Responds to 940406 Ltr Requesting Addl Info Re Radioactive
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.,_ ., m 1 . .m m .. i - . MS-ilo- h'i g' BostonUniversity naaiation protection N W# Medical Center office ei Ncwton Street. D Mu limtor. Mawchosetts 02116 2 m 61' 63N'04 2 USNRC Region I I 475 Allendale Rd. King of Prussia, PA 19406 | Attn: Keith Brown, Ph.D. I June 24, 1994 ! Docket No. 030-01845 Control No. 118364 . Dear Dr. Brown, |I i We are responJ'ng to the April 6, 1994 request for additional informat W regarding radioactive incineration on our ' broad medical license # 20-02215-01. Questions 1 & 2 ) Per our May 5, 1994 telephone conversation, you indicated that we would be allowed to incinerate radioactive materials with half-lives less than 90 days for volume reduction. We therefere wish to be allowed to exercise this option as we previoucly ! stated in past letters, should we need to incinerate short-lived material with long-lived radwaste e.g. animal carcasses. ouestion 3 | l a) The following procedures will be performed to determine that ash generated from our incinerator is not radioactive. Ash Analysis of Gamma Emitters i Analysis of gamma emitters of ash is a procedure that is fairly straight forward and compares to our rcutinc r.nalysis for I gamma emitters with wipe tests and a radioic ination air sample ! measurements. These procedures have been described in our | license renewal. Ash would be sampled from the incinerator and i counted in a marinelli beaker using a high purity germanium detector coupled to a computer controlled Aptec software multichannel analysis system. While individual MDA's for different gamma emitters will vary, we estimate that we easily can measure activities in ash in nanocurie to picocurie ranges at the 95% confidence interval, our system is NIST calibrated and can identify unknown isotopes. This will easily verify that ash is not radioactive with gamma emitters in conformance with NRC regulations. 9601030207 951121 PDR FOIA BOVE95-183 PDR ||g3Q OFFICIAL RECORD COPY ML 10 ,. JR 24 m 966/()3o7p~/ h 2/ /, . - ( l - . Ash Analysis of Beta Emitters Ash analysis for beta emitters is a more difficult problem to measure especially for weak beta emitters as 3H and 14C. Direct counting of the ash with liquid scintillation counting will not work. We have attempted several techniques for extraction to measure the weak beta emitters and have decided on a modified EPA leaching procedure for sampling waste materials. We have determined that we can recover 93% of the radioactivity from 3H spiked incinerator ash and 80% for 14C spiked incinerator ash. We are enclosing this procedure. The modified leaching procedure consists of the addition of approximately 5 grams of ash per 20 milliliters of extraction fluid (a mixture of glacial n-8 acetic acid and water to a ph of 2.88). The solution is agitated vigorously for 4 hours. This slurry is centrifuged and the supernatant is analyzed for beta radioactivity using a calibrated Packard 460 CD or equivalent liquid scintillation counter with appropriate quench curve calibrating and corrections. Enclosed is the lower limit of detection in liquid scintillation counting of ash for 10 minute counts for the main , isotopes we would count. I 1) H-3 3 X 10-6 uCi/gm ) 2) C-14 3 X 10-6 uCi/gm other pure strong beta emitters would have similar or lower I MDA's. S-35 would be similar to C-14 MDA. I b) We confirm that ash generated during radioactive material incineration will be assessed to determine that it is non- radioactive prior to discarding the ash into ordinary trash. This will be determined by direct measurement of the ash or inferred from other measurements of the incinerator (e.g. wet scrubber and/or stack etc.). 1 Ouestion 4 | Previously, in a letter to the NRC dated June 17, 1993 BUMC 1 submitted calculations for 3H and 14C MPC calculations. Based on ' current information, calculations to demonstrate compliance for 3H and 14 C effluents into sanitary sewerage will be provided. We are providing hi and 14C solid radwaste data generated i over a year that woul.1 have been disposed of by commercisl ! radwaste burial. This activity is 35935 uCi of 3H and 23364 uCi ! of 14C. To be conservative these values of activity will be doubled and the resultant values used in the calculations | ' , ' ? . ( . 3H - 7.187E4 uCi 14C - 4.673E4 uCi The average monthly water flow at BUMC is 6.037E9 mL. The current 10 CFR Part 20 monthly 1.imits are: 3H - 1E-2 uCi/mL 14 C - 3E-4 uCi/mL Calculations: Fraction of Limit 3H 7.187E4 uCi = 1.19E-5 uCi/mL X 1 = 1.19 E-3 6.037E9mL 1E-2 uCi/mL 14C 4.673E4 uCi = 7.74E-6 uCi/mL X 1 = 2.58 E-2 6.037E9mL 3E-4 uCi/mL TOTAL 2.70 E-2 The contribution from radioactive research lab aqueous sink disposal will also be added in to demonstrate compliance. A review of our sink disposal records for 1992 and 1993 show the largest monthly dumps for 3H and 14 C respectively were 43737 uCi and 3974 uCi. These values will also be doubled and the results used in the calculations Fraction of Limit 3H 87474 uCi = 1.45E-5 uCi/mL X 1 = 1.45 E-3 6.037E9mL , 3E-4uci/mL 14C 7948 uCi = 1.32E-6 uCi/mL X 1 = 4.39 E-3 6.037E9mL 3E-4uci/mL TOTAL 5.84 E-3 Combining with the incinerator fraction 5.84 E-3 , + 2.70 E-2 | 3.28 E-2 Even if the highest monthly sink disposal values for each of the major isotopes disposed of during 1992 and 1993 are doubled and assumed to be disposed of during the same month with 1 years worth of solid 3H and 14C waste incinerated, the fraction of the allowable effluent concentration would be 0.622. incerely,i h C. Victor Evdokimoff, CHP Director Radiation Protection, BUMC enclosure , I - 3 Pt.261. App I 40 CFR Cli. 8 (T 192 f dition) favicenmental Protection Agency Pt. 261. 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