A method for controlling turbidity in reactor pools before refueling during nuclear power plant overhauls
By controlling the water quality of the reactor pool at all stages, the problem of turbidity after the pool is filled has been solved, ensuring the smooth progress of loading and unloading operations and reducing the overhaul period and economic losses.
Patent Information
- Application Number
- CN202311054360.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-21
- Publication Date
- 2026-03-06
- Estimated Expiration
- 2043-08-21
AI Technical Summary
When the reactor pool of a nuclear power plant is filled with boron-containing water, the water becomes turbid, making it impossible for loading/unloading personnel to clearly see the components at the bottom of the reactor pool. This delays the critical path of the overhaul, affects the refueling and overhaul schedule, and causes economic losses.
From the preparation stage of the unit's refueling overhaul to the uphill stage, comprehensive front-end control is carried out on all aspects of the reactor pool water quality-related work, including purification of the refueling water tank, removal and purification of corrosion products, reactor pool inspection, water purification and preparation of purification units, to ensure that the water quality meets the loading/unloading conditions.
This effectively prevented water turbidity from affecting loading/unloading operations, ensuring the normal operation of loading/unloading and reducing delays in major overhauls and economic losses.
Smart Images
Figure CN119495458B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of reactor pool water quality turbidity control before refueling / unloading in nuclear power plants, and specifically relates to a method for controlling turbidity in reactor pools before refueling / unloading in nuclear power plants. Background Technology
[0002] Before refueling / unloading at a nuclear power plant, the reactor pool must be filled with boron-containing water to act as a bioshield for surrounding personnel. However, once the reactor pool is full, the turbidity of the water may prevent personnel from clearly seeing the internal components of the pressure vessel at the bottom of the pool, hindering the proper execution of refueling / unloading operations. In such cases, the water must be purified by the reactor pool purification unit before refueling / unloading can proceed, causing delays in the critical path of the overhaul, impacting the overall refueling / overhaul schedule, and resulting in significant economic losses.
[0003] This problem is common in many nuclear power plants in China. One nuclear power plant once delayed its critical overhaul path by about 16 hours because the reactor pool was filled with boron-containing water and the water quality became turbid. Summary of the Invention
[0004] The purpose of this invention is to provide a method for controlling turbidity in the reactor pool before refueling and unloading in a nuclear power plant. This method comprehensively controls all aspects of work related to reactor pool water quality during the nuclear power unit refueling and overhaul preparation stage, the downflow stage, the low-low water level stage, and the upflow stage, thereby achieving the goal of controlling the turbidity of the reactor pool water before refueling and unloading to prevent it from affecting the normal operation of the refueling and unloading work.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A method for controlling turbidity in reactor pools before refueling and unloading during nuclear power plant overhauls involves front-end control of water quality-related work in reactor pools during the preparation stage of unit refueling overhaul, the downflow stage, the low-low water level stage, and the upflow stage.
[0007] The preparation phase involves purifying the refueling water tank, the filling water source for the reactor pool, before the refueling overhaul of the unit. The goal is to purify the refueling water tank to a turbidity of <0.1 NTU, ensuring that the filling water source for the reactor pool is clear before refueling.
[0008] The downlink phase is from the purification of the primary circuit 80°C platform during the unit overhaul to the completion of unloading, including the concentrated peeling and purification of corrosion products on the primary circuit 80°C platform, the reactor pool inspection before filling the reactor pool with water, the water quality purification after the reactor pool is filled with water, and the judgment criteria for whether the turbidity of the reactor pool water meets the unloading conditions.
[0009] The low-low water level stage is from the completion of unloading the primary coolant to the refueling tank to the end of the low-low water level maintenance and before the primary system is filled with water, including the purification of the refueling tank and the inspection of the reactor pool before the primary circuit is filled with water.
[0010] The uplink phase is from primary circuit filling to fuel loading completion, including water purification after primary circuit filling, water purification before fuel loading in the reactor pool, and whether the turbidity of the reactor pool water meets the fuel loading conditions.
