Calculation and Decision-Making Methods for Evacuation Dose Rate Thresholds in Nuclear Power Plant Emergency Command Centers

Abstract

This invention belongs to the field of nuclear emergency technology, specifically relating to a method for calculating and deciding on the dose rate threshold for personnel evacuation in a nuclear power plant emergency command center. The method involves: calculating a conservative threshold: sorting all data in a typical accident scenario dose rate threshold set and selecting the minimum value, which is the conservative threshold applicable to any scenario; determining the current accident scenario: if the accident scenario is unclear, selecting the conservative threshold applicable to any scenario as the final threshold; if the accident scenario is clear, selecting the corresponding data from the typical accident scenario dose rate threshold set as the final threshold based on meteorological data and accident type; obtaining the readings of radiation monitoring instruments inside the emergency command center; if the readings are greater than or equal to the final threshold, providing a decision suggestion for the evacuation of personnel in the emergency command center. This invention effectively improves the rationality and timeliness of decision-making regarding corresponding response actions for personnel in the emergency command center during nuclear power plant accidents.

Description

Technical Field

[0001] This invention belongs to the field of nuclear emergency technology, specifically relating to a method for calculating and deciding on the evacuation dose rate threshold for personnel in a nuclear power plant emergency command center. Background Technology

[0002] The emergency command center of a nuclear power plant is the command center for implementing emergency response in the event of an accident at the nuclear power plant. It is also the assembly and workplace of certain emergency action groups (operational support, technical support, logistical support, security, etc.).

[0003] The "Emergency Preparedness and Response for Nuclear Power Plant Operators" (HAD002 / 01-2019) stipulates that nuclear power plant operators should evaluate the habitability of emergency facilities. It also requires emergency command centers to have appropriate measures in place to protect against hazards caused by serious accidents over extended periods, ensuring habitability. When considering accident scenarios involving the release of radioactive materials, habitability criteria should be determined based on the potential radiation dose to workers: during the established continuous emergency response period (generally 30 days), the effective dose received by workers should not exceed 50 mSv, and the thyroid equivalent dose should not exceed 500 mSv.

[0004] Habitability assessments of emergency command centers typically consider conservative meteorological conditions and typical design baseline and severe accidents to evaluate whether the radiation dose to staff exceeds habitability criteria. However, scenarios involving the superposition of extreme meteorological conditions and severe accidents, where radiation dose may exceed habitability criteria, have not been calculated or analyzed. This invention primarily addresses these extreme situations by providing a threshold for the internal environmental dose rate when an emergency command center fails to meet habitability criteria. This threshold guides the rapid evacuation of staff within the emergency command center, thereby effectively improving the rationality and timeliness of response decisions. Summary of the Invention

[0005] The purpose of this invention is to provide a method for calculating and deciding on the evacuation dose rate threshold for personnel in nuclear power plant emergency command centers, thereby solving the problem of habitability assessment for nuclear power plant emergency command centers. This method provides the corresponding environmental dose rate threshold within the emergency command center when the emergency command center cannot meet the habitability criteria in the context of a severe nuclear accident, and quickly provides decision-making suggestions based on this threshold. This effectively improves the rationality and timeliness of decision-making regarding corresponding response actions for personnel in the emergency command center during nuclear power plant accidents.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for calculating and deciding on the evacuation dose rate threshold for personnel in a nuclear power plant emergency command center, comprising the following steps: 1) Preparing meteorological data: classifying and categorizing various meteorological elements and combining them to form a meteorological data set;

[0008] 2) Prepare accident type and source term data: Select severe accidents to form a set of severe accident types. The set of severe accident types consists of multiple sets of accident and source term data. Each set of source term data includes the released nuclides and their release activities over time periods.

[0009] 3) Selecting a combination of meteorological and accident types: Select one meteorological data point from the meteorological data set and a set of accident source data points from the severe accident type set as the calculation input;

[0010] 4) Calculate dose and dose rate: Calculate the effective dose, thyroid dose and internal environmental dose rate for personnel in the emergency command center. The effective dose, thyroid dose and dose rate are all time-segmented numerical sequences.

[0011] 5) Habitability assessment: If the cumulative effective dose in the calculation result is greater than or equal to 50 mSv or the cumulative thyroid dose is greater than or equal to 500 mSv, then proceed to step 6); otherwise, end the calculation and return to step 3).

