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The uranium content of some international standards
EARTH AND PLANETARY SCIENCE LETTERS 1 (1966) 317-318. NORTH-HOLLAND PUBL. COMP., AMSTERDAM
THE URANIUM
CONTENT
OF SOME I N T E R N A T I O N A L
STANDARDS
E. I. HAMILTON Radiological Protection Service, Sutton, Surrey, England Received 29 June 1966
The u r a n i u m content of six United States Geol o g i c a l Survey s t a n d a r d rocks, t h r e e U.S. D e p a r t m e n t of C o m m e r c e , B u r e a u of Standards s a m p l e s and two I n t e r n a t i o n a l Atomic E n e r g y Agency, Vienna, b i o l o g i c a l s t a n d a r d s have been d e t e r m i n e d by the delayed neutron method [1-3]. The co n s t an cy of the isotopic c o m p o s i t i o n of u r a nium is well e s t a b l i s h e d for n a t u r a l s a m p l e s of u r a n i u m although m o s t p r o c e s s e d u r a n i u m r e agents a r e now p r e p a r e d f r o m 235U depleted u r a nium. As the delayed n e u tr o n method is dependent upon the c o n c e n t r a t i o n of 235U a s e r i e s of uranium standards were prepared from natural o r e s . The s p e c i f i c activity for n a t u r a l u r a n i u m and 235U depleted u r a n i u m is given in table 1; the r e a g e n t u r a n i u m s a m p l e no. 4 has been used in the p a s t as a standard, but f r o m t h e s e analy s e s it is a p p a r e n t l y depleted in 235U. F r o m r e agent s a m p l e s a v a i l a b l e to the author depleted u r a n i u m has been m a r k e t e d at l e a s t s in c e 1957, although it has probably been a v a i l a b l e s i n c e 1948. I n t e r f e r e n c e f r o m delayed n e u t r o n s f r o m thor i u m has been adequately allowed for in the USGS s a m p l e s by e s t i m a t i n g the t h o r i u m content by the thoronol method a f t e r p r e l i m i n a r y c h e m i cal e x t r a c t i o n of t h o r i u m . T h o r i u m can be d e t e r mined by e l i m i n a t i n g slow neutron f i s s i o n through
shielding the s a m p l e with a c a d m i u m foil; at p r e s e n t a suitable lined rabbit c o n t a i n e r is not available. The delayed neutron e m i s s i o n , with the c u r r e n t B F 3 counter, for u r a n i u m is 433 + 16 c p m / ~ t g U c o m p a r e d to 1 + 0.2 ~: c p m / p g Th. The u r a n i u m content of the p e r i d o t i t e , dunite and milk s a m p l e s is n e a r the l i m i t s of d et ect i o n with the c u r r e n t neutron co u n t er u si n g a m a x i m u m s a m p l e weight allowed by the rabbit s y s tem. The n u m b e r of m e a s u r e m e n t s r e p o r t e d in this p a p e r have been r e s t r i c t e d as only a l i m i t e d amount of s a m p l e was available, the r e m a i n d e r being c o n s e r v e d for X - r a y f l u o r e s c e n c e and spark source mass spectrometry determinations of o t h er e l e m e n t s . References [1] S. Amiel, Analytical application of delayed neutron emission in fissionable material, Report IA-621 Israel AEC (1961) 58 p. [2] F. F. Dyer, J . F . E m e r y and G.W. Leddicotte, A comprehensive study of the neutron activation anal),sis of uranium by delayedneutron counting, ORNL3342. UC-4-Chem., TID-4500 (17th ed. rev.) (1962) p. 71. [3] E.I. Hamilton, The determination of uranium in • rocks and minerals by the delayed neutron method, Earth Planet. Sci. Letters 1 (1966) 77.
