ML24235A082
| ML24235A082 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 08/10/2024 |
| From: | Allan Barker Omaha Public Power District |
| To: | Document Control Desk, Office of Nuclear Material Safety and Safeguards, Office of Nuclear Reactor Regulation |
| References | |
| EPID L-2024-DFR-0002, UC-24-0009 | |
| Download: ML24235A082 (1) | |
Text
Omaha Public Power District UC-24-0009 August10,2024 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Fort Calhoun Station (FCS), Unit 1 Renewed Facility Operating License No. DPR-40 NRC Docket No. 50-285 Fort Calhoun Station
- Independent Spent Fuel Storage Installation NRC Docket No.72-054 10 CFR 50.90 10 CFR 50.82
Subject:
Response to FORT CALHOUN STATION, UNIT NO. 1 - PHASE 1 FINAL STATUS SURVEY REPORT TO SUPPORT APPROVED LICENSE TERMINATION PLAN -
REQUEST FOR ADDITIONAL INFORMATION (EPID L-2024-DFR-0002) JULY 8, 2024 (ML24180A208).
References:
- 1.
Letter from OPPD (M. Fisher) to USNRC (Document Control Desk), "License Amendment Request (LAR) 21-01 : Revised Fort Calhoun Station License to Add License Condition 3.D to include License Termination Plan Requirements," dated August 3, 2021 (UC-21-0005) (ML21271A143)
- 2.
Letter from NRC to OPPD (T. Via), "Fort Calhoun Station Unit 1 - Issuance of Amendment to Renewed Facility License to Add License Condition to Include License Termination Plan Requirements (EPID L-2021 -LIT-0000)," dated January 31, 2024 (ML24019A167)
- 3.
Letter from OPPD (A. Barker) to USNRC (Document Control Desk), "Fort Calhoun Station, Unit 1 - Phase 1 Final Status Survey Report to Support Approved License Termination Plan," dated April 17, 2024 (LIC-24-0006) (ML24114A232)
- 4.
Letter from NRC to OPPD (A. Barker), "Fort Calhoun Station, Unit No. 1 - Phase 1 Final Status Survey Report to Support Approved License Termination Plan - Request for Additional Information (EPID L-2024-DFR-0002)," dated July 8, 2024 (ML24180A208)
By letter dated August 3, 2021 (Reference 1 ), Omaha Public Power District (OPPD) submitted a License Amendment Request (LAR) to add a license condition, 3.0, to include License Termination Plan Requirements.
444 S 16th Street Mall
- Omaha, NE 68102-224 7 lMll.onll.N1 MfH f00.4l OPPOIFUWl"I'
~
U. S. Nuclear Regulatory Commission LIC-24-0009 Page 2 On January 31, 2024 (Reference 2), the NRC provided OPPD with an SER and issuance of Amendment to Renewed Facility License to include the License Termination Plan (LTP) requirements. By letter dated April 17, 2024 (Reference 3), OPPD submitted the Final Status Survey (FSS) report and accompanying data for the first phase of FSS records in a phased approach to eventual partial site release of Fort Calhoun Station. On July 8, 2024, the NRC provided Fort Calhoun Station with a Request for Additional Information (RAI) regarding the data contained in the Phase 1 Final Status Survey Report (Reference 4 ). of this letter provides the responses to the RAls.
This letter contains no regulatory commitments.
If you should have any questions regarding this submittal or require additional information, please contact Mrs. Andrea K. Barker, CHP - Regulatory Assurance and Emergency Planning Manager at (531) 226-6051.
Respectfully,
~
Andrea K. Barker, CHP, MHP Regulatory Assurance and Emergency Planning Manager AKB/akb Attachments: 1. Response to Request for Additional Information
- 2. Canberra Geometry Composer Report
- 3. Ludlum Model 44-10 Detector Sensitivity Analysis c:
J. D. Moninger, NRC Regional Administrator, Region IV J. D. Parrott, NRC Senior Project Manager S. Anderson, NRC Health Physicist, Region IV
LIC-24-0009 ATTACHMENT 1 Response to NRC Request for Additional Information for Fort Calhoun Station Final Status Survey Final Report, Phase 1 8 Pages Follow
Response to NRC Request for Additional Information for Fort Calhoun Station Final Status Survey Final Report, Phase 1 Fort Calhoun Station (FCS) provides the following responses:
RAI-01-01 Comment:
Instrument sensitivity and laboratory sample analysis should be capable of measuring residual radioactivity less than the DCGLs [derived concentration guideline levels]. The FSSFR [Final Status Survey Final Report] and Survey Unit Release Reports (SURRs) should explicitly state the instrument and sample analysis minimum detectable concentrations (MDC) determined for the survey unit. Where a posteriori MDCs for instruments are used, include the variables, and show the calculations of the MDCs.
