REAL-TIME REACTOR COOLANT SYSTEM BORON CONCENTRATION MONITOR UTILIZING AN ULTRASONIC SPECTROSCPOPY SYSTEM

Abstract

A method and a system for performing real-time, continuous, measurements of the boron concentration in the water entering a nuclear reactor coolant system. The invention utilizes knowledge of the impact that boron contained in liquid water has on the attenuation of acoustic or ultrasonic waves. This information, coupled with radiation damage resistant and high temperature operability capable transmitter and receiver equipment, provides the means to place the measurement system sensors and signal processing electronics on the reactor coolant system charging flow piping or the hot leg or cold leg of the reactor coolant loop. This will allow the reactor operator to directly monitor both the reactor coolant system boron concentration value and detect changes in the reactor coolant system boron concentration relative to a reference value as they occur.

Claims

1. A boron concentration monitor for measuring, in real time, the boron concentration of coolant within a piping servicing a primary loop of a nuclear reactor comprising: an acoustic transmitter acoustically coupled to or through the piping operable to transmit an acoustic signal substantially through an interior of the piping; an acoustic receiver supported at a location around a circumference of the piping that is spaced from the acoustic transmitter, for receiving the acoustic signal; a communication mechanism in electrical communication with the acoustic transmitter and the acoustic receiver and configured to convey the transmitted acoustic signal and the received acoustic signal to a remote location; and an analyzer is structured to be in communication with the remote location and is configured to receive the received acoustic signal and the transmitted acoustic signal from the communication mechanism and compare the received acoustic signal and the transmitted acoustic signal and from the comparison determine the boron concentration within the piping.

2. The boron concentration monitor of claim 1 wherein the analyzer compares the signal comparison to a standard to determine the boron concentration in the piping.

3. The boron concentration monitor of claim 2 wherein the acoustic transmitter and acoustic receiver are at a known linear distance from each other and the standard is established from an experimental determination of the attenuation of an acoustic signal in a borated water solution over the known distance at a plurality of known boron concentrations.

4. The boron concentration monitor of claim 1 wherein the communication mechanism comprises: a wireless transmitter coupled to the acoustic transmitter and the acoustic receiver and configured to wirelessly transmit both the transmitted acoustic signal and the received acoustic signal to the remote location; and a wireless receiver configured to receive the wirelessly transmitted acoustic signal and received acoustic signal and communicate the transmitted acoustic signal and the received acoustic signal to the analyzer at the remote location.

5. The boron concentration monitor of claim 4 wherein the acoustic transmitter, the acoustic receiver and the wireless transmitter are powered from a thermoelectric generator having a hot junction in thermal communication with the piping and a cold junction in thermal communication with a surrounding environment.

6. The boron concentration monitor of claim 5 wherein the hot junction is in thermal communication with the piping through a heat pipe.

7. The boron concentration monitor of claim 4 wherein the wireless transmitter comprises two separate wireless transmitters respectively connected to the acoustic transmitter and the acoustic receiver.

8. The boron concentration monitor of claim 1 wherein the acoustic transmitter and the acoustic receiver are supported at substantially diametrically opposite positions around the circumference of the piping.

9. The boron concentration monitor of claim 1 wherein the acoustic transmitter and the acoustic receiver employ one or more vacuum micro-electronic devices.

10. The boron concentration monitor of claim 9 wherein the solid state vacuum device is a vacuum micro-electronic device.

11. The boron concentration monitor of claim 4 wherein the wireless transmitter employs one or more vacuum micro-electronic devices.

12. The boron concentration monitor of claim 11 wherein the solid state vacuum device is a vacuum micro-electronic device.

13. The boron concentration monitor of claim 1 wherein the acoustic receiver is an ultrasonic energy measurement sensor.

14. The boron concentration monitor of claim 1 wherein the piping is a charging line in fluid communication with the primary loop.

15. The boron concentration monitor of claim 1 wherein the piping is a hot leg or a cold leg of the primary loop of the nuclear reactor.

16. The boron concentration monitor of claim 1 including a temperature sensor for determining a temperature of water flowing in the piping at the location of the acoustic transmitter and acoustic receiver and transmitting a signal representative of the temperature through the communication mechanism to the analyzer which determines the boron concentration as a function of temperature.

17. The boron concentration monitor of claim 14 including a pressure sensor for determining a pressure of the water flowing in the piping at the location of the acoustic transmitter and acoustic receiver and transmitting a signal representative of the pressure through the communication mechanism to the analyzer which determines the boron concentration as a function of temperature and pressure.

18. A method of monitoring a boron concentration of a borated water solution in real-time, comprising the steps of: transmitting an acoustic signal through the borated water solution; receiving the transmitted acoustic signal after the transmitted acoustic signal has passed through at least a portion of the borated water solution, at a known distance between a transmitter structured to transmit the acoustic signal and a receiver configured to receive the transmitted acoustic signal; comparing the received acoustic signal to the transmitted acoustic signal to determine an attenuation of the transmitted acoustic signal through the borated water solution; and determining the boron concentration from the attenuation of the transmitted signal.

