Registration system of leaks of a heat carrier for the first loop of the reactor facilities of the nuclear electric power plants
FIELD: atomic power engineering; registration systems of leaks of the heating carrier of the 1-st loops of the reactor facilities of nuclear electric power plants.
SUBSTANCE: the invention is pertaining to the field of atomic power engineering and may be used in at the reactor installations with the water-to-water and water-graphite reactors, in particular, at a decompression of the 1-st loop. The registration system of leaks of the heating carrier of the 1-st loops of the reactor facilities of a nuclear electric power plant contains a block of the controlled rooms with equipment of the 1-st loop of the reactor installation connected through air ducts of exhaust ventilation with a block of the channels intended for measuring of relative humidity of the air in the controlled rooms, that includes a reference channel intended for measuring of relative humidity of outdoor air in the rooms with the measuring channels. Sensor units of measuring channels are connected to a control unit for recording and matching of the parameters of the relative humidity of the air in the controlled rooms and in the room with the measuring channels, each of which is made in the form of an expander, on one butt of which there is a branch pipe with a filtering tool connected with the air duct, and on the other butt there is a flange intended for mounting of a sensor. At that outside of the expander there is a cooling chamber. The invention allows to simplify the process of the control over the indications of the relative humidity of the air in the controlled rooms and to improve reliability of operation of the reactor installation by well-timed detection of a location and intensity of the leakage of the heating carrier.
EFFECT: the invention ensure simplified control over the indications of the relative humidity of the air in the controlled rooms, improved reliability of the reactor installation operation by well-timed detection of a location and intensity of the heating carrier leakage.
6 cl, 9 dwg
This invention can be used on all reactor units (RU) of nuclear power plants (NPP) with water water and fotografirovali reactors.
At present in CIS on all speakers with the water water and fotografirovali RU does not provide the required normative-technical documentation, tools and detection methods with reasonable accuracy the location and flow rate of the leak of primary coolant".
Known for rapid detection and determine where leaks of coolant VVER (SCTT) website in Internethttp://diaprom.ru/work.htm, 2003.02.10. For measuring humidity in SCTT used "touch hose", which is placed inside the insulation in direct contact with the pipe or the surface of the reactor to ensure the diffusion of moisture into the touch of the tube.
Despite the fact that the basis of both systems is one and the same principle - the increase in the relative humidity when the coolant leak, different methods of obtaining data, and design of the systems themselves.
The main difference between the two systems is that for measuring humidity in SCTT used "touch hose", which is placed inside the insulation in direct contact with the pipe or the surface of the reactor, for the same purposes in CPT who use the system, "triggering unit controlled premises equipment of the primary circuit of the reactor, connected through the ducts and exhaust ventilation with a block of channels, designed to measure the relative humidity in the controlled space." As an example of Boxing, which is a few pieces of equipment and dozens of meters of piping. When working SKT computer center the signal on the occurrence of the leak may come from "touch hose" of any of the sections of the pipeline, flange connectors of the equipment, the surfaces of equipment, the number of such sites is large enough. When the work of the CPT signal leakage will be only one, the leak appeared in the box. Thus the sensitivity SCT will be possible and above, but at the same time and repeatedly will increase the cost of implementation, operation and repair of the system.
In addition, when working Committee establishes the flow of coolant leak, this option is not available when operating SCTT, CPT also provides the tools for testing, commissioning, and operational checks of measurement channels that SCTT impossible because of its design features.
The technical result of the invention consists in simplifying the process of monitoring the indications relative to the air humidity in the controlled space, and to simplify the installation (system), as well as to improve the reliability of the AC by timely detecting the location and flow rate of coolant leak if possible depressurization of the 1st circuit ROUX.
The proposed system (CPT) will allow with sufficient accuracy and speed to determine the appearance, flow, location (room) of the leak 1st circuit for AC with water water and fotografirovali reactor. The basis of the proposed system is the relative humidity of the air in the room when the leak.
The registration system leaks coolant 1 loop reactor of a nuclear power station includes a unit controlled premises equipment 1 loop reactor, connected through the ducts and exhaust ventilation with a block of channels, designed to measure the relative humidity in the controlled space, comprising a reference channel that is designed to measure the relative humidity of outside air to the measuring channels, with sensors measuring channels are connected with a control unit for registration and comparison of relative humidity in the controlled space and the location of the measurement channels.
