Tensioned Metastable Fluid Detectors in Nuclear Security for Active Interrogation of Special Nuclear Materials―Part B

Jeffrey A Webster,Rusi P Taleyarkhan

doi:10.4236/wjnst.2011.13011

Abstract

This paper (constituting Part B) addresses active interrogation for detecting Special Nuclear Materials (SN- Ms) and includes description of the transformational Tensioned Metastable Fluid Detector (TMFD) based method for optimal monitoring. One of the greatest difficulties in detection of SNMs by active interrogation is the task of distinguishing between the probing particles and the secondary particles that indicate the presence of SNMs. The TMFD’s selective insensitivity and γ photon blindness features are advantageous for alleviating this problem. The working principle of the TMFD is discussed along with its applications for security. The experimental work to date involving detection of small quantities of uranium with conventional detectors is discussed along with results of fission neutron detection. Statistically significant detection was achieved within 5 minutes of counting to ascertain and measure conclusive evidence for the presence of a 55g sample of uranium containing 235U. Results of simulations of three active detection techniques utilizing a TMFD system are presented. The process for using the TMFD to discriminate active source particles using timing and energy are described. These simulations indicate that it should be possible to utilize the TMFD system for optimal neutron-based interrogation of SNMs.

Highlights

This paper describes the process and potential benefits of detection of special nuclear materials (SNMs) by use of active neutron-based interrogation, including use of conventional and novel Tensioned Metastable Fluid Detector (TMFD) technology [1]
The level at which the lower level discriminator had been set for neutron counting was the setting for the upper level discriminator, which resulted in the opposite effect
Designed experimental work with conventional detectors has allowed us the ability to detect uranium in significantly smaller quantities than that reported in the literature by others

Summary

Introduction

This paper describes the process and potential benefits of detection of special nuclear materials (SNMs) by use of active neutron-based interrogation, including use of conventional and novel TMFD technology [1]. Passive detector systems can become incapable for nuclear security-related monitoring if the SNM is cleverly hidden by a determined adversary. This comprises a nuclear security issue at large that, may be possible to overcome with an optimally derived solution-one which combines use of an interrogating source (such as neutrons or photons) to induce nuclear reactions in deeply buried (or cloaked) SNMs and thereby, deriving a strong enough characteristic signal which can be monitored with a detector that is optimal for that situation. The principle of SNM detection via active interrogation is discussed first, followed with description of experiments configured and successfully conducted for detecting minute quantities of fissile uranium, followed thereafter, with description of the TMFD technology accompanied with adaptation for active interrogation

Methods

Results

Conclusion