MANIPULATOR-DEPLOYED SYSTEMS FOR SURFACE

DECONTAMINATION IN NUCLEAR FACILITIES

Jan Bremmer, Sascha Gentes and Nadine Gabor

Karlsruhe Institute of Technology (KIT), Institute for Technology and Management in Construction (TMB)

Technology and Management for the Decommissioning of Nuclear Facilities

Am Fasanengarten, Geb. 50.31, 76131 Karlsruhe, Germany

Keywords: AMANDA, MANOLA, Manipulator, Vacuum Technology, CompactRIO.

Abstract: Due to the phasing out of nuclear energy in Germany there are a growing number of nuclear facilities that

have to be decommissioned within the next years. In this context a multitude of surfaces in nuclear facilities

have to be decontaminated. Manipulator-deployed systems offer a suitable solution and are properly

designed for this kind of task. Beyond that they can be used for the processing of surfaces in civil as well as

industrial fields of application, e.g. the stripping of coatings on metal surfaces. By the use of a suitable

supporting system various attachments like a milling machine or laser can be carried and operated on walls

and ceilings. Vacuum suction plates guarantee the interconnection between the supporting system and the

object to be treated. Due to the intricate processes as well as the required flexibility arising from the multi

purpose use with milling or laser attachments a robust control system with a high performance and a high

level of customization is required. The following article introduces to you the systems in detail.

1 INTRODUCTION

Due to the phasing out of nuclear energy in

Germany there are a growing number of nuclear

facilities that have to be decommissioned within the

next years. In order to successfully dismantle and

decommission these facilities a great amount and

variety of processes and actions is required.

Among other things these include the qualified

decontamination of surfaces. The associated tasks

are manifold, ranging from simple cleaning to

complete surface ablation. The latter is particularly

challenging due to the multitude of surfaces in

nuclear facilities that have to be decontaminated.

In this regard, effectiveness and economic

efficiency play an important role as well as the

avoidance of secondary waste and cross

contamination (Gentes, 2006: 416, 417). Therefore

the selection of an appropriate process and system is

crucial.

But only a few of the currently available

processes for the decontamination of surfaces fully

meet the required criteria and are applicable for this

kind of task. Therefore the nuclear industry calls for

more suitable and efficient decommissioning

technologies.

The Institute of Technology and Management for

the Decommissioning of Nuclear Facilities at the

Karlsruhe Institute of Technology (KIT) has

addressed itself to this task and thus is conducting

research as well as is developing innovative

processes and machines for this kind of purpose. All

this is done in co-operation with industry partners

that are focused on carrying out decommissioning

activities in the field. This kind of co-operation helps

to generate feedback in order to improve the

machines.

2 THE BASIC IDEA

The decontamination of surfaces in nuclear facilities

is an intricate and time consuming process. It is very

labour intensive, because most techniques are hand-

operated or difficult to handle by just one person.

Compared to the output of a machine the

performance of labour is very low. Thus more labour

is required in order to be cost-effective.

Furthermore the timeframe for works conducted

in the hot zone, which is the controlled area inside of

a nuclear facility, is very limited per worker and

377

Bremmer J., Gentes S. and Gabor N. (2010).

MANIPULATOR-DEPLOYED SYSTEMS FOR SURFACE DECONTAMINATION IN NUCLEAR FACILITIES.

In Proceedings of the 7th International Conference on Informatics in Control, Automation and Robotics, pages 377-381

DOI: 10.5220/0002941403770381

 SciTePress

shift (HVBG, 2004: app. 2), due to the required use

of breathing apparatuses. Because of that several

teams have to be employed on alternating shifts to

ensure a proper exchange of labour which finally

results in a better practical performance.

Another important aspect is the high effort that

comes along with many of the techniques being used

for the decontamination of surfaces. In numerous

cases scaffolding is needed, especially in rooms with

big ceiling heights. Besides that extra time is

required for the set-up of equipment or machinery.

