JAEA-Review-2010-065.pdf:15.99MB - 日本原子力研究開発機構

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Touch-Down Test of Magnetic Bearing Type Centrifugal
Contactor with Irradiated Touch-Down Bearing
H. Ogino, K. Fujisaku and H. Hirano
Nuclear Cycle Engineering Department, NFCEL, JAEA
The centrifugal contactor has excellent phase separation
and a smaller hold-up volume than any other contactor type
such as mixer-settler and pulsed column. These
characteristics lead to “rapid start-up and shut-down”,
“compact design” and “less solvent degradation”.
Therefore, the centrifugal contactor is said to be
advantageous for reprocessing a fast breeder fuel of high
burn-up and high Pu-enrichment 1) , and study and
development have been progressed since the 1960s.
In JAEA, the rolling bearing type centrifugal contactor
with anti-corrosion design (include air purge system,
ceramic-bearing and others) has been developed and has
achieved to 5,000 hours of operation without significant
troubles. However, the grease becomes deteriorated by
acid mist, temperature and other environmental factors, and
2)
that also affects the service life . To provide a possible
resolution to this technical issue, we have developed the
centrifugal contactor of non-contact journaled construction
3)
using magnetic bearings without grease . A magnetic
bearing has the construction in which the attractive force of
electromagnets is exerted to levitate a rotor without
mechanical contact. Figure 1 shows the overview of
irradiated magnetic bearing type centrifugal contactors and
the structure of magnetic bearing.
We carried out the gamma-ray irradiation test of
centrifugal contactor with magnetic bearing system to
estimate the radiation resistance in 2008. The equipments
stopped several times under irradiation, and were not finally
reactivated of two different factors, one was abrasion of the
touch-down bearing and adhesion to the main shaft (shown
in Fig. 2), the other was a trouble of IC. Accumulated dose
of the equipments was 3.7- 4.7 × 10 8 R. Therefore, the
present work is intended to investigate whether the cause of
the stop with the touch-down bearing is an influence of
gamma-ray irradiation.
Motor
Rotor
Fig. 1 Irradiated magnetic bearing type centrifugal
contactors and structure of magnetic bearing.
JAEA-Review 2010-065
Thrust
magnetic bearing
Upper
touch-down
bearing
Radial
magnetic bearing
Lower
touch-down
bearing
Main shaft
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The touch-down test were continuously carried out 6 runs
(1run: 5 times touch-down) using the magnetic bearing type
centrifugal contactor to which irradiated the lower
touch-down bearing (a slide bearing formed of polyimide
resin) was put in. So we observed the touch-down bearing,
the main shaft, etc and monitored the control situation of
magnetic-bearing after the touch-down test. Gamma-ray
was irradiated to the lower touch-down bearing up to about
10 9 R at a rate of 17.3 kGy/h at room temperature. Figure
3 shows the observation result after the touch-down test
(6 runs, 1 × 10 9 R). As shown in Fig. 3, neither abrasion of
the touch-down bearing nor adhesion to the main shaft was
observed. Moreover, the problem did not occur to control
situation of the magnetic-bearing. Based on these results,
we concluded that polyimide resin was a material which
could be used under these system requirements. In the
future, we will carry out gamma-ray irradiation test of
improvement equipment which reflected these results again.
Main shaft and adhesion material
Fig. 2 Main shaft of No.1 equipment after the irradiation
test (4.7 × 10 8 R).
Lower touch-down bearing Main shaft
Fig. 3 Main shaft and lower touchdown bearing after the
touch-down test (6 runs, 10 9 R).
References
1) G. J. Bernstein et al., ANL-7969 (1973).
2) T. Washiya et al., Proc. Global 2005 (2005).
3) N. Okamura et al., Proc. Global 2007(2007).