A ¹⁶N/¹⁹O Monitor for Leak Detection in a Steam Generator

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.