Removing cesium radionuclides from sodium-potassium coolant

Translated from Atomnaya Énergiya, Vol. 66, No. 1., pp. 22–24, January, 1989.     

Analysis of performance of fuel elements of the BOR-60 reactor with vibrocompacted uranium-plutonium oxide fuel

Translated from Atomnaya Énergiya, Vol. 66, No. 5, pp. 299–302, May 1989.     

Long-term recovery of pressurized water reactors following a large break loss-of-coolant accident

The U.S. Nuclear Regulatory Commission recently identified a possible safety concern for pressurized water reactors. Following the reflood phase of a large break loss-of-coolant accident, long-term cooling of the reactor core may not be ensured. Specifically, the concern is that, for a pump discharge cold leg break, the loop seals in the reactor coolant pump suction piping will refill with liquid and the post-reflood steam production may depress the liquid levels in the downflow sides of the loop seals. A loop seal depression would cause a corresponding depression of the core liquid levels and possibly a fuel rod heatup in the upper core region. This paper is intended as an introduction of the safety issue that: (1) describes the important aspects of the problem, (2) provides an initial analysis of the consequences, and (3) discusses ongoing work in this area. Because the elevation of the loop seals is near the mid-core elevation in plants of Westinghouse design, the concern is greatest for those plants. There is less concern for most plants of Combustion Engineering design, and likely no concern for plants of Babcock and Wilcox design. This issue was addressed by employing both steady-state and transient systems analysis approaches. Two approaches were used because of uncertainties regarding actual reactor coolant system behavior during the post-reflood period. The steady-state approach involved the development and application of a simple computer program to investigate reactor coolant system behavior assuming quiescent post-reflood conditions. The transient systems approach involved investigating this behavior using the RELAP5/MOD2 computer code and a comprehensive RELAP5 model of a Westinghouse pressurized water reactor. The steady-state analysis indicated only a moderate fuel rod heatup is possible. The transient systems analysis indicated boiling and condensation-induced flow oscillations are sufficient to prevent fuel rod heatup. Analysis uncertainties are discussed.     

Heat treatment of drill pipe of strength group D

Taganrog Metallurgical Plant. Translated form Metallurg, No. 11, p. 34, November, 1989.     

General purpose centrifugal compressor 32VTs-100/9

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 4, pp. 14–15, April, 1989.     

Long distance fiber-optic transmission of C-band microwave signals to and from a satellite antenna

We demonstrate here the use of high-speed semiconductor lasers and detectors with low loss optical fiber for the transmission of the 500-MHz C-band microwave signal spectrum to and from a satellite antenna. The optical system has low attenuation and large band, width, so the microwave signals can be transmitted directly at the microwave frequency (4 or 6 GHz) over 20 km of fiber without regeneration or qualization. The optical system introduces ≈ 1 dB or less of degradation for both low spectral density QPSK signals and high spectral density FM video signals present in typical satellite transmission systems. For the video signals, the signal to noise after AM conversion was reduced from 56 to 55 dB. The microwave drive level to the laser must be significantly larger (typically > -10 dBm) than the intensity noise of the laser, yet small enough (typically < 10 dBm) to reduce the intermodulation distortion signals to an acceptable level. The laser bias current must be several times threshold so that the resonance frequency is beyond the frequency band of interest (4-6 GHz in this case). A flat modulation response is then obtained, and the intensity noise and intermodulation levels are low.     

Subkilohertz fluctuations and mode hopping in high-powergrating-stabilized 980-nm pumps

The behavior of fiber Bragg grating (FBG)-stabilized 980-nm pump lasers is experimentally and theoretically investigated. The subkilohertz noise in the emitted power is related to the coexistence and oscillation between coherence collapsed state and narrow linewidth single-mode (SM) operation. These findings are theoretically discussed by using a multimode time-domain model that accounts for spatial harmonics and includes nonlinear gain. One additional result is an indication that kinks in the L-I curve can be explained by nonlinear mode competition