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Robots inradioactiveenvironments


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Robots inradioactiveenvironments

  1. 1. Robots In Radioactive Environments Seminar2004 ABSTRACT Robots were developed to reduce the human work and increase the precisionof work. Now, this can be applied to radioactive environment encountered innuclear power plants. As human safety is of primary importance, so robots aretaking over from human beings in radioactive environment. Now different types of telerobots are used in the nuclear power plants whichcan access anywhere in the nuclear power plants, thus reducing human exposure.Apart from the high initial cost, it is cheaper than using professional workers inlong run. The future of robots used in radioactive environment is expected to reach aphase where the nuclear power plants can be made devoid of human beings. Thiswould be possible only with the arrival of completely automatic fractal robots. 1 MES College of Engineering, Kuttippuram
  4. 4. Robots In Radioactive Environments Seminar2004 CHAPTER 1 INTRODUCTION Robots are developed to be used in areas inaccessible to human beings.Radio active environment is one in which high energy radiations like α, β and γradiations are emitted by radioactive materials. There is a limitation in case of thetime and dose for which professional worker can be exposed to nuclear radiationsaccording to international regulations so it very useful to use robots in such anenvironment. Robots with properly automated can also be used to control nuclear powerplants and hence can be used to avert nuclear power plant disasters like one thatoccurred at Chernobyl. Robots can also be used for the disposal of radioactivewaste. Future is still bright for robots in radio active environment as they are to beused to isolate nuclear power plants from surroundings in case of a nuclear powerplant disaster. 4 MES College of Engineering, Kuttippuram
  5. 5. Robots In Radioactive Environments Seminar2004 CHAPTER 2 BRIEF HISTORY The word robot was introduced in 1921 by the Czech play Wright KarelCapek, in his play Rossum’s universal robots and is derived from the Czech word“Robota”, meaning “forced labour”. The story concerns a brilliant scientist named‘ROSSUM’ and his son, who developed a chemical substance similar toprotoplasm to manufacture robots. Their plan was that the robots would serve themankind obediently and do all physical labour. Finally, after improvements andeliminating unnecessary parts, they develop a “perfect robot”, which eventuallygoes out of control and attacks humans. Although Capek introduced the word robot to the world, the term roboticswas coined by Isaac Asimov in his science fiction story “run around”, where heportrayed robots not in negative manner but built with safety measures in mind toassist human beings. Asimov established in his story three fundamental laws ofrobots as follows: 1. A robot may not injure a human being or, through inaction, allow a human being to come to harm. 2. A robot must obey the orders given to it by human beings, except where such orders would conflict with the first law. 3. A robot must protect its own existence as long as such protection does not conflict with the first and second laws. . Robots were introduced into the industry in the early 1960’s. Robots originally were in hazardous operations, such as handling toxics and radioactive materials and loading & unloading hot work pieces from furnaces and handling them in foundries. 5 MES College of Engineering, Kuttippuram
  6. 6. Robots In Radioactive Environments Seminar2004 CHAPTER 3 BASIC COMPONENTS OF A ROBOT The basic components of any complex industrial robot are as follows:3.1 Manipulator The manipulator is a mechanical unit that provides motion similar to thatof a human arm. Its primary function is to provide the specific motions that willunable the tooling at the end of the arm to do the required work. The individualjoint motions are referred to as degrees of freedom. Typically, industrial robotsare equipped with 4 to 6 degrees of freedom. The wrist can reach a point in spacewith specific orientation by any of the three motions: a pitch or up- and- downmotion; a yaw, or side- to- side motion; and a roll, or rotating motion. Themanipulator, therefore, is apart of the robot that physically performs the work.The points that a manipulator bends, slides or rotates are called joints or positionaxes. Manipulation is carried out using mechanical devices, such as linkages,gears, actuators and feedback drives. Fig 3-1: Manipulator 6 MES College of Engineering, Kuttippuram
