Calculation method for deposition and shedding of corrosion activation product of primary loop of nuclear power plant

Abstract

The invention belongs to the technical field of pressurized water reactor nuclear power plant radiochemistry, and particularly relates to a nuclear power plant primary loop corrosion activation product deposition and shedding calculation method which comprises the following steps: step 1, determining a purification state of a primary loop main system during a determination period; 2, measuring the activity before purification and the activity after purification of radionuclide of a primary loop main system; 3, calculating the purification efficiency of the radionuclide; 4, measuring the actual value of the nuclide of the main system; 5, calculating a theoretical value of the nuclide of the main system; and 6, calculating the net deposition rate or net shedding rate of the activated corrosion product in the main system. The method can quantify the deposition and falling state of the activated corrosion product in the primary loop, more accurately reflect the real condition, and provide effective data support for chemical control, thereby further reducing the generation of source items of the primary loop of the nuclear power plant, and improving the reliability of the nuclear power plant. The method is suitable for calculation of deposition and shedding of corrosion activation products in a primary loop purification dynamic change state.

Description

Technical Field

[0001] The invention belongs to the technical field of radioactive chemistry of pressurized water reactor nuclear power plants, and in particular relates to a calculation method for the deposition and shedding of corrosion activation products in a primary loop of a nuclear power plant. Background Art

[0002] Stainless steel and various alloys are the main equipment materials used in the primary circuit of nuclear power plants. As the reaction proceeds, corrosion will inevitably occur during operation. The corrosion products move and migrate to produce activated corrosion products after the core is activated. The release, activation, and deposition of corrosion products will lead to a high radiation dose in the reactor, especially the production of 58Co and 60Co during overhaul, which is not conducive to the control of radiation doses for professional workers. At the same time, these activated corrosion products are distributed in the entire primary circuit in a dynamic flow of "precipitation-dissolution-deposition", and the primary circuit is always in a dynamic purification bed purification process, which has caused certain difficulties in the migration and control research of chemical corrosion products in nuclear power plants.

[0003] At present, there are no publicly published papers, patents or standards to quantitatively calculate the deposition and shedding state of corrosion activation products in a dynamic loop. Therefore, it is impossible to accurately explore the deposition and shedding state of activated corrosion products in a loop within a certain period of time. Summary of the invention

[0004] The purpose of the present invention is to provide a calculation method for the deposition and shedding of corrosion activation products in a primary circuit of a nuclear power plant. The method can quantify the deposition and shedding state of activated corrosion products in the primary circuit, more accurately reflect the real situation, and provide effective data support for chemical control, thereby further reducing the generation of primary circuit source terms in the nuclear power plant. The method is suitable for the calculation of deposition and shedding of corrosion activation products under the dynamic change state of primary circuit purification.

[0005] The technical solution to achieve the purpose of the present invention is:

[0006] A method for calculating the deposition and shedding of corrosion activation products in a primary circuit of a nuclear power plant, the method comprising:

[0007] Step 1, determine the purification status of the primary system of the primary circuit during the measurement period;

[0008] Step 2, measuring the activity of radionuclides in the primary system of the primary loop before purification and after purification;

[0009] Step 3, calculating the purification efficiency of radionuclides;

[0010] Step 4, measuring the actual value of the nuclide of the main system;

[0011] Step 5, calculate the theoretical value of nuclides in the main system;

[0012] Step 6: Calculate the net deposition rate or net shedding rate of activated corrosion products in the main system.

[0013] The purification status of the primary-loop main system during the measurement in step 1 includes: the water volume of the primary-loop main system, the purification flow rate of the purification bed of the primary-loop main system, and the purification efficiency of the purification bed of the primary-loop main system.

[0014] The sampling points for measuring the activity of radionuclides before and after purification in step 2 are chemical sampling points downstream of the RCV purification bed.

[0015] The calculation formula for the purification efficiency of radionuclides in step 3 is:

[0016] E = (activity before purification - activity after purification) / activity before purification

[0017] Where E is the purification efficiency of radionuclides.

