Design of Equipment

DOE-HDBK-1129-99

Phase III, Decontamination and Dismantlement, involved removing hazardous materials such

as PCBs, mercury, and lead, as well as radioactive constituents such as tritium and fission

products. It also involved dismantling equipment and some structures.

Phase IV, Demolition with Explosives, involved the removal and destruction of the facility and

stack.

Phase V, Waste Management, was a continuing process throughout all six phases. It involved

the determination of how much of each contaminant was present at the site and where the

various site contaminants would be disposed.

Phase VI, Green Grass Restoration, restored the site to a usable, visually aesthetic entity.

Detailed characterization was one of the most challenging phases in dealing with tritium, and

required an expert understanding of the behavior of tritium in porous and non-porous materials.

For example, because tritium migrates to the subsurface of porous materials, volumetric

characterization required core boring. This was not well understood initially and early

characterization activities, which involved smear and scabbling techniques or wiping and scraping

the surface of concrete, gave false (low) tritium contamination levels. In some instances, areas that

were smeared clean, began to reveal elevated readings following rain inleakage. In addition,

destructive testing for nonporous material, such as metals, was required to fully characterize

volumetric tritium contamination.

DOE-STD-1120-98, "Integration of Environment, Safety, and Health into Facility Disposition

Activities," provides guidance for integrating and enhancing worker, public and environmental

protection during facility disposition activities.

5.0 DESIGN OF EQUIPMENT

The design requirements for tritium are a function of the tritium form, quantity, concentration,

pressure, and period of storage. High concentrations of tritium gas stored at high pressure (>

2,000 psia) are difficult to contain due to tritium and helium embrittlement of the container

materials. Design of these systems requires careful selection of the materials of construction and

must be designed using expertise in high-pressure tritium containment.

Low concentrations of tritium in gaseous form mixed with other gases at low (< 600 psia) to

medium (600 to 2,000 psia) pressure, regardless of the quantity, do not significantly impact the

strength of the materials they are stored in. As a result, standard designs can be used.

Tritiated water in the form of T2O is somewhat corrosive unless properly stored with an

overpressure of T2 gas. This is due to the suppression of the formation of oxygen in the cover gas

and peroxides in solution. [25] Tritium systems should be designed by persons with tritium

experience.

Low concentrations of HTO (mCi/mL to Ci/mL) recovered from tritium removal systems have

proven to be corrosive when stored in liquid form in metallic containers and have resulted in the

development of significant leaks in containers within days or weeks. Storage of this same water