CN103852094A - Method for judging influences of transient high temperature on meter - Google Patents

Abstract

The invention belongs to the technical field of nuclear power, and discloses a method for judging influences of transient high temperature on a meter. On the basis of a heat transfer principle, heat stagnation time is determined, then transient temperature rise time t is determined, and accordingly influences of hydrogen explosion on the meter are judged by comparison of meter heat stagnation time with transient temperature duration in a containment vessel and availability of the meter under serious accident conditions is judged. By the adoption of the method, influences of transient temperature rise under the serious accident conditions on the meter can be judged without related tests carried out on the meter, meanwhile, the method is also suitable for other meters of different sizes, what is needed is to figure out materials of a meter case and the installation position, away from the case, of an electronic component, the heat stagnation time of the meter can be obtained through corresponding calculations, test cost is greatly saved, and the method is used for effectively judging the influences of the transient high temperature on the meter under the serious accident conditions.

Description

The determination methods of a kind of transient high temperature on instrument impact

Technical field

The invention belongs to nuclear power technology field, be specifically related to the definite technology of a kind of transient high temperature on instrument impact.

Background technology

Along with the generation of Three Mile Island accident and Fukushima event, countries in the world have all been strengthened the research dynamics to major accident and have been formulated corresponding severe accident relieving measure, wherein explicitly call in order to submit necessary information to operator, part still needs available under major accident for the instrument of measuring important parameter, continue to carry out its measurement function.

Under major accident condition, in core melt progression, the water and steam of interior other metal material of zirconium cladding material and heap and high temperature occurs can produce a large amount of hydrogen after violent chemical reaction, when the concentration of these hydrogen reaches after certain proportion, under applicable external condition, may cause blast, have the possibility of hydrogen detonation.Temperature in containment can raise and then fall after rise rapidly within the extremely short time in this case, or continue to raise, fall after rise repeatedly, form the environmental baseline that a transient temperature raises, although the temperature of this transient state raises, the duration is very short, but its peak temperature is very high, mxm. can reach thousands of degrees Celsius.

Because the instrument that power plant is used is now all the qualification through benchmark accident, do not pass through the qualification of the quick-fried condition of similar hydrogen, and for build and built power plant do not possess yet and instrument re-started to the condition of testing under relevant major accident, therefore how to judge that whether instrument can be affected under the transient high temperature environmental baseline of the quick-fried generation of hydrogen is a crucial technical matters, the research of determination methods is mainly to concentrate on by test to obtain corresponding conclusion at present, but because test condition is difficult to imitate, the problems such as test cost is huge are made slow progress at present, therefore adopt a kind of new method to judge that transient high temperature is very important on the impact of instrument.

Summary of the invention

The object of the present invention is to provide a kind of simple, reliable, the determination methods of the transient high temperature that can improve npp safety and economy simultaneously on instrument impact.

Realize technical scheme of the present invention as follows:

The determination methods of transient high temperature on instrument impact, the method comprises the steps:

1) determine instrument heat stagnation time τ, heat is delivered to the time of internal electrical components from gauge external high temperature, and its method is as follows:

A) utilize following formula to determine complete wet several Bi of meter body

$\mathrm{Bi}=\frac{h}{\mathrm{\λR}}$

Wherein: h is convection transfer rate, λ is meter case coefficient of heat conductivity, and R is the cylindrical radius of meter case;

B) the complete wet several Bi by meter body with

in nomograph, draw

functional value, utilizes following formula to draw final excess enthalpy temperature θ _wwith center excess enthalpy temperature θ _mratio;

$\frac{{\mathrm{\θ}}_w}{{\mathrm{\θ}}_m}=f(\mathrm{Bi},\frac{r}{R})$

Wherein, r is the distance of electronic unit apart from outside surface, θ _wfor final excess enthalpy temperature, θ _mcentered by excess enthalpy temperature;

C) utilize following formula to obtain the final excess enthalpy temperature θ of instrument _wwith initial excess enthalpy temperature θ ₀ratio;

$\frac{{\mathrm{\θ}}_w}{{\mathrm{\θ}}_0}=\frac{t_{\max }-t_{\∞}}{t_0-t_{\∞}}$

Wherein, t _maxthe maximum temperature that while qualification for instrument, its electronic unit bears, t _∞environment maximum temperature, t ₀for instrument initial temperature;

D) utilize following formula to determine center excess enthalpy temperature θ _mwith initial excess enthalpy temperature θ ₀ratio;

$\frac{{\mathrm{\θ}}_m}{{\mathrm{\θ}}_0}=\frac{{\mathrm{\θ}}_w}{{\mathrm{\θ}}_0}/\frac{{\mathrm{\θ}}_{\mathrm{\θ}}}{{\mathrm{\θ}}_m}$

