JP2865265B2 - Primary water quality monitoring system for boiling water reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

 [Object of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primary water quality monitoring apparatus for predicting and monitoring changes in reactor water quality due to condensed organic matter in a boiling water nuclear power plant (hereinafter referred to as a BWR nuclear power plant).

[0002]

2. Description of the Related Art In general, in-line water quality monitoring of primary cooling water of a BWR nuclear power plant is limited to the conductivity of reactor water, pH, dissolved oxygen concentration, and the conductivity of feed water and condensate, and dissolved oxygen concentration. When a conductivity abnormality occurs, the water is sampled and analyzed for ion concentration and organic carbon (TOC) concentration.

[0003] If organic matter is present as impurities in the condensate, such organic impurities are decomposed into ions after entering the reactor, resulting in an increase in the reactor water conductivity. It cannot be predicted by ion analysis and TOC analysis in the analysis system.

[0004]

As described above, in the prior art, when organic matter is present as an impurity in condensate, it is impossible to predict how the organic impurity will behave in the reactor. After the occurrence of an abnormality in the conductivity of water, it was only necessary to investigate the cause. That is,
There was no water quality monitoring system that could take precautionary measures.

[0005] The present invention has been made in view of such a point, and in the condensate sampling and analysis system, it is determined in advance how condensate organic impurities are decomposed in the furnace and what effect on the reactor water quality. It is an object of the present invention to provide a primary water quality monitoring device for detecting and predicting water quality. [Configuration of the Invention]

[0006]

That is, a primary water quality monitoring device of the present invention comprises a condensate sampling line for collecting condensate at an outlet of a condensate purification system of a boiling water reactor, and a condensate sampling line for collecting condensate. An organic matter decomposing section for decomposing organic impurities in the condensate sample collected through the reactor, a decomposition product analyzing section for analyzing decomposition products generated in the organic substance decomposing section and measuring the concentration thereof; An analysis data processor for predicting a change in reactor water quality due to organic impurities based on an analysis result of the analyzer is provided.

[0007]

[Function] Of the organic impurities in the condensate, those containing sulfur or nitrogen in the molecules are decomposed in the furnace and converted into sulfuric acid or nitric acid, which contributes to an increase in electrical conductivity. The effect on conductivity is small, and it is difficult to detect the compound because it is not constant as a compound.

Therefore, in the present invention, the condensate at the outlet of the condensate purification system is collected and introduced into an organic matter decomposition treatment section simulating the furnace environment, where the organic matter is converted into inorganic ions such as sulfate ions and nitrate ions. I do. Inorganic ions are easier to analyze and have higher sensitivity than organic substances. Then, the conductivity of the condensed water after the organic substance decomposition treatment is measured in the decomposition product analysis section, and the ion species and ion concentration are measured. In the analysis data processing unit, these measured values are input to the mass balance method together with process values such as reactor water volume (reactor water level), condensate flow rate, reactor water purification system flow rate, and reactor water purification system removal rate. Changes in ion concentration and conductivity are predicted by calculation.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a primary water quality monitoring device according to an embodiment of the present invention. In the figure, as shown by the solid line, the main steam generated in the reactor 1 is guided to the turbine and performs work, and then condensed in the condenser 2 to be condensed and purified by a desalination tower. Water is supplied again into the reactor 1 via the condensing line 4 via the system 3. Further, the reactor water is recirculated in a reactor water purification system loop provided with the reactor water purification system 5. The condensing line 4 is branched and provided with a sampling line 6. The sampling line 6 is provided with an organic matter decomposition processing unit 7 having an ultraviolet irradiation device.
A decomposition product analyzer 10 having a conductivity meter 8 and an ion chromatograph device 9, and an analysis data processor for calculating a change in ion concentration and conductivity of reactor water from the analysis result of the decomposition product analyzer 10. 11 are installed, and these constitute a primary water quality monitoring device.

