Presently, robots are deployed in the Fukushima Daiichi Nuclear Power Plant (NPP) for the implementation of survey, measurement and so forth in a high radiation environment within the buildings by remote control. Additionally, in the future it is anticipated that there will be an increasing needs for the robots to be used for the removal of rubble, installation of shielding and so forth. Furthermore, it is deemed necessary to prepare the robots for the decontamination work required to improve the environment within the buildings, and to apply the robots to the subsequent survey and repair works for reactor containment vessels.
To respond to such needs for the application of remote-controlled robots, development works have been in progress for a remote-controlled robot system utilizing wireless communication technology, a gamma camera for the measurement of gamma-ray intensity distribution, a small-scale double-arm heavy machinery-type robot for disaster-handling use “ASTACO-SoRa” and a remote-controlled decontamination device by using high-pressure water “Arounder”, thereby providing the capabilities to enable the robot to perform site surveys, rubble removal and an improvement in the environment.
This paper provides an introduction to the high-pressure water decontamination apparatus "Arounder" that is one of the above-mentioned robots developed thus far.

High-pressure water decontamination apparatus "Arounder*" was developed for the purpose of improvement of radiation contaminated environment in the disaster site of Fukushima Daiichi Nuclear Power Station in the subsidized project of the Agency for Natural Resources and Energy. The nuclear disaster site is a very harsh environment by radiation contamination; therefore it is necessary to control decontamination apparatuses, etc. remotely in order to reduce radiation exposure of workers.
To meet these needs, the remote control technology in nuclear facilities was utilized and a high-pressure water decontamination apparatus which is appropriate to decontamination work in the reactor building was developed.
The decontamination apparatus can improve radiation contaminated environment in the reactor building with preventing contaminated water diffusion after decontamination work by washing radiation material on the floor and wall with high pressure water and vacuuming up contaminated water at the same time. Also, Arounder makes it possible to travel through narrow passages due to a compact body and press a decontamination head which injects high-pressure water and vacuuming up contaminated water against the floor and wall with the arm. The specification of Arounder is shown in Table.1. The system configuration of Arounder is shown in Figure.1. High-pressure water is supplied from a high-pressure water pump and contaminated water is transported to a collecting tank; both are placed separately and connected to the main body with hoses. Arounder can be controlled remotely from a low radiation dose area by network, which makes operators’ radiation exposure lower. The photograph of the controller is shown in Figure.2.

* Arounder is a coined word that was named after a meaning "All-rounder" and “Around” because it deals with a wide range of contamination condition and runs around PCV (primary containment vessel) in the reactor building.

Phase 2: Industrial Confirmation Phase

1. (1) Components: within the Reactor building

1. (2) Location: Floor
   

1. (3) Materials: N/A

1. (4) Condition: Disaster site, Radiation environment
   

1. (1)Possible to select surface cleaning, paint peeling and chipping by adjusting water pressure. Water pressure can be adjusted from 25 up to 200 MPa. This makes it possible to select surface cleaning, paint peeling and chipping against decontamination target surfaces at the site. Therefore Arounder can deal with wide range of contamination condition at the site: surface contamination areas which can be decontaminated by removing surface sediment, contamination penetrated inside paint areas and contamination penetrated inside concrete areas.
   The maximum decontamination speed is 12m²/h in the case of floor surface cleaning. The water consumption is 2.6L/min at a water pressure of 30MPa.
   

1. (2)Possible to vacuum up contaminated water and chipped shard without spilling by optimizing the decontamination head.
   Arounder has the decontamination head which can inject high-pressure water and vacuuming up contaminated water at the same time. The decontamination head in which high-pressure water was injected can vacuum up decontamination water (supplied high-pressure water), contaminated water and chipped shard without spilling by optimizing brush surrounded high-pressure water nozzle. This makes it possible to prevent contaminated water diffusion and accomplish assured decontamination.
   The schematic drawing of the decontamination head is shown in Figure.3 and the photograph of example of chipping of concrete is shown in Figure.4.
   
   

1. (3)Possible to decontaminate up to 2 m in height by the arm.
   Arounder has the arm which can be pressed the decontamination head against the floor and wall. The arm has 4 degrees of freedom and can press the decontamination head against wall and decontaminate up to 2 m in height. The 4 degrees of freedom are made up of arm rotating, arm telescoping, arm hoisting and head hoisting.
   The arm can be folded inside the body; therefore it does not interfere with Arounder moving through the reactor building.
   

Table.1 The specification of Arounder

Figure.1 The system configuration of Arounder and its photograph

Figure.2 Photograph of the controller

Figure.3 Schematic drawing of the decontamination head

Figure.4 Photograph of example of chipping of concrete
(Water pressure: 190MPa / Feed speed: 2m/min / Decontamination width: 32mm)

Arounder successfully operated demonstrational operation of decontamination in the reactor building in Fukushima Daiichi NPP in April 2014.

1. [1]Hitachi-GE Nuclear Energy, Ltd., Remote Control Monitoring Robot System in Large-Scale Disaster Scenes, E-JAM Vol.5, No.2 (2013), NT-57, http://www.jsm.or.jp/ejam/Vol.5No.2/NT/NT57/NT57.html
2. [2]Hitachi-GE Nuclear Energy, Ltd., Double-arm Heavy Machinery-type Robot "ASTACO-SoRa", E-JAM Vol.6, No.1 (2014), NT-63, http://www.jsm.or.jp/ejam/Vol.6No.1/NT/NT63/63.html
3. [3]Hitachi-GE Nuclear Energy, Ltd. Homepage,
   http://www.hitachi-hgne.co.jp/news/2013/20130308.html
4. [4]日刊工業ビデオニュース「日立ＧＥニュークリア、遠隔除染装置を開発」, http://www.youtube.com/watch?v=8fe4hYcF8-E

Japan Society of Maintenology (ejam@jsm.or.jp)