Neutron Flux Measurements in the Side-Core Region of Hunterston B Advanced Gas-Cooled Reactor

Allen, D. A.; Shaw, S. E.; Huggon, A. P.; Steadman, R.; Thornton, D. A.; Whiley, G. S.

doi:10.1520/stp49642t

Cited by 2 publications

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Reanalysis of graphite nuclear data limits for AGR dosimetry with updated carbon scattering data and Magnox plant measurements

Shaw,

Allen

2024

EPJ Web Conf.

View full text Add to dashboard Cite

The Advanced Gas-cooled Reactors (AGR) operating in the UK are, like the Magnox reactors that preceded them, graphite moderated and cooled by pressurised CO2 gas. As such, the nuclear data for carbon are of primary importance in neutron dosimetry and nuclear heating calculations. There is evidence from benchmark data and plant measurements of underprediction of neutron fluxes at the lower end of the fast neutron range for thicknesses of graphite greater than ~50 cm. Furthermore, the range of validation is limited to ~70 cm of graphite, with components beyond this being allocated bounding damage rates. Following the previous ISRD, opportunities were taken to: Look again at the carbon scattering cross-sections by incorporating the ENDF/B-VIII.0 Beta 4 carbon data to assess the impact on the analysis of benchmark data. Reassess validation data from the earlier Magnox reactors to put them on a more appropriate equivalent graphite thickness scale to the AGRs. The investigation into graphite nuclear data libraries concluded that the incorporation of ENDF/B-VIII Beta 4 carbon data into the JEF2.2 and ENDF/B-VII.1 data libraries with BINGO collision processing had only a limited effect on the calculated responses. The UKNDL data, with DICE collision processing, currently used in dosimetry calculations for EDF Energy’s AGRs produces the closest agreement with measurement for all calculated responses for graphite thicknesses greater than 10 cm. For reactor plant validation, applying the sensitivity of the 93mNb(n,n’) response to graphite density resulted in a 15 cm increase to the validation database when compared to a simple “straight-line” distance. However, caution is advised in applying the benchmark equivalent distance derived from locations within a graphite column, to ex-core plant measurements.

show abstract

Reanalysis of graphite nuclear data limits for AGR dosimetry with updated carbon scattering data and Magnox plant measurements

Shaw,

Allen

2024

EPJ Web Conf.

View full text Add to dashboard Cite

show abstract

Validation of MCBEND Dosimetry Predictions against Measurements from Hunterston B Advanced Gas-Cooled Reactor

Allen

Thornton

Shaw

et al. 2018

Reactor Dosimetry: 16th International Symposium

View full text Add to dashboard Cite

The core restraints of advanced gas-cooled reactors are important structural components necessary for maintaining the geometric integrity of the cores. Neutron damage and nuclear heating rates, calculated using the Monte Carlo code MCBEND, have underpinned the safety case for continued operation of four reactors. To validate these calculations, neutron activation measurements were commissioned. A neutron flux activation “stringer” was deployed in the graphite side reflector of one of the Hunterston B reactors and irradiated for a period of approximately three years. A capsule attached to the bottom end of this cable contained a range of fast and thermal neutron activation monitor wires to provide additional spectral information. Following its successful withdrawal, measurements were undertaken at SCK-CEN’s laboratory in Mol, Belgium, to provide monitor wire activities. In parallel with this, activation calculations were undertaken by Amec Foster Wheeler using a MCBEND model tailored to the state of the reactor during the irradiation period. Time-varying neutron source data were used, decay-adjusted for the half-lives of the activation monitors, in order to accommodate the effects upon the expected activities of time-varying reactor power. Adjustments were made for neutron flux attenuation within the stringer capsule and cable and, where necessary, corrections were also made for parent and activation nuclide burnout. There was no requirement for spectral adjustment. Excellent agreement between calculated and measured activities was obtained for both fast and thermal neutron responses; the overall calculated/measured ratios were 1.14 ± 0.15 and 1.11 ± 0.12, respectively. These are sufficiently close to the desired value of unity to provide confidence in the ability of the calculation route to predict neutron damage rates within the core restraint components. This successful validation supports the case for life extension of the Hunterston B and Hinkley Point B power plants.

show abstract

Neutron Flux Measurements in the Side-Core Region of Hunterston B Advanced Gas-Cooled Reactor

Cited by 2 publications

References 0 publications

Reanalysis of graphite nuclear data limits for AGR dosimetry with updated carbon scattering data and Magnox plant measurements

Reanalysis of graphite nuclear data limits for AGR dosimetry with updated carbon scattering data and Magnox plant measurements

Validation of MCBEND Dosimetry Predictions against Measurements from Hunterston B Advanced Gas-Cooled Reactor

Contact Info

Product

Resources

About