Best for Disposal Conditions

DOE-HDBK-1129-99

2.5.3.c Best for Disposal Conditions

Disposing of tritium in the form of a liquid waste or gaseous waste is difficult. Generally speaking,

waste tritium is converted to solid form so that the material can be disposed of as a solid low-level

(radioactive) waste, assuming there is no RCRA hazardous component.

Solid (Metal Tritide): It is possible to dispose of gaseous tritium by converting it to a solid metal

tritide. However, the disposal site requires that the metal tritide not be pyrophoric. If it is in

particulate form, the metal tritide must be contained to meet disposal site requirements.

Liquid (T2O): If the waste is in gaseous form, the tritium is normally removed from the gas mixture

and is reused. If the concentration of tritium in the waste gas is too low to make recovery of the

tritium economically worthwhile, the waste gas is sent to an effluent processing system where the

tritium is removed before the gases are released to the environment. The current effluent

processing systems remove tritium from the waste gas by converting it to water. The water is then

solidified on molecular sieve, clay, mixtures of clay and cement, or Stergo superabsorbent

(discussed in Section 8.1.4.b(2)), and is then packaged as solid waste and shipped to the disposal

site.

Gas (T2): Waste disposal sites generally will not accept packages containing pressurized gases or

those in which a potential exists for generating 1.5 atmospheres (absolute) of pressure over time.

3.0 BASIC TRITIUM REGULATORY INFORMATION

Due to its more hazardous profile, most of the regulatory interest in tritium is concerned with the

oxide form. Figure 2-3 pictorially illustrates various concentrations and regulatory set points. The

radiological materials inventory for tritium accounting purposes may not coincide with the

radiological materials inventory for safety analysis report (SAR) purposes, which may not coincide

with the radiological materials inventory for Environmental Impact Statement (EIS) purposes. This

is due to prescribed allowances for excluding various portions of the inventory, as discussed in

Sections 3.1 and 3.3.

3.1 Tritium Accountability

3.1.1 Radiological Materials Inventory

The Atomic Energy Act describes three categories of materials: Byproduct, Source and Special

Nuclear Material (SNM). There are also three categories of nuclear materials described in DOE

Order 5633.3B, "Control and Accountability of Nuclear Materials": SNM, Source and Other. The

order designates that tritium is an "Other" category material and is accountable nuclear material.

Tritium is accountable for DOE down to 0.01 grams. Items that contain tritium quantities of 0.005

grams or greater are rounded to the nearest 0.01 grams and become accountable items. Items

that contain less than 0.005 grams round to zero and are not accountable items. For the purposes

of accountability, the radiological materials inventory of tritium is the sum of the tritium quantities

contained in the accountable items. This sum does not include any items that contain less than