But the time spent on works preparation reduces the

overall period available for decontamination. Thus it

makes even suitable techniques less effective.

Based on these facts the idea was born to

construct and build a manipulator that is able to

climb on walls and ceilings autonomously, in order

to decontaminate surfaces by means of a milling

attachment or laser. The manipulator requires no

scaffolding or elaborate set-up. Besides that there is

only one operator needed to run the machine. Finally

the use of a manipulator results in a greater

economic efficiency.

3 MACHINE SPECIFICATIONS

Several requirements have to be met for the

successful decontamination of surfaces in nuclear

facilities. Besides the requirements requested by the

clients, e.g. regarding safety and economic

efficiency of the particular technique, there are

requirements that originate from the structural

conditions of a nuclear facility.

The relevant criteria have to be taken into

account when setting up a manipulator system.

Hence the following specifications have to be

implemented:

The manipulator is required to have a low self-

weight. This enables the operator to move the

system through the facility. In some cases the

support of a trolley might be useful.

Furthermore a modular layout allows the

operator to move the manipulator through small and

narrow openings by disassembling it partly.

In this case a low single-weight of each module

is essential to allow lifting them by one person only.

Moreover the disassembly as well as assembly of

the manipulator should be feasible in a very short

period of time. Therefore the use of quick fasteners

is recommended. The entire system has to be

flexible and rugged.

In order to meet the performance requirements

an output of at least 10 m

per hour is essential and

the minimum requirement of the clients.

Beyond that an autonomous operation of the

manipulator is advisable to keep the labour costs on

a low level.

Not less important are safety features that assure

a safe operation of the entire system. Here an

emergency shut-off is the minimum requirement.

But due to the fact that the manipulator can be

operated on walls and ceilings by means of vacuum

technology it is also a prerequisite to prevent the

system from falling off the object that is being

treated.

In this regard pressure monitoring and the use of

check valves is important.

Furthermore the control system needs a proper

set up that includes safety procedures.

4 MACHINE BUILD-UP

4.1 Basic System AMANDA I

According to the basic idea, a first manipulator

system was built in the course of the research project

AMANDA.

Figure 1: AMANDA I in wall operation.

AMANDA stands for Autonomous Manipulator

for Decontamination Assignments. The system can

be operated on walls and ceilings by using vacuum

technology. It is equipped with a milling attachment

for decontamination purposes.

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Figure 2: AMANDA I with control unit.

Figure 3: CPX Valve Terminal of AMANDA I.

The control unit which is shown in figure 2 is

based on a FESTO SPS. It is mounted in a switch

box underneath the control panel. The SPS is linked

with the CPX valve terminal on the manipulator via

cable. All pneumatic valves as well as all sensors for

the positioning of the pistons and for pressure

monitoring are connected to the CPX valve terminal.

The valve terminal is shown in figure 3.

In contrast to the valves and sensors, the servo

drive which moves the linear drive unit is directly

linked with the SPS by cable.

4.2 Successor System MANOLA

Based on the principle of the stand-alone

manipulator for decontamination assignments

AMANDA I the successor system MANOLA is

currently under construction at the KIT. MANOLA

is funded by the German Ministry for Education and

Research under the reference key 02S8548.

MANOLA stands for Manipulator Operated

Laser Ablation. The support system is operated with

vacuum technology as well. Instead of a milling

attachment MANOLA carries a laser system that is

used for the ablation of both, contaminated and

uncontaminated concrete surfaces and coatings.

MANOLA is built according to the specifications

listed in section 3.

To allow the transportation of MANOLA inside

of a nuclear facility the system is equipped with a

trolley. The trolley consists of an undercarriage

fitted with rubber tracks, and a loading platform.

Figure 2 shows a visualization of MANOLA in wall

operation. Beyond that, MANOLA can be operated

on ceilings as well.

Figure 4: MANOLA in wall operation.

