METHOD FOR MEASURING DROP TIME OF A CONTROL ROD CLUSTER INTEGRATED WITH A ROD POSITION MEASUREMENT DEVICE

Abstract

A method for measuring drop time of a control rod cluster integrated with a rod position measurement device is provided, wherein the method is used to measure the drop time of each control rod cluster, and includes: Si, monitoring a voltage Ua of coils in Group A to capture a rod cluster drop signal; S2, searching a point (tmax, Vmax) with a maximum drop speed or with a local maximum drop speed; S3, retroactively calculating, from tmax, an end of a time period T4 when the control rod cluster starts to drop; S4, retroactively searching, from a minimum value point of a drop reference signal DROPref, a start of the time period T4 when the drop reference signal DROPref drops from a maximum value to 33% thereof; and S5, determining, from tmax forward, a time point t6 when a drop speed of the control rod cluster is lower than 0.

Claims

1. A method for measuring drop time of a control rod cluster integrated with a rod position measurement device, wherein the method is used to measure the drop time of each control rod cluster, and comprises: S1, monitoring a voltage Ua of coils in Group A to capture a rod cluster drop signal; S2, searching a point (tmax, Vmax) with a maximum drop speed or with a local maximum drop speed; S3, retroactively calculating, from tmax, an end of a time period T4 when the control rod cluster starts to drop; S4, retroactively searching, from a minimum value point of a drop reference signal DROPref, a start of the time period T4 when the drop reference signal DROPref drops from a maximum value to 33% of the maximum value; S5, determining, from tmax forward, a time point t6 when a drop speed of the control rod cluster is lower than 0; S6, calculating an end of a time period T6 when the drop speed of the control rod cluster is 0; S7, searching an end of a time period T5 when the drop speed of the control rod cluster drops rapidly; S8, calculating a time point t7 when the drop speed returns to 0 after t6; S9, calculating a time point t8 when the drop speed returns to 0 after t7; S10, calculating a time point t9 when the drop speed returns to 0 after t8; and S11, obtaining an analysis result, and saving and outputting the analysis result in a form of file.

2. The method according to claim 1, wherein S1 comprises: S1.1, performing digital filtering on the voltage Ua of the coils in Group A to obtain a first filtered voltage; S1.2, transforming a waveform of the first filtered voltage into broken lines and removing outlier points on the broken lines; S1.3, calculating a first median sequence; S1.4, searching a first minimal value point P2 (tmin, Vmin) of the first median sequence; S1.5, searching backward, from the first minimal value point, a median point P1 with a value smaller than Vmin/2; S1.6, determining a point P0 where a line connecting the first minimal value point P2 and the median point P1 intersects with a 0-axis; and S1.7, if a slope of a line connecting P0 and P2, a time difference between P0 and P2, and an amplitude difference between P0 and P2 are within predetermined ranges respectively, determining that the control rod cluster starts to drop.

3. The method according to claim 1, wherein S2 comprises: S2.1, performing digital filtering on a voltage Up of a primary coil to obtain a second filtered voltage; S2.2, transforming a waveform of the second filtered voltage into broken lines and removing outlier points on the broken lines; S2.3, calculating a second median sequence; S2.4, searching among the second median sequence a point P1, wherein absolute values of the point P1 and preceding three points of the point P1 exceed 0.5; S2.5, if a value of P1 is negative, inverting the second median sequence; S2.6, searching backward, from P1, a point P0 with a value smaller than or equal to 0, and searching forward, from P1, a point P2 with a value smaller than or equal to 0; and S2.7, calculating a maximal value among a section between P0 and P2 to obtain Pmax (tmax, Vmax).

4. The method according to claim 3, wherein S3 comprises: retroactively searching, from tmax, a point P04 with an amplitude smaller than 0.4*Vmax, retroactively searching, from tmax, a point P02 with an amplitude smaller than 0.2*Vmax, and determining an end of the time period T4 where a line connecting P04 and P02 intersects with a 0-axis.

5. The method according to claim 4, wherein S4 comprises: obtaining a subsequence of a value sequence corresponding to the drop reference signal DROPref before tmax, determining a minimum value point and a maximum value point of the subsequence, and searching backward, from the minimum value point, a point with a value greater than 33% of a maximum value of the subsequence.

