NORM in Scrap Metal...
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T h e R T D G r o u p NORM in Scrap Metal... Richard van Sonsbeek Röntgen Technische Dienst bv Dept. Radiation Protection Services P.O. Box 10065 3004 AB Rotterdam The Netherlands Phone +31 (0)10 2088229 Fax: +31 (0)10 4158022 e-mail: [email protected]
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NORM in Scrap Metal. Richard van Sonsbeek Röntgen Technische Dienst bv Dept. Radiation Protection Services P.O. Box 10065 3004 AB Rotterdam The Netherlands Phone +31 (0)10 2088229 Fax: +31 (0)10 4158022 e-mail: [email protected]. The Dutch approach. - PowerPoint PPT Presentation
Transcript of NORM in Scrap Metal...
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NORM in Scrap Metal...
Richard van SonsbeekRöntgen Technische Dienst bv
Dept. Radiation Protection Services
P.O. Box 10065
3004 AB Rotterdam
The Netherlands
Phone +31 (0)10 2088229
Fax: +31 (0)10 4158022
e-mail: [email protected]
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The Dutch approach
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Melting radioactive material with scrap metal
Health risk for workers and public (neighbours, users of products)
Contamination of foundries and the environment
Financial consequence for company that is held liable
Especially with strong artificial sources
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Measures to avoid risks
Adding clauses in contracts stating that loads of scrap metal should be free of radioactive materials
Check incoming loads of scrap metal for radioactive materials: portal detectors, crane detectors, portable detectors
Same precautions are taken by the (bigger) scrap metal traders
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Portal detector
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Legal framework
Dutch Nuclear Energy act: It is prohibited to possess, use, import, export, or dispose of radioactive substances without a license;
Suspicion to be in possession of radioactive substances without a license must be reported to the relevant authorities, i.e. VROM Inspectie, the Dutch Inspectorate for the environment
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Radiation Protection Ordinance
Exemption, and clearance levels per radionuclide in terms of activity concentration, and total activity;
Summation rules for mixtures; Distinction between practices
(artificial sources), and work activities (sources of natural origin, i.e. NORM)
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Work activities
Two limits for activity concentration One below which the radioactive
substance is exempted from the regulations;
Another one, that is ten times higher, below which “only” reporting of the work activity is required;
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Limits for work activities
Activity concentration(Bq/g)
Radionuclidea
limit forreporting
limit forlicense
Activity (Bq)
Pb-210+ 110+2 110+3 110+4
Ra-226+ 1 110+1 110+4
Ra-228+ 1 110+1 110+5
Th-228+ 1 110+1 110+4
Th-232sec 1 110+1 110+3
U-238sec 1 110+1 110+3
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Guideline for Metal Recycling Industry
First version drawn up in 1997 After three revisions, and following
the publication of the decree on radioactively contaminated scrap (January 2003), a completely new guideline has been published by VROM Inspectie.
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Advice in guideline
Perform measurements on each incoming load of scrap with appropriate radiation detection equipment, and by sufficiently trained personnel
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Further investigation to be performed by the trader
background radiation level; maximum dose rate; extent, and shape of the radiation field; origin, destination, transport company,
weight quality, and description of the load
If dose rate > 20 Sv/h or 200 times background: report directly to VROM Inspectie, and keep at a distance.
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Report to VROM Inspectie
Result of the further investigation Scrap Metal trader shall propose a
Solution
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Two possible solutions
Return container to sender without opening it.
