Pyrotechnic devices of different types such as cable cutters, pyro valve, shock wave transmitters, bolt cutters, cartridges etc. are used in launch vehicles as well as in satellites. As these components are critical in nature and perform only once in their mission related functions, they are subjected to stringent quality control programme including NDE. Thermal neutron radiography is a suitable NDE method for inspection of pyro devices as they contain hydrogenous explosive material. An accelerator based neutron source was developed by attaching a beryllium and uranium target using polyethylene moderator to a 15 MeV radiographic linear accelerator. This target produces thermal neutron flux of 1.1 x 106 n/cm2/sec with L/D ratio of 16. Transfer imaging method using dysprosium converter screens was optimised for different types of pyro devices. Some of the parameters studied and optimised include dysprosium screen thickness, exposure and transfer times, image sharpness and L/D ratio. Image sharpness is an important factor in NR to resolve fine interface details in the pyro-devices. Resolution of 0.025 mm aluminium spacer was obtained as measured by ASTM sensitivity indicator.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.Vol. 3, pages 1461 - 1464 Publisher:Ashgate Publishing Company
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