[0018] The sampling point for measuring the actual value of the nuclide of the main system in step 4 is the main system 3-ring chemical sampling point.

[0019] The method for measuring the actual value of the nuclide of the main system in step 4 is to use a high-purity germanium multi-channel gamma spectrometer to measure the radioactive nuclide.

[0020] The theoretical value calculation formula of the nuclide of the main system in step 5 is:

[0021]

[0022] in,

[0023] h: purification bed time;

[0024] L: water volume of the main system;

[0025] H: purification flow;

[0026] E: purification efficiency of the purification bed;

[0027] C2: When purification starts, the main system actually detects the nuclide value;

[0028] C1: Theoretical target nuclide value of the main system after purification for h hours.

[0029] The step 6 is specifically as follows: comparing the deviation between the actual value and theoretical value of the nuclides in the main system to determine whether the corrosion activation products in the main system are in a net deposition or net shedding state; and calculating the net deposition rate or net shedding rate of the corrosion activation products in the main system according to the actual value and theoretical value of the nuclides in the system.

[0030] In step 6, after purification, if the actual detected nuclide value of the main system is greater than the theoretical target nuclide value of the main system, it indicates that the shedding rate at this stage is greater than the deposition rate, and it is determined that the activated corrosion products in the main system are in a net shedding state. The net shedding rate of the corrosion activation products in the main system is calculated, and the calculation formula is as follows:

[0031]

[0032] in,

[0033] A1: Net shedding rate of corrosion activation products;

[0034] h: purification bed time;

[0035] C1: Theoretical target nuclide value of the main system after purification for h hours;

[0036] C3: After purification for h hours, the main system actually detects the nuclide value.

[0037] In step 6, after purification, if the theoretical target nuclide value of the main system is greater than the actual detected nuclide value of the main system, it indicates that the deposition rate at this stage is greater than the shedding rate, and it is determined that the activated corrosion products in the main system are in a net deposition state. The net deposition rate of the corrosion activation products in the main system is calculated, and the calculation formula is as follows:

[0038]

[0039] in,

[0040] A2: Net deposition rate of corrosion activation products;

[0041] h: purification bed time;

[0042] C1: Theoretical target nuclide of the main system after purification for h hours;

[0043] C3: After purification for h hours, the main system actually detects the nuclides.

[0044] The beneficial technical effects of the present invention are:

[0045] 1. The present invention provides a calculation method for the deposition and shedding of corrosion activation products in the primary circuit of a nuclear power plant, which ensures the quantitative and accurate evaluation of the deposition and shedding of corrosion products under the dynamic purification flow of the system;

[0046] 2. The present invention provides a calculation method for the deposition and shedding of corrosion activation products in the primary circuit of a nuclear power plant, which provides reliable data guidance for the migration and control research of activated corrosion products through quantitative deposition and shedding data;

[0047] 3. The present invention provides a calculation method for the deposition and shedding of corrosion activation products in a nuclear power plant primary circuit, which is simple to operate, highly applicable, and can be widely promoted and used. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The present invention provides a flow chart of a method for calculating the deposition and shedding of corrosion activation products in a primary circuit of a nuclear power plant. DETAILED DESCRIPTION

[0049] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0050] The present invention provides a method for calculating the deposition and shedding of corrosion activation products in a primary circuit of a nuclear power plant, which specifically comprises the following steps:

[0051] Step 1: Determine the purification status of the primary system during the measurement period

[0052] During the measurement period, the water volume of the primary circuit main system remains stable, and the water volume of the primary circuit main system is measured;

[0053] During the measurement period, the purification flow of the purification bed of the primary system of the primary circuit remains stable, and the purification flow of the purification bed of the primary system of the primary circuit is measured;

[0054] During the measurement period, the purification efficiency of the purification bed of the primary circuit main system remains stable, and the purification efficiency of the purification bed of the primary circuit main system is measured.

[0055] Step 2: Measure the activity of radionuclides in the primary system of the primary circuit before and after purification

[0056] The sampling points for measuring the activity of radionuclides before and after purification are the chemical sampling points downstream of the RCV purification bed.

