Tracking and monitoring method for integrity of domestic nuclear fuel assembly
阅读说明：本技术 一种国产核燃料组件完整性跟踪监督方法 (Tracking and monitoring method for integrity of domestic nuclear fuel assembly ) 是由 林锘涵 邹森 廖泽军 邓志新 王玲彬 石中华 钟波 尤益辉 胡胜 许进 周忠政 于 2019-10-28 设计创作，主要内容包括：本发明属于核燃料技术应用领域,具体涉及一种国产核燃料组件完整性跟踪监督方法。本发明包括以下步骤：步骤一：改进反应堆一回路系统水质控制方法；步骤二：改进主系统放射性核素分析方法；步骤三：专门制定辐照考验临时运行指令；步骤四：辐照考验燃料组件辐照后池边检查。本发明在不改变原运行条件的情况下,实现国产燃料组件入堆辐照考验期间完整性监督,中核运行通过改进反应堆一回路系统水质控制、改进主系统放射性核素分析方法,制定CF2辐照考验临时运行指令等创新方法,从而保证新型国产燃料组件入商用堆辐照考验过程中,燃料完整性和反应堆安全性得到保障。(The invention belongs to the technical application field of nuclear fuel, and particularly relates to a tracking and monitoring method for integrity of a domestic nuclear fuel assembly. The invention comprises the following steps: the method comprises the following steps: improving a water quality control method of a reactor primary loop system; step two: improving the primary system radionuclide analysis method; step three: specially making an irradiation examination temporary operation instruction; step four: and (4) performing cell edge inspection after irradiation of the irradiation test fuel assembly. The invention realizes the integrity supervision of the domestic fuel assembly during the irradiation examination period when the domestic fuel assembly enters the reactor without changing the original operation condition, and the mesonuclear operation establishes CF2 irradiation examination temporary operation instructions and other innovative methods by improving the water quality control of a loop system of the reactor and improving a main system radionuclide analysis method, thereby ensuring the fuel integrity and the reactor safety in the irradiation examination process when the novel domestic fuel assembly enters the commercial reactor.)
1. A method for tracking and supervising integrity of a domestic nuclear fuel assembly comprises the following steps: the method comprises the following steps: improving a water quality control method of a reactor primary loop system; step two: improving the primary system radionuclide analysis method; step three: specially making an irradiation examination temporary operation instruction; step four: and (4) performing cell edge inspection after irradiation of the irradiation test fuel assembly.
2. The method for tracking and supervising the integrity of the domestic nuclear fuel assembly as claimed in claim 1, wherein: the first step is as follows: the method for improving the water quality control of the primary loop system of the reactor specifically comprises the following steps: the system hydrogen concentration control is optimized, the control limit value of the dissolved hydrogen content of the main system is optimized, and the control is adjusted from 25cc/kg to 20 cc/kg.
3. The method for tracking and supervising the integrity of the domestic nuclear fuel assembly as claimed in claim 1, wherein: the second step is that: the method for improving the analysis of the radionuclide of the primary system comprises the following steps: iodine separation operation:
(1) adding 50ml of main coolant into a 200ml separating funnel, adding 2ml of iodine carrier, shaking for 1 minute, adding 5ml of 5% sodium hypochlorite solution, shaking for 1 minute, discharging air, standing for a moment, adding 6ml of 1mol/L hydroxylamine hydrochloride solution, and shaking for 1 minute;
(2) add 15ml carbon tetrachloride to the separatory funnel, add 1: 1, concentrating nitric acid until the color of the solution turns yellow, shaking for 1 minute, simultaneously discharging gas in a fume hood, placing for layering, placing carbon tetrachloride into another separating funnel, adding 10ml of carbon tetrachloride and 1ml of 5mol/L sodium nitrite solution into the first separating funnel, shaking for 1 minute, extracting once again, if iodine is extracted for the second time, the color of an organic phase is still darker, which indicates that iodine is not extracted completely, adding 10ml of carbon tetrachloride and 1ml of 5mol/L sodium nitrite for re-extraction, until the color of the organic phase is light, discarding a water phase, and leaving an organic phase;
(3) washing the organic phase twice with equal volume of desalted water, layering the two phases, and removing the water phase;
(4) adding 20ml of desalted water into the organic phase, dropwise adding 2ml of 1mol/L sodium hydroxide, adding 2ml of 30% hydrogen peroxide, shaking uniformly for two minutes, back-extracting iodine, standing for layering, removing a carbon tetrachloride layer, transferring the extracted water phase into a 250ml polyethylene bottle, diluting the water phase to 250ml of scale line with the desalted water, and sealing to be tested.