  7. 7. Robots In Radioactive Environments Seminar20043.2 End Effecter A robot can become a production machine only if a tool or device has beenattached to its mechanical arm by means of the tool mounting plate. Robot toolingis referred to as end of arm tooling (EOAT) is commonly used both by industryand in publications. If the end effecter is a device that is mechanically opened andclosed, then it is called a gripper. If the end effecter is a tool or a specialattachment, then it is called process tooling. Depending on the type of operations, conventional end effectors areequipped with various devices and tool attachments as follows:  Grippers, hooks, scoops, electromagnets, vacuum cups and adhesive fingers for material handling.  Spray gun for painting.  Attachments for spot and arc welding and arc cutting.  Power tools, such as drills, nut drivers and burrs.  Special devices and fixtures for machining and assembly.  Measuring instruments such as dial indicators, depth gauges and the like.3.3 Power Supply The function of the power supply is to provide and regulate the energy thatis required for a robot to be operated. The three basic types of power supplies areelectric, hydraulic and pneumatic. Electricity is the most common source ofpower and is used extensively with industrial robots. The second most common ispneumatic and the least common is hydraulic.3.4 Controller The controller is a communication and information processing device thatinitiates, terminates and coordinates the motion and sequences of a robot. It 7 MES College of Engineering, Kuttippuram
  8. 8. Robots In Radioactive Environments Seminar2004accepts the necessary inputs to the robots and provides the output drive signals toa controlling motor or actuator to correspond with the robot movements andoutside world. Controllers vary greatly in complexity and design. They have a great dealto do with functional capabilities of a robot and therefore, the complexity of thetasks that robots must be able to fulfil. The heart of the controller is the computer and its solid state memory. Inmany robot controllers, the computer includes a network of microprocessors. The input and output section of a control system must provide acommunication interface between the robot controller computer and the followingparts:  Feed back sensors  Production sensors  Production machine tools  Teaching devices  Program storage devices  Other computer device hardware 8 MES College of Engineering, Kuttippuram
  9. 9. Robots In Radioactive Environments Seminar2004 Fig 3-2: Block Diagram of a Controller CHAPTER 4 NEED FOR ROBOTS IN RADIOACTIVE ENVIRONMENT Radioactive environment is mainly encountered in nuclear power plants.Some regular repair and maintenance activities at nuclear power plants involverisks of contamination and irradiation. While contamination is an accidental andavoidable phenomenon, irradiation is continuous and effects the operators workareas. Various countries have laws establishing annual maximum doses to whichprofessional workers can be exposed and the maximum time that they may stayinside areas subject to radiation. Most tasks at nuclear facilities are carried out by in house maintenancespecialists. They are few in number and in many cases, require several yeas ofexperience and extensive training programs. The number of hours that they canwork continuously is limited by national international regulations regarding themaximum dose that may be received by exposed professional workers. Legalregulations establish that when a worker reaches a specific dose limit, the workercannot work in areas subject to radiation for a given period of time. This increasethe cost of maintenance services because personal only operate for short periodsof time. Given the discontinuous use of human resources and discontinuousnature of work, nuclear service companies are obliged to allow for someuncertainties in scheduling of services and in rationalization of their humanresources. For all the above reasons, it is generally advisable and in some casesmandatory, to use telerobotics for the execution of repair and maintenance tasks 9 MES College of Engineering, Kuttippuram
  10. 10. Robots In Radioactive Environments Seminar2004in nuclear power plants. This is particularly true of tasks entailing high exposureto radiation. CHAPTER 5TYPICAL NUCLEAR TELEROBOTIC APPLICATIONS IN PRESSURISED LIGHT WATER (PWR) REACTORSThese are some of the typical surveillance and maintenance operations in pwrunits where telerobotic systems can be applied.1. Steam generator  Primary tube inspection and maintenance.  Channel head cleaning and decontamination.  Nozzle dam insertion.  Sludge lancing  Secondary side foreign object removal.  Foreign object removal in the primary circuit.2. Reactor cavity  Floor and wall area decontamination.  Fuel transfer channel cleaning.  Fuel transfer channel and underwater inspection.3. Reactor vessel  Underwater inspection and repair.  Foreign fallen object removal.  Lower internal inspection.4. Reactor head vessel  Surface decontamination. 10 MES College of Engineering, Kuttippuram
