Single natural-circulation loop

Basu, D.N., Bhattacharyya, S., Das, P.K., 2014. A review of modem advances in analyses and applications of single-phase natural circulation loop in nuclear thermal hydrauUcs. Nuclear Engineering and Design 280, 326—348. 

CreveUng, H.F., Schoenhals, R.J., 1966. Steady Flow Characteristics of a Single-Phase Natural Circulation Loop. Technical Report No 15. Purdue Research Foundation. COO-1177-15. 

Misale, M., 2014. Overview on single-phase natural circulation loops. In Proceedings of the Intemational Conference on Advances in Mechanical and Automation Engineering — MAE 2014. http //dx.doi.org/10.15224/978-l-63248-022- 101. 

Misale, M., Ruflino, P., Frogheri, M., 2000. The influence of the wall thermal capacity and axial conduction over a single-phase natural circulation loop, 2-D uumerical study. InteraatioDal Journal of Heat and Mass Transfer 36, 533—539. 

PiUdiwal, D.S., Ambrosini, W., Forgione, N., Vijayan, P.K., Saha, D., Ferreri, J.C., 2007. Analysis of the unstable behavior of a single-phase natural circulation loop with one-dimensional and computational fluid-dynamic models. Annals of Nuclear Energy 34, 339—355. 

Rao, N.M., Maiti, B., Das, P.K., 2008. Steady state performance of a single phase natural circulation loop with end heat exchangers. Journal of Heat Transfer 130, 084506. 

Several scaling laws have already been proposed for the design of scaled loops simulating natural circulation phenomenon. Such scaling laws are available for both single- and two-phase natural circulation loops. 

Several experiments on single-phase natural circulation loops are reported in the literature. The loops studied can be categorised as Uniform Diameter Loops (UDLs) and Nonuniform Diameter Loops (NDLs). 

VUAYAN P.K, BADE, M.H, SAHA, D, SINHA, R.K., VENKAT RAJ, V., A generalized correlation for the steady state flow in single-phase natural circulation loops, BARC report, June 2000. 

Alstad, C.D., Isbin, H.S., Amundson, N.R., 1956. The Transient Behavior of Single-Phase Natural Circulation Water Loop Systems. Argonne National Lahoratoiy Report, ANL-5409. 

Ambrosini, W., Ferrai, J.C., 1997a. Numerical analysis of single-phase, natural circulation in a simple closed loop. In Proceedings of 11th Meeting on Reactor Physics and Thermal Hydraulics, Pocos de Caldas, MG, Brazil, August 18—22th 1997, pp. 676—681. 

Ambrosini, W., Ferreri, J.C., 1998. The effect of truncation error on the numerical prediction of linear stability boundaries in a natural circulation single-phase loop. Nuclear Engineering and Design 183, 53—76. 

A typical loop consists of a hot leg, a steam generator, a cold leg with the circulating pump and one accumulator tank connected to it. The hot leg is defined by a single volume connected to the vessel upper plenum and the inlet steam generator by flow paths. The cold leg has been divided into two volumes one including the pump suction and the other the pump and the rest of the circuit. This nodalization is required for a good representation of the pipe U-form in the pump suction, geometry which may affect natural circulation in the primary system. 

In our assessment [10], MELCOR correctly calculated the thermal/hydraulic phenomena observed during steady-state, single-phase liqiud natural circulation, as summarized in Table 3.1. MELCOR predicted the correct total flow rate and the flow split between two unequal loops without any ad hoc adjustment of the input. The code could reproduce the major ther-mal/hydraulic response characteristics in two-phase natural circulation, after a number of nonstandard input modelling modifications MELCOR could not reproduce the requisite physical phenomena with normal input models. The natural circulation mass flows predicted in these two cases are shown in Figure 3.1. 

For the single-phase case, the natural circulation flowrate is found by integration of the loop momentum equation and coupling this to the energy equation. Thus, the primary temperature increase is given by the standard result. 

There is a wide range of metals used in the construction of closed-loop circuits and the often considerable differences in the nature of the circulating water (ranging from deionized water to glycol mixtures to brine water). As a consequence, it is not possible to devise a single water treatment formulation that satisfies the requirements of all closed-loop circuits and their operators. 

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