Post on 03-May-2018
Table of contents
� 1. Nuclear security in France
• Regulatory framework
• Provision related to measurement
� 2. Non Destructive Assay: description of the techniques used
• Passive neutron measurement
• Gamma spectrometry measurement
� 3. Examples
1. Nuclear security in France: regulatory framework
Defense CodeL1332 L1333
Security of installationsof vital importance
Protection and controlof nuclear materials
SAIV Decree PCMNIT Decree
10 Orders4 Orders DNS
VIGIPIRATEPlan
SAIV: Activity Sector of Vital ImportanceDNS: National Security Directive
Pillars of the protection and control of nuclear materials
Nuclear Materials protection in facilities is based on three complementary independent layers
� 1 - Physical protection
Provisions aimed at preventing, detecting or delaying any unauthorized or unjustified access to the nuclear materials and any unjustified movement of these materials out of the zones where they should be located. These provisions include alert procedures allowing for intervention of response forces.
Pillars of the protection and control of nuclear materials
� 2 - Physical follow-up
Provisions aimed at authorizing nuclear material movements and controlling nuclear material when necessary in order to detect any attempt of fraud when moving material. They are based on a permanent and precise (quantity and quality) knowledge of all the entries /exits of nuclear materials and on the knowledge of their location, their use, their movements and transformations.
� 3 – Nuclear Material accounting
Provisions for data control performed independently of physical follow-up / tracking systems. Accounting provisions are based on the daily knowledge of the book inventory in every material balance area (MBA), and on the variations of this inventory, especially entries and exits.
Provision related to measurement
Defense Code - Art. R. 1333-11…
� 1/ Always know the exact quantity and quality, all inputs and outputs of nuclear material in facility or installation"
� 2/ To monitor the nuclear material present in facility in order to know their location, use, movement and transformation"
The objectives of measuring nuclear materialfor the operator
� Control at entry => detection of difference
� Characterization => knowledge
� Internal controls => detection of difference
� Control before shipping => detection of difference
� To acquire knowledge
� Quantitative and qualitative measurement
� As soon as integrity of an article is modified
� => Continuity of the follow-up
� In any event: before shipping
Inspections by the Ministry in charge of energy with the help of the IRSN
� Annual program
� Aim at verifying operators obligations and commitments.
� Inspections can be :– Routine inspections
– Comprehensive inspections or focused on specific themes
– Reactive (following an event)
� Control operations performed during inspections :– are conducted independently by sworn and accredited inspectors
– are conducted on-field
– concern technical provisions and organization
– can imply independent measurements (NDA)
– are second level controls
– are not aimed to be exhaustive
Inspections including independent measurement
� Objective 1: control of implementation of commitments - refering to the documentary reference framework - for the detection of discrepancy on the authorized movements
� Objective 2: control of quality and quantity of nuclear material – within the uncertainties described in the documentary reference framework
� Verification of operators declarations, using independent methods
� Inventory verification– in addition to check tags
– rapid measures on many items
� Precise control of the quantities of nuclear material– non-destructive measurements on a limited number of articles
• mass of uranium, plutonium, thorium
• U and Pu isotopic composition
Measuring the isotopic composition of natural uranium by different techniques
0
0.2
0.4
0.6
0.8
1
1.2
gamma spectrometry gamma spectrometry alpha spectrometry mass spectrometry
enrichment (%
)
15 mn 2 h 5 d 10 d
Inspections including independent measurement
� Constraints
– Non destructive Assay
– Quick measurement
� Means : realization of NDA measurement by inspectors from IRSN, in the operator plant
– Passive neutron measurements
– Gamma spectrometry
– Weighting
� Qualitative and quantitative measurement
Description of a typical inspection
Preparation meeting
S M T W T F S
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
S M T W T F S
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Packaging
Measurement (4+1 days)
Packaging, Conclusion meeting
TransportReport
, Transport , Setting , Sampling
Announced inspection
Inspection with current devices (~ 23)
PLUMFUNEHOTRANSINSPECTORFRAMJCC51AMATHORTHEMIS…
Feedback from the field
Research and development
Request for a new inspection
New devices
Link between R&D and inspections
2. Non destructive assay: description of the techniques used
� Passive neutron measurement
� Gamma spectrometry measurement
Passive neutron measurement
� Measure neutrons emitted naturally by the nuclear material
� The total mass of plutonium contributes to the measure because the neutrons easily penetrate the nuclear material
� Therefore a measure of high masses is possible
� No spectrometry (simply counting)
� Requires knowledge of the isotopic composition
Gamma spectrometry measurement
� characteristic gamma-rays of the isotopes
� identification
� Intensity of the gamma-ray
� proportional to the mass of isotope
Computer with software acquisition and processing of spectrum
Analyser Detector Sampleto characterize
Quantitative measures: parameters to be considered
� Background
� Efficiency of the detector
� Distance of measurement
� Screen between source and detector
� Self-absorption
� Nuclear data
BkGcefficiencyfcactivityfn screenectorabsorptionselfsource −××==
− )()),((
system detection theby detected count of Number n
det
Energy (keV)
Nombre de coups 185,7 keV
Pic caract é ristique
de l ’uranium 235
de surface Si
Number of counts
Energy (keV)
185,7 keV
Characteristic gamma-rayfor U-235
i
3. Examples
� Check of waste containing nuclear material (plutonium)
– 2 measurements devices: FUNE and PLUM
� Search for biases
– quantitative uranium measurements with improper consideration by the operator of self-absorption processes for a uranium mass measuring system, leading to under-estimating declared amounts of nuclear material.
– the use of contradictory measuring system allows showing biases in the operator’s measuring, as the search for such biases based on a review of the operator’s practices alone is often difficult.
Check of waste containing nuclear material (plutonium)
� Kind of Waste
– Low active plutonium waste drum
– 100-liter/200-liter drum
– ~ 30 kg
– Light matrix: combustible, metallic
� Range of measurement
– [50 mg - 100 g] of plutonium
Strategy to declare an anomaly (1)
� Two results are obtained for each drum :
1. FUNE result (~30 min)
2. PLUM result (~30 min)
+ the declared value
� How to compare them to the declared value?
� What happens if they are different?
� What criteria to use?
Strategy to declare an anomaly (2)
Several cases…
Declared value
PLUM value (γγγγ)
FUNE value (n)
« Good »case
Anomaly
?
Strategy to declare an anomaly (3)
Several cases… -> interest of complementary methods
Declared value
PLUM value (γγγγ)
FUNE value (n)
« Good »case
high self-absorption ?Presence of other neutron emitters(ex: Curium)
In summary
� The nuclear security regulation provides
– physical protection, follow-up, and accoutancy
– Shipper / receiver protocols
• "first level“ control
• "second level“ control
– Periodic physical inventories
– Realization of measures:
• to acquire knowledge
• Continuity of the follow-up
� The holder of nuclear material should always know the qualities and quantities of nuclear material held
For the operator
In summary
� Measurement done in nuclear facilities by national control inspectors
� Control of implementation of commitments - refering to the the documentary reference framework - for the detection of discrepancy on the authorized movements
� Control of quality and quantity of nuclear material – within the uncertainties described in the documentary reference framework
� Common methods used rely on passive neutron measurement techniques and gamma spectrometry.
� Enables to ensure the credibility of the control in full independence from operators.
Inspections including independent measurement