Prime pagine RA2010FUS:Copia di Layout 1 - ENEA - Fusione

058
progress report
2010
development and manufacturing of plasma facing compontens
(PFCs) for the ITER tokamak and to the qualification of the
manufacturing technologies for the ITER divertor procurement.
Figure 3.2 – Plane CFC–Cu joint sample
Amplitude
40
30
20
10
0 0 0 20
C-scan 0
C-scan 1
C-scan
REPORT
100
0
-100
Nome del file
30 40 50 60
13.39 17.39 22.00
-19.28 43.75 0.00
120
80
40
0
DX mm
32.67
DY mm
26.36
TXT
OK
D:\Lavoro\ULTRASUONI\CAMPIONE01ULTRAN\ultime provecd
plane15.rf1
One of the main issues in the manufacturing of the plasma facing
units is the reliability of the non destructive controls that are
necessarily performed during the manufacturing process. ENEA has
developed a suitable ultrasonic technique (UT) for the control of all
the joining interfaces of the ITER divertor IVT plasma facing units,
but the defect detection capability of the method has to be proved for
both metal to metal and metal to CFC joints, since both types of
joints are present. Within this activity, the UT results coming from
the investigation being performed during the manufacturing, but also
after the thermal fatigue testing (up to 20 MW/m 2 ) of mock–ups
manufactured in ENEA labs by using the HRP technology were
studied and compared with the evidences coming from the final
destructive examination in order to qualify the method. Regarding
the Cu/CFC joint, the effectiveness of the ultrasonic test has been
deeply studied due to the high acoustic attenuation of CFC to
ultrasonic waves. For these purpose an ‘ad hoc’ plane Cu/CFC joint
sample, that reproduces the actual annular joint interfaces, was
manufactured. This plane sample has the advantage of being easily
tested by probes with different geometry and ultrasonic
characteristics. UT testing results were compared with x–ray and
Eddy current of the same sample.
The results confirmed that the evidences detected by UT can be
easily correlated to lack of adhesion of the copper to CFC; in fact,
the position of the defective zones coincides with the points where
the brazing alloy deposition did not succeed.
Figure 3.2 shows the CFC–Cu sample being used for the testing and
figure 3.3 compares the images obtained by the different techniques:
UT, x–ray, Eddy current.
C-scan
Height
0
10
20
30
0 50 100 150
Figure 3.3 – Images obtained by UT,
x–ray, and Eddy current
Analysis of the ITER divertor cassettes
ENEA completed the activities related to the performing of a new set
of 3D electromagnetic (EM) and mechanical analyses of the revised
design of the ITER divertor cassettes to the purpose of checking the
fulfillment of the requirements and better assessing the merits of
each envisaged alternative during several off–normal events,
including category II and III events. These activities, in the frame of
the European Fusion Development Agreement (EFDA) Contract 07–
1702/1596 (TW6–TVD–DIAGAN) [3.1], were performed with the
support of L.T. Calcoli, an Italian company specialized in
electromagnetic and structural finite element analysis.
The Divertor is one of the most challenging components of the ITER machine: it is designed to sustain the
heat load and reduce the impurity in the plasma: it consists of the PFCs and a massive structure called the
cassette body (CB) (fig. 3.4). The PFCs are actively cooled thermal shields required to sustain the heat and
particle fluxes during normal and transient operations as well as during disruption events. The CB is needed
for supporting the PFCs, routing the water coolant into them and providing neutron shielding: it is mounted
onto the vacuum vessel’s (VV) inboard and outboard rails via a mechanical locking system.
The performed 3D EM numerical analysis allowed the EM loads to be calculated, including integral forces
and moments on the PFCs, CBs and components (pipes, manifolds and multilinks in figure 3.5) due to halo
and Eddy currents by taking into account both the thermal and current quench. The EM loads thus obtained
were then transferred for the corresponding dynamic mechanical analysis that allowed the stresses and