RD&D-Programme 2004 - SKB

Important events
In the project
2004 2005 2006 2007 2008 2009
Application
deep repository
Encapsulation plant
Application
Permit
Safety assessments
SR-Can
SR-Site
Supporting material for safety
assessment, fabrication and
sealing
Sealing methods
Executed
Fabrication methods
Methodology
Methodology
Executed
NDT
NDT
NDT
Supporting material for safety
assessment NDT
Insert
Reliability study
NDT welding
Reliability study
NDT fabrication
Methodology/plan
established
Probabilistic
strength analysis
finished
Reliability
NDT fabrication
executed
Figure 7-1. Timetables for compiling supporting material for the various safety assessments.
7.2 Qualification of NDT methods
The canisters with spent nuclear fuel will undergo NDT by means of e.g. radiography and
ultrasonics before being emplaced in the repository. Like the fabrication and sealing methods,
the NDT methods planned to be used will also undergo qualification.
Conclusions in RD&D 2001 and its review
Two milestones can be distinguished in qualification. The first will be reached when SKB plans
to apply for a permit to build an encapsulation plant. At this point, qualification will be focused
on so-called technical justification. What technical justification entails is laid down in ENIQ
(European Network for Inspection Qualification) Recommended Practice 2 /7-2/. SKB intends
to apply this recommendation in the documentation of its NDT methods. The second milestone
will be reached when the encapsulation plant is commissioned. Then SKB intends to qualify the
NDT methods based on ENIQ Recommended Practice 4 /7-3/.
SKI recommends that SKB more clearly describe who is to carry out the qualification of nondestructive
testing and what the infrastructure for qualifications should look like. SKI believes
that SKB underestimates the time required for qualification and that the results of qualification
can, at a late stage, influence the design of the encapsulation plant, for example if an NDT
method does not have the desired result.
Furthermore, the Inspectorate points out that the qualification methodology described in ENIQ’s
document must be adapted for the nondestructive testing of canisters, since it has actually
been developed for the recurrent testing of mechanical devices in nuclear power plants. The
development of the methodology should take place towards clearly defined qualification goals.
A necessary condition for qualification is knowledge of possible defects as well as acceptance
criteria. The work on acceptance criteria must be given high priority.
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