Markus Niffenegger

Paul Scherrer Institute

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Guian Qian

Institute of Mechanics

V.F. González‐Albuixech

Universidad Politécnica de Madrid

Medhat Sharabi

University of Nottingham

Bojan Ničeno

Paul Scherrer Institute

Nathan Lafferty

ETH Zurich

D. Kalkhof

Swiss Federal Nuclear Safety Inspectorate

K. Reichlin

Paul Scherrer Institute

Roman Mukin

ABB (Switzerland)

Diego F. Mora

Paul Scherrer Institute

Gaojun Mao

Paul Scherrer Institute

Cooperative Institutions

Paul Scherrer Institute

École Polytechnique Fédérale de Lausanne

ETH Zurich

Madrid Institute for Advanced Studies

Hohai University

Oak Ridge National Laboratory

Nuclear Research Institute Rez (Czechia)

Framatome (Germany)

Jožef Stefan Institute

Chinese Academy of Sciences

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Fracture Toughness, Thermo-Electric Power, and Atom Probe Investigations of JRQ Steel in I, IA, IAR, and IARA Conditions

Journal of ASTM International (2005)

RK Nanstad Markus Niffenegger RD Kalkhof M.K. Miller MA Sokolov

Abstract The International Atomic Energy Agency has sponsored a number of studies involving a specific plate of A533 grade B class 1 steel designated heat JRQ. In this cooperative study between the Paul Scherrer Institute (PSI) and the Heavy-Section Steel Irradiation Program of Oak Ridge National Laboratory (ORNL), groups of Charpy impact, tensile, and precracked Charpy specimens of the JRQ plate were irradiated by PSI to four different fast neutron fluences [from 0.39 to 5.0 × 1023 n/m2 (>1 MeV)] in a test reactor. Additional specimens were given a post-irradiation thermal annealing treatment at 460°C for 18 h when 50 % of the target fluence was reached, followed by reirradiation to the same target fluences for the four groups of irradiated specimens. Additionally, ORNL thermally annealed some of the reirradiated specimens, as well as some of those in the irradiated only condition. Charpy impact, tensile, fracture toughness, and hardness tests have been performed to evaluate material response in the various conditions and to compare with the unirradiated material. Additionally, thermo-electric power experiments have been conducted by PSI, while atom probe tomography evaluations have been conducted by ORNL. Except at the highest fluence, the results show that the material given an intermediate annealing treatment exhibited irradiation-induced transition temperature shifts about the same as those that were only irradiated. However, the upper-shelf energies were generally higher and the yield strengths were generally lower for the reirradiated groups. The intermediate thermal annealing resulted in less reirradiation embrittlement of fracture toughness than Charpy impact toughness, while annealing after reirradiation resulted in significant increases in Charpy upper-shelf energy above that in the unirradiated condition. Irradiation-induced and IAR Charpy impact transition temperature shifts exhibit a nearly linear correlation with Seebeck coefficient in the I and IAR conditions. ORNL has also sent additional specimens from I, IA, IAR, and IARA test of JRQ for additional TEP testing. After irradiation, a high number density of ultrafine Cu-, Mn-, Ni-, Si-, and P-enriched precipitates were observed by atom probe tomography. Phosphorus segregation to dislocations was also observed. A significantly lower number density of larger Cu-, Mn-, and Ni- enriched precipitates was observed after the second annealing treatment.