Request:
(1) To facilitate validation that the instrument and method sensitivities are less than the appropriate DCGLs, provide the following:
a) The instrument MDCs directly comparable to the DCGLs for survey instruments used in Phase I OLA [ open land area] final status surveys.
b) The onsite and off-site laboratory sensitivities for each sample result in units directly comparable to the DCGLs.
c)
The /SOCS [In Situ Object Counting System} measurement system MDC, including inputs used for its calculation.
(2) Section 4.6.2 of the FSSFR, "Detector Sensitivities" discussed the determination of the gamma scan MDCR [minimum detectable count rate} referencing FC-19-006, "Ludlum Model 44-10 Detector Sensitivity. " The detector used for scanning the survey units was the Ludlum Model 44-20. To evaluate the appropriateness of this procedure to the Ludlum 44-20, the NRC staff requests a copy of FC-19-006.
Response
(l)(a):
The a priori MDCs for Ludlum Model 44-20 detectors were calculated using the guidance in NUREG-1507, "Minimum Detectable Concentrations with Typical Radiation Survey for Instruments for Various Contaminants and Field Conditions." The MDC calculation was modified by substituting the Count Rate to Exposure Rate Ratio (CPMR) for the 44-20 in place of the CPMR for the 44-10.
The value ofCPMR used for the 44-20 was 2,300 cpm per µR/hr. This value assumes a 100% Cs-137 source term and is taken from the Ludlum 44-20 technical manual and NUREG-1507. The use of the CPMR value for a 100% Cs-137 source term is conservative as Cs-137 has a higher response factor than Co-60.
The Exposure Rate to Concentration Ratio (ERC) in µR/hr per pCi/g was taken from FC-19-006, "Ludlum Model 44-10 Detector Sensitivity." This value is determined by MicroShield modeling of a concentration of activity in soil and determining the corresponding exposure rate in µR/hr. A value of 0.3033 µR/hr per pCi/g was used to calculate the 44-20 MDC. This is based on a source to detector end cap of2 inches and a 95% Cs-137 & 5% Co-60 nuclide fraction. The use of the selected ERC is conservative as the source to detector distance calculation in FC-19-006 actually uses the distance to the mid-point of a 2" detector crystal. This results in the total distance modeled being 3" as opposed to the NUREG-1507 methodology of modeling the distance to the detector end cap.
Page 1 of 8
Response to NRC Request for Additional Information for Fort Calhoun Station Final Status Survey Final Report, Phase 1 The other terms used in the 44-20 MDC calculations were as follows:
Scan Speed: 0.25 mis Area of Interest: 0.5 m scan width Background Count Rate: 76,000 cpm Index of Sensitivity ( d'): 1.38 Surveyor efficiency (p): 0.75 Observation Interval: 2 The surveyor efficiency of0.75 was based on the survey being performed using gamma detection instrumentation coupled to a Global Positioning System (GPS) unit, with the data being subsequently post-processed using Geographic Information System (GIS) software.
Alarm set-points for gross activity were set at the daily calculated average of the background plus the associated MDCRsurveyor, For the Model 44-20, the MDCRsurveyor should not exceed 2,406 cpm and background cannot exceed 76,000 cpm to achieve a MDCscan of3.47 pCi/g (the gross activity DCGL).
The Phase 1 SURRs will be revised to include instrument MDCs directly comparable to DCGLs.
(I )(b ):
The on-site and off-site laboratory sensitivities for each sample result, in pCi/g, will be added to the SURRs.
(l)(c):
The SURRs will be revised to include the ISOCS system MDCs for each measurement in pCi/g. The MDCs were calculated by the Genie gamma spectroscopy software. The ISOCS results were reported in pCi/m2 and converted into pCi/g based on a 1 m2 field of view (FOY) and a source thickness of 6 inches.
A soil density of 1.5 g/cm3 was used, which is consistent with the density used in the calculations in Chapter 6 of the LTP. The ISOCS system geometries used for the investigation measurements are included in Attachment 2. The FOY for the geometry used for the investigations was 1.2 m2, which results in a conservative calculation of the results in pCi/g.
(2):
A copy of FC-19-006 is provided in Attachment 3.
A TSD specifically for the Ludlum Model 44-20 is in preparation.
RAI-01-02 ISOCS Application in OLA Survey Units Comment:
The FSSFR should explicitly state how ISOCS is being applied to open land area surveys.
Request:
Explain how the /SOCS protocol was applied in open land area FSSs and how these measurements were used in the final evaluation of the survey unit.
Page 2 of 8
Response to NRC Request for Additional Information for Fort Calhoun Station Final Status Survey Final Report, Phase 1
Response
The FSSFR will be revised to state how ISOCS was applied in open land area surveys.
The use of ISOCS in the FSS of open land areas was limited to the investigation of small areas of elevated activity found during scan surveys and post-processing.