[0011] The centralized stripping and purification of corrosion products on the primary circuit platform at 80°C during the downlink phase involves adding excess hydrogen peroxide to the primary circuit coolant after it has cooled to 80°C, resulting in dissolved oxygen levels exceeding 1 mg / kg. This transforms the primary circuit coolant from a reducing environment to an oxidizing one, causing rapid oxidation, stripping, and dissolution of corrosion products on the reactor core and primary circuit system equipment surfaces. The stripped corrosion products are then centrally filtered and purified using the primary circuit system purification unit. The goal is to shut down the main pumps once the primary circuit coolant turbidity reaches <0.2 NTU, ensuring thorough purification of the corrosion products.
[0012] The pre-filling inspection of the reactor pool during the downflow phase involves checking the bottom of the reactor pool before unloading and filling it with water to ensure that there are no residual chemicals or greases from the maintenance work that could cause the water to become turbid after filling.
[0013] The water purification process after the reactor pool is filled with water during the downflow phase involves preparing the reactor pool purification unit online before the pool is filled with water. Once the reactor pool is filled, the purification unit can be put into operation in a timely manner to purify the water quality, so that the water quality in the reactor pool meets the unloading conditions as soon as possible.
[0014] The criterion for determining whether the turbidity of the reactor pool water during the downflow phase meets the unloading conditions is as follows: after the reactor pool is filled with water, the light gun is turned on to illuminate the upper tube seat of the fuel assembly inside the pressure vessel at the bottom of the pool. Whether the upper tube seat of the fuel assembly can be clearly seen is used as the criterion for determining whether the reactor pool water quality meets the unloading conditions.
[0015] The purification of the refueling water tank during the low-low water level stage involves purifying the water quality in the refueling water tank after the primary coolant is discharged into the refueling water tank for storage at the end of the unloading process. The aim is to purify the water in the refueling water tank to a turbidity of <0.1 NTU, ensuring that the reactor pool filling water source is clear before refueling.
[0016] The reactor pool inspection before primary circuit filling during the low-low water level stage involves inspecting the bottom of the reactor pool before fuel loading and before the primary circuit system is filled with water. This is to check for any residual chemicals or greases from the maintenance work that could cause the water to become turbid after filling.
[0017] The aforementioned primary loop filling water purification during the uplink phase involves purifying the primary loop system after low-level maintenance, which would otherwise cause turbidity in the primary loop system due to the accumulation of corrosion products or residual impurities from the maintenance process. To mitigate the risk of turbid water from the primary loop system being carried into the reactor pool during subsequent reactor pool filling, the primary loop purification unit is promptly activated after the primary loop system is filled to purify the primary loop water.
[0018] The reactor pool water purification process before the fuel loading in the up-flow stage involves preparing the reactor pool purification unit online before filling the reactor pool with water. Once the reactor pool is filled with water to a level exceeding the pump inlet of the reactor pool purification unit, the reactor pool purification unit is promptly put into operation to purify the water in the pool.
[0019] The criterion for determining whether the turbidity of the reactor pool water during the upflow phase meets the loading conditions is as follows: after the reactor pool is filled with water, the light gun is turned on to illuminate the lower grid plate pins inside the pressure vessel at the bottom of the pool. Whether the lower grid plate pins can be clearly seen is used as the criterion for determining whether the reactor pool water quality meets the loading conditions.
[0020] The beneficial effects achieved by this invention are as follows:
[0021] Develop corresponding control indicators for the chemical parameters of the relevant systems that affect the reactor pool water quality at each stage of the unit overhaul, so as to achieve front-end control.
[0022] Establish a clear and intuitive criterion for judging whether the turbidity of reactor pool water meets the loading / unloading conditions, so as to avoid loading / unloading personnel relying on their personal subjective visual judgment of whether the water quality affects the loading / unloading operation;
[0023] Adding a reactor pool inspection before loading / unloading and before filling the reactor pool with water can effectively avoid the impact of residual chemicals, grease and other impurities on water turbidity during maintenance work.
[0024] Prepare the purification unit before commissioning to ensure that it can be put into operation to purify water as soon as it meets the commissioning conditions, thereby maximizing the water purification time and improving water turbidity.
[0025] Based on the existing reactor pool filling scheme before fuel loading in the up-stage phase, an innovative approach is proposed: the reactor pool is filled to the water level required for the purification unit pump inlet to be put into operation, which greatly improves the purification effect of the reactor pool purification unit; and the water quality is purified simultaneously by making reasonable use of the filling time, thus adding extra purification time. Attached Figure Description
[0026] Figure 1 A schematic diagram of the turbidity control process in the reactor pool before refueling during a major overhaul of a nuclear power plant.
