Document: NRC Regulatory Guide
Document ID: 535957c7-1203-410d-b709-8e4d381f00de
Document Type: regulatory_guide
Title: Measurements of Radionuclides in the Environment, Analysis of I-131 in Milk
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML1335/ML13350A246.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.3
CFR Part: 
CFR Title: 

Content:
phase in the first separatory funnel and reextract. Combine organic phases and discard aqueous phase. , 13. Add 25 ml H20 and 10 drops of freshly prepared IM NaHSO 3 to the separatory funnelcontaining the combined CC14 and shake. Equilibrate for.. 2 minutes. Discard organic (lower) phase. (Note 6) 14. Transfer the aqueous (upper) phase into a clean 50-ml centrifuge tube and add I ml of conc. HNO3 and 10 ml of PdCI2 solution. Stir and let stand for 5 minutes. 15. Centrifuge Pdl2 precipitate discarding supernate. Wash precipitate by. stirring with 10 ml of H2 0. 16. Using a filter funnel setup similar to that (Teflon or polyethylene - nylon) described in HASL 300. "Procedure Manual'" USAEC, filter with suction through a tared glass fiber paper (2.8 cm diameter), using a water wash bottle to effect the transfer. (Note 7) 17. Dry precipitate for 20 minutes in an ovenset at *.I10C and weigh to the nearest 0.1 milligram. (Alternatively, the sample may be dried on a hot * plate at low heat for about 30 minutes.) .18. Mount the precipitate on a nylon disc, cover with:• Mylar (1/4 mil thick), and fasten with ring. (This .procedure is described in HASL 300.) j 19. Count in a low-background counter for I0 0%1 minutes. 20. If net counting rate of sample is greater than 0.3 cpm. recount after 7-8 days. 21. Calculate as picocuries 1-131 per liter of milk at time of sampling. Notes I. This is most easily accomplished by using a polyethylene squirt bottle to dispense the NaOCI. 2. Resin should be very light straw color after NaOCI extraction, if not light colored, the NaOCI is below strength, and a fresh solution should be obtained. Commercial grade Clo.rox has been found to be adequate. 3. Add the acid slowly with stirring until the vigorous reaction subsides. Perform in well ventilated hood. 4. Proceed with caution in this step. Excessive gas formation during the extraction can cause the stopcock or cap on the separatory funnel to "pop" with consequent loss of samp!e. Start by