SU1363945A1 - Method of determining gas pressure in cylindrical hermetic shells - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to increase the sensitivity under the conditions of limiting the limiting temperature of the heating of the shell under the conditions of the holding pool for fuel rods of nuclear reactors. In the zone of the gas cavity 3, a thermal perturbation is applied to the surface of the casing 2 of the fuel element I using the heater 4. The heating temperature is recorded and stabilized by a block 9, the input of which is connected to the thermal receiver 8, and the output to the heater 4. At the same time, using the thermal receivers 5 and 6 connected to the plotter 7, the temperature of the shell is measured during the heating temperature in steady state measurement. A method for determining the gas pressure is also described, in which the power of the heater 4 is selected on the reference shell with the maximum gas pressure so that the stabilization temperature does not exceed the limiting heating temperature. 2 sec. f-ly, 4 ill. c & (L with Ci 00 from 4 :: cl

Description

I. chronology (ggiosigs to measure the technology, and IMRIIO to the methods for determining the Liv. Kmshhp;) in tnm.chh nuclear reactors.

The aim of the invention is to increase the sensitivity, in particular, under the conditions of limiting the maximum temperature of the shell and, for example, under the conditions of the pool (d) rocker for nuclear fuel reactors. FIG. t is a schematic diagram of the measurement of a davInIin gas; in fig. 2 shows a plot of temperature change at the site of heating; in fig. 3 - a characteristic view of the curves recorded by the differential thermal receiver; in fig. 4 - calibration curves.

FIG. 1 schematically shows a fuel rod 1 with a shell 2 and a gas cavity 3, a heater 4, two differentially switched on, 1P-LH jurmonrnemtspka 5, 6 connected to the core (}.) Onostroitel o 7, thermal receiver 8, sub. | heating and stabilization.

The method is carried out as follows.

TVel 1, dimensioned, en .g, the holding pool (not shown), is installed vertically, in the zone of the gas cavity 3, to the outer surface of the shell 2, fuel elements i with the nominal capacity; 1 4 butt-thermal disturbance, which is ocyniecr- tiarpeBa of the shell (for example, g of Eyumon and ohmic heaters, Copted with a shell and fed by the heating and stabilization unit 9) with subsequent stabilization — the heating temperature Tc below the boiling point of water (Fig. 2, D - temperature, t - -, - time). The registration of the heating temperature and its stabilization are carried out with the help of block 9. on | –re and stabilization, the input of which is connected to the thermal receiver 8, and the output to the heater 4. Simultaneously with the help of a differentially connected thermal receiver 5 and 6 (above) and below the heating point at the same distance from it and connected to the plotter 7, during the heating time, the temperature of the L shell (Fig. 3) is measured, from which the Aust temperature is measured in the measured 5A measuring mode dAycr / ch; 0. the measurements are carried out on reference samples Zugs with a zvezdnym dlaine.m.r for, determined Lugt for ra, part och1pmkh pressure P and plot 10 (. 4) dependences (P), then similar tests on the studied fuel element, Aycrt is determined for it, and the pressure in it is determined from the iO graph.

The way according to the second variant ocyniecT- c. goggle as follows. On the reference sample with a maximum p. the pressure range under study P, the pressure of the heating power in such a way that the minimum temperature and temperature in the hot water mode Tf is less than the temperature (, 1 boil water. By turning on the heater fia- heater 4, heat 1 inlet until the thermal receiver 8 reaches

temperature settings are set to T (Fig. 2). The heat source Wo changes and the measurements are repeated until the setting of T value does not correspond to the pre-selected stabilization temperature, which is the MCHbnje water boiling point, thus selecting the lower threshold of the heater MOP1NOSTI during subsequent tests. Then, the power of the heater is increased to the value of W, which is found in the range i V,

 l, 5Wo, and the tests of the reference samples described above were carried out, registering the gfemp Tc as the heater reached the stabilization temperature and the signal was differentially connected to the thermal receivers 5, 6. When the stabilization temperature was reached, the heating was stopped and the registered curves (Fig. 3). At the moments of stabilization of Tc, the AC values are determined, along which the calibration curve i1 is plotted (Fig. 4). Conduct similar

testing the tested fuel element 1, determining the AC and determining the pressure P by the curve I1; in the studied TV.

The limit value of the power l, chosen experimentally. At this power value of the heater times

stabilization of Tc standards almost became equal. The lower limit of power Wo was defined as the minimum power of the heater, n)) and which the temperature of the heater reached the set stabilization level. But, since in the studied fuel element the shell thickness may appear slightly larger (due to the allowable variation in fabrication) of the shell thickness of the standard with maximum pressure, then at equal pressures of the standard and the fuel element, the stabilization temperature may not be reached on the test sample, therefore heater power should be set higher than the value of Wo-. Offered. My method was experimentally tested on standards made of material from fuel rods of the type VVER and BN, in an aqueous medium at a stabilization temperature of 90 ° G. The samples were filled with helium and argon in the pressure range O-100 atm; The heater was made in the form of a low-inertia nichrome foil, and Chromel – Pell thermocouples were used as thermocouples. The heater fits snugly to the surface of the shell, covers half of the perimeter of the shell and has a length of 1.5 times the diameter of the shell. The thermally coupled thermal receivers were located at a distance of 5 mm from the edge of the heater, the thermocouple recording the heating temperature was located at the back of the heater in its center. In the quality of the group; 1n 7 used scribe H 306,. In a block of 9 SURF 4 with an adjustment and power unit. Comparative tests of the method according to the first version and the similar method were carried out, but in the mode of pulsed heating on VVER-type standards filled with helium to 50 and 100 atm. The pulse duration was 1.5 s, the maximum heating temperature per pulse was equal to the stabilization temperature, i.e. 90 ° C. The test result showed twice the sensitivity of the proposed method.

Claims (2)

1. A method for determining the pressure of a gas in cylindrical hermetic shells, at which a portion of a vertically installed shell is heated, measures its temperature at two equidistant points located above and below the heating point, characterized in that, in order to increase the sensitivity, carried out with a constant power heater up to standardization of TeMnrpaTypfj. by which the pressure of the gas is judged. 2. The method of determining the pressure gale and cylindrical sealed shells, at which a portion of a vertically installed shell is heated, measure its temperature at two equidistant points located above and below the heating section, comparing it with the temperature obtained in a similar way on a reference shell with a known gas pressure that differs from , in order to increase sensitivity in conditions of limiting the maximum temperature of the heater, on the reference shell with the maximum pressure in the studied pressure range Pp of the gas, they select the power Wo evatel so that the temperature stabilization That not exceed the maximum heating temperature of the heater power W is set in the range  1.5 Wo, record the time interval At reaching the stabilization temperature Tg, and the required pressure is judged by the maximum temperature of the shell heating during the time interval At. / 2 / T t V 1 FIG. g / 77 / 77gD AU. P, 0 c1 Vct Fig.Z t GP: . . t Pi R FIG L