CN110688685A - Method for calculating pressure and temperature limit curve of reactor pressure vessel based on 2000 edition and former edition RCCM (national center of Care Commission) standard - Google Patents
Method for calculating pressure and temperature limit curve of reactor pressure vessel based on 2000 edition and former edition RCCM (national center of Care Commission) standard Download PDFInfo
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Abstract
The invention relates to a method for calculating a pressure-temperature limit curve of a reactor pressure vessel based on the RCCM specification of the 2000 edition and the former edition, which comprises the following steps of 1, determining a calculation input parameter of the pressure-temperature limit curve of the reactor pressure vessel; 2. determining a size of a defect on a reactor pressure vessel; 3. calculating the temperature and the thermal stress of each position along the wall thickness direction of the pressure container at each moment in the cooling process; 4. analyzing and determining the most dangerous defect position and the ductile-brittle transition temperature of the material at the defect position in the reactor cooling process; 5. calculating the allowable pressure at each moment in the cooling process; 6. calculating the temperature and the thermal stress of each position along the wall thickness direction of the pressure vessel at each moment in the temperature rise process; 7. analyzing and determining the most dangerous defect position and the ductile-brittle transition temperature of the material at the defect position in the reactor heating process; 8. and calculating the allowable pressure at each moment in the temperature rising process. The invention effectively meets the A-level criterion in the RCCM specification appendix ZG rapid fracture resistance analysis of the version 2000 and the previous version, and fills the blank of the prior art.
Description
Technical Field
The invention belongs to the technical field of structural integrity analysis of reactor pressure vessels, and particularly relates to a method for calculating a pressure-temperature limit curve of a reactor pressure vessel based on the RCCM specification of the 2000 edition and the former edition.
Background
The reactor pressure vessel is a nuclear safety first-level component, and in the service process, due to the influence of neutron irradiation, the material performance will gradually deteriorate, specifically, the strength is increased, and the plasticity and toughness are reduced. In order to prevent brittle fracture, the temperature and pressure in the pressure vessel of the nuclear power plant must be controlled within the range specified by the limit curve (P-T curve) during the start-stop process of the nuclear power plant.
At present, a considerable number of nuclear power units are designed and built according to RCCM specifications of 2000 edition and previous editions in China. Unfortunately, the RCCM specification does not provide a detailed pressure temperature limit curve calculation method and flow, and only mentions in appendix ZG "rapid fracture resistance analysis" that the user can establish a pressure temperature limit curve according to class a fracture criteria. Due to the difference of knowledge levels of the standard users and the difference of understanding of the standard, different standard users may calculate different pressure and temperature limit curves, and potential safety hazards are brought to the operation of the nuclear power unit.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for calculating a pressure-temperature limit curve of a reactor pressure vessel based on the RCCM specification of 2000 edition and the former edition.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a method for calculating a pressure-temperature limit curve of a reactor pressure vessel based on the RCCM specification of version 2000 and the previous version comprises the following steps:
determining a pressure and temperature limit value curve of a reactor pressure vessel to calculate input parameters;
determining the size of the defect on the reactor pressure vessel;
calculating the temperature and the thermal stress of each position along the wall thickness direction of the pressure container at each moment in the cooling process;
analyzing and determining the most dangerous defect position and the ductile-brittle transition temperature of the material at the defect position in the reactor cooling process;
calculating the allowable pressure at each moment in the cooling process;
step six, calculating the temperature and the thermal stress of each position along the wall thickness direction of the pressure vessel at each moment in the temperature rising process;
analyzing and determining the most dangerous defect position and the ductile-brittle transition temperature of the material at the defect position in the reactor heating process;
and (eight) calculating the allowable pressure at each moment in the temperature rising process.
According to a further implementation aspect of the invention, the input parameters of the calculation in the step (one) mainly comprise the parameters of the radius of the reactor pressure vessel, the wall thickness, the physical property parameters of the material, the fracture toughness and the like.
