IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
Table 1 : Measured rupture lives of end plug welds with and without weld repairs (days)
Test results
The rupture lives measured
for the various test cases are
given in Table-1 and same have
been depicted in Fig.6, which
indicated that, the minimum
rupture time required (5.6 d)
are ensured even for the welds
with 4 repairs.
In view of a limited number of
tests that have been completed,
it is recommended to restrict
the weld repair to 2 at this
stage of manufacturing.
However, tests are being
continued to get more
confidence in accepting 3 or 4
repair welds.
Fig.5 Longitudinal cracks seen in the
fuel pins at the welding zone
Fig.6 Measured rupture lives of pins tested
II.7. Qualification of Back up Seals
To seal the annular gap between rotating and
stationary parts of the rotatable plug support
arrangement, elastomeric seals are provided.
This comprises of two numbers of inflatable seals
and one back-up seal. During reactor operation,
the annular gap is sealed by one of the inflatable
seals along with a back-up seal. Before starting
plug rotation, the second inflatable seal is
inflated and the back-up seal is disengaged and
kept in raised condition.
The back-up seal is a static seal with sealing
achieved by the compression of the seal. A
trapezoidal shape seal has been selected and to
reduce the compression load required to seal the
surfaces, special geometrical features are
included. The seal is fixed to a seal holder and to
apply required compression load uniformly over
the seal surface, load applying arrangement is
provided. The seal bridges two annular surfaces
at the top, one rotating and the other stationary.
22 PROTOTYPE FAST BREEDER REACTOR