A method for calculating the off-core power of a nuclear power plant
By adjusting the steam generator water level and calculating the enthalpy of wet steam, the error problem in calculating the thermal power of nuclear power plants other than the reactor core was solved, achieving higher calculation accuracy and result precision.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CNNC FUJIAN FUQING NUCLEAR POWER
- Filing Date
- 2023-06-26
- Publication Date
- 2026-06-09
AI Technical Summary
Current technology cannot accurately calculate the thermal power output of a nuclear power plant excluding the reactor core, which affects reactor safety and economic efficiency and results in significant errors.
By adjusting the steam generator water level to a high level and closing the drain valve to maintain stable pressure, the heat carried out by the steam is calculated using the rate of decrease in the steam generator water level. Combined with the physical properties of water and steam, the enthalpy of wet steam is calculated, and then the heat power input to the coolant system from other heat sources besides the reactor core is calculated.
It improved the calculation accuracy of output power excluding the reactor core, reduced experimental data errors, and enhanced the accuracy of calculation results.
Smart Images
Figure CN116796539B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nuclear power plant power calculation technology, specifically relating to a method for calculating the output power of a nuclear power plant excluding the reactor core. Background Technology
[0002] During the operation of nuclear power plants, it is required that the steady-state thermal power of the reactor core does not exceed 100% Pn during continuous operation. However, the actual thermal power calculated through the secondary loop thermal balance includes the power exported from the reactor core to the secondary loop, and the core thermal power cannot be directly calculated. Therefore, the steady-state thermal power of the reactor core needs to be obtained by subtracting the power exported from the reactor core to the secondary loop from the secondary loop thermal power. The accuracy of the power exported from the reactor core to the secondary loop directly affects the safety and economy of the reactor. The current common practice is to give an empirical value of 11MW, or to obtain it by subtracting heat loss from the heat introduced by the main pump and other equipment according to theoretical calculations, but the error is relatively large. Summary of the Invention
[0003] The purpose of this invention is to provide a method for calculating the output power of a nuclear power plant excluding the reactor core, which can effectively improve the accuracy of the results.
[0004] The technical solution of the present invention is as follows: A method for calculating the output power of a nuclear power plant excluding the reactor core, comprising the following steps:
[0005] Step 1: Obtain the parameters of the steam generator equipment;
[0006] Step 2: Adjust the water level in the steam generator to the high level, close the steam generator drain valve and water supply, and maintain the steam generator pressure P;
[0007] Step 3: Obtain relevant calculation data:
[0008] Step 4: Calculate the heat carried out by the steam generator.
[0009] The parameters in step 1 include the inner radius r of the upper cylinder of the steam generator = 2.14 and the steam content x at the outlet of the steam generator = 99%.
[0010] Step 3 involves obtaining the curve of the steam generator water level changing over time during the experiment (this can be done via online instruments or by manually recording the water level at regular intervals), and selecting an interval with a good linear segment (R² > 0.5). Figure 2 Calculate the slope during that time period.
[0011] In step 3, based on the physical properties of water and water vapor, the saturated water density, saturated water enthalpy Hes, and saturated steam enthalpy Hvs at the maintained steam generator pressure P are found or calculated.
[0012] In step 3, the wet vapor enthalpy Hv is calculated.
[0013] In step 4, the heat carried out by the steam generator is calculated.
[0014] W SG =cπr 2 h(Hv-Hes).
[0015] In step 4 mentioned above
[0016] Assuming the reactor has 3 steam generators, and the parameters of all 3 generators change in the same way as described above, then: WΔP r =∑W SGi =3W SG .
[0017] The beneficial effects of this invention are as follows: It provides a method for directly measuring the thermal power input to the coolant system from heat sources other than the reactor core. By obtaining the unique and highly accurate variable, hi, which represents the rate of decrease in the steam generator water level during the test, the error in the test data can be reduced, thereby reducing the error in the thermal power. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of a steam generator;
[0019] Figure 2 This is a schematic diagram showing the change in water level in a steam generator over time. Detailed Implementation
[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0021] This is executed during reactor hot shutdown or after the first cycle of fuel loading. Once all equipment and primary and secondary loop parameters are stable, and the reactor core is not heating up, the following relationship exists:
[0022] WΔP r =∑W SGi (1)
[0023] Where: wΔP r : Thermal power input to the coolant system from heat sources other than the reactor core, W SGi : Power output from the steam generator SGi.
[0024] That is, the heat power input to the coolant system from heat sources other than the reactor core is equal to the sum of the power carried out by the steam generator. Analyze the heat transfer of the steam generator at this time as follows: Figure 1 .