According to a further aspect of the invention, step (two) specifically includes sizing the crack defects for axial semi-elliptical surface crack defects present on the reactor pressure vessel according to a look-up table of hypothetical defect sizes in the RCCM specification and a wall thickness of the reactor pressure vessel. The dimensions include defect depth and defect length.
According to a further aspect of the present invention, in step (three), the metal temperature and the thermal stress at each position of the reactor pressure vessel along the wall thickness direction at each moment during the temperature reduction process are calculated by using finite element software or other methods.
According to a further implementation aspect of the present invention, step (iv) specifically includes:
4.1) when the reactor is in a temperature reduction process, the inner wall of the pressure vessel bears tensile stress, the outer wall bears compressive stress, and due to neutron irradiation, the fracture toughness of the reactor pressure vessel material is gradually reduced from the inner wall to the outer wall along the wall thickness direction, so that the defect is the most dangerous condition at the position of the inner surface of the vessel in the temperature reduction process;
4.2) after determining the defect position, calculating the ductile-brittle transition temperature RT of the defect position by adopting a method recommended by RCCM specification or other conservative methodsNDTThe calculation formula is as follows:
RTNDT=RTNDT(i)+ΔRTNDT(4.1)
wherein, RTNDT(i)Δ RT is the initial ductile-to-brittle transition temperatureNDTFor the ductile-brittle transition temperature increment, the calculation formula is as follows
ΔRTNDT=[22+556(%Cu-0.08)+2778(%P-0.008)](f)1/2(4.2)
Wherein, the percent Cu is the percentage content of copper element in the reactor pressure vessel material, when the percent Cu is less than 0.08, the value of the percent Cu is 0.08; the% P is the percentage content of phosphorus element in the reactor pressure vessel material, when the% P is less than 0.008, the value of the% P is 0.008; f is fast neutron fluence. All the parameters can be found in the relevant technical data of the nuclear power plant.
According to a further implementation aspect of the invention, the step (v) specifically includes:
5.1) setting the coolant temperature in the reactor pressure vessel at a certain moment to TwThe temperature of the metal material at the defect position is T, and the reference fracture toughness K of the reactor pressure vessel material at the defect position can be calculated according to the formula 5.1IR:
Wherein T is the metal temperature of the defective position of the pressure vessel.
5.2) calculating the stress intensity factor K caused by the thermal stress according to the thermal stress obtained in the step (three)ItThe specific calculation method refers to the RCCM specification appendix ZG 6000 section or other data;
5.3) calculating the allowable pressure P according to the formula 5.2:
wherein, KImIs the stress intensity factor caused by pressure. In general, the calculation of the pressure-temperature limit curve uses a linear elastomechanical analysis model, so KImAnd the pressure P. Equation 5.2 is from RCCM specification annex ZG fragmentation analysis criteria a:
2KIm+KIt=KIR(5.3) solving the formula 5.2 to obtain the temperature T of the coolantwThe corresponding allowable pressure P;
5.4) repeating the steps 5.1-5.3, solving the allowable pressure at each moment in the cooling process, and comparing the temperature-pressure pair (T) at each momentwAnd P) are connected into a line to form a pressure and temperature limit curve in the cooling process.
According to a further aspect of the present invention, in the step (six), the metal temperature and the thermal stress at each position of the reactor pressure vessel along the wall thickness direction at each time during the temperature raising process are calculated by using finite element software or other methods.
