

Figure 1: The system records the results of numerous tests, including thermal exposure, submersion, and impact resistance.


 

The future of energy worldwide may soon turn toward nuclear energy as the best source of low-carbon fuel. However, the dangers of handling and controlling nuclear energy have necessitated strict regulations. Institutions that wish to develop and study nuclear technology must test new methods of handling nuclear materials under a set of rigorous IAEA (International Atomic Energy Agency) regulations.
 
When the Nuclear Technology Development Centre/Brazilian Nuclear Energy Commission designed a container for the transport of irradiated fuel for nuclear research facilities, they had to put the containment unit through a series of strictly controlled tests – chief among them, thermal tests designed to measure whether the containment unit could withstand the heat of a sustained fire that generates a temperature of 800 degrees Celsius for 30 minutes or more.



Figure 2: The thermal test consisted of submitting the model to 30 minutes to a temperature of 800 degrees Celsius.

The Challenge

The Nuclear Technology Development Centre developed a half-scale model of a planned nuclear material transportation unit. The unit was designed to meet the transportation criteria established by the IAEA for Type B packages carrying fissile materials. Therefore, the containment unit had to be sturdy enough to resist possible transport accidents, including a free drop from 9 meters on a rigid surface, a one-meter drop onto a flat pin, a fire that generates a temperature of 800 degrees Celsius for 30 minutes, and submersion to 15 m depth of water.
 
The transportation unit’s components include the main body, lids, fuel basket, shock absorbers and connection bars. The body consists of a sturdy cylindrical structure with an internal cavity to accommodate the basket that holds the spent fuel elements. Its bottom and sidewall are sandwich-like shielded barriers consisting of stainless steel outer and inner surfaces and lead in-between. Four lifting trunnions exist on the package sidewall to allow its vertical handling and rotation. A draining port, equipped with quick-connect valve and protection lid is located at the side of the package, close to its bottom rim.
 
The unit has a double lid system. The internal lid is also a stainless steel structure with lead filling; an access – similar to the draining port – is embedded to the lid, providing access to the internal cavity for gas pressurization, sampling and purging. The internal lid is part of the package’s containment system and is, therefore, provided with a double metallic sealing system. An access point to the annular space between the sealing gaskets is provided as a testing point of the package’s cavity containment. The internal lid is attached to the package’s main body by 24 bolts.
 
The external lid is made of stainless steel and has a circumferential groove to accommodate an elastomeric gasket, its main function being the protection of the internal lid. The external lid is fixed to the main body by means of sixteen bolts.

The internal basket is removable and consists of a structure of 21 square tubes, horizontal connection plates, side and bottom plates and foot supports.
 
For protection against mechanical and thermal loads, the transportation unit includes top and bottom external removable impact limiters. These are structures made of external stainless steel skin and rigid polyurethane foam filling for shock energy absorption and thermal protection. The foam density is 165 kg/m3 and, for enhanced thermal protection, fire retardant is added to its composition.

As part of the package development program, a half-scale model was submitted to the sequence of tests prescribed at the IAEA´s standard for the safe transport of radioactive material. The thermal test was carried out as part of the sequence of tests aimed at creating comparable hypothetical accident conditions to which a package could be submitted to during transportation.
 
The test consisted of submitting the model to 30 minutes to a temperature of 800 degrees Celsius. The test was carried out in an industrial electrical furnace preheated to 810 degrees, and the model was equipped with temperature indicating labels and thermocouples. The labels were installed in different positions inside the package cavity, including the cavity walls, basket and dummy fuel elements. The thermocouples were mounted in the following positions: two inside holes existing on the external lid; two inside the package cavity and two inserted into especially designed passages through the package body wall (one inserted 1/3 deep on the wall thickness and one 2/3 deep on the wall thickness). The two last sensors were meant to record the temperatures of the lead during the test.

To successfully complete the tests to IEAE specifications, the Nuclear Technology Development Centre had to develop a supervisory SCADA system designed to take accurate records of the results of each heat test so they could be presented to the IEAE. A dedicated data acquisition system was developed using InduSoft Web Studio to automate and record the results of thermal testing.
 
An advantage of using InduSoft Web Studio was its flexibility and the low cost associated with using InduSoft Web Studio to measure other process variables as needs arose.  Instead of purchasing new software for each new test, the Center could instead add screens or additional sensor data to the InduSoft Web Studio application.

 

The Solution

The system developed for temperature acquisition of the thermal test allows real time indication and graphical plotting of the process trend data collected during the test. The temperature sensors used are Type K thermocouples with mineral isolation, manufactured by ECIL. The thermo-element dimensions are 5,000 mm length by 6 mm diameter.

The signals captured by the thermocouples are initially inserted into a remote board for conversion from analog to digital signals. During the runtime, the signal characteristics are parameterized by auxiliary software. The signal is converted from the communication protocol RS-485 to RS-232 – the protocol used by the computer serial board. The signal is finally loaded into the InduSoft Web Studio system directly on the computer serial port or on the USB port using a serial/USB convertor.

 

Figure 3: The test results are automatically recorded. The system records all tests, and tests that did not pass certification standards.

The signal, parameterized in the communication ports, reaches the InduSoft Web Studio system and the process temperatures are displayed in the virtual instrumentation and plotted in real time in process trend graphs.

The integrated system consists of both the electronic panel connected to the sensors and the software application. The latter is developed in the InduSoft Web Studio development environment, where the application appearance is configured. The virtual instrumentation and the trend graphs and variable values are displayed on the main screen.

 

The Results

The InduSoft Web Studio system is a flexible and reliable platform for industrial and research applications where the collection and storage of data relayed by sensors is necessary.

This system was easy to develop from scratch, and easily added to later in order to include new features and new parameters for testing. New features can be incorporated simply by adding new screens, which translates into less investment of resources for the acquisition of new equipment.

The InduSoft Web Studio application enables the operators to remotely follow the process behavior if the computers are online via an adequate communication protocol.

As a result of successful testing protocols, the Center will be able to investigate the value of building a full-scale containment and transportation unit for safe handling of nuclear materials.



Figure 4: The application records all test results in a database for report generation.


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