[0057] Step 3: Calculate the purification efficiency E of radionuclides

[0058] The purification efficiency E of radionuclides represents the purification ability of the resin to the nuclides, and the calculation formula is:

[0059] E = (activity before purification - activity after purification) / activity before purification Formula (1)

[0060] Step 4: Measure the actual value of the nuclide in the main system

[0061] The sampling points for measuring the actual nuclides of the main system are the 3-ring chemical sampling points of the main system.

[0062] A high-purity germanium multi-channel gamma spectrometer (model GEM30P4-76) and a 20ml mixed standard solution source from the China Institute of Metrology were used to measure the radioactive nuclides.

[0063] Step 5: Calculate the theoretical value of the nuclide in the main system

[0064] During the purification process of the main system, under the premise of ensuring that the purification bed efficiency remains unchanged, the radioactive nuclides of the main system are measured and the theoretical values ​​of the radioactive nuclides of the main system are calculated. The calculation formula is:

[0065]

[0066] in,

[0067] h: purification bed time (h);

[0068] L: Main system water volume (m 3 );

[0069] H: Purification flow rate (m 3 / h);

[0070] E: purification efficiency of purification bed (%);

[0071] C2: When purification starts, the main system actually detects the nuclide value (Bq / g);

[0072] C1: Theoretical target nuclide value (Bq / g) of the main system after purification for h hours.

[0073] Step 6: Calculate the net deposition rate or net shedding rate of activated corrosion products in the main system

[0074] Compare the actual value of the nuclide in the main system with the theoretical value deviation to determine whether the corrosion activation product in the main system is in a net deposition or net shedding state. Calculate the net deposition rate or net shedding rate of the corrosion activation product in the main system based on the actual value and theoretical value of the nuclide in the system.

[0075] After purification, if the actual detected nuclide value of the main system is greater than the theoretical target nuclide value of the main system, it indicates that the shedding rate at this stage is greater than the deposition rate, and the activated corrosion products in the main system are judged to be in a net shedding state. The net shedding rate of the corrosion activation products in the main system is calculated using the following formula:

[0076]

[0077] in,

[0078] A1: Net shedding rate of corrosion activation products (Bq / gh);

[0079] h: purification bed time (h);

[0080] C1: Theoretical target nuclide value of the main system after purification for h hours (Bq / g);

[0081] C3: Actual nuclide value (Bq / g) detected by the main system after purification for h hours.

[0082] After purification, if the theoretical target nuclide value of the main system is greater than the actual detected nuclide value of the main system, it indicates that the deposition rate at this stage is greater than the shedding rate, and it is determined that the activated corrosion products in the main system are in a net deposition state. The net deposition rate of the corrosion activation products in the main system is calculated using the following formula:

[0083]

[0084] in,

[0085] A2: Net deposition rate of corrosion activation products (Bq / gh);

[0086] h: purification bed time (h);

[0087] C1: Theoretical target nuclide of the main system after purification for h hours (Bq / g);

[0088] C3: Actual nuclides detected by the main system after purification for h hours (Bq / g).

[0089] Example 1

[0090] Calculation of the deposition and shedding of corrosion activation products in the primary circuit of the up-running ammonia deoxidation stage of the Fangjiashan Unit 1 of the Qinshan Nuclear Power Plant. The radionuclides that mainly affect the dose level of the overhaul personnel were used during the overhaul. 58 Co is calculated (the measurement period is 1 hour from 6:35 to 7:35 on September 28, 2023). The process is as follows Figure 1 As shown, including:

[0091] Step 1: Determine the purification status of the primary system during the measurement period

[0092] ① During the measurement period, the water volume of the primary system of the first circuit remains stable at 300L;

[0093] ②During the measurement period, the purification flow rate of the purification bed of the primary system of the first loop remained stable at 21.43t / h;

[0094] ③ During the measurement period, the purification efficiency of the primary system purification bed of the first loop remained stable at 99.85%.