4. A domestic nuclear fuel assembly integrity tracking supervision method as claimed in claim 3, wherein: the second step is that: the method for improving the analysis of the radionuclide of the primary system further comprises the following steps: determination of iodine recovery:
(1) replacing the main coolant with desalted water, repeating the above steps to obtain a back extraction, and transferring the water phase into a main beaker;
(2) the beaker is placed on an electric furnace to be heated slowly, after residual carbon tetrachloride and hydrogen peroxide are burnt out, 2mL of nitric acid solution of 6mol/L is added, 3mL of 1% silver nitrate is immediately dripped to precipitate silver iodide, the silver iodide is heated and boiled for ten minutes and is stirred when not needed, after the precipitate is coagulated, the precipitate is filtered while hot on weighed filter paper in a detachable funnel, then the precipitate is washed three times by hot nitric acid solution of 0.1mol/L, then the precipitate is washed twice by 95% ethanol and ether in sequence, finally the sample is placed in an oven of 100 ℃ to be dried for 20 minutes, the sample is weighed after being cooled, and the chemical recovery rate of the iodine is calculated.
5. A domestic nuclear fuel assembly integrity tracking supervision method as claimed in claim 3, wherein: the third step is that: specially making an irradiation test temporary operation instruction, and loading 2 groups of N36 characteristic fuel assemblies into a reactor core, wherein the 2 groups of fuel assemblies are irradiated in the reactor under the reactor operation condition to test 4 fuel cycles; then 4 groups of CF2 of autonomous brand are loaded in the reactor core to test fuel assemblies, and the transient times of the unit are reduced in the period, so that the safe and stable operation of the reactor is maintained.
6. The method for tracking and supervising the integrity of the domestic nuclear fuel assembly as claimed in claim 1, wherein: the fourth step is that: the method specifically comprises the following steps of: during the three fuel circulation tests, after each fuel circulation is finished, the irradiation test fuel assembly is subjected to pool-side inspection in a spent fuel pool of the irradiation test nuclear power unit, and whether various irradiation performances after the irradiation test of the CF2 fuel assembly meet the requirements of design indexes is verified.
7. A domestic nuclear fuel assembly integrity tracking supervision method as claimed in claim 7, wherein: the pool edge inspection item comprises:
the CF2 fuel assembly all-out-of-stack inspection items comprise:
checking the appearance of the N36 zirconium alloy fuel rod;
n36 zirconium alloy fuel rod length;
n36 zirconium alloy fuel rod diameter;
the thickness of the oxide film on the surface of the N36 zirconium alloy fuel rod;
the spacing between the N36 zirconium alloy fuel rods and the upper and lower pipe seats is equal;
CF2 fuel assembly visual inspection;
CF2 fuel assembly physical dimension inspection;
and (3) checking the surface oxidation film of the fuel rod of the CF2 fuel assembly.