E) the complete wet several Bi by meter body with

in nomograph, check in

utilize following formula to draw heat stagnation time τ;

$\mathrm{\&tau;}=f(\mathrm{Bi},\frac{{\mathrm{\&theta;}}_m}{{\mathrm{\&theta;}}_0})\frac{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA00002544942200011.png"\; state="\{\{state\}\}">R</figure-callout>}}^2}{\mathrm{\&alpha;}}$

Wherein, a is thermal diffusivity;

2) determine the transient temperature time t that raises, the moment that transient temperature raises rises, and recovers the normal moment to transient temperature, time apart between these two moment;

3) by the transient temperature duration in instrument heat stagnation time and containment on recently judging the quick-fried impact on instrument of hydrogen;

If τ is more than or equal to t, the temperature of transient state raises does not affect instrument, can not affect the function of instrument;

If τ is less than t, the temperature of transient state raises and may impact instrument, and instrument exists disabled risk.

The obtained beneficial effect of the present invention is as follows: the principle of transmitting based on heat, by determining that the heat stagnation time judges whether the transient high temperature of hydrogen detonation burning generation can exert an influence to the performance of instrument, pass judgment on the availability of instrument under major accident condition, adopt after this method, the test that does not need the instrument to be correlated with just can be judged the impact on instrument of transient temperature rise under major accident, the method has versatility for the instrument of different size simultaneously, as long as the material of clear and definite meter case and electronic unit are apart from the installation site of shell, just can be by calculating accordingly the heat stagnation time of instrument, test funds are greatly saved, that one judges under major accident condition, the effective ways of transient high temperature on instrument impact judgement.

Brief description of the drawings

Fig. 1 is the structural drawing of pressure inverting instruments and meters;

Fig. 2 is the interior temperature variation of containment under a kind of typical major accident condition;

In figure: 1. cylindrical stainless steel casing; 2. internal electrical components.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.

The structural drawing of pressure inverting instrument as shown in Figure 1, pressure unit is to be made up of stainless steel casing and internal electrical components, wherein the high temperature of the quick-fried generation of hydrogen is mainly the electronic unit affecting in involucrum.

According to the principle of thermal conduction study, the heat transfer model of instrument is reduced to endless cylinder here and considers.The R marking in Fig. 1 is cylindrical radius, and r is the distance of electronic unit apart from outside surface.

1) determine instrument heat stagnation time τ, heat is delivered to the time of internal electrical components from gauge external, and its method is as follows:

A) utilize following formula to determine complete wet several Bi of meter body

$\mathrm{Bi}=\frac{h}{\mathrm{\&lambda;R}}$

Wherein: h is convection transfer rate, λ is meter case coefficient of heat conductivity, and R is the cylindrical radius of meter case, and h and λ can be according to the acquisitions of tabling look-up of different convection types and meter case material.

B) the complete wet several Bi by meter body with

in nomograph, draw

functional value, utilizes following formula to draw final excess enthalpy temperature θ _wwith center excess enthalpy temperature θ _mratio;

$\frac{{\mathrm{\&theta;}}_w}{{\mathrm{\&theta;}}_m}=f(\mathrm{Bi},\frac{r}{R})$

Wherein, r is the distance of electronic unit apart from outside surface, θ _wfor final excess enthalpy temperature, θ _mcentered by excess enthalpy temperature;

C) utilize following formula to obtain the final excess enthalpy temperature θ of instrument _wwith initial excess enthalpy temperature θ ₀ratio;

$\frac{{\mathrm{\&theta;}}_w}{{\mathrm{\&theta;}}_0}=\frac{t_{\max }-t_{\&infin;}}{t_0-t_{\&infin;}}$

Wherein, t _maxthe maximum temperature that while qualification for instrument, its electronic unit bears, t _∞environment maximum temperature, t ₀for instrument initial temperature;

D) utilize following formula to determine center excess enthalpy temperature θ _mwith initial excess enthalpy temperature θ ₀ratio;

$\frac{{\mathrm{\&theta;}}_m}{{\mathrm{\&theta;}}_0}=\frac{{\mathrm{\&theta;}}_w}{{\mathrm{\&theta;}}_0}/\frac{{\mathrm{\&theta;}}_{\mathrm{\&theta;}}}{{\mathrm{\&theta;}}_m}$

E) the complete wet several Bi by meter body with

in nomograph, check in

utilize following formula to draw heat stagnation time τ;

$\mathrm{\&tau;}=f(\mathrm{Bi},\frac{{\mathrm{\&theta;}}_m}{{\mathrm{\&theta;}}_0})\frac{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA00002544942200011.png"\; state="\{\{state\}\}">R</figure-callout>}}^2}{\mathrm{\&alpha;}}$

Wherein, a is thermal diffusivity, and heat stagnation time τ is now that the electrical component temperature at instrument radius r place rises to t _maxthe required time.