[0095] Step 2: Measure the activity of radionuclides in the primary system of the primary circuit before and after purification

[0096] The sampling points for measuring the activity of radionuclides before and after purification are the chemical sampling points downstream of the RCV purification bed.

[0097] Step 3: Calculate the purification efficiency E of radionuclides

[0098] The calculation formula of the purification efficiency E of radionuclides is:

[0099] E = (activity before purification - activity after purification) / activity before purification

[0100] Step 4: Measure the actual value of the nuclide in the main system

[0101] The sampling points for measuring the actual nuclides of the main system are the 3-ring chemical sampling points of the main system.

[0102] The radioactive nuclides were measured using a high-purity germanium multi-channel gamma spectrometer (model GEM30P4-76) and a 20ml mixed standard solution source from the China Institute of Metrology. At the beginning of the purification, the actual nuclide value C2 of the main system was 464.98Bq / g; after one hour of purification, the actual nuclide value C3 of the main system was 1257Bq / g.

[0103] Step 5: Calculate the theoretical value of the nuclide in the main system

[0104] After 1 hour of purification, the theoretical target nuclide value C1 of the main system is calculated as:

[0105]

[0106] Step 6: Calculate the net deposition rate or net shedding rate of activated corrosion products in the main system

[0107] After 1 hour of purification, the theoretical target nuclide value C1 of the main system is 432.97Bq / g, and the actual detected nuclide value C3 of the main system is 1257Bq / g, then C3>C1, indicating that the shedding rate is greater than the deposition rate at this stage, and it is determined that the activated corrosion products in the main system are in a net shedding state. The net shedding rate A1 of the corrosion activation products in the main system is calculated as:

[0108]

[0109] Example 2

[0110] The unit status is the same as that selected in Implementation 1 (the measurement period is 1.15 hours from 7:35 to 8:44 on September 28, 2023), including:

[0111] Step 1: Determine the purification status of the primary system during the measurement period

[0112] ① During the measurement period, the water volume of the primary system of the first circuit remains stable at 300L;

[0113] ②During the measurement period, the purification flow rate of the purification bed of the primary system of the first loop remained stable at 19.91t / h;

[0114] ③ During the measurement period, the purification efficiency of the primary system purification bed of the first loop remained stable at 99.85%.

[0115] Step 2: Measure the activity of radionuclides in the primary system of the primary circuit before and after purification

[0116] Same as in Example 1

[0117] Step 3: Calculate the purification efficiency E of radionuclides

[0118] Same as in Example 1

[0119] Step 4: Measure the actual value of the nuclide in the main system

[0120] The sampling points and measurement methods of the actual nuclides in the main system are the same as those in Example 1.

[0121] At the beginning of purification, the actual detected nuclide value C2 of the main system was 1257Bq / g; after 1.15 hours of purification, the actual detected nuclide value C3 of the main system was 1175.3Bq / g.

[0122] Step 5: Calculate the theoretical value of the nuclide in the main system

[0123] After 1.15 hours of purification, the theoretical target nuclide value C1 of the main system is calculated as:

[0124]

[0125] Step 6: Calculate the net deposition rate or net shedding rate of activated corrosion products in the main system

[0126] After 1.15 hours of purification, the theoretical target nuclide value C1 of the main system is 1164.77Bq / g, and the actual detected nuclide value C3 of the main system is 1175.3Bq / g; then C3>C1, indicating that the shedding rate is greater than the deposition rate at this stage, and it is determined that the activated corrosion products in the main system are in a net shedding state. The net shedding rate A1 of the corrosion activation products in the main system is calculated as:

[0127]

[0128] Example 3

[0129] The unit status is the same as that selected in Implementation 1 (the measurement period is 1.35 hours from 8:44 to 10:05 on September 28, 2023), including:

[0130] Step 1: Determine the purification status of the primary system during the measurement period

[0131] ① During the measurement period, the water volume of the primary system of the first circuit remains stable at 300L;

[0132] ②During the measurement period, the purification flow rate of the purification bed of the primary system of the first loop remained stable at 18.81t / h;

[0133] ③ During the measurement period, the purification efficiency of the primary system purification bed of the first loop remained stable at 99.85%.

