A sodium-cooled fast reactor core damage evaluation method, storage medium and system

Abstract

The present application relates to a kind of sodium-cooled fast reactor core damage evaluation method, comprising the following steps: evaluation parameter monitoring is carried out, and the core state is judged according to the evaluation parameter read;The evaluation of fuel cladding gas tightness damage fraction is carried out, and the evaluation result of fuel cladding gas tightness damage is verified reasonably;The evaluation of fuel cladding damage fraction is carried out, and the evaluation result of fuel cladding damage is verified reasonably.The present application also provides a kind of storage medium and sodium-cooled fast reactor core damage evaluation system, using sodium-cooled fast reactor core damage evaluation method, storage medium and system can qualitatively judge the damage state of core and quantitatively evaluate the damage degree of core.

Description

Technical Field

[0001] This invention belongs to the field of nuclear and radiation emergency response, and specifically relates to a method, storage medium and system for evaluating damage to the core of a sodium-cooled fast reactor. Background Technology

[0002] Because the results of accident source term estimation and dose prediction models are unavailable in early accident response strategies, the International Atomic Energy Agency (IAEA) first proposed a new concept in 2014 that guides protective actions directly based on the results of fuel damage assessment, without requiring source term estimation and dose diffusion simulation. Therefore, core damage assessment is extremely important for nuclear accident emergency response at nuclear power plants.

[0003] Currently, there are no publicly available literature, either domestic or international, on core damage assessment methods for sodium-cooled fast reactors.

[0004] Therefore, a method is needed that can qualitatively determine the damage state of the reactor core and quantitatively evaluate the degree of damage to the reactor core. Summary of the Invention

[0005] In view of the deficiencies in the existing technology, the purpose of this invention is to provide a method, storage medium and system for evaluating damage to the core of a sodium-cooled fast reactor, so as to qualitatively determine the damage status of the core and quantitatively evaluate the degree of damage to the core.

[0006] To achieve the above objectives, the technical solution adopted by this invention is: a method for evaluating core damage in a sodium-cooled fast reactor, comprising the following steps: monitoring evaluation parameters and judging the core condition based on the read evaluation parameters; assessing the proportion of fuel cladding airtightness failure and verifying the rationality of the fuel cladding airtightness failure evaluation results; and assessing the proportion of fuel cladding failure and verifying the rationality of the fuel cladding failure evaluation results.

[0007] Furthermore, the core condition includes undamaged core, damaged fuel cladding, and damaged fuel cladding.

[0008] Furthermore, the evaluation parameters include delayed neutron count rate, core exit sodium temperature, radioactivity in the covering gas cavity, main vessel liquid level, main vessel covering gas pressure, primary loop hot-end temperature, source range count rate monitoring reading, and main vessel wall temperature. Among these, delayed neutron count rate, core exit sodium temperature, and covering gas cavity radioactivity are used to determine the core damage state and damage fraction; main vessel liquid level, main vessel covering gas pressure, primary loop hot-end temperature, source range count rate monitoring reading, and main vessel wall temperature are used to evaluate the reasonableness of the core damage evaluation results.

[0009] Further, the core state is determined based on: when the relationship of the readings satisfies: the reading of the delayed neutron monitoring system < SN1, the core outlet sodium temperature < CET1, and the radioactivity in the cover gas cavity < MVRM1, there is no core damage; when the reading of the delayed neutron monitoring system < SN1, the core outlet sodium temperature < CET2, the radioactivity in the cover gas cavity < MVRM2, and (CET1 ≤ the core outlet sodium temperature or MVRM1 ≤ the radioactivity in the cover gas cavity), the evaluation of the airtightness damage fraction of the fuel cladding is performed; when the reading of the delayed neutron monitoring system ≥ SN1, or the core outlet sodium temperature ≥ CET2, or the radioactivity in the cover gas cavity ≥ MVRM2, the evaluation of the fuel cladding damage fraction is performed; wherein, SN1 represents the upper limit of the reading of the delayed neutron monitoring system for fuel damage under normal working conditions, that is, the monitoring value corresponding to 0.1% fuel cladding damage; CET1 indicates that when the temperature is higher than this value, airtightness damage of the cladding may occur in the core; CET2 indicates that when the temperature is higher than this value, fuel cladding damage may occur; MVRM1 represents the radioactivity corresponding to the release of fission products from 0.1% cladding airtightness damage to the cover gas cavity; MVRM2 represents the radioactivity corresponding to the release of 1% fuel cladding damage to the cover gas cavity.

