In-service inspections are performed during regular outages of individual nuclear power plant units. An outage is a planned shutdown of a nuclear unit for the purpose of refueling and periodic inspections of equipment by suppliers based on technical documentation requirements. There is a detailed plan for each outage and its schedule is approved by all parties involved.
ŠKODA JS has had forty years of experience with pre-service and in-service inspections. On a periodic basis, we perform inspections of the reactor pressure vessel both from the inner as well as outer surface, reactor main flange bolts, welds of the main coolant piping loops and other essential primary circuit components. So far, we have carried out more than 100 pre-service and in-service inspections of reactor pressure vessels at nuclear power plants in the Czech Republic, Slovakia, Hungary, Ukraine, Germany and Armenia.
The first inspections were performed as early as in 1978, and since 1982 inspections have been performed remotely and in an automated fashion. A remote automated inspection of the reactor pressure vessel includes ultrasound testing, eddy current testing, and a visual inspection from the inner as well as outer surface. At the time of the inspection from the inner surface, the reactor vessel is filled with water, therefore all the probes, manipulator cameras and modules, motors and position sensors are water-tight.
Modular Control System (MKS)
In 2015, we put into practice for the first time a new MKS system for inspections of reactor pressure vessel bodies from inside, which can be used for VVER 440, VVER 1000, MIR.1200, AP 1000 reactors. It is a positioning device that is used to manipulate individual modules for inspection operations inside the reactor vessel.
The MKS has been developed and manufactured by ŠKODA JS.
The MKS system was used for the first time during the in-service inspection of Unit 2 of the Temelín NPP, where the fulfillment of the defined requirements was confirmed, i.e. the inspection time was shortened, assembly and disassembly were shortened and simplified, and inter-operational assembly times were shortened.
The basic part of the MKS system is a manipulator, whose task is to get test probes for detecting material defects into contact with the inner surface of the reactor. The second part of the MKS system consists of the actual testing devices, which allow non-destructive testing by ultrasonic, visual and eddy current methods.
The MKS is designed so that the part extending below the level of the main dividing plane is adapted for work in water, the upper part is adapted for decontamination by spraying. For operation, it uses its own control station with evaluation device.
Inspections of LPG tanks using the acoustic emission method
ŠKODA JS a.s. uses acoustic emission methods to check the integrity of pressure equipment, especially for checking liquefied natural gas (LPG) storage tanks.
The method used has three main advantages:
- reduces the time of a traditional hydraulic pressure test by a fifth,
- is cheaper,
- it is more environmentally friendly, as the stored medium is used during the test, eliminating the risk of leakage during overpumping and the problem of waste water disposal in the case of a hydraulic test.
The history of our cooperation
1982 the first remote and automated inspection of a reactor pressure vessel performed at the Bohunice NPP, Slovakia
1997 the first inspection of welds of the main coolant piping loop performed at the Dukovany NPP
2011 the first inspection of heat transfer pipes of the steam generator performed at the Dukovany NPP
2015 the first application of the MKS manipulator (of our own design) during an in-service inspection of Unit 2 of the Temelín NPP
2016 the first inspection of heat transfer pipes in the exchangers and coolers performed at the Temelín NPP
1984-2020regular inspections of the reactor pressure vessel performed at the Dukovany NPP
2000-2020regular inspections of the reactor pressure vessel performed at the Temelín NPP
6 years of inspections of heat transfer pipes in exchangers and coolers