According to a further implementation aspect of the invention, the step (seven) specifically comprises:
7.1) when the reactor is in a temperature rise process, the inner wall of the pressure vessel bears compressive stress, the outer wall bears tensile stress, and due to neutron irradiation, the fracture toughness of the reactor pressure vessel material is gradually reduced from the inner wall to the outer wall along the wall thickness direction, so that the defect is located at the inner surface position or the outer surface of the vessel possibly in the most dangerous condition, the defect located at the inner surface position and the outer surface of the vessel are respectively calculated when a pressure temperature limit curve is calculated, then allowable pressure under two conditions at each moment is calculated, and the minimum value is taken as the final allowable pressure;
7.2) after determining the defect position, calculating the ductile-brittle transition temperature RT of the defect position by adopting a method recommended by RCCM specification or other conservative methodsNDTThe calculation formula is as follows:
RTNDT=RTNDT(i)+ΔRTNDT(4.1)
wherein, RTNDT(i)The initial ductile-brittle transition temperature. Δ RTNDTFor ductile-brittle transition temperature increment, the calculation formula is as follows:
ΔRTNDT=[22+556(%Cu-0.08)+2778(%P-0.008)](f)1/2(4.2)
wherein, the percent Cu is the percentage content of copper element in the reactor pressure vessel material, when the percent Cu is less than 0.08, the value of the percent Cu is 0.08; the% P is the percentage content of phosphorus element in the reactor pressure vessel material, when the% P is less than 0.008, the value of the% P is 0.008; f is fast neutron fluence;
7.3) respectively calculating the ductile-brittle transition temperature RT corresponding to the inner surface defects according to the step (7.2)NDT_InDuctile-brittle transition temperature RT corresponding to outer surface defectsNDT_Out。
According to a further implementation aspect of the invention, step (eight) specifically comprises:
8.1) for a certain time the temperature of the coolant in the reactor pressure vessel is Tw;
8.2) calculating the allowable pressure P corresponding to the defect at the position of the inner surfaceInThe method specifically comprises the following steps:
8.2.1) the temperature of the metal material at the defect position is T, and the reference fracture toughness K of the reactor pressure vessel material at the defect position can be calculated according to the formula 5.1IR:
Wherein T is the metal temperature of the defect position of the pressure vessel;
8.2.2) calculating the stress intensity factor K caused by the thermal stress according to the thermal stress obtained in the step (six)ItThe specific calculation method refers to RCCM gaugeSection ZG 6000 or other data in the model appendix;
8.2.3) calculating the allowable pressure P according to equation 5.2:
wherein, KImFor stress-induced stress intensity factors, equation 5.2 is derived from RCCM specification annex ZG fracture analysis criteria a:
2KIm+KIt=KIR(5.3) solving the formula 5.2 to obtain the temperature T of the coolantwThe allowable pressure value is the allowable pressure P corresponding to the inner surface defectInA value;
8.3) calculating the allowable pressure P corresponding to the defect at the outer surface positionOutThe method specifically comprises the following steps:
8.3.1) the temperature of the metal material at the defect position is T, and the reference fracture toughness K of the reactor pressure vessel material at the defect position can be calculated according to the formula 5.1IR:
8.3.2) calculating the stress intensity factor K caused by the thermal stress according to the thermal stress obtained in the step (six)ItThe specific calculation method refers to the RCCM specification appendix ZG 6000 section or other data;
8.3.3) calculating the allowable pressure P according to the formula 5.2, wherein the allowable pressure value is the allowable pressure P corresponding to the outer surface defectInA value;
8.4) taking PInAnd POutThe smaller in between is the final allowable pressure P;
8.5) repeating the steps (8.1) to (8.4), solving the allowable pressure at each moment in the temperature rising process, and combining the temperature-pressure at each moment with the temperature-pressure pair [ T [ [ T ]w,P]The connecting line constitutes the pressure-temperature limit curve of the warming process.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:
the method for calculating the pressure-temperature limit curve of the reactor pressure vessel suitable for the RCCM specification of the 2000 edition and the previous edition analyzes and determines the most dangerous position of the hypothetical defect, defines the calculation and analysis flow of the allowable pressure in the heating process and the cooling process, and the calculated pressure-temperature limit curve can effectively meet the A-level criterion in the ZG anti-rapid fracture analysis of the RCCM specification annex of the 2000 edition and the previous edition and fills the blank in the prior art.
