Abstract: The design, manufacture, and operation of thin-walled
pressure vessels must be based on maximum safe operating pressure
and an adequate factor of safety (FoS). This research paper first
reports experimental evaluation of longitudinal and hoops stresses
based on working pressure as well as maximum pressure; and then
includes a critical study of factor of safety (FoS) in the design of a
glass fiber pressure vessel. Experimental work involved the use of
measuring instruments and the readings from pressure gauges.
Design calculations involved the computations of design stress and
FoS; the latter was based on breaking strength of 55 MPa for the
glass fiber (pressure-vessel material). The experimentally determined
FoS value has been critically compared with the general FoS allowed
in the design of glass fiber pressure vessels.
Abstract: Fuel rod analysis program transient (FRAPTRAN)
code was used to study the fuel rod performance during a postulated
large break loss of coolant accident (LBLOCA) in Maanshan nuclear
power plant (NPP). Previous transient results from thermal hydraulic
code, TRACE, with the same LBLOCA scenario, were used as input
boundary conditions for FRAPTRAN. The simulation results showed
that the peak cladding temperatures and the fuel centerline
temperatures were all below the 10CFR50.46 LOCA criteria. In
addition, the maximum hoop stress was 18 MPa and the oxide
thickness was 0.003mm for the present simulation cases, which are all
within the safety operation ranges. The present study confirms that this
analysis method, the FRAPTRAN code combined with TRACE, is an
appropriate approach to predict the fuel integrity under LBLOCA with
operational ECCS.
Abstract: When the characteristic length of an elastic solid is
down to the nanometer level, its deformation behavior becomes size
dependent. Surface energy /surface stress have recently been applied
to explain such dependency. In this paper, the effect of
strain-independent surface stress on the deformation of an isotropic
elastic solid containing a nanosized elliptical hole is studied by the
finite element method. Two loading cases are considered, in the first
case, hoop stress along the rim of the elliptical hole induced by pure
surface stress is studied, in the second case, hoop stress around the
elliptical opening under combined remote tension and surface stress is
investigated. It has been shown that positive surface stress induces
compressive hoop stress along the hole, and negative surface stress has
opposite effect, maximum hoop stress occurs near the major semi-axes
of the ellipse. Under combined loading of remote tension and surface
stress, stress concentration around the hole can be either intensified or
weakened depending on the sign of the surface stress.