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A Cleanup Machine Using Reverse Osmosis Method to Remove Silica from Boric Acid Tank at Maanshan Nuclear Power Station

Chung-Hsien Liang, Kuo-Hwa Su

Nuclear Technology / Volume 162 / Number 3 / June 2008 / Pages 333-341

Technical Paper / Nuclear Plant Operations and Control /

Silica concentration in the primary coolant of a reactor coolant system of a pressurized water nuclear plant is a considerable operational issue. It also becomes a safety issue if the crud is very significant. To keep its amount to a minimum is the basic requirement for the purpose of zinc injection in the primary system and protection against its deposition on the fuel rod and poor heat transfer on the primary system and piping. A boric acid cleanup machine has been developed, designed, and installed on the base floor at the auxiliary building of the Maanshan power station of Taiwan Power Company. It is located above the boric acid tank (BAT). This machine with reverse osmosis method was used to clean up boric acid of ~62 m3 stored in the BAT. The results show that its performance has excellent efficiency and capability. The silica concentration was reduced to ~0.605 ppm from the original value of ~3.150 ppm. The resulting waste contained ~2.52 wt% of boron depending on the original boron amounts in the BAT. After the cleanup is finished, the concentration of boron in the BAT still maintains its operable and safe operating range of 7000 to 7700 ppm. Finally, the written procedure has been completed in order that the machine will be applied as a routine cleanup system.

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