[0012] 6) Preliminary screening: Identify the first time segment index where the cumulative effective dose reaches 50 mSv or the cumulative thyroid dose reaches 500 mSv. Based on this, operate on the dose rate numerical sequence, remove all data after this index, and form the dose rate numerical sequence after preliminary screening.

[0013] 7) Secondary screening: Dose rate data below the minimum effective limit are removed to form the final dose rate value sequence after screening;

[0014] 8) Calculate and determine the dose rate threshold: Calculate the average value of the final filtered dose rate numerical sequence, that is, the dose rate threshold under the given combination of meteorological data and accident source data, and add the dose rate threshold to the typical accident scenario dose rate threshold set;

[0015] 9) Repeat steps 3) through 8) until all meteorological data and severe accident type combinations have been traversed;

[0016] 10) Calculate the conservative threshold: Sort all data in the dose rate threshold set of typical accident scenarios and take the minimum value. This value is the conservative threshold applicable to any scenario.

[0017] 11) Current accident scenario assessment: If the accident scenario is unclear, proceed to 12); if the accident scenario is clear, proceed to 13).

[0018] 12) When the accident scenario is unclear, select a conservative threshold applicable to any scenario as the final threshold;

[0019] 13) When the accident scenario is clear, select the corresponding data from the typical accident scenario dose rate threshold set as the final threshold based on meteorological data and accident type;

[0020] 14) Obtain the readings of radiation monitoring instruments inside the emergency command center. If the readings are greater than or equal to the final threshold, provide a decision recommendation for the evacuation of personnel from the emergency command center.

[0021] Prepare meteorological data: Classify and categorize various meteorological elements based on historical statistical data from nuclear power plants.

[0022] Prepare accident type and source term data: Select severe accidents based on the nuclear power plant's safety analysis report.

[0023] Calculate dose and dose rate: time segments are cumulative up to 30 days.

[0024] The beneficial effects achieved by this invention are as follows:

[0025] This method is mainly aimed at situations where the emergency command center cannot meet the habitability criteria in severe accident scenarios. It provides a threshold for the corresponding environmental dose rate within the emergency command center and quickly gives decision-making suggestions based on this, thereby effectively improving the rationality and timeliness of the decision-making for the corresponding response actions taken by the personnel in the emergency command center in the event of a nuclear power plant accident.

[0026] 1) The present invention provides a method for calculating the dose rate threshold for personnel evacuation in an emergency command center under nuclear power plant accident conditions, which can provide the corresponding environmental dose rate threshold when the emergency command center cannot meet the habitability criteria under severe accident conditions;

[0027] 2) The dose rate threshold for personnel evacuation in the emergency command center given by this invention includes dose rate thresholds for various typical accident scenarios, and can be applied to combinations of specific meteorological conditions and accident types;

[0028] 3) The dose rate threshold for personnel evacuation in the emergency command center given in this invention also includes a conservative dose rate threshold, which can be applied to any accident scenario;

[0029] 4) The present invention provides a decision-making method based on the dose rate threshold for personnel evacuation in an emergency command center, which can quickly provide decision-making suggestions for personnel evacuation in an emergency command center based on the readings of radiation monitoring instruments inside the emergency command center.

[0030] 5) The decision-making method of the present invention based on the dose rate threshold of personnel evacuation in the emergency command center can be applied to both unclear and clear accident scenarios. Attached Figure Description

[0031] Figure 1 Flowchart for calculating the dose rate threshold for personnel evacuation at the emergency command center of a nuclear power plant;

[0032] Figure 2 A flowchart for the decision-making process of the dose rate threshold for personnel evacuation at the emergency command center of a nuclear power plant. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0034] This invention includes a method for calculating the dose rate threshold for personnel evacuation in an emergency command center during a nuclear power plant accident, and a decision-making method based on the aforementioned threshold. It mainly includes the following steps (where 1-10 are the method for calculating the dose rate threshold for personnel evacuation in the emergency command center, and 11-14 are the decision-making method based on the aforementioned threshold):

[0035] (1) Preparing meteorological data: Based on historical statistical data of the nuclear power plant, various meteorological elements are classified and categorized, and combined to form a meteorological data set. The meteorological data set consists of multiple meteorological data points;

[0036] (2) Prepare accident type and source term data: Based on the safety analysis report of the nuclear power plant, select the main serious accidents to form a set of serious accident types. The set of serious accident types consists of multiple sets of accident and source term data, and each set of source term data includes the released nuclides and their release activities over time periods;

[0037] (3) Selecting a combination of meteorological and accident types: Select one meteorological data point from the meteorological data set and a set of accident source data points from the severe accident type set as the calculation input;

[0038] (4) Calculate dose and dose rate: Calculate the radiation dose (effective dose, thyroid dose) and internal environmental dose rate of personnel in the emergency command center. The radiation dose and dose rate are numerical sequences in time segments (cumulative up to 30 days).

