Materials in the Gaseous State

DOE-HDBK-3010-94

2 .0 M A T E R IA L S IN T H E G A S E O U S S T A T E

2.1

N O N C O N D E N S I B LE G A S E S

2.1.1

S u m m ary of A n alysis of D ata

Loss of Physical Containment. For noncondensible gases, the recommended

ARF is 1.0. All materials in the gaseous state can be transported and inhaled;

therefore, a value for RF of 1.0 is assumed for the purposes of these analyses.

2.1.2

D iscu ssion

In DOE nonreactor nuclear facilities, radionuclides in the form of noncondensible gases are

only found under a few circumstances: as stored tritium, encased in a stored spent fuel

matrix, generated by physical or chemical reaction, and generated by inadvertent nuclear

criticalities (see Chapter 6). The radiological impact on the human body varies greatly

between radionuclides. The noble gases (krypton, xenon) primarily expose the individual to

an immersion dose during the passage of the cloud of gases. Their impact, in terms of total

effective dose equivalent (TEDE), is from 5 to 10 orders of magnitude less than for the same

level of activity of 239Pu or other actinides as particles in the respirable size fraction.

However, the noble gas dose will be prompt as opposed to the fifty-year cumulative dose

associated with alpha-emitting actinides. Accordingly, such gases may represent a greater

threat for acute health effects than the higher specific activity alpha-emitting actinides.

The most significant gaseous radionuclide handled outside of cladding matrices is tritium.

Tritium is a special case where factors in addition to ARFs and RFs are especially

significant. These other factors are the form of the tritium (i.e., elemental tritium or tritium

oxidized to a molecular form), which significantly affects the potential dose from exposure,

and the exposure modes, which include transpiration. These other factors relevant to tritium

are not addressed in this document.

Page 2-1