Nuclear power plant and method for operating a nuclear power plant

Patent metadata

Field	Value
Publication number	US-11170902-B2
Application number	US-201615779287-A
Country	US
Kind code	B2
Filing date	Nov 22, 2016
Priority date	Nov 30, 2015
Publication date	Nov 9, 2021
Grant date	Nov 9, 2021

Abstract

A nuclear power plant comprising a primary coolant circuit, a steam-water circuit separated from the primary coolant circuit and a steam generator connected to the primary coolant circuit and the steam-water circuit to transfer heat from the primary coolant circuit into the steam-water circuit has at least one dosing point in the steam-water circuit to inject a reducing agent into the steam-water circuit, wherein the reducing agent is an organic compound consisting of carbon, hydrogen and oxygen. Furthermore, a method for operating said nuclear power plant and the use of the method for downtime preservation of the secondary side of a steam generator of a nuclear power plant are provided.

First claim

The invention claimed is:

1. A nuclear power plant comprising a primary coolant circuit, a steam-water circuit separated from the primary coolant circuit and a steam generator connected to the primary coolant circuit and the steam-water circuit to transfer heat from the primary coolant circuit into the steam-water circuit, wherein the steam-water circuit has:
at least one dosing point to introduce a reducing agent that is an organic compound consisting of carbon, hydrogen and oxygen and set a predetermined oxygen concentration in the steam-water circuit and reducing conditions within the steam generator;
at least one potential sensor located in the steam generator and configured to measure a redox potential of water in the steam-water circuit, and
at least one TOC flowmeter configured to measure the concentration of the reducing agent in the steam-water circuit.

2. The nuclear power plant according to claim 1 , wherein the reducing agent acts as an oxygen scavenger when exposed to gamma radiation.

3. The nuclear power plant according to claim 1 , wherein the reducing agent is selected from the group consisting of C1-C6 alcohols, aldehydes, ketones and mixtures thereof.

4. The nuclear power plant according to claim 3 , wherein the reducing agent is a C1-C6 alcohol.

5. The nuclear power plant according to claim 4 , wherein the reducing agent is methanol.

6. The nuclear power plant according to claim 1 , wherein the steam-water circuit has a condenser and a main condensate pump, and the dosing point is located between the condenser and the main condensate pump.

7. The nuclear power plant according to claim 1 , wherein the steam-water circuit has a feed water container, and the dosing point is located downstream from the feed water container.

8. A method for operating a nuclear power plant comprising a primary coolant circuit, a steam-water circuit separated from the primary coolant circuit and a steam generator connected to the primary coolant circuit and the steam-water circuit to transfer heat from the primary coolant circuit into the steam water circuit, the method comprising introducing an organic reducing agent consisting of carbon, hydrogen and oxygen into the steam-water circuit by means of a dosing device,
measuring a redox potential of water in the steam-water circuit with at least one potential sensor located in the steam generator,
measuring a concentration of the reducing agent in the water of the steam-water circuit with at least one TOC flowmeter and;
adjusting the concentration of the reducing agent with the dosing device based on the measured redox potential and reducing agent concentration such that a predetermined oxygen concentration is set in the steam-water circuit and reducing conditions are set within the steam generator.

9. The method according to claim 8 , further comprising setting a pH of greater than 7 in the steam-water circuit.

10. The method according to claim 8 , wherein the concentration of the reducing agent is continuously measured.

11. The method according to claim 8 , wherein the steam-water circuit comprises a main condensate portion leading a main condensate from a condenser to a feed water container, where the main condensate and water from a water separator are collected and maintained for supply as feed water and a feed water portion leading from the feed water container to a feed water supply line at the steam generator, the method further comprising analyzing and controlling the oxygen content in the main condensate and/or the feed water with the concentration of the reducing agent.

12. The method according to claim 8 , wherein the steam generator has a circulation space in which circulating water circulates to absorb heat from the primary coolant circuit, with the concentration of the reducing agent in the circulating water being in a range from 10E-7 mol/kg to 10E-3 mol/kg.

13. The method according to claim 12 , wherein the concentration of the reducing agent in the circulating water is in the range of 3×10E-7 to 3×10E-4 mol/kg.

14. The method according to claim 8 , wherein the steam-water circuit has a feed water portion comprising a feed water supply line, and that the steam generator comprises a circulation space in which circulating water circulates to absorb heat from the primary coolant circuit, and wherein the concentration of the reducing agent is determined in the feed water and/or in the circulating water by means of the TOC flowmeters.

15. The method according to claim 8 , wherein the steam generator further comprises a circulation space in which circulating water circulates to absorb heat from the primary coolant circuit, and wherein the redox and/or corrosion potential is measured in the circulating water by means of the potential sensor.

16. The method according to claim 8 , wherein the steam generator further comprises a circulation space in which circulating water circulates to absorb heat from the primary coolant circuit, and wherein the redox potential in the circulating water is measured continuously and used as a control parameter for adjusting the concentration of the reducing agent.

17. The method according to claim 8 , wherein the steam generator comprises a circulation space in which circulating water circulates to absorb heat from the primary coolant circuit, and wherein the redox and/or corrosion potential in the steam-water circuit is/are measured to adjust oxidizing conditions in the steam-water circuit and wherein, at the same time, the redox and/or corrosion potential in the circulating water is/are measured to adjust the reducing conditions of the circulating water.

18. The method according to claim 8 , wherein the steam generator further comprises a circulation space in which circulating water circulates to absorb heat from the primary coolant circuit and wherein the concentration of the reducing agent in the circulating water is maintained in a range from 5×10E-6 mol/kg to 5×10E-2 mol/kg.

19. The method according to claim 8 , wherein the predetermined oxygen concentration is not more than 0.1 mg/kg.

Assignees

• Framatome Gmbh

Inventors

• Stellwag Bernhard
• Fandrich Jörg

Classifications

• G21C17/0225 Primary

  Chemical surface treatment, e.g. corrosion (corrosion prevention in presence of water from scale removal or by modification of the properties of the liquid C02F5/00; inhibiting corrosion by adding corrosion inhibitors C23F11/00) · CPC title

• C23F11/122

  Alcohols; Aldehydes; Ketones · CPC title

• G21D1/04

  Pumping arrangements (within the reactor pressure vessel G21C15/24; electrodynamic pumps H02K44/02) · CPC title

• G21C19/307

  specially adapted for liquids (decontamination of liquids G21F9/04) · CPC title

• Y02E30/30

  Nuclear fission reactors · CPC title