NuScale Power has announced that it has completed a "major test programme" to obtain heat flux data for nuclear fuel that will be used in its 45MW small modular reactor.

Testing began in September 2012 and was completed on 15 March 2013, NuScale said. The testing was carried out under "fully-prototypic conditions" in a specialized test rig at Stern Laboratories in Ontario, Canada.

A full-length, full-power, electrically-heated fuel assembly mock-up with spacer grids was tested for a wide range of natural circulation flow rates with both uniform and cosine shape power profiles.

The data, known as critical heat flux (CHF) data, is being used to define the limiting conditions for fuel performance and to validate NuScale’s safety analysis computer codes.

"The test results show that the NuScale fuel has a significant safety margin under natural circulation flow conditions," NuScale said.

Both United States and Canadian nuclear regulators witnessed the testing, which was conducted under strict quality assurance requirements of 10 CFR 50 Appendix B.