Method for identifying the unit causing a raw water leak in a condenser of a thermal power plant

Abstract

The present invention relates to a method for identifying the unit causing a raw water leak in a condenser of a thermal power plant consisting of n units.

Claims

1. A method for identifying the unit causing a raw water leak in a condenser of a thermal power plant consisting of n units, wherein n is an integer comprised between 2 and 15, wherein each of the n units is equipped with a cartridge intended to contain an ion-exchange resin in a volume comprised between 50 and 150 mL, comprising the following steps: a) for each of the n units, purifying the ion-exchange resin to be placed in the cartridge; b) for each of the n units, placing the purified ion-exchange resin obtained from step a) in the cartridge; c) for each of the n units, passing a volume of condensate comprised between 500 and 1500 L, into the cartridge containing the purified ion-exchange resin put in place in step b); d) for each of the n units, collecting the ion-exchange resin obtained at the end of step c); e) for each of the n units, regenerating the ion-exchange resin collected in step d) by elution with an aqueous regeneration solution; f) for each of the n units, collecting the eluate obtained at the end of step e) followed by determining the nature of the ionic species present in the eluate and the amount of each ionic species present in said eluate; and g) for each of the ionic species identified in step f), comparing the amounts of the ionic species determined in each of the n eluates.

2. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 1, wherein the ion-exchange resin has a total exchange capacity greater than 1.0 eq/L.

3. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 1, wherein the raw water contains Na.sup.+ and/or Ca.sup.2+ ions, and the ion-exchange resin is a cationic resin.

4. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 3, wherein step a) is carried out by elution of the cationic resin with a volume of acidic solution at least 2 times the volume of resin.

5. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 4, wherein the acidic solution is a strong acidic solution which has a concentration of Na.sup.+ and Ca.sup.2+ ions of less than 1 ppb.

6. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 3, wherein step e) is carried out by elution of the cationic resin with a volume of aqueous regeneration solution at least 2 times the volume of resin.

7. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 6, wherein the aqueous regeneration solution is a strong acidic solution which has a concentration of Na.sup.+ and Ca.sup.2+ ions of less than 1 ppb.

8. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 1, wherein the raw water contains Cl.sup.− ions, and the ion-exchange resin is an anionic resin.

9. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 1, wherein n is an integer comprised between 3 and 8.

10. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 1, wherein the cartridge is intended to contain an ion-exchange resin in a volume comprised between 80 and 120 mL.

11. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 1, wherein in step c), the passed volume of condensate is comprised between 800 and 1 200 L.

12. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 1, wherein the ion-exchange resin has a total exchange capacity greater than 1.5 eq/L.

13. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 3, wherein step a) is carried out by elution of the cationic resin with a volume of acidic solution at least 4 times the volume of resin.

14. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 3, wherein step a) is carried out by elution of the cationic resin with a volume of acidic solution at least 5 times the volume of resin.

15. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 4, wherein the acidic solution is a strong acidic solution which has a concentration of Na.sup.+ and Ca.sup.2+ ions of less than 0.5 ppb.

16. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 4, wherein the acidic solution is a strong acidic solution which has a concentration of Na.sup.+ and Ca.sup.2+ ions of less than 0.2 ppb.

17. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 3, wherein step e) is carried out by elution of the cationic resin with a volume of aqueous regeneration solution at least 4 times the volume of resin.

18. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 3, wherein step e) is carried out by elution of the cationic resin with a volume of aqueous regeneration solution at least 5 times the volume of resin.

19. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 6, wherein the aqueous regeneration solution is a strong acidic solution which has a concentration of Na.sup.+ and Ca.sup.2+ ions of less than 0.5 ppb.

20. The method for identifying the unit causing a raw water leak in a condenser of a thermal power plant according to claim 6, wherein the aqueous regeneration solution is a strong acidic solution which has a concentration of Na.sup.+ and Ca.sup.2+ ions of less than 0.2 ppb.

Description

FIGURES

(1) FIG. 1: simplified representation of a pressurized-water nuclear power plant.

(2) FIG. 2: schematic representation of a steam generator.

(3) FIG. 3: schematic representation of an elementary condenser unit, associated with its detection system consisting of a cation-exchange resin and a conductivity meter.

(4) FIG. 4: Schematic representation of the saturation of a cation-exchange resin with Na.sup.+ ions.

(5) FIG. 5: Schematic representation of the regeneration of a cation-exchange resin.

(6) FIG. 6: Schematic representation of the steps implemented in the example described below.

(7) FIGS. 7a and 7b: Concentrations of Ca.sup.2+ ions determined in the different units of a condenser in the examples described below, without carrying out a resin purification step (7b) or by carrying out the method according to the invention (7a).

EXAMPLES

(8) Implementation of the Method According to the Invention:

(9) The protocol described below was implemented on a nuclear power plant condenser consisting of 7 units, the cooling circuit of which is fed by raw river water containing Na.sup.+ and Ca.sup.2+ ions. The different steps are shown in FIG. 6.

(10) The cationic resin used is amberlite IRN97 H.

(11) A resin purification operation is carried out by pouring 500 mL of a hydrochloric acidic solution over 100 mL of resin. The solution used is a 15% dilution of Suprapur® hydrochloric acid marketed by Merck, the dilution being carried out with demineralized water having an Na.sup.+ and Ca.sup.2+ concentration of less than 1 ppb.

(12) A cartridge containing 100 mL of previously purified cationic resin is placed on each condenser unit.

(13) Water from the secondary circuit (a) is passed over the cartridge containing 100 mL of purified cationic resin, the cations contained in the water are retained on the resin (b). Once sufficient condensate has passed over the resin (about 1 m.sup.3), the resin is recovered and transferred (c) to a laboratory glass column (d). The resin in the glass column is then eluted (acid is circulated over it) by a concentrated acidic solution containing H.sup.+ ions (e). The H.sup.+ ions will replace the fixed cations (g and h) on the resin. The cations thus removed (f) will be recovered and measured by a specific apparatus (i).

(14) The elution operation consists of pouring 500 mL or more of acid over 100 mL of resin. The acidic solution used is the same as that used for the purification operation. The acid flows through the resin at a rate of one to two drops per second. The eluate is recovered from the resin in 100 mL fractions. Calcium is dosed onto each fraction collected by atomic absorption spectrometry.

(15) These cations come from the known volume of condensate with which the resin was eluted. It is therefore possible to determine the concentration of Ca.sup.2+ ions present in the condensate for each unit.

(16) The results obtained are shown in FIG. 7a.

(17) Comparative Example

(18) The same protocol is reproduced, without purifying the cationic resin. The results obtained are shown in FIG. 7b.