When scan alarms were prevalent using the alarm set point ofMDCRsurveyor plus average background, a statistical parameter-based value of three standard deviations was used to evaluate gamma walkover data to locate suspect small areas of elevated activity, per L TP Section 5.4.1.1. Once suspected areas were located, ISOCS measurements or soil samples were collected to investigate. If the ISOCS identified any radionuclides of concern (ROC), then a soil sample was collected for further investigation. In some cases, when scan alarms were present, but no reading exceeded the three standard deviation criteria, no investigational samples were collected.
The ISOCS measurements are not considered in the final evaluation of the survey unit (i.e., dose), only as qualitative measurements to guide further investigation.
RAI-01-03 Reclassification of Survey Units Comment:
A justification for maintaining a Class 3 classification, rather than reclassifying the survey units with one or more judgmental samples/measurements exceeding 50% of the OpDCGL, is needed.
Request:
Explain why the following survey units, with judgmental samples having an SOF [sum of fractions] of greater than 50% of the OpDCGL were not reclassified.
- SU 8103 - two judgmental samples (8103X-3-FJ-GGDX-018 and 8103X-3-FJ-GGDX-031) with an SOF greater than 0.5.
- SU 8109-three judgmental samples (8109X-3-FJ-GGDX-021, 8109X-3-FJ-GGDX-032, and 8109X-3-FJ-GGDX-040) with an SOF greater than 0.5.
- SU 8305 - two judgmental samples (8305X-3-FJ-GGDX-017 and 8305X-3-FJ-GGDX-037) with an SOF greater than 0.5.
Response
The listed judgmental samples are all investigational ISOCS measurements. The intent of the ISOCS measurements was to verify that the scan alarm was due to plant-related ROCs and not NORM. Samples were collected at these ISOCS locations and the SOF for the samples showed that all were less than 0.5.
The inclusion of the calculated ISOCS SOFs was in error and they will be removed in the revised SURRs.
RAI-01-04 Maximum SOF for Random and Judgmental Sample/Measurement Comment:
The maximum SOF for survey units 8103 and 8109 throughout the SURRs are inconsistent.
Page 3 of 8
Response to NRC Request for Additional Information for Fort Calhoun Station Final Status Survey Final Report, Phase I Request:
Explain the inconsistency in the maximum SOF for judgmental sample/measurements between the values identified in the executive summary and Table 7-4 for Survey Units 8103 and 8109.
Response
The executive summary states the maximum Operational SOF (OpSOF) for random and judgmental soil samples, however the incorrect maximum OpSOF was used for the 8103 and 8109 SURRs. The correct maximum OpSOF for soil is provided in Table 7-2 in each SURR. The SURRs for 8103 and 8109 will be revised to ensure that the maximum OpSOF from random and judgmental soil samples is consistently reported.
RAI-01-05 C-14 Analysis Comment:
The licensee does not discuss how C-14 is accounted for in judgmental measurements taken with ISOCS.
Request:
a)
Clarify for which samples (random, systematic, judgment, or all) the I 00% analysis criterion for HTDs applies.
b) Explain how C-14 was accounted/or in conditions where ]SOCS measurements were taken without a corresponding soil sampling.
c) Justify the use of a zero value for C-14 in the calculation of the judgmental sample SOF values, as shown in Table 7-4, when no C-14 analysis was done, and no surrogate ratio was used.
Response
As described in the response to RAI-01-03, the inclusion of the calculated ISOCS SOFs, which takes into account the full list ofROC for soil (which includes C-14), was in error and they will be removed in the revised SURRs. C-14 is a hard-to-detect (HTD) radionuclide and is not analyzed by the ISOCS. The purpose of the ISOCS measurements was to qualitatively identify plant-related ROC, therefore the granularity of including ISOCS SOF was in error. The intent was to show which radionuclides were positively identified, which should have been presented outside of the SOF table.
(a):
The 100% analysis criterion for C-14 applies to all soil samples (random, systematic, and judgmental). It is not applicable to in situ, qualitative investigational measurements.
(b):
In the cases where the ISOCS investigational measurements did not positively identify an ROC, the scan alarm was considered to be unverified, and no further investigation (i.e., soil sampling) was necessary.
For the qualitative measurements, it was unnecessary to account for C-14.
Page 4 of 8
Response to NRC Request for Additional Information for Fort Calhoun Station Final Status Survey Final Report, Phase I (c):
The ISOCS measurements were qualitative measurements collected to guide further investigation. C-14, an HTD ROC, is not analyzed by the ISOCS. As such, zero values were placed in the SOF table for all ISOCS measurements. However, as stated above, including the SOF for ISOCS measurements was an error and will be removed. The intent was to show positive detections of easy-to-detect ROC.
RAI-01-06 Relative Shift Comment:
The relative shift derived in Equation 5-1 of the SURRs, "Relative Shift," does not equate to the relative shift calculated from data in Table 3-1 of the SURRs, which contains statistical quantities for Cs-137 and Co-60 from characterization surveys. Additionally, there appears to be a discrepancy in the stated source of characterization data used as the basis for the relative shift in several SURRs.