For fotografirowac reactor system the mA further includes a unit casing fotografirovala reactor, associated bypass line forced ventilation unit of the measuring channel, designed for monitoring the integrity of the equipment within the specified casing, and the sensor of the measuring channel is connected to the control unit via an electrical connection.
Sensors measuring channels controlled premises connected with the computer means alarm triggered when the corresponding difference of the readings of any of the measurement channels with the reference.
Each measuring channel is made in the form of extender, one end of which a nozzle with filter means connected to the air pipe, and on the other end has a flange designed for mounting sensor, while outside extender placed a cooling chamber.
Measuring channel for fotografiloval reactor, designed to control the integrity of the equipment within the enclosure of the reactor, in the form of extender, one end of which is connected to the pipeline bypass line forced ventilation, fitted on the entrance to the extender throttle, and on the other end has a flange designed for mounting the sensor.
Duct exhaust ventilation equipped with an adjustable device for limiting air flow from the monitored houses is, is airtight.
The system includes means for testing, commissioning, and operational checks of measuring channels.
Measuring channels controlled premises is made with the possibility of connecting to the means for regulating and measuring the vacuum in the exhaust ventilation air duct.
The equipment and pipelines of the 1st contour RU AU are a few tight areas (boxes). Each room is equipped with exhaust ventilation. During operation of the proposed system the flow of air from the room must be restricted. The greater the consumption, the lower the sensitivity of the CPT, but the higher the speed the registration of the leak. The optimal ventilation rate (the ratio of the flow rate of the fan (m3per hour) to the volume of the room (m3from 1 to 0.5, and the rate of registration of the leak will be from 1 to 2 hours, respectively, but due to the low consumption, will increase the sensitivity of the system.
The basic rules ensure the operation of nuclear power plants RD EA 0348-02 not regulate the ratio of ventilation to the premises of the 1st loop, and only require "maintenance in these areas rarefaction within the project value, but not less than 5 kgf/m2in relation to other more "pure" relative to the radioactive contamination of the premises (p.). Therefore, to ensure the work of the CPT ducts is to limit the flow of air shall be equipped with control devices (gate valves), and the premises must be sufficiently tight.
According to the present invention, the number of measurement channels must be one greater than the number of controlled areas, and the installation of the sensors should be placed in a well ventilated area when lack of moisture. Additional channel (reference) is designed for monitoring the air from this space.
For speakers with fotografirovali RU measuring channel to control the density of the equipment inside the sealed casing of the reactor must be connected to the bypass line forced ventilation.
The basis of CPT laid eight-channel device IVTM-7/8P-MK JSC "Practic-NC". Eight channels of temperature and relative humidity will allow connection to the device sensors multiple reactor units AU. Secondary device type IVTM-7/8P-MK is installed on the control Board and provides control of temperature and relative humidity in all areas of the 1st circuit. All channels, except the reference with alarm on exceeding a relative humidity of 5% from the original.
The registration system leaks coolant 1 loop reactor installations of nuclear power plants includes registration of changes in the relative humidity of the air in the room of the 1st circuit is eattorney installation where appeared to flow.
Air flow through the room the 1st circuit limited to a relatively low limit, and to increase the sensitivity of the device selected for analysis from the air duct, is subjected to pass through several stages of cooling before it enters the sensor device.
Also use the reference measurement channel to exclude the effects of changes in the relative humidity of the outdoor air in the identification of coolant leak the 1st circuit.
The invention is illustrated in the drawing, in which figure 1 schematically shows a schematic diagram CPT; figure 2 - device channel circuit of figure 1 (in section); figure 3 - flange connection of the sensor; figure 4 is a section along a - a in figure 3; figure 5 - nozzle testing (in section); figure 6 - the vessel of constant volume; 7 - channel schemes for CPT fotografirowac RU (cut); on Fig - I-d chart moist air figure 9 - block diagram of the system.
Figure 1 is a schematic diagram CPT consisting of 3 measuring channels. Channel 1 is the reference, the measuring sensor enters the air with a relative humidity (ϕ)equal to the relative humidity of outside air, with an amendment to change of temperature (T)°C.
