A Decade of Dosimetry for Magnox Reactor Plants

Lewis, T.A.; Thornton, D. A.

doi:10.1142/9789812705563_0034

Cited by 9 publications

(4 citation statements)

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“…From the results of fast neutron reactions 32 S(n,p) 115 In(n,n') and 103 Rh(n,p), the Winfrith graphite benchmark comparison [4] indicated that MCBEND would systematically and progressively under-predict fast dpa at graphite penetrations exceeding 50 cm; this was confirmed with measurements of 93 Nb(n,n') on the plant (see Fig. 2 of [1]). Modelling of the benchmarks with MCNP and a range of nuclear data libraries showed this to be a generic effect and attributed to deficiencies in the nuclear data for carbon (e.g.…”

Section: Uncertainties Derived From Benchmarks and Later Measurementsmentioning

confidence: 69%

“…The issue was addressed by the application of an empirically derived correction; the Nuclear Data Correction Factor 02009-p. 3 (NDCF) varies linearly from 1.0 at 50 cm thickness (i.e. no observed effect) to 1.43 at a maximum thickness of 71.6 cm beyond which there are no data [1].…”

Section: Uncertainties Derived From Benchmarks and Later Measurementsmentioning

confidence: 97%

“…In the late 1980's a ten year programme of measurements, methods developments and dosimetry assessments was begun to support continued operation of the Magnox plant [1]. Some issues affecting Magnox were shown to be relevant and prompted developments to the AGR dosimetry programme.…”

Section: Impact Of the Magnox Experience On Agr Dosimetrymentioning

confidence: 99%

“…Modelling of the benchmarks with MCNP and a range of nuclear data libraries showed this to be a generic effect and attributed to deficiencies in the nuclear data for carbon (e.g. see [1]). The issue was addressed by the application of an empirically derived correction; the Nuclear Data Correction Factor 02009-p. 3 (NDCF) varies linearly from 1.0 at 50 cm thickness (i.e.…”

Section: Uncertainties Derived From Benchmarks and Later Measurementsmentioning

confidence: 99%

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A History of Dosimetry for the Advanced Gas-cooled Reactors

Shaw

Thornton²

2016

EPJ Web of Conferences

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Abstract. This paper presents a summary of the methods used in the first ∼40 years of AGR neutron dosimetry and nuclear heating calculations, and the influence of the earlier Magnox reactor dosimetry programme. While the current state-of-the-art Monte Carlo methods are extremely powerful they still require very careful consideration of the quality of the input data, nuclear data validation and variance reduction techniques; in particular, this paper examines the difficulties in assuring the adequate convergence of calculations when Monte Carlo acceleration is applied in the presence of significant streaming paths through attenuating or scattering media.

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Section: Uncertainties Derived From Benchmarks and Later Measurementsmentioning

confidence: 69%

Section: Uncertainties Derived From Benchmarks and Later Measurementsmentioning

confidence: 97%

Section: Impact Of the Magnox Experience On Agr Dosimetrymentioning

confidence: 99%

Section: Uncertainties Derived From Benchmarks and Later Measurementsmentioning

confidence: 99%

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A History of Dosimetry for the Advanced Gas-cooled Reactors

Shaw

Thornton²

2016

EPJ Web of Conferences

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

Shaw,

Allen

2024

EPJ Web Conf.

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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.

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