Development of Decommissioning and Radwaste Treatment Technology        

Support for
improvement ofrelated regulations

Geologicaldisposal

Planning ofdisposal facilities

Shallow land disposal

Support for
improvement ofregulations related todisposal of radwaste

Subsurface disposal

Waste
package

Treatment andstorage of radwaste

Operation and maintenanceof existing waste treatment
facilities (Advanced volume Construction of waste
reduction facilities etc.)
treatment facilities at
each site

Clearance

TechnologyDevelopmentof Relevant

Waste from dismantlingDecommissioningof nuclear facilities

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





Decommissioning of aging nuclear facilities or nuclear
facilities completing their missions
Consolidation/Reuse of facilities and equipments  



 

Decommissioning and radwaste treatment/disposal are twoof our major missions. In these missions, we will bedisposing of radwaste arising not only from our research
activities but also those of universities, institutes, industrial
facilities, etc.
We are setting up systems for the decommissioning ofnuclear facilities and for radwaste management, throughrelated technology development, planning and constructionof radwaste treatment/disposal facilities, and support for
improvement of related regulations (Fig.9-1).
 
We are developing a decommissioning engineering system
and a waste/scrap material clearance verification/evaluationsystem.
To develop this decommissioning engineering system, amethod for evaluating decommissioning cost efficiently
which is applicable to various types of nuclear facilities has
been constructed (Topic 9-1).
  In order to dispose of radwaste in a cost effective manner,research in the following waste treatment techniques is being
conducted: a nitrate degradation method for low level
effluent, a cement solidification technique for incinerationashes, and a decontamination technique using supercriticalcarbon dioxide fluid to remove plutonium from radwaste.
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



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 

Furthermore, we have developed a waste management
system which is used for systematic management of theradwaste data acquired through various operations fromgeneration to disposal of the wastes. This management
system supplies the data needed for safety assessment ofdisposal of radwaste etc. (Topic 9-2).
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
 Studies on rapid measurement of various radionuclides areunderway to establish practical methods to evaluate theradioactive inventory in waste packages.
By literature review and actual measurements of naturaluranium concentration, the contribution of uranium to natural
background radiation has been estimated (Topic 9-3). This
result will be applied to conceptual design of a clearance anddisposal system for uranium bearing waste, taking into
consideration the existence of natural uranium.
As for study on a subsurface disposal system for uraniumbearing waste, exposure dose in the case of “less-likelyscenarios” was preliminary calculated to be less than“standard dose value” recommended by Nuclear Safety
Commission.
In addition, radioactivity concentrations in radwaste
generated by reactor facilities were characterized. This date
will be used for safety assessment which will be applied
during the implementation of disposal.