[0027] Figure 2 This is a schematic diagram of the primary loop system structure of a nuclear power plant.
[0028] In the diagram, 1 is the ion exchange resin bed; 2 is the pump; 3 is the filter; and 4 is the dosing tank. Detailed Implementation
[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0030] A method for controlling turbidity in reactor pools before refueling and unloading during nuclear power plant overhauls is proposed, which comprehensively controls all aspects of work related to reactor pool water quality from the preparation stage of unit refueling overhaul, the downflow stage, the low water level stage, and the upflow stage.
[0031] The preparation phase involves purifying the refueling water tank, the filling water source for the reactor pool, before the refueling overhaul. The goal is to purify the refueling water tank to a turbidity of <0.1 NTU, ensuring that the filling water source for the reactor pool is clear before refueling.
[0032] The downlink phase refers to the process from the purification of the primary circuit 80°C platform during the unit's overhaul to the completion of unloading. This mainly includes the concentrated stripping and purification of corrosion products from the primary circuit 80°C platform, reactor pool inspection before filling, water quality purification after the reactor pool is filled, and determining whether the turbidity of the reactor pool water meets the unloading conditions.
[0033] The low-low water level stage refers to the period from the completion of refueling of the primary coolant (i.e., boron-containing water) to the refueling tank, until the end of the low-low water level maintenance and before the primary system is filled with water. This mainly includes purification of the refueling tank and inspection of the reactor pool before primary system filling.
[0034] The uplink phase refers to the process from primary circuit filling to fuel loading completion. It mainly includes water purification after primary circuit filling, water purification before fuel loading in the reactor pool, and determining whether the turbidity of the reactor pool water meets the fuel loading criteria.
[0035] Furthermore, the centralized stripping and purification of corrosion products on the 80°C platform of the primary circuit during the downlink phase involves adding excess hydrogen peroxide to the primary circuit coolant after it has been cooled to 80°C, resulting in dissolved oxygen levels >1 mg / kg. This transforms the primary circuit coolant from a reducing environment to an oxidizing environment, causing corrosion products on the reactor core and primary circuit system equipment surfaces to oxidize, detach, and dissolve rapidly. The detached corrosion products are then centrally filtered and purified using the primary circuit purification unit. To prevent corrosion products from accumulating in the primary circuit piping and causing turbidity after the primary circuit is filled during the uplink phase if the main pump is shut down before the primary circuit is thoroughly purified after the concentrated stripping of corrosion products on the 80°C platform, it is desirable to shut down the main pump after the primary circuit coolant is purified to a turbidity level <0.2 NTU, thus ensuring thorough purification of the corrosion products.
[0036] Furthermore, the pre-filling inspection of the reactor pool during the downlink phase involves inspecting the bottom of the reactor pool before unloading and before it is filled with water to check for any residual chemicals, grease, or other impurities that may cause turbidity in the water after filling, which may have been present during maintenance work.
[0037] Furthermore, the water purification after the reactor pool is filled with water during the downflow phase involves preparing the reactor pool purification unit online before the reactor pool is filled with water. Once the reactor pool is filled with water, the reactor pool purification unit can be put into operation in a timely manner to purify the water quality, so that the reactor pool water quality meets the unloading conditions as soon as possible.
[0038] Furthermore, the criterion for determining whether the turbidity of the reactor pool water during the downflow phase meets the unloading conditions is to open the pool light gun after the reactor pool is filled with water and illuminate the upper tube seat of the fuel assembly inside the pressure vessel at the bottom of the pool. Whether the upper tube seat of the fuel assembly can be clearly seen is used as the criterion for determining whether the reactor pool water quality meets the unloading conditions.
[0039] Furthermore, the purification of the refueling water tank during the low-low water level stage involves purifying the water quality in the refueling water tank after the primary coolant is discharged into the refueling water tank for storage at the end of the unloading process. The aim is to purify the water in the refueling water tank to a turbidity of <0.1 NTU, ensuring that the reactor pool filling water source is clear before refueling.
[0040] Furthermore, the reactor pool inspection before primary circuit filling during the low-low water level stage involves inspecting the bottom of the reactor pool before the primary circuit system is filled with water, to check whether there are any chemicals, greases, or other impurities that may cause the reactor pool to become turbid after filling, which may have been left over from the maintenance work.