Request:
a) Clarify which survey unit specific or survey area characterization data was used to obtain relative shift for each survey unit.
b) Furnish a summary of survey unit specific characterization data used to obtain statistical quantities in Table 3-1.
c) Explain the source of the lower bound of the gray region (LBGR) and the standard deviation used as input to Equation 5-1 of the SURRs.
Response
(a):
During open land characterization, survey areas were characterized (e.g., 8100, 8200, 8300, etc.). The relative shift calculation for each survey unit, within a survey area, was calculated by using a subset population of soil samples collected from the overall survey area. Each subset population of samples fell within, and are representative of, the survey unit. In some cases ( e.g., survey unit 8101 ), field conditions at the time of initial characterization did not allow for the collection of samples. In these instances, the full data set for the survey area was detailed in the SURR and used for the relative shift calculation.
(b):
The source of characterization data used to calculate relative shifts is FC-20-012, "Fort Calhoun Station Decommissioning Project Radiological Characterization Report," which is largely reproduced as Chapter 2 of the FCS L TP. The radionuclide data used to calculate the relative shift for an individual survey unit, included Co-60, Cs-137 and Eu-152. This differs from Table 3-1 within the SURRs which only shows statistical data from Co-60 and Cs-137. Any sample that was sent for off-site analysis that was part of the survey unit subset sample population was presented in Table 3-2. Descriptions of the survey unit specific relative shifts and the characterization samples used for the calculation of the relative shifts will be added to the SURRs. Additionally, Eu-152 data will be added to the Table 3-1, to facilitate the reproducibility of the relative shift from the data contained within each SURR.
(c):
The LBGR and standard deviation used for the calculation of relative shift are taken from the survey area or survey unit characterization results, expressed in terms of sum of fractions (SOF), in accordance with Section 4.6.4.G of procedure FCSD-RA-LT-302, "Final Status Survey Sample Plan Development." The Page 5 of 8
Response to NRC Request for Additional Information for Fort Calhoun Station Final Status Survey Final Report, Phase 1 upper bound of the gray region is equal to 1 under the unity rule, the LBGR is the mean of the characterization data set expressed as an SOF, and the standard deviation is the weighted standard deviation of the characterization data set in accordance with the equation in Section 4.6.4.G.4 of procedure FCSD-RA-L T-302.
RAI-01-07 Scan Action Levels Comment:
The SURR should include a description of the derivation of scan action levels ( cpm} and how licensee delineates when judgmental samples are collected and analyzed following scan alarms.
Request:
a) Explain how the scan action levels (cpm) were derived.
b) Explain why some areas had scan alarms but no judgmental samples were taken.
Response
(a):
The action levels for scanning in the Class 3 open land area survey units are based on the mean background of the area to be surveyed plus the associated MDCRsurveyor-The use of the MDCRsurveyor ensures that the action levels are greater than the MDCscan-When scan alarms were prevalent using the alarm set point of MDCRsurveyor plus average background, a statistical parameter-based value of three standard deviations was used to evaluate gamma walkover data to locate suspect small areas of elevated activity, per LTP Section 5.4.1.1. Once suspected areas have been located, ISOCS measurements or soil samples were collected to investigate. If the ISOCS identified any ROC, then a soil sample was collected for further investigation.
(b):
In some cases, when scan alarms were present but no reading exceeded the three standard deviation criterion, no judgmental samples were collected. In the case of the Class 3 open land area survey units, the sample analyses (random and judgmental) have indicated that the scan readings above the investigation levels are due to the presence of NORM. The only ROC identified in any sample or ISOCS measurement was Cs-137. The detected, low-level Cs-137 concentrations were consistent with background due to fallout from atmospheric weapons testing.
RAI-01-08 Scan Area Locations Comment:
There is apparent inconsistency in how the scan areas and random sample locations are represented in Table 7-1, "Synopsis of Scan Results" and Figure 16-1 (scan and/or sample location map) of each SURR. NRC staff were unable to verify the location of random samples and scan locations in some instances.
Page 6 of 8
Response to NRC Request for Additional Information for Fort Calhoun Station Final Status Survey Final Report, Phase 1 Request:
a) For each survey unit listed above, provide figure(s) displaying all scan areas and the location of random samples taken in each survey unit (i.e. Figure 16-1).
b) Clarify if 1 m2 scans were taken around each random sample location in each survey unit. If not, explain these inconsistencies.
c) Clarify the various scan area designations listed in Table 7-1 of each survey unit and the meaning of each identifier (whether it refers to a gamma walkover scan area, a 1 m2 scan area surrounding a random sample, or something else).
Response
(a):
Figures will be provided in the SURRs that accurately display all scan areas and the locations of random samples within each survey unit.
(b):
1 m2 scans were not performed around random samples for every survey unit, as random samples were consistently located within the larger gamma walkover scan areas. If random samples fell outside of the larger gamma walkover scan areas, a minimum of 1 m2 was scanned around them. Additionally, for judgmental samples, 1 m2 scans were performed to verify the + 3 standard deviation investigation points.
