Axial offset anomaly: coupling PWR primary chemistry with core design

Frattini, P. L.; Blök, J.; Chauffriat, S.; Sawicki, J.; Riddle, John M.

doi:10.1680/nuen.40.2.123.39952

Cited by 17 publications

(22 citation statements)

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“…Large amounts of boron, deposited on fuel in an axially asymmetric fashion, can give rise to the depression of thermal neutron flux in the upper part of a reactor. Such anomalous flux depressions, termed axial offset anomalies (AOAs), have been observed in increasing numbers of high-duty PWRs that use high burn-up fuel operated at high temperatures and long fuel cycles [1,2]. The affected plants typically undergo local sub-cooled nucleate boiling in the highest-power channels, which leads to an enhanced susceptibility to AOA.…”

Section: Introductionmentioning

confidence: 99%

Evidence of Ni2FeBO5 and m-ZrO2 precipitates in fuel rod deposits in AOA-affected high boiling duty PWR core

Sawicki

2008

Journal of Nuclear Materials

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Section: Introductionmentioning

confidence: 99%

Evidence of Ni2FeBO5 and m-ZrO2 precipitates in fuel rod deposits in AOA-affected high boiling duty PWR core

Sawicki

2008

Journal of Nuclear Materials

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“…Previous modelling results by other groups had indicated that LiBO 2 (s) would not precipitate out until crud thicknesses reached well above a hundred microns [20]. The reason this model predicts precipitation at much smaller crud thicknesses can be understood from Fig.…”

Section: Discussion Of Ccm Resultsmentioning

confidence: 68%

“…4 indicates the rise in species concentrations towards the bottom of the crud causes a rise in the saturation temperature and because the solubility of LiBO 2 (s) falls with increasing temperature it precipitates. This rise in temperature was not accounted for in previous models [20].…”

Section: Discussion Of Ccm Resultsmentioning

confidence: 88%

A model of chemistry and thermal hydraulics in PWR fuel crud deposits

Henshaw¹,

McGurk²,

Sims³

et al. 2006

Journal of Nuclear Materials

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“…27,28) This can be compounded with core flow maldistribution due to significant increases in flow resistance caused by surface fouling. 25,29) While the AOA phenomenon does not represent a direct safety concern, it can entail reactor power constrains and derating to maintain the required shutdown margin, with the consequence of economic penalty.…”

Section: Introductionmentioning

confidence: 99%

A Separate-Effect-Based New Appraisal of Convective Boiling and its Suppression

Aounallah

2008

J. Nucl. Sci. Technol.

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The development of convective boiling heat transfer correlations and analytical models has been based almost exclusively on the knowledge of global heat transfer coefficients, while the predictive capabilities of the correlation constituting components (typically additive convection and boiling) have remained usually elusive. This becomes important when, for example, developing a mechanistic subcooled void model based on wall heat flux partitioning, or when applying a correlation beyond its developmental range. In the latter case, the preponderance of the individual heat transfer mechanisms, through the phenomenon of boiling suppression, can become significantly different, thus leading to uncharted uncertainty extrapolations. An examination of existing experimental data, obtained under fixed hydrodynamic conditions, has allowed the isolation of the boiling heat transfer contribution over a broad range of thermodynamic qualities (0 to 0.8) and mass fluxes (1,100 to 3,900 kg/(m 2 Ás)) for water at 7.2 MPa. Boiling suppression has been quantified, thus providing valuable new insights on the basic functional relationships of boiling in convective flows. This work has allowed a new interpretation and representation of the standard flow ''boiling map'' (Collier's) to be developed. The convection enhancement and boiling suppression components (F and S) of the well-known Chen's correlation-an important constitutive relationship implemented in several best-estimate (realistic) thermal-hydraulics codes-have been individually determined, showing the pitfall of splitting the correlation for mechanistic boiling heat transfer modelling, and the important role of compensating errors in uncertainty extrapolation. An initial attempt to formulate a new correlation, based for the first time on segregated heat transfer components, is also included.

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Axial offset anomaly: coupling PWR primary chemistry with core design

Cited by 17 publications

References 0 publications

Evidence of Ni2FeBO5 and m-ZrO2 precipitates in fuel rod deposits in AOA-affected high boiling duty PWR core

Evidence of Ni2FeBO5 and m-ZrO2 precipitates in fuel rod deposits in AOA-affected high boiling duty PWR core

A model of chemistry and thermal hydraulics in PWR fuel crud deposits

A Separate-Effect-Based New Appraisal of Convective Boiling and its Suppression

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