Regulatory oversight of nuclear safety in Finland. Annual ... - STUK

ing that the nuclear power plant is safe during the
annual maintenance and future operating cycles,
and that the annual maintenance does not cause a
radiation hazard to the workers, the population or
the environment. STUK ensures this by reviewing
the documents required by the regulations, such as
outage plans and modification documentation, and
by performing on-site inspections during annual
maintenance.
Plant maintenance and ageing management
In its regulatory activities concerning the ageing
management of operating nuclear facilities, STUK
controls the plants’ ageing management strategy
and its implementation ensures the maintenance
of sufficient safety margins for safety-significant
systems, components and structures throughout
their lifetime. The organisation of the licensee’s
operations, the prerequisites for the organisation
to carry out the necessary actions, and the condition
of components and structures important to safety
are subject to inspection and review. Regulatory
control and inspections ensure that the power companies
have the lifetime management programmes
in place that enable them to detect potential problems
in time. In addition, corrective action must be
carried out in a way that ensures the integrity and
operability of safety-significant components and
structures so that safety functions can be activated
at any time.
STUK monitors ageing management through
the inspections of the periodic inspection programme
and inspections related to modifications and
annual maintenance. The key issue in operation
licence renewal and periodic safety assessments is
the management of plant ageing.
Every year, the power companies provide STUK
with reports on the ageing of electrical and I&C
equipment, mechanical structures and equipment,
as well as buildings. These reports describe the
most salient ageing phenomena to be monitored,
observations related to the ageing process and
actions required for extending the service life of
equipment and structures.
The licensee must carry out periodic inspections
of safety-critical equipment and structures
(such as the reactor pressure vessel and reactor
coolant system). STUK approves the inspection
programmes prior to the inspections and monitors
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the inspections and their results on site. The final
result reports will be submitted to STUK for approval
after the annual maintenance.
Radiation safety
STUK oversees occupational radiation safety by
inspecting and reviewing dosimetry, radiation
measurements, radiation protection procedures,
radiation conditions and radiation protection arrangements
for work processes at each facility. The
dosimeters used for measuring the occupational radiation
doses undergo annual tests carried out by
STUK. The test comprises irradiating a sample of
dosimeters at STUK’s measurement standard laboratory
and reading the doses at the power plant.
In addition, STUK oversees the meteorological dispersion
measurements of radioactive substances,
release measurements and environmental radiation
monitoring, and also reviews the relevant result
reports.
Emergency preparedness
Besides the periodic inspections of other operations,
STUK controls the readiness of the organisations
operating nuclear power plants to act in
abnormal situations. The inspection focuses on
training in emergency response organisation, arrangement
of rooms, securing the connections used
for the transfer of meteorological measurement
data during an emergency situation and radiation
monitoring of the surrounding environment,
as well as the development of internal alarm procedures
at the power plant. Emergency exercises test
the operation of the emergency response organisation,
the functionality of the emergency response
guidelines and the usability of the alert areas in
practice, which are developed on the basis of the
feedback received for the exercises. STUK monitors
the actions of power companies during these
emergency drills.
Monitoring the operation of organisations is
part of the process of ensuring plant safety
STUK oversees the operation of organisations by
reviewing safety management, the management
and quality systems, the competence and training
of the staff of nuclear facilities and operational
experience feedback activities. The aim is to ensure
that the organisations of the power company as a
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