Have load inspected, and sorted out
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Returning load to sender Only permitted if the maximum dose
rate is smaller than 5 Sv/h; No suspicion that the load contains a
single concentrated source; Declaration by sender that he will
take back the load, and proof thereof; Permission from VROM Inspectie A Dutch sender always has to have
the load inspected, and sorted
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Inspection, and sorting
Expert company with license (RTD) Plan of action must be approved by
VROM Inspectie
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Plan of Action: preparation
Radiation expert, minimum level 3 with sufficient experience
Appropriate radiation detection-, and personal protection equipment
Packing material Shielding material (if necessary) Transport container
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Plan of action: steps
Perform radiation measurements on the outside of container
Give instruction to assistants Put on Personal Protection
Equipment Unload container in controlled way
on liquid proof floor Check every batch that is unloaded Isolate radioactive objects
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Analysis of radioactive objects
Dose rate measurements Contamination measurements Take Samples Take Pictures Record marks
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Final actions Pack radioactive objects or prevent
radioactive material to disseminate Store radioactive objects on location,
with appropriate instruction to the customer, or
Transport radioactive objects for further analysis, or storage at RTD’s premises
Check used equipment, floor, and container for contamination
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Report Details of load Plan of Action Involved persons Used equipment Dose rates measured Contamination measured Result of laboratory analysis Dose to persons, and environment Conclusion, and advice
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Treatment of isolated radioactive objects -1
Return to an original sender outside the Netherlands (transport regulations, international procedures, permission from VROM Inspectie, declarations from the sender)
Re-use of the objects after decontamination by a licensed company, e.g. Reym
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Treatment of isolated radioactive objects -2
Process the objects at Siempelkamp (Krefeld, Germany), if the criteria set by this company are met;
Dispose of the objects as radioactive waste directly to COVRA, the Central Organisation for Radioactive Waste in the Netherlands
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Number of incident reports
Portal detectors are very sensitive Portal detectors do not distinguish
between artificial radioactive sources and other radioactive material
Lot of radioactive objects are intercepted that otherwise would not have been noticed, e.g NORM contaminated objects
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Summary of incidents1996-2002
1,497 reports to VROM Inspectie, of which
892 reports (60%) concerned loads of scrap metal
The last figure includes “false alarms”
Most inspections have been performed by radiation experts of RTD
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Trends
Number of reports on loads of scrap metal increased almost monotonously from 39 in 1996 to 208 in 2002, and is still increasing;
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Maximum dose received by radiation expert
Average effective dose roughly estimated to be maximum 25 Sv per job (10 Sv due to external irradiation, and 15 Sv due to internal contamination)
Total dose received by radiation expert < 0,25 mSv/year (also due to other radiological work)
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NORM in scrap metal
In 2001, and 2002, about 70% of the reports on loads of scrap metal, concerned NORM contaminated objects;
About 25% to 35% of these reports concerned objects containing radioactive slag-wool
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Contaminated beer barrels
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Information on beer barrels
Load originated from Turkey; 28 contaminated barrels between
other contaminated objects; max. dose rate on surface of barrel:
6.5 Sv/h; It was decided to make an x-ray
before opening one of the Barrels
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X-ray of one beer barrel
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Content beer barrel
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Results
Cans contained Ra-226 scale with an activity concentration of 131 Bq/g;
Wilful action to illegally dispose of radioactive material and / or harm a competitor;
The barrels were processed at Siempelkamp
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Conclusion -1
In the Netherlands a method has been developed in which loads of scrap metal are inspected, and sorted out safely;
Radiation dose received by workers, and general public due to radioactively contaminated loads has been very limited;
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Conclusion -2
The chance that radioactively contaminated scrap metal is intercepted has become higher:
More portal detectors (at the end of 2002 at least 66 companies have installed one or more)
Introduction of crane detectors
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Decree on radioactively contaminated scrap
Obligation to perform measurements, and keep registry of these measurements;
Obligation to train personnel
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Test protocol Portal detectors
In a separate regulation the minimum requirements for radiation detection equipment are stated.
RTD performed inter-comparison measurements on 32 portal detectors
All, or almost all fulfil the requirements for sensitivity, i.e. to be able to detect a Co-60 source that causes a dose rate of 20 nSv/h
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Training of personnel
Currently the training provided by RTD is the only one that is acknowledged by the Dutch authorities
Up to an including April 2004, about 100 employees of scrap metal traders followed our one day course on radiation protection
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That’s all folks!!!