Drawings
FIG. 1 is a flow chart of the pressure temperature limit curve calculation of the present invention based on the RCCM specification version 2000 and earlier.
FIG. 2 is a schematic diagram of a reactor pressure vessel defect;
in the figure, t is the container wall thickness; r is the inner radius of the container; a is the defect depth; and 2b is the defect length.
FIG. 3 is a two-dimensional axisymmetric finite element analysis model of a reactor pressure vessel.
Fig. 4 is a diagram illustrating a pressure-temperature limit curve of a reactor pressure vessel during a temperature-reducing process.
FIG. 5 is a graphical illustration of a temperature limit curve for a reactor pressure vessel during ramp up.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments.
The flow chart of the calculation of the pressure-temperature limit curve for a reactor pressure vessel constructed based on the RCCM specification version 2000 is shown in fig. 1, and the specific method comprises the following steps:
(one) determining the input parameters for the calculation of the temperature limit curve of the reactor pressure vessel
The parent metal material of the reactor pressure vessel is 16MND5, the inner radius of the vessel is 1994.5mm, and the wall thickness of the parent metal is 200 mm; the material grade of the overlaying layer is E308L/309L, and the wall thickness of the overlaying layer is 7 mm.
The initial ductile-brittle transition temperature of the parent metal of the reactor pressure vessel is RTNDT(i)Is-12 ℃. The percentage content of copper element in the parent metal is 0.08, and the percentage content of phosphorus element is 0.008.
And calculating pressure and temperature limit curves corresponding to the temperature rising process and the temperature lowering process of the reactor pressure vessel. The temperature change rate in the temperature rising and reducing processes is set to be 55 ℃/h.
Step (two) determining the defect size
The reactor pressure vessel exhibited an axial semi-elliptical surface flaw as shown in figure 2.
The hypothetical defect sizes shown in Table 1 are given in the RCCM specification version 2000
TABLE 1 hypothetical Defect sizes
Wall thickness of container | Depth of defect | Length of defect | |
< | 25mm | 150mm | |
100~300mm | 1/4 container thickness | 1.5 Container thickness | |
>300mm | 75mm | 450mm |
According to the step (I) where the wall thickness of the base material is 200mm and Table 1, the defect depth (i.e., a) is determined to be 50mm and the defect length (i.e., 2b) is determined to be 300 mm.
And (III) calculating the temperature and the thermal stress of each position along the wall thickness direction of the pressure container at each moment in the cooling process, and specifically comprising the following steps of:
3.1) setting the temperature of the coolant in the reactor pressure vessel to be reduced from 315 ℃ to 5 ℃, wherein the temperature reduction rate is 55 ℃/h.
And 3.2) calculating the temperature and the thermal stress at each position along the wall thickness direction of the pressure container at each moment in the cooling process by adopting ANSYS software. The analytical model is a 2-dimensional axisymmetric model, as shown in FIG. 3. Thermal analysis assumes infinite heat exchange between the inner surface of the vessel and the coolant and thermal insulation of the outer surface. And during structural analysis, the axial degree of freedom of the lower end of the analysis model is restrained. The results are shown in tables 2 and 3, where x is a normalized positional parameter, x ═ 0 indicates the container inner surface position (weld overlay and base material interface), and x ═ 1 indicates the container outer surface position.
TABLE 2 Metal temperature at each point along the wall thickness of the pressure vessel at each time of the cooling process
TABLE 3 circumferential stress at various points along the wall thickness direction of the pressure vessel at various times during the cooling process
And (IV) analyzing and determining the most dangerous defect position in the reactor cooling process and the ductile-brittle transition temperature of the material at the defect position. The method specifically comprises the following steps:
4.1) for the cooling process, on the one hand, when the reactor is in the cooling process, the inner wall of the pressure vessel bears tensile stress and the outer wall bears compressive stress. On the other hand, due to neutron irradiation, the fracture toughness of the reactor pressure vessel material gradually decreases from the inner wall to the outer wall in the wall thickness direction. It is therefore the most dangerous situation for the cooling process that the defects are located at the inner surface of the container.