[0039] (5) Residenceability determination: If the cumulative effective dose in the calculation result is greater than or equal to 50 mSv or the cumulative thyroid dose is greater than or equal to 500 mSv, then proceed to step (6); otherwise, end the calculation and return to step (3).

[0040] (6) Preliminary screening: Identify the first time segment index when the cumulative effective dose reaches 50 mSv or the cumulative thyroid dose reaches 500 mSv, and operate on the dose rate numerical sequence accordingly to remove all data after the index, forming the dose rate numerical sequence after preliminary screening.

[0041] (7) Secondary screening: Remove dose rate data that are less than the minimum effective limit to form the final dose rate value sequence after screening;

[0042] (8) Calculate and determine the dose rate threshold: Calculate the average value of the final filtered dose rate numerical sequence, that is, the dose rate threshold under the given combination of meteorological data and accident source data, and add the dose rate threshold to the typical accident scenario dose rate threshold set;

[0043] (9) Repeat steps (3) to (8) until all meteorological data and severe accident type combinations have been traversed;

[0044] (10) Calculate the conservative threshold: Sort all the data in the dose rate threshold set of typical accident scenarios and take the minimum value. This value is the conservative threshold applicable to any scenario.

[0045] (11) Current accident scenario judgment: If the accident scenario is unclear, proceed to step (12); if the accident scenario is clear, proceed to step (13).

[0046] (12) When the accident scenario is unclear, select a conservative threshold applicable to any scenario as the final threshold;

[0047] (13) When the accident scenario is clear, select the corresponding data from the typical accident scenario dose rate threshold set as the final threshold based on meteorological data and accident type;

[0048] (14) Obtain the readings of radiation monitoring instruments inside the emergency command center. If the readings are greater than or equal to the final threshold, provide a decision-making suggestion for the evacuation of personnel from the emergency command center.

[0049] Example: Calculation of dose rate threshold for personnel evacuation in emergency command center during nuclear power plant accident.

[0050] See appendix Figure 1 The calculation of the dose rate threshold for personnel evacuation in the emergency command center under nuclear power plant accident conditions in this embodiment mainly includes the following steps:

[0051] 1) Prepare meteorological data: Based on historical statistical data from the nuclear power plant, classify and categorize various meteorological elements, and combine them to form a meteorological data set. This meteorological data set consists of multiple meteorological data points;

[0052] 2) Prepare accident type and source term data: Based on the nuclear power plant's safety analysis report, select the main severe accidents to form a set of severe accident types. This set of severe accident types consists of multiple sets of accident and source term data, with each set of source term data including the released nuclides and their time-period release activity;

[0053] 3) Selecting a combination of meteorological and accident types: Select one meteorological data point from the meteorological data set and a set of accident source data points from the severe accident type set as the calculation input;

[0054] 4) Calculate dose and dose rate: Calculate the radiation dose (effective dose, thyroid dose) and internal environmental dose rate of personnel in the emergency command center. The radiation dose and dose rate are numerical sequences in time segments (cumulative up to 30 days).

[0055] 5) Residenceability determination: If the cumulative effective dose in the calculation result is greater than or equal to 50 mSv or the cumulative thyroid dose is greater than or equal to 500 mSv, then proceed to step (6); otherwise, end the calculation and return to step (3).

[0056] 6) Preliminary screening: Identify the first time segment index where the cumulative effective dose reaches 50 mSv or the cumulative thyroid dose reaches 500 mSv. Based on this, operate on the dose rate numerical sequence, remove all data after this index, and form the dose rate numerical sequence after preliminary screening.

[0057] 7) Secondary screening: Dose rate data below the minimum effective limit are removed to form the final dose rate value sequence after screening;

[0058] 8) Calculate and determine the dose rate threshold: Calculate the average value of the final filtered dose rate numerical sequence, that is, the dose rate threshold under the given combination of meteorological data and accident source data, and add the dose rate threshold to the typical accident scenario dose rate threshold set;

[0059] 9) Repeat steps (3) to (8) until all meteorological data and severe accident type combinations have been traversed; 10) Calculate the conservative threshold: Sort all data in the dose rate threshold set of typical accident scenarios and take the minimum value, which is the conservative threshold applicable to any scenario.

