Tritium Concentration Measurement.

DOE-HDBK-6004-99

specific application. For example solid tritium storage beds that can be disconnected and moved have

been placed in a calorimeter designed to accept the bed.

New methods are being developed to allow for the determination of the amount of tritium stored on

a solid storage bed. When tritium is stored on uranium bed the temperature increase of the bed can

be used to determine the amount of tritium stored on the bed. When tritium is stored on a material

such as LaAlNi, usually gas is passed through the secondary containment to maintain the temperature.

The temperature rise of the gas as it passes through the bed can then be used to determine the amount

of tritium. Both of these methods are being proposed for tritium accountability. Their acceptance

is now based on a case by case system and they are not used widely.

Development of these methods will be important for the operation of fusion facilities. They offer

potential savings in time and effort to account for the tritium in a facility.

Tritium Concentration Measurement.

A beta scintillation counter has been used for tritium measurement if only the total tritium

composition is required. In this instrument, the gas is passed over a crystal that will scintillate with

the beta from the tritium decay. A photomultipier tube is used to detect the light. The tritium

concentration can then be determined from the signal from the photomultipier tube. This method is

commonly used for gas inventory requirements.

Liquid scintillation is commonly used to determine small concentrations of tritium. The tritium liquid

or compounds containing tritium are placed in a scintillation liquid. The liquid is then placed in a

counter which determines the amount of tritium by the light emitted from the sample.

Ion chambers are commonly used to determine environmental tritium releases and to monitor the

atmosphere for personnel safety. Process ion chambers are used for determining tritium

concentrations in secondary containment. Specially designed ion chambers can be used to determine

high concentrations of tritium.

Ion chambers will measure any radioactive material which can cause ion pairs. They are also

susceptible to contamination from materials which adsorb on surfaces and can only be used for gas.

Facility Measurement Recommendations.

Measurement of tritium input / output to facility

The primary method used historically for the measurements of tritium shipments has been pressure

/ volume / temperature/ composition (PVTC) measurement with the composition determined by either

a mass spectrometer or beta scintillation counter.

Calorimeter can be used for the measurement of tritium absorbed on solid storage beds that are

designed to be used as primary shipping containers and also be placed in the calorimeter.