[0134] Step 2: Measure the activity of radionuclides in the primary system of the primary circuit before and after purification

[0135] Same as in Example 1

[0136] Step 3: Calculate the purification efficiency E of radionuclides

[0137] Same as in Example 1

[0138] Step 4: Measure the actual value of the nuclide in the main system

[0139] The sampling points and measurement methods of the actual nuclides in the main system are the same as those in Example 1.

[0140] At the beginning of purification, the actual detected nuclide value C2 of the main system was 1175.3Bq / g; after 1.35 hours of purification, the actual detected nuclide value C3 of the main system was 740.7Bq / g.

[0141] Step 5: Calculate the theoretical value of the nuclide in the main system

[0142] After 1.35 hours of purification, the theoretical target nuclide value C1 of the main system is calculated as:

[0143]

[0144] Step 6: Calculate the net deposition rate or net shedding rate of activated corrosion products in the main system

[0145] After 1.35 hours of purification, the theoretical target nuclide value C1 of the main system is 1080.05 Bq / g, and the actual detected nuclide value C3 of the main system is 740.7 Bq / g; then C3<C1, indicating that the deposition rate is greater than the shedding rate at this stage, and it is determined that the activated corrosion products in the main system are in a net deposition state. The net deposition rate A2 of the corrosion activation products in the main system is calculated as:

[0146]

[0147] Example 4

[0148] The unit status is the same as that selected in Implementation 1 (the measurement period is 0.5 hours from 10:05 to 10:35 on September 28, 2023), including:

[0149] Step 1: Determine the purification status of the primary system during the measurement period

[0150] ① During the measurement period, the water volume of the primary system of the first circuit remains stable at 300L;

[0151] ②During the measurement period, the purification flow rate of the purification bed of the primary system of the primary circuit remained stable at 20.26t / h;

[0152] ③ During the measurement period, the purification efficiency of the primary system purification bed in the first loop remained stable at 99.80%.

[0153] Step 2: Measure the activity of radionuclides in the primary system of the primary circuit before and after purification

[0154] Same as in Example 1

[0155] Step 3: Calculate the purification efficiency E of radionuclides

[0156] Same as in Example 1

[0157] Step 4: Measure the actual value of the nuclide in the main system

[0158] The sampling points and measurement methods of the actual nuclides in the main system are the same as those in Example 1.

[0159] At the beginning of purification, the actual detected nuclide value C2 of the main system was 740.7Bq / g; after 0.5 hours of purification, the actual detected nuclide value C3 of the main system was 680.89Bq / g.

[0160] Step 5: Calculate the theoretical value of the nuclide in the main system

[0161] After 0.5 hours of purification, the theoretical target nuclide value C1 of the main system is calculated as:

[0162]

[0163] Step 6: Calculate the net deposition rate or net shedding rate of activated corrosion products in the main system

[0164] After 0.5 hours of purification, the theoretical target nuclide value C1 of the main system is 716.15 Bq / g, and the actual detected nuclide value C3 of the main system is 680.89 Bq / g; then C3<C1, indicating that the deposition rate is greater than the shedding rate at this stage, and it is determined that the activated corrosion products in the main system are in a net deposition state. The net deposition rate A2 of the corrosion activation products in the main system is calculated as:

[0165]

[0166] Please see Table 1 for the data in Examples 1-4.

[0167] Table 1 Main system purification process data

[0168]

[0169]

[0170] The calculation of the deposition and shedding of corrosion activation products in a loop of the present invention can effectively reflect the state of deposition and shedding in the loop, and provide effective data support for taking corresponding chemical control.

