Example 2Facility name: Comanche Peak nuclear power plant (USA) Membrane system: Ultrafiltration and reverse osmosisObjectives: — Demonstrate removal of activity, in particularcolloidal 58Co— Remove caesium and iodine to non-detectable levels— Evaluate reverse osmosis as a viable processing option for reduction of secondary waste volume (e.g. spent ion exchange resin) The Comanche Peak nuclear power plant is a two unit PWR plant with each unit rated at 1150 MW(e). Prior to evaluating advanced ultrafiltration/ reverse osmosis technology, the plant used a filter and demineralizer system to process all liquid waste prior to discharge. A 38 L/min (10 gal/min) pilot ultra- filtration/reverse osmosis/demin unit supplied by RWE NUKEM was installed in parallel with the original process so that a side-by-side comparison could be made while each waste stream was being processed [96, 97].The objectives of the pilot unit tests at Comanche Peak were to:(a) Demonstrate the removal of activity, colloidal 58Co in particular, to below discharge limits of 1 × 10–05 mCi/mL;1(b) Remove caesium and iodine to non-detectable levels;(c) Evaluate reverse osmosis as a viable processing option for reduction of secondary waste volume, i.e. spent ion exchange resin;(d) Determine the volume reduction achievable by reverse osmosis.Floor drain water, resin sluice water and boron recycle system water were processed during the testing. Total suspended solids were first removed from the feed by an ultrafiltration unit, and dissolved contaminants were then removed from the ultrafiltration permeate by reverse osmosis. The reverse osmosis unit was single-pass and had an internal recycle of the reject stream. Specific reverse osmosis (nanofiltration) membranes were used for passage of boron. Cation and anion resins were used to polish the reverse osmosis permeate before discharge to a plant product water collection tank. Both the ultrafiltration and reverse osmosis rejects were returned to the floor drain.The results of the pilot testing at Comanche Peak are summarized below. Table 11 shows a comparison of DF of the plant filter/demin system and the alternative ultrafiltration/reverse osmosis/demin unit that was tested.
Other results were as follows:
(1) The ultrafiltration/reverse osmosis technology, when used with deminer- alizers, performed better than the demineralizer technology currently used at Comanche Peak.
(2) Product water was immediately and consistently below activity discharge limits.
(3) The ultrafiltration/reverse osmosis technology produced 151 m3
(40 000 Gal (US)) of clean water and generated approximately 151 L (40 Gal (US)) of reject, with a CF of 1000.
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