Ex-Reactor Determination of Thermal Gap Conductance Between Uranium Dioxide and Zircaloy-4: Stage II: High Gas Pressure
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
An ex-reactor study of the thermal gap conductance between Uranium Dioxide (UO2) and Zircaloy-4 (Zr4) was performed under varying conditions of gas pressure (0.1 to 7 MPa); temperature (283 to 673 K); gas composition (He (100); Ar (100); He:Ar (51.79:48.21); and He:Xe (89.4:10.6)); and, average mean-plane separation distance Dmp = 5.9 {micro}m (light contact); and, Dmp = 23.1 {micro}m). In this report a description of the high pressure autoclave, specimen holder and associated apparatus is given together with experimental results. In conjunction with the experimental apparatus an assessment of determinant and indeterminant errors is made. In this report the predicted gap conductance based on the "ideal" expression for the gap conductance, Hg = Kgas/(d + g1 + g2) and assuming Dmp = d and g1 = g2, is compared to the Hg results and found not to be in agreement. Use of the ideal gap conductance expression under these conditions is seen to under-estimate the value of Hg results. A discussion of possible reasons for the differences between the observed and predicted behavior is made. In addition to experimental errors resulting from gaseous convection, a detailed examination of the ideal gap conductance expression reveals that the basic assumptions (upon which the ideal gap conductance expression is derived) are not valid for real surfaces in close proximity and/or contact.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE; USNRC
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 1076471
- Report Number(s):
- PNL--3232-Vol.2; NUREG/CR--0330
- Country of Publication:
- United States
- Language:
- English
Similar Records
Ex-reactor determination of thermal gap conductance between uranium dioxide and Zircaloy-4. Stage II: high gas pressure
Ex-reactor determination of thermal gap and contact conductance between uranium dioxide: zircaloy-4 interfaces. Stage I: low gas pressure. [PWR; BWR]
Preselectable integer quantum conductance of electrochemically fabricated silver point contacts
Conference
·
Fri May 01 00:00:00 EDT 1981
·
OSTI ID:6029459
Ex-reactor determination of thermal gap and contact conductance between uranium dioxide: zircaloy-4 interfaces. Stage I: low gas pressure. [PWR; BWR]
Technical Report
·
Sat Mar 31 23:00:00 EST 1979
·
OSTI ID:6268967
Preselectable integer quantum conductance of electrochemically fabricated silver point contacts
Journal Article
·
Mon Jul 28 00:00:00 EDT 2008
· Applied Physics Letters
·
OSTI ID:21124010