Uranium and radon estimation in some water samples from Himalayas

Nucl. Tracks Radiat. Meas., Vol. 15, Nos. 1-4, pp. 791-793, 1988 Int. J. Radiat. Appl. lnstrum., PartD 0191-278X/89$3.00 + .00 (~) 1989Pergamon Press plc Printed in Great Britain URANIUM A N D R A D O N E S T I M A T I O N IN SOME WATER SAMPLES F R O M H I M A L A Y A S R.C. RAMOLA, SURINDER SINGH and H.S. VIRK Department of Physics, Guru A~ritlsr-143005, Nanak Dev University, India. A b s t r a c t - The u r a n i u m c o n t e n t o f w a t e r samples c o l l e c t e d from Kumaun ( U t t a r P r a d e s h ) and S t w a l t k ( H t m a c h a l P r a d e s h ) Himalayas has been e s t i m a t e d u s i n g t h e t e c h n i q u e o f f i s s i o n track registration in lexan plastic. The u r a n i u m c o n t e n t has been found v a r y f r o m 1 . 0 8 + 0 . 0 2 t o 3 5 . 8 3 + 0 . 0 9 ppb. The radon e s t i m a t i o n has a l s o ~een made i n the-same w a t e r samples u s i n g LR-115, t y p e I I p l a s t i c t r a c k d e t e c t o r . The radon c o n t e n t has been f o u n d t o v a r y from 2 . 6 8 + 0 . 2 3 t o 12.55 + 0.93 p C t / 1 . No d i r e c t c o r r e l a t i o n has ~een found betwee~ uranium and radon c o n t e n t s . However, t h e h i g h values of uranium in the mineralized areas confirm that the fission track method • can successfully be employed for uranium exploration. 1. INTRODUCTION Uranium can be measured by v a r i o u s t e c h n i q u e s v t z . a c t i v a t i o n enalTats, mass s p e c t r o m e t r y , f l o u r e s c e n c e and d e l a y e d n e u t r o n c o u n t i n g . Since the d i s c o v e r y o f s o l i d s t a t e n u c l e a r t r a c k d e t e c t o r s , an a d d i t i o n a l method i s a v a i l a b l e t o d e t e r m i n e t h e u r a n i u m c ° n c e n t r a t t ° n l i D o r o c k s and m i n e r a l s o f both the terrestrial and extra-terrestlal origin " . The track etch t e c h n i q u e w h i c h i s f i n d i n g many t e c h n o l o g i c a l applications6,7, can be e a s i l y used t o f t n d u r a n i u m c o n t e n t i n w a t e r . The r a d o n d e t e c t i o n i n w a t e r indicates the high potential f o r d e t e c t i o n of s t r u c t u r a l f e a t u r e s as w e l l as u r a n i u m o c c u r r e n c e 8. Rag e t a l . 9 c a r r i e d o u t t h e r a d o n measurements i n the hot springs for investigation of geothermal energy sources. In present s t u d y , a s i m p l e a p p a r a t u s e m p l o y i n g LR-115, t y p e I I p l a s t i c as a l p h a t r a c k r e c o r d e r i s used t o d e t e c t t h e a l p h a a c t i v i t y o f w a t e r samples c o l l e c t e d f r o m Kumaun ( U t t a r P r a d e s h ) and S t w a l t k (Htmachal P r a d e s h ) Himalayas due t o radon. Uranium e s t i m a t i o n i s made i n w a t e r u s i n g f i s s i o n track technique to study its correlation with radon. 2. EXPERIMENTS The e x p e r i m e n t a l p r o c e d u r e f o r u r a n i u m e s t i m a t i o n reported elsewherelO-13. The u r a n i u m c o n c e n t r a t i o n using the formula: TM i n w a t e r i s same as in water is determined (I) Cw = VGNA E~ o w h e r e symboles have t h e i r u s u a l m e a n i n g s . The method p r o v i d e s a d e t e c t i o n limit o f 0 . 0 1 ppb and a p r e c i s i o n i s s t a t e d t o be + 1 0 - 1 5 ~ and +5 ~ ( R e f . 1 4 and 1 5 ) . The a p p a r a t u s used t o d e t e c t a l p h a a c t i v i t y due t o r a d o n i s same as reported elsewherel3. 