4.2) determining the defect position, wherein x is 0.25, and calculating the ductile-brittle transition temperature RT of the defect position by adopting a method recommended by the RCCM specification or other conservative methodsNDT
RTNDT=RTNDT(i)+ΔRTNDT(4.1)
Wherein, RTNDT(i)The initial ductile-brittle transition temperature. Δ RTNDTFor ductile-brittle transition temperature increment, the calculation formula is as follows:
ΔRTNDT=[22+556(%Cu-0.08)+2778(%P-0.008)](f)1/2(4.2)
wherein, the percent Cu is the percentage content of copper element in the reactor pressure vessel material, when the percent Cu is less than 0.08, the value of the percent Cu is 0.08; the% P is the percentage content of phosphorus element in the reactor pressure vessel material, when the% P is less than 0.008, the value of the% P is 0.008; f is fast neutron fluence. All the parameters can be found in the relevant technical data of the nuclear power plant.
Finally, RTNDT=RTNDT(i)+ΔRTNDT=-12℃+49℃=37℃。
And (V) calculating the allowable pressure at each moment in the cooling process. Taking 20291 th second in the cooling process as an example, the allowable pressure is calculated. At this point, the coolant temperature within the reactor pressure vessel has decreased to 5 ℃.
The method specifically comprises the following steps:
5.1) setting the coolant temperature at a certain time as TwThe temperature of the metal material at the defect site is T. The reference fracture toughness K of the reactor pressure vessel material at the defect position can be calculated according to the formula 5.1IR:
Wherein T is the metal temperature of the defective position of the pressure vessel.
According to table 2, the temperature of the metal material at the defect site (x ═ 0.25) at this time was 18.6 ℃. The reference fracture toughness K of the metal material at this point in time is determined according to equation 5.1IRHas a value of
5.2) calculating the stress intensity factor K caused by the thermal stress according to the thermal stress obtained in the step (three)ItThe specific calculation method refers to an influence function method recommended by RCCM specification annex ZG 6000 section to calculate and obtain a stress intensity factor K caused by thermal stressItIs composed of
5.3) calculating the allowable pressure P according to the formula 5.2:
wherein, KImIs the stress intensity factor caused by pressure. In general, the calculation of the pressure-temperature limit curve uses a linear elastomechanical analysis model, so KImAnd the pressure P. Equation 5.2 is from RCCM specification annex ZG fragmentation analysis criteria a:
2KIm+KIt=KIR(5.3) solving the formula 5.2 to obtain the temperature T of the coolantwThe corresponding allowable pressure P is 2.8 MPa.
And 5.4) repeating the step 5.1-5.3, and solving the allowable pressure at each moment in the cooling process. Temperature-pressure pairs (T) at each momentwAnd P) are connected into a line to form a pressure-temperature limit curve in the cooling process, and the result is shown in FIG. 4.
And (VI) calculating the temperature and the thermal stress of each position along the wall thickness direction of the pressure vessel at each moment in the temperature rising process. The method specifically comprises the following steps:
6.1) setting the temperature of the coolant in the reactor pressure vessel to rise from 5 ℃ to 315 ℃ at the rate of 55 ℃/h.
6.2) calculating the temperature and the thermal stress at each time of the heating process at each position along the wall thickness direction of the pressure vessel by adopting ANSYS software. The results are shown in tables 4 and 5.
TABLE 4 Metal temperature at various points along the wall thickness direction of the pressure vessel at various times during the heating process
TABLE 5 circumferential stress at various points along the wall thickness direction of the pressure vessel at various times during the heating process
And (seventhly), analyzing and determining the most dangerous defect position in the reactor heating process and the reference ductile-brittle transition temperature of the material at the defect position. The method specifically comprises the following steps:
7.1) when the reactor is in the temperature rising process, the inner wall of the pressure vessel bears the pressure stress, and the outer wall bears the tensile stress. Due to neutron irradiation, the fracture toughness of the reactor pressure vessel material is gradually reduced from the inner wall to the outer wall along the wall thickness direction. It is therefore likely that the defect will be located at either the inner surface or the outer surface of the vessel, which is the most dangerous situation, and it is necessary to calculate the pressure temperature limit curve assuming that the defect is located at both the inner surface and the outer surface of the vessel, respectively.
