DATA ASSIMILATION APPLIED TO PRESSURISED WATER REACTORS
Best estimate plus uncertainty is the leading methodology to validate existing safety margins. It remains a challenge to develop and license these approaches, in part due to the high dimensionality of system codes. Uncertainty quantification is an active area of research to develop appropriate metho...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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EDP Sciences
2021-01-01
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| Series: | EPJ Web of Conferences |
| Subjects: | |
| Online Access: | https://www.epj-conferences.org/articles/epjconf/pdf/2021/01/epjconf_physor2020_09020.pdf |
| _version_ | 1818614099339116544 |
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| author | Dixon J.R Lindley B.A. Taylor T. Parks G.T. |
| author_facet | Dixon J.R Lindley B.A. Taylor T. Parks G.T. |
| author_sort | Dixon J.R |
| collection | DOAJ |
| description | Best estimate plus uncertainty is the leading methodology to validate existing safety margins. It remains a challenge to develop and license these approaches, in part due to the high dimensionality of system codes. Uncertainty quantification is an active area of research to develop appropriate methods for propagating uncertainties, offering greater scientific reason, dimensionality reduction and minimising reliance on expert judgement. Inverse uncertainty quantification is required to infer a best estimate back on the input parameters and reduce the uncertainties, but it is challenging to capture the full covariance and sensitivity matrices. Bayesian inverse strategies remain attractive due to their predictive modelling and reduced uncertainty capabilities, leading to dramatic model improvements and validation of experiments. This paper uses state-of-the-art data assimilation techniques to obtain a best estimate of parameters critical to plant safety. Data assimilation can combine computational, benchmark and experimental measurements, propagate sparse covariance and sensitivity matrices, treat non-linear applications and accommodate discrepancies. The methodology is further demonstrated through application to hot zero power tests in a pressurised water reactor (PWR) performed using the BEAVRS benchmark with Latin hypercube sampling of reactor parameters to determine responses. WIMS 11 (dv23) and PANTHER (V.5:6:4) are used as the coupled neutronics and thermal-hydraulics codes; both are used extensively to model PWRs. Results demonstrate updated best estimate parameters and reduced uncertainties, with comparisons between posterior distributions generated using maximum entropy principle and cost functional minimisation techniques illustrated in recent conferences. Future work will improve the Bayesian inverse framework with the introduction of higher-order sensitivities. |
| first_indexed | 2024-12-16T16:12:37Z |
| format | Article |
| id | doaj.art-f46e48963f3948748b6cf776a247b7c5 |
| institution | Directory Open Access Journal |
| issn | 2100-014X |
| language | English |
| last_indexed | 2024-12-16T16:12:37Z |
| publishDate | 2021-01-01 |
| publisher | EDP Sciences |
| record_format | Article |
| series | EPJ Web of Conferences |
| spelling | doaj.art-f46e48963f3948748b6cf776a247b7c52022-12-21T22:25:11ZengEDP SciencesEPJ Web of Conferences2100-014X2021-01-012470902010.1051/epjconf/202124709020epjconf_physor2020_09020DATA ASSIMILATION APPLIED TO PRESSURISED WATER REACTORSDixon J.R0Lindley B.A.1Taylor T.2Parks G.T.3Cambridge University Engineering DepartmentWood Kings Point House, Queen Mother SquareEDF Energy Barnett Way, Barnwood, GloucesterCambridge University Engineering DepartmentBest estimate plus uncertainty is the leading methodology to validate existing safety margins. It remains a challenge to develop and license these approaches, in part due to the high dimensionality of system codes. Uncertainty quantification is an active area of research to develop appropriate methods for propagating uncertainties, offering greater scientific reason, dimensionality reduction and minimising reliance on expert judgement. Inverse uncertainty quantification is required to infer a best estimate back on the input parameters and reduce the uncertainties, but it is challenging to capture the full covariance and sensitivity matrices. Bayesian inverse strategies remain attractive due to their predictive modelling and reduced uncertainty capabilities, leading to dramatic model improvements and validation of experiments. This paper uses state-of-the-art data assimilation techniques to obtain a best estimate of parameters critical to plant safety. Data assimilation can combine computational, benchmark and experimental measurements, propagate sparse covariance and sensitivity matrices, treat non-linear applications and accommodate discrepancies. The methodology is further demonstrated through application to hot zero power tests in a pressurised water reactor (PWR) performed using the BEAVRS benchmark with Latin hypercube sampling of reactor parameters to determine responses. WIMS 11 (dv23) and PANTHER (V.5:6:4) are used as the coupled neutronics and thermal-hydraulics codes; both are used extensively to model PWRs. Results demonstrate updated best estimate parameters and reduced uncertainties, with comparisons between posterior distributions generated using maximum entropy principle and cost functional minimisation techniques illustrated in recent conferences. Future work will improve the Bayesian inverse framework with the introduction of higher-order sensitivities.https://www.epj-conferences.org/articles/epjconf/pdf/2021/01/epjconf_physor2020_09020.pdfinverse uncertainty quantificationdata assimilationwimspanther |
| spellingShingle | Dixon J.R Lindley B.A. Taylor T. Parks G.T. DATA ASSIMILATION APPLIED TO PRESSURISED WATER REACTORS EPJ Web of Conferences inverse uncertainty quantification data assimilation wims panther |
| title | DATA ASSIMILATION APPLIED TO PRESSURISED WATER REACTORS |
| title_full | DATA ASSIMILATION APPLIED TO PRESSURISED WATER REACTORS |
| title_fullStr | DATA ASSIMILATION APPLIED TO PRESSURISED WATER REACTORS |
| title_full_unstemmed | DATA ASSIMILATION APPLIED TO PRESSURISED WATER REACTORS |
| title_short | DATA ASSIMILATION APPLIED TO PRESSURISED WATER REACTORS |
| title_sort | data assimilation applied to pressurised water reactors |
| topic | inverse uncertainty quantification data assimilation wims panther |
| url | https://www.epj-conferences.org/articles/epjconf/pdf/2021/01/epjconf_physor2020_09020.pdf |
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