Quality and validation

Quality management

Apros is used in industries and applications where quality requirements are exceptionally high. Apros was originally developed for demanding use in safety and licensing analyses of nuclear power plants. Version management, documentation and code verification and validation are primary focus areas in code development.

The developers of Apros, VTT (Technical Research Centre of Finland) and Fortum Power and Heat Oy, both have ISO9001 certified quality systems.

Validation and verification of Apros calculation

The performance of the Apros code has been validated extensively (more than 70 cases) by modelling different test facilities and comparing calculation results to a large set of measurements from selected transients. The thermal hydraulic models have been validated against a set of separate effect tests and integral tests (integral tests mean e.g. test facility experiments, such as ISPs – International Standard Problems). The thermal hydraulic and reactor models together with the automation system have been thoroughly tested by comparing calculation results with real plant data.

See the list of all validation cases:

Apros Validation – Selected validation cases related to nuclear safety analysed and training simulators. 18 pages.

With every major version release a big number of cases are calculated to ensure that all the models calculate flawlessly:

Validation cases used regularly at each Apros version change

Separate effects testsPower plant models
Edwards pipe

Battelle top blow-down experiment

Becker’s experiments

ERSEC reflooding test

Marviken critical flow tests

Liquid blow-down to containment

Blow-down experiment MX-II at Marviken containment facility

Spray experiment (ISP-35) at NUPEC containment facility

Steam condensation experiment (ISP-47) at Mistra containment facility

Water level rise transient in Pactel Pressurizer

 

LOVIISA NUCLEAR POWER PLANT

  • Stopping of main recirculation pump
  • Reactor scram
  • Small break LOCA
  • Stopping of three main recirculation pumps with modified end: 3D-neutronics test

VVER-440 NUCLEAR POWER PLANT

  • Stopping of main recirculation pump
  • Reactor scram

OLKILUOTO 1 NUCLEAR POWER PLANT

  • Steam line break
  • Reactor scram

FORSMARK 3 NUCLEAR POWER PLANT (HAMBO-model)

  • Electric load rejection
  • Turbine trip, turbine bypass fails
  • Loss of condenser vacuum
  • Trip of all recirculation pumps
  • Feed-water line break, ATWS
  • Steam line break

LOVIISA ICE CONDENSER CONTAINMENT

  • Results of Large Break LOCA

CCGT POWER PLANT MODEL WITH DISTRICT HEATING CIRCUIT

  • Power set point change