Julian Atfield

Canadian Nuclear Laboratories | AECL

This paper summarizes the results of experimental measurements on mixed-oxide (²³³U,Th)O2 fuel bundles in the ZED-2 heavy water critical facility of Canadian Nuclear Laboratories (CNL) in Chalk River, Canada. Pressure-tube heavy water reactors can use such fuel to extract the energy potential of thorium, which helps extend nuclear energy resources...

The space dependent reactor core transfer functions differ from the point reactor transfer functions that have no spatial dependence. During experiments using different perturber and detector positions, it was found that the imaginary part of the ZED-2 reactor core transfer function approximates better the imaginary part of the point reactor transf...

In this work we apply the Geant4 toolkit and recent fission yield data to calculate the photoneutron yield from the thermal fission of 233,235U and 239Pu within a quasi-infinite bath of D2O. The simulation results were fit to a series of exponential terms enabling a direct comparison to historical “11 group” photoneutron data and the application fo...

The inherent safety of the SLOWPOKE-2 (Safe Low Power Kritical Experiment) reactor design relies on maintaining a low core excess reactivity limit of <400 pcm at all times. This restriction places high importance on reactivity shimming, accomplished by the periodic addition of beryllium plates to the top of the core. These additions are required ev...

Neutronic transient measurements of substitution cores composed of low enriched uranium oxide driver fuel and uranium-plutonium (as simulated mid-burnup natural uranium), plutonium-thorium, or uranium-233-thorium mixed oxide fuels in a heavy water moderated lattice are presented. The measurements recorded flux at several detector locations outside...

The sensitivity of criticality to nuclear data has been investigated using 39 (Pu,Th)O2 test fuel experiments that were completed in the ZED-2 reactor. Simulations were performed, for all experiments, using the multi-group Monte Carlo neutron transport code KENO V.a. The forward and adjoint fluxes were calculated to determine the sensitivity to all...

Dynamic parameters such as prompt neutron generation time are essential to safety analysis of a nuclear reactor. Currently, Monte Carlo based simulation methods are relied on for obtaining such dynamic parameters. There are known disagreements between different simulation codes. Further, the nuclear data that all simulations are based on cannot be...

This paper describes an experimental approach where reactor kinetics experiments are used to study reactor physics phenomena that are normally investigated using static-measurement techniques. This approach provides validation data relating to these phenomena for a range of core reactivities, rather than only providing data at critical conditions....

Monte Carlo simulations are applied to the full-reactor analysis of the SLOWPOKE design. The temperature reactivity feedback calculated by using the MCNP code for either the high enriched uranium (HEU) or low enriched uranium (LEU) core is in good agreement with the experimental data, with a k-eff bias of +3.3 mk for a HEU core and +6 mk for a LEU...

Presentation discusses results of comparing MCNP and WIMS-AECL/RFSP predictions of reactor physics characteristics (keff, flux distributions, transient power/flux vs. time, device worth, etc.) of ZED-2 experiments with ACR-type fuels. Results show good agreement with low or modest biases in keff, coolant void reactivity, device worth and relatively...

This paper summarizes comparisons between MCNP5 and WIMS-AECL / DRAGON / RFSP calculations and experimental results obtained from the Zero Energy Deuterium (ZED-2) critical facility at AECL Chalk River Laboratories. MCNP5 and WIMS-AECL / DRAGON / RFSP were used to calculate reactivity worths for two reactivity devices, a mechanical zone controller...

Experiments were performed in the ZED-2 (Zero Energy Deuterium) critical facility at AECL Chalk River Laboratories using a 24-cm pitch square lattice of 52 channels of heavy-water-moderated ACR-LEU and CANFLEX-LEU 43-element low-enriched uranium fuel bundles. These fuel bundles were cooled with H 2O, air (void) or a checkerboard pattern of H2O and...

We measure the number of companions per galaxy (Nc) as a function of r-band absolute magnitude for both the Sloan Digital Sky Survey and the Croton et al. (2006) semi-analytic catalog applied to the Millennium Run simulation. For close pairs with projected separations of 5-20 h^{-1} kpc, velocity differences less than 500 km/s, and luminosity ratio...

We show that a highly reliable and compact wavemeter incorporating a reference laser and traveling Michelson interferometer can be controlled, and the unknown wavelength determined, using readily programmable microcontroller circuits. These chips, powered by a 5 V supply, each replace a network of many electronic components and enable equipment to...