[0171] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A method for calculating the deposition and shedding of corrosion activation products in a nuclear power plant primary circuit, characterized in that: The method comprises: Step 1, determine the purification status of the primary system of the primary circuit during the measurement period; Step 2, measuring the activity of radionuclides in the primary system of the primary loop before purification and after purification; Step 3, calculating the purification efficiency of radionuclides; Step 4, measuring the actual value of the nuclide in the main system; Step 5, calculate the theoretical value of nuclides in the main system; Step 6: Calculate the net deposition rate or net shedding rate of activated corrosion products in the main system.

2. The calculation method of the deposition and shedding of corrosion activation products in the primary circuit of a nuclear power plant according to claim 1 is characterized in that: The purification status of the primary-loop main system during the measurement in step 1 includes: the water volume of the primary-loop main system, the purification flow rate of the purification bed of the primary-loop main system, and the purification efficiency of the purification bed of the primary-loop main system.

3. The calculation method of the deposition and shedding of corrosion activation products in the primary circuit of a nuclear power plant according to claim 1 is characterized in that: The sampling points for measuring the activity of radionuclides before and after purification in step 2 are the chemical sampling points downstream of the RCV purification bed.

4. The calculation method of the deposition and shedding of corrosion activation products in the primary circuit of a nuclear power plant according to claim 3 is characterized in that: The calculation formula for the purification efficiency of radionuclides in step 3 is: E = (activity before purification - activity after purification) / activity before purification Where E is the purification efficiency of radionuclides.

5. The calculation method of the deposition and shedding of corrosion activation products in the primary circuit of a nuclear power plant according to claim 1 is characterized in that: The sampling point for measuring the actual value of the nuclide of the main system in step 4 is the main system 3-ring chemical sampling point.

6. The calculation method of the deposition and shedding of corrosion activation products in the primary circuit of a nuclear power plant according to claim 1 is characterized in that: The method for measuring the actual value of the nuclide of the main system in step 4 is to use a high-purity germanium multi-channel gamma spectrometer to measure the radioactive nuclide.

7. The calculation method of the deposition and shedding of corrosion activation products in the primary circuit of a nuclear power plant according to claim 1 is characterized in that: The theoretical value calculation formula of the nuclide of the main system in step 5 is: in, h: purification bed time; L: water volume of the main system; H: purification flow; E: purification efficiency of the purification bed; C2: When purification starts, the main system actually detects the nuclide value; C1: Theoretical target nuclide value of the main system after purification for h hours.

8. The method for calculating the deposition and shedding of corrosion activation products in the primary circuit of a nuclear power plant according to claim 1, characterized in that: The step 6 is specifically as follows: comparing the deviation between the actual value and theoretical value of the nuclides in the main system to determine whether the corrosion activation products in the main system are in a net deposition or net shedding state; and calculating the net deposition rate or net shedding rate of the corrosion activation products in the main system according to the actual value and theoretical value of the nuclides in the system.

9. A method for calculating the deposition and shedding of corrosion activation products in a primary circuit of a nuclear power plant according to claim 8, characterized in that: In step 6, after purification, if the actual detected nuclide value of the main system is greater than the theoretical target nuclide value of the main system, it indicates that the shedding rate at this stage is greater than the deposition rate, and it is determined that the activated corrosion products in the main system are in a net shedding state. The net shedding rate of the corrosion activation products in the main system is calculated, and the calculation formula is as follows: in, A1: Net shedding rate of corrosion activation products; h: purification bed time; C1: Theoretical target nuclide value of the main system after purification for h hours; C3: After purification for h hours, the main system actually detects the nuclide value.

10. The method for calculating the deposition and shedding of corrosion activation products in the primary circuit of a nuclear power plant according to claim 8, characterized in that: In step 6, after purification, if the theoretical target nuclide value of the main system is greater than the actual detected nuclide value of the main system, it indicates that the deposition rate at this stage is greater than the shedding rate, and it is determined that the activated corrosion products in the main system are in a net deposition state. The net deposition rate of the corrosion activation products in the main system is calculated, and the calculation formula is as follows: in, A2: Net deposition rate of corrosion activation products; h: purification bed time; C1: Theoretical target nuclide of the main system after purification for h hours; C3: After purification for h hours, the main system actually detects the nuclides.

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