High-Level Liquid Waste Confinement

DOE-HDBK-1132-99

associated cooling system. Agitation of tank contents should be

provided, when necessary, to control waste temperature.

Double-walled piping, multi-pipe encasements, and double-walled tanks

should be considered to establish the primary and secondary

confinement boundaries in underground portions of high-level liquid

waste systems. Provisions should be made to detect leakage from the

primary confinement to the interspace.

Installation of spare pipelines between transfer points should be

considered.

Process and waste storage vessels should be vented through appropriate

treatment systems that control the release of radioactive material in gaseous

effluents, ensuring these releases are ALARA. Design of these systems

should consider the following:

Off-gas should be suitably pretreated upstream of off-gas treatment

equipment to remove or reduce the concentration of chemicals that may

adversely affect system operation.

The venting system should prevent overpressure or vacuum conditions

from occurring within vessels.

The venting system should prevent the build-up of hydrogen from

radiolysis.

Tank overflows should be directed to collection systems.

Integrity of the primary confinement boundary should be determined by some

or all of the following measures:

vessel inventory monitoring (e.g., liquid level sensors);

on-line leakage monitoring for the interspace of double-walled vessels

(e.g., airborne activity monitors, sump level sensors, conductivity cells);

I-79