Early construction and operation of highly contaminated water treatment system in Fukushima Daiichi Nuclear Power Station (I) – Ion exchange properties of KURION herschelite in simulating contaminated water

Abstract

To support the design and operation of the decontamination system using KURION media for the treatment of highly contaminated water accumulated in Fukushima Daiichi Nuclear Power Station, Central Research Institute of Electric Power Industry has urgently carried out many kinds of research and development programs to support the operation of the decontamination system using columns filled with three kinds of KURION media (H, AGH and SMZ). Since the contaminated water at Fukushima Daiichi Nuclear Power Station contained seawater and oil, the effects of sea salt and dissolved oil on Cs adsorption behavior were examined closely by batch type. The concentration of sea salt in the solutions was varied between 0.0 and 3.4 wt%. The Cs adsorption capacity of KURION herschelite in seawater decreased to nearly 1/10th of that in pure water, but it was still concluded that herschelite has sufficient adsorption capacity to remove Cs from the contaminated water. The effect of dissolved oil could be ignored because of its low solubility in seawater. Langmuir-type adsorption isotherm equations, which can be applied for estimating Cs adsorption in sea salt containing water, were developed.

Early construction and operation of the highly contaminated water treatment system in Fukushima Daiichi Nuclear Power Station (II) – dynamic characteristics of KURION media for Cs removal in simulated contaminated water

“…Also, the adsorbed amount of Cs in the herschelite column decreased from 1.4 × 10 −2 to 4.2 × 10 −3 mmol/g at approximately 1000 bed volumes with an increase in the sea salt ratio in the feed solution from 1.0 wt% (A-2) to 3.4 wt% (A-5). These results suggest that the adsorption of Cs is hampered by the sea salt ratio, as expected from the equilibrium ion-exchange isotherms obtained for KURION-herschelite in sea salt of different concentrations [17].…”

“…It was reported that Kd (distribution coefficients) of Cs was increased with an increase of V/M, when Cs in the solution was adsorbed with the zeolite [18]. When the isothermal of Cs adsorption was similarly measured in the batch equilibrium test of pure water [17], the adsorbed amount of Cs at V/M = 1000 became larger than that at V/M = 100 as shown Figure 5. However, the adsorbed amount of Cs at V/M=1000 was in almost agreement with that at V/M = 100 in 3.4 wt% sea salt ratio, so the effect of Cs adsorption of V/M was smaller than that in pure water.…”

“…The adsorbed amount of Cs in the herschelite column was estimated to be about 1.3 mmol/g at 25,180 bed volumes in the case of 0 wt% sea salt ratio even though the column did not attain the perfect breakthrough point in run A-1. When the relative concentration of Cs was 0.2 in run A-1, the adsorbed amount of Cs in the column test (A-1) was about 1.4 times larger than that in the batch equilibrium test (V (solution volume)/M (weight of adsorbent) = 100) [17], as shown in Table 4. It was reported that Kd (distribution coefficients) of Cs was increased with an increase of V/M, when Cs in the solution was adsorbed with the zeolite [18].…”

“…(3) at total bed volume. * * These values were calculated from the Langmuir equation [17]. * * * These values were the ratio of the adsorbed amount in C 0 to that in 0.57 ppm.…”

Early construction and operation of the highly contaminated water treatment system in Fukushima Daiichi Nuclear Power Station (IV) - Assessment of hydrogen behavior in stored Cs adsorption vessel

“…The core of the system is the vessels filled with zeolite media which adsorbs the Cs in the contaminated water. Just after the accident, Central Research Institute of Electric Power Industry has started various technical supports [1][2][3][4] for Tokyo Electric Power Company to establish the system smoothly and to operate the system safely and stably. The study reported in this article, conducted from June to August in 2011, is about an assessment on the behavior of hydrogen in the used zeolite vessels stored in the same site.…”