[0010] Further, the evaluation of the airtightness damage fraction of the fuel cladding includes: evaluating the airtightness damage fraction of the fuel cladding based on the core outlet sodium temperature and evaluating the airtightness damage fraction of the fuel cladding based on the radioactivity in the cover gas cavity.

[0011] Further, performing rationality verification on the evaluation result of fuel cladding airtightness damage includes: the reading of the delayed neutron monitoring system < SN1; MVL2 < main vessel liquid level ≤ MVL1; the primary loop hot leg temperature > RTD1; the source range count rate monitoring reading > SRM1; the main vessel wall temperature < WVT1; using the following formula:

[0012]

[0013] The relative deviation between the evaluation results of the two evaluation parameters is < 50%.

[0014] Further, the evaluation of the fuel cladding damage fraction includes evaluating the fuel cladding damage fraction based on the reading of the delayed neutron monitoring system, evaluating the fuel cladding damage fraction based on the core outlet sodium temperature, and evaluating the fuel cladding damage fraction based on the radioactivity in the cover gas cavity.

[0015] Further, performing rationality verification on the fuel cladding damage evaluation result includes: the main vessel liquid level ≤ MVL2; using the following formula:

[0016]

[0017] The relative error of the evaluation results based on two evaluation parameters—core outlet sodium temperature and covered gas cavity radioactivity—is <50%.

[0018] Use the following formula:

[0019]

[0020] The relative error of the evaluation results based on two evaluation parameters—core outlet sodium temperature and delayed neutron monitoring system readings—is <25%.

[0021] The present invention also provides a storage medium storing a computer program thereon, which, when executed by a processor, implements a method for evaluating core damage in a sodium-cooled fast reactor.

[0022] The present invention also provides a sodium-cooled fast reactor core damage assessment system, comprising: a parameter monitoring module for monitoring and reading parameters to determine the core condition based on the read parameters; a fuel cladding airtightness damage assessment module for assessing the proportion of fuel cladding airtightness damage and verifying the rationality of the fuel cladding airtightness damage assessment results; and a fuel cladding damage assessment module for assessing the proportion of fuel cladding damage and verifying the rationality of the fuel cladding damage assessment results.

[0023] The advantages of this invention are: by using online monitoring instrument readings, the damage status of the reactor core can be qualitatively determined and the degree of damage of the reactor core can be quantitatively evaluated, thereby realizing the evaluation of the degree of damage of the sodium-cooled fast reactor core. Attached Figure Description

[0024] Figure 1 This is a flowchart of the steps in the sodium-cooled fast reactor core damage evaluation method of the present invention;

[0025] Figure 2 This is a schematic diagram illustrating the principle of a sodium-cooled fast reactor core damage evaluation method according to the present invention. Detailed Implementation

[0026] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1-2 As shown, this method, based on the characteristics of the nuclear island monitoring equipment of the 600MW demonstration fast reactor project, proposes a damage assessment method for the core of a sodium-cooled fast reactor under nuclear emergency conditions, including the following steps:

[0028] S1, monitor the evaluation parameters and determine the core status based on the read evaluation parameters;

[0029] Specifically, there are three types of core damage states: no core damage (0.1% fuel cladding airtightness failure), fuel cladding airtightness failure (release of fission products between fuel rods), and fuel cladding failure (release of fission products from fuel blocks; 100% failure means 100% core meltdown).

[0030] The evaluation parameters for the monitoring instrument readings mainly include: (1) delayed neutron count rate (SN); (2) core outlet sodium temperature (CET); (3) radioactivity of the covering gas cavity (MVRM); (4) main vessel liquid level (MVL); (5) main vessel covering gas pressure (MVP); (6) primary loop hot end temperature (RTD); (7) source range count rate monitoring reading (SRM); (8) main vessel wall temperature (WVT); among which, (1) to (3) are the main basis for determining the core damage state and damage share, that is, used to determine the core damage state and damage share, while (4) to (8) are used to evaluate the rationality of the core damage evaluation results, that is, used to evaluate the rationality of the core damage evaluation results.