In such a configuration, the condensate purification system 3
Mouth condensate sampled by sampling line 6
Then, it is first introduced into the organic matter decomposition processing section 7. This organic
Organic matter present in the condensed water in the material decomposition processing section 7 is irradiated with ultraviolet rays
Decomposed by carbon dioxide, water and sulfate ions and nitric acid
Turns into inorganic ions such as ions. For example, the cationic tree
Aromatic sulfonic acid, which is the main eluate from fat, is as follows:
Chemical formula R-SO_ThreeH → nCO_Two↑ + mH_TwoO + H_TwoSO_Four  Is converted to sulfuric acid.

An inorganic ion component such as sulfuric acid, which is a decomposition product of an organic substance, is easily identified and quantified by an ion chromatograph device 9 in a decomposition product analyzing section 10, and the conductivity is also measured.

These measured values are stored in the analysis data processing unit 11.
In the case where the decomposition product is sulfuric acid,⁺ Equivalent ion of
Conductivity λ₊= 349.8 S.cm^Two .mol^-1And 1 / 2SO_Four ^2-of
Equivalent ion conductivity λ_-= 80S.cm^Two .mol^-1From Crossche
Reactor water level 12, condensate flow rate 13, reactor water
Values such as purification system flow rate 14 and reactor water purification system removal rate were also introduced.
Then, the reactor water sulfuric acid concentration and reactor water conductivity are predicted by the following equations.
You. V_o dC / dt = C₁F₁-CF_Two+ C_TwoF_Two  Where V_o: Furnace water amount C: Furnace water sulfuric acid concentration C₁: Concentration of impurities in condensate (converted to sulfuric acid) C_Two： Sulfuric acid concentration at outlet of reactor water purification system F₁: Condensate flow rate F_Two： Flow rate of reactor water purification system t ： Time

For example, when a sulfuric acid concentration of 10 ppb is detected in the decomposition product analysis section 11 from the condensate of a 1100 MW BWR (outlet of the condensate desalination tower), a reactor water volume of 235 tons and a condensate flow rate of 6200 Ton / h, reactor water purification system flow rate 122 ton / h, reactor water purification system removal rate 100%, and assuming how much the sulfuric acid concentration in the reactor water increases, from the above mass balance, C =
It becomes 510ppb. When the reactor water conductivity is calculated using the equivalent ionic conductivity, it is found that the reactor water conductivity increases to 2.3 μS / cm.

In the above embodiment, an ultraviolet irradiation device is used as the organic substance decomposing means. However, a thermal decomposition device may be used instead. Further, in addition to the ion chromatograph device 9 and the conductivity meter 8, a pH meter, a TOC meter, and the like may be added to the decomposition product analyzer 10 as necessary.

[0016]

As described above, according to the present invention, fluctuations in the water quality of the reactor water due to the contamination of organic matter can be predicted from the water quality monitoring of the condensate system before it occurs, and by taking preventive measures, The quality of the BWR primary cooling water can be constantly maintained at a high purity.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a primary water quality monitoring device of the present invention.

[Description of Signs] 1 ... Reactor 2 ... Condenser 3 ... Condensate purification system 4 ... Condensation line 5 ... Reactor water purification system 6 ... Sampling line 10 ... Decomposition product analyzer 11 Analysis data processor 12 Reactor water level 13 Condensate flow rate 14 Reactor water purification system flow rate

Claims (1)

(57) [Claims] 1. A condensate sampling line for collecting condensate at the outlet of a condensate purification system of a boiling water reactor, and an organic matter decomposing unit for decomposing organic impurities in a condensate sample collected through the condensate sample line. Processing section, a decomposition product analysis section for analyzing the decomposition products generated in the organic substance decomposition processing section and measuring the concentration thereof, and water quality of the reactor water due to the organic impurities based on the analysis result of the decomposition product analysis section. An apparatus for monitoring primary water quality of a boiling water reactor, comprising: an analysis data processor for predicting a change.