M. Koestlbauer, V. Nizhnik SGTS/TND G. Sheppard SGCP/CTR Application of Lanthanum Bromide Detectors for the IAEA Safeguards Verification M. Koestlbauer, V. Nizhnik SGTS/TND G. Sheppard SGCP/CTR

Limitations of Ge and NaI detectors Germanium (Ge) detectors Slow time shaping: unsatisfactory performance in high background (count rate) applications, like recycled uranium enrichment measurement. High dead-time. Requires Liquid Nitrogen (LN) cooling: long cooling/preparation time before start of measurement Certain facilities do not allow LN use due to safety reasons LN dewar maks detector more bulky: limited portability Sodium Iodide (NaI) detectors Poor resolution: bad Peak-to-Compton background ratio Non-resolving/overlaping gamma peaks Poor linearity and temperature stability

LABR: Key Parameters Performance Lanthanum Bromide (LABR) – scintillation gamma detector Room temperature operation (no LN need, fast instrument preparation for the measurement, convenience in use, excellent portability) 2-3 times better energy resolution versus NaI: 5% vs 10-12% at 185keV High and fast light output (high count rate capability; low dead-time) Good linearity and temperature stability % DT Ge vs LaBr dead-time Spectra of SIL uranium standard taken with LABR and NAID Count Rate kcpsc U-235 peaks

Uranium Bottle Verification System (UBVS) RRP Recycled Uranium stored in containers of big bottle type: Avoid to use LN cooling: LN cooled Ge detector is not applicable Very high background from U-232 daughter products (high counting rate): high dead-time effects; Electrically Cooled Germanium System (ECGS) is not applicable 238keV peak from Pb-212 (daughter of U-232): peaks overlapping and influence on 185keV area determination in NAID spectra Accumulation of U-232 daughter products with time Recycled Uranium Spectrum for NAID 185keV 238keV Pb-212 RIO 1 RIO 2

LaBr vs NaID Verification Results for UBVS Required RSD 4.5% NAID performance Average OID -16.3% Avg. Uncertainty 4.8 % LABR performance Average OID -2.7% Avg. Uncertainty 2.6 % UBVS Measurement with LABR Average over the measurement campaign

Fuel Rods Verification Standard measurement setup: NaI detector with V-shape collimator: calibration constant is rod diameter dependent 2 ROI method for 185keV area determination: background variation sensitive No attenuation correction: cladding material type and thickness sensitive No burnable poison correction: sensitive to presence of Gd/Er/Dy burnable poison and its concentration Need for calibration for each combination of Rod Diameter, Cladding Type and Thickness, Burnable Poison Type and Concentration. Hundreds of calibration standards and corresponding measurements to establish calibrations for the whole range of combinations of fuel rods parameters

LaBRod: LaBr for Rods Method F Verification Monte-Carlo Modeling (Corrections) Fuel Pellet Diameter (D), mm 7.5 – 14.0 Cladding Thickness (Th), mm 0.0 – 3.0 Cladding Type (K): Zr, SS, Al LaBRod Software Development Automatic Reporting in PDF format Instrument-Collimator Setup Category A (Oct 2011)

Fuel Rods Verification Fuel Rods Enrichment Verification Results at a Fuel Fabrication Plant Average value of OID and Measurement Uncertainty for the verification campaign Average OID, rel. % -0.9% Average Unc., rel.% 1.00% RSD-ITV 2010, rel.% 3.2 %

Fuel Pellets Verification Standard measurement setup: NaI detector with Al spacer: poor Peak-to-Compton background ratio; long counting time Instrument Calibration– Monte-Carlo calculations at the HQ prior sending equipment to the field: no possibility to calibrate the instrument in the field, when operator introduces new pellets design No burnable poison correction: sensitive to presence of Gd/Er/Dy burnable poison and its concentration Need to recall instrument back to the HQ if a calibration for a new pellet design is needed Standard measurement time is 600-1800s

LaBPel: LaBr for Pellets Method F Verification Monte-Carlo Modeling (Corrections) LaBPel Analysis Software Development Ext. Diameter (D), mm 7.0 – 16.0 Pellet Height (H), mm 0.0 – 3.0 Internal hole (Din): 0-50% D Instrument-Collimator Setup UO2 Fuel Pellet Plastic Holder LaBr Crystal + Automatic Reporting in PDF format Collimator Assembly Category A (Oct 2011)

Fuel Pellets Verification Enrichment measurement of fuel pellets during the training course (CIE at Bulk Handling Facilities 2011) Average OID, rel.%: Detector 1 -0.1 % Detector 2 -5.0 % Average Unc., rel.%: Detector 1 2.6 % Detector 2 3.3 % Typical Sigma historical: 4-5% OID, % Average value of OID and Measurement Uncertainty for the verification campaign