[0041] Furthermore, the primary loop water purification during the uplink phase occurs after the primary loop system is filled with water following the completion of low-level maintenance. This process stirs up corrosion products deposited in the primary loop system pipes or impurities remaining during maintenance, resulting in turbid water after filling the primary loop system. To mitigate the turbidity of the reactor pool water caused by the turbid water from the primary loop system being carried into the reactor pool during subsequent filling, the primary loop purification unit needs to be put into operation promptly after the primary loop system is filled to purify the primary loop water.
[0042] Furthermore, the reactor pool water purification process before the upstream fuel loading phase involves ensuring the reactor pool purification unit is operational online before the reactor pool is filled with water. Once the water level in the reactor pool exceeds the pump inlet of the purification unit, the purification unit is promptly activated to purify the water. Activating the purification unit as early as possible, while keeping the reactor pool water level as low as possible, maximizes its purification effect. Secondly, by activating the purification unit in advance, purification can be carried out simultaneously during the subsequent reactor pool filling process, making efficient use of the filling time to achieve water purification concurrently, ensuring the reactor pool water quality meets the fuel loading requirements as soon as possible.
[0043] Furthermore, the criterion for determining whether the turbidity of the reactor pool water in the upflow phase meets the loading conditions is to illuminate the lower grid plate pins inside the pressure vessel at the bottom of the pool with a light gun after the reactor pool is filled with water, and use the visibility of the lower grid plate pins as the criterion for determining whether the reactor pool water quality meets the loading conditions.
[0044] This application discloses a method for controlling turbidity in reactor pools before refueling during nuclear power plant overhauls. This method comprehensively controls all aspects of work related to reactor pool water quality, thereby achieving the goal of controlling the impact of turbidity in the reactor pool water on the normal operation of refueling / unloading.
[0045] The key points and areas to be protected in this invention are:
[0046] A method for controlling turbidity in reactor pools before refueling and unloading during nuclear power plant overhauls provides comprehensive front-end control of reactor pool water quality across the entire process, including the preparation phase, downflow phase, low-low water level phase, and upflow phase. The main components include:
[0047] Develop corresponding control indicators for the chemical parameters of the relevant systems that affect the reactor pool water quality at each stage of the unit overhaul, so as to achieve front-end control.
[0048] Establish a clear and intuitive criterion for judging whether the turbidity of reactor pool water meets the loading / unloading conditions, so as to avoid loading / unloading personnel relying on their personal subjective visual judgment of whether the water quality affects the loading / unloading operation;
[0049] Adding a reactor pool inspection before loading / unloading and before filling the reactor pool with water can effectively avoid the impact of residual chemicals, grease and other impurities on water turbidity during maintenance work.
[0050] Prepare the purification unit before commissioning to ensure that it can be put into operation to purify water as soon as it meets the commissioning conditions, thereby maximizing the water purification time and improving water turbidity.
[0051] Based on the existing reactor pool filling scheme before fuel loading in the up-stage phase, an innovative approach is proposed: the reactor pool is filled to the water level required for the purification unit pump inlet to be put into operation, which greatly improves the purification effect of the reactor pool purification unit; and the water quality is purified simultaneously by making reasonable use of the filling time, thus adding extra purification time.
[0052] 1. Before the unit's refueling overhaul, the refueling water tank should be purified until the turbidity of the refueling water tank is <
[0053] 0.1 NTU, ensuring the reactor pool filling water source is clear before unloading.
[0054] 2. After the primary coolant in the unit is cooled to 80°C during the overhaul, the primary coolant purification unit is shut down. Then, 15L of 35% hydrogen peroxide is added to the primary coolant. The dissolved oxygen in the primary coolant is tested. Once it is confirmed that the dissolved oxygen is >1mg / kg, the primary coolant purification unit is restarted to centrally filter and purify the corrosion products that have oxidized and detached, thereby reducing the turbidity of the primary coolant.
[0055] 3. Check whether the purification efficiency of the primary coolant purification unit meets the requirements. If the pressure difference of the filter in the purification unit exceeds 0.25MPa, the filter is faulty and needs to be replaced; if the Co-58 at the outlet of the ion exchange resin bed in the purification unit is greater than 1000MBq / t and the Co-58 purification efficiency is less than 90% or the pressure difference is high and affects operation, then use the spare ion exchange resin bed for purification.