6. The method according to claim 5, wherein S5 comprises: searching, among the second median sequence and from tmax, a point with a value smaller than 0, and setting a time point corresponding to the point to be t6.

7. The method according to claim 6, wherein S6 comprises: determining a point where a line connecting a point corresponding to t6 and a point corresponding to (t6-1) inserts with the 0-axis as an end t6 of the time period T6.

8. The method according to claim 7, wherein S7 comprises: S7.1, retroactively searching, from t6, a point P05 with an amplitude greater than 50% of Vmax; S7.2, retroactively searching, from t6, a point P075 with an amplitude greater than 75% of Vmax; S7.3, determining a horizontal line Line1 passing through Pmax (tmax, Vmax); S7.4, determining a straight line Line2 passing through P05 and P075; and S7.5, determining a point where Line1 intersects with Line2, wherein a time point corresponding to the point is an end of the time period T5.

9. The method according to claim 8, wherein S11 comprises: S11.1, calculating the time period T4 by subtracting the start of T4 from the end of T4, calculating the time period T5 by subtracting the end of T4 from the end of T5, and calculating the time period T6 by subtracting the end of T5 from the end of T6; S11.2, verifying that T4, T5, T6 are within a threshold range; S11.3, verifying positivity of t7, t8 and t9; and S11.4: saving and outputting calculation results in the form of file.

10. The method according to claim 2, wherein S2 comprises: S2.1, performing digital filtering on a voltage Up of a primary coil to obtain a second filtered voltage; S2.2, transforming a waveform of the second filtered voltage into broken lines and removing outlier points on the broken lines; S2.3, calculating a second median sequence; S2.4, searching among the second median sequence a point P1, wherein absolute values of the point P1 and preceding three points of the point P1 exceed 0.5; S2.5, if a value of P1 is negative, inverting the second median sequence; S2.6, searching backward, from P1, a point P0 with a value smaller than or equal to 0, and searching forward, from P1, a point P2 with a value smaller than or equal to 0; and S2.7, calculating a maximal value among a section between P0 and P2 to obtain Pmax (tmax, Vmax).

11. The method according to claim 10, wherein S3 comprises: retroactively searching, from tmax, a point P04 with an amplitude smaller than 0.4*Vmax, retroactively searching, from tmax, a point P02 with an amplitude smaller than 0.2*Vmax, and determining an end of the time period T4 where a line connecting P04 and P02 intersects with a 0-axis.

12. The method according to claim 11, wherein S4 comprises: obtaining a subsequence of a value sequence corresponding to the drop reference signal DROPref before tmax, determining a minimum value point and a maximum value point of the subsequence, and searching backward, from the minimum value point, a point with a value greater than 33% of a maximum value of the subsequence.

13. The method according to claim 12, wherein S5 comprises: searching, among the second median sequence and from tmax, a point with a value smaller than 0, and setting a time point corresponding to the point to be t6.

14. The method according to claim 13, wherein S6 comprises: determining a point where a line connecting a point corresponding to t6 and a point corresponding to (t6-1) inserts with the 0-axis as an end t6 of the time period T6.

15. The method according to claim 14, wherein S7 comprises: S7.1, retroactively searching, from t6, a point P05 with an amplitude greater than 50% of Vmax; S7.2, retroactively searching, from t6, a point P075 with an amplitude greater than 75% of Vmax; S7.3, determining a horizontal line Line1 passing through Pmax (tmax, Vmax); S7.4, determining a straight line Line2 passing through P05 and P075; and S7.5, determining a point where Line1 intersects with Line2, wherein a time point corresponding to the point is an end of the time period T5.