8. The domestic nuclear fuel assembly integrity tracking and supervision method according to claim 6, wherein: the third step is that: specially formulating an irradiation examination temporary operation instruction, and executing according to the following temporary operation instruction when the specific activity of the reactor coolant changes:
(1) average activity is expressed as I-131 equivalent: 0.22E10Bq/t < A < 0.3E10Bq/t (0.06Ci/t < A < 0.08Ci/t), and when the average specific activity reaches 0.22E10Bq/t (0.06Ci/t), the pile is stopped within 2 months;
(2) average activity is expressed as I-131 equivalent: a is more than 0.3E10Bq/t (0.08Ci/t), and when A reaches 0.3E10Bq/t (0.08Ci/t), the pile is stopped within 15 days;
(3) transient activity is expressed as I-131 equivalent
0.44E10Bq/t＜A＜1.85E10Bq/t(0.12Ci/t)＜A＜(0.5Ci/t)
Total transient activity of inert gas
37E10Bq/t＜A＜148E10Bq/t
(10Ci/t < A < 40Ci/t), no special requirements are required, but the supervision is required to be strengthened;
(4) i-131 equivalent represents transient value
1.85E10Bq/t＜A＜3.7E10Bq/t
(0.5Ci/t < A < 1Ci/t) or
Total transient activity of inert gas
148E10Bq/t＜A＜296E10Bq/t
(40Ci/t < A < 80Ci/t), and stopping the pile within 48 hours
Reactor coolant discharge into boron recovery system
Purging gaseous substances in the containment tank into the exhaust gas treatment system
All RCV purification desalinization devices are put into operation under the condition of rated let-down flow;
(5) i-131 equivalent represents transient value
A > 3.7E10Bq/t (1Ci/t) or total transient activity of inert gas
A is more than 296E10Bq/t (80Ci/t), and the reactor is stopped in 6 hours;
(6) transient value represented by I-134
A > 0.55E10Bq/t (0.15Ci/t), no special instruction, but attention is paid to strengthen monitoring;
(7) transient specific activity expressed as Xe-133
A > 9.25E10Bq/t (2.5Ci/t) or transient specific activity rateAnd Xe-133 > 3.7E10Bq/t (1Ci/t) (3), it must be brought down from maximum operating power to a hot shutdown at a rate of 30MW/min if at least 1 steam generator fails at 5% of the heat transfer tubes.
Technical Field
The invention belongs to the technical application field of nuclear fuel, and particularly relates to a tracking and monitoring method for integrity of a domestic nuclear fuel assembly.
Background
In consideration of environmental protection, ecology, energy supply and the like, nuclear power is accepted and adopted by more and more countries as a safe, clean, low-carbon and reliable energy source. Fuel assemblies and related assemblies are core components of nuclear reactors. The fuel assembly is precisely processed from nuclear fuel, and is subjected to nuclear fission in a reactor to release energy and convert the energy to generate power, and related assemblies can ensure the safe, controllable and stable operation of the reactor.
At present, the nuclear power generating unit type in the world is mainly a pressurized water reactor, so that the technology of a pressurized water reactor fuel assembly and related assemblies is rapidly developed. Typically, West House, USA, developed, designed and manufactured a high PERFORMANCE fuel assembly designated PERFOMANCE + (P +) with an average discharge fuel consumption of 55 GW.d/t. On the basis of the successful operation of the P + fuel assembly, the west house company has developed a ROBUST fuel assembly. After the ROBUST fuel assembly, based on years of fuel assembly design, production and use experience, westinghouse corporation has proposed a new pressurized water reactor fuel assembly known as ngf (next Generation fuel). In addition, West House corporation has also developed AP-1000 fuel assemblies based on P + and ROBUST fuel assemblies for its own AP-1000 three generations of pressurized water reactor nuclear power plants.
So far, the design and manufacture of nuclear fuel assemblies for the reactor of a pressurized water reactor nuclear power station in China still do not obtain independent intellectual property rights, and main raw material parts still depend on import from abroad, namely the supply safety of the fuel assemblies for the nuclear power station in China is influenced and the nuclear power strategic export in China is also influenced. In order to realize design autonomy and manufacturing localization of fuel assemblies, ensure safe and reliable supply of the fuel assemblies for the domestic nuclear power generating units and meet strategic requirements of nuclear power sustainable development and nuclear power generating unit export in China, a pressurized water reactor fuel element design and manufacturing technology is listed as a key scientific and technological special item of a mesonuclear group by the mesonuclear group, and the domestic fuel assemblies with independent intellectual property rights are researched and developed by depending on a domestic fuel element research and development system.
The design, research and development and manufacture of the novel domestic fuel assembly are carried out before formal commercial promotion in a laboratory mode, the performance of the novel fuel assembly is verified, irradiation practice is not carried out in a large-scale commercial reactor, and therefore critical practical experience is lacked in research, development and promotion of the whole novel domestic fuel assembly.
