Mark S. Denton

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

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.

Characterization and storage of radioactive zeolite waste

For the safe storage of zeolite wastes generated by the treatment of radioactive saline water at the Fukushima Daiichi Nuclear Power Station, this study investigated the fundamental properties of herschelite adsorbent and evaluated its adsorption vessel for hydrogen production and corrosion. The hydrogen produced by the herschelite sample is oxidized by radicals as it diffuses to the water surface and thus depends on the samples water level and dissolved species. The hydrogen production rate of herschelite submerged in seawater or pure water may be evaluated by accounting for the water depth. From the obtained fundamental properties, the hydrogen concentration of a reference vessel (decay heat = 504 W) with or without residual pure water was evaluated by thermal–hydraulic analysis. The maximum hydrogen concentration was below the lower explosive limit (4%). The steady-state corrosion potential of a stainless steel 316L increased with the absorbed dose rate, but the increase was repressed in the presence of herschelite. The temperature and absorbed dose at the bottom of the 504 W vessel were determined as 60 °C and 750 Gy/h, respectively. Under these conditions, localized corrosion of a herschelite-contacted 316L vessel would not immediately occur at Cl− concentrations of 20,000 ppm.

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

The kinetic characteristics of the column were necessary property to be understood before actual operation. Hence, a functional small-scale zeolite column system was installed for conducting the experiments to understand decontamination behaviors. Each column has a 2 cm inner diameter and a 12 cm height, and 12 g of zeolite-type media was packed into the column. The column experiments were carried out with Kurion-zeolite, herschelite, at different feed rates of simulated water with different concentrations of Cs and sea salt. As expected from equilibrium ion-exchange isotherms obtained for KURION-herschelite, the adsorption of Cs is hampered by the existence of sea salt ratio. The difference in breakthrough behaviors can be ascribed to the difference in sea salt ratio. Above 1000 bed volumes, the adsorption rate of Cs was the same at a solution velocity of between 14 and 81 cm/min. Under the condition of a 3.4 wt% sea salt ratio, the performance of the media supplied by KURION was in the order surfactant modified zeolite < silver-impregnated engineered herschelite = herschelite (H). This result was suggested to evaluate the performance of KURION media on the actual columns.

CSA continuous countercurrent ion exchange (CCIX) technology

Abstract The CSA-CCIX concept started at ORNL in 1951. It has been adapted to a wide variety of applications worldwide, in water and waste water treatment, fertilizers, hydrometallurgy, and general chemical processing. Unique features and how it works are described. Two extreme applications are described in detail. One is for the extraction of trace amounts of uranium from a copper leach, at 37.85m3/min (10,000 gpm) where very high throughput rates are emphasized. The other is for Acid Retardation, where a strong acid waste is purified and recovered. The feed processing rate here is much lower than the resin rate.

Fukushima Two Year Processing Update

On March 11, 2011, now two years ago, the magnitude 9.0 Great East Japan earth quake, Tohoku, hit off the Fukushima coast of Japan. This was one of the most powerful earthquakes in recorded history and the most powerful one known to have hit Japan. The ensuing tsunami devastated a huge area resulting in some 25,000 persons confirmed dead or missing. The perfect storm was complete when the tsunami then found the four-reactor, Fukushima-Daiichi Nuclear Station directly in its destructive path.Some 2 million people were evacuated from a fifty mile radius of the area and evaluation and cleanup began. A tremendous effort has been made, by many nationalities, since this time to restore this damaged plant and surrounding area and to return a great deal of the residents to their homes and farm lands.While most of the outcome of this unprecedented natural and manmade disaster was negative, both in Japan and worldwide, there have been some extremely valuable lessons learned and new emergency recovery technologies and systems developed to cope with the aftermath of this disaster.This paper describes new technology developed to selectively remove radioactive materials dangerous to workers, local citizens, and the natural environment from seawater used to cool the damaged reactors at Fukushima.As always, the mother of invention is necessity.Copyright

Innovative Highly Selective Removal of Cesium and Strontium Utilizing a Newly Developed Class of Inorganic Ion Specific Media