Descriptions of any applicable 1 m2 scans around any sample not already located within a bigger scan area, will be provided within the SURRs.
(c):
Clarity and consistency will be provided for scan area designations, Table 7-1, for the SURRs.
RAI-01-09 Background Measurements Comment:
The background measurement procedure was inconsistent between open land area survey units.
Request:
Justify the deviation in the background measurement procedure/or Survey Units 8103 and 8106.
Response
Background measurements are taken from a height of 6 inches with the Nal detector rather than 2 inches, in accordance with site procedures. The typos in the SURRs will be corrected to reflect the procedures.
Page 7 of 8
Response to NRC Request for Additional Information for Fort Calhoun Station Final Status Survey Final Report, Phase 1 Editorial Issue (1) Survey units 8103 and 8106 did not have axis labels for the retrospective power curve. Given that the curves from the other ten survey units are labeled, it is assumed that the labels are the same for these survey units. Please confirm that this is the case.
Response
The axis labels for the retrospective power curves presented in the SURRs for survey units 8103 and 8106 are the same of the other 10 survey units that are labeled. The retrospective power curves for survey units 8103 and 8106 will be corrected with appropriate axis labels and be included in the revisions to the SURRs.
Page 8 of8
ATTACHMENT 2 Canberra Geometry Composer Report 6 Pages Follow
Geometry Composer Report CANBERRA Date:
==
Description:==
Comment:
File Name:
Software:
Template:
Detector:
Collimator:
Environment:
Integration:
No.
1 2
3 4
5 6
7 8
9 10 11 12 13 Tuesday, July 23, 2024 - 18:24:32 lm Soil 90d lm Soil 90d C:\\GENIE2K\\isocs\\data \\GEOMETRY\\ln-Situ\\CIRCULAR_PLANE\\lm Soil 90d.geo ISOCS CIRCULAR_PLANE, Version: (default) 13687 50mm-90d new (newISOCS 50mm side 90deg collimation [large hole collimator])
Temperature = 22 °C, Pressure = 760 mm Hg, Relative Humidity = 30%
Convergence = 1.00%, MDRPN = 24 (16), CRPN = 24 (16)
Dimensions (m)
Dwriptlon d.1 d.2 d.3 cL4 d.S d.l Matarlal Side Walls 0
1.1938 none Layer 1 0.15 dirt3 Layer 2 0
<none>
Layer 3 0
<none>
Layer4 0
<none>
Layer 5 0
<none>
Layer 6 0
<none>
Layer 7 0
<none>
Layer 8 0
<none>
Layer 9 0
<none>
Layer 10 0
<none>
Absorber!
none Absorber2 Danlity 1.5 14 Source-Detector 0.5969 0
0 0
0 59.5 351.9 1332.5 63.3 391.7 1460.7 I CIIDJlMt w List of energies for efficiency curve generation 88.0 122.1 143.8 165.9 583.2 661.7 898.0 911.6 1764.5 1836.1 X
z Page 1 of 2 185.7 1001.0 238.6 1173.2 D* ------,-f H.J
,d
- bl.Cone.
1.00
Geometry Composer Report Date:
==
Description:==
Comment:
File Name:
Software:
Template:
Tuesday, July 23, 2024 - 18:24:32 lm Soil 90d lm Soil 90d C:\\GENIE2K\\isocs\\data\\GEOMETRY\\ln-Situ\\CIRCULAR_PLANE\\lm Soil 90d.geo ISOCS CIRCULAR_PLANE, Version: (default)
Page 2 of 2 CANBERRA
ISOCS/LabSOCS File:
ISOCS/LabSOCS Time:
ISOCS/LABSOCS RESULTS C:\\GENIE2K\\isocs\\data\\GEOMETRY\\In-Situ\\CIRCULAR PLANE\\lm Soil 90 Fri Jan 6 11:20:45 2023 Template:
CIRCULAR PLANE Geom
Description:
lM SOIL 90D Comment:
ISOCS:lM SOIL 900 Detector:
13687 Collimator:
50MM-90D NEW Convergence:
1.00 %
Area [Sq Meters]:
1.1193e+00 (C)
Mass [Grams]:
2.5185e+05 (C)
Length [Meters]:
not used (C) = Value calculated by ISOCS (U) = Value modified by user Energy 59.50 63.30 88.00 122.10 143.80 165.90 185.70 238.60 351.90 391.70 583.20 661.65 898.00 911.60 1001.00 1173.20 1332.50 1460. 70 1764.50 1836.10 Efficiency 4.52634e-05 4.66369e-05 5.26801e-05 5.35237e-05 5.29454e-05 5.17060e-05 5.02744e-05 4.47638e-05 3.75802e-05 3.58583e-05 3.04218e-05 2.89544e-05 2.60240e-05 2.58369e-05 2.50183e-05 2.34781e-05 2.20463e-05 2.09937e-05 1.88173e-05 l.84097e-05
%Uncertainty 10.0 10.0 10.0 10.0 10.0 9.0 8.0 8.0 8.0
- 8. 0 6.0 6.0 5.0
- 4. 0 4.0 4.0
- 4. 0 4.0 4.0 4.0
%Convergence
-0.117475
-0.119724
-0.113795
-0.105105
-0.099149
-0.090985
-0.077601
-0.031946 0.077266 0.104387 0.182731 0.196877 0.218870 0.219935 0.226118 0.232308 0.234239 0.232898 0.231231 0.231009 Final# of Voxels 10065 10065 10065 10065 10065 10065 10065 10065 10065 10065 10065 10065 10065 10065 10065 10065 10065 10065 10065 10065
Geometry Composer Report Date:
==
Description:==
Comment:
File Name:
Software:
Template:
Detector:
Collimator:
Environment:
Integration:
No.