7.2) internal surface defect site (x ═ 0.25) withstands a neutron fluence of 5 × 1019n/cm2. The outer surface defect site (x ═ 0.75) withstood a neutron fluence of 1.94×1019n/cm2. Respectively calculating the ductile-brittle transition temperature RT corresponding to the inner surface defects according to the formulas 4.1 and 4.2NDT_InIs a ductile-brittle transition temperature RT corresponding to 37 ℃ and outer surface defectsNDT_OutThe temperature was 18.6 ℃.
And (eight) calculating the allowable pressure at each moment in the temperature rising process. Taking 20291 th second in the temperature raising process as an example, the allowable pressure is calculated. At this point, the coolant temperature within the reactor pressure vessel has increased to 315 ℃.
The method specifically comprises the following steps:
8.1) the defect is located at the inner surface position. From table 4, the temperature of the metal material at the defect position (x ═ 0.25) at this time was 295 ℃. The reference fracture toughness K of the metal material at this point in time is determined according to equation 5.1IRHas a value of
8.2) the stress intensity factor K corresponding to the internal surface defect caused by the thermal stress can be calculated by referring to the influence function method recommended by the RCCM specification appendix ZG 6000 sectionItIs composed of(KItNegative because the inner wall of the vessel is subjected to compressive stress during the heating process).
8.3) calculating the allowable pressure P corresponding to the inner surface defect according to the formula 5.2InIs 26.8 MPa.
8.4) the defect is located at the outer surface position. According to table 4, the temperature of the metal material at the defect position (x ═ 0.75) at this time was 278 ℃. The reference fracture toughness K of the metal material at this point in time is determined according to equation 5.1IRHas a value of
8.5) the stress intensity factor K corresponding to the external surface defect caused by the thermal stress can be calculated by referring to the influence function method recommended by the RCCM specification appendix ZG 6000 sectionItIs composed of
8.6) calculating the allowable pressure P corresponding to the outer surface defect according to the formula 5.2OutIs 22.8 MPa.
8.7) allowable pressure P is PInAnd POutThe smaller in between, i.e., 22.8 MPa.
8.1) repeating the step 8.1-8.8, and solving the allowable pressure at each moment in the temperature rising process. Temperature-pressure pairs [ T ] at each momentw,P]The line connected constitutes the pressure-temperature limit curve of the warming process, and the specific result is shown in fig. 5.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (9)
1. A method for calculating a pressure-temperature limit curve of a reactor pressure vessel based on the RCCM specification of version 2000 and the previous version is characterized by comprising the following steps of:
determining a pressure and temperature limit value curve of a reactor pressure vessel to calculate input parameters;
determining the size of the defect on the reactor pressure vessel;
calculating the temperature and the thermal stress of each position along the wall thickness direction of the pressure container at each moment in the cooling process;
analyzing and determining the most dangerous defect position and the ductile-brittle transition temperature of the material at the defect position in the reactor cooling process;
calculating the allowable pressure at each moment in the cooling process;
step six, calculating the temperature and the thermal stress of each position along the wall thickness direction of the pressure vessel at each moment in the temperature rising process;
analyzing and determining the most dangerous defect position and the ductile-brittle transition temperature of the material at the defect position in the reactor heating process;
and (eight) calculating the allowable pressure at each moment in the temperature rising process.
2. The method of calculating a reactor pressure vessel pressure temperature limit curve based on release 2000 and a previous release RCCM specification of claim 1, wherein: the input parameters in the step (I) comprise the radius of the reactor pressure vessel, the wall thickness, the physical property parameters of the material and the fracture toughness.