Each measuring channel (Ref. 1-3) consists of a sensor device 4, which used the Xia primary Converter IVTM-7M, extender-fridge 5, 2-stage filter 6, the device DNMP-US marked pos.7, which can be connected to each channel, pipe 8 with the valve in the form of needle bellows 9 and 10 valves for the supply, diversion of measured air, cooling water for cooling selected by means of control air to the temperature (T) of the ambient air and orifice plates 11 to limit the flow of sampled air and easier adjustment of the flow.
The sensor device IVTM-7M (position 4 in figure 1) is designed to measure T ϕ air for each channel, is fixed in the hole 43 of the flange 12 (figure 2).
Expander-the fridge is made of a pipe 13 with a diameter and thickness 57×3,5 with cooling jacket 14 (pipe diameter and thickness 76×3) and is designed to reduce the velocity of the air, cooling it and install it sensor and filter.
2-stage filter cleans the air for the purpose of protecting the outer surface of the sensor is performed with a high degree of purity from damage and contamination by aerosols.
The filter is made out of the socket 15 in diameter and thickness 57×3.5-inch, a length of 200 mm and the flange 16 with a nominal diameter (DN)=50 mm, nominal pressure (PN) 10 kgf/cm2. The pipe filled with tightly rolled cloth "Petryanov 17 and the flange connection of the inserted rubber gasket 18 with pasted is th at it from 2 sides fabric 19 of the respirator type "Lepestok-200".
Device type DNMP-US (pos.7 figure 1) is used as a meter of vacuum (air ducts of ventilation systems of the premises of the 1st circuit operate under vacuum) and can be connected to any channel. Is used to: - configure channels (restriction of air flow through the channel to 0.05-0.1 m3per hour); - control of the pressure drop across the filters during operation.
Piping with valves made of stainless steel with a diameter and a thickness of 14×2 mm and 6×1.5 mm and are designed for supply, exhaust bleed air, cooling water, cooling to room temperature, system configuration, enable or disable channels, including emergency, to save the sensor devices with the appearance of a leak in the premises. The sensors do not allow moisture condensation on the surface.
Washer throttle 11 (figure 1) with a hole diameter of 0.7 mm and a hole 20 (figure 2) in the expander 5, with a diameter of 1 mm, the measured air facilitate the adjustment of the air through the extender.
For setting up and operating tests CPT is applied is depicted in figure 5, the nozzle comprising a funnel 21, the pipe 22 with a diameter and a thickness of 6×1.5 mm, the pipe 23 with a diameter and a thickness of 14×2 mm, fitting with DN 10 mm (24) for connecting the air hose. The nozzle can be embedded in a ventilation duct or stored in the premises of the 1st circuit. Through in Ronco depicted in Fig.6 vessel 25 constant flow rate (CBR) through a pipe 22 enters the water with the established flow rate of 2-10 kg/hour. In annular space between pipe 22 and the pipe 23 through the wall of the room or the wall of the duct 42, receives compressed air with a pressure of 6-8 kg/cm2.
For the best spray a stream of water should be towards the air flow in the duct (figure 5).
When testing the flow rate of supplied water should be constant. This applies to a vessel 25 constant flow (AB); consisting of 2 inserted one into each of the vessels with a capacity of 1.5-2.0 liters. The outer vessel 26 is connected with the atmosphere, and on his neck a removable cover 27 with a hole on the consumption of 2-10 l/h. Covers should be several, at different costs. Through the removable cover of the outer vessel, the inner vessel 28 is filled with demineralized water, after which the cover is twisted and AB flips into position, is mounted on the funnel 21 (figure 5). At the end of the water from the outer vessel level therein falls below the neck of the inner vessel, the inner vessel is air, thus maintaining a constant level in the outer vessel, and hence a constant flow to the injector.
The high sensitivity of CPT (100-400 g/hour) is allowed to use instead of SRC surgical dropper. During routine inspections CPT instead of using the nozzles in the premises of the 1st circuit and the ducts can serve niskapate the social pairs in the pipelines with a nominal diameter (DN) of 10 mm, for example, from the head of the deaerator. At atmospheric deaerator through the throttle washer with a hole diameter of 4 mm and a flow rate of 8 kg/h, in the deaerator pressure of 6 kgf/cm2through the throttle washer with a hole diameter of 2 mm and a flow rate of 6 kg/hour.
