Requirements - std60030064

DOE-STD-6003-96

f. prevent unwanted buildup of tritium within a facility; and

g. protect and control tritium commensurate with its monetary value.

It is difficult to determine the distribution and precise inventory of tritium in a fusion facility.

Usually, measurement before injection into the plasma chamber and after removal from the

plasma chamber is possible (referred to as inventory by difference). However, tritium production

in the machine is also possible. Therefore, the actual amount of tritium remaining in the machine

is difficult to determine (this can affect the safety analysis, because there is usually an upper

bound on the amount of tritium allowed in the vessel). Sampling tiles or protective surfaces

maybe a way of determining the tritium levels; however, those samples may or may not be

representative of the tritium levels throughout the vacuum vessel.

It is therefore critical that the designers of the facility determine appropriate means to

reliably measure tritium in the fusion facility. This should be done early in the design process to

minimize tritium holdup, allow for pumping and purging systems to evacuate the tritium, and

specify appropriate instrumentation for measurement. These actions will assure safety of the

facility, reduce the risk of a release and improve worker safety. Methods for measurement of

tritium are specified in later paragraphs.

Tritium is the predominant nuclear material used at fusion facilities. It is of interest

because of safety concerns, its monetary value, and possible unauthorized diversion for other

applications. Although public exposures and environmental releases are expected to be small

and well below regulatory limits from a fusion facility, tritium is a radioactive material, and the

public will need to be assured that safety has not been compromised.

Other nuclear material that must be controlled and accounted for at fusion facilities

includes depleted uranium (U-238) and deuterium. Depleted uranium is used for storage of

tritium, fission chambers, and various radioactive check- and calibration-sources. Deuterium in

quantities greater than 100 g is also controlled at DOE facilities (DOE Order 5633.3B and

5660.1B). The control and accountability of these materials is relatively straightforward and does

not present significant problems for operating facilities. The scope and extent of the

accountability program for these materials should be based on the monetary value of the

material and should include inventories and some measurements.

4.4.8.1 Requirements

The requirements placed on the control and accountability of tritium fall into three cate-

gories. Those required by the U.S. law, those required by DOE Orders, and those required by

"good practices." It is also important to note that requirements are not consistent throughout the

international community.

a. Legal requirements. The legal requirements on tritium measurement are as follows:

1. Environmental facility emissions, which include air emissions and releases to the

ground water or at facilities outfalls, are regulated. These include federal and state