Half-plant zeta potential test. Final report

With the exception of N Reactor, the production reactors operated by Douglas United Nuclear, Inc., use treated Columbia River water as the coolant on a once-through basis. Thus, radionuclides formed largely by the neutron activation of river salts are discharged to the river. One method of reducing the quantity of radionuclides in the effluent is to increase the efficiency of parent isotope removal during the coolant treatment process. Prior to 1961 the water treatment process had been improved to the point that reactor quality coolant could be produced using an average alum flocculent feed rate of 6 ppm. Laboratory experiments carried out in 1959 and 1960 demonstrated that a markedly increased removal of parent isotopes resulted when alum feed rates in the neighborhood of 20 ppm were used. Flocculant feed rate control based on producing a constant value of the electrokinetic charge (zeta potential) of the floc has been practiced at some water treatment plants. Although the hypothesis has not had universal acceptance in the water treatment field, laboratory and field data accumulated at Hanford indicated that further evaluation of the approach was warranted. In order to determine the effects of coagulant control based on zeta potential a half-reactor test was initiated at C Reactor on September 1, 1966. The data obtained during the first seven months of the test have been summarized previously. The test was terminated August 31, 1967, and it is the purpose of this report to present the results of the test