  11. 11. Robots In Radioactive Environments Seminar2004  Head inspection.5. Others  Internal pipe inspection and object removal.  Underwater cleaning of various plant tanks and vessels.  Surface decontamination of general floor areas.  Underwater inspection of equipment and spent fuel pools.  Extraction and welding of the pressurized heaters. CHAPTER 6 ROBOTS USED IN NUCLEAR POWER PLANTS6.1. Remotely operated service arm (ROSA) Radioactive environment in which robots work is actually seen in nuclearpower plants. The tubes in steam generators are subject to multiple stresses, suchas mechanical and thermal loading, vibrations and various types of corrosion.Diagnostic tests are therefore necessary to identify points of degradation along theSG tubes and define repair procedures for damaged tubes. The SG maintenancejobs, which are carried out during plant refuelling outages, involve complex tasks(water cleaning, nozzle dam insertion, eddy-current inspection, mechanicalplugging and unplugging etc) inside an environment made hazardous by highradiation and contamination. The frequency of inspection and the number ofinspected tubes increases with the aging of the plant. So a telerobotic systemknown as remotely operated service arm is used to the use of jumpers that workinside the SG channel head, thus lessens the risk of contamination of humanworkers. The system has proven its robustness and flexibility for a wide range ofmaintenance operations inside the SG channel head of PWR SGS. The systemprovides a remote user interface for controlling the joint six axis arm. The arm isequipped with a remote quick connector (RQC) to facilitate the assembly anddisassembly of such tools. 11 MES College of Engineering, Kuttippuram
  12. 12. Robots In Radioactive Environments Seminar2004 Fig 6-1: ROSA6.2. INSPECTION AND RETRIEVING VEHICLE (IRV) During maintenance operations inside the SG channel heads, objects mayaccidentally fall inside the primary circuit nozzle. When this happens, it isnecessary to develop special tools to remove fallen objects. These tools are oftenhandled by jumpers from the channel head nozzle, so the accumulated doses arevery high. This is not particularly frequent incident, but because it has happenedin past and entails high exposure to radiations for workers, nuclear plants demandthat contingency procedures may be put in place. The inspection and retrievingvehicle system is a teleoperated vehicle provided with sensors, lights, camerasand interchangeable end-effectors that allow these operations to be carried outfrom safe place.6.3. CLEANING AND RETRIEVING VEHICLE (CRV) An amount of radioactive waste gathers as a result of the refuellingoperation, transfer of fuel elements and general cleaning of the pool. This pit,located at the lowest level close to the transfer channel, is one of the hot pointswhere workers are generally exposed to moderate but occasionally very highlevels of radiation. The design of cleaning and retrieving vehicle telerobotics system is based onthe IRV. The CRV is a teleoperated vehicle that works underwater. It is equipped 12 MES College of Engineering, Kuttippuram
  13. 13. Robots In Radioactive Environments Seminar2004with a rotating brush to pick up the dirt and a pump to remove it to an externalshielded filter.6.4. TRON During refuelling operation, parts of tools or other objects can fall into the vesselbecause of human error or other circumstances. The teleoperated and robotizedsystem for maintenance operation in nuclear power plant vessels is a four jointedrobotized pole used to retrieve fallen objects from the PWR reactor vessel. Thepole is inserted through the holes in the lower core plate. In this way, it caninspect the lower internal zone and recover objects without the core having to bedisassembled. The whole system comprises a jointed pole, end-effectors and a computervision navigation system that helps the operator to move through a highlycomplex environment. The end-effector and the inspection cameras are attachedto the end link. More complex mechanism cannot be used because of the smallsize of the flow holes.6.5. ELECTRIC MASTER SLAVE MANIPULATOR The EMSM range of Electrical Master Slave Manipulators has beendeveloped for use in high dose environments where intricate and/or heavy dutywork is carried out. Master arms operated by the user transfers exact motions kinematically tothe slave manipulator. Throughout the process, the user is given a realistic feelingof forces and moment as, import  Realistic force feedback  Effortlessly handles loads of up to 100 kg  All purpose manipulator designed to be used with standard tools: grinders, drills, screwdrivers.6.6. SNAKE-LIKE ROBOTS 13 MES College of Engineering, Kuttippuram
  14. 14. Robots In Radioactive Environments Seminar2004 When disasters like nuclear power plant explosions occur, power plantpersonnel are often faced with a problem: how to find the reasons for nuclearpower plant explosions, so that future disasters can be avoided. The answer maybe robotic animals that can venture to hard to reach places that are inaccessible topeople.Mother Nature as MuseRobotic researchers are looking more and more to mimic nature for the shapesand functions of their mechanical creations. At North Carolina State University,when students were challenged to come up with a robot that could crawl throughpipes, they looked to the animal world for a clue. The idea came to Eddie Grant, director of the Center for Robotic andIntelligent Machines and a visiting professor at NC State, when he spoke with amajor in the Marine Corps who had been called out to the Oklahoma Citybombing. Grant realized that a robot that could navigate pipes would be ideal inthis situation because pipes generally stay intact when the rest of a structure hascollapsed. The senior design students created robots called MOCASIN I andMOCASIN II (Modular Observation Crawler And Sensing Instrument) that cancrawl through six-inch pipingHow Does It Work? MOCASIN II is a segmented robot that looks somewhat like an inchworm.It uses pneumatics (air pressure) to force padded "feet" against the pipe walls,contracting and expanding its "body" in the process. The use of pneumatics formovement is an important factor because sometimes there are explosive gasespresent in nuclear power plants that have exploded. Since electricity might ignite 14 MES College of Engineering, Kuttippuram
