Agricultural Land Management Options Following Large-Scale Environmental Contamination: Evaluation for Fukushima Affected Agricultural Land

The accident at the Fukushima Daiichi Nuclear Power Plant has raised questions about the accumulation of radionuclides in soils, the transfer in the foodchain and the possibility of continued restricted future land use. This paper summarizes what is generally understood about the application of agricultural countermeasures as a land management option to reduce the radionuclides transfer in the food chain and to facilitate the return of potentially affected soils to agricultural practices in areas impacted by a nuclear accident.

General Approach to the Long-Term Management at a Former Radium Production Site in Olen, Belgium

The paper describes the methodology that ONDRAF/NIRAS, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials, in consultation with the metallurgical company who aims the Olen-site, is developing and wants to apply to arrive at a safe and sustainable long-term solution in Olen. The complex problematic in Olen and how this does fit in the legal missions of ONDRAF/NIRAS is also presented.

Feasibility Study on Phytoremediation Techniques for Soil Contaminated by the Fukushima Dai-Ichi Nuclear Power Plant Accident

Tottori University and the Japan Atomic Energy Agency carried out jointly the feasibility study on phytoremediation techniques, which apply to soil contaminated by the TEPCO’s Fukushima Dai-ichi NPP accident. This paper illustrates the results from experimental investigations. Experimental investigations include both water-culture tests and field tests. Several plants, mainly halophytes that can specifically absorb more Na than K, and others like sunflower demonstrated for other domestic large-scale tests, were water-cultured and examined for screening. Easily cultivated and harvested plants without harmful effects on subsequent cultivation were also considered. New Zealand spinach was selected as a candidate for demonstrations in fields. The field tests were carried out at two sites of different agricultural types in Minami-soma, Fukushima prefecture. Concentration of 137Cs in soil is about 4.5 Bq/g-dry as the average of 10 cm depth. The aims of the field tests are to confirm absorption ability and environmental adaptation of the test plants and to document the cost and performance of projects. In conclusion, the absorption of 137Cs activity per unit area (Bq/m2) by New Zealand spinach could be approximately 0.5%. To achieve an effective result in removal of 137Cs from soil in around a decade, it is required to find the plant which has ten or more times higher absorption capacity than New Zealand spinach. From the consistency of both results in water-culture and field tests, the water-culture test can be valid for screening. In addition, applicable sites will be limited to fields which are too steep or too narrow to use mechanical diggers, and which are free from any restrictions to enter.

From Passive Storage to Daily Waste Retrieval; Changing the Working Culture at Sellafield’s Pile Fuel Storage Pond

The Pile Fuel Storage Pond (PFSP) was built in 1948/50 to treat materials from the Windscale Piles. Multiple operational regimes over the intervening 60 years have resulted in a complex inventory of spent nuclear fuels, solid and liquid intermediate level wastes. A coordinated programme of work, designed to retrieve and safely dispose of the pond contents, has been implemented to enable the decommissioning of the facility. The long period of passive storage operations which preceded the implementation of the programme meant that the operator was faced with a dual challenge of providing new technical capability and changing a working culture that was inappropriate for the dynamic environment required to successfully deliver the programme. It was recognised that the nature of the programme meant that implementing a standard manufacturing approach to operations would not be appropriate. In order to create a dynamic retrievals focussed working culture, the operator has vigorously embraced change programmes aimed at improving a number of working practices including encouraging innovation, managing integrated but flexible production schedules, and encouraging workface problem solving. The combined impact of beginning to resolve the technical challenges and focussing on the delivery culture has resulted in the facility making a step change towards becoming fully retrievals operations focussed.

Decommissioning of the Hematite Former Fuel Cycle Facility Using a Decision Flow Logic Based Work Control Process

The remediation and decommissioning of the Hematite Former Fuel Cycle Facility (FFCF), the Hematite Facility, is currently being carried out by Westinghouse Electric Company LLC under the Hematite Decommissioning Project (HDP). The Hematite Facility is located near the town of Hematite, Missouri, USA. The Hematite Facility consists of 228 acres of land with primary operations historically being conducted within the central portion of the property that is roughly 10 acres including Burial Pits and the Site Pond area. Decommissioning and remediation activities are being performed with the eventual objective of the release of the property. Primary contaminants include the legacy disposal and contamination of natural and enriched uranium from the nuclear fuel cycle, as well as chemicals used during the facility operations. Two major regulatory bodies, the U.S. Nuclear Regulatory Commission (NRC) and the Missouri Department of Natural Resources (MDNR), provide critical roles in the approval and oversight of the current regulatory path to remediation, decommissioning and eventual release. Further, remediation and decommissioning activities are performed under the implementing policies, plans, and procedures under the Hematite Decommissioning Plan (DP) and the Record of Decision (ROD). Remediation and decommissioning tasks at the Hematite Former Fuel Cycle Facility, referred to as the Hematite Facility, are performed against a disciplined decision logic flow that applies accumulated technical and monitoring data to determine each step of the excavation, exhumation, and removal of wastes from the Burial Pits and the remaining Areas of Concern (AOC). Decision flow logic is based upon the nuclear criticality safety controls and threshold conditions, relative level of radioactive and chemical contamination, security protocol, and final waste stream disposition. The end result is to remediate the residual radioactive and chemical contamination to approved dose-based and risk-based cleanup criteria as negotiated with U.S. Federal and State Regulators. The purpose of the paper is to provide a summary of the successful implementation of the decision flow logic to the remediation and decommissioning tasks performed to date.

