Component lifetime management
The program of controlled ageing represents a system of activities resulting in the evaluation of the actual state of straining of individual components and consequently in the analysis of their residual lifetime. The program is generally aimed at decreasing the level of damaging the equipment material throughout the operation period so that:
- the equipment material would reliably and safely resists the strain, which is related to ordinary conditions of operation
- the costs related to the maintenance and repairs of the equipment, whose material was damaged by the strain, were acceptable for the operators
- by means of investing reasonable expenses into the analysis of the actual state, repairs, replacement or reconstruction after finishing the operating time it would be possible to operate the equipment safely and reliably beyond the expected operation period
Structural safety, equipment lifetime
SKODA JS performs analyses and tests in the field of material integrity and equipment lifetime. Based on its experience in material research, manufacture development and in-service inspections, SKODA JS offers services whose aim is improving safety and extending reactor lifetime.
Measurements
SKODA JS provides thermal-hydraulic, stress analysis, radiation and diagnostic measurements.
Recovery annealing of the reactor pressure vessel
Radiation embrittlement of the reactor pressure vessel is considered a problem with some older nuclear reactors. Due to recovery annealing, mechanical properties of the base material can be renewed, which results in the extension of the reactor pressure vessel lifetime. ŠKODA JS has developed and manufactured an electrical annealing furnace and in cooperation with Slovak company VUJE a.s., it has carried out the process of annealing of two reactor pressure vessels VVER 440/V-230 type for nuclear units at Bohunice NPP and Unit 1 at Loviisa NPP in Finland. The above pressure vessels were not manufactured in SKODA JS.
The actual annealing process is highly demanding as it takes more than 100 hours, during which the annealing temperature has to be maintained within strict limits. SKODA JS has experience in the above method and can provide expert assistance in the development of technology and annealing programmes for other reactor types.
Calculations
ŠKODA JS provides stress and lifetime, neutron-physical, radiation safety and thermal-hydraulic calculations.
The department of Strength and Lifetime
- temperature calculations –temperature distribution for different sources of heat and different types of its transfer, stationary and non-stationary solutions
- stress calculations - linear calculations as well as calculations with non-linearities in compliance with Czech, Russian and US standards
- stability calculations - for thin-walled shell and rod-shaped structures, the safety against a break down at given load is determined
- dynamic calculations – frequency-modal ones, construction tuning outside resonance excitation zones, complex non-linear processes and seismic calculations
- calculations of fast dynamic processes - body drop and impact
- evaluation of the actual utilized lifetime of individual machinery components, including nuclear plant components, depending on recorded operational modes
For the given types of problems we use the ABAQUS Standard, ABAQUS Explicit and COSMOS/M program.
The department of Physics
- calculations and design of safety documentation on the RG1.70 level, covering the zone of normal and abnormal operational conditions
- studies and expertises in the field of VVER-type reactor core calculations
- project opponencies in the field of VVER-type reactor core calculations
- development and upgrade of programs for neutron-physical calculations of reactor cores operating at Dukovany NPP
- technical assistance to nuclear power plants
- development and maintenance of the SCORPIO-family monitoring systems
- development of the computing apparatus for the reactor core calculations
- analyses and design of safety documentation for the projects of casks and spent fuel storage facilities
The department of Radiation Safety
- shielding calculations
- transport calculations of neutron and gamma radiation fields and the functionals derived
- design of casks for radioactive waste and spent fuel storage
- determining accident source elementsbalance of activities in spent fuel and
- corresponding functionals: residual heat sources, gamma radiation sources, neutron sources
- balance of fission products activities in hermetical areas during an accident
- diffusion of activities outside the nuclear power plant, including the evaluation of impact of radioactive waste on public
- study of decommissioning of a nuclear power plant
- drafts of measures for the handling with radioactive materials
- optimisation of the cask loading proces
- calculation of fast neutrons fluences in the area of the reactor pressure vessel or surveillance samples, according the actual course of operation
- accident analyses
The department of Thermal-hydraulics
- calculation analyses of stationary thermal-hydraulic conditions along the general pressurized water circuit, respecting all its branching and resistive characteristics, work characteristics of circulating pumps, incorporated heat exchangers and other energy sources/underflows or the amount of work medium
- determining stationary thermal-hydraulic properties of VVER 440-type units in both nominal and non-nominal modes
- development and maintenance of the thermal-hydraulic modulus of the MOBY-DICK macrocode and the SCORPIO monitoring system and the methods for determining cassette allowed heat-up at Dukovany NPP
- solving the course of environmental parameters in the containment, or in the system of hermetic areas with a bubble condenser system, triggered by the emergency escape of primary coolant
- energy balances and calculation inspections of the cooling (systems) of spent fuel storage pools
- solving stationary and non-stationary flow and temperature fields of temperature and current of compressible and non-compressible liquids in 1D, 2D, 3D geometry of the solved area
- temperature calculations for the design and licensing of spent fuel transport and storage casks
- service calculation and consultation services
Photogallery on the topic
Furnace for recovery annealing of reactor pressure vessel
Distribution of temperature upon reactor pressure vessel annealing
Example of thermohydraulic calculations
