Analysis of Safety Injection Fluid Mixing in the Downcomer and Cold Leg of Pressurized Water Reactors
Four PWR designs were analyzed to obtain detailed three dimensional temperature and velocity distributions in the downcomers for the various pressurized thermal shock conditions.
In U.S. PWRs the SI lines connected to the cold legs provide an opportunity for the SI water to mix with the loop flow in the cold leg before it reaches the downcomer. In addition, warm fluids flowing through vent valves or other passages from the upper plenum are sources for heating the fluid in the downcomer. Providing a lower plenum in the plant model is recommended to simulate the local buoyancy flow pattern when the loop flow is near zero. In some foreign plants, two additional SI lines inject directly into the vesel. The cold water from SI forms a jet in the downcomer and is heated up rapidly by entrainment effects.
KeywordsLoop Flow Pressurize Water Reactor Safety Injection Degree Model Vent Valve
Unable to display preview. Download preview PDF.
- 1.V.K. (Bindi) Chexal, T.U. Marston and B.K.H. Sun, “EPRI’s Efforts to Resolve Pressurized Thermal Shock Issue,” Journal of Nuclear Engineering International, May 1982.Google Scholar
- 2.H.M. Domanus, W.T. Sha, R.C. Schmitt, and V.L. Shah “COMMIX-1A: A Three Dimensional Transient Single Phase Component Computer Program for Thermal Hydraulic Analysis,” USNRC Report NUREG/CR-0785, September 1978.Google Scholar
- 3.J.H. McFadden, R.E. Narum, C.E. Peterson, C Noble, R.F. Farman, J.A. McClure, M.P. Paulsen, K.D. Richert, E.D. Hughes, G.C. Gose, L.V. Ellis, N.L. Ellis, K.R. Katsma, CG. Motloch, G.C. Rice, and D.S. Trott, “RETRAN-A Program for One Dimensional Transient Thermal Hydraulic Analysis of Complex Fluid Flow Systems,” EPRI NP-1850-CCM, Vols. 1-4, Computer Code Manual, May 1981.Google Scholar
- 4.C Peterson, B. Chexal, W. Layman, J. Chao, D. Prelevicz, and C Key “MSLB Analysis with RETRAN-02 for a Combustion Engineering PWR for Pressurized Thermal Shock Applications,” EPRI report in preparation.Google Scholar
- 5.“Analysis of a Hot Leg SBLOCA with Loop Stagnation in a 3-Loop PWR Plant,” an NSAC report to be published.Google Scholar
- 6.“GPU Nuclear Corporation Three Mile Island Unit 1 Reactor Vessel Pressurized Thermal Shock Evaluation,” June 1982.Google Scholar