Tritium Assay Analysis by PVT Mass Spectrometer

DOE-HDBK-1129-99

The number of moles of each gas component in the container is calculated by

n(Moles of Component) = (m%(component) /100) x n(Total Moles)

The grams of each component can then be calculated using the formula

Grams of Component =(m%(component)/100) x (n(Total Moles)) x (Gram Molecular Weight of

Component)

The following is the process used to determine the number of moles and grams of tritium in the

HT component in a container.

Calculate the total moles of material in the container.

Analyze the sample using a mass spectrometer to determine the mole percent of HT.

Calculate the number of moles of HT in the container.

Calculate the number of grams of HT in the container.

Multiply the moles of HT by to determine the moles of T2 in the HT component.

Multiply the moles of HT by and by the gram molecular weight of tritium to determine the

grams of tritium in the HT component.

In steps 5 and 6, the is used because it is the ratio of the number of tritium atoms in HT to the

number of tritium atoms in T2 (HT/T2 = 1/2).

The percent tritium in the container is the sum of the mole percent of each tritium component

multiplied by the number of moles of tritium per mole of the tritium component. The moles of

tritium per mole of component is equal to the ratio of the number of tritium atoms in the

component chemical formula to the number of tritium atoms in T2; i.e., 2. This can be expressed

as the following formula:

m%(Tritium Per Mole Total)= 2 m%(T2)+ 1 m%(HT) +1 m%(DT)+

4m%(CT4)+ 2w m%(qTw)+ etc.

The moles of tritium in the container are the sum of the moles of tritium contained in each

component in the container. This is calculated using the following equation, which is the ratio of

the tritium atoms in the component chemical formula to the tritium atoms in T2; i.e., 2. In the

formula qTw/T2 this would be w/2, or in HT/T2 this would be1/2.

[(m%(T2)/100) x (T2/T2) x n(Moles Total)] + [(m%(HT)/100) x (HT/T2) x n(Moles

Moles of Tritium =

Total)] + [(m%(DT)/100) x (DT/T2) x n(Moles Total)] + [(m%(CT4)/100) x (CT4/T2) x

n(Moles Total)] + [(m%(qTw)/100) x (qTw/T2) x n(Moles Total)] + ...

where x/T2 is the number of moles of tritium per mole of the tritium component.

Factoring out n(Moles Total)/100 and rearranging, the equation becomes

(Moles of Tritium x 100)/(n(Moles Total)) = (m%(T2)+ m%(HT)x 1/2 + m%(DT) x 1/2 + m%(CT4) x 2 +

m%(qTw) x w/2 + etc.)

= m%(Tritium Per Mole Total)

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