Fast-neutron multiplicity counter for active measurements of uranium oxide certified material

Fulvio, Angela Di; Shin, Tony H.; Basley, A.; Sosa, Charles; Clarke, Shaun D.; Sanders, J.E.; Watson, Scott M.; Chichester, D.L.; Pozzi, SA

doi:10.1016/j.nima.2018.05.049

Cited by 20 publications

(3 citation statements)

References 35 publications

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“…where σ k , σ b , and Cov(k, b) are the standard deviation of fit parameter k, b and their covariance obtained in the data fitting, σ y is the uncertainty associated with the measured count rate shown in Eq. ( 1) [20]. We calculated the relative uncertainty associated with x for pebbles with enrichment ranging from 5% to 15%, as shown in Fig.…”

Section: Simulation Of Active Interrogation Of Triso Fuel Pebblesmentioning

confidence: 99%

Boron Coated Straw-based Neutron Multiplicity Counter for Neutron Interrogation of TRISO Fueled Pebbles

Fang¹,

Lacy²,

Athanasiades³

et al. 2023

Preprint

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Pebble bed reactors (PBRs) can improve the safety and economics of the nuclear energy production. PBRs rely on TRIstructural-ISOtropic (TRISO) fuel pebbles for enhanced fission product retention. Accurate characterization of individual fuel pebbles would enable the validation of computational models, efficient use of TRISO fuel, and improve fuel accountability. We have developed and tested a new neutron multiplicity counter (NMC) based on 192 boron coated straw (BCS) detectors optimized for 235 U assay in TRISO fuel. The new design yielded a singles and doubles neutron detection efficiency of 4.71% and 0.174%, respectively, and a die-away time of 16.7 µs. The NMC has a low intrinsic gamma-ray detection efficiency of 8.71 × 10 −8 at an exposure rate of 80.3 mR/h. In simulation, a high-efficiency version of the NMC encompassing 396 straws was able to estimate the 235 U in a pebble with a relative uncertainty and error both below 2% in 100 s.

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Section: Simulation Of Active Interrogation Of Triso Fuel Pebblesmentioning

confidence: 99%

Boron Coated Straw-based Neutron Multiplicity Counter for Neutron Interrogation of TRISO Fueled Pebbles

Fang¹,

Lacy²,

Athanasiades³

et al. 2023

Preprint

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show abstract

“…Neutron measurements are used either for total counting (ie, pure metal fissile samples) or coincidences/multiplicity counting (ie, impure samples whose [α, n] to spontaneous fission (SF) ratio is well known or impure fissile samples in general). [13][14][15] Although concepts related to neutron multiplicity have been studied widely and are very well understood, there is still an overall lack of information on possible strategies that incorporate the subject matter for a fissile mass estimation regarding research reactors. 10 To properly quantify the mass of plutonium or uranium, operator input on the facility operational history is needed.…”

Section: Introductionmentioning

confidence: 99%

“…12 A variety of research study has investigated the use of flavours of neutron multiplicity measurement and simulation for fissile mass estimation. [13][14][15] Although concepts related to neutron multiplicity have been studied widely and are very well understood, there is still an overall lack of information on possible strategies that incorporate the subject matter for a fissile mass estimation regarding research reactors. Fission fragment production in a nuclear reactor is a function of the time-dependent BU as well as the power level.…”

Section: Introductionmentioning

confidence: 99%

Computation of the neutron multiplicity moments for research reactor fuels using MCNP6 and SOURCES4c

Dim

Aghara

2019

Int J Energy Res

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Summary Fissile material detection and quantification are often necessary for safeguards, nuclear security, and fuel management. Nondestructive assay, neutron, and gamma measurements are reliable means, which can facilitate the detection and estimation of the mass of fissile materials in a broad range of material matrix. Various flavours of neutron measurement are routinely used by facilities (like nuclear reactors, enrichment, and fabrication plants) to quantify fissile material mass and inventory lists. The Monte Carlo code, MCNP6, is used to model several neutron multiplicity measurements. A simulation scenario is set up in MCNP6 using the JCC71 neutron slab counter to obtain the multiplicity moments for fresh and irradiated fuel assemblies from the UMass Lowell Research Reactor (UMLRR) and Worcester Polytechnic Research Reactor (WPIRR). An MCNP6 burnup is initially performed on the fuel types under study to generate used fuel isotopic. The fresh and or used fuel isotopic is then used to produce independent SOURCES4c input tape1 files. SOURCES4c is used to generate (α, n), spontaneous fission spectrum, and the associated neutron emission rates necessary for the various fixed fuel source definitions in MCNP6 calculations. Under the comprehensive safeguards agreements, the International Atomic Energy Agency has the right and obligation to verify that no nuclear material is diverted from peaceful use to nuclear weapons or other nuclear explosive devices. Research reactors are required to be safeguarded facilities under the comprehensive safeguards. Several research efforts have studied the various flavours of neutron measurement for commercial power reactor operating at high power and long burnups; however, not nearly as many studies have been performed with neutron measurements for research reactors operating at relatively lower power and have significantly lower burnup. This work looks to establish the relevant isotopes to overall neutron source rate as well as the process involved in performing a typical neutron multiplicity measurement simulation for a research reactor fuel. The results demonstrate that the single and double moments for Worcester Polytechnic Institute (WPI) and UMLRR fuels can be measured reliably using two JCC71 slab detectors. The moment for the UMLRR and WPIRR fuel (in both fresh and used states) was estimated with a relative error below 0.031 for singles and 0.081 for doubles. The two fresh fuel types cannot be differentiated from each other on the sole basis of neutron analysis. However, fresh and irradiated fuel can be distinguished based on neutron multiplicity measurements.

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The effect of scintillator materials on the fast neutron multiplicity measurement

Zhang

et al. 2022

J Radioanal Nucl Chem

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Fast-neutron multiplicity counter for active measurements of uranium oxide certified material

Cited by 20 publications

References 35 publications

Boron Coated Straw-based Neutron Multiplicity Counter for Neutron Interrogation of TRISO Fueled Pebbles

Boron Coated Straw-based Neutron Multiplicity Counter for Neutron Interrogation of TRISO Fueled Pebbles

Computation of the neutron multiplicity moments for research reactor fuels using MCNP6 and SOURCES4c

The effect of scintillator materials on the fast neutron multiplicity measurement

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