Advantages with low Nickel-release from Sandvik Alloy 690 steam generator tubes
Nickel-release from Alloy 690 Steam Generator Tubes is today becoming more and more of a concern for the growing fleet of Pressurized Water Reactors.This is because today longer fuel cycles are often adopted and the cores are also often run closer to sub-nucleate boiling.The longer fuel cycles makes more Nickel to be released and adhered to the fuel cladding tubes,resulting in that more activated products are created.More activated products mean problems with high radiation dose rates for workers when performing fuel replacement and during general maintenance at shut down periods.The sub-nucleate boiling makes the released Nickel to more easily adhere to the fuel cladding tubes 1.The present paper discusses and summarizes the problems that are occurring due to the fact that Nickel is released from Alloy 690 Steam Generator Tubes,i.e.problems with increased radiation fields,crud induced power shifts,reduced shut down margins,hot spots from crud and crud induced localized corrosion.The paper also discusses the general level of Nickel-release from Sandvik Steam Generator Tubes which has been shown by other investigators to be on the lower side when compared to other tube manufacturers 2.The reason for this lower release from Sandvik Steam Generator Tubes is however not fully understood and Sandvik is therefore focusing R&D-resources and test equipment into fully simulating primary water conditions and measure Nickel-release from Steam Generator Tubes.Initial results from tests performed show that the new test equipment is working good giving consistent and repetitive results.Initial test runs in the equipment also show that the Sandvik tubes passivate fast and that the Nickel-release level is very low.
Johan Frodigh Thomas O.J.Blomfeldt Erik K(o)nberg
AB Sandvik Materials Technology,Sweden
国际会议
沈阳
英文
129-140
2017-09-26（万方平台首次上网日期，不代表论文的发表时间）