[0031] It should be noted that (1) Delayed neutron count rate (SN): To establish the relationship between the delayed neutron monitoring system reading (SN) and the core damage state, the setpoint SN1 needs to be determined. SN1 represents the upper limit of the delayed neutron monitoring system reading under normal operating conditions, that is, the monitoring value corresponding to 0.1% fuel cladding damage.

[0032] (2) Core exit sodium temperature (CET):

[0033] To establish the relationship between CET and core damage state, the setpoints CET1 and CET2 need to be determined. CET1 indicates that above this temperature, the core may experience cladding hermeticity failure; CET2 indicates that above this temperature, the fuel cladding may fail.

[0034] (3) Covered cavity radioactivity (MVRM): Based on the relationship between covered cavity radioactivity (MVRM) and core damage state, the setpoints to be determined are MVRM1, MVRM2, MVRM3, and MVRM4. MVRM1 represents the radioactivity corresponding to 0.1% of cladding gastightness failure fission products released into the covered cavity; MVRM2 represents the radioactivity corresponding to 1% of fuel cladding failure fission products released into the covered cavity; MVRM3 represents the radioactivity corresponding to 100% of cladding gastightness failure fission products released into the covered cavity; and MVRM4 represents the radioactivity corresponding to 100% of fuel cladding failure fission products released into the covered cavity.

[0035] (4) Main container level (MVL):

[0036] MVL can identify the type of core damage, but cannot perform quantitative analysis. To establish the relationship between MVL and core damage states, the setpoints to be determined are MVL1 and MVL2. MVL1 is the alarm liquid level of the main vessel; when the liquid level is lower than this level, the airtightness of the fuel cladding may be damaged. MVL2 represents the main vessel liquid level corresponding to the upper conversion region of the fuel. When the liquid level is lower than this level, the fissile region of the core is exposed and the fuel temperature rises.

[0037] (5) Main Vessel Cover Gas Pressure (MVP): MVP cannot determine the core damage state, but it can assist in determining the radioactivity activity in the cover gas cavity by correcting the radioactivity activity of the cover gas. The setpoint to be determined for MVP is MVP1. MVP1 represents the actuation pressure of the liquid seal in the overpressure protection system of the main vessel.

[0038] (6) Primary Loop Hot Leg Temperature (RTD): RTD can only qualitatively determine the core damage state, and cannot quantitatively determine the core damage state. The setpoint to be determined for RTD is RTD1. RTD1 indicates that the core may be exposed and the fuel temperature will rise.

[0039] (7) Source Range Count Rate Monitoring Reading (SRM):

[0040] SRM can qualitatively determine the core damage state, but cannot give the core damage fraction. The setpoint to be determined for SRM is SRM1. SRM1 indicates that when the reading is higher than this value, the core may be exposed.

[0041] (8) Main Vessel Wall Temperature (WVT): WVT can qualitatively determine the core damage state, but cannot give the core damage fraction. The setpoint to be determined for WVT is WVT1. WVT1 represents the main vessel wall temperature when the structural integrity of the main vessel is challenged, indicating severe damage to the fuel cladding.

[0042] When the relationship between the readings satisfies: Delayed Neutron Monitoring System Reading (SN) < SN1, Core Exit Sodium Temperature (CET) < CET1, and Cover Gas Cavity Radioactivity Activity (MVRM) < MVRM1, the core is undamaged and parameter monitoring shall be continued.

[0043] When Delayed Neutron Monitoring System Reading (SN) < SN1, Core Exit Sodium Temperature (CET) < CET2, Cover Gas Cavity Radioactivity Activity (MVRM) < MVRM2, and (CET1 ≤ Core Exit Sodium Temperature (CET) or MVRM1 ≤ Cover Gas Cavity Radioactivity Activity (MVRM)), airtight damage of fuel cladding may occur, and the evaluation shall proceed to the assessment of fuel cladding airtight damage fraction.

[0044] When the reading (SN) of the delayed neutron monitoring system satisfies SN≥SN1, or the core exit sodium temperature (CET) satisfies CET≥CET2, or the radioactivity activity (MVRM) of the cover gas plenum satisfies MVRM≥MVRM2, fuel cladding damage may have occurred, and the process proceeds to the evaluation of fuel cladding damage fraction for assessment.