[0056] 4. To avoid the accumulation of corrosion products in the primary loop system pipelines due to incomplete purification after the corrosion products have been concentrated and peeled off from the 80℃ platform, resulting in turbid water quality after the primary loop is filled during the upward phase, it is expected that the main pump will be shut down after the primary loop coolant is purified to a turbidity of <0.2 NTU.
[0057] 5. Before unloading and filling the reactor pool with water, inspect the bottom of the reactor pool to check for any chemicals, grease, or other residues left during the maintenance work. If any are found, contact cleaning personnel to clean them thoroughly to prevent residual chemicals, grease, or other impurities from causing turbidity in the reactor pool after filling.
[0058] 6. Before the reactor pool is filled with water, the reactor pool purification unit should be put into operation online in advance. After the reactor pool is filled with water, the reactor pool purification unit should be put into operation as soon as possible to purify the water quality.
[0059] 7. After the reactor pool is filled with water, turn on the reactor pool light gun to illuminate the fuel assembly upper tube sockets inside the pressure vessel at the bottom of the pool. If the fuel assembly upper tube sockets are clearly visible, the reactor pool water quality meets the unloading conditions and the unloading operation can be carried out. If the fuel assembly upper tube sockets are not clearly visible, continue to purify the reactor pool water until the fuel assembly upper tube sockets are clearly visible.
[0060] 8. After the primary coolant is discharged into the refueling water tank for storage after unloading, the water in the refueling water tank is purified. It is expected that the turbidity of the water in the refueling water tank will be <0.1 NTU to ensure that the filling water source of the reactor pool is clear before loading.
[0061] 9. Before the primary loop system is filled with water, check the bottom of the reactor pool to see if there are any chemicals, greases, or other residues left during the maintenance work. If so, contact the cleaning personnel to clean them up to avoid the residual chemicals, greases, or other impurities causing the water in the reactor pool to become turbid after filling.
[0062] 10. After the primary loop system is filled with water, the primary loop coolant purification unit shall be put into operation in a timely manner to purify the primary loop coolant.
[0063] 11. Before the reactor pool is filled with water before loading fuel, the reactor pool purification unit should be put into online operation in advance. After the reactor pool is filled with water to the level above the pump inlet of the reactor pool purification unit, the reactor pool purification unit should be put into operation as soon as possible to purify the water quality in the pool. This will maximize the purification effect of the reactor pool purification unit and make reasonable use of the filling time to achieve water purification simultaneously, thus adding extra purification time.
[0064] 12. After the reactor pool is filled with water, turn on the reactor pool light gun to illuminate the lower grid plate pins inside the pressure vessel at the bottom of the pool. If the lower grid plate pins are clearly visible, the reactor pool water quality meets the loading conditions and the loading operation can be carried out. If the lower grid plate pins are not clearly visible, continue to purify the reactor pool water until the lower grid plate pins are clearly visible.
Claims
1. A method for controlling the turbidity of a reactor pool prior to the unloading of a nuclear power plant during an outage, characterized in that: The reactor pool water quality related work is controlled in the preparation stage, the descending stage, the low-low water level stage and the ascending stage of the refueling overhaul of the nuclear power unit. The preparation stage is to purify the refueling water tank before the reactor pool is filled with water before the refueling overhaul of the nuclear power unit, and the turbidity of the refueling water tank is expected to be less than 0.1 NTU, so as to ensure that the water source of the reactor pool is clear before the refueling. The descending stage is to purify the 80℃ platform corrosion products of the primary loop to the completion of the unloading, including the 80℃ platform corrosion product stripping purification, the reactor pool inspection before the reactor pool is filled with water, the water quality purification after the reactor pool is filled with water, and the judgment criterion of whether the turbidity of the reactor pool water quality meets the unloading condition. The low-low water level stage is from the completion of the unloading to the completion of the primary loop system filling before the filling of the reactor pool, including the refueling water tank purification and the reactor pool inspection before the primary loop is filled with water. The ascending stage is from the primary loop filling to the completion of the loading, including the water quality purification after the primary loop is filled with water, the reactor pool water quality purification before the loading, and the judgment criterion of whether the turbidity of the reactor pool water quality meets the loading condition.