1 2
3 4
5 6
7 8
9 10 11 12 13 Tuesday, July 23, 2024 - 18:41:51 lm Soil 90d lm Soil 90d C:\\GENIE2K\\isocs\\data\\GEOMETRY\\ln-Situ\\CIRCULAR_PLANE\\lm Soil 90d.geo
!SOCS CIRCULAR_PLANE, Version: (default) 13693 50mm-90d new (newISOCS 50mm side 90deg collimation [large hole collimator])
Temperature = 22 °C, Pressure = 760 mm Hg, Relative Humidity = 30%
Convergence = 1.00%, MDRPN = 24 (16), CRPN = 24 (16)
Dimensions (m)
Dacrlptlon d,1 d,2 d.3 d.4 d.S d.l Side Walls 0
1.1938 none Layer 1 0.1524 dirt3 Layer 2 0
none Layer 3 0
none Layer 4 0
none Layer 5 0
none Layer 6 0
none Layer 7 0
none Layer 8 0
none Layer 9 0
none Layer 10 0
none Absorber!
Ii' none Absorber2 none 14 Source-Detector 0.5969 0
0 0
0 59.5 351.9 1332.5 63.3 391.7 1460.7 I CIIIEIJLMW List of energies for efficiency curve generation 88.0 122.1 143.8 165.9 583.2 661.7 898.0 911.6 1764.5 1836.0 A
Page 1 of 2 185.7 1001.0 CANBERRA Deflllty 1.5 238.6 1173.2 14.3
,d Rel.Cone.
1.00 I
Geometry Composer Report Date:
==
Description:==
Comment:
File Name:
Software:
Template:
Tuesday, July 23, 2024 - 18:41:51 lm Soil 90d lm Soil 90d C:\\GENIE2K\\isocs\\data\\GEOMETRY\\ln-Situ\\CIRCULAR_PLANE\\lm Soil 90d.geo
!SOCS CIRCULAR_PLANE, Version: (default)
Page 2 of 2 CANBERRA
ISOCS/LabSOCS File:
ISOCS/LabSOCS Time:
ISOCS/LABSOCS RESULTS C:\\GENIE2K\\isocs\\data\\GEOMETRY\\In-Situ\\CIRCULAR PLANE\\lm Soil 90 Tue Jul 23 18:42:27 2024 Template:
CIRCULAR PLANE Geom
Description:
lM SOIL 900 Comment:
ISOCS:lM SOIL 900 Detector:
13693 Collimator:
50MM-90D NEW Convergence:
1.00 %
Area [Sq Meters]:
l.1193e+00 (C)
Mass [Grams]:
2.4735e+05 (C)
Length [Meters]:
not used (C) = Value calculated by ISOCS (U) = Value modified by user Energy 59.54 63.30 88.03 122.06 143.80 165.85 185.70 238.60 351.90 391.69 583.20 661.65 898.02 911. 60 1001.00 1173.22 1332.49 1460.70 1764.50 1836.01 Efficiency 4.63539e-05 4.77732e-05 5.37838e-05 5.44117e-05 5.35121e-05 5.20289e-05 5.04109e-05 4.45058e-05 3.67580e-05 3.49260e-05 2.95093e-05 2.80429e-05 2.48458e-05 2.46422e-05 2.37644e-05 2.22782e-05 2.09769e-05 l.99568e-05 l.78452e-05 l.74467e-05
%Uncertainty 10.0 10.0 10.0 10.0 10.0 8.0 8.0 8.0
- 8. 0 8.0 6.0 6.0 6.0 4.0 4.0 4.0 4.0 4.0 4.0 4.0
%Convergence 0.028512 0.020629 0.004528
-0.008854
-0.012844
-0.003823 0.010475 0.046781 0.070531 0.067892 0.041951 0.032282 0.013592 0.013295 0.009866 0.004176 0.001018
-0.000652
-0.004608
-0.004601 Final# of Voxels 10350 10350 10350 10350 10350 10350 10350 10350 10350 10350 10350 10350 10350 10350 10350 10350 10350 10350 10350 10350
ATTACHMENT 3 Ludlum Model 44-10 Detector Sensitivity Analysis 48 Pages Follow
FC-19-006 Revision 0 Ludlum Model 44-10 Detector Sensitivity Prepared By.
