Nuclear Technology and Innovation
Ing. Tomáš Grísa NUVIA a.s.
NUVIA - decommissioning Free Release Measurement Facility
Nuclear Technology and Innovation 2
NUVIA Czech / Radioactive Waste Measurement
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NUVIA Czech / Radioactive Waste Measurement
• Development, production, supply, implementation and technical support of
measuring systems for:
• Ionizing radiation monitoring and control, Radioactive waste classification and assay
• Radiological characterization of the nuclear equipment, components and buildings
before decommissioning
• Characterization of all radwaste from Dukovany and Temelin NPPs (the
only Czech company authorized by State Office for Nuclear Safety and
Czech Metrology Institute for provision of free release measurement of
RW)
• Measuring systems and spectrometric SW for RW characterization and
FRM (incl. preparation for decommissioning)
• FRM - gamma spectrometry measurement of potentially radioactive materials before
their release into the environment (incl. nonstandard forms)
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EMRP Projects
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EMRP Projects
• EMRP JRP ENV09 – Metrology for Radioactive Waste Management
(Metro RMW)
• 1. 10. 2011 – 30. 9. 2014
• 7 work packages
• Experimental facility built in NRI Řež
• EMRP JRP ENV54 – Metrology for Decommissioning Nuclear Facilities
(MetroDecom)
• 1. 10. 2014 – 30. 8. 2017
• 7 work packages
• Implementation of free Release measurement facility on decommissioning site (JRC
Ispra)
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Clearance levels
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Clearance levels in Czech Republic
• Mass and surface activity divided into 4 groups:
• It is impossible to measure each kg of material separately. Assumptions
enabling averaging of activity must be accepted!
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Clearance levels in Czech Republic
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Free Release Measurement Facility „SuperMUM“
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FRMF „SuperMUM“
• New generation of FRMF – „SuperMUM“
• Measuring of waste in boxes (2 types) and 220l drums + universal holder
• Installation in ISPRA (2016)
• 4 HPGe detectors
• 4 plastics detectors & SCA4 (NUVIA) – experimental setup for
segregation facility
• 3 neutron detectors – experimental setup of JRC Ispra
• GAMWIN SW for gamma spectrum analysis
• Low background natural shielding bricks
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FRMF „SuperMUM“ – 3D overview
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FRMF „SuperMUM“ – Installation in Ispra
Loading conveyor
Unloading conveyor
Safety sensors
Measuring chamber
Cabinet with Electronics
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Principle of measurement
• Material is loaded in the box
• The box is put on the loading conveyor
• Operator enters required data
• Material is weighted
• The box is moved into the chamber
• Spectra are acquired at 3 positions
• The box is moved to the unloading conveyor
• Spectra are analyzed
• Results are displayed and saved
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Measurement chamber
Lead collimator
Box with material
IDM module
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IDM – Interchangeable Detector Module
• HPGe detector (85 mm diameter × 30 mm deep) – 50% rel. eff.
• Mechanical Stirling cooler
• MCA – Digital Signal Processing (DSP)
• Integrated High Voltage supply
• USB connection
• Identical efficiency
Lead shielding
collimator
Detector top MCNP
model
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FRMF „SuperMUM“ – Neutron detectors
Neutron detectors
• JRC experimental setup
• Passive neutron counting
• He3 detectors
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FRMF „SuperMUM“ – Plastic scintillators
Plastic scintillators
• Implemented to FRMF as an
experimental setup
• Proof of concept for segregation
facility (fast scan of material)
• Material is measured for total
gamma counts
• 4 x 5l plastic scintillators – high
absolute efficiency
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Free Release Measurement Facility - Shielding
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NuRAD – Special shielding bricks
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NuRAD – Special shielding bricks
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NuRAD – Special shielding bricks
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
0 0.5 1 1.5 2 2.5
Bac
kgro
un
d c
ou
nt
rate
[cp
s]
Energy [MeV]
Background without shielding Background with shielding
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Free Release Measurement Facility - Software and
algorithms
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Software components
• Measurement and analysis module –
measurement, communication with HW (MCA,
PLC etc.), spectra acquisition and analysis
• Operator module with GUI – control and
visualization, interface for users
• Database – data storage
• Application server – interface for other parts of
system and external systems, web based
application
Web Client Application server
Database
Measuring and
communication
module for FRMF
Client module for
FRMF
Gamma
spectrometric
system
MCA PLC
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Software – Client application
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Algorithms
I. Input parameters (entered by user)
• Measurement geometry (1, 2 or 3 positions)
• Measurement time
• Material type (steel, aluminum, plastic …)
• Box type
• Filling of box in percent (level)
• Note, description or batch ID
II. Weighing
• Reading gross weight on input conveyor
• Calculating net weight and density of material
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Algorithms
III. Spectra acquisition
• HV check
• Detector temperature check
• 4 detectors x 3 positions = 12 spectra files
• All spectra are saved
IV. Searching for hot-spots
• Each spectrum is divided into regions
• Hypothesis test, that CPS (corrected for different efficiency of each spectra due to different geometry –
different segment of the box) in given region are same in all spectra files
• If the hypothesis is rejected, material is said not to be homogeneous
• Results displayed for operator
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Algorithms
V. Sum spectrum
• Done only for homogeneous
material (for lower detection limit)
• If hot-spot is found all spectra are
analyzed individually
• Precise energy calibration (identical
FWHM for single and sum spectra)
Single spectrum
Sum spectrum of 12 individual spectra
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Algorithms
VI. Efficiency calibration (sum or individual spectrum)
• Eff. file used for actual material, density, filling, container type and geometry (1-3 positions)
• All efficiencies (calibrations) calculated by CMI
• Model verified by comparison with measurement of reference materials
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Algorithms
VII. Analysis of spectrum
• Limited nuclide library, based on ROI analysis (expected
nuclides)
• Wide nuclide library, based on peak search
• Activity/MDA calculated
• Raw reports generated
• Results are combined together (greater value selected)
VIII. Scale factors
• Read from customer DB
• Hard-to measure nuclides are calculated and added to
results
IX. Release coefficient calculation
• Comparison with limits
X. Reporting and displaying results to user
XI. Saving to DB
• All data and files are saved to DB using WS (Web Services)
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Software – Web based application
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Free Release Measurement Facility – Reference materials
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Reference materials
• Phantoms (steel & plastic balls)
• Reference materials (gravel, clay, steel tubes)
Steel balls each 100 Bq of Cs-137
Plastic ball
Gravel
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Reference materials
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Monte Carlo calculations
• Monte Carlo calculations in cooperation with CMI (HPGe detectors and plastic
scintillators)
• Optimization of number and dimensions of detectors
35 Nuclear Technology and Innovation
Ing. Tomáš Grísa
+420 724 901 015
www.nuvia.cz
Contact