TN699 – Adaptation of standard thermal analyzers and calorimeters to nuclear environments

INTRODUCTION

Radioactive materials science requires handling of hazardous substances (fuels, wastes, reactive gases, etc) under safe conditions for the operators and characterization instruments. In a lot of cases, these materials need to be handled in glove boxes or in hot cells (lead chamber) depending on the radiations types and intensities.

Thermal analysis and calorimetry are common thermal characterization techniques for nuclear fuels (current or candidates), wastes, and surrounding materials (ex: cladding). It means that the instruments concerned must be customized to become compatible with these specific operating conditions.

 

KEY ELEMENTS

Our skills in customized instrument design, our expertise in electronics, and the organization of our R&D service being structured to manage specific projects have been applied for a long time in such cases.

The major issue is to separate the thermal analyzer elements such as furnace, sample chamber and containers, measuring modules, etc that must be placed in the glove box or hot cell, from the control and acquisition electronics. These are preferably kept outside the glove box or hot cell because of their low resistance to irradiation and in order to ease the instrument maintenance.

Once designed and manufactured, the unit also needs to be installed by our qualified personnel, accredited to operate in nuclear environments.

 

TECHNICAL ACHIEVEMENTS

High temperature TGA, TG-DTA/DSC (for corrosion, stability, Stoichiometric studies, long-duration isothermal reactivity of oxides), high temperature calorimeters (drop or heat flow methods for heat capacity and phase diagram determinations) or lower temperature Calvet calorimeters (for thermal activity of wastes, heats of reaction) have already been successfully customized to fit these specific conditions. See the pictures below.

 

DSC131evo labsys tga glovebox

DSC131 Evo: the electronic circuitry (left) is installed in a separate remote box avoid its exposition to radiations.

“Customized” LABSYS TGA to be placed in a glovebox

High temperature calorimeter placed in a glovebox (reproduced from [1])

 

GOING FURTHER

There are application fields outside the nuclear activities for these customized instruments. For instance, when toxic materials are tested, flammable or explosive gases are involved or when a contact with air may affects the integrity of the tested material .

 

In a few cases, the instruments need to be deeply redesigned to be implemented in existing glove boxes or hot cells and assembled inside by operators guided by our engineers and technicians.

 

CONTEXT

A widely renowned institute in the field of nuclear research consulted SETARAM Instrumentation to design, manufacture and deliver a thermobalance to be inserted in an existing glovebox. It was part of a glovebox chain dedicated to the preparation and characterization of actinide based samples.

The inside dimensions were of course fixed. But because it was not possible to open the glovebox, the assembly of all the thermobalance parts also had to be done on site by operators guided by our engineers and technicians. Moreover, all of the parts had to be transferred thanks to containers of challenging maximum dimensions (diameter 250mm and height 380-800mm) and maximum loading capacities (5 or 25kg depending on the container).

Other more common constraints were also related to the thermobalance maximum outside temperature (no part above 50°C), the separation of the electronic circuitry, and the use of the thermobalance on an earthquake resistant chassis.

A number of controls from the client were scheduled during the design and manufacturing process, with factory acceptance and on-site acceptance tests.

 

TECHNICAL ACHIEVEMENTS

The electronic circuitry was installed in a separate box connected to the thermobalance by cable feedthrough. It allowed saving space in the glovebox and decreasing the amount of irradiated wastes.

All of the bulky parts were redesigned, including the thermobalance platform and furnace power supply transformer in order to fit the dimensions of the transfer container. The thermobalance was placed on an articulated chassis in order to access to any part of the instrument, and a number of mounting parts have been redesigned: handles were added to ease the operation of the different heavy or bulky parts, the ease of maintenance of the balance was improved… Moreover, sharp or cutting parts were modified to avoid any risk of spoiling the gloves.

The furnace cooling was changed to a double loop system with a primary circuit and a heat exchanger inside the glovebox, and a secondary circuit outside the glovebox with quick fit connections.

 

cad

CAD schematics (left) and

thermobalance installed in the glovebox (right)

glovebox2