NPP,
Inspection &
Maintenance
By František Kr
č
ek, ŠKODA JS a.s.
František Kr
č
ek
František Kr
č
ek graduated from
the University of Technology in
Brno (Faculty
of Mechanical
Engineering) in
1995. From 1996
to 2008 he worked
at Czech Power
Company
Č
EZ,
a.s., where he held
various positions
in Primary Circuit
teams, he concluded
his work as the
Primary Circuit
Coordination
working group
leader.
Since 2009 he has worked at ŠKODA JS
a.s., where he began as the Head of the
Temelín NPP Department.
He has been the NPP Services Division
Director in ŠKODA JS a.s. since 2011.
ŠKODA JS is the general supplier
of maintenance services for the nuclear
islands of both of the Czech Republic’s
nuclear power plants –Temelín and
Dukovany. There are a total of 6
production units at the two plants.
Under the contract with the power
plant operator
Č
EZ, a.s., ŠKODA JS,
using its own employees or qualified
staff of technical service providers
in the supply chain, ensures the
preparation, performance and evaluation
of the maintenance of the nuclear
island equipment, including inspections
required by the regulatory authority.
Approximately two-thirds of the
activities are performed by the company’s
own staff; the rest
is performed by
qualified contractors
to
the
highest
standards possible,
using the services
of manufacturers of
a variety of primary
circuit equipment.
Ma i n t e n a n c e
services at power
plants include the
preparation and per-
formance of planned
(preventative
and
predictive) and corrective maintenance,
the majority of which takes place during
the outages of production units. These
include regular inspection activities, gen-
eral and regular equipment repairs, the
repair or replacement of damaged and
dysfunctional components or those that
fail to meet inspection requirements,
obligatory inspections and tests, as well
as activities connected with coordination
of the supply chain and expert, consult-
ing and production activities. ŠKODA
JS ensures detailed preparation of these
activities, whether it be on the technical
level (procedures, technical solutions,
blueprints, calculations), administrative
level (permits, qualification documents),
or the inspection level (inspection and
test plans, checklists). An integral part of
maintenance is also its evaluation, pro-
posals for changes and innovations, the
assessment of discovered indications and
cooperation in resolving them, as well as
close collaboration with the company that
operates the power plant in the areas of
equipment maintenance planning, techni-
cal inspections, investigation of events,
scheduling, and job performance quality.
Using its own staff or through con-
tractual partners, ŠKODA JS also con-
ducts a number of innovative activities,
such as the replacement of control rod
linear stepper drives (the components of
the safety and control system of a nuclear
reactor), the supply of reactor main flange
joint stud tensioners and upper block
flange joint stud tensioners, the produc-
tion and delivery of casks for spent nucle-
ar fuel, special shielded containers, etc.
In-service inspections
The activities of ŠKODA JS include
the assembly work itself connected
with equipment inspections as well
as installations of new technological
equipment and the performance of non-
destructive tests.
The history of in-service inspections
at ŠKODA JS dates back to 1971, when a
small group specialized in the in-service
inspection of the first Czechoslovak
nuclear power plant, A1, was formed.
At present, ŠKODA JS personnel
perform in-service inspections of the
following primary circuit components:
Reactor pressure vessel
Reactor pressure vessel closure head
Studs and nuts of the main flange
connection (M140x6 or M170x6)
Reactor internals - core barrel, core
shroud and protective tubes unit
(PTU)
Steam generator heat exchanging
tubes
Primary piping welds
Three testing methods are used for
the automated testing of primary circuit
components of Czech nuclear power
plants – ultrasonic, eddy current and
visual.
Ultrasonic testing
Ultrasonic pulse echo is the principal
non-destructive technique used for the
automated testing of VVER reactor
components. Longitudinal wave and
shear wave probes of several different
angles are used for the testing. Testing
by angle probes is usually done in four
directions – two parallel with and two
perpendicular to the weld axis, so that
the whole tested volume is covered and
flaws in all possible orientations can be
detected with the highest probability.
40
NuclearPlantJournal.com Nuclear Plant Journal, March-April 2015
