Patent Number: 046997555
Section: claims

1. Ultrafiltration circuit for the primary cooling fluid of a pressurized-water nuclear reactor incorporating, inside a containment shell (1), a primary circuit (2) which communicates with the inner volume of the reactor vessel (3) containing a core consisting of fuel assemblies and in which the pressurized water constituting the primary fluid circulates, and at least one auxiliary circuit (8) taken off from the primary circuit (2) and comprising a discharge branch (10), on which are arranged means of cooling (12) and depressurizing (13) the primary fluid extracted by means of the auxiliary circuit (8) and which passes through the wall (1) of the containment shell, and a charge branch (11) for returning the fluid into the primary circuit (2) and likewise passing through the wall (1) of the containment, and, outside the containment, means (17, 18, 19, 20) of purifying and treating the cooled and depressurized fluid, wherein the containment shell contains (a) a first loop (27) taken off from the discharge branch (10) of the auxiliary circuit (8) and incorporating a pipe (29) for extracting and conveying fluid at its operating pressure and temperature into a first ultrafiltration device (30) located in the first loop (27), a pipe (31) for discharging filtrate at the outlet of the ultrafiltration device (30) and for returning this filtrate into the discharge branch (10) downstream of the point (33) where fluid is extracted by means of the extraction pipe (29), a valve (32) being inserted in the discharge branch (10) between the two pipes (29, 31), and a concentrate discharge pipe (39) which passes through the wall (1) of the containment and on which are arranged, inside the containment, means (40, 41) of cooling and depressurizing the concentrate before it is introduced into the discharge branch (10) of the auxiliary circuit (8) downstream of the cooling and depressurizing means (12, 13) arranged on this discharge branch (10); and  (b) a second loop (28) taken off from the charge branch (11) of the auxiliary circuit (8) and incorporating a pipe (49) for extracting and conveying fluid at its operating temperature and pressure into a second ultrafiltration device (50) located in the second loop (28), a pipe (51) for discharging the filtrate at the outlet of the ultrafiltration device (50) and for returning this filtrate into the charge branch (11) downstream of the extraction point (54), a valve (52) being inserted between these two pipes (49, 51), and a concentrate discharge pipe (58) connected to the discharge branch (10) of the auxiliary circuit (8), inside the containment, upstream of the cooling and depressurizing means (12, 13) arranged on this branch (10). 2. Ultrafiltration circuit according to claim 1, wherein the discharge branch (10) of the auxiliary circuit (8) incorporates a part of the primary circuit (2) which includes a primary pump (7), and wherein the first loop (27) of the ultrafiltration circuit is taken off from the primary pump (7). 3. Ultrafiltration circuit according to claim 1, comprising a concentrate purification filter (60) arranged on the discharge pipe (38) outside the containment shell (1). 4. Ultrafiltration circuit according to claim 3, wherein the filter (60) is a filter with mixed-bed ion-exchanger resins. 5. Ultrafiltration circuit according to claim 1, wherein the concentrate retained by the ultrafiltration device (30, 50) is made to circulate by means of a circulating pump (36, 56) in a circuit (35, 55) incorporating part of the extraction and supply pipe (29, 49). 6. Ultrafiltration circuit according to claim 5, wherein the filtrate discharge pipe (38, 58) forms a link to the concentrate circulation circuit (35, 55), and a regulating device (37, 57) makes it possible to extract some of the concentrate circulating in the circuit (35, 55) via the discharge pipe (38, 58). 7. Ultrafiltration circuit according to claim 5, wherein the filtrate discharge pipe (38, 58) forms a link to the concentrate circulation circuit (35, 55), and an adjustable three-way valve makes it possible to extract some of the concentrate circulating in the circuit (35, 55) via the discharge pipe (38, 58).