19. The method of claim 18 wherein the determining step compares the attenuation with a standard obtained by chemically analyzing a plurality of different concentrations of boron in borated water solutions and measuring the attenuation over the known distance in each of the plurality of different concentrations of boron.

20. The method of claim 18 wherein the determining step comprises: obtaining the pressure and temperature of the coolant at a time of transmission of the acoustic signal; and using the attenuation, the temperature and the pressure to mathematically determine the boron concentration in real-time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] A further understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:

[0019] FIG. 1 is a simplified schematic of a nuclear reactor system to which this invention can be applied;

[0020] FIG. 2 is an elevational view, partially in section, of a nuclear reactor vessel and internals components to which this invention can be applied; and

[0021] FIG. 3 is schematic of a cross-section of an exemplary reactor system piping with the devices of one embodiment of this invention shown in block form.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0022] A preferred embodiment of this invention is illustrated in FIG. 3. The system comprises one or more pairs of ultrasonic transmitter 56 and ultrasonic energy measurement sensors or receivers 58 coupled with wireless transmitters 60, 62 that broadcasts a signal representing the intensity of the transmitted and received ultrasonic energy. The ultrasonic transmitter 56 and receiver 58 are coupled directly to the surface of the piping containing the fluid. The wireless signal transmitter 60, 62 is positioned on the insulation 64 surrounding the piping 66. The power 72 required by the ultrasonic transmitter 56 and the wireless signal transmitter 60, 62 is generated via one or more thermo-electric generators 68 that have the heated junction connected to a heat pipe 70 that penetrates the insulation 64 surrounding the piping 66 and a cold junction located on or above the outer surface of the insulation 64 on the piping 66. Alternatively, it should be appreciated that the hot junction of the thermoelectric generator 68 can be directly connected to the piping 66. The transmitted frequency used is selected to optimize the ability of the system to measure and detect changes in the boron concentration. An embodiment of this system can be used to track changes in bulk temperature corrected transmitted signal intensity and convert the changes in intensity to changes in boron concentration relative to a periodically manually updated reference established from current boron concentration titration measurements using existing methods.

[0023] The system can be installed on either the reactor coolant system hot or cold leg piping or the charging line providing flow into the reactor coolant system. An alternate embodiment would be the installation of the hardware on the pressurizer surge line piping 21. The preferred embodiment of the sensors, signal processing, and transmission electronics devices utilizes vacuum micro-electronic device based electronics and materials. Such devices, known as SSVDs, are commercially available from Innosys Inc., Salt Lake City, Utah. An example of such a device can be found in U.S. Pat. No. 7,005,783. An alternate embodiment would be to use less radiation and temperature tolerant materials and will require an increase in the required maintenance cycle. Another embodiment would allow the use of power and/or signal cables to provide transmitter power or receive transmitter and receiver output data. The measured signals are filtered to remove electronic noise in an analyzer 74 to meet user defined accuracy requirements using techniques well known to those skilled in the art.

[0024] An example of the parameters required to develop a correlation between the boron concentration in the reactor coolant system and the attenuation of the transmitted acoustic or ultrasonic energy is contained in an article entitled “Modeling of Acoustic Wave Absorption in Ocean” by T. B. Mohite-Patil, et al. International Journal of Computer Applications, November 2010:

[0025] Absorption coefficient due to Boric Acid

[00001]$\begin{array}{cc}{\mathrm{attn}}_1=\frac{A_1.Math.P_1.Math.f_1.Math.f^2}{f_1^2+f^2}& \\ A_1=\frac{8.86}{c}\times {10}^{\left(0.78.Math..Math.\mathrm{pH}-S\right)},& \mathrm{dB}.Math..Math.{\mathrm{Km}}^{-1}.Math.{\mathrm{KHz}}^{-1}\\ P_1=1,& \\ f_1=2.8.Math.{\left(S/35\right)}^{0.5}\times {10}^{\left(4-1245/\theta \right)},& \mathrm{KHz}\end{array}$

[0026] Where c is the sound speed (m/s), given by

[0027] c=1412+3.21T+1.19 S+0.0167 D,

[0028] T is the temperature(°C.),

[0029] θ=273+T,

[0030] S is the salinity(‰), and D is the depth (m).

[0031] The boron concentration in the liquid is obtained by solving the relationship for pH of the liquid and converting the pH information to boron concentration using the known properties of boron in an aqueous solution. Temperature and Pressure (Depth) information can be determined from existing sensors. Salinity (S) is determined based on known water properties. The frequency used is selected to optimize the ability to measure and detect changes in the boron concentration. Thus, the boron concentration can be determined by comparing the attenuation of the transmitted signal over a known travel path through the coolant with a standard obtained by transmitting a like acoustic signal over the known travel path through a plurality of different boron concentrations in water solutions with the concentrations determined by conventional chemical analysis. Alternatively, with the pressure and temperature of the coolant known a real-time reading of the boron concentration can be had from a computer mathematical analysis from the foregoing mathematical correlation.

[0032] While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular embodiments disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof