IRID published English language versions of their fuel debris removal and other new technology research reports. Various contractors were hired to conduct research towards the best way to remove the melted fuel inside the reactor buildings at Fukushima Daiichi.
The reports all showed dry methods for removing fuel both from the top and from the side of the containment vessels.
The ATOX/Areva plan involved processing removed debris in the outer reactor building in some way but didn’t clarify how that might work.
Japan Clean Environment’s plan involved the use of “steel balls” as a type of flexible shielding while working cutting tools on highly radioactive debris.
Multiple reports cited the need for much more data about the condition of the building and structures to be able to properly anticipate risks and to implement an effective design. The need for some type of containment entry system to allow equipment and debris entry and egress is mentioned in all reports. An air handling system to pull air and potential hydrogen out of the building with sufficient filtration is also mentioned in most reports.
Illustrations below from ATOX and IHI show possible fuel removal concepts.
QI company tested a camera under high radiation conditions. Some components fared well, others had failures. They found that cabling was deteriorated by the radiation along with the pan/tilt equipment in the camera head. The transmitted image also suffered from white noise from the radiation source.
Createc offered an option using an existing robotic snake arm and a 3D camera technology that was already proven to be radiation resistant. This technology option could provide imagery for hard to reach locations in containment.
Hamamatsu was able to develop a small camera that maintained a working but degraded image after high radiation exposure. They hoped to improve upon the technology with more research.
Fujikura is working on a fiber optic camera set up that seems to have good potential. They still need to conduct high radiation tests but the design has promise since the bulk of the electronics can reside remotely in relation to the radiation source being inspected.
IHI is working on two concepts. One is a laser cutter, the other a nitrogen gas based cutter. Both were able to cut the sample materials. They needed to conduct more research on hydrogen controls when cutting substances with high zirconium levels and also high radiation exposure tests for the equipment.
Onet’s laser cutter technology was run through high radiation tests. They found that this exposure did degrade the fiber optics in the laser cutter. They proposed that additional research into materials could improve radiation resistance.
The cutting technology by Taisei uses a diamond tipped bore cutter. This is roughly similar to technology used at Three Mile Island but would need testing on newer and improved versions. This proposal also mentions an implementation of wireless data monitoring in the reactor area. They did not provide any additional details on what wireless equipment could potentially handle the conditions in the reactor building.
These reports give some idea of the direction of the research towards fuel removal. It is assumed that IRID would give some additional direction for more research work and potential funding.
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