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Csaba ROTH

INSTITUTUL DE CERCET Ă RI NUCLEARE PITE Ş TI. Calibration and references in neutron field measurements. Csaba ROTH. Calibration and references in neutron field measurements.

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Csaba ROTH

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  1. INSTITUTUL DE CERCETĂRI NUCLEARE PITEŞTI Calibration and references in neutron field measurements Csaba ROTH Conferinţa “Progrese în Criogenie şi Separarea Izotopilor”, Călimăneşti-Căciulata

  2. Calibration and references in neutron field measurements • The large utilization of the neutrons, starting from simple devices working with neutron sources up to the nuclear reactors, involves a large diversity of tools used for specific measurements. • Any apparatus used for measurements affecting the public interest is subject of the state metrological control • Neutron measurements - no apparatus or tools mentioned in the Official List and no standards available in our national standards system. • Calibration and measurement certificates issued by foreign organizations are valid. Conferinţa “Progrese în Criogenie şi Separarea Izotopilor”, Călimăneşti-Căciulata

  3. Calibration and references in neutron field measurements • Standards and references in neutron measurements: • Neutron fields with well known characteristics • Reference apparatus • Reference sources (fast neutrons) Status in Romania: “reference field” type facility developed at the VVR-S Reactor operated by the National Institute for Physics and Nuclear Engineering, authorized as National Standard of the Thermal Neutron Flux Density Unit – no more in available Conferinţa “Progrese în Criogenie şi Separarea Izotopilor”, Călimăneşti-Căciulata

  4. Calibration and references in neutron field measurements The reference thermal neutron irradiation facility developed at the Institute for Nuclear Research from Pitesti is a dry cavity placed into the graphite thermal column of the TRIGA-SSR core. Conferinţa “Progrese în Criogenie şi Separarea Izotopilor”, Călimăneşti-Căciulata

  5. Calibration and references in neutron field measurements • Characteristics of the irradiation facility : • Temperature: (40 ± 4) oC • Cadmium ratio for 197Au(n,) reaction: 52.1 ± 3% • Neutron flux density (fluence rate), as function of monitors count rate: • Φ/MON1 = (6.48±0.32)x108 neutrons/m2•s•cps • Φ/MON2 = (9.14±0.46)x1010 neutrons/m2•s•cps • Thermal neutron weight (E<0.135 eV) = (95.2±1)% • Gamma dose rate reported to monitor 2 count rate: 0.27 Gy/hour/cps • Neutron flux densities values from 2•1010 neutrons/m2•s up to 5•1014 neutrons/m2•s. Conferinţa “Progrese în Criogenie şi Separarea Izotopilor”, Călimăneşti-Căciulata

  6. Calibration and references in neutron field measurements • Computation & measurements: • MCNP computation • Multifoil activation method • Fission rates measurements • Spectrum unfolding • Similar results obtained using the Wescott classical method Conferinţa “Progrese în Criogenie şi Separarea Izotopilor”, Călimăneşti-Căciulata

  7. Calibration and references in neutron field measurements Flux density space distribution Conferinţa “Progrese în Criogenie şi Separarea Izotopilor”, Călimăneşti-Căciulata

  8. Calibration and references in neutron field measurements • National standard qualification related problems • The irradiation facility has well known and reproducible neutron characteristics. • According to the national standard certification procedures requirements, resulting from the MRA requirements, the main problems are: • the traceability • the capability of transferring the measurement units to lower rang standards or tools. Conferinţa “Progrese în Criogenie şi Separarea Izotopilor”, Călimăneşti-Căciulata

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