3. The method of calculating a reactor pressure vessel pressure temperature limit curve based on release 2000 and a previous release RCCM specification of claim 1, wherein: and (b) specifically determining the size of the crack defect on the axial semi-elliptical surface crack defect existing on the reactor pressure vessel according to a hypothetical defect size comparison table in the RCCM specification and the wall thickness of the reactor pressure vessel.
4. The method of calculating a reactor pressure vessel pressure temperature limit curve based on release 2000 and a previous release RCCM specification of claim 1, wherein: and (III) calculating the metal temperature and the thermal stress of the reactor pressure vessel at each position along the wall thickness direction at each moment in the cooling process by using finite element software or other methods.
5. The method of calculating a reactor pressure vessel pressure temperature limit curve based on release 2000 and a previous release RCCM specification of claim 1, wherein: the step (IV) specifically comprises the following steps:
4.1) when the reactor is in a temperature reduction process, the inner wall of the pressure vessel bears tensile stress, the outer wall bears compressive stress, and due to neutron irradiation, the fracture toughness of the reactor pressure vessel material is gradually reduced from the inner wall to the outer wall along the wall thickness direction, so that the defect is the most dangerous condition at the position of the inner surface of the vessel in the temperature reduction process;
4.2) after determining the defect position, calculating the defect by adopting a method recommended by the RCCM specification or other conservative methodsDuctile-brittle transition temperature RT of trap sitesNDTThe calculation formula is as follows:
RTNDT=RTNDT(i)+ΔRTNDT(4.1)
wherein, RTNDT(i)Δ RT is the initial ductile-to-brittle transition temperatureNDTFor ductile-brittle transition temperature increment, the calculation formula is as follows:
ΔRTNDT=[22+556(%Cu-0.08)+2778(%P-0.008)](f)1/2(4.2)
wherein, the percent Cu is the percentage content of copper element in the reactor pressure vessel material, when the percent Cu is less than 0.08, the value of the percent Cu is 0.08; the% P is the percentage content of phosphorus element in the reactor pressure vessel material, when the% P is less than 0.008, the value of the% P is 0.008; f is fast neutron fluence.
6. The method of calculating a reactor pressure vessel pressure temperature limit curve based on release 2000 and a previous release RCCM specification of claim 1, wherein: the step (V) specifically comprises the following steps:
5.1) setting the coolant temperature in the reactor pressure vessel at a certain moment to TwThe temperature of the metal material at the defect position is T, and the reference fracture toughness K of the reactor pressure vessel material at the defect position can be calculated according to the formula 5.1IR:
Wherein T is the metal temperature of the defect position of the pressure vessel;
5.2) calculating the stress intensity factor K caused by the thermal stress according to the thermal stress obtained in the step (three)ItThe specific calculation method refers to the RCCM specification appendix ZG 6000 section or other data;
5.3) calculating the allowable pressure P according to the formula 5.2:
wherein, KImFor pressure introductionFrom the stress intensity factor, equation 5.2 comes from the RCCM specification annex ZG fracture analysis criteria A:
2KIm+KIt=KIR(5.3)
solving the formula 5.2 to obtain the temperature T of the coolantwThe corresponding allowable pressure P;
5.4) repeating the steps 5.1-5.3, solving the allowable pressure at each moment in the cooling process, and comparing the temperature-pressure pair (T) at each momentwAnd P) are connected into a line to form a pressure and temperature limit curve in the cooling process.
7. The method of calculating a reactor pressure vessel pressure temperature limit curve based on release 2000 and a previous release RCCM specification of claim 1, wherein: and (sixthly), calculating the metal temperature and the thermal stress of the reactor pressure vessel at each position along the wall thickness direction at each moment in the temperature rising process by using finite element software or other methods.