200 ml of each sample i s t a k e n i n r a d o n t i g h t r e a g e n t b o t t l e o f one l t t r e capacity connected with a conical flask through a hand o p e r a t e d r u b b e r pump and t h e g l a s s b u l b c o n t a i n i n g CaCI2 t o a b s o r b moisture. LR-115, t y p e I I p l a s t i c t r a c k d e t e c t o r s each 1 cm2 i n area a r e suspended i n t h e c o n i c a l f l a s k f o r a p e r i o d o f 15 d a y s . The radon gas i s t r a n s f e r e d from t h e r e a g e n t b o t t l e t o t h e c o n i c a l f l a s k by b u b b l i n g w a t e r and s u c k i n g t h e gas w i t h t h e h e l p o f a hand o p e r a t e d r u b b e r pump. A l l t h e d e t e c t o r s a r e e t c h e d i n 2.5N NaOH s o l u t i o n a t 60oc f o r 2 h r s and a r e scanned u n d e r an o p t i c a l m i c r o s c o p e f o r t r a c k d e n s i t y m e a s u r e m e n t s . Track density is converted into radon activity i n p C t / 1 by u s t u g a c a l i b r a t i o n c o n s t a n t (1 p C i / 1 o f r a d o n c o r r e s p o n d s t o 16.8 t r a c k s / c m 2 f o r 15 days 791 792 R . C . R A M O L A et al. exposure p e r i o d ) determined by Stngh e t a l . 16 i n t h i s l a b o r a t o r y . Detect i o n l i m i t of radon d e t e r m i n a t i o n was found to be 0.5 p C i / 1 by t h i s t r a c k etch method, w i t h a p r e c i s i o n of 5 - 1 0 ~ . The d e t e c t i o n l i m i t can f u r t h e r be lowered by increasing the exposure p e r i o d . 3. RESULTS AND DISCUSSION The r e s u l t s f o r uranium and radon c o n t e n t i n water samples are given i n Table 1. The uranium c o n t e n t i n the w a t e r samples i s determined by using Table 1. Radon and Uranium c o n c e n t r a t i o n Sample location UTTAR PR~DESH Nanak Mats A1Dh~ T r a c k A n a l y s t s Track d e n s i t y Radon a c t i v i t y (tracks/cmi) (pCi/1) Kancht Mandir R a t i Ghat Kharana Panyali Kalarmal Guralt 83 146 45 143 211 45 50 158 144 45 HIMACHAL PRADESH Samur Kalan Rameda 166 181 Bhimtal Nainital Llnglot 4.94~0.36 8.69~0.48 2.68_+0.23 i n water samples F.T. A n a l y s i s T o t a l No. U c o n t e n t of t r a c k s (ppb) 5.46_+0.04 1.66~0.02 1.82+0.02 12.55~0.93 2,68+0.23 2.98+0.25 9.40~0.59 8.57_+0.55 2,68¢0.24 11616 3520 3872 2304 4928 5856 9312 6432 4992 20560 9.8820.89 10.77+0.86 38688 76164 18.20+_0.07 35,83_+0.09 8.51_+0.79 1.08+0,02 2.32_+0.02 2.75+0.03 4.38+0.03 3.03+0.03 2.35_+0.02 9,68+0.07 equation 1. The uranium values i n Samurkalan and Rameda areas of H.P. and G u r a l t area of U.P. are found c o m p a r a t i v e l y h i g h e r than i n other areas. Atomic Minerals D i v i s i o n , Department of Atomic Energy, I n d i a has a l r e a d y r e p o r t e d the presence of uranium i n Samur Kalan and Rameda areas. The presence of uranium i n w a t e r samples can be due to the f o l l o w i n g two possibilities: ( l ) U r a n t u m p r e s e n t i n suspended or c o l l o i d a l i m p u r i t i e s . (2) Uranium d e r i v e d by the l e a c h i n g of rocks through which the water traverses. The suspended i m p u r i t i e s , i f p r e s e n t i n large s i z e , are easy to f i l t e r , b u t when the s i z e i s v e r y s m a l l , they w i l l give r i s e to c l u s t e r of t r a c k s whereas they are deposited i n t h i n f i l m . The number of c l u s t e r s found i n our study was n e g l i g i b l e and i f any, the number of t r a c k s i n a c l u s t e r d i d