Chemical Processing cont'd

DOE-HDBK-1132-99

material should recognize the corrosive nature of process solutions.

Design of tankage should recognize the potential for post-precipitation

and formation of a layer of solid precipitate on the bottom of the tank.

Care should be exercised in agitating such a layer if it forms because a

nuclear criticality could occur. Hence, tankage with small horizontal

surfaces, such as hollow cylindrical tanks, is desirable.

Piping and valves should be located so that flammable, explosive, or toxic

gases or liquids that are necessary to the process can be isolated to

prevent injuring workers if an accidental release occurs. The flammable

gases should be provided by a hard-piped system with the gas supply

located outside the facility in cylinders to limit the total quantity available

in the event of a fire or explosion.

Radioactive liquid piping systems should be designed to avoid notches,

crevices, and rough surfaces that might retain radioactive material. The

piping system that collects contaminated liquids should be designed so

that effluents from leaks in the system can be collected without releasing

the liquids into the personnel access areas or to the environment.

Stainless steel should be used in radioactive waste and process system

piping and equipment so that smooth, nonporous, corrosion-resistant

materials are in contact with the contaminated, corrosive, and radioactive

liquids. The piping system should be of welded construction whenever

practicable. Flanges should be used only when absolutely necessary for

servicing.

Piping or other conduits to convey plutonium solutions or plutonium-

contaminated waste liquid should be double-walled or contained within an

enclosure provided with a leak-tight barrier. Any potential leakage from

the primary pipe should be collected in a geometrically safe sump or tank.

Wherever possible, the piping system should be designed to avoid traps

that could hold plutonium solutions.

I-53