In 2013, the mesonuclear group reaches the task of CF2 pilot fuel assembly stacking irradiation examination under the Qinshan nuclear power according to the requirements of a special implementation scheme, stacking irradiation examination is started in a refueling core of a No. 2 unit of a second nuclear power plant in Qinshan in the same year at 6 months in a No. 10 fuel cycle (U2C10), and in order to ensure the operation safety and integrity supervision of a novel fuel assembly during the in-pile irradiation examination, a method for integrity tracking supervision aiming at the novel domestic fuel assembly irradiation examination needs to be established.
Disclosure of Invention
The invention aims to establish a method for irradiation examination of novel domestic fuel assemblies in reactor, a large commercial nuclear power station strictly complies with requirements of national relevant departments and technical specifications (FASR) and relevant criteria, integrity supervision during irradiation examination of domestic fuel assemblies in reactor is realized under the condition of not changing original operation conditions, and innovative methods such as CF2 irradiation examination temporary operation instructions are formulated by improving water quality control of a reactor loop system and improving a main system radionuclide analysis method in the process of medium nuclear operation, so that the fuel integrity and the reactor safety are guaranteed in the irradiation examination process of novel domestic fuel assemblies in reactor.
The invention is realized by the following steps:
a method for tracking and supervising integrity of a domestic nuclear fuel assembly comprises the following steps: the method comprises the following steps: improving a water quality control method of a reactor primary loop system; step two: improving the primary system radionuclide analysis method; step three: specially making an irradiation examination temporary operation instruction; step four: and (4) performing cell edge inspection after irradiation of the irradiation test fuel assembly.
The method comprises the following steps: the method for improving the water quality control of the primary loop system of the reactor specifically comprises the following steps: the system hydrogen concentration control is optimized, the control limit value of the dissolved hydrogen content of the main system is optimized, and the control is adjusted from 25cc/kg to 20 cc/kg.
Step two: the method for improving the analysis of the radionuclide of the primary system comprises the following steps:
iodine separation operation:
(1) adding 50ml of main coolant into a 200ml separating funnel, adding 2ml of iodine carrier, shaking for 1 minute, adding 5ml of 5% sodium hypochlorite solution, shaking for 1 minute, discharging air, standing for a moment, adding 6ml of 1mol/L hydroxylamine hydrochloride solution, and shaking for 1 minute;
(2) add 15ml carbon tetrachloride to the separatory funnel, add 1: 1, concentrating nitric acid until the color of the solution turns yellow, shaking for 1 minute, simultaneously discharging gas in a fume hood, placing for layering, placing carbon tetrachloride into another separating funnel, adding 10ml of carbon tetrachloride and 1ml of 5mol/L sodium nitrite solution into the first separating funnel, shaking for 1 minute, extracting once again, if iodine is extracted for the second time, the color of an organic phase is still darker, which indicates that iodine is not extracted completely, adding 10ml of carbon tetrachloride and 1ml of 5mol/L sodium nitrite for re-extraction, until the color of the organic phase is light, discarding a water phase, and leaving an organic phase;
(3) washing the organic phase twice with equal volume of desalted water, layering the two phases, and removing the water phase;
(4) adding 20ml of desalted water into the organic phase, dropwise adding 2ml of 1mol/L sodium hydroxide, adding 2ml of 30% hydrogen peroxide, shaking uniformly for two minutes, back-extracting iodine, standing for layering, removing a carbon tetrachloride layer, transferring the extracted water phase into a 250ml polyethylene bottle, diluting the water phase to 250ml of scale line with the desalted water, and sealing to be tested.
Determination of iodine recovery:
(1) replacing the main coolant with desalted water, repeating the above steps to obtain a back extraction, and transferring the water phase into a main beaker;
(2) the beaker is placed on an electric furnace to be heated slowly, after residual carbon tetrachloride and hydrogen peroxide are burnt out, 2mL of nitric acid solution of 6mol/L is added, 3mL of 1% silver nitrate is immediately dripped to precipitate silver iodide, the silver iodide is heated and boiled for ten minutes and is stirred when not needed, after the precipitate is coagulated, the precipitate is filtered on weighed filter paper in a detachable funnel while the precipitate is hot, then the precipitate is washed three times by hot nitric acid solution of 0.1mol/L, then the precipitate is washed twice by 95% ethanol and ether in sequence, finally the sample is placed in an oven of 100 ℃ to be dried for 20 minutes, the sample is weighed after being cooled, and the chemical recovery rate of the iodine is calculated.