5 MANOLA CONTROL UNIT

5.1 Processor And Chassis

The control unit of MANOLA is based on the

CompactRIO System that is distributed by National

Instruments. ‘National Instruments CompactRIO is a

small rugged industrial control and acquisition

system powered by reconfigurable I/O (RIO) FPGA

MANIPULATOR-DEPLOYED SYSTEMS FOR SURFACE DECONTAMINATION IN NUCLEAR FACILITIES

379

technology for ultrahigh performance and

customization. NI CompactRIO incorporates a real-

time processor and reconfigurable FPGA for reliable

stand-alone embedded or distributed applications,

and hot-swappable industrial I/O modules with built-

in signal conditioning for direct connection to

sensors and actuators’ (National Instruments, 2009).

The setup of the system applicable for

MANOLA consists of an embedded real-time

processor with 800 MHz, 512 MB DDR2 RAM, and

4 GB storage. The processor is connected to a 4-slot

Virtex-5 LX50 reconfigurable chassis that will be

installed on the MANOLA trolley. Furthermore two

8-slot deterministic chassis will be installed on the

manipulator itself for embedding all sensors and

actuators of MANOLA. Both chassis on the

manipulator will be linked with the main chassis on

the trolley in daisy chain mode via Ethernet cable,

and the main chassis on the trolley is linked via

WLAN with a laptop that serves as the MANOLA

Control Panel. Beyond all these components there

are WLAN cameras installed on each, the trolley and

the manipulator, for process monitoring by the

operator.

5.2 Sensors

Various sensors are part of the MANOLA control

system. They are used for different purposes like

positioning, vacuum and pressure monitoring,

position monitoring of pistons as well as scanning

and evaluating the object which has to be treated.

All sensors provide necessary input to the

manipulator for a proper operation.

First, there are four distance laser sensors used as

a simplified positioning system for MANOLA. The

four sensors are fixed to a traverse that carries the

laser processing head and runs over the main frame

of the manipulator. By moving the distance laser

sensors over the entire frame, many different reading

points can be generated and used to map the

borderlines given by adjacent parts of the building.

Second, a laser scanner is used for scanning and

evaluating the surface area of the object to be

treated. The laser scanner is part of the processing

head which also includes the optics of the laser unit

for the ablation process, and it enables the machine

to detect disruptive objects like offsets on the

surface, nails, screws, pipes, etc. All these different

kinds of objects may interfere with the operation of

the laser. Thus it is very important to detect them in

order to protect the laser processing head.

Third, there are two ultrasonic sensors attached

to the processing head. The ultrasonic sensors are

used for the detection of obstacles that may appear

in front of the processing head during treatment of

the surface area. In any case of interference the

process will be paused immediately in order to

protect the processing head. Then the processing

head will be moved up by an electric drive and the

suspect area will be scanned with the laser scanner if

applicable. Depending on the size of the obstacle the

manipulator will be moved forward or around the

localised object. The integrated decision making

process is based on the input of the various sensors

of the processing head.

Fourth, pressure and vacuum monitoring is an

essential part of the control system. Due to the fact

that the manipulator is operated with vacuum

technology it is security-relevant and prevents

MANOLA from falling off the wall. The vacuum for

the suction plates is produced by sending pressurized

air through vacuum generators that operate

according to the Venturi Principle. Because the

connection of the suction plates to the object

depends on the pressure as well as on the vacuum,

both, pressure and vacuum, need to be monitored.

Fifth, several small size sensors are required for

monitoring the exact positions of the pistons of all

pneumatic cylinders. Every time when a piston is

moved the control system asks for a feedback, if the

piston reached its destination. If this case is true,

further operations can proceed. In a false case,

further operations have to be put on hold due to the

occurrence of an error. Only after assessing and

removing the error by the operator further operation

may proceed.

5.3 Actuators

Besides the sensors MANOLA includes different

actuators. The actuators are used for the operation of

the supporting frame, the traverse and the processing

head. The actuators of MANOLA are a rack drive, a

rotary module, a servo drive as well as a couple of

pneumatic control valves.

