The development of a new, neutron, time correlated, interrogation method for measurement of 235U content in LWR fuel assemblies

Menlove, H.O.; Menlove, S.H.; Rael, Carlos D.

doi:10.1016/j.nima.2012.10.081

Cited by 17 publications

(28 citation statements)

References 1 publication

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“…Recent work by Menlove [11] and Miller [12] has suggested that 252 Cf is a suitable alternative to 241 AmLi in many cases, and in fact provides several benefits over the traditional option. Americium lithium is an (α,n) source, which emits single neutrons randomly in time.…”

Section: Active Source Replacementmentioning

confidence: 99%

“…The 252 Cf contributes a significant coincidence background to fresh fuel measurements, which originally seemed to be a disadvantage. However, a new technique known as "timecorrelated induced fission (TCIF)" has been proposed by Menlove [11] to take advantage of the higher multiplicity of the californium source and thereby turn this disadvantage into an advantage.…”

Section: Active Source Replacementmentioning

confidence: 99%

“…However, a study by Menlove [11] provided the first evidence that 252 Cf sources might actually provide an improvement in counting statistics over 241 AmLi for the UNCL application. This result was affirmed again in later studies [12,25].…”

Section: Cf Sourcesmentioning

confidence: 99%

“…The TCIF method was developed as a way to substitute a spontaneous fission source, such as 252 Cf, in place of the traditional 241 AmLi source in an active detector [11]. A spontaneous fission source emits multiple correlated neutrons, which can either result in induced fission events within the sample or be directly captured within the detector.…”

Section: Tcifmentioning

confidence: 99%

“…Thus, the neutron leakage from the sample (and correspondingly the detected signal) is composed of both spontaneous fission neutrons from the source and induced fission neutrons from the sample, all of which are detected within the same gate. The required time gate is twice as long In theory, under ideal conditions, this higher-effective ̅ would simply be 5.12, which is the sum of the individual ̅ values of 252 Cf ( ̅ = 3.757) and 235 U ( ̅ = 2.44), with one neutron subtracted for induced fission within the 235 U [11]. However, because an assembly is a bulk material and many competing interactions are taking place within the fuel, the value of ̅ is lower than this ideal value.…”

Section: Tcifmentioning

confidence: 99%

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Technical Basis for the Use of a Correlated Neutron Source in the Uranium Neutron Coincidence Collar

et al. 2017

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Nuclear nonproliferation efforts rely on a variety of safeguards to protect sensitive materials in nuclear facilities. The enrichment of fresh light-water-reactor fuel assemblies is verified by several inspectorates using the uranium neutron coincidence collar (UNCL), which uses neutrons from an americium lithium ( 241 AmLi) source to interrogate the assemblies from one side. Eighteen 3 He tubes on the other three sides are used to count the coincidence neutrons from the induced fission reactions. Experiments have shown that 252 Cf could also be used to complete these measurements, providing several benefits over the use of the standard 241 AmLi source. The UNCL is one of the many instruments that will be available for training purposes in the China Center of Excellence for Nuclear Security (COE), which is located in Beijing, China. This thesis contains a detailed characterization of the response of this detector with 252 Cf as compared with 241 AmLi and an analysis of the technical basis for the use of 252 Cf in place of 241 AmLi in the Antech N2071 Neutron Coincidence Collar. This thesis (1) discusses the development a benchmarked, high-fidelity model of the UNCL using Monte Carlo N-Particle Extended (MCNPX), version 2.7.4.a; (2) fully characterizes the detection parameters, including the efficiency profile, die-away time, and deadtime parameters; and (3) demonstrates the technical basis for the replacement of 241 AmLi sources with 252 Cf sources by assessing the penetrability of neutrons from each source, evaluating the statistical uncertainty in the measurements incurred by each source, and investigating the possibility of a higher effective average number of neutrons produced per fission using 252 Cf rather than 241 AmLi. This work demonstrates the suitability of 252 Cf as a substitute for 241 AmLi and in fact shows approximately a 7.5% improvement in counting statistics over the traditional interrogation source at 4% enrichment.

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Section: Active Source Replacementmentioning

confidence: 99%

Section: Active Source Replacementmentioning

confidence: 99%

Section: Cf Sourcesmentioning

confidence: 99%

Section: Tcifmentioning

confidence: 99%

Section: Tcifmentioning

confidence: 99%

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Technical Basis for the Use of a Correlated Neutron Source in the Uranium Neutron Coincidence Collar

et al. 2017

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Principles of Neutron Coincidence Counting

Swinhoe,

Ensslin,

Hutchinson

et al. 2024

Nondestructive Assay of Nuclear Materials for Safeguards and Security

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This chapter describes the principles involved with using neutron coincidences that obtain more information about a measured sample than through singles counting alone. The chapter describes the origin of neutron correlations and how they manifest themselves in the neutron pulse train from a detector. The Rossi-α distribution is presented. The chapter then describes measurement and analysis methods used to extract and analyze correlated counting rates, such as the Feynman variance to mean method and the shift register coincidence circuit. These methods can be used to estimate fission rate and neutron multiplication. Dead time corrections, multiple pulsing and the uncertainties resulting from counting statistics are presented. Several passive methods for the determination of 240Pueffective mass are presented in detail: ‘passive calibration curve’, ‘known alpha’ and ‘known multiplication’. This is followed by a description of active coincidence methods, in which an external neutron source is used to induce fission in the item of interest. This section includes a discussion of the selection of the external source, the use of fast and thermal interrogation modes and a presentation of measurement uncertainties. One example is given of an active technique to measure uranium linear density and burnable poison simultaneously.

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Active Neutron Instrumentation and Applications

Swinhoe,

Ensslin,

Evans

et al. 2024

Nondestructive Assay of Nuclear Materials for Safeguards and Security

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This chapter describes the use of active neutron instrumentation, in which an external neutron source is used to induce fission in the item of interest. The chapter includes a description of the properties of a variety of neutron sources that can be used to induce fission in the item. The application presented include single neutron counting (Cf shuffler and the differential dieaway technique) and active coincidence counting (active well coincidence counter and various neutron collars for fresh uranium fuel). The chapter concludes with a description of active neutron multiplicity counting, including the active epithermal neutron multiplicity counter.

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The development of a new, neutron, time correlated, interrogation method for measurement of 235U content in LWR fuel assemblies

Cited by 17 publications

References 1 publication

Technical Basis for the Use of a Correlated Neutron Source in the Uranium Neutron Coincidence Collar

Technical Basis for the Use of a Correlated Neutron Source in the Uranium Neutron Coincidence Collar

Principles of Neutron Coincidence Counting

Active Neutron Instrumentation and Applications

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