For fotografirowac RU extra channel (7) for monitoring the integrity of the equipment in a sealed reactor vessel. It works similarly to other channels and differs from them in that useless it has no filter and the cooling jacket. At the entrance to the extender 29, conduit 30 is embedded fitting 31 with tube 32 for the test channel. The gas enters the channel from the pressure line forced ventilation through the pipeline 30 in which is installed a throttle washer 33, and enters into the suction line ventilation through the pipeline 34.
Figure 9 presents the block diagram of the proposed system, consisting of a block 35, for example, two controlled areas 36 and 37, which are placed in the equipment of the 1st loop of the reactor; block 38, which represents a well-ventilated room without moisture source that has two or more measuring channels: 1 - standard, 2 and 3 - United through the ducts respectively controlled areas 36 and 37. Sensors measuring channels 1-3 are connected to the electrical connection of the control unit 39, on the dash Board (the Board) which shows evidence of relative humidity and temperature controlled rooms 36 and 37 and the readings of relative humidity and temperature of the block 38, which registers the sensor is installed in this location reference measurement channel 1. On the specified shield can be mounted audio and/or visual elements of the alarm corresponding to the alarm on exceeding the allowable difference in the readings of any of the channels with the reference, which comes from is connected to the measuring channels of the computer device (IVTM-7/8P-MK).
For fotografirowac reactor is an additional block 40 with the measuring channel, a sensor which monitors the integrity of the equipment inside the block 41 where the reactor vessel. The blocks 40 and 41 are connected in the bypass line, and the block 40 to the control unit 39 electrical connection.
Technical finding of the proposed system is the use of such a volatile climate component, such as relative humidity (ϕ) for solving complex problems in a timely and accurate detection of coolant leak 1st circuit SA and its consumption. To solve this problem applies several methods:
1. The method of comparative analysis. As part of the scheme number will measure the selected channel is one greater than the number of controlled premises. The air for additional (reference) channel comes from a well-ventilated room, in which there are no sources of moisture, so ϕ this channel will be equal to ϕ outdoor air adjusted to a temperature increase (T)°C. All dilators are in one place and powered from a single source of cooling water, so that in the absence of coolant leak indications T, ϕ all channels, including the reference will be the same. Alarm setpoint overshoot ϕ exhibited at +5% from the original. Value ϕ varies significantly during the year, therefore, and alarm setpoint is changed in a year at least 5-6 times.
With the growth of ϕ 5% on any of the channels (except the reference), the alarm is activated, the operator compares the readings ϕ actuated channel with ϕ the reference channel. Synchronous growth ϕ indicates growth ϕ outdoor air, asynchronous - on of coolant leak.
1.1. The flow of coolant leak is determined by the formula:
where d2- moisture content (g/kg), the appropriate indications ϕ, T of the triggered channel will be determined by I-d diagram of moist air (Fig);
d1the moisture content corresponding to the indications ϕ, T of the reference channel;
σinthe flow rate of air (kg/the AU).
As in the set IVTM-7/8P-MK enters the computer, the program includes an algorithm alarm when the difference between the readings of any of the channels with the reference. This difference can be set at 2% and, therefore, the operational sensitivity of the CPT will be equal to 2%.
2. Seasonal differentiation of cooling extenders. The sensitivity of CPT in the first place depends on d outside air, the value of which during the year vary from 0.5 to 16 g/kg of the chart shows that the lower T of the measured air, the higher the sensitivity of the system, but to cool the air only to the T, where ϕ=70-80%in order to have a supply on the response of the system when the leak, so depending on the season of the year requires a certain cooling mode.
2.1. Mode I (1-I area of the chart) as the refrigerant used raw water with T=6±1°C.
The mode is used for 8 cold months of the year at the Bilibino speakers and 6 months on the Kola speakers.
2.2. Mode II (2 charts) - water cooling is not used, but the water in the cooling jacket of the extender stays and plays the role of thermo stabilizer, smoothing daily fluctuations in ambient temperature. Daily air consumption per channel is 1.5 kg, the amount of water in the expander - 0.7 kg, but it should be remembered that teploe is there air in 4 times lower than the heat capacity of water, therefore, the remaining water will be enough to smooth out daily fluctuations So Therefore the value of T at any time of the day will be very close to the average T ϕ depending on T during the day will not change.
Mode II1(2 charts) is used as a refrigerant technical water with T=13-18°C.
Mode II is used for 4 relatively warm months of the year at the Bilibino AC and 3 - Kola (except summer). Modes II and II1can be used for 6 cold months for speakers of European part of Russia.
