Issue Number:PDR-202
Phase: Design
Decommissioning Process Processing/Disposal/Environment Remediation (including Wastes containing Alpha Nuclides originating from Fuels)
Investigation Subject Waste volume reduction and waste conditioning
Issue Waste conditioning method
Needs
① Improving the performance and reliability of waste package
Desired state and reasons for it
In order to improve the performance and reliability of waste package, it is desirable to select a waste conditioning technology in accordance with the properties of the waste and advance the technology and the evaluation method.
Current state against ideal
Prospects for the application of low-temperature treatment technologies to actual equipment are being confirmed through full-scale tests. At the same time, further studies are being conducted on solidification feasibility testing methods and on methods for evaluating the stability (leaching characteristics, long-term alteration phenomena, radiation effects, etc.) of solidified products produced by various treatment technologies.
Issues to be resolved
There is a wide range of waste properties, and it is necessary to select waste conditioning technology appropriate for each property.
It is necessary to have an index for judging whether the performance and reliability of a waste package is assured or not.
Some types of waste may need to be speedily transformed into a waste package for stabilization. Even in speedy waste conditioning, it is necessary to clarify in advance the requirements for waste package to avoid the need for further treatment.
It is necessary to evaluate the leaching performance of the produced solidification matters to groundwater after disposal.
With regard to the low-temperature and high-temperature treatment technologies that have been studied and developed so far, it is necessary to continue to address issues that have not yet been addressed (e.g., evaluation of waste streams whose applicability has not yet been studied, evaluation of the stability of the solidified products to be produced, etc.).
For the low-temperature treatment technology, it is necessary to study the solidification feasibility testing method and the alteration of the solidified product.
② Stabilizing the waste
Desired state and reasons for it
It is desirable to carry out safe and rational storing and management of wastes considering their properties and establish a method for rational selection of a preliminary treatment method.
From the viewpoint of reduction of the generated amount and cost of secondary waste, it is desirable to minimize the processes through final waste package.
It is desirable to establish treatment processes such as decomposition of substances that have adverse effects on processing and disposal if they are contained in the waste. (Adverse effects should not be dealt with on the disposal side, but on the processing side).
Current state against ideal
It has been conducted to confirm the prospects of actual application of high-temperature treatment technologies to ALPS slurries, etc. and to investigate in details to suppress Cs volatilization during treatment.
In order to contribute to expand the range of application of the low-temperature treatment technology and the technological options, the confirmation of applicability of intermediate treatment technologies such as pyrolysis treatment to detoxification of organic matter and inactivation of reactive and corrosive substances has been undertaken.
The following possibilities are being considered as a preliminary study of measures to flexibly and rationally respond to the challenges anticipated in the decommissioning work in the immediate future.
Technology for batch solidification of miscellaneous and large amounts of debris that are difficult to separate and may contain hazardous materials, etc., without separation.
Technology for integrated treatment of slurry dewatered materials and their containers that simplifies the previous process of treating slurry dewatered materials after stabilization treatment and eliminates the need for development related to removal from containers.
Issues to be resolved
Since for the wastes with high liquidity, there is relatively high risk in storing and management due to their liquidity, it is necessary to reduce the risk by a certain processing (such as vitrification) and conduct more stable and rational storing and management.
For each specification of solid waste to be processed, it is necessary to evaluate the safety of multiple rational and feasible disposal methods that are suitable for the characterization of the waste, without specifying the location or scale of the facility, by using scenarios, models, and data, etc. for safety assessment. Based on the evaluation results, it is necessary to investigate a selection technology for advanced processing methods.
In order to minimize the processes through final waste package, it is necessary to investigate measures for reducing the generated amount and the cost of secondary wastes.
It is necessary to investigate a verifying method for the presence/absence of substances that have adverse effects on processing and disposal and a processing method for these substances.
It is necessary to address the investigation of expanding the scope of application of low-temperature treatment technologies where R&D has been proceeded.
For waste streams that have not yet been investigated for application of low-temperature and high-temperature treatment technologies, evaluation of the application of the technologies should be conducted as necessary.
For low-temperature treatment technologies, a solidification feasibility test method should be investigated. For high-temperature treatment technologies, the feasibility of the entire treatment system, including not only the solidification process but also the supply and exhaust system, should be investigated at an appropriate time according to the start of treatment.
Since ALPS slurry is continuously generated in water treatment and storage capacity is an issue, it is necessary to give priority to the requirements for selection of treatment technology to be applied, taking into account the issues related to slurry dehydration treatment technology at the Specific Nuclear Facilities and Monitoring and Evaluation Study Group and at technical meetings for the review of implementation plans for specific nuclear facilities, and also giving due consideration to the issues associated with dehydration treatment.
Relevant Issues
References
- PDR-202 (PDF)
- Overall Diagram (HTML, PDF)
- Overall Diagram (Detailed Version) (PDF)
- Download all diagrams (diagram_en.zip, 9.4 MB)
- List of issues
Please note that this English text is a provisional translation of the Japanese original.