The Occurrence of Wear Marks on Fast Reactor Fuel Pin Cladding

Abstract

The surfaces of fuel pin cladding and spacer wire wound round it in the JOYO Mark-I and EBR-II test fuel were found to carry wear marks. Out-of-pile experiments indicated that simple hydraulic vibration could not constitute the cause of marking. Assuming the alternative factor of thermohydraulic vibration to be the cause, a model has been devised, applying which a method is proposed for estimating the ranges in which wear and contact marks can respectively be expected to occur. The two ranges are determined in terms of two parameters combining variables commonly used in practical fuel assembly design, and which are adopted as coordinates for a diagram in which data from actual fuel design are plotted. Data from actual reactor designs plotted in this diagram have proved to fall into two distinct domains respectively covering cases where wear and contact marks had been occasioned.

A multi-stage approach of simulating turbulence-induced vibrations in a wire-wrapped tube bundle for fretting wear prediction

“…In the literature [57], a need to research fretting for MYRRHA has been identified, but fatigue on the other hand is not expected [57,58]. Wear marks due to contact have been observed in real reactors with wire-wrapped fuel assemblies in hexagonal array [59]. The contact forces obtained from the simulations of present work can be used to calculate an estimate of the expected wear rate due to FIV, in order to meet this demand for fretting analysis.…”

Subchannel Analysis of Wire Wrapped SCWR Assembly

“…To obtain a small water volume fraction in core, tight lattices are necessary. Wire wrap spacers, an alternative to grid spacers, have been used extensively in LMFBR [3] and tight-lattice high-conversion cores [4], mainly due to their advantageous pressure drop and better mixing capability. As a consequence, the required coolant pumping power is decreased and the coolant temperature profile inside the fuel bundle is flattened which will obviously decrease the peak cladding temperature.…”