Quantification of LOCA core damage frequency based on thermal-hydraulics analysis

Cho, Jaehyun; Park, Jin Hee; Kim, Dong-San; Lim, Ho-Gon

doi:10.1016/j.nucengdes.2017.02.023

Cited by 15 publications

(3 citation statements)

References 5 publications

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“…Examples, among many reported in the literature, that employ or extend Rasmussen's work include Zhang et al (2021) who argue that the cost and benefit of safety enhancements can be in part evaluated against predicted CDF. Cho et al (2017) describe how, based on CDF, some protections are less important than others. Williams et al (2018) describe a method that integrates prediction of conditional probability of core damage events with predicted frequency of core damage.…”

Section: Overviewmentioning

confidence: 99%

On the Optimistic Bias of Core Damage Frequency, and why it should be excluded from nuclear regulatory requirements.

Wortman¹

2021

Preprint

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Core Damage Frequency (CDF) is a risk metric often employed by nuclear regulatory bodies worldwide. Numerical values for this metric are required by U.S. regulators, prior to reactor licensing, and reported values can trigger regulatory inspections. CDF is reported as a constant, sometimes accompanied by a confidence interval. It is well understood that CDF characterizes the arrival rate of a stochastic point process modeling core damage events. However, consequences of the assumptions imposed on this stochastic process as a computational necessity are often overlooked. Herein, we revisit CDF in the context of modern point process theory. We will argue that the assumptions required to yield a constant CDF are typically unrealistic. We will further argue that treating CDF as an informative approximation is suspect, because of the inherent difficulties in quantifying its quality as an approximation.

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Section: Overviewmentioning

confidence: 99%

On the Optimistic Bias of Core Damage Frequency, and why it should be excluded from nuclear regulatory requirements.

Wortman¹

2021

Preprint

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“…The preference of RPV must have the capability, internal pressure rating, corrosion resistance and design features suitable for intended use [5]. When the RPV cannot function to maintain the helium gas that occupies the gap between the core barrel and the inner shell wall, this phenomenon does not cause fuel heat to rise inside the core and this cannot ultimately meltdown the reactor core, unlike in the case study of nuclear accident in Japan when the pressure vessel is malfunction, heat continues to accumulate in the reactor and then the core meltdown and damaged [6][7][8]. Other than that, neutron irradiation embrittlement reduces the fracture toughness of RPV materials during plant operation [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Buckling Analysis of Circular Shells for RDE Reactor Pressure Vessel by Finite Element Study and Analytical Model

Sudadiyo

2020

Jurnal Pengembangan Energi Nuklir

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Eksperimental (RDE) is buckling mode shape of geometric structure imperfections. Geometric structure is prone to a large number of imperfections due to the manufacturing difficulties. Moreover, determination of critical loads of circular shell structure can be properly approximated only through randomness in the geometry. As at the basic design phase this is possible and expensive to measure the geometric structure imperfections in situ or in laboratory, a simulation of computer code should be provided. In this paper, a contribution is made to numerical simulation by finite element study and analytical model by Monte Carlo technique approach of such circular shells for RPV components. For this reason, computer code SolidWorks is used in the implementation finite element analysis and Fortran code is developed for analytical model analysis. The main objective of this investigation is to provide a comprehensive analysis of unstable structure due to the buckled geometric imperfection in the design calculations involved. A method of solution attempts to use the linearized equilibrium equations to interpret geometric imperfections as structure of circular shells associated with the RPV components of RDE. A number of calculation results carried out on a computer code are presented to illustrate the design of RPV components that are safe from the buckled shape failure. It is found that both of the computer code results are very similar with greatest difference value of vibrational amplitude of 0.00699 % and smallest value for buckling load factor of 12.51 on upper circular shell under 750 C conditions. ABSTRAK ANALISIS TEKUK SEL SILINDER UNTUK BEJANA TEKAN REAKTOR RDE DENGAN STUDI ELEMEN HINGGA DAN MODEL ANALITIS.Salah satu pertimbangan desain dasar untuk sel silinder komponen Reactor Pressure Vessel (RPV) dari Reaktor Daya Eksperimental (RDE) adalah bentuk mode tekuk ketidaksempurnaan struktur geometri. Struktur geometris rentan terhadap sejumlah besar ketidaksempurnaan akibat kesulitan dalam manufaktur. Selain itu, penentuan beban kritis struktur sel silinder hanya dapat didekati dengan tepat melalui keacakan dalam geometri. Karena pada fase desain dasar ini adalah mungkin dan mahal untuk mengukur ketidaksempurnaan struktur geometris di bengkel kerja atau di laboratorium, simulasi kode komputer harus disediakan. Dalam tulisan ini, kontribusi dibuat untuk simulasi numerik dengan studi elemen hingga dan model analitis dengan pendekatan teknik Monte Carlo dari sel-sel melingkar untuk komponen RPV. Untuk alasan ini, kode komputer SolidWorks digunakan dalam pelaksanaan analisis elemen hingga dan kode Fortran dikembangkan untuk analisis model analitis. Tujuan utama dari penelitian ini adalah untuk memberikan analisis yang komprehensif dari struktur yang tidak stabil akibat ketidaksempurnaan geometrik tekuk dalam perhitungan desain yang terlibat. Metode penyelesaiandengan menggunakan persamaan kesetimbangan linierisasi untuk menginterpretasikan ketidaksempurnaan geometris sebagai struktur sel silinder yang terkait dengan kom...

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mentioning

confidence: 99%

Is Core Damage Frequency an Informative Risk Metric?

Wortman¹,

Kee²,

Kannan³

2021

Preprint

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Core Damage Frequency (CDF) is a risk metric often employed by nuclear regulatory bodies worldwide. Numerical values for this metric are required by U.S. regulators, prior to reactor licensing, and reported values can trigger regulatory inspections. CDF is reported as a constant, sometimes accompanied by a confidence interval. It is well understood that CDF characterizes the arrival rate of a stochastic point process modeling core damage events. However, consequences of the assumptions imposed on this stochastic process as a computational necessity are often overlooked. Herein, we revisit CDF in the context of modern point process theory.We will argue that the assumptions required to yield a constant CDF are typically unrealistic.We will further argue that treating CDF as an informative approximation is suspect, because of the inherent difficulties in quantifying its quality as an approximation.

show abstract

Quantification of LOCA core damage frequency based on thermal-hydraulics analysis

Cited by 15 publications

References 5 publications

On the Optimistic Bias of Core Damage Frequency, and why it should be excluded from nuclear regulatory requirements.

On the Optimistic Bias of Core Damage Frequency, and why it should be excluded from nuclear regulatory requirements.

Buckling Analysis of Circular Shells for RDE Reactor Pressure Vessel by Finite Element Study and Analytical Model

Is Core Damage Frequency an Informative Risk Metric?

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