16. The method according to claim 15, wherein S11 comprises: S11.1, calculating the time period T4 by subtracting the start of T4 from the end of T4, calculating the time period T5 by subtracting the end of T4 from the end of T5, and calculating the time period T6 by subtracting the end of T5 from the end of T6; S11.2, verifying that T4, T5, T6 are within a threshold range; S11.3, verifying positivity of t7, t8 and t9; and S11.4: saving and outputting calculation results in the form of file.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 is a structural diagram of a CRDM;

[0046] FIG. 2A is a schematic diagram of drop time of a control rod cluster, where T4 is a time period between a time point when a holding coil current falls to 33% of a rated value and a time point when the control rod cluster starts to drop, and is shorter than 150 ms, T5 is a time period between a time point when the control rod cluster starts to drop and a time point when the control rod cluster enters a buffer section. T6 is a time period between a time point when the control rod cluster enters the buffer section and a time point when the control rod cluster reaches bottom of the buffer section, T4+T5+T6 in a hot state is shorter than 3s.

[0047] FIG. 2B is a schematic diagram of characteristic points of a rod drop waveform;

[0048] FIG. 3 illustrates arrangement and connection of coils of a rod position detector;

[0049] FIG. 4 is a structural diagram of a rod position measurement device according to an embodiment;

[0050] FIG. 5A is a schematic diagram of characteristic points of a rod drop waveform according to an embodiment;

[0051] FIG. 5B is a schematic diagram of a calculation and analysis result of a drop time of a control rod cluster according to an embodiment;

[0052] FIG. 6 is a flow chart of measurement and analysis of drop time of a control rod cluster according to an embodiment;

[0053] FIG. 7A is a flow chart of capturing a rod cluster drop signal according to an embodiment;

[0054] FIG. 7B is a schematic diagram of a rod cluster drop waveform according to an embodiment;

[0055] FIG. 8 is a flow chart of searching a maximum drop speed or a local maximum drop speed according to an embodiment;

[0056] FIG. 9 is a flow chart of searching a time point when a drop speed of a control rod cluster drops rapidly according to an embodiment; and

[0057] FIG. 10 is a schematic diagram of a calculation and analysis result of chop time of a control rod cluster according to an embodiment.

[0058] The analysis result is that there is a drop of a control rod cluster caused by normal power off.

[0059] Referring to the figures, through Up induced voltage analysis, the result is normal.

[0060] The drop reference signal is normal.

[0061] T4=0.062 noir Jai <=0.15,

[0062] T5=1.2855 normal <=2.4,

[0063] T5?T6=1.778 normal <=3.2;

[0064] A first bounce at T7 is normal.

[0065] A duration T7 of the bounce is normal.

[0066] A second bottoming at T8 is normal.

[0067] A second bounce at T9 is normal.

[0068] Detailed data are as follows.

[0069] t0=20200309 194540.313 dt=0.0005;

[0070] T4Bgn-440 (when DROPref falls to 80% of its maximum value);

[0071] T4Bgn 446 (start of T4: when DROPref drops to 33% of its maximum value);

[0072] T4End 564 (end of T4: a point where a line connecting a point corresponding to 40% of Vmax and a point corresponding to 20% of Vmax intersects with a horizontal axis);

[0073] T5End 3135 (end of T5: a point where a line connecting a point corresponding to 75% of Vmax and a point corresponding to 50% of Vmax intersects with a horizontal line passing through Vmax);

[0074] T6End 4120 (end of T6: a point of a line connecting a point which has a value smaller than 0 for the first time after Vmax and corresponds to t6 with a preceding point of the point intersects with the horizontal axis;); T7End 4337 (t7: a point greater than 0 for the first time after t6);

[0075] T8End 4573 (t8: a point smaller than or equal to 0 for the first time after t7);

[0076] T9End 4750 (t9: a point greater than 0 for the first time after t8);

[0077] T4+0.062 (T4End-T4Bgn-when DROPref drops to 80% of its maximum value;

[0078] T4 0.059 (T4End-T4Bgn when DROPref drops to 33% of its maximum value);

[0079] T5 1.2855 (T5End-T4End);

[0080] T6 0.4925 (T6End-T5End);

[0081] T56 1.778 (T5+T6);

[0082] T7 0.1085 (t7-T6End);

[0083] T8 0.118 (t8-t7);

[0084] T9 0.0885 (t9-t8).

BEST EMBODIMENTS

Detailed Description

[0085] Embodiments of the present disclosure provide a method for measuring drop time of a control rod cluster integrated with a rod position measurement device. Specific implement ways of the present disclosure will be described in detail in conjunction with embodiments.

