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

technology programme (cont’d.)
progress report
2010
077
PACTITER model are the same as the real ones; inlet
coolant temperature of each injector component is 35°C.
The NBIs PHTS ACP inventory calculations were carried
out for a 7–week operation scenario split in 23 steps
alternating the various operational phases gathered in
table 3.I. Each operation day includes 14.4 h of mean up (or
operation) time (MUT) and 9.6 h of not–scheduled mean
down time (MDTNS). Every 11 operation days, 3 routine
maintenance days (MDTs) are foreseen.
The most important parameter governing the build–up of
the ACPs inventory is the Cu and Cu alloy corrosion rate.
The influence of chemical volume control system (CVCS)
flow rate and filter efficiency is relatively scarce, as no
appreciable reduction in the ACP mass was assessed by
variation of those parameters. The possibility to separate the
LV–active correction and compensation coils (ACCCs) from
the NBIs PHTS by a dedicated cooling loop was also
investigated. The impact of this choice would be remarkable
in terms of ACP mass reduction (factor ∼3.7; see fig. 3.45,
Run–8). That is explained by the large wet surface of
ACCCs (3798 m 2 which is ∼50% of the total loop wet
surface) made of Cu which is affected by a larger corrosion
and release rates as compared to stainless steel regions.
Another way to reduce the ACCCs wet surface of a factor 2
is by doubling the pancake piping diameter from 8 to
16 mm. That would cause a drop of ∼40% of the ACP mass
(see fig. 3.46, Run–5) [3.18].
One might argue that splitting the NBIs PHTS loop in two
parts would not reduce the overall ACP mass which would
be transferred to the dedicated ACCCs cooling loop. The
actual advantage is the reduction of ACPs radioactive
inventory (see fig. 3.46). The larger ACP mass inventory of
ACCCs would be contained in a dedicated loop, which will
be much less activated, considering their position far from
the plasma and from to the neutrons line of sight. On the
contrary, if contained in the NBIs PHTS this large ACP
inventory would be activated at higher level when
transported to loop’s regions where the neutron flux is larger.
Table 3.I – Main operation scenario data
Operational
phase
Time
(d)
H 2
(ppm)
T mh
*)
(°C)
Idle (MDT S ) 6.9 0.06 35
Conditioning
(MDT S )
3.6 2 55
Injecting (MUT) 5.15 2 61
Decay/dwell
(MUT)
Maintemance
(MDT NS )
18.0 0.06 45
15.35 0.06 35
*) T mh = means temperature of the primary fluid in the
under flux region
(g)
8000
4000
0
0
Run-3 ACCCs wet surface=3798 m 2
Run-5 ACCCs wet surface=1899 m 2
Run-8 ACCCs wet surface=0 m 2
20 40
Time (days)
Figure 3.45 – Impact of the ACCCs Ws on the ACP
inventory (Run-3: full wet surface, Run–5: ½ wet
surface, Run–8: no ACCCs)
Surface activity (GBq)
2000
1000
Run-3
Run-8
0
0 20 40
Time (days)
Figure 3.46 – ACP surface activity in NBI–PHTS
with ACCCs (Run–3) and without ACCCs (Run–8)
Safety analyses by hazard and operability studies
Several hazard and operability (HAZOP) studies have been performed for the ITER detritiation systems under
the frame of different ITER and F4E contracts/grant:
• Pre–conceptual design of the high tritiated water processing system to detritiate highly tritiated water
produced during normal and also abnormal situations of ITER operations (ITER
Contract/CT/09/4300000087) [3.19].
• Conceptual design of the tokamak complex detritiation system aimed at detritiating the gas effluents from
tokamak complex (ITER Contract/CT/09/4300000098) [3.20].
• Conceptual design of the water detritiation system aimed at storing and detritiating the aqueous effluents
produced by the detritiation system and from other sources – F4E Grant –2010–GRT–045 (PNS–VPT)
[3.21].
The HAZOP studies have been performed according to the “ITER Guide to Performing Hazard and