The rack drive joins two important tasks. It

moves the traverse and processing head for ablation

processing as well as the supporting frame which

includes the main frame and sub frame for pacing.

By linking the rack drive to the component that has

to be moved only one drive is needed. Thus the

overall weight of the manipulator is kept on a low

level.

In order to turn the manipulator by 45, 90 or any

degrees to change the direction of processing a

rotary module is built-in to the center of the sub

frame. When the manipulator is rotated the suction

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plates of the main frame are released from the

object, e.g. a wall, and the rotary module can be

activated. After the manipulator is moved into its

final direction, the suction plates of the main frame

are sucked to the object again. During the whole

rotation process the suction plates of the sub frame

stay in contact with the object (wall, ceiling, etc.).

As described in the previous section, the

processing head is moved down for processing the

surface area and moved up when the processing is

paused or finished. Lifting and kneeling is executed

by a servo drive. Therefore the servo drive is

mounted between the outer end of the traverse and

the processing head. Input generated by the laser

scanner and the ultrasonic sensors provide necessary

input for the control system to actuate the servo

drive. Beyond that further input is provided via

control panel by the operator.

Last but not least a couple of pneumatic valves

are integral part of the pneumatic system and the

vacuum system. During pacing the relevant

pneumatic valves are activated. They control the

airflow necessary for the pneumatic cylinders and

the vacuum generators. Owing to the fact that the

pneumatic valves must not change their operating

status in case of a drop of voltage, bistable valves

are being used.

5.4 NI-Modules And Connectors

All actuators and sensors have to be linked with the

control unit. Due to the great variety of connector

types this requires an adaptable system. This is

implemented by using the cRIO-System with its

many different NI-Modules that all fit in the same

type of chassis. The cRIO chassis provides the

chance to build in the relevant type of NI-Modules

depending on the attachment and its relevant NI-

Modules.

Table 1: MANOLA NI-Modules.

Pos.

Module Connector Type Device

1 NI 9201 Analog IN Sensor

2 NI 9205 Analog IN Sensor

3 NI 9263 Analog OUT Actuator

4 NI 9421 Digital IN Sensor

5 NI 9425 Digital IN Sensor

6 NI 9472 Digital OUT Actuator

7 NI 9477 Digital OUT Actuator

8 NI 9853 CAN BUS Actuator

9 NI 9870 RS 232 Sensor

10 NI 9871 RS 485 Actuator

As quick as the attachment can be changed the

NI-Modules can be switched as well, even during

operation. That keeps the system flexible and

aligned with the customers needs. The following

table provides you an overview of all existing

connector types and the relevant NI-Modules.

6 CONCLUSIONS

Especially in areas where people are exposed to

great hazards, the use of a manipulator provides an

interesting solution. Nuclear facilities are one of

those fields of application. Beyond that there are

other areas as well where the use of a manipulator

can be valuable. For example this applies to high

structures that require costly scaffolding or other

areas that are difficult to access.

By providing a compact, light and robust unit

equipped with a milling attachment or laser, the

customer disposes of a suitable machine for the

treatment of various kinds of surfaces. Furthermore

the manipulator comes with an intelligent and

adaptable control system that provides a costumer

friendly operability as well as expandability.

Relating to feedback of project managers in

nuclear facilities under decommission, the use of

manipulators is more than welcome and thus will be

common in the future. The same is expected for

other fields of use. But in order to meet these needs

the current manipulator needs to be further

developed. Thus the system provides a platform

which is capable of being extended in the future.

REFERENCES

Gentes, S. (2006) Bautechnik 83, Heft 6:

Duennschichtiger Oberflächenabtrag von Beton in

kerntechnischen Anlagen, Berlin: Ernst & Sohn

HVBG (2004) BGR 190: Benutzung von

Atemschutzgeraeten, HVBG

National Instruments (2009) NI CompactRIO

Reconfigurable Control and Acquisition System,

[Online], Available: http://zone.ni.com/devzone/cda/

tut/p/id/2856 [05 Jan 2010]

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