ATRON
Accelerator of your ambitions





Arnaud Chapon (achapon@atron.fr)




Subsidiary of:
In partnership with:


  • Context
  • Calibration of radiation survey meters
  • Qualification of equipments and irradiation of materials

For our entities, the prevention concept is the implication for the reliability of the installations, the health-safety and the environmental protection

Context

2015:

  • Development by CERAP of a method for calibration of survey meters without a radioactive source,

2016:

  • Creation of ATRON to implement this breakthrough technology,

2018:

  • Start of operation of the platform and realization of the first irradiations.

Calibration of radiation survey meters

Calibration control of radiation survey meters:


  • According to French law (decree of October 23rd, 2020), periodicity of the calibration is three-year.

  • It consists in measuring the instrument characteristics supplied by its calibration certificate (established by the manufacturer before the first commissioning).

Method of calibration control of radiation survey meters usually implemented:


  • uses an irradiator containing several radioactive sources,

  • consists in verifying that the measured value of the instrument coincides with the expected dose rate of the source at a given distance and activity.
Example of an irradiator (CEA)
  • Cost of the sources and renewal:
    • three radioactive sources (137Cs),
    • to renew every 10 years.

  • Low productivity:
    • one radiation survey meter at a time,
    • necessity to move the radiation survey meters to cover the dose rate ranges.

  • Narrow energy range:
    • a single energy (662 keV).

Objectives of ATRON:

  • Develop a new calibration method of ionizing radiations measuring instruments on wide ranges of energies and dose rates,
  • Get rid of radioactive sources.

Envisaged way:

  • Use the braking rays of electrons accelerated at few MeV as the source of calibration.

Singletron 3.5 MeV HVE:


  • Accelerated electrons up to 3.5 MeV,

  • Conversion target
    ⇒ braking rays,

  • Variation of the beam current to cover the various dose rates,

  • Instruments at fixed positions.

Metrological advantages:


  • Extended energy spectrum adapted to the measuring range of the instruments (1.25 MeV, 2.00 MeV, 3.00 MeV),

  • Adaptation of dose rates (20%, 50%, 80%) to each H*(10) range of instruments.

Automaton of irradiation sequences:


  • Reliability ⇒ reduction of the risk of error,

  • Time saving ⇒ reduction of equipment downtime.

Environnemental advantages: No radioactive source.

Validated method:


  • Traceability of the connection of beam qualities to international references, quality assurance
  • +3000 instruments calibrated per year,
  • COFRAC accreditation n° 2-6778.

On-site maintenance of the instruments:


  • repair / adjustments, including contaminated instruments .

Site plan:

  • ∼700 m2 building,
  • Irradiation room / Accelerator room,
  • Maintenance workshop, reception/storage/expedition area,
  • Measurement and analysis laboratory for radiological samples ,
  • Offices, meeting room.

Implementation

Advantages:

  • Wide range of energy,
  • Dose rate ∝ beam intensity,
  • No radioactive source,
  • Possibility of automation.

Implementation:

  • Control of the accelerator:
    • accuracy and stability,
    • homogeneity.
  • Process fiabilisation:
    • reproductibility,
    • automation.
  • Traceability of the reference fields:
    • connecting, in terms of dose equivalent rate, to the national reference.

Development of a monitoring ionization chamber


  • Objective: regulate the accelerator current at low dose rates

  • Specifications:

    • specific measure at low levels of irradiation
      from 1 µSv/h to 15 mSv/h at 3 meters of the target
    • resistance to strong irradiations
      > 500 Gy/h
    • quick response time
      of the order of one second

Uniformisation of the irradiation field

Definition of a scanning function on the target

  • Dimensions of the target: 40x220 mm2
  • Vertical scanning: 1 kHz
  • Horizontal scanning: 25 Hz

Homogeneity of the irradiation field: up to 99,8% on +/-15°


Reproductibility of the instruments positioning

Design of an adapted samples carousel:

  • Rotating device,
  • Custom-made templates for every types of instruments,
  • Fixed camera where the instruments are put,
  • Reference ionization chambers placed in the field.
Carousel

