Coupling Codes – Wrappers

One of the main BABIECA features is the possibility to manage different simulation codes that allow communication between them.

An accidental sequence involves a broad phenomenology that almost never can be found in a single code. To analyze the underlying multiphysic analysis of a transient in a central process simplifies the necessary methodology, helps the error management and improves the analysis performance. To this end there were incorporated to BABIECA two modules that help manage code coupling.

To couple a specific code, BABIECA need that it incorporates a protocol to send and receive both continuous and discrete variables and understand the meaning of these.

Coupled codes

SndCode and RcvCode are the modules that handle the communication. SndCode provides the boundary conditions and RcvCode is responsible for receiving the calculated results during time step advancement.

In this framework, we have developed four wrappers of external codes:

  • MAAP4. Wrapper that allows connections BABIECA – MAAP4. This coupling gives us the advantage of analyzing sequences MAAP4 with tools developed for BABIECA.
  • BABIECA. Wrapper that allows BABIECA engage himself, and is used to split large topologies into smaller ones in order to save computation time due to parallelization of processes.
  • TRACE. This connection will allow us to perform simulations with SIMPROC validation SOPs and times available.
  • SIMPROC. It has been added to SCAIS as a library couplet to Babieca. It allows us to simulate the control crew of a plant and verificate POEs and SAMGs.

MAAP: Modular Accident Analysis Program

MAAP. Is a thermalhydraulic code specialized in the treatment of severe accidents in light water reactor LWR. It has been developed by EPRI, USA electrical industry and is one of the most used by industry worldwide for regulatory safety analyzes.

MAAP was developed for modeling thermal-hydraulic behavior of fission products in the Primary System and containment systems. A notable feature of MAAP is its flexible system that allows modeling operator actions with safety systems to simulate a realistic accident, including the ability to recover systems.

MAAP solves a set of equations representing mass, energy and momentum in different parts of the system. MAAP is capable of solving a wide range of phenomena, such as steam generation tube breaks, hydrogen generation…

The sequences may lead to a safe state or to containment failure. In this sense, is one of the best codes for PSA2.

TECNATOM coupled it to their control rooms to perform simulations of a severe accident with operators in real time. It is the code that is currently being used as plant code in applications with SCAIS.

Applications carried out since 2008 with SCAIS-MAAP have been focused on simulating with MAAP until core damage time. It may seem paradoxical to use a specific code to simulate severe accident only until this occurs. The reason is that it is much faster than detail codes as TRACE, and allows us to make qualitative analyzes that have been of great value. Furthermore it has also been observed that in most cases the results recognized as damaged MAAP envelopes which are considered as damage TRACE (of course this assumption is not valid for regulation purposes, but is good enough for research).

The full DET of an accident can be performed in a very short time, which would not be possible to detail codes.

During last year, due to the increasing interest in severe accident analysis, SCAIS is being used for dose analysis in severe accident trying to analyze Severe Accident Management (SAMGs).

SIMPROC potential for timing analysis of operator strategies and procedures is still untapped. An application in which SIMPROC management performing a systematic analysis of the EOPs and the transition to SAMGs  with the workloads and disposal times for each task will challenge the correct use of procedures and guides.

BABIECA-MAAP conection is outlined in the figure below and follow the paradigm of standardization coupling codes designed by CSN MOSI group.

Among others, one of the most important applications of this period was:

-A code for the simulation of human failure events in nuclear power plants: SIMPROC (Esrel 2008). It was the first public presentation of SIMPROC.

The application simulates operator actions on the level of control of the steam generator for a transitional MBLOCA. These actions include POE ES-1.2, cooling and depressurization.

After that, many applications were developed and SIMPROC evolved until SM2A project (briefly discussed in chapter projects) presented at the conference Nuclear Energy for the New Europe (NENE). A paper with the same title but a much more complete application. Following the presentation in Slovenia, the journal Nuclear Energy and Design (NED) invited us to extend the article.

The picture left above shows different moments that lead to depressurization transients that exceed the PCT and others not showing the time available in a particular sequence.

On the right is the damage domain generated for different points of high pressure injection system (HPSI) recovery  with different times of depressurization.

Connecting SCAIS-TRACE. Using External Communication Interface. ECI

TRACE code is designed for  primary and secondary transient simulations of a nuclear reactor.

Code developers added a communication interface that allows coupling TRACE in a very detailed way to other codes in order to simulate a broad range of phenomena.

After an analysis of the capabilities of this interface (ECI) it was decided to use it for coupling to SCAIS system.

SCAIS  coupled to a Best Estimated code as TRACE opens a wide range of applications that can be performed. This connection has not yet been tested accurately, but allow us to perform analysis of EOPs if used  connected to SIMPROC , as shown in the application presented in 2011 at the SNE. [5] by performing a simulation with operator actions in a sequence of LOCA.