Liquid waste processing system

Freeman, J., Wolf Creek s liquid waste processing system improvements, in Proc. EPRI Int. Low-Level Waste Conf. 2000, Electric Power Research Institute, Palo Alto, CA, 2001. 

The liquid waste processing system is provided for use in the processing and handling of radioactive wastes generated during various modes of plant operation. The system is designed to receive, segregate, process, monitor, and recycle for reuse all primary... 

Since the SMART does not use soluble boron in the primary coolant, the total amount of liquid waste generation would be minimized. This feature simplifies the liquid waste processing system. 

Anywhere spent nuclear liiel is handled, there is a chance that iodine-129 and iodine-131 will escape into the environment. Nuclear fuel reprocessing plants dissolve the spent fuel rods in strong acids to recover plutonium and other valuable materials. In the process, they also release iodine-129 and -131 into the airborne, liquid, and solid waste processing systems. In the U.S., spent nuclear fuel is no longer reprocessed, becau.se of concerns about nuclear weapons proliferation. 

AR477 3.10 Liquid waste treatment system design guide for plutonium processing and fuel fabrication... 

The liquid waste treatment system collects, processes and monitors all potentially radioactive liquid waste produced during normal plant operation and maintenance. The liquid effluent is discharged, reused or finally disposed in the plant according to its radioactive level. 

Scrub solutions used for off-gas cooling or cleanup, together with all condensates and purge streams, should be collected, treated and returned to the scrubbing process. There shall be no direct pathway for active liquids to the environment. The scrub solution system blowdown should be treated by a radioactive liquid waste treatment system. In some instances the blowdown may be processed (e.g. dried) in the incineration system. 

In LWRs, before treatment some of the hquid wastes may have a radionuclide content as high as that of the reactor coolant, with the exception of short lived nuclides, which will have decayed, and gases, which will have been evolved as a result of depressurization. Concentrations of up to a few 10 Bq/ m may be found in such untreated liquids. Thus, since the liquid waste treatment system processes active liquids, radioactive substances will... 

Initially the nickel-chromium plating process is designed to minimize the liquid loading to the waste treatment system. Counterflow rinsing, spray rinsing, and stagnant rinse recovery methods are employed in order to minimize the amount of wastes to be treated and allow as much treatment or retention time in the waste treatment system as is possible. 

Upflow expanded bed carbon columns are a third contacting process. The liquid waste enters the bottom of the carbon column and expands the carbon bed. Higher suspended solids concentrations can be handled in this system because of the greater distance between particles in an expanded bed. 

Biological toxicity tests are widely used for evaluating the toxicants contained in the waste. Most toxicity bioassays have been developed for liquid waste. Applications of bioassays in wastewater treatment plants fall into four categories [19]. The first category involves the use of bioassays to monitor the toxicity of wastewaters at various points in the collection system, the major goal being the protection of biological treatment processes from toxicant action. 

Mixed fertilizer (subcategory G) treatment technology consists of a closed-loop contaminated water system, which includes a retention pond to settle suspended solids. The water is then recycled back to the system. There are no liquid waste streams associated with the blend fertilizer (subcategory G) process, except when liquid air scrubbers are used to prevent air pollution. Dry removals of air pollutants prevent a wastewater stream from being formed. 

The electric infrared incineration technology is a mobile thermal processing system that is suitable for soils or sediments contaminated with organic compounds, polychlorinated biphenyls (PCBs), and metals. Liquid organic wastes can be treated after mixing with sand or soil. Electrically powered silicon carbide rods heat organic wastes to combustion temperature while any remaining combustibles are incinerated in an afterburner. 

System 1 is based on MC8 (0.065 M) but needs the addition of TBP (1.5 M) in the organic phase and the introduction of oxalic acid in the liquid waste to prevent the extraction of zirconium by TBP. It has been pointed out that the addition of oxalic acid is necessary for the PALADIN process, previously implemented for the extraction of minor actinides. The addition of TBP which extracts several cations, leads to a lesser selectivity of the solvent. 

The sequence of process steps shown in Fig. 4 produces three batches of spent resin (a total of about 4 L) and introduces about 50 kg of LiCl into the liquid waste system. The initial product recovery steps require about two weeks of operating time, and the clean rework recovery requires another 2 weeks. 

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