Table 1 The delayed neutron count rate for various samples of uranium. Sample no. Natural uranium 1 2 3 235Uranium depleted 4 5
Concentration of original standard solution
Range of uranium aliquots (~.g U/ml)
cpm//~gU
Number of analysis
Uraninite* S. Africa Pitchblende S.W. England i Monazite S.tandard
175.6 gg U/ml 108.4 ~g U/ml 6.02% ThO 2 0.12% U30 s
172.63- 3.39 5.85- 1.39 343.80-44.76
430 :e 32 435 ± 12 436 ± 20
12 15 5
Uranium Standard Uranium nitrate standard I (purchased 1957)
16.8 10.0
16.8 1.05- 9.98
381 ± 10 271 ± 10
2 4
Source of uranium
* Kindly supplied by A.E.R.E. Warren Springs Laboratory, England.
318
E. I. HAMILTON Table 2 The u r a n i u m content of s o m e s t a n d a r d s a m p l e s , ]
Sample
U r a n i u m (ppm)
E stimated thorium content (ppm)
U. S. G. S. Standards G r a n i t e G - 2 (Split 43, P o s i t i o n 31) G r a n o d i o r i t e GSP - 1 (Split 34, P o s i t i o n 26) Andesite AGV - 1 (Split III, P o s i t i o n 30) B a s a l t BCR - 1 (Split 20, P o s i t i o n 17) P e r i d o t i t e PCC - 1 (Split 39, P o s i t i o n 22) Dunite DTS - 1 (Split II, P o s i t i o n 10)
1.64 (1.63, 1.66) 1.80 (1.80, 1.80) 1.47 (1.51, 1.42)
1.42 (1.42, 1.42) 0.005 0.003
40 100 10 10 n.d. * n.d.
Department of Commerce, Bureau Stds. U.S. May (1962) No. 89 Lead - B a r i u m - G l a s s No. 91 Opal G l a s s No. 99 Soda F e l d s p a r
0.30 0.54 1.09
n.d.
0.002 0.25 (0.23, 0.25, 0.27)
n.d.
n.d. n.d.
International Atomic Agency, Vienna D r i e d milk A s h e d vegetation * n.d. - not d e t e r m i n e d .
n.d.
/
THE URANIUM
CONTENT
OF SOME I N T E R N A T I O N A L
STANDARDS
E. I. HAMILTON Radiological Protection Service, Sutton, Surrey, England Received 29 June 1966
The u r a n i u m content of six United States Geol o g i c a l Survey s t a n d a r d rocks, t h r e e U.S. D e p a r t m e n t of C o m m e r c e , B u r e a u of Standards s a m p l e s and two I n t e r n a t i o n a l Atomic E n e r g y Agency, Vienna, b i o l o g i c a l s t a n d a r d s have been d e t e r m i n e d by the delayed neutron method [1-3]. The co n s t an cy of the isotopic c o m p o s i t i o n of u r a nium is well e s t a b l i s h e d for n a t u r a l s a m p l e s of u r a n i u m although m o s t p r o c e s s e d u r a n i u m r e agents a r e now p r e p a r e d f r o m 235U depleted u r a nium. As the delayed n e u tr o n method is dependent upon the c o n c e n t r a t i o n of 235U a s e r i e s of uranium standards were prepared from natural o r e s . The s p e c i f i c activity for n a t u r a l u r a n i u m and 235U depleted u r a n i u m is given in table 1; the r e a g e n t u r a n i u m s a m p l e no. 4 has been used in the p a s t as a standard, but f r o m t h e s e analy s e s it is a p p a r e n t l y depleted in 235U. F r o m r e agent s a m p l e s a v a i l a b l e to the author depleted u r a n i u m has been m a r k e t e d at l e a s t s in c e 1957, although it has probably been a v a i l a b l e s i n c e 1948. I n t e r f e r e n c e f r o m delayed n e u t r o n s f r o m thor i u m has been adequately allowed for in the USGS s a m p l e s by e s t i m a t i n g the t h o r i u m content by the thoronol method a f t e r p r e l i m i n a r y c h e m i cal e x t r a c t i o n of t h o r i u m . T h o r i u m can be d e t e r mined by e l i m i n a t i n g slow neutron f i s s i o n through
