DISTRIBUTION LIST To be filled out by Document Author or person requesting document deletion

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4 DISTRIBUTION LIST To be filled out by Document Author or person requesting document deletion: Once approved, the new or revised document or the notice of deleted document(s) should be distributed to all persons identified below: ( ) All RP staff members ( X ) All holders of the following manual(s): SLAC Radioanalysis Laboratory Procedures ( ) The following individuals: November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 3

5 TABLE OF REVISIONS REVISION DATE SECTION(S) REASON FOR REVISION # 001 November 27, 2006 All Provide steps for the calibration process November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 4

6 TABLE OF CONTENTS Liquid Scintillation Counter Calibration Procedure 1 PURPOSE REFERENCES RESPONSIBILITIES Rad Lab Operator REP Manager PREREQUISITES PROCEDURES Self Normalization and Calibration Check Accuracy check Quench Curve Verification RECORDS ATTACHMENTS/FORMS Attachment 1: 2005 Annual Calibration Results (LSC)... 9 November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 5

7 1 PURPOSE As part of SLAC Radioanalysis Laboratory s (Rad Lab) Quality Assurance Controls, periodic calibration checks should be performed in order to verify system performance. Calibrations should be performed after system repairs or maintenance services. An annual calibration check should be performed at a minimum. The purpose of this procedure is to provide the necessary steps to perform the annual calibration. 2 REFERENCES 2.1 Packard Tri-Carb Operational Manuals 2.2 SLAC Rad Lab Manual, LSC Counting Procedure RE#009 3 RESPONSIBILITIES 3.1 Rad Lab Operator The Rad Lab Operator assigned to perform activities described in this chapter is responsible for: ensuring that prerequisites are met as required, performing calibrations, reporting any problems or unexpected events to the Radiological Environmental Protection (REP) Manager, generating and providing calibration reports to the REP Manager, and Performing other duties assigned by the REP Manager. 3.2 REP Manager The REP Manager is responsible for: ensuring that the activities in this chapter are conducted in accordance with this written procedure, assigning the tasks in this procedure to a qualified Operator, and November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 6

8 providing final approval or disapproval of all calibration results/reports. 4 PREREQUISITES 4.1 Must be familiar with DOS and Windows software menus. 4.2 Must be familiar with Rad Lab general sample analysis procedures. 4.3 Must be familiar with Liquid Scintillation Counting theory 4.4 Must be familiar with laboratory equipment (pipettes, scales, etc.) 5 PROCEDURES 5.1 Self Normalization and Calibration Check The Packard Tri-Carb Liquid Scintillation Counter (LSC) utilizes a Self- Normalization and Calibration protocol (SNC). The protocol is run daily when the LSC is in use and should be verified during the annual calibration. See Packard Instruments LSC manuals for specific details on the SNC protocol Run the SNC according to the Source Check section of the LSC Sample Counting Procedure (SLAC-I-760-2A39C-008) Efficiencies for the LSC should be compared to the parameters for small vials. If any of the above parameters are not satisfied, notify the Radioactive Environmental Protection (REP) Manager. Otherwise no further action regarding the SNC protocol is required. 5.2 Accuracy check Machine performance can be verified by checking its accuracy. This is accomplished by using a solution with a known specific activity. A stock solution from a NIST traceable standard can be made. Additional replicates should be made in order to reduce statistical error Create stock solution from a NIST traceable standard solution. A prepared solution with known specific activity can also be used Pipette 5 ml of the stock solution into a LSC vial Add 15 ml of Liquid scintillation cocktail November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 7

9 5.2.4 Count the sample(s) using the LSC Counting procedure (SLAC-I-760-2A39C-008). Assure that the samples are counted under LCW and Environmental protocols Determine the accuracy of the machine by comparing the output with the known activity of the sample(s). Perform any error calculation and statistical analysis as needed. Notify the REP Manager if the difference between the known activity and the reported activity is greater than 20%. 5.3 Quench Curve Verification The current quench curves are based on quenched 3 H standards. Rerun a similar set in order to validate the current quench curves. If a quench standard set cannot be located, replicates from a stock solution with known specific activity can be substituted. The replicates will have the same activity, but will contain varying amounts of quenching agent Load a quenched 3 H set into the LSC and count using LCW 30 minute count (Protocol 1) Plot tsie vs. absolute efficiency. For efficiency calculations, be sure to decay correct when using quenched 3 H standards Print the current quench curves (see Tri Carb manual for details). Compare the current quench curves with the quenched 3 H set. If the trends of the curves do not appear to match, notify the REP Manager. Otherwise replace the old quench curves with the new one and complete the calibration report. 6 RECORDS 6.1 Calibration results generated from this procedure must be documented into a report and submitted for approval. A signed copy will be filed in the Rad Lab archives. A sample calibration report has been provided (see attachment #1) for reference. 7 ATTACHMENTS/FORMS 7.1 Attachment 1: 2005 Annual Calibration Results (LSC) November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 8