Step three: specially making an irradiation test temporary operation instruction, and loading 2 groups of N36 characteristic fuel assemblies into a reactor core, wherein the 2 groups of fuel assemblies are irradiated in the reactor under the reactor operation condition to test 4 fuel cycles; then 4 groups of CF2 of autonomous brand are loaded in the reactor core to test fuel assemblies, and the transient times of the unit are reduced in the period, so that the safe and stable operation of the reactor is maintained.
Specially formulating an irradiation examination temporary operation instruction, and executing according to the following temporary operation instruction when the specific activity of the reactor coolant changes:
(1) average activity is expressed as I-131 equivalent: 0.22E10Bq/t < A < 0.3E10Bq/t (0.06Ci/t < A < 0.08Ci/t), and when the average specific activity reaches 0.22E10Bq/t (0.06Ci/t), the pile is stopped within 2 months;
(2) average activity is expressed as I-131 equivalent: a is more than 0.3E10Bq/t (0.08Ci/t), and when A reaches 0.3E10Bq/t (0.08Ci/t), the pile is stopped within 15 days;
(3) transient activity is expressed as I-131 equivalent
0.44E10Bq/t＜A＜1.85E10Bq/t(0.12Ci/t)＜A＜(0.5Ci/t)
Total transient activity of inert gas
37E10Bq/t＜A＜148E10Bq/t
(10Ci/t < A < 40Ci/t), no special requirements are required, but the supervision is required to be strengthened;
(4) i-131 equivalent represents transient value
1.85E10Bq/t＜A＜3.7E10Bq/t
(0.5Ci/t < A < 1Ci/t) or
Total transient activity of inert gas
148E10Bq/t＜A＜296E10Bq/t
(40Ci/t < A < 80Ci/t), and stopping the pile within 48 hours
Reactor coolant discharge into boron recovery system
Purging gaseous substances in the containment tank into the exhaust gas treatment system
All RCV purification desalinization devices are put into operation under the condition of rated let-down flow;
(5) i-131 equivalent represents transient value
A > 3.7E10Bq/t (1Ci/t) or total transient activity of inert gas
A is more than 296E10Bq/t (80Ci/t), and the reactor is stopped in 6 hours;
(6) transient value represented by I-134
A > 0.55E10Bq/t (0.15Ci/t), no special instruction, but attention is paid to strengthen monitoring;
(7) transient specific activity expressed as Xe-133
A > 9.25E10Bq/t (2.5Ci/t) or transient specific activity rateAnd Xe-133 > 3.7E10Bq/t (1Ci/t) (3), if there are at least 1 steam generator 5% transferThe heat pipe failed and had to be brought down from maximum operating power to a thermal shutdown at a rate of 30 MW/min.
Step four: the method specifically comprises the following steps of: during the three fuel circulation tests, after each fuel circulation is finished, the irradiation test fuel assembly is subjected to pool-side inspection in a spent fuel pool of the irradiation test nuclear power unit, and whether various irradiation performances after the irradiation test of the CF2 fuel assembly meet the requirements of design indexes is verified.
The pool edge inspection item comprises:
the CF2 fuel assembly all-out-of-stack inspection items comprise:
checking the appearance of the N36 zirconium alloy fuel rod;
n36 zirconium alloy fuel rod length;
n36 zirconium alloy fuel rod diameter;
the thickness of the oxide film on the surface of the N36 zirconium alloy fuel rod;
the spacing between the N36 zirconium alloy fuel rods and the upper and lower pipe seats is equal;
CF2 fuel assembly visual inspection;
CF2 fuel assembly physical dimension inspection;
and (3) checking the surface oxidation film of the fuel rod of the CF2 fuel assembly.
