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Title: 5 years of research of Differential Die-Away (DDA) Instrument within the Next Generation Safeguards Initiative

Abstract

No abstract provided.

Authors:
ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1410613
Report Number(s):
LA-UR-17-30708
DOE Contract Number:
AC52-06NA25396
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION; Differential Die-Away; effective fissile content; active interrogation; plutonium content

Citation Formats

Henzl, Vladimir. 5 years of research of Differential Die-Away (DDA) Instrument within the Next Generation Safeguards Initiative. United States: N. p., 2017. Web. doi:10.2172/1410613.
Henzl, Vladimir. 5 years of research of Differential Die-Away (DDA) Instrument within the Next Generation Safeguards Initiative. United States. doi:10.2172/1410613.
Henzl, Vladimir. Wed . "5 years of research of Differential Die-Away (DDA) Instrument within the Next Generation Safeguards Initiative". United States. doi:10.2172/1410613. https://www.osti.gov/servlets/purl/1410613.
@article{osti_1410613,
title = {5 years of research of Differential Die-Away (DDA) Instrument within the Next Generation Safeguards Initiative},
author = {Henzl, Vladimir},
abstractNote = {No abstract provided.},
doi = {10.2172/1410613},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Nov 22 00:00:00 EST 2017},
month = {Wed Nov 22 00:00:00 EST 2017}
}

Technical Report:

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  • New Monte Carlo simulations of the differential die-away (DDA) instrument response to the assay of spent and fresh fuel helped to redefine the signal-to-Background ratio and the effects of source neutron tailoring on the system performance. Previously, burst neutrons from the neutron generator together with all neutrons from a fission chain started by a fast fission of 238U were considered to contribute to active background counts. However, through additional simulations, the magnitude of the 238U first fission contribution was found to not affect the DDA performance in reconstructing 239Pu eff. As a result, the newly adopted DDA active background definitionmore » considers now any neutrons within a branch of the fission chain that does not include at least one fission event induced by a thermal neutron, before being detected, to be the active background. The active background, consisting thus of neutrons from a fission chain or its individual branches composed entirely of sequence of fast fissions on any fissile or fissionable nuclei, is not expected to change significantly with different fuel assemblies. Additionally, while source tailoring materials surrounding the neutron generator were found to influence and possibly improve the instrument performance, the effect was not substantial.« less
  • Four helium-3 ( 3He) detector/preamplifier packages (¾”/KM200, DDSI/PDT-A111, DDA/PDT-A111, and DDA/PDT10A) were experimentally tested to determine the deadtime effects at different DT neutron generator output settings. At very high count rates, the ¾”/KM200 package performed best. At high count rates, the ¾”/KM200 and the DDSI/PDT-A111 packages performed very well, with the DDSI/PDT-A111 operating with slightly higher efficiency. All of the packages performed similarly at mid to low count rates. Proposed improvements include using a fast recovery LANL-made dual channel preamplifier, testing smaller diameter 3He tubes, and further investigating quench gases.
  • Fresh fuel experiments for the differential die-away (DDA) project were performed using a DT neutron generator, a 15x15 PWR fuel assembly, and nine 3He detectors in a water tank inside of a shielded cell at Los Alamos National Laboratory (LANL). Eight different fuel enrichments were created using low enriched (LEU) and depleted uranium (DU) dioxide fuel rods. A list-mode data acquisition system recorded the time-dependent signal and analysis of the DDA signal die-away time was performed. The die-away time depended on the amount of fissile material in the fuel assembly and the position of the detector. These experiments were performedmore » in support of the spent nuclear fuel Next Generation Safeguards Initiative DDA project. Lessons learned from the fresh fuel DDA instrument experiments and simulations will provide useful information to the spent fuel project.« less