2.3. Mode III (the 3rd area of the chart) - no water cooling. Similar to mode II water in the expander performs the role of thermo stabilizer. Mode III is different from the mode II higher T the measured air, and 3-I zone is located in the highest part of the chart. Used for 6 months for speakers of European part of Russia and for the 3 summer months for Kola speakers. It should be noted that the division of the modes except the Bilibino speakers, highly conditional and requires clarification after the trial operation of the CRT to the speakers.
2.4. Ideal operating Committee substitute seasonal differentiation of modes and suitable for any speaker could be the heater cooling water running in automatic mode. Tons of water support is alas such, to prevent growth ϕ above 70%. The scheme regulator should be such that when the ϕ=65, 70 and over 70% of the regulator demanded "greater than", and in all other cases "less than" full disconnection.
3. We define the sensitivity of CPT when working on different modes. Conditionally accepted airflow exhaust ventilation is operating on the premises of the 1st circuit is equal to 2000 kg/hour. In this case, when the volume of space 1000 m3the ventilation rate will be equal to 2, the reaction of the CPT (check the leakage after its occurrence) for 30 minutes, and the volume - 4000 m3the ventilation rate is 0.5, the reaction CPT - 2 hours.
The sensitivity of CPT defined by the formula:
where d2- change the moisture content corresponding to ϕ=2%;
σ - flow rate of air (kg/h).
Sensitivity σ=2000 kg/hour will be: I - f=280 g/h II mode - 480 g/h, III mode - 800 g/hour.
When determining air flow ventilation can be used by the Committee, submitting to the injector calibration of the water flow and to positivity consumption by the formula:
where Y is the calibrated water flow to the injector (3.6.10) kg/h;
Δd is the increment of moisture caused by this consumption (g/kg).
Because the instrument measures T and ϕthen calculate d on the chart is easy.4. Method of diagnosis in podcastalley zone. Is the density determination equipment by fold decrease (increase) consumption of the fan. Changing the flow of air produced by gate valves. For example: the volume of space - 500 m3. Consumption of fan - 2000 kg/h. For example, in the equipment leak with consumption in podcastalley zone, for example at 1-m mode - 140 g/hour. Reduce consumption 4 times up to 500 kg/hour. In the same time to increase the sensitivity of CPT and will be 280:4=70 g/hour. So, when reduced in 4 times the device will show the change in relative humidity of 4%. If at times the reduction in flow rate (2, 4, 6 times) the device remains at the initial condition, the equipment can be considered dense. This diagnosis should be performed before the release of ROUX in for repair, after repair, periodically during operation at least 1 time in 3 months.
5. The equipment and pipelines of the 1st circuit under high pressure and high T circulates saturated steam, superheated water and steam-water mixture. In violation of the density of equipment, even when the leakage a few pounds almost all hot water is turned into vapor and enters the room, where through the exhaust ventilation and purification system in the ventilation pipe. Pipeline CPT diameter and that is a woman 14× 2 mm, embedded in the duct to the control device, the air is supplied to the expander and passing through the sensor goes to the suction side of the fan. Passing through the pipe nominal diameter (DN) of 10 mm in length from 10 to 40 m with a speed equal to 0.2 m/sec, the air cools to T the environment and the expander (air speed - 0,008 m/s) T air is reduced to T the cooling water. Speed of 0.2 and 0.008 m/s is much lower air velocities in the convection heat transfer, so no advanced gas-dynamic and thermal calculations have not been carried out, moreover, that the specified speed is not limiting, and can be reduced by 2-3 times.
6. For fotografirowac reactors extra channel (7) for monitoring the integrity of the equipment in a sealed reactor vessel. This channel is fed to the bypass of forced ventilation gas circuit, operates without a filter and water cooling. Setpoint alarms on growth equal to ϕ+2%. Before entering the expander in the pipeline with a nominal diameter (DN) 10 mm welded fitting with tube (31, 32)serving for inspection. The check is performed as follows: the channel is turned off, the tube fitting is removed, and medical (eye) pipette in the pipeline drip 2-3 drops of water. Then the tube is put in place, the channel connected to the W and the response of the device is determined by the efficiency of the channel.
7. From points 2, 3 it can be seen that the Bilibino speaker has a distinct advantage over other speakers in the implementation of CPT. Advantage of this station is assumed to the unique climatic conditions of the location. The average T of the air in the area is 15°C. the Moisture content (d) within 8 months of below 2 g/kg, and in the remaining 4 months of rises only up to 8 g/kg Outwardly, it appears that the fog in winter (8 months of the year) appears only at 48-50°and in summer, despite the daily temperature difference T, up to 20°C, no dew nor haze. Within 8 months of tons of raw water is 6±1°that allows you to use it as an ideal refrigerant. Such ideal conditions for CPT allow to develop the project to implement it on other speakers.
1. The registration system leaks coolant 1 loop reactor installations of nuclear power plants, including unit controlled premises equipment 1 loop reactor, connected through the ducts and exhaust ventilation with a block of channels, designed to measure the relative humidity in the controlled space, comprising a reference channel that is designed to measure the relative humidity of outside air and with the measuring channels, while the sensors of the measuring channels are connected with a control unit for registration and comparison of relative humidity in the controlled space and the location of the measurement channels, each of which is made in the form of extender, one end of which a nozzle with filter means connected to the duct, and on the other end has a flange designed for mounting sensor, while outside extender placed a cooling chamber.
2. The system according to claim 1, which fotografiloval reactor additionally includes a block placed inside the reactor vessel and its associated bypass line forced ventilation of the measuring channel, designed to control the integrity of the equipment within the specified casing, and the sensor of the measuring channel is connected to the control unit via an electrical connection.
3. System according to any one of claims 1 and 2, in which the sensors of the measuring channels of the controlled premises connected with the computer means alarm triggered when the difference between the readings of any of the measurement channels with the reference.
4. The system according to claim 2, in which the measuring channel, designed to control the integrity of the equipment within the enclosure of the reactor, in the form of extender, one end of which the CSO is connected to the pipeline bypass line forced ventilation, provided at the entrance of the expander throttle, and on the other end has a flange designed for mounting the sensor.
5. The system according to claim 1, in which the duct exhaust ventilation equipped with an adjustable device for limiting the flow of air from the controlled space, is airtight.
6. System according to any one of claims 1 and 2, which includes means for testing, commissioning, and operational checks of measuring channels.
FIELD: nuclear engineering.
SUBSTANCE: the proposed invention is related to the ultrasonic methods of testing for detection of failed fuel elements and may be used when checking the lead-proofness of the fuel elements at spent fuel assemblies, being in water. The proposed methods includes excitation of ultrasonic waves in the fuel element can, detection of the useful reflected and twice reflected signals and determination of the nonleak-proofness when using the amplitude of the useful reflected signal. As a preliminary the ultrasonic waves are excited in the can of an air-tight fuel element or in its simulator by means at a transducer. In this case the wave frequency increases from 0.25 MHz. The value of the frequency of, at which the twice reflected signal is not detected, is determined. Then the ultrasonic waves at the frequency of are excited in the can of a tested fuel element and the conclusion is made on its nonleak-proofness.
EFFECT: increased sensitivity and reliability at detection of failed fuel elements.
3 cl, 10 dwg
FIELD: hygrometers with bolometric heat sensitive member, stove or furnace using such hygrometer and method for controlling stove or furnace.
SUBSTANCE: hygrometer includes two static bolometric heat sensitive members for accurate detection of humidity value. Stove or furnace includes bolometric hygrometer secured to one side of bracket in air discharge opening for deflecting direction of air flow in order to detect humidity value at high accuracy in cooking chamber. Method for controlling operation mode of stove or furnace provides different periods of heat treatment of food products in package or without it.
EFFECT: enhanced accuracy of humidity measuring.
13 cl, 15 dwg
FIELD: measurement technology.
SUBSTANCE: electric insulating base, electric insulating substrate onto which moisture-sensitive coating is applied on the base of gelatin which has its external layer tanned, two plated electrodes which have contact surface to contact with moisture-sensitive coating on base of gelatin and measuring device connected to outputs of plated electrodes. Two clamping units are introduced into the device additionally. Any clamping unit intends for creating permanent pressure of corresponding plated electrode onto working surface of moisture-sensitive coating on base of gelatin. Layer of gelatin coating has uniform thickness. Contact surface of plated electrodes adjacent the moisture-sensitive gelatin-based coating is made to be oxidized and flat.
EFFECT: prolonged service life; higher stability of operation; increased moisture resistance.
5 cl, 1 dwg