The invention has the beneficial effects that:
the invention provides a novel tracking and monitoring method for the integrity of domestic fuel assemblies, which provides a guarantee for irradiation examination of domestic fuel assemblies in large commercial piles and lays a practical and data foundation for the subsequent research, development, irradiation examination and export of updated domestic fuel assemblies.
In 2013, the reactor-entering irradiation test is started in a refueling core of a No. 10 unit of a second nuclear power plant No. 2 in Qinshan in 6 months, and in 2017, all irradiation test tasks are safely and smoothly completed in 7 months (U2C 12). The actual cumulative burn-up of the CF2 irradiated fuel assemblies reaches between 44259MWd/tU and 44801MWd/tU, reaching and exceeding the design burn-up level.
Drawings
FIG. 1 is a prior art reactor coolant system dissolved hydrogen control curve;
FIG. 2 is an optimized reactor coolant system dissolved hydrogen control curve for a domestic nuclear fuel assembly integrity tracking supervision method of the present invention;
FIG. 3 is a flow chart of a method for tracking and supervising the integrity of a domestic nuclear fuel assembly.
Detailed Description
The invention is further described below with reference to the figures and examples.
As shown in fig. 3, a method for tracking and supervising integrity of a domestic nuclear fuel assembly specifically includes the following steps:
the method comprises the following steps: improving a water quality control method of a reactor primary loop system;
in order to ensure safe and smooth irradiation, the water quality control of a primary loop system is innovated and improved as follows aiming at the actual operation condition of an irradiation examination unit by Qin mountain nuclear power:
to reduce the hydrogen embrittlement corrosion potential of the fuel assembly, the control limit of the dissolved hydrogen content of the primary system was optimized, and the control was adjusted from 25cc/kg to 20cc/kg, see fig. 1 and 2.
Step two: improving the primary system radionuclide analysis method;
after the fuel assembly is irradiated in reactor, the method and mode for measuring radioactive fission nuclide in main system are improved for strengthening the analysis of radioactive fission nuclide in reactor coolant, raising the measurement precision of nuclide and reducing the measurement limit. The chemical laboratory develops a nuclide extraction measurement method, and simultaneously improves a nuclide measurement mode, such as strictly setting the decay time and the retention time of a sample, and increasing the calculation of the nuclide cumulative activity.
The measurement steps are as follows:
1. iodine separation operation
(1) 50ml of main coolant is taken and put into a 200ml separating funnel, 2ml of iodophor is added, shaking is carried out for 1 minute, 5ml of 5% sodium hypochlorite solution is added, shaking is carried out for 1 minute (air release is noticed), standing is carried out for a moment, 6ml of 1mol/L hydroxylamine hydrochloride solution is added, and shaking is carried out for 1 minute.
(2) Add 15ml carbon tetrachloride to the separatory funnel, add 1: 1 concentrated nitric acid until the solution turns yellow, shake for 1 minute, while paying attention to the gassing (gassing was done in a fume hood). Placing the materials into another separating funnel after layering, adding 10ml of carbon tetrachloride and 1ml of 5mol/L sodium nitrite solution into the first separating funnel, shaking for 1 minute, extracting once again, (paying attention to air release), if the iodine is extracted for the second time, the color of the organic phase is still darker, which indicates that the iodine is not extracted completely, adding 10ml of carbon tetrachloride and 1ml of 5mol/L sodium nitrite for re-extraction, until the color of the organic phase is light, discarding the water phase, and leaving the organic phase.
(3) The organic phase was washed twice with equal volume of desalted water, and the aqueous phase was discarded after the phases separated.
(4) Adding 20ml of desalted water into the organic phase, dropwise adding 2ml of 1mol/L sodium hydroxide, adding 2ml of 30% hydrogen peroxide, shaking uniformly for two minutes, back-extracting iodine, standing for layering, removing a carbon tetrachloride layer, transferring the extracted water phase into a 250ml polyethylene bottle, diluting the water phase to 250ml of scale line with the desalted water, and sealing to be tested.