[0086] Referring to FIG. 1 to FIG. 10, FIG. 1 is a structural diagram of a CRDM; FIG. 2A is a schematic diagram of drop time of a control rod cluster; FIG. 2B is a schematic diagram of characteristic points of a rod drop waveform; FIG. 3 illustrates arrangement and connection of coils of a rod position detector; FIG. 4 is a structural diagram of a rod position measurement device according to an embodiment; FIG. 5A is a schematic diagram of characteristic points of a rod drop waveform according to an embodiment; FIG. 5B is a schematic diagram of a calculation and analysis result of a drop time of a control rod cluster according to an embodiment; FIG. 6 is a flow chart of measurement and analysis of drop time of a control rod cluster according to an embodiment; FIG. 7A is a flow chart of capturing a rod cluster drop signal according to an embodiment; FIG. 7B is a schematic diagram of a rod cluster drop waveform according to an embodiment; FIG. 8 is a flow chart of searching a maximum drop speed or a local maximum drop speed according to an embodiment;

[0087] FIG. 9 is a flow chart of searching a time point when a drop speed of a control rod cluster chops rapidly according to an embodiment; and FIG. 10 is a schematic diagram of a calculation and analysis result of drop time of a control rod cluster according to an embodiment.

[0088] Referring to FIG. 4, in an embodiment, a rod position measurement device 100 includes a rod position measurement cabinet 20 which provides excitation power supply to a rod position detector 10.

[0089] Different from an existing method where a voltage signal of a primary coil of a rod position detector is extracted and transmitted to a rod control device room for rod drop time measurement in a time-division switching manner according to different rod clusters during a test, in embodiments of the present disclosure, a rod drop time measurement and analysis module 21 is arranged (integrated) in a rod position measurement cabinet 20 with a rod drop time measurement and analysis function. The rod drop time measurement and analysis module 21 calculates and analyzes based on a primary coil voltage Up fed back by the rod position detector 10, measurement coil voltages Ua, Ub, Uc, Ud and Ue, and a rod drop reference signal DROPref introduced from a drive mechanism monitoring cabinet 50, to obtain a rod cluster drop waveform and a drop time of a control rod cluster.

[0090] The rod drop reference signal DROPref is obtained by adding holding coil current signals each of which is selected from each subgroup of control rods.

[0091] It should be noted that during measurement of the drop time of the control rod cluster, a reactor operator in a main control room lifts each group of control rods respectively, and after lifting to top of the reactor, the operator disconnects an excitation power supply of a corresponding rod position measurement channel in the rod position measurement cabinet 20, and disconnects a power supply of the corresponding subgroup in a rod control power distribution cabinet. Accordingly, a power supply disconnection signal is transmitted to the rod position measurement cabinet 20 through the rod drop reference signal DROPref. During this process, the rod drop time measurement and analysis module 21 automatically captures the rod drop signal, records and processes it, and analyzes and calculates the drop time of the control rod cluster.

[0092] Referring to FIGS. 5A, 5B and 6, a method for measuring drop time of a control rod cluster integrated with a rod position measurement device is provided, wherein the method is used to measure the drop time of each control rod cluster, and includes: S1, monitoring a voltage Ua of coils in Group A to capture a rod cluster drop signal; S2, searching a point (tmax, Vmax) with a maximum drop speed or with a local maximum drop speed; S3, retroactively calculating, from tmax, an end of a time period T4 when the control rod cluster starts to drop; S4, retroactively searching, from a minimum value point of a drop reference signal DROPref, a start of the time period T4 when the drop reference signal DROPref drops from a maximum value to 33% of the maximum value; S5, determining, from tmax forward, a time point t6 when a drop speed of the control rod cluster is lower than 0; S6, calculating an end of a time period T6 when the drop speed of the control rod cluster is 0; S7, searching an end of a time period T5 when the drop speed of the control rod cluster drops rapidly; S8, calculating a time point t7 when the drop speed returns to 0 after t6; S9, calculating a time point t8 when the drop speed returns to 0 after t7; S10, calculating a time point t9 when the drop speed returns to 0 after t8; and S11, obtaining an analysis result, and saving and outputting the analysis result in a form of file.