shielding the s a m p l e with a c a d m i u m foil; at p r e s e n t a suitable lined rabbit c o n t a i n e r is not available. The delayed neutron e m i s s i o n , with the c u r r e n t B F 3 counter, for u r a n i u m is 433 + 16 c p m / ~ t g U c o m p a r e d to 1 + 0.2 ~: c p m / p g Th. The u r a n i u m content of the p e r i d o t i t e , dunite and milk s a m p l e s is n e a r the l i m i t s of d et ect i o n with the c u r r e n t neutron co u n t er u si n g a m a x i m u m s a m p l e weight allowed by the rabbit s y s tem. The n u m b e r of m e a s u r e m e n t s r e p o r t e d in this p a p e r have been r e s t r i c t e d as only a l i m i t e d amount of s a m p l e was available, the r e m a i n d e r being c o n s e r v e d for X - r a y f l u o r e s c e n c e and spark source mass spectrometry determinations of o t h er e l e m e n t s . References [1] S. Amiel, Analytical application of delayed neutron emission in fissionable material, Report IA-621 Israel AEC (1961) 58 p. [2] F. F. Dyer, J . F . E m e r y and G.W. Leddicotte, A comprehensive study of the neutron activation anal),sis of uranium by delayedneutron counting, ORNL3342. UC-4-Chem., TID-4500 (17th ed. rev.) (1962) p. 71. [3] E.I. Hamilton, The determination of uranium in • rocks and minerals by the delayed neutron method, Earth Planet. Sci. Letters 1 (1966) 77.
Table 1 The delayed neutron count rate for various samples of uranium. Sample no. Natural uranium 1 2 3 235Uranium depleted 4 5
Concentration of original standard solution
Range of uranium aliquots (~.g U/ml)
cpm//~gU
Number of analysis
Uraninite* S. Africa Pitchblende S.W. England i Monazite S.tandard
175.6 gg U/ml 108.4 ~g U/ml 6.02% ThO 2 0.12% U30 s
172.63- 3.39 5.85- 1.39 343.80-44.76
430 :e 32 435 ± 12 436 ± 20
12 15 5
Uranium Standard Uranium nitrate standard I (purchased 1957)
16.8 10.0
16.8 1.05- 9.98
381 ± 10 271 ± 10
2 4
Source of uranium
* Kindly supplied by A.E.R.E. Warren Springs Laboratory, England.
318
E. I. HAMILTON Table 2 The u r a n i u m content of s o m e s t a n d a r d s a m p l e s , ]
Sample
U r a n i u m (ppm)
E stimated thorium content (ppm)
U. S. G. S. Standards G r a n i t e G - 2 (Split 43, P o s i t i o n 31) G r a n o d i o r i t e GSP - 1 (Split 34, P o s i t i o n 26) Andesite AGV - 1 (Split III, P o s i t i o n 30) B a s a l t BCR - 1 (Split 20, P o s i t i o n 17) P e r i d o t i t e PCC - 1 (Split 39, P o s i t i o n 22) Dunite DTS - 1 (Split II, P o s i t i o n 10)
1.64 (1.63, 1.66) 1.80 (1.80, 1.80) 1.47 (1.51, 1.42)
1.42 (1.42, 1.42) 0.005 0.003
40 100 10 10 n.d. * n.d.
Department of Commerce, Bureau Stds. U.S. May (1962) No. 89 Lead - B a r i u m - G l a s s No. 91 Opal G l a s s No. 99 Soda F e l d s p a r
0.30 0.54 1.09
n.d.
0.002 0.25 (0.23, 0.25, 0.27)
n.d.
n.d. n.d.
International Atomic Agency, Vienna D r i e d milk A s h e d vegetation * n.d. - not d e t e r m i n e d .
n.d.
/