8. The method of calculating a reactor pressure vessel pressure temperature limit curve based on release 2000 and a previous release RCCM specification of claim 1, wherein: the step (VII) specifically comprises the following steps:
7.1) when the reactor is in a temperature rise process, the inner wall of the pressure vessel bears compressive stress, the outer wall bears tensile stress, and due to neutron irradiation, the fracture toughness of the reactor pressure vessel material is gradually reduced from the inner wall to the outer wall along the wall thickness direction, so that the defect is possibly the most dangerous condition at the inner surface position or the outer surface of the vessel, and the defect is required to be calculated at the inner surface position and the outer surface of the vessel respectively when a pressure temperature limit curve is calculated;
7.2) after determining the defect position, calculating the ductile-brittle transition temperature RT of the defect position by adopting a method recommended by RCCM specification or other conservative methodsNDTThe calculation formula is as follows:
RTNDT=RTNDT(i)+ΔRTNDT(4.1)
wherein, RTNDT(i)The initial ductile-brittle transition temperature. Δ RTNDTFor the increase of the ductile-brittle transition temperature,the calculation formula is as follows:
ΔRTNDT=[22+556(%Cu-0.08)+2778(%P-0.008)](f)1/2(4.2)
wherein, the percent Cu is the percentage content of copper element in the reactor pressure vessel material, when the percent Cu is less than 0.08, the value of the percent Cu is 0.08; the% P is the percentage content of phosphorus element in the reactor pressure vessel material, when the% P is less than 0.008, the value of the% P is 0.008; f is fast neutron fluence;
7.3) respectively calculating the ductile-brittle transition temperature RT corresponding to the inner surface defects according to the step (7.2)NDT_InDuctile-brittle transition temperature RT corresponding to outer surface defectsNDT_Out。
9. The method of calculating a reactor pressure vessel pressure temperature limit curve based on release 2000 and a previous release RCCM specification of claim 1, wherein: the step (eight) specifically comprises:
8.1) for a certain time the temperature of the coolant in the reactor pressure vessel is Tw;
8.2) calculating the allowable pressure P corresponding to the defect at the position of the inner surfaceInThe method specifically comprises the following steps:
8.2.1) the temperature of the metal material at the defect position is T, and the reference fracture toughness K of the reactor pressure vessel material at the defect position can be calculated according to the formula 5.1IR:
Wherein T is the metal temperature of the defect position of the pressure vessel;
8.2.2) calculating the stress intensity factor K caused by the thermal stress according to the thermal stress obtained in the step (six)ItThe specific calculation method refers to the RCCM specification appendix ZG 6000 section or other data;
8.2.3) calculating the allowable pressure P according to equation 5.2:
wherein, KImFor stress-induced stress intensity factors, equation 5.2 is derived from RCCM specification annex ZG fracture analysis criteria a:
2KIm+KIt=KIR(5.3)
solving the formula 5.2 to obtain the temperature T of the coolantwThe allowable pressure value is the allowable pressure P corresponding to the inner surface defectInA value;
8.3) calculating the allowable pressure P corresponding to the defect at the outer surface positionOutThe method specifically comprises the following steps:
8.3.1) the temperature of the metal material at the defect position is T, and the reference fracture toughness K of the reactor pressure vessel material at the defect position can be calculated according to the formula 5.1IR:
8.3.2) calculating the stress intensity factor K caused by the thermal stress according to the thermal stress obtained in the step (six)ItThe specific calculation method refers to the RCCM specification appendix ZG 6000 section or other data;
8.3.3) calculating the allowable pressure P according to the formula 5.2, wherein the allowable pressure value is the allowable pressure P corresponding to the outer surface defectInA value;
8.4) taking PInAnd POutThe smaller in between is the final allowable pressure P;
8.5) repeating the steps (8.1) to (8.4), solving the allowable pressure at each moment in the temperature rising process, and combining the temperature-pressure at each moment with the pressure (T)wAnd P) are connected into a line to form a pressure-temperature limit curve of the temperature rise process.
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