[0025] The heat transfer of a steam generator can be calculated using heat transfer formulas. Starting from the primary loop, the following formula can be used for calculation:
[0026] WΔPr =cm(T) in -T out (2)
[0027] This method can also directly calculate the thermal power input to the coolant system from other heat sources outside the reactor core. However, since the power is relatively small, the flow rate is relatively large, and even small fluctuations in the measurements of Tin and Tout can cause large deviations, this method is not recommended for calculation.
[0028] Starting from the second loop, a similar method to that used for the first loop can be employed for calculation:
[0029] W SGi =cm(t) in -t out (3)
[0030] Similarly, due to the relatively small power, the water supply flow rate fluctuates greatly, and t in and t out Measuring even small fluctuations can cause large deviations, so this method is not recommended for calculation.
[0031] The present invention uses the following method to calculate the thermal power: before the test, the water level of the steam generator is adjusted to a high level and operated stably. During the test, the steam pressure is kept stable, and the water supply and steam generator drain are closed, so that no water flows in or out of the steam generator except for steam. Since the steam generator contains saturated steam and saturated water, the heat is carried out by the phase change of the water in the steam generator. By obtaining the rate of linear change of the water level in the steam generator, the heat carried out by the steam generator can be calculated.
[0032] Assuming the radius of the water level change section in the steam generator is r, the steam pressure during the experiment is P, the steam content at the steam generator outlet is x, and the rate of water level drop in the steam generator during the experiment is h, then the enthalpy of saturated water Hes and the enthalpy of saturated steam Hvs at steam pressure P can be found through the physical properties of water and steam. Therefore, the enthalpy of wet steam Hv = x Hvs + (1-x)Hes. The density of saturated water is c.
[0033] The power output of this steam generator is:
[0034] W SG =cπr 2 h(Hv-H es (4)
[0035] The heat power carried out by all steam generators is calculated using the above method and substituted into formula (1) to obtain the heat power input to the coolant system from heat sources other than the reactor core.
[0036] A method for calculating the output power of a nuclear power plant excluding the reactor core includes the following steps:
[0037] Step 1: Obtain the equipment parameters of the steam generator, as shown in the table below:
[0038]
[0039] Step 2: Adjust the water level of the steam generator to the high water level, close the steam generator drain valve and water supply, and maintain the steam generator pressure P, such as keeping the evaporator pressure P at 7.5MPa;
[0040] Step 3: Obtain relevant calculation data:
[0041] Obtain the curve of the steam generator water level changing over time during the experiment (this can be done via online instruments or by manually recording the water level at regular intervals), and select an interval with good linearity (R-squared > 0.5). Figure 2 As shown, calculate the slope over this time period. Figure 2 The slope shown is 1 m / h, or 1 / 3600 m / s.
[0042] Based on the physical properties of water and water vapor, find or calculate the density of saturated water at P = 7.5 MPa: 730.88 kg / m³. 3 The enthalpy of saturated water, Hes, is 1292.696 kJ / kg, and the enthalpy of saturated steam, Hvs, is 2765.820 kJ / kg. Therefore, the enthalpy of wet steam, Hv, is 0.99 * 2765.820 + (1 - 0.99) * 1292.696 = 2751.09 kJ / kg.
[0043] Step 4: Calculate the heat carried out by the steam generator
[0044] Calculate the heat carried out by the steam generator according to formula (4).
[0045] W SG =cπr 2 h(Hv-Hes)=730.88*3.14159*2.142*1 / 3600*(2751.09-1292.696)=4259.86kW=4.25986MW
[0046] Assuming the reactor has 3 steam generators, and the parameters of all 3 generators change in the same way as described above, then: WΔP r =∑W SGi =3W SG =3 * 4.25986 MW = 12.78 MW.
Claims
1. A method for calculating the output power of a nuclear power plant excluding the reactor core, characterized in that, Includes the following steps: Step 1: Obtain the parameters of the steam generator equipment; The parameters in step 1 include the inner radius of the upper cylinder of the steam generator r = 2.14 m, and the steam content at the steam generator outlet x = 99%; Step 2: Adjust the water level in the steam generator to the high level, close the steam generator drain valve and water supply, and maintain the steam generator pressure P; Step 3: Obtain relevant calculation data; Step 3 obtains the curve of the steam generator water level changing with time during the test, selects the interval with good linearity, and obtains the rate of decrease of the steam generator water level as h. In step 3, based on the physical properties of water and water vapor, the saturated water density c, saturated water enthalpy Hes, and saturated steam enthalpy Hvs are found or calculated at the maintained steam generator pressure P. In step 3, the wet vapor enthalpy Hv is calculated as Hv = x Hvs + (1-x)Hes; Step 4: Calculate the heat carried out by the steam generator; In step 4, the heat carried out by the steam generator is calculated. 。