[0045] S2, evaluating the airtight damage fraction of fuel cladding, and performing rationality verification on the evaluation result of fuel cladding airtight damage;

[0046] Specifically, according to the readings of the core, when the readings satisfy that fuel cladding airtight damage may occur, the evaluation of the fuel cladding airtight damage fraction is performed.

[0047] The evaluation of the fuel cladding airtight damage fraction includes: evaluating the fuel cladding airtight damage fraction based on core exit sodium temperature (CET) and evaluating the fuel cladding airtight damage fraction based on cover gas plenum radioactivity activity (MVRM).

[0048] Wherein, the calculation formula for evaluating the fuel cladding airtight damage fraction based on core exit sodium temperature (CET) is:

[0049]

[0050] The calculation formula for evaluating the fuel cladding airtight damage fraction based on cover gas plenum radioactivity activity (MVRM) is:

[0051]

[0052] Under accident conditions, there is a considerable amount of sodium vapor in the cover gas plenum, the 22 Na and 24 Na will affect the radioactivity activity of the gas, and the influence of 22 Na and 24 Na and normal working conditions on radioactivity activity is counteracted through MVRM3-MVRM1.

[0053] 1) When MVP<MVP1:

[0054] Ex-core radioactivity activity(t)=MVRM(t+10min)×λ1+HCM(t)+CRM(t)

[0055] 2) When MVP≥MVP1:

[0056] Ex-core radioactivity activity(t)=MVRM(t+10min)×λ2+HCM(t)+CRM(t)

[0057] λ1 is a correction factor. After the release of radioactive material, some of it diffuses into the compensation container with the covering gas. Therefore, the dilution of radioactive material in the covering gas cavity by the compensation container needs to be considered. λ2 is another correction factor. After the main container overpressure protection system activates, in addition to considering the dilution by the compensation container, some radioactive material is discharged into the containment tank via the liquid sealer with the main container's covering gas. Specifically, this value represents the ratio of the amount of gas entering the containment tank to the total amount of covering gas. Therefore, the radioactivity of the main container's covering gas needs to be corrected. Since the covering gas detector detects a 10-minute delay, its data reflects the radioactivity up to 10 minutes prior.

[0058] After evaluating the fuel cladding airtightness failure percentage based on core outlet sodium temperature (CET) and mulch cavity radioactivity (MVRM), the evaluation results need to be validated for reasonableness to determine whether the relevant parameters are consistent with the accident situation. The specific criteria for this validation are as follows:

[0059] 1) Readings from the delayed neutron monitoring system <SN1;

[0060] 2) MVL2 < Main container level ≤ MVL1;

[0061] 3) The hot end temperature of the primary loop is greater than RTD1;

[0062] 4) Source range count rate monitoring reading > SRM1;

[0063] 5) Main container wall temperature <WVT1;

[0064] 6) Use the following formula to calculate the relative deviation of the evaluation results for the two evaluation parameters, which should be less than 50%:

[0065]

[0066] That is, the evaluation result is reasonable when the calculation result is less than 50%.

[0067] S3, assess the proportion of fuel cladding damage and verify the rationality of the assessment results of fuel cladding damage;

[0068] Specifically, based on the core readings, when the readings indicate a possible fuel cladding failure, an assessment of the fuel cladding failure percentage is conducted. This assessment includes: evaluating the fuel cladding failure percentage based on delayed neutron monitoring system readings (SN), evaluating the fuel cladding failure percentage based on core outlet sodium temperature (CET), and evaluating the fuel cladding failure percentage based on the radioactivity of the covered gas cavity (MVRM).

[0069] Wherein, the fuel cladding failure fraction is evaluated based on the reading (SN) of the delayed neutron monitoring system, and the formula is:

[0070]

[0071] The fuel cladding failure fraction is evaluated based on the core outlet sodium temperature (CET), and the formula is:

[0072]

[0073] The fuel cladding failure fraction is evaluated based on the radioactivity activity (MVRM) of the cover gas cavity, and the formula is:

[0074]

[0075] Under accident conditions, a considerable amount of sodium vapor exists in the cover gas cavity, and the 22 Na and 24 Na will affect the radioactivity activity of the gas, and the influence of 22 Na and 24 Na as well as radiation under normal working conditions is offset by (MVRM4-MVRM2).

