IMPLICATIONS OF THE U-232 DECAY CHAIN ACTIVITY FOR THE PROCESSING OF IRRADIATED THORIUM AND RECOVERED U-233
The problems introduced by the associated beta and gamma radiation from the U/sup 232/ decay chain in U/sup 233/ processing are of sufficient magnitude to introduce new considerations with respect to handling the U/sup 233/ product, processing and recycling the irradiated thorium, and setting decontamination specifications. The U/sup 232/ from an MTR slug had a U/sup 232/ content which would result in a gamma -ray dosage of about 600 r/hr at the surface of a 1 kg sphere of U/sup 233/ after secular equilibrium was reached in ten years. More than half as much radiation would be present at the end of two years. Remote handling of such U/sup 233/ would be required at even shorter periods after isolation. If this high U/sup 232/ content cannot be tolerated, much lower g/ ton levels must be used, since the fraction of the U/sup 232/ in U/sup 233/ is roughly proportional to the g/ton level. The bulk of the beta - and gamma emitting daughters of U/sup 232/ which are associated with the separated Th grows in during the cooling period prior to processing. A 4-in.-diameter billet of thorium 10 in. in length recovered from the MTR irradiated slug which had been cooled 200 days would have a gamma -ray dosage of 1.1 r/hour at the surface of the cylinder. This radiation would decay with the 1.9 year half life of Th/sup 228/. However, if the thorium were infinitely recycled with 270 days irradiation at the (MTR flux, 200 days cooling and 100 days allowed for slug refabrication, the dose rate at the surface of the billet would reach a limiting value of 2.1 r/ hour. This would require remote handling facilities for slug refabrication procedures. The beta and gamma activities of the U/sup 232/ decay chain must be taken into account in setting decontamination specifications for Th. (auth)
- Research Organization:
- Knolls Atomic Power Lab., Schenectady, N.Y.
- DOE Contract Number:
- W-31-109-ENG-52
- NSA Number:
- NSA-12-000745
- OSTI ID:
- 4330579
- Report Number(s):
- KAPL-1271
- Resource Relation:
- Other Information: Decl. Apr. 3, 1957. Orig. Receipt Date: 31-DEC-58
- Country of Publication:
- United States
- Language:
- English
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