2. The nuclear power plant refueling outage reactor basin clouding control method of claim 1, wherein: The 80℃ platform corrosion product stripping purification of the descending stage is to add excess hydrogen peroxide to the primary loop coolant after the primary loop coolant is cooled to 80℃, so that the dissolved oxygen in the primary loop coolant is greater than 1 mg / kg, the primary loop coolant is changed from a reducing environment to an oxidizing environment, the corrosion products on the surface of the reactor core and the primary loop system equipment are rapidly oxidized, stripped and dissolved, and the stripped corrosion products are concentrated, filtered and purified by the primary loop system purification unit; the primary pump is stopped after the primary loop coolant is purified to a turbidity of less than 0.2 NTU, and the corrosion product purification is completed.
3. The nuclear power plant refueling outage reactor basin clouding control method of claim 1, wherein: The reactor pool inspection before the reactor pool is filled with water in the descending stage is to inspect the bottom of the reactor pool before the reactor pool is filled with water to determine whether there are any impurities such as chemicals and grease remaining in the reactor pool during the maintenance work, which may cause turbidity of the water in the reactor pool after the reactor pool is filled with water.
4. The nuclear power plant refueling outage reactor basin clouding control method of claim 1, wherein: The water quality purification after the reactor pool is filled with water in the descending stage is to ensure that the reactor pool purification unit is online before the reactor pool is filled with water, so that the reactor pool purification unit can be put into operation in time after the reactor pool is filled with water to purify the water quality of the reactor pool, so that the water quality of the reactor pool meets the unloading condition as soon as possible.
5. The nuclear power plant refueling outage reactor basin turbidity control method of claim 1, wherein: The judgment criterion of whether the turbidity of the reactor pool water quality meets the unloading condition in the descending stage is to open the light gun to irradiate the upper nozzle of the fuel assembly in the pressure vessel at the bottom of the reactor pool, and to determine whether the upper nozzle of the fuel assembly can be clearly seen by visual observation as the judgment criterion of whether the water quality of the reactor pool meets the unloading condition.
6. The nuclear power plant refueling outage reactor basin clouding control method of claim 1, wherein: The refueling water tank purification in the low-low water level stage is to purify the water quality of the refueling water tank after the primary loop coolant is discharged to the refueling water tank, and the turbidity of the water quality of the refueling water tank is expected to be less than 0.1 NTU, so as to ensure that the water source of the reactor pool is clear before the loading.
7. The nuclear power plant refueling outage reactor sump clouding control method of claim 1, wherein: The low-low water level stage one loop filling water pool inspection is to inspect the bottom of the reactor pool before the one loop system is filled with water before loading, whether there are chemicals, grease left over during the maintenance work causing the water quality to be turbid after the reactor pool is filled with water.
8. The nuclear power plant refueling outage reactor sump clouding control method of claim 1, wherein: The uplink stage one loop filling water quality purification is to stir up the corrosion products deposited in the one loop system pipeline or the impurities left over during the maintenance after the one loop system is filled with water after the low-low water level maintenance, so that the water quality is turbid after the one loop system is filled with water; in order to alleviate the turbid water in the one loop system being brought into the reactor pool to cause the water quality of the reactor pool to be turbid when the reactor pool is filled with water, the one loop purification unit is promptly put into operation to purify the water quality of the one loop after the one loop system is filled with water.
9. The nuclear power plant refueling outage reactor sump clouding control method of claim 1, wherein: The uplink stage reactor pool filling water quality purification before loading is to make the reactor pool purification unit ready for online work in advance before the reactor pool is filled with water, and the reactor pool purification unit is promptly put into operation to purify the water quality of the pool after the reactor pool is filled with water to a water level exceeding the suction inlet of the reactor pool purification unit.
10. The nuclear power plant refueling outage reactor sump clouding control method of claim 1, wherein: The uplink stage reactor pool water quality turbidity whether to meet the loading condition judgment criterion is to open the pool light gun to irradiate the lower grid plate pin in the lower part of the pressure vessel at the bottom of the pool after the reactor pool is filled with water, whether the lower grid plate pin can be visually seen as the judgment criterion whether the water quality of the reactor pool meets the loading condition.