[0076] 1) When MVP<MVP1:

[0077] Ex-core radioactivity activity(t) =

[0078] MVRM(t+10min)×λ1+HCM(t)+CRM(t)

[0079] 2) When MVP≥MVP1:

[0080] Ex-core radioactivity activity(t) =

[0081] MVRM(t+10min)×λ2+HCM(t)+CRM(t)

[0082] Wherein, λ1 is a correction factor. After the radioactive substance is released, part of the radioactive substance will diffuse into the compensation vessel along with the cover gas, therefore, it is necessary to consider the dilution of radioactive substances in the cover gas cavity by the compensation vessel; λ2 is a correction factor. After the main vessel overpressure protection system acts, in addition to considering the dilution problem of the compensation vessel, since part of the radioactive substance is discharged to the containment tank through the liquid sealer along with the cover gas of the main vessel, and its specific value is the ratio of the gas amount entering the containment tank to the total amount of cover gas, it is therefore necessary to correct the radioactivity of the cover gas of the main vessel. Since the detection by the cover gas detector has a delay of 10 minutes, the data reflects the radioactivity activity of 10 minutes ago.

[0083] After evaluating the fuel cladding damage fraction using delayed neutron monitoring system readings (SN), core outlet sodium temperature (CET), and mulch cavity radioactivity (MVRM), the evaluation results need to be validated for reasonableness to determine whether the relevant parameters are consistent with the accident situation. The specific criteria for validation are as follows:

[0084] 1) Main container liquid level ≤ MVL2;

[0085] 2) Using the following formula, the relative error of the evaluation results based on two evaluation parameters—core outlet sodium temperature and overlying gas cavity radioactivity—is <50%:

[0086]

[0087] Using the following formula, the relative error of the evaluation results based on two evaluation parameters—core outlet sodium temperature and delayed neutron monitoring system readings—is <25%:

[0088]

[0089] That is, if the relative error of the evaluation results based on the two evaluation parameters of core outlet sodium temperature and the radioactivity of the covered gas cavity is less than 50%, and the relative error of the evaluation results based on the two evaluation parameters of core outlet sodium temperature and the reading of the delayed neutron monitoring system is less than 25%, then the evaluation results are reasonable.

[0090] It is understandable that the evaluation results include the core damage type and its corresponding damage share, with the damage share expressed as a percentage (%).

[0091] The present invention also provides a storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of a method for evaluating damage to a sodium-cooled fast reactor core.

[0092] It should be noted that the storage medium shown in this application can be a computer-readable signal medium or a storage medium, or any combination of the two. The storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or any combination thereof. More specific examples of the storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this application, the storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. In this application, the storage medium can include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The storage medium may also be any computer-readable medium other than a storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, system, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0093] The present invention also provides a sodium-cooled fast reactor core damage evaluation system, comprising:

[0094] The parameter monitoring module is used to monitor and read parameters in order to determine the core status based on the read parameters.

[0095] The fuel cladding airtightness damage assessment module is used to evaluate the proportion of fuel cladding airtightness damage and to verify the rationality of the fuel cladding airtightness damage assessment results.

[0096] The fuel cladding damage assessment module is used to evaluate the proportion of fuel cladding damage and to verify the reasonableness of the assessment results.

[0097] As can be seen from the above embodiments, the beneficial effects of the present invention are as follows: by using online monitoring instrument readings, the damage state of the reactor core can be qualitatively determined and the degree of damage of the reactor core can be quantitatively evaluated, thereby realizing the evaluation of the degree of damage of the sodium-cooled fast reactor core.

[0098] The system described in this invention is not limited to the embodiments described in the specific implementation. Other implementation methods derived by those skilled in the art based on the technical solution of this invention also fall within the scope of technical innovation of this invention.