Charpy impact test

10.1520/jai12888

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Citations (15)

Investigation on crack initiation, propagation, and arrest in thick-walled cylinders under thermal-shock loading

Engineering Fracture Mechanics (2024)

Diego F. Mora Guo-qing Mao Markus Niffenegger

Thermal shock

10.1016/j.engfracmech.2024.110775

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Computational Analyses of the Thermal Stress Induced by Coolant Mixing in a T-Joint

Volume 1: Plant Operations, Maintenance, Engineering, Modifications, Life Cycle and Balance of Plant; Nuclear Fuel and Materials; Plant Systems, Structures and Components; Codes, Standards, Licensing and Regulatory Issues (2014)

Maddy Janssens Markus Niffenegger Medhat Sharabi

In this paper we report computational fluid dynamics and thermal stress finite element analyses of a T-joint component as used in a Swiss nuclear power plant under realistic loading conditions and simplified boundary conditions. In this report the focus is on the thermal stress analyses, and therefore only those fluid dynamics simulations used for thermal stress analyses are presented. The local stress amplitudes, simulated using elastic finite element simulations, are compared to a regulatory fatigue life curve to estimate the local distribution of low cycle fatigue damage and crack initiation probability in the T-joint. The case studies reported here have been selected with the purpose of analyzing the different ways in which the fluid structure interaction induces thermal stress in the mixing tee. In case I only the thermal stress induced by the mixing turbulence is simulated, i.e. with constant mass flow rate boundary conditions. In case II a peak in the flow rate in the main pipe, typical for transient (startup) plant conditions, is addressed and analyzed in detail. Only in the latter case is low cycle fatigue cracking to be expected in the form of non-propagating (i.e. not throughwall) surface cracks or crazing.

10.1115/icone22-30218

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Intelligent Code for Assessing Performance and Reliability of Failure Assessment Models

Journal of Pipeline Systems Engineering and Practice (2025)

Guo Lingyun Wang Hexian Bo Chen Markus Niffenegger

Code (set theory)

10.1061/jpsea2.pseng-1755

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Integrity analysis of a reactor pressure vessel subjected to pressurized thermal shocks by considering constraint effect

Engineering Fracture Mechanics (2013)

Guian Qian Markus Niffenegger

Thermal shock

10.1016/j.engfracmech.2013.09.009

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Citations (55)

Monitoring of low-cycle fatigue degradation in X6CrNiTi18-10 austenitic steel

Journal of Nuclear Materials (2001)

M. Große Markus Niffenegger D. Kalkhof

Austenitic stainless steel

Diffusionless transformation

Low-cycle fatigue

10.1016/s0022-3115(01)00547-5

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Citations (20)

Microstructural aspects of low cycle fatigued austenitic stainless tube and pipe steels

Materials Characterization (2007)

Hans J. Leber Markus Niffenegger B. Tirbonod

Volume fraction

Austenitic stainless steel

Isothermal process

Diffusionless transformation

Lüders band

10.1016/j.matchar.2007.05.011

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Citations (34)

Comparison Of Calculated And Measured Strains In The Microstructure Of Steel 316L

Markus Niffenegger Herrera-Solaz

Source

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Integrity analysis of a reactor pressure vessel with quasi laminar flaws subjected to pressurized thermal shocks

Nuclear Engineering and Design (2014)

V.F. González‐Albuixech Guian Qian Markus Niffenegger

Thermal shock

Structural integrity

Pressurized water reactor

10.1016/j.nucengdes.2014.09.035

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Citations (11)

Probabilistic Pressurized Thermal Shocks Analysis for a Reactor Pressure Vessel by Considering Plume Effect

Guian Qian V.F. González‐Albuixech Markus Niffenegger Medhat Sharabi

The inner surface of a reactor pressure vessel (RPV) is assumed to be subjected to pressurized thermal shocks (PTSs) caused by the downstream of emergency cooling water. The downstream is not homogeneous but typically in a plume shape coming from the inlet nozzles. In this paper, both deterministic and probabilistic methods are used to assess the integrity of a model RPV subjected to PTS. The FAVOR code is used to calculate the probabilities for crack initiation and failure of the RPV considering crack distributions based on cracks observed in the Shoreham and PVRUF RPVs. The study shows that peak KI of the cracks inside the plume increases about 33% compared with that outside. The conditional probability inside the plume is more than eight orders of magnitude higher than outside the plume. In order to be conservative, it is necessary to consider the plume effect in the integrity assessment.

Pressurized water reactor

10.1115/pvp2015-45963

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