Nuclear Technology / Volume 155 / Number 3 / September 2006 / Pages 350-357
Technical Paper / Nuclear Plant Operations and Control / dx.doi.org/10.13182/NT06-A3767
This paper describes a new system for monitoring leaks in a steam generator. The new system extends the traditional 16N monitor to detect both the rate and the location of a leak. Because the transit time is different for radioactive 16N and 19O to travel from the reactor core via the hot bottom side, cold bottom side, or bend region of the U-tube in a steam generator to the gamma-ray detector, the new system uses the different transit times to identify the location of leaks. Specifically, the ratio S0 of 16N to 19O activities in the reactor core of a swimming pool reactor was calculated by combining the cross sections np(E) and n(E) with the neutron spectra n(E). The ratio S1 of 16N to 19O activities in the measurement room was also calculated and measured by the high-purity germanium and NaI(Tl) detectors. The result of the calculation agrees with the measurement within an acceptable range.