Survey of available technology for auditing $sup 235$U enrichment in cascade equipment
A search for possible nondestructive techniques which might be utilized by a safeguards inspection team for auditing /sup 235/U enrichment of UF/sub 6/ in gaseous diffusion cascade equipment without access to the UF/sub 6/ itself was carried out at the ORGDP. The work included a literature survey of safeguards techniques in use by others, and a search for other methods or equipment which might be applied to the present objective. Various possible methods are evaluated briefly. Probable limited access to cascade equipment precludes the use of methods involving bulky equipment, including neutron and gamma generators, coincident or anticoincident counters and high energy isotopic neutron sources of sufficient strength to produce a measurable fission rate in /sup 238/U which requires large shields. Irradiation with low energy neutrons followed by detection of fission events and passive gamma measurements could provide information on the /sup 235/U content, but not on the 2/sup 238/U. Two methods upon which preliminary investigations were carried out are considered to warrant further development. The first involves a direct measurement of the /sup 235/U gamma radiation from UF/sub 6/ within a pipe and a measurement of the absorption of gamma rays from an external gamma source when these rays pass through the pipe walls and UF/sub 6/. The /sup 235/U gamma measurement indicates the amount of this isotope present, and the gamma absorption measurement, when corrected for pipe-wall absorption, indicates the total uranium present. Experimental tests indicated this method to be well within the scope of current technology. The tests included an evaluation of a commercially available ultrasonic gauge which could be used for pipe-wall thickness measurements. The second method involves the irradiation of the UF/sub 6/ with a moderated neutron source and the detection of gamma rays resulting from neutron capture in /sup 238/U and fissions induced in /sup 235/U. This method is considered to warrant further investigation, but its actual feasibility has not been established. (auth)
- Research Organization:
- Oak Ridge Gaseous Diffusion Plant, Tenn. (USA)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-26
- NSA Number:
- NSA-29-005589
- OSTI ID:
- 4404271
- Report Number(s):
- K--1844
- Country of Publication:
- United States
- Language:
- English
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