Fiabilisation of the calibration process


  • Objective: automation of the irradiation sequences and establishment of calibration reports to reduce the risk of error

KERMA in air, Kair, cinetic energy transfered to the charged particules (Gy or J/kg): Kair=KC+KR
KC: At the electronical balance (compensation of the energy of charged particules entering and leaving the volume), KC=D; KR: Contribution of the braking rays

Measurement of the KERMA in air and associated uncertainty:

  • Transfert chamber developed by the CEA-LIST/LNHB

Conversion from Kair to H:

  • Spectrometric measurement of the irradiation fields,
  • Determination of the conversion coefficients hK such as H=hK.Kair

Calibration of radiation survey meters:

Comparison of the indication of the instrument
to the indication of the calibrated chamber

Reports edition:


QR codes associated with the status of the instruments
Example of metrology label
Example of report

COFRAC accreditation n° 2-6778:


  • Kerma in air rate (K)
    from 20 µGy/h to 440 mGy/h,
  • Ambiant equivalent dose rate (H*(10))
    from 25 µSv/h to 530 mSv/h,
  • Expanded relative uncertainty of 4.2 %.

Scope available on www.cofrac.fr

Irradiation of materials

FELIX accelerator

  • Electrostatic accelerator:
    continuous beam

  • Removable X target:
    possible irradiation in X or in e-

  • Dimensions of the irradiation room:
    3 x 6 m2

  • Irradiation conditions:
    No activation of the samples

  • Energy range:
    0.2 - 3.5 MeV

  • Current:
    ~1 pA - 1 mA


  • Dose rate in X at 1 m:
    0.1 µGy/h - 500 Gy/h

  • Beam scanning:
    uniform field +/- 15°
  • Fluency:
    up to 6x1015 e-/s

  • Scanned surface:
    up to 40 x 220 mm2

Beam emittance

Removable X target:

Possible irradiation in X or in e-
LAETICIA

Irradiation chamber allowing to simulate extreme environmental conditions:

  • Temperature tuning:
    • from 80 K to 600 K,
  • Atmosphere tuning:
    • Irradiation in vacuum,
    • Irradiation under N2, Ar, Air, etc.
  • Samples size until 150x150 mm2.
Development of detectors
Calibration with a reference source
Ageing tests
Semiconductor doping
Fault measurement
Qualification of components for aerospace
Cross-linking, polymer grafting
Thin film surface treatment
Fireproofing of cables and tubes
Professional training
Drafting of certification application files
Sterilisation of medical equipment
Research in radiobiology
Phytosanitary water treatment
Improvement of food preservation

Examples of applications in irradiation of materials


  • Coating tests
    • 400 keV ebeam scanned over a 40 × 150 mm2 surface for 1 h at 1 µA
    • Qualification for space applications

  • Qualification of metal alloys of industrial interest
    • 2 MeV ebeam scanned over a 16 × 20 mm2 surface for 17 days at 420 µA
    • Reproduction of 0.04 dpa - 30 samples maintained at 300 °C during irradiation

Examples of applications in equipment qualification


  • Luminaire qualification
    • X irradiation field at 100 Gy/h for 90 h with a dose target of 9 kGy
    • Selection of luminaires for nuclear environment (reactor building, red zone)

  • Characterization of radiation detectors
    • X irradiation field up to 3.5 MeV at 50 krad/h (500 Gy/h) for 20 h
    • Linearity Tests of RADFETs for Space Applications

Determination of X / 60-Co equivalences


ATRON is a contributing member of the RADNEXT program (H2020), WP7-JRA3 "cumulative radiation effects on electronics" (TID)

  • mechanisms at the origin of the damage
  • adapted test methodologies (electronic components and systems).

Submission of a request for modification of the RCC-E code (AFCEN) aimed at consolidating this equivalence:

  • Design and construction rules for electrical and I&C systems and equipment.

ATRON
Accelerator of your ambitions

www.atron.fr/en/presentation