CATHARE (Code for Analysis of Thermalhydraulics during an Accident of Reactor and safety Evaluation) is a system-scale, two-phase

thermal-hydraulics Thermal hydraulics (also called thermohydraulics) is the study of hydraulics, hydraulic flow in thermal fluids. The area can be mainly divided into three parts: thermodynamics, fluid mechanics, and heat transfer, but they are often closely linked t ...

simulation software Simulation software is based on the process of modeling a real phenomenon with a set of mathematical formulas. It is, essentially, a program that allows the user to observe an operation through simulation without actually performing that operation ...

developed by CEA since 1979. The result of a partnership with

EDF EDF may refer to: Organisations * Eclaireurs de France, a French Scouting association * Électricité de France, a French energy company ** EDF Energy, their British subsidiary ** EDF Luminus, their Belgian subsidiary * Environmental Defense Fund, ...

Framatome Framatome () is a French nuclear reactor business. It is owned by Électricité de France (EDF) (80.5%) and Mitsubishi Heavy Industries (19.5%). The company first formed in 1958 to license Westinghouse's pressurized water reactor (PWR) designs ...

and IRSN, it has historically been used for

nuclear safety Nuclear safety is defined by the International Atomic Energy Agency (IAEA) as "The achievement of proper operating conditions, prevention of accidents or mitigation of accident consequences, resulting in protection of workers, the public and the ...

studies on

pressurized water reactors A pressurized water reactor (PWR) is a type of light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants (with notable exceptions being the UK, Japan, India and Canada). In a PWR, water is used both as ...

, as well as in training simulators for the French nuclear fleet. Its scope of use has gradually been extended to other nuclear industries, as well as to other sectors such as transport and

space propulsion Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. In-space propulsion exclusively deals with propulsion systems used in the vacuum of space and should not be confused with space launch or atmospheric e ...

. The code is involved in most reactor design projects in the French nuclear sector, whether for Generation III power reactors ( EPR, NUWARD), Generation IV reactors ( sodium-cooled fast reactors,

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

gas Gas is a state of matter that has neither a fixed volume nor a fixed shape and is a compressible fluid. A ''pure gas'' is made up of individual atoms (e.g. a noble gas like neon) or molecules of either a single type of atom ( elements such as ...

, molten-salt reactors),

research reactors Research reactors are nuclear fission-based nuclear reactors that serve primarily as a neutron source. They are also called non-power reactors, in contrast to power reactors that are used for electricity production, heat generation, or maritim ...

(

Jules Horowitz Reactor The Jules Horowitz Reactor (, ''RJH'') is a materials testing reactor (MTR) cooled and moderated with water. It is under construction at Cadarache in southern France, based on the recommendations of the European Roadmap for Research Infrastructure ...

) or naval propulsion. By default, CATHARE solves a six-equation system (conservation of mass, momentum and energy for the liquid and vapor phases), explicitly allowing for differences in velocity and temperature between phases. It features a modular multi-scale structure (0D, 1D, 3D), to adapt the discretization according to the components and type of study. The code also features numerous sub-modules, both hydraulic (

pumps A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic or pneumatic energy. Mechanical pumps serve in a wide range of applications such ...

valves A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, ...

, check valves, etc.) and thermal ( fuel rods,

heat exchangers A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contac ...

, etc.). As a result, it can model transient scenarios of complex systems with computation times close to or even less than the physical time. This is particularly useful for modeling the primary circuits of nuclear reactors in accident situations, such as

loss-of-coolant accident A loss-of-coolant accident (LOCA) is a mode of failure for a nuclear reactor; if not managed effectively, the results of a LOCA could result in reactor core damage. Each nuclear plant's emergency core cooling system (ECCS) exists specifically to ...

, which can last several hours or even days. Its latest major release, CATHARE-3, available to partners since the end of 2019, features several new functionalities. In 2020, it won the annual Grand Prix of th
French Nuclear Energy Society
Simulations using the CATHARE-3 code were carried out as part of an international working group set up by the

United Nations Environment Programme The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the Declaration of the United Nati ...

to assess

methane emissions Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane r ...

from leaking

Nord Stream Nord Stream (German–English mixed expression for "North Stream"; , ''Severny potok'') is a network of offshore natural gas pipelines which run under the Baltic Sea from Russia to Germany to provide Western Europe with natural gas. It comprises t ...

pipelines following their

sabotage Sabotage is a deliberate action aimed at weakening a polity, government, effort, or organization through subversion, obstruction, demoralization (warfare), demoralization, destabilization, divide and rule, division, social disruption, disrupti ...

in September 2022. The results of the study are published in the journal

Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...

in January 2025{{Cite journal , last1=Harris , first1=Stephen J. , last2=Schwietzke , first2=Stefan , last3=France , first3=James L. , last4=Velandia Salinas , first4=Nataly , last5=Meixus Fernandez , first5=Tania , last6=Randles , first6=Cynthia , last7=Guanter , first7=Luis , last8=Irakulis-Loitxate , first8=Itziar , last9=Calcan , first9=Andreea , last10=Aben , first10=Ilse , last11=Abrahamsson , first11=Katarina , last12=Balcombe , first12=Paul , last13=Berchet , first13=Antoine , last14=Biddle , first14=Louise C. , last15=Bittig , first15=Henry C. , date=2025-01-15 , title=Methane emissions from the Nord Stream subsea pipeline leaks , journal=Nature , volume=637 , issue=8048 , language=en , pages=1124–1130 , doi=10.1038/s41586-024-08396-8 , pmid=39814894 , pmc=11779632 , bibcode=2025Natur.637.1124H , issn=1476-4687

References

Physics software Industrial software Computational fluid dynamics Nuclear reactors

See also

References