not exceed 100. I t r u l e s out the c o n t r i b u t i o n of uranium due to suspended impurities. The radon values i n water samples are found to vary from 2.68_+0.23 to 12.55+0.93 p C i / 1 . The water samples from Kanchi Mandir, BhimtaI, L i n g l o t , PanyaTi and Kalarmal areas have y i e l d e d e x c e p t i o n a l l y high values of radon c o n t e n t i r r e s p e c t i v e of t h e i r low U c o n t e n t v a l u e s . The high values of radon i n these areas may be due t o radium separated from u r a n $ ~ and precipitating f o r a long time on the w a l l s of f r a c t u r e d rocks A . No d i r e c t c o r r e l a t i o n was found between radon a c t i v i t y and uranium c o n t e n t . However, both the radon and uranium values are found h i g h e r i n Samur Kalan and Rameda areas, which may be due t o the presence of uranium i n these areas. 4 . CONCLUSIONS The h i g h v a l u e s o f u r a n i u m i n m i n e r a l i z e d a r e a s c o n f i r m t h a t t h e f i s s i o n t r a c k method c o u l d be s u c c e s s f u l l y employed in the uranium exploration. Radon e s t i m a t i o n method c a n be u s e d a s an a d d i t i o n a l t e c h n i q u e . However, t h i s technique may g i v e some spurious anomalies due t o the presence of URANIUM AND R A D O N ESTIMATION 793 radium. The present s t u d y a l s o h i g h l i g h t s t h e anomalous uranium c o n t e n t o f 9.68¢0.07 ppb i n w a t e r samples c o l l e c t e d from G u r a l i a r e a , i n d i c a t i n g need f o r f u r t h e r i n v e s t i g a t i o n of U m i n e r a l i z a t i o n i n t h i s area, Acknowledgement - The a u t h o r s acknowledge the f i n a n c i a l C o u n c i l o f S c i e n t i f i c and I n d u s t r i a l Research, New D e l h i . assistance of REFERENCES 1. 2. 3. J.D. Kleeman and J . F . L o v e r t n g . S c i e n c e 156, 5 1 2 ( 1 9 6 7 ) . D.E. F i s h e r . Geochtm. Cosmochtm. Acta 34, 6 3 0 ( 1 9 7 0 ) . M.Ka Nag~al, K.K. Nagpal and P.P. Mehta. Pure and A p p l . Geophys. 102, 4. R . L , F l e t s c h e r , P.B. P r i c e and R.M. Walker. N u c l e a r Tracks i n S o l i d s , P r i n c i p l e s and A p p l i c a t i o n s , U n i v . o f C a l i f o r n i a Press t Berkelay(1975)o S. Stngh and H.S. V t r k . J. E a r t h and Space Phys. 15, 1(1986). R.M. Walker. S o l i d S t a t e Nuclear Track D e t e c t o r s ; Achievements and c u r r e n t Problems. SSP-34(1973). M.K. Nagpal, P.P. Mehta, K.K. N a g p a l and Rama. Pram?na 1, 112(1973). W.Dyck and B. Tan. J. Geochem. E x p l o r . I 0 , 1 5 3 ( 1 9 7 8 ) . V.V. Rao, P.C. Ghosh and N.S. B h a l l a . Geoview$ V I , 37(1979). R . L . F l e t s c h e r and D.Bo L o v e t t . Geochtm. Cosmochtm. Acta 32, 1126 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 153(1973). (1968). M.K. Nagpal, K.K. Nagpal and A.K. Bhan. C u r r . S c t . 43, 8 ( 1 9 7 4 ) . H.S. V t r k and H. Kaur. C u r r . S c t . 48, 2 9 3 ( 1 9 7 9 ) . N.P. Stngh, M. Singh , S. Stngh and H.S. V t r k . N u c l . Tracks and Rad. Meas. 8, 483(1984). F.N. Ward and W.F. Bondar. Geol. S u r v . Canada, Ecan. Geol. Report 31, 365(1979). G.Ro MahaJan, N.K. Chaudhury t R. Sampat-Kumar and RoH. I y e r . N u c l . I n s t r u m . Meth. 153, 2 5 3 ( 1 9 7 8 ) . M. Stngh, N.P. Stngh, S. Stngh and H.S. V t r k . N u c l . Tracks and Rad. Meas. 1 2 , 739(1986). V . L . S . Bhtmasankaram. Radiometrtc Methods o f E x p l o r a t i o n , Osmanta U n i v . Hyderabad, I n d i a ( 1 9 7 4 ) .