[0060] The example is based on the decision-making process of the evacuation dose rate threshold for personnel in the emergency command center during a nuclear power plant accident.

[0061] See appendix Figure 2 The decision-making method in this embodiment mainly relies on the appendix. Figure 1 The meteorological data set, severe accident type set, typical accident scenario dose rate threshold set, and conservative threshold applicable to any scenario generated in the calculation of the dose rate threshold for personnel evacuation in the emergency command center under the circumstances of a nuclear power plant accident are included in the following steps:

[0062] 1) Accident scenario judgment: If the accident scenario is unclear, proceed to step (2); if the accident scenario is clear, proceed to step (3).

[0063] 2) When the accident scenario is unclear, select a conservative threshold applicable to any scenario as the final threshold;

[0064] 3) When the accident scenario is clear, select the corresponding data from the typical accident scenario dose rate threshold set as the final threshold based on meteorological data and accident type;

[0065] 4) Obtain the readings of radiation monitoring instruments inside the emergency command center. If the readings are greater than or equal to the final threshold, provide a decision-making recommendation for the evacuation of personnel from the emergency command center.

Claims

1. A method for calculating and deciding the personnel evacuation dose rate threshold of an emergency command center of a nuclear power plant, characterized in that: The steps are as follows: 1) Prepare meteorological data: classify each meteorological element, and combine to form a meteorological data set; 2) Prepare accident type and source term data: select serious accidents to form a serious accident type set, which consists of multiple sets of accident and source term data, each set of source term data including released nuclides and their hourly release activity; 3) Select meteorological and accident type combinations: select one meteorological data from the meteorological data set and one set of accident source term data from the serious accident type set as the calculation input; 4) Calculate dose and dose rate: calculate the effective dose, thyroid dose and internal environment dose rate of the emergency command center personnel, all of which are time-segmented numerical sequences; 5) Habitable judgment: if the cumulative effective dose in the calculation result is greater than or equal to 50 mSv or the cumulative thyroid dose is greater than or equal to 500 mSv, go to step 6), otherwise end this calculation and return to step 3); 6) Preliminary screening: identify the first time segment index at which the cumulative effective dose reaches 50 mSv or the cumulative thyroid dose reaches 500 mSv, and operate on the dose rate numerical sequence accordingly, eliminating all data after the index to form a preliminary screened dose rate numerical sequence; 7) Secondary screening: eliminate dose rate data less than the minimum effective limit to form a final screened dose rate numerical sequence; 8) Calculate and determine the dose rate threshold: calculate the average of the final screened dose rate numerical sequence, which is the dose rate threshold under the given meteorological data and accident source term data combination, and add the dose rate threshold to the typical accident scenario dose rate threshold set; 9) Repeat steps 3) to 8) until all meteorological data and serious accident type combinations are completed; 10) Calculate the conservative threshold: sort all data in the typical accident scenario dose rate threshold set, and take the minimum value, which is the conservative threshold applicable to any scenario; 11) Current accident scenario judgment: if the accident scenario is unknown, go to 12), if the accident scenario is known, go to 13); 12) When the accident scenario is unknown, select the conservative threshold applicable to any scenario as the final threshold; 13) When the accident scenario is known, select the corresponding data from the typical accident scenario dose rate threshold set as the final threshold according to the meteorological data and accident type; 14) Obtain the reading of the emergency command center internal radiation monitoring instrument, and if the reading is greater than or equal to the final threshold, give a decision-making suggestion for the evacuation of the emergency command center personnel.

2. The method of claim 1, wherein the method further comprises: determining a dose rate threshold for personnel evacuation at the emergency command center based on the dose rate threshold for personnel evacuation at the nuclear power plant. Prepare meteorological data: classify each meteorological element according to the historical statistical data of the nuclear power plant.

3. The method of claim 1, wherein the method further comprises: determining a dose rate threshold for personnel evacuation at the emergency command center based on the dose rate threshold for personnel evacuation at the nuclear power plant. Prepare accident type and source term data: select serious accidents according to the safety analysis report of the nuclear power plant.

4. The method of claim 1, wherein the method further comprises: determining a dose rate threshold for personnel evacuation at the emergency command center based on the dose rate threshold for personnel evacuation at the nuclear power plant. Calculate dose and dose rate: time segmentation is cumulative to 30 days.

Images