Reviewed By:
D FC-19-008 RevlaionO Pp1of4'
1.0 ISSUE STATEMENT Ludlum 10 detectors are co used o radionu po nstrume anal 10 det cto to qua electors and de ermine Conce C) at the Fort Calhoun Sta ion (FCS 60.nd C 137 a Hy pre n a radio ctive con am nation.
2.0 BACKGROUND
STATEMENT Published ensitivity fo ttie Ludlum 1 O detector i listed in e m nu acture s literature a 900 c
µRJhr or C -137. Ta le.7of NUREG-1575 r the Co,,60 and C 137 n it v y for a 5.08 by 5.08 cm Nal detector as 430 and 900 cpm/
re p ively. A tudy was rform at h Rancho S co ucl Gen-.--...,
..,.,....-. Sta ion (RS GS) o con irm them nufact rer's Ii erature Th v lue derived from th study will b u ed in this paper a th y were deri d mp*ncalfy.
3.0 METHODOLOGY 3.1 Qu r th re ponse of the vendo Nat dete or o Cs-137 and Co-60 sources based on a udy pe orm at a ou r1 actor decomml ton*ng.
3.2 Iden lfy de eta e
- ual II con n ion for Co- 0 nd C 137 rad onuci de at the FCS site loca on where h soil nuclide fraction are consi nt with th d ta provided In thi document. Th evaluati n nc ude consideration for usi Co-60 or C
7 a urrog radionud"de.
4.0 ASSUMPTIONS
.1 T. conclu on o this p per are r ited to 2 5.08 by 5.08 cm N I
5.0 CONCLUSION
S
- 5.
Thi per v lu 51uvi1tv ft Ludlum odel O 2 5.08 6.0 CALCULATIONS 6.1.1 op n I nd areas as n of b
. scan a function of
- ure of Co-60 nd b d rived or
Ludlum Model 44-10 Deteclor FC-19-006 Revision 0 3of48 the delector me and the distance from the source face to the detector centef1lne (located at 2.54 an beyond the detector end cap).
The evaluation process to detennine detector response factors for C.-137 and Co-80 are pmvlded in Attachment 8.1. The results are presented in Tabte 1.0 below.
Table 1.0 n
F ctors for Ludlum odel 44-10 De ctor Source to o.tector Diatance(om)
MlcroshielcP o.rivedµR/h Co-60 Cs-137 2412 6.032 128.1 1.508 32.01 8.001 "1-10 (5.08 x 5.0I an)
The average C.-137 f8SPOn&e fador for the 44-10 Nal detedot is 941.0 cpm/µRA,. The vafue is consiatent with the results fOt.l1d In NUREG-1575 Table
- e. 7. The a.-age Co-80 value for the 44-10 Nal detector is -433 cpm/µRlh. Thia result Is also oonsislent with the value reported tn Tal;tle 8.7 of NUREG-1575. It ls Important to note that the principle gamma energy response for Ce-137 and Co-80 are in
- and from a pon source. The Nal detectors response will be greater for the lower ~
gammas resulting from the ecatter'n,g procesw associated wtlh the nucldes being distributed In soH media.
6.2 Model for Oetermjnation of Nat Detector Soil MDC:
8.2.1 The MARSSIM suggested scan speed of 0.5 m/a is uaed with the elevated (IOlf) area of Interest being 0.196 m2 that relates to contaminants in a 50 cm diameter region that is 15 an deep. The depth is consistent with the EPA and NRC definition of surface soils. The soil density is assumed at 1.6 g/em' and the compoeitlon used for the Micn>Shield111 custom material soil model la compoMd of &11icon oxide (sand). Recent acquiaition of surface and subsurface soil sampling at the FCS indicate construction grade soils con8isllng prlmarlly of loamy clay. sand and gnwels that are of similar denlity valuet. The Nal detector height from the surface is varied and asaumes surface to detector center distances of 3.0 (7.62 cm). 4.0 (10.16 cm) and 6.0 (15.24 cm) Inches (2.0, 3.0. and 5.0 inches from the detector end cap). Theee distances povlde reasonable estimates of the variation of detector height above the during
- ng open1tions. The 50-centJmeter diameter
L area is selected
........,,..,.,a dence ti e of one second scan ra 0.5
- at so I sea can re dee econd. To scan measureme e MOC v I e
odel I
te from Table d
fo ea nuclide. A urveyo of O 5 an a e
... nrv,,~
ed in th MOC determination.
Incl ion o the s f the surveyors to both listen
- or th *nstrument c 1vetitia;auo wing instrument a arm a d
Uy, the 50 cm diame erb 5.
u of h suspect radionuctides.
