Gas-fired electrical generating plant is operating increasingly in fast response mode to meet the variability of renewable generation. Fast power turn up and turn down is required to ensure grid frequency stability. Modern gas turbines operating in combined cycle mode can achieve fast response ramp rates typically in the region of 40 MWe/min (turbine, 2018), this places increased stress on thick walled steam turbine and boiler components, leading to steam leaks and premature failure.
Established methods by which these leaks are detected rely on pressure drop testing: for power plants operating in today’s fast response market conditions a pressure drop test is not possible. The first evidence of a tube leak is usually associated with a catastrophic failure of a tube necessitating an unplanned plant shutdown. To meet availability requirements, an alternative boiler leak detection system is called for.
The injection and detection of a short-lived radioactive tracer into the high pressure side of the boiler feed water circuit during operation would provide an indication of a leak in the low pressure circuit gases exiting the boiler gas stack.
This thesis examines if medical radionuclides injected into the boiler feedwater could be detected in the low pressure gas exhaust stream during the early propagation of a boiler tube leak site.