  15. 15. Robots In Radioactive Environments Seminar2004the gases, the robot uses compressed air, which also allows it to run off of airtanks when no electricity is available. The robot is designed so that it breaks downinto components that can be easily transported to remote sites. A tiny video camera and lights allow rescuers to see where MOCASIN IIis located. The robot can also be equipped with sensors that could pick upvibrations from someone tapping on the pipes, or even "hear" voices and perhapsbreathing.What Else Could It Do?Robots like MOCASIN II could eventually have other uses, as well. They couldbe used for repairs in dangerous areas, such as nuclear power plant pipes, or todetect cracks in sewer or water lines. They could used to rescue people fromrubbles after massive earthquakes. They could be even used in other planets. Researchers at NASA’s Ames Research Center are currently developingrobots that resemble snakes to be used on the unknown terrain of other worlds.The snake-like design has several advantages. It allows the robots to be flexibleand adaptable, plus they can fit into tight spaces and move over large objects. TheSerpentine Robotics Project is working on adding pressure and light sensors to therobots as well. Like the MOCASIN, the robots use standard parts and electronics,but in this case they really resemble snakes. Robotic snakes that even imitate theslithering movement of the real thing, has been developed. While it may be a while before snake robots are used in space, rescuers onthis planet are likely to find such robots an invaluable tool. 15 MES College of Engineering, Kuttippuram
  16. 16. Robots In Radioactive Environments Seminar20046.7. AUTONOMOUS ROBOT FOR KNOWN ENVIRONMENT(ARK) The ARK (Autonomous Robot for a Known Environment) Project was aprecompetitive research project involving Ontario Hydro, the University ofToronto, York University, Atomic Energy of Canada Ltd., and the NationalResearch Council of Canada. The project started in September 1991 andcompleted in August 1995. The technical objective of the project was to develop asensor-based mobile robot that could autonomously navigate in a knownindustrial environment. There are many types of industrial operations and environments for whichmobile robots can be used to reduce human exposure hazards, or increaseproductivity. Examples include inspection for spills, leaks, or other unusualevents in large industrial facilities, materials handling in computer integratedmanufacturing environments, and the carrying out of inspections, the cleaning upof spills, or the carrying out of repairs in the radioactive areas of nuclear plants -leading to increased safety by reducing the potential radioactive dose to workers. The industrial environment is significantly different from officeenvironments in which most other mobile robots operate. The ARK projectproduced a self-contained mobile robot with sensor-based navigation capabilitiesspecifically designed for operation in a real industrial setting. The ARK robot wasevaluated in the large engineering laboratory at AECL CANDU in Mississauga,Ontario. This open area covers approximately 50,000 sq. feet of space andaccommodates one hundred and fifty employees. Within the Laboratory, there aretest rigs of various sizes, mockups of reactor components, a machine shop, afabrication facility, a metrology lab and assembly area. There are no majorbarriers between these facilities and therefore at any one time there may be up tofifty people working on the lab floor, three fork lift trucks and floor cleaning 16 MES College of Engineering, Kuttippuram
  17. 17. Robots In Radioactive Environments Seminar2004machines in operation. Such an environment presents many difficulties thatinclude: the lack of vertical flat walls; large open spaces (the main isle is 400long) as well as small cramped spaces; high ceilings (50); large windows near theceiling resulting in time dependent and weather dependent lighting conditions, alarge variation in light intensity, also highlights and glare; many temporary andsemi-permanent structures; many (some very large) metallic structures; peopleand forklifts moving about; oil and water spills on the floor; floor drains (whichcould be uncovered); hoses and piping on the floor; chains hanging down fromabove, protruding structures, and other transient obstacles to the safe motion ofthe robot. Large