ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Explore membership for yourself or for your organization.
Conference Spotlight
2025 ANS Winter Conference & Expo
November 8–12, 2025
Washington, DC|Washington Hilton
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
Latest Magazine Issues
Oct 2025
Jul 2025
Latest Journal Issues
Nuclear Science and Engineering
November 2025
Nuclear Technology
Fusion Science and Technology
Latest News
Japan gets new U for enrichment as global power and fuel plans grow
President Trump is in Japan today, with a visit with new Prime Minister Sanae Takaichi on the agenda. Takaichi, who took office just last week as Japan’s first female prime minister, has already spoken in favor of nuclear energy and of accelerating the restart of Japan’s long-shuttered power reactors, as Reuters and others have reported. Much of the uranium to power those reactors will be enriched at Japan’s lone enrichment facility—part of Japan Nuclear Fuel Ltd.’s Rokkasho fuel complex—which accepted its first delivery of fresh uranium hexafluoride (UF₆) in 11 years earlier this month.
J. H. Brindley
Nuclear Science and Engineering | Volume 23 | Number 4 | December 1965 | Pages 313-328
Technical Paper | doi.org/10.13182/NSE65-A21067
Articles are hosted by Taylor and Francis Online.
Flat-plate fuel-element surface temperatures in the Organic Moderated Reactor Experiment were monitored by 0.005-in. (0.013-cm)-diam chromel-alumel thermocouple wires, spot-welded to the stainless-steel fuel-plate surface. The thermocouple assembly, being exposed to the coolant stream, is subject to thermal-loading errors; as a result, thermocouple-calibration tests were performed in a forced-convection heat-transfer loop with Santowax O-M flowing over an electrically heated test plate containing typical thermocouple specimens. The tests were conducted under the following simulated reactor conditions: coolant temperatures from 300 to 600°F (149 to 316°C), coolant velocities from 10 to 20 ft/sec (3.1 to 6.1 m/sec), and heat fluxes ranging from 0.50 × 105 to 1.6 × 105 Btu/(h ft2) (15.77 to 50.46 W/cm2). Test results demonstrate that at reactor operating conditions, 600 °F organic coolant flowing at 17.5 ft/sec (5.34 m/sec), the observed fuel-plate surface temperature is 700 °F (371 °C), while, in reality, the actual surface temperature is 750 °F (399 °C). The thermocouple thermal-loading errors were found to be a function of the coolant Reynolds and Prandtl numbers. Heat flux had no effect on the calibration. Excellent agreement was obtained between the experimental and predicted (Dittus-Boelter) heat-transfer coefficients for the organic coolant. Thermocouple-calibration factors for correction of observed surface temperatures over a wide range of operating conditions, are presented as a function of the organic-coolant heat-transfer coefficient on the fuel-plate surface. An electrical-analogue model of a thermocouple assembly on the surface of an OMRE fuel element was constructed to: a) verify experimental results; b) study the effect of a fouling film on surface-temperature measurements; and c) provide an inexpensive means of calibrating surface-attached thermocouples on fuel plates for future use. Prediction of thermal-loading errors associated with this type of surface-temperature measurement by the use of existing mathematical results is discussed. Good agreement was obtained between the electrical-analogue results, the analytical predictions, and the experimental data. Film formation on the fuel plate and the thermocouple wire was observed to reduce the thermocouple-calibration factor by as much as 45%.
