Visual Beam Tube Inspection Visual Beam Tube Inspection at the TRIGA Reactor Viennaat the TRIGA Reactor Vienna

by by H.BH.Bööckck, , A.MusilekA.Musilek, , M.VillaM.Villa, ,

University of Technology Vienna/University of Technology Vienna/AtominstitutAtominstitut

presented by Mario Palombapresented by Mario Palomba

Helmuth BöckVienna University of Technology, Atominstitut of the Austrian UniversitiesStadionallee 2, 1020 Vienna, Austriaph: ++43-1-58801 14168fax: ++43-1-58801 14199boeck@ati.ac.at

Development of Safeguards Instrumentation

Prevention of Illicit Trafficking

Calibration of Nuclear Instrumentation

Irradiation and Test of Safeguards Instrumentation

Storage of Special Nuclear Material

Training courses for Junior Inspectors (more than 120 trained)

Since 1992 more than 100 IAEA fellows from developing countries

ClosestClosest NuclearNuclear FacilityFacility to to thethe IAEAIAEA

ATI

Downtown

IAEA (VIC)

TheThe TRIGA Mark II TRIGA Mark II ReactorReactor ViennaVienna

is the only operating research reactor and the only nuclear facility in Austria

uniquely used for training and education of students and junior professionals in the fields of

Nuclear Technology

Neutron and Solid State Physics

Radiochemistry

Radiation Protection and Dosimetry

Low Temperature Physics

Nuclear- and Nuclear Astrophysics

Electron- and X-ray Physics

General General AspectsAspects

Pool type reactor

For training, research and education

Steady state and transient operation

Simple in design

Cheap in operational costs

1. Reactor

Fuel-Moderator Material 8.5 wt% uranium89.9 wt% zirconium1.6 wt% hydrogen

Uranium enrichment 19.8 % uranium-235Active core volume 49.5 cm diameter

38.1 cm highCore loading 81 fuel elements, Amount of U-235 per element approx. 38 gramsReflector graphiteReactor control 2 motordriven control rods

1 pneumatic control rod materialprompt negative temperature

coefficient of the fuel

Main technical Data of the TRIGA Main technical Data of the TRIGA MarkMark--II Reactor Vienna (1)II Reactor Vienna (1)

2. Steady state reactor operation mode

Maximum thermal power 250 kWMaximum thermal neutron flux density 1x1013cm-2s-1

Maximum fuel temperature 220°CMaximum primary water temperature 35°C

3. Transient reactor operation mode

Peak power thermal 250 MWIntegrated energy production 12 MWsTotal duration of power pulse 40 msMinimum reactor period 10 msMaximum fuel temperature 360°C

Main technical Data of the TRIGA Main technical Data of the TRIGA MarkMark--II Reactor Vienna (2)II Reactor Vienna (2)

Beam Tube InspectionsBeam Tube Inspections

Of the four TRIGA beam tubes (A,B,C,D) the beam tubes B and C have been visually inspected in 1985

Due to collimator rearrangements the remaining beam tubes A and D were made accessible in summer 2005

Prior to the inspection the reactor was shut down for 3 weeks

The fuel elements around the beam tubes were removed

Stainless steel dummy elements were inserted in the fuel positions to shield the core radiation

Totally 5 men were involved for one week for each beam tube to carry out the beam tube inspection

Tube D

Neutron scattering

Tube A

Fast rabbit system

Beam Tube ABeam Tube A

Disassembling the Fast PneumaticRabbit System

View into the beamtube, part of theshielding is seenincluding the transfer tubes (left and top)

Disassembling the ShieldingDisassembling the Shielding

Problem was solvedusing some special tools

Temporary Problems due to a Stuck Shielding DeviceTemporary Problems due to a Stuck Shielding Device

Beam Tube Loading DeviceBeam Tube Loading Device

Position holes for the beam tube loading device were filled with debris and had to be cleaned

Transport of Fast Rabbit Transport of Fast Rabbit System to an interim StorageSystem to an interim Storage

The active part of the PTS was removed into the beam tube loading device and transferred to an interim storage: Front dose rate approx. 50 mSv/h

View into the View into the Piercing Beam Piercing Beam

Tube ATube A

Generally the beam tube was very clean, last inspection about 30 years ago, a 1 cm cut was observed at the beam tube front end

Inspection ToolsInspection Tools

A rigid endoscope was used to check the beam tube’s inner surface using a 90 degree deflection objective and photo- and video equipment

Direct dose rate in front of the beam tube about 30 mSv/h

Inspection of Beam Tube AInspection of Beam Tube A

The video signal was directly transferred and recorded on a Laptop

Vacuum Cleaning the Beam TubeVacuum Cleaning the Beam Tube

Finally the beam tube was vacuum cleaned

Replacement of Fast Rabbit Replacement of Fast Rabbit SystemSystem

with Inner Beam Plugwith Inner Beam Plug

A standard TRIGA beam plug was used to fill the empty beam tube and to reduce the dose rate during operation

Preliminary Work for Preliminary Work for Inspection ofInspection ofBeam Tube DBeam Tube D

(Radial Beam Tube)(Radial Beam Tube)

Disassembling experiment equipment in front of the beam port

Corroded Shielding Tank Corroded Shielding Tank using Boric Acidusing Boric Acid

Unnoticed during operation a shielding tank containing Boric acid leaked and part of the liquid was distributed on the floor behind the shielding construction

Wooden CollimatorWooden Collimator

A wooden collimator partially disintegrating due to extreme temperature was removed from beam tube D

Final Inspection and Final Inspection and Cleaning of the Radial Beam Cleaning of the Radial Beam

Tube DTube D

Same inspection procedure as for beam tube A

Beam tubes are usually inaccessible for a Beam tubes are usually inaccessible for a long period due to experimental installationslong period due to experimental installationsAny occasion of changes in beam tube Any occasion of changes in beam tube

installations should be used for a visual installations should be used for a visual inspectioninspectionEspecially humidity, water leakage and/or Especially humidity, water leakage and/or

corrosion are dangerous indicators corrosion are dangerous indicators Reproducible documentation of each Reproducible documentation of each

inspection should be carried out especially of inspection should be carried out especially of any visible defects for later comparisonany visible defects for later comparison

ConclusionConclusion