2. Determination of iodine recovery
(1) The main coolant was replaced with demineralized water and the above procedure was repeated to obtain a back extract, after which the aqueous phase was transferred to the main beaker.
(2) The beaker is placed on an electric furnace to be heated slowly, after residual carbon tetrachloride and hydrogen peroxide are burnt out, 2mL of nitric acid solution of 6mol/L is added, 3mL of 1% silver nitrate is immediately dripped to precipitate silver iodide, the silver iodide is heated and boiled for ten minutes and is stirred when not needed, after the precipitate is coagulated, the precipitate is filtered on weighed filter paper in a detachable funnel while the precipitate is hot, then the precipitate is washed three times by hot nitric acid solution of 0.1mol/L, then the precipitate is washed twice by 95% ethanol and ether in sequence, finally the sample is placed in an oven of 100 ℃ to be dried for 20 minutes, the sample is weighed after being cooled, and the chemical recovery rate of the iodine is calculated.
According to the statistical result of chemical sampling analysis, the CF2 fuel assembly is put into a reactor to test that the system has normal release parameters, and the activity of radioactive gas and iodine isotope is far lower than the specified limit value: the maximum value of the total inert gas dose equivalent is 25.40MBq/m3Well below 370000MBq/m3Limit of (2)A value; the maximum value of I-131 equivalent specific activity is 2.95MBq/m3Also much lower than 4400MBq/m3Is measured. Meanwhile, the WANO fuel reliability index (FRI index) obtained by calculation according to the primary loop radiochemical monitoring data and the unit operation data is 0.037, which is the optimal value of the index.
Step three: specially making temporary operation instruction for irradiation examination
During the 208 overhaul loading period, the second power plant No. 2 in Qinshan mountain was loaded with 2 groups of N36 characterized fuel assemblies (N36 assembly is a replacement of the cladding tube and end plug material of 8 fuel rods from M5 alloy to the domestic N36 zirconium alloy in AFA-3G fuel assembly), and these 2 groups of fuel assemblies were irradiated in the reactor for 4 fuel cycles under the reactor operating conditions. During the 209 overhaul charges, 4 sets of autonomous brands of CF2 test fuel assemblies were loaded into the core, during which time the operators were required to strictly adhere to the specifications and related guidelines, with an enhanced supervision of the relevant parameters, in particular the thermal power, the quadrant power tilt ratio QPTR, etc. During the period, the transient times of the unit are reduced as much as possible, and the safe and stable operation of the reactor is kept. When the specific activity of the reactor coolant changes, the operation is executed strictly according to the temporary operation instruction in the table 1.
TABLE 1 temporary run Instructions
Description of the drawings:
(1) these requirements for the transient value (a) must be met individually.
(2) These values are measured when the reactor reaches equilibrium during continuous operation for more than 48 hours and less than 72 hours.
(3) Values measured when equilibrium is reached during steady state reactor operation for more than 48 hours, less than 72 hours.
(4) And if necessary, evaluating the condition of the cladding according to the steady-state working condition of the unit.
Step four: inspecting the tank side after irradiation of the irradiation test fuel assembly;
during the three fuel circulation tests, after each fuel circulation is finished, the irradiation test fuel assembly carries out pool-side inspection on the irradiation test nuclear power unit in a spent fuel pool. So as to verify whether each irradiation performance after the irradiation test of the CF2 fuel assembly meets the requirement of the design index.
The pool edge inspection item comprises:
the CF2 fuel assembly all-out-of-stack inspection items comprise:
checking the appearance of the N36 zirconium alloy fuel rod;
n36 zirconium alloy fuel rod length;
n36 zirconium alloy fuel rod diameter;
the thickness of the oxide film on the surface of the N36 zirconium alloy fuel rod;
the spacing between the N36 zirconium alloy fuel rods and the upper and lower pipe seats, and the like.
CF2 fuel assembly visual inspection;
CF2 fuel assembly physical dimension inspection;
and (3) checking the surface oxidation film of the fuel rod of the CF2 fuel assembly.
The method of carrying out the present invention has been described in detail with reference to the examples, but the present invention is not limited to the examples described above, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art. The prior art can be adopted for the content which is not described in detail in the specification of the invention.