Claims

1. A method for evaluating core damage in a sodium-cooled fast reactor, characterized in that, Comprising: monitoring evaluation parameters, and judging core state according to the read evaluation parameters; evaluating the airtightness damage fraction of fuel cladding, and performing rationality verification on the evaluation result of fuel cladding airtightness damage; evaluating the fuel cladding damage fraction, and performing rationality verification on the evaluation result of fuel cladding damage; the core states include undamaged core, fuel cladding airtightness damage and fuel cladding damage; the evaluation parameters include delayed neutron counting rate, core outlet sodium temperature, radioactivity activity in the cover gas cavity, main vessel liquid level, main vessel cover gas pressure, primary circuit hot leg temperature, source range counting rate monitoring reading and main vessel wall temperature; wherein, the delayed neutron counting rate, the core outlet sodium temperature and the radioactivity activity in the cover gas cavity are used to determine the core damage state and damage fraction; the main vessel liquid level, the main vessel cover gas pressure, the primary circuit hot leg temperature, the source range counting rate monitoring reading and the main vessel wall temperature are used for rationality evaluation of the core damage evaluation result; the judgment basis for the core state is that when the relationship of the readings satisfies: delayed neutron monitoring system reading < SN1, the core outlet sodium temperature < CET1, and the radioactivity activity in the cover gas cavity < MVRM1, the core is undamaged; when the delayed neutron monitoring system reading < SN1, the core outlet sodium temperature < CET2, the radioactivity activity in the cover gas cavity < MVRM2, and "CET1 ≤ the core outlet sodium temperature or MVRM1 ≤ the radioactivity activity in the cover gas cavity", evaluating the airtightness damage fraction of fuel cladding; when the delayed neutron monitoring system reading ≥ SN1, or the core outlet sodium temperature ≥ CET2, or the radioactivity activity in the cover gas cavity ≥ MVRM2, evaluating the fuel cladding damage fraction; wherein, SN1 represents the upper limit of the reading of the delayed neutron monitoring system for fuel damage under normal working conditions, that is, the monitoring value corresponding to 0.1% fuel cladding damage; CET1 represents that when the temperature is higher than this value, cladding airtightness damage may occur in the core; CET2 represents that when the temperature is higher than this value, fuel cladding damage may occur; MVRM1 represents the radioactivity activity corresponding to fission products released from 0.1% cladding airtightness damage into the cover gas cavity; MVRM2 represents the radioactivity activity corresponding to 1% fuel cladding damage released into the cover gas cavity.

2. A sodium-cooled fast reactor core damage evaluation method according to claim 1, characterized in that: the evaluation of the fuel cladding airtightness damage fraction comprises evaluating the fuel cladding airtightness damage fraction based on core outlet sodium temperature and evaluating the fuel cladding airtightness damage fraction based on radioactivity activity in the cover gas cavity.

3. A sodium-cooled fast reactor core damage evaluation method according to claim 2, characterized in that: performing rationality verification on the evaluation result of fuel cladding airtightness damage comprises: delayed neutron monitoring system reading < SN1; MVL2 < main vessel liquid level ≤ MVL1; primary circuit hot leg temperature > RTD1; source range counting rate monitoring reading > SRM1; main vessel wall temperature < WVT1; using the following formula: the relative deviation of evaluation results obtained by two types of evaluation parameters is less than 50%; wherein MVRM3 indicates the radioactivity corresponding to the release of fission products from 100% cladding gas-tightness failure into the covered gas cavity.

4. The method for evaluating core damage in a sodium-cooled fast reactor as described in claim 1, characterized in that: The assessment of the fuel cladding damage share includes evaluating the fuel cladding damage share based on delayed neutron monitoring system readings, evaluating the fuel cladding damage share based on core outlet sodium temperature, and evaluating the fuel cladding damage share based on the radioactivity of the covering gas cavity.

5. The sodium-cooled fast reactor core damage evaluation method as described in claim 4, characterized in that: The rationality verification of the fuel cladding damage assessment results includes: Main container liquid level ≤ MVL2; Use the following formula: ; The relative error of the evaluation results based on two evaluation parameters—core outlet sodium temperature and coverage gas cavity radioactivity—is <50%. Use the following formula: The relative error of the evaluation results based on two evaluation parameters—core outlet sodium temperature and delayed neutron monitoring system readings—is <25%. in 。 6. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the sodium-cooled fast reactor core damage evaluation method according to any one of claims 1 to 5.

7. A sodium-cooled fast reactor core damage evaluation system, characterized in that, A method for evaluating core damage of a sodium-cooled fast reactor as described in any one of claims 1 to 5, comprising: The parameter monitoring module is used to monitor and read parameters in order to determine the core status based on the read parameters. The fuel cladding airtightness damage assessment module is used to evaluate the proportion of fuel cladding airtightness damage and to verify the rationality of the fuel cladding airtightness damage assessment results. The fuel cladding damage assessment module is used to evaluate the proportion of fuel cladding damage and to verify the reasonableness of the assessment results.

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