14.05.2008 Lauri Myllyvirta

2007 annual report from Finnish nuclear safety authority STUK reveals that violations of quality and safety requirements have continued in Olkiluoto. These violations put into question the safety and reliability of the reactor and are likely to lead to new delays and cost overruns.

During 2007, defects in welding and other construction have still been
found. Many subcontractors still lack adequate training and understanding of
nuclear safety. Because of time pressure, manufacturing of some components was
started before the designs had been approved by the authorities and components
have been brought to inspection before they are finished.

***HIGHLIGHTS
The extracts below are direct quotations from the STUK annual report on nuclear safety (in Finnish, translations by the author).


DEFECTIVE CONSTRUCTION
*During the manufacturing of main components, some needs for repairs have arisen
(e.g. mistakes in welding and manufacturing).

*There were quality problems in the welds and shape of parts of the steel liner
welded together during the summer. Main reasons for the failure in welding
were, i.a. the fact that the diameters of the thin walled cylinders that were
welded together were a bit different from each other; welding conditions
changed during work and the welders made mistakes.

* Heat treatment of a flange of a steam generator failed and the flange had to
be changed for another one.

INCOMPETENT SUBCONTRACTORS
*Audits of manufacturers and suppliers still show, that a part of them has not
taken nuclear safety requirements into account in their work.

*Adequate supervision and guidance of subcontractors remains a challenge. This
was made evident i.a. by the failure in the welding of the steel liner of the
inner containment building. Supervision and guidance of subcontractors was
inadequate; coordination of work was lacking and that led to unfavourable
welding conditions, management was not aware of the nuclear safety requirements
that their quality specifications were based on and their supervision of work
was lacking.

*Observations on the working practices and quality management of the
organizations demonstrate that difficulties in Olkiluoto 3 quality management
continued. […] Subcontractors work was made more difficult by i.a. lacking
management of materials, documents and work methods.

TIME PRESSURE
*Time pressure in assembling components caused the manufacturer and supplier in
a few cases to set the date for inspection so early that the prerequirements
for inspection were not met and inspections had to be rescheduled.

*Manufacturing of diesel generators was started before the approval of their
design. A similar observation was made regarding the start of manufacturing of
some electric drives.

UNFINISHED DESIGN STILL CAUSING PROBLEMS
*When the design of some process and automation systems has proceeded slower
than general design and construction, changes have had to be made to existing
structures.

*There were still inadequacies in the design documents provided to STUK. Because
the inadequacies passed the inspections both by the vendor and the energy
company, there is still room for improvement in the quality control of both of
them.