Highly selective removal of Cesium and Strontium is critical for waste treatment and environmental remediation. Cesium-137 is a beta-gamma emitter and Strontium-90 is a beta emitter with respective half-lives of 30 and 29 years. Both elements are present at many nuclear sites. Cesium and Strontium can be found in wastewaters at Washington State’s Hanford Site, as well as in wastestreams of many Magnox reactor sites. Cesium and Strontium are found in the Reactor Coolant System of light water reactors at nuclear power plants. Both elements are also found in spent nuclear fuel and in high-level waste (HLW) at DOE sites. Cesium and Strontium are further major contributors to the activity and the heat load. Therefore, technologies to extract Cesium and Strontium are critical for environmental remediation waste treatment and dose minimization. Radionuclides such as Cesium-137 and Strontium-90 are key drivers of liquid waste classification at light water reactors and within the DOE tank farm complexes. The treatment, storage, and disposal of these wastes represents a major cost for nuclear power plant operators, and comprises one of the most challenging technology-driven projects for the DOE Environmental Management (EM) program. Extraction technologies to remove Cesium and Strontium have been an active field of research. Four notable extraction technologies have been developed so far for HLW: solvent extraction, prussian blue, crystalline silicotitanate (CST) and organic ion-exchangers (e.g., resorcinol formaldehyde and SuperLig). The use of one technology over another depends on the specific application. For example, the waste treatment plant (WTP) at Hanford is planning on using a highly-selective organic ion-exchange resin to remove Cesium and Strontium. Such organic ion-exchangers use molecular recognition to selectively bind to Cesium and Strontium. However, these organic ion-exchangers are synthesized using multi-step organic synthesis. The associated cost to synthesize organic ion-exchangers is prohibitive and seriously limits the scope of applications for organic ion-exchangers. Further issues include resin swelling, potential hydrogen generation and precluding final disposal by vitrification without further issues. An alternative to these issues of organic ion-exchangers is emerging. Inorganic ion-exchangers offer a superior chemical, thermal and radiation stability which is simply not achievable with organic compounds. They can be used to remove both Cesium as well as Strontium with a high level of selectivity under a broad pH range. Inorganic ion-exchangers can operate at acidic pH where protons inhibit ion exchange in alternative technologies such as CST. They can also be used at high pH which is typically found in conditions present in many nuclear waste types. For example, inorganic ion-exchangers have shown significant Strontium uptake from pH 1.9 to 14. In contrast to organic ion-exchangers, inorganic ion-exchangers are not synthesized via complex multi-step organic synthesis. Therefore, inorganic ion-exchangers are substantially more cost-effective when compared to organic ion-exchangers as well as CST. Selective removal of specified isotopes through ion exchange is a common and proven treatment method for liquid waste, yet various aspects of existing technologies leave room for improvement with respect to both cost and effectiveness. We demonstrate a novel class of inorganic ion-exchangers for the selective removal of cesium and strontium (with future work planned for uranium removal), the first of a growing family of patent-pending, potentially elutable, and paramagnetic ion-exchange materials [1]. These highly selective inorganic ion-exchangers display strong chemical, thermal and radiation stability, and can be readily synthesized from low-cost materials, making them a promising alternative to organic ion-exchange resins and crystalline silicotitanate (CST). By nature, these inorganic media lend themselves more readily to volume reduction (VR) by vitrification without the issues faced with organic resins. In fact, with a simple melting of the KMS-1 media at 650–670 deg. C (i.e., well below the volatilization temperature of Cs, Sr, Mn, Fe, Sb, etc.), a VR of 4:1 was achieved. With true pyrolysis at higher temperatures or by vitrification, this VR would be much higher. The introduction of this new family of highly specific ion-exchange agents has potential to both reduce the cost of waste processing, and enable improved waste-classification management in both nuclear power plants (for the separation of Class A from B/C wastes) and DOE tank farms [for the separation of low level waste (LLW) from high level waste (HLW)]. In conclusion, we demonstrate for the first time a novel inorganic ion-exchanger for the selective removal of Cesium and Strontium. These inorganic ion-exchangers are chemical, thermal and radiation stable. These inorganic ion-exchangers can be synthesized in a cost-effective way which makes them significantly more effective than organic ion-exchange resin and CST. Finally, new thermal options are afforded for their final volume reduction, storage and disposal.Copyright

Open-Pore Polyurethane as a Medium for Coal Conversion Process Aqueous Effluent Cleanup

Abstract A study was made of varying the reaction conditions of in-situ polymerized open-pore polyurethane (OPP). Optimum conditions were determined by electron microscopy and flow-rate studies. Using these conditions, large 1-in. × 12-in. columns were polymerized and compared, by use of a four-column bench-scale adsorption apparatus, with the same type columns filled with three common commercial adsorbents. Breakthrough curves (TOC, total phenol, etc.) of a synthetic and an actual coal conversion wastewater were then plotted for each of these columns.