10 7.1 Attachment 1: 2005 Annual Calibration Results (LSC) Attached are the results of the annual calibration performed on the Packard Tri-Carb Liquid Scintillation Counter (LSC) by Henry Tran and Henry Brogonia. As per the SLAC Rad Lab LSC Calibration Procedures a Self Normalization and Calibration (SNC) check, an accuracy check, and validation of quench curves were performed to assure SLAC Rad Lab Quality Assurance controls. The results of the three checks are summarized below. The Self-Normalization and Calibration Check was performed as per the SLAC Rad Lab LSC Calibration procedure. The efficiencies for 3 H and 14 C are 59.10% and 95.10% respectively, which are within machine specifications (Appendix A). The accuracy check results of the LSC are shown in Table 1 (below). Two 500 ml bottles of stock solution were prepared by H. Tran from a 3 H source with a specific activity of 6.2 E+05 pci/l (Decay corrected, Appendix B). 5 ml of the standard was diluted with 200 ml of water, yielding a specific activity of pci/l per bottle. Samples were prepared and counted using the routine LSC counting procedure. 5 ml of the stock solution was added by pipette into a LSC vial. 15 ml of cocktail fluid was then added. Two replicates from bottle #1 and #2 were counted on protocol 1 (30 minute count) and 13 (150 minute count). Protocol #1 LCW - 30 min Protocol #13 Environmental min Sample DPM Sample DPM 1A 213 1A 210 1B 234 1B 228 2A 203 2A 215 2B 214 2B 218 Average: 216 Average: 218 Bkg: 25 Bkg: 24 Net: 190 Net: 193 Pci/L pci/l: STD: STD: Ratio 1.14 Ratio 1.17 Table 1 The results show that the percent difference between the known activity and the reported activity is 17%, which is within the 20% range for quality assurance controls. The results of the quench curve validation are shown below. Two sets of quenched 3 H standards (Appendix C) were counted on protocol 1 (30 min count). Each quench standard set consists of 10 glass vials with solutions of equal activity. The amount of quenching November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 9

11 agent is the only difference between the vials. The efficiency was calculated based on the reported activity and the known activity of the quenched standards (Appendix D). The tsie vs. efficiency curves were compared against the original stored quench curve. The new quench curves are relatively consistent with the stored quench curve on the LSC (Figure 1, below). The results are also consistent with the 2004 annual calibration. t-sie Quench Curve Efficiency t-sie H H-3 Stored Quench Curve Figure 1. Quench curve validation. Old Quench A represents the quench curve currently stored on the LSC machine. The remaining curves are two separate quench standards, designated by their reference date. The new quench curves are consistent with the stored curve. No adjustment to the LSC is needed at this time. Another test was performed to verify the LSC s response to a quenching agent. Because the quenched standards in the quench curve validation were contained in glass vials, a similar check was needed in order to verify the quench response in polyethylene vials used for Rad Lab LSC samples. Two polyethylene vials, 1B and 2B from the stock solution created during the accuracy check, were used for this quench response check. A quenching agent was added to the vials and subsequently counted to verify a response to quench. The process of adding a quenching agent and counting was repeated twice. The results are shown in the Table (below). As expected the quench indicating parameter (tsie) varied with the concentration of the quenching agent. November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 10

12 Quench ID CPM (in ROI) DPM Efficiency tsie 1B B B B B B B B Table 2 Quench response check for polyethylene vials used in Rad Lab analysis. The Quench ID corresponds to the sample vial and the amount of quench added to each vial (ul of red food coloring). The table shows the increase in quenching agent shows a lowering of tsie, the quench indicating parameter. The result is a lower efficiencies for lower tsie values, which is expected. ( ) It was determined that no adjustment to the LSC was needed. ( ) The following adjustments have been completed and the LSC is operating within satisfactory conditions: ( ) The LSC is not performing within satisfactory conditions. Will require service from vendor. Copy Only Calibration performed by Date Approved by Date Attached: Appendix A: SNC Protocol, SNC Calibration Report Appendix B: Certificate of Standard Appendix C: Certificate of Quenched Standards Appendix D: Table of Quench curve validation results November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 11

13 Appendix A November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 12

14 Appendix B November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 13

15 Appendix C November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 14

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17 Appendix D Quench ID CPM (in ROI) DPM Efficiency SIS tsie UG UG UG UG UG UG UG UG UG UG AX BX CX DX EX FX GX HX IX JX Data results from the quench curve validation. The quench ID corresponds to the reference date on the standard. For each set, vials are placed in order by increasing quench. Increasing the quench would correspond to a decreasing tsie, which is the quench indicating parameter used for the counting process. Efficiency vs. tsie is plotted and compared to original quench curve. As the trends for all curves appear to be similar, no adjustment in the LSC is required at this time. November 27, 2006 SLAC-I-760-2A39C-013-R-001 Page 16