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The relative axial expansions under irradiation of stacks of UO{sub 2} pellets in zircaloy sheaths

Abstract

An experiment was performed to measure the relative axial movement of UO{sub 2} fuel pellets inside a Zircaloy sheath. Although the results must be treated with some reservation, the inferences are that there is very little relative movement between the fuel and the sheath when the two are in firm pressure contact. Relative movement was in the range 0.075 {+-} 0.03 cm for a 30 cm fuel length, and was not greatly affected by the power output, profile of the pellet end-faces or the diametral clearance left between the fuel and the sheath on assembly. However in two elements that had thick sheaths to withstand the coolant pressure and that were assembled with large diametral clearances (2% of the diameter) the available axial clearance for relative fuel/ sheath movement (1%) was fully taken up. The thin sheathed elements showed residual axial expansions of up to 0.17 cm, indicating that the pellets move relative to the sheath only until frictional forces are sufficient for the sheath to grip the fuel; thereafter the sheath is extended. The measurements also indicate that sheath elongation is governed by the temperature at the contact points between adjacent pellets, eg. at the inner edge of a  More>>
Authors:
Publication Date:
Aug 15, 1962
Product Type:
Technical Report
Report Number:
AECL-1598; CRFD-1092; Exp-NRX-5603
Resource Relation:
Other Information: 17 refs., 8 tabs., 1 fig.
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; ELONGATION; FUEL CANS; FUEL PELLETS; IRRADIATION; URANIUM DIOXIDE; ZIRCALOY
OSTI ID:
22034844
Research Organizations:
Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)
Country of Origin:
Canada
Language:
English
Other Identifying Numbers:
TRN: CA1200131123850
Availability:
Available from INIS in electronic form
Submitting Site:
CANN
Size:
25 page(s)
Announcement Date:
Feb 01, 2013

Citation Formats

Notley, M. J.F. The relative axial expansions under irradiation of stacks of UO{sub 2} pellets in zircaloy sheaths. Canada: N. p., 1962. Web.
Notley, M. J.F. The relative axial expansions under irradiation of stacks of UO{sub 2} pellets in zircaloy sheaths. Canada.
Notley, M. J.F. 1962. "The relative axial expansions under irradiation of stacks of UO{sub 2} pellets in zircaloy sheaths." Canada.
@misc{etde_22034844,
title = {The relative axial expansions under irradiation of stacks of UO{sub 2} pellets in zircaloy sheaths}
author = {Notley, M. J.F.}
abstractNote = {An experiment was performed to measure the relative axial movement of UO{sub 2} fuel pellets inside a Zircaloy sheath. Although the results must be treated with some reservation, the inferences are that there is very little relative movement between the fuel and the sheath when the two are in firm pressure contact. Relative movement was in the range 0.075 {+-} 0.03 cm for a 30 cm fuel length, and was not greatly affected by the power output, profile of the pellet end-faces or the diametral clearance left between the fuel and the sheath on assembly. However in two elements that had thick sheaths to withstand the coolant pressure and that were assembled with large diametral clearances (2% of the diameter) the available axial clearance for relative fuel/ sheath movement (1%) was fully taken up. The thin sheathed elements showed residual axial expansions of up to 0.17 cm, indicating that the pellets move relative to the sheath only until frictional forces are sufficient for the sheath to grip the fuel; thereafter the sheath is extended. The measurements also indicate that sheath elongation is governed by the temperature at the contact points between adjacent pellets, eg. at the inner edge of a pellet shoulder, as long as that temperature is below approximately 1000{sup o}C. At higher temperatures, the UO{sub 2} is too plastic to exert sufficient force to strain the sheath. (author)}
place = {Canada}
year = {1962}
month = {Aug}
}