2) after drawing the heat stagnation time, then determine the transient temperature time t that raises, the moment that transient temperature raises rises, and recovers the normal moment to transient temperature, time apart between these two moment;

Under major accident condition, in containment, may produce the situation that transient temperature raises, Fig. 2 is the interior temperature variation of containment under a kind of typical major accident condition, can determine the duration of transient temperature by this figure, time period between the starting point that transient temperature is raise and transient temperature recovery are normal is defined as t, under different emergency conditions, can draw corresponding t according to temperature variation in its containment.

3) by the transient temperature duration in instrument heat stagnation time and containment on recently judging the quick-fried impact on instrument of hydrogen;

Determine according to step 1) the maximum (t that gauge internal circuit board rising instrument can bear _max) the heat stagnation time, step 2) determined the duration t that in containment, transient temperature raises.Apparent thus, if τ is more than or equal to t, illustrate under major accident condition when appliance circuit plate institute bearing temperature not yet reaches instrument and identifies the maximum temperature of bearing, in containment, temperature obviously declines, the temperature that therefore can specify this transient state raises instrument is not affected, the function that can not affect instrument, instrument still can be used under this emergency conditions.If τ is less than t, the temperature of the transient state under this environmental baseline raises and may impact instrument, and instrument exists disabled risk.

Obviously, those skilled in the art can carry out various changes and modification and not depart from the spirit and scope of the present invention the present invention.If these amendments and within modification belongs to the scope of the claims in the present invention and equivalent technologies thereof, the present invention is also intended to comprise these changes and modification interior.

Claims (1)

1. the determination methods of transient high temperature on instrument impact, is characterized in that, the method comprises the steps:

1) determine instrument heat stagnation time τ, heat is delivered to the time of internal electrical components from gauge external, and its method is as follows:

A) utilize following formula to determine complete wet several Bi of meter body

$\mathrm{Bi}=\frac{h}{\mathrm{\&lambda;R}}$

Wherein: h is convection transfer rate, λ is meter case coefficient of heat conductivity, and R is the cylindrical radius of meter case;

B) the complete wet several Bi by meter body with

in nomograph, draw

functional value, utilizes following formula to draw final excess enthalpy temperature θ _wwith center excess enthalpy temperature θ _mratio;

$\frac{{\mathrm{\&theta;}}_w}{{\mathrm{\&theta;}}_m}=f(\mathrm{Bi},\frac{r}{R})$

Wherein, r is the distance of electronic unit apart from outside surface, θ _wfor final excess enthalpy temperature, θ _mcentered by excess enthalpy temperature;

C) utilize following formula to obtain the final excess enthalpy temperature θ of instrument _wwith initial excess enthalpy temperature θ ₀ratio;

$\frac{{\mathrm{\&theta;}}_w}{{\mathrm{\&theta;}}_0}=\frac{t_{\max }-t_{\&infin;}}{t_0-t_{\&infin;}}$

Wherein, t _maxthe maximum temperature that while qualification for instrument, its electronic unit bears, t _∞environment maximum temperature, t ₀for instrument initial temperature;

D) utilize following formula to determine center excess enthalpy temperature θ _mwith initial excess enthalpy temperature θ ₀ratio;

$\frac{{\mathrm{\&theta;}}_m}{{\mathrm{\&theta;}}_0}=\frac{{\mathrm{\&theta;}}_w}{{\mathrm{\&theta;}}_0}/\frac{{\mathrm{\&theta;}}_{\mathrm{\&theta;}}}{{\mathrm{\&theta;}}_m}$

E) the complete wet several Bi by meter body with in nomograph, check in

utilize following formula to draw heat stagnation time τ;

$\mathrm{\&tau;}=f(\mathrm{Bi},\frac{{\mathrm{\&theta;}}_m}{{\mathrm{\&theta;}}_0})\frac{R^2}{\mathrm{\&alpha;}}$

Wherein, a is thermal diffusivity;

2) determine the transient temperature time t that raises, the moment that transient temperature raises rises, and recovers the normal moment to transient temperature, time apart between these two moment;

3) by the transient temperature duration in instrument heat stagnation time and containment on recently judging the quick-fried impact on instrument of hydrogen;

If τ is more than or equal to t, the temperature of transient state raises does not affect instrument, can not affect the function of instrument;

If τ is less than t, the temperature of transient state raises and may impact instrument, and instrument exists disabled risk.

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