distances, often encountered in the industrial environment, requiresensors that can operate at such ranges. The number of visual features (lines,corners and regions) is very high and techniques for focusing attention onspecific, task dependent, features are required. Most mobile robotic projectsassume the existence of a flat ground plane over which the robot is to navigate. Inthe industrial environment this ground plane is generally flat, but regions of thefloor are marked with drainage ditches, pipes and other unexpected low lyingobstacles to movement. The ARK robot required sensors that can reliably detectsuch obstacles. The ARK robots onboard sensor system consisted of sonar’s and one ormore ARK robotic heads and a floor anomaly detector (FAD). The head consistsof a colour camera and a spot laser range finder mounted on a pan-tilt unit. Thepan, tilt, camera zoom, camera focus and laser distance reading of the ARKrobotic head are computer controlled. The ARK robot must navigate through its environment autonomously andcannot rely on modifications to its environment such as the addition of radiobeacons, magnetic strips beneath the floors, or the use of visual symbols added to 17 MES College of Engineering, Kuttippuram
  18. 18. Robots In Radioactive Environments Seminar2004the existing environment. In order to navigate within this environment the ARKrobot used naturally occurring objects as landmarks. The robot relied on vision asits main sensor for global navigation, using a map of permanent structures in theenvironment (walls, pillars) to plan its path. While following the planned path, therobot locates known landmarks in its environment. Positions and salientdescriptions of the landmarks are known in advance and are stored in the map.The robot uses the measured position of the detected landmarks to update itsposition with respect to the map. CHAPTER 7 FUTURE USE OF ROBOTS IN RADIOACTIVE ENVIRONMENT Robots have to be used in handling nuclear materials because of its toxiceffects on life. Nuclear accidents are the most difficult to deal with at present andexperience has shown that humans can only run away from nuclear accidents inthe face of danger just like a comical Neolithic ancestors running away in the faceof fire. Fractal robots presented here explains in detail how best to managenuclear accidents. At its simplest a fractal robot is simply a collection of computer controlledbricks that reshape on command into different structures in a matter of seconds.It’s like kids playing with Lego-instead we use a computer and motorised bricksand do this with total automation. 18 MES College of Engineering, Kuttippuram
  19. 19. Robots In Radioactive Environments Seminar2004 Fractal robots can limit an evolving nuclear accidents as it occurs bysealing the roof top of the building that have been blown and leaking radiationdusts. Penetrating intense radiation from nuclear accident can prevent any kind ofrepair work from being undertaken inside the building. This penetrating nature ofradiation requires that all machinery be operated remotely. Standard remotemachinery such as robotic rovers cannot operate in high radiation environments,confined spaces or an undefined terrain created by explosions that simply rulesout existing approaches. Fractal robots on the other hand can overcome all thesedifficulties systematically because it is a true multi-terrain vehicle to get fromanywhere to anywhere across undefined terrains.7.1 Characterising and Limiting Nuclear Accident A nuclear reactor that has been severely damaged is never accessibledirectly for servicing or repairs. The concrete reactor is normally surrounded byinstallation specific buildings that can make access difficult after an accident.Access constrains make the task of clearing up catastrophic reactor failure nearimpossible using conventional systems. It is the chemical or pressure explosion or both that rips the dome of thereactor and destroys other parts of the installation. These kinds of explosions aretypical of explosions that have ripped through the installations in the past. Thereis debris everywhere and terrain is generally undefined. A legged robot couldbecome trapped in the debris and so would small robots which are of little useanyway once they reach their objectives. Large robots cannot enter the buildingand tread its way through the maze of the machinery without creating furtherdamage. 19 MES College of Engineering, Kuttippuram