[0093] Optionally, referring to FIGS. 7A and 7B, S1 includes: S1.1, performing digital filtering on the voltage Ua of the coils in Group A to obtain a first filtered voltage; S1.2, transforming a waveform of the first filtered voltage into broken lines and removing outlier points on the broken lines; S1.3, calculating a first median sequence; S1.4, searching a first minimal value point P2 (tmin, Vmin) of the first median sequence; S1.5, searching backward, from the first minimal value point, a median point P1 with a value smaller than Vmin/2; S1.6, determining a point P0 where a line connecting the first minimal value point P2 and the median point P1 intersects with a 0-axis; and S1.7, if a slope of a line connecting P0 and P2, a time difference between P0 and P2, and an amplitude difference between P0 and P2 are within predetermined lined ranges respectively, determining that the control rod cluster starts to drop.

[0094] Optionally, referring to FIG. 8, S2 includes: S2.1, performing digital filtering on a voltage Up of a primary coil to obtain a second filtered voltage; S2.2, transforming a waveform of the second filtered voltage into broken lines and removing outlier points on the broken lines; S2.3, calculating a second median sequence; S2.4, searching among the second median sequence a point P1, wherein absolute values of the point P1 and preceding three points of the point P1 exceed 0.5; S2.5, if a value of P1 is negative, inverting the second median sequence; S2.6, searching backward, from P1, a point P0 with a value smaller than or equal to 0, and searching forward, from P1, a point P2 with a value smaller than or equal to 0; and S2.7, calculating a maximal value among a section between P0 and P2 to obtain Pmax (tmax, Vmax).

[0095] Optionally, referring to FIGS. 5A and 5B, S3 includes: retroactively searching, from tmax, a point P04 with an amplitude smaller than 0.4*Vmax, retroactively searching, from tmax, a point P02 with an amplitude smaller than 0.2*Vmax, and determining an end of the time period T4 where a line connecting P04 and P02 intersects with a 0-axis.

[0096] Optionally, S4 includes: obtaining a subsequence of a value sequence corresponding to the drop reference signal DROPref before tmax, determining a minimum value point and a maximum value point of the subsequence, and searching backward, from the minimum value point, a point with a value greater than 33% of a maximum value of the subsequence.

[0097] Optionally, S5 includes: searching, among the second median sequence and from tmax, a point with a value smaller than 0, and setting a time point of the point to be t6.

[0098] Optionally, S6 includes: determining a point where a line connecting a point corresponding to t6 and a point corresponding to (t6-1) inserts with the 0-axis as an end t6 of the time period T6.

[0099] Optionally, referring to FIGS. 9, 5A and 5B, S7 includes: S7.1, retroactively searching, from t6, a point P05 with an amplitude greater than 50% of Vmax; S7.2, retroactively searching, from t6, a point P075 with an amplitude greater than 75% of Vmax; S7.3, determining a horizontal line Line1 passing through Pmax (tmax, Vmax); S7.4, determining a straight line Line2 passing through P05 and P075; and S7.5, determining a point where Line1 intersects with Line2, wherein a time point corresponding to the point is an end of the time period T5.

[0100] Optionally, S11 includes: S11.1, calculating the time period T4 by subtracting the start of T4 from the end of T4, calculating the time period T5 by subtracting the end of T4 from the end of T5, and calculating the time period T6 by subtracting the end of T5 from the end of T6; S11.2, verifying that T4, T5, T6 are within a threshold range; S11.3, verifying positivity of t7, t8 and t9; and S11.4: saving and outputting calculation results in the form of file.

[0101] The calculation and analysis result of the drop time can be found in FIG. 10. Technical features such as specific type selection of the control rods in the present disclosure may be referred to exiting solutions. Specific structures, working principles, possible control methods and possible spatial arrangements of these technical features may adopt common selections in the art, which should not be regarded as an invention point of the present disclosure, and is not described in detail here.

[0102] It is still possible for those skilled in the art to modify technical solutions described in the foregoing embodiments, or to perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements and improvement made within the spirit and principles of the present disclosure should fall into the scope of the present disclosure.