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Title: Hybrid Enrichment Verification Array: Module Characterization Studies

The work presented in this report is focused on the characterization and refinement of the Hybrid Enrichment Verification Array (HEVA) approach, which combines the traditional 186-keV 235U signature with high-energy prompt gamma rays from neutron capture in the detector and surrounding collimator material, to determine the relative enrichment and 235U mass of the cylinder. The design of the HEVA modules (hardware and software) deployed in the current field trial builds on over seven years of study and evolution by PNNL, and consists of a ø3''×3'' NaI(Tl) scintillator coupled to an Osprey digital multi-channel analyzer tube base from Canberra. The core of the HEVA methodology, the high-energy prompt gamma-ray signature, serves as an indirect method for the measurement of total neutron emission from the cylinder. A method for measuring the intrinsic efficiency of this “non-traditional” neutron signature and the results from a benchmark experiment are presented. Also discussed are potential perturbing effects on the non-traditional signature, including short-lived activation of materials in the HEVA module. Modeling and empirical results are presented to demonstrate that such effects are expected to be negligible for the envisioned implementation scenario. In comparison to previous versions, the new design boosts the high-energy prompt gamma-ray signature, providesmore » more flexible and effective collimation, and improves count-rate management via commercially available pulse-processing electronics with a special modification prompted by PNNL.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
OSTI Identifier:
1328062
Report Number(s):
PNNL--25066
DN4001030; TRN: US1700046
DOE Contract Number:
AC05-76RL01830
Resource Type:
Technical Report
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION; URANIUM 235; PROMPT GAMMA RADIATION; NAI DETECTORS; NEUTRON REACTIONS; MULTI-CHANNEL ANALYZERS; ENRICHMENT; COMPARATIVE EVALUATIONS; KEV RANGE 100-1000; DESIGN; HYBRID SYSTEMS; VERIFICATION; COMPUTER CODES; COUNTING RATES; CAPTURE; COLLIMATORS; CYLINDERS; COMPUTERS; MANAGEMENT; MASS; MODIFICATIONS