  20. 20. Robots In Radioactive Environments Seminar2004 If the installation is fitted with fractal robots, they can kick into actionseconds after an accident even if they are damaged because they are self repairingmachines. The first priority of the robots is to negotiate the rough terrain andarrive at the accident scene. Operators are used to shuffle the bricking positionaided by computer software that calculates deformation algorithms and routes formoving cubes to cope in undefined terrain.7.2 Negotiating Undefined Terrain Using a True Multi-terrain Vehicle The fractal robots squeeze through small holes by shuffling the bricksaround. They take with them cameras, lighting and any other special equipmentintegrated into the cubes and which can squeeze through the available holes.Under operator control, the fractal robots can then install lighting and cameras.Dust suction equipment and/or hoses can be installed to filter out dust and fumes.The robotic cubes can be used as structural supports to support collapsingceilings. Terrain that is not a problem for the robotic cubes which can transforminto foot units that allow the machine to support itself whilst negotiating hallwaysand corridors. The possibility of malfunction of electronic systems is avoidedusing lead shielding and using specialized robotic cubes that have no electronicsand have the equivalent of a mechanical computer inside it built out of relays.7.3 Reactor Core Melt Down Fractal robots can handle the worst case reactor core meltdown accident. Ifthe reactor is eating its way through the ground as happened in Chernobyl, we canstop it. The problem with such a reactor is that in the molten state it is hot andcorrosive. The melt cannot be cooled with normal fluids as they can be vaporisedby the heat generated by radioactive molten core which will continue to generateheat for days if not weeks. The molten core has to cool by the equivalent of anuclear coolant such as molten lead. By amalgamating the molten lead with 20 MES College of Engineering, Kuttippuram
  21. 21. Robots In Radioactive Environments Seminar2004molten core, the nuclear reactions are shut down. Whatever the coolant used,actions has to be taken immediately if the molten core is not to eat its waythrough all the reactor building floors and seep into the ground from where it canbe very difficult to extract.7.4 Power Station Design of The Future Fractal robots are competitive when the full nuclear power productioncycle is taken into account. This includes decommissioning work which is nowestimated to run into billions of dollars per installation. Fractal robots are alsocompetitive in the disposal of radio active wastes. It is not possible to simply taketons of equipment and bury it somewhere with out due attention and care to thepossibilities of radioactive substances leeching into the environment over thedecades. Fractal robots can help in a number of ways to reduce the amount ofwaste generated and to look after those wastes. For example, if much of the low activity structure is made of fractal robotcompatible structures, then they can be recycled in other installations or even inthe current installations in more radioactive areas as they acquire higher andhigher dosages until they end up in the reactor room as reactor supports andlining. Instead of commissioning more new installations which will then getcontaminated, the old structures from the old reactors are de-installed and reusedin the newer installations to acquire a higher dosage. Fractal robots give hundredpercent automation and thus there is no need for humans to go into reactor areasor contaminated areas for any reasons for this type of reactor. With the level of automation offered by fractal robots, when new reactorsare commissioned, the old structures that have been de-commissioned areretrieved from storage and reused. This recycling minimizes creation of nuclearcontaminated wastes. De-commissioning can also be carried out using same 21 MES College of Engineering, Kuttippuram
  22. 22. Robots In Radioactive Environments Seminar2004robots. De-commissioned robotic parts held in storage can be looked after bymore fractal robots patrolling, the waste site with sensors to look for leaks andleeching. CHAPTER 8 CONCLUSION Over the years, several telerobotic systems for periodic maintenanceservices and unforeseen interventions have been developed. Most of the processthat is inaccessible to human has been automated. Thanks to the design ofreference software architectures for teleoperated systems, it has been possible todevelop different applications reusing existing components. But even after all these developments, complete automation still remains achallenge. It’s believed that complete automation would be possible with thedevelopment of fractal robots. 22 MES College of Engineering, Kuttippuram
  23. 23. Robots In Radioactive Environments Seminar2004 REFERENCES 1. Keramas James G., “Introduction to Robots” ; McGraw-Hill 2. Kim, S; Jung, S.H.; Kim, C.H. , “Preventive Maintenance and Remote Inspection of Nuclear Power Plants Using Telerobotics” IEEE 1999. 3. Alvarez, B.; Iborra, A.; Alonso, A.; de la Puente, J.A.; Pastor, J.A.; “Developing Multi-application Remote Systems”,Nuclear Engineering Int. vol 45, March 2000. 4. Pastor, J.A.; Alvarez B.; Iborra, A.; Fernandez, J.M.: “An Underwater Teleoperated Vehicle for Inspection and Retrieving”,1st Intl. Symposium; Brussels ,November 1998. 5. Iborra, A; Alvarez, B.; Navarro, P.J.; Fernandez, J.M.; Pastor, J.A: “Robotized System for Retrieving Fallen Objects Within the Reactor Vessel of a Nuclear Power Plant”,Intl.Symposium, Industrial Electronics, Mexico; IEEE 2000. 23 MES College of Engineering, Kuttippuram
  24. 24. Robots In Radioactive Environments Seminar2004 24 MES College of Engineering, Kuttippuram