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

4.1 Loviisa NPP
One event occurred in 2011 in intermediateand
low-level waste management. It was detected
at the Loviisa power plant in early 2011 that
the seepage water collection system of the low-level
waste repository contained small amounts of radioactive
tritium. Radioactivity had escaped into
the system when the drain pipe for water dropping
from the ceiling had become blocked and water
had run on some waste barrels. The event had no
impact on the safety of personnel or the environment.
Following the event, Fortum replaced the
drain pipes of the seepage water collection funnels
on the ceiling of the repository. The activity of seepage
water and condensation water in the ventilation
system is closely monitored.
The project implementation schedule has now
been further specified so that the installations of
phase 2 will be made in 2014 for Loviisa 1. In deviation
from the earlier schedule, the whole I&C
upgrade of Loviisa 1 will be completed in 2015
before the installations at Loviisa 2 begin in 2016
and 2017.
Modernisation of refuelling machines
Fortum is in the process of modernising the refuelling
machines at the Loviisa power plant. The
modernisation project will include a basic upgrade
of the electrical and I&C systems of the refuelling
machine, now based on 1970s technology, as well
as a possible increase in the height of the machine.
The latter can be implemented either by modernising
the existing machine or by replacing it. The
main reason for increasing the height of the bridge
is that it would allow installing permanent safety
rails at the fuel pools. Provisions also exist for extending
the rails of the refuelling machine. This
would allow re-routing the heavy load lifts in the
reactor hall, thus reducing the risk of core damage
caused by falling loads. Fortum submitted a conceptual
modernisation plan for the refuelling machine
to STUK in June 2010. STUK reviewed the
conceptual design plan and required additions to
be made to it with respect to, among other things,
quality management, systems classification and
the I&C qualification plan. STUK approved the
conceptual design plan with remarks in November
2011. Fortum submitted an updated I&C qualification
plan to STUK at the end of the year.
STUK-B 147
Quantities of spent fuel and lowand
intermediate-level waste
The volume of spent nuclear fuel stored on-site
at the Loviisa power plant at the end of 2011
was 4,339 assemblies* (522 tU), an increase of
192 assemblies (23 tU). The volume of low- and
intermediate-level waste finally disposed of was
1,774 m³. The total increase of volume from 2010
is 93 m³. Approximately 50% of the waste has been
finally disposed of.
* The assembly figures do not include the assemblies
in the reactors. The average weight of
spent fuel assemblies at the Loviisa power plant
is 120.3 kgU.
4.1.6 Spent nuclear fuel storage and low-
and intermediate-level waste
STUK reviewed, in accordance with the inspection
programme, the low- and intermediate-level waste
management and final disposal of waste materials
at the Loviisa power plant. The inspection of
low- and intermediate-level waste management focused
on the situation of the project for developing
the handling of low- and intermediate-level waste,
the arrangements at the liquid waste solidification
facility, waste accounting, organisation and
instructions. Following the inspection observations,
STUK required the Loviisa power plant to assess
the rusting and corrosion mechanism of low-level
waste barrels placed in the VLJ repository, as well
as the impacts that the deteriorating condition of
the barrels will have on nuclear waste management
and its safety.
In October, STUK carried out an inspection of final
disposal facilities for waste at the Loviisa power
plant. It covered the maintenance procedures at
the plant site, the repairs and modifications carried
out and the results of inspections performed
by the power company. The latter also included the
results of groundwater chemistry measurements
taken from the bedrock of the disposal facility,
as well as the hydrological and rock-mechanical
monitoring measurements. No requirements were
imposed following the inspections.
The processing, storage and final disposal of
low- and intermediate-level waste (so-called operating
waste) at the Loviisa power plant were
carried out as planned. The volume and activity
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