Patent GB-786198-A (GB)
Title: Detection system for nuclear explosions
IPC: G21J5/00
Filed: 1954-08-10
Abstract: 786,198. Detecting nuclear explosions. SOC. NOUVELLE DE L'OUTILLAGE R.B.V. ET DE LA RADIO-INDUSTRIE. Aug. 10, 1954 [Sept. 2, 1953], No. 23233/54. Class 40 (3). [Also in Group XXXVIII] Apparatus for detecting nuclear explosions comprises an explosion proof shelter outside which are a light-sensitive device responding to the flash, and a pressure-sensitive device responsive to the shock wave, both connected to instruments within the shelter for calculating the range, position and power of the explosion. The total space in which an explosion may occur is supervised by a number of photo-cells each of which views one or more particular solid angles. A display board inside the shelter indicates the direction and elevation in which the explosion has occurred. In the arrangement of Fig. 3, photo-cells are situated behind lenses 16, 16a and screens 17, 17a the slope of which is delineated by opaque screens so that only explosions in one of the two solid angles covered will produce an output from the cell. Fig. 4 shows an arrangement in which ring- shaped screens 18 enable cell 15 to receive a flash from a particular elevation only. In the arrangement described with reference to Figs. 5, 6 and 7 (not shown), the ring is divided into fourteen bearing sections and eight elevation bands. The bands are defined by the cosine range of the angles they cover, the cosine difference, being the same for all bands. Three cells each observe four elevation bands and four cells five or more of the bearing sectors. The bands and sectors covered by the various cells overlap but the combination of the outputs indicate the direction of the explosion. The initial flash of the explosion is received by one of a number of photo-electric cells such as 19, 20 or a combination as described with reference to Figs. 4 and 5. Assuming the flash to have been received by cell 19 it energizes relay 21 which in turn energizes relay 24. Relay 24 locks and illuminates warning lamp 27a indicating the zone of the explosion and extinguishing lamp 27b. This relay also extends the low voltage supply from battery 26a to relay 28. Relay 28 connects batteries 26a, 26b to a charging supply through rectifiers 29a, 29b until a flash occurs when the batteries are isolated from the mains. Relay 28 also connects alarm bells 36 to the low voltage supply, supplies heating and H.T. potentials to oscillator 30 and amplifier 31 and energizes relays 32 allowing a timer 33 to start counting. Counting ceases when the shock wave shortcircuits by means of a pressure-sensitive switch such as a piezo-crystal or otherwise alters a resistor 38 forming part of a resistance bridge. The unbalanced voltage developed across a diagonal of the bridge operates relays 34 and 44. Relay 34 de-energizes relay 32 which releases its detent to latch the time wheel, the distance of movement of which is a measure of the distance of the explosion. A pressuresensitive device p such as a manometer forms part of a bridge circuit supplied by the output of oscillator 30. The unbalance of the bridge, dependent on the pressure is amplified at 31 and used to operate a peak detector 46. The power of the explosion may be determined from the shock wave transit time (determined by counter 33) and a peak voltage meter 46. Fig. 2 describes an arrangement for combining these two readings in which curves on the face of a disc rotated in accordance with the distance of the explosion are traversed by the pointer 46a. To determine the distance of a comparatively close nuclear explosion the total radio activity emitted to a detector during the propagation time of the explosion is measured. To this end ionization chamber 48, detecting gamma rays is connected to battery 26b by relay 28 so as to charge condenser 50 connected to peak voltmeter 51.