The Regulatory Framework for Safe Decommissioning of Nuclear Power Plants in Korea

We are having 23 units of nuclear power plants in operation and 5 units of nuclear power plants under construction in Korea as of September 2012. However, we don’t have any experience on shutdown permanently and decommissioning of nuclear power plants. There are only two research reactors being decommissioned since 1997. It is realized that improvement of the regulatory framework for decommissioning of nuclear facilities has been emphasized constantly from the point of view of IAEA’s safety standards. It is also known that IAEA will prepare the safety requirement on decommissioning of facilities; its title is the Safe Decommissioning of Facilities, General Safety Requirement Part 6. According to the result of IAEA’s Integrated Regulatory Review Service (IRRS) mission to Korea in 2011, it was recommended that the regulatory framework should require decommissioning plans for nuclear installations to be constructed and operated and these plans should be updated periodically. In addition, after the Fukushima nuclear disaster in Japan in March of 2011, preparedness for early decommissioning caused by an unexpected severe accident became important issues and concerns. In this respect, it is acknowledged that the regulatory framework for decommissioning of nuclear facilities in Korea need to be improved. First of all, we focus on identifying the current status and relevant issues of regulatory framework for decommissioning of nuclear power plants compared to the IAEA’s safety standards in order to achieve our goal. And then the plan is established for improvement of regulatory framework for decommissioning of nuclear power plants in Korea. It is expected that if the things will go forward as planned, the revised regulatory framework for decommissioning could enhance the safety regime on the decommissioning of nuclear power plants in Korea in light of international standards.

Integrated Systems-Based Approach to Monitoring Environmental Remediation

The U.S. Department of Energy is responsible for risk reduction and cleanup of its nuclear weapons complex. Remediation strategies for some of the contamination may include techniques that mitigate risk, but leave contaminants in place. Monitoring to verify remedy performance and long-term mitigation of risk is key to implementing these strategies and can be a large portion of the total cost of remedy implementation. Especially in these situations, there is a need for innovative monitoring approaches that move away from the cost- and labor-intensive point-source monitoring. In this paper, alternative approaches for monitoring are presented for vadose zone, groundwater, groundwater/surface water interface, and surface water. To illustrate integrated, systems-based monitoring, this paper focuses on vadose zone contaminant remediation to mitigate impact to groundwater. In this context, vadose zone contamination is a source, or potential source, to groundwater plumes. The monitoring design uses a systems-based approach focused on developing a conceptual site model that highlights key features that control contaminant flux to groundwater. These features are derived considering the unsaturated flow and contaminant transport processes in the vadose zone and the nature of the waste discharge. Diagnostic properties and/or parameters related to both short- and long-term contaminant flux to groundwater can be identified and targeted for monitoring. The resolution of monitoring data needed to correspond to a functionally useful indicator of flux to groundwater can be estimated using quantitative analyses and the associated unsaturated flow properties relevant to the targeted site and vadose zone features. This monitoring design approach follows the process of developing a quantitative conceptual model suitable for supporting projections of future flux to groundwater. Support for such projections is important because it is likely that, in many cases, remediation decisions for the vadose zone will need to be made based all or in part on projected impacts to groundwater, and monitoring will then be applied to verify that remedy goals are being met.

Effects of Precipitation on Surface-Scan Gamma Ray Survey Results: Case Study

It has been known for many years that certain weather events (e.g., precipitation, low barometric pressure, etc.) can affect the results of outdoor gamma-ray surveys, particularly those where gamma spectroscopy is being used for the detection of uranium and its progeny. These effects are a result of a natural phenomenon that produces anomalous results that are contrary to the true concentrations present at the survey site. Gamma-ray survey results sometimes overestimate uranium concentrations during and immediately following rain or snowfall events. The effects that a precipitation event has upon a drive-over gamma-ray survey are discussed in this paper. Surveys were conducted using a sensitive array of sodium iodide (NaI) detectors mounted to an all-terrain vehicle in late fall/early winter where snow was encountered. Isotope-specific measurements taken before and during precipitation events are compared and visually presented in iso-contour maps.

Development of Evaluation Models of Manpower Needs for Dismantling the Dry Conversion Process-Related Equipment in Uranium Refining and Conversion Plant (URCP)

Evaluation models for determining the manpower needs for dismantling various types of equipment in uranium refining and conversion plant (URCP) have been developed. The models are widely applicable to other uranium handling facilities. Additionally, a simplified model was developed for easily and accurately calculating the manpower needs for dismantling dry conversion process–related equipment (DP equipment). It is important to evaluate beforehand project management data such as manpower needs to prepare an optimized decommissioning plan and implement effective dismantling activity. The Japan Atomic Energy Agency (JAEA) has developed the project management data evaluation system for dismantling activities (PRODIA code), which can generate project management data using evaluation models. For preparing an optimized decommissioning plan, these evaluation models should be established based on the type of nuclear facility and actual dismantling data. In URCP, the dry conversion process of reprocessed uranium and others was operated until 1999, and the equipment related to the main process was dismantled from 2008 to 2011. Actual data such as manpower for dismantling were collected during the dismantling activities, and evaluation models were developed using the collected actual data on the basis of equipment classification considering the characteristics of uranium handling facility.

Characterising Nuclear Simulant Suspensions In Situ With an Acoustic Backscatter System

In situ characterisation of radiotoxic sludges and slurries is critical to numerous operations including those involving their transport and retrieval. An inexpensive, flexible acoustic backscatter system has been employed for the first time here to a 4/10th scale active storage tank comprising of a nuclear simulant suspension, to verify its application. Intricate suspension characteristics and tank operation features emerged.