6.3 s0*I Rad*onuciide Distribution 6.3.1 so*1 nuclide fraction for Co-60 is 10 with Cs-137 compns ng the remaming fracbon. Val ud nta nlng 100 Co-60 orCs-137.
so I MOC va ues ed *n this paper may be ucllde fraction d' *
+/-2 3/4 ) are no ed. 0th so1 1DOEUt10n nuunau.
nt action I vels will be d loped based o 6.4 icroShield,... Code R ns and Derived DC Values 6.4.1 Sp MicroShieldlU code runs (Se Alta ed to detennine e e runs are based on IPnlllll'IIH::1 a 1.0 pCiJ co centra
- o UREG-1575 nd The data n Attachm 137 and Co-60 so*1 e
,uu.1.111c.:a u
icrosh e runs to exDOS r
va ues on e source to de ecto etry. The al'M::l.ctc, ts 8.3 uttlized MARSSIM guid nee and or n
to the gamma e nuclld
- n r cpm to so pCi/g co ntra Graphi tation of
~*r-b 2.0 compares the d rived MDC results for nt ck.ro of 6,000 cpm for the Attachm nt 8.4, Scan MOC Fonnula and pCi/g De or re ponse to Co-60 (.0 nuclide fraction)
(
tivtty) than for C 137 1.0 nucr e fraction) 60 nuclide fracfon increases the DC *n d
...,..,...a.t FC-19-006 Revision 0 Sof48 8.5
.1
~
0 44-10 Dietedo( s Table 2.0 44-10 Detector Scan MDC (pCl/g,-
for Varied Ca-137 and Co-60 Nuclide Fractions Detector otstance-lnchel (cm) 2.0 (5.08) 3.0 (7.82) e.o (15.24)
Nuclide Fraction c... 13715%
Co-805%
4.36 5.2 7.2
.OOOcpm.
d = ~5 d
Fraction C.-137...
Co-eG1K 4.1 4.8 67
~
tom dillllctor..s-cap ID soll llUl'face QbHClltionl ilmi BtlYDi 4.7
$.7 7.8 Nuclide Fraction Co-60100%
2.5 3.0 4.2 6.5.1 Table 2.0 above presents the evaluation resutts. The resutts show that as the Co-60 nuclide fraction lncreasea the MDC decreases. At other reactor decommisslonfng sites Cs-137 was the dominant radlonudide oth Maine Yankee and Rancho Seco reported an averaged soil Cs-137 content of ii!: 90 percent. An initial nuclide fraction of 0.9 and 0.1 for C.-137 and Co-60 will be used for site charaderization surveys at FCS. Site characterization data will be continually assessed and used to update the soil or structure radionuclide mixture MOC and action levels.
6.6 Saney Techniques 6.8.1 Detector background during land scanning operations is expected to range between 4.00E+03 and 6.00E+03 cpm. Tables 2.0 and 3.0 illustrate the MDCs (In pCi/g) for various distances and scan speeds. Identification of regions of potential contamination is based on the ability of the surveyor to distinguish an increase in count rate durtog the scanning operation. The surveyor Is required to maintain the selected scan speed and detector distance from the suspect surface. Surveyor scanning sensitivity is discussed in chapter 6.0 of NUREG-1575 and NUREG-1507. Other survey techniques that may Improve scan sensitivity include: use of the latching mode parameter of the data logging survey instrument (Ludlum 2350-1) to capture the maximum count rate when scanning a a..,spect surface. changing the instrument (Ludlwn 2350-1) time constant from variable to a fixed 1.0
- cond time constant to incraa8e the instruments response rate and setting the instrument alarm levet. Each of the above features augments the~* efficiency for detecting areas of elevated activity.
L T ble 3.0 L
4.0 7.0 REFERENCES
- 7. 1 t DTBO-05-012 v-0, 11nIos (Evaluation of Km;po1nse Factors Robert F. Decker, 7.2 NUREG-1575, Manu I
(
RSSI r 7.3 NUREG-1757 V2, R 1
Su and D emf na o
- 7.
NUREG-1505. Rev 1, *A nd Analysi o Fin S 8.0 ATTACHMENTS 8.1 Co--60 and Cs-137 Re pon F
Evalua ion of SPA-3 and Ludlu 10 Microshield ' runs for 7.62, 15.24 and 30.
Sourc Certificate for Co-60 S rial Num r 2 17-1 Ev luation of SPA-3 and Ludlum 10 cpm C
7 TM runs for 15.2. 30.48 and 60.9 cm o C 137
,ca for Cs-137 Serial Number LY 376 (SC
- 18)
"""uu:a. F ctors or SPA-3 and
-10 Oet cto 10 D t cto fo C 137
Ludun Model 44-10 Detector 8.2 MicroShield 111 Code Runa for Vanoua Dtetances and Nuclide Fractions FC-19-00 RevtsionO P
7of48 Co-80 nucltde fraction equala 1 0. Dtatance equala 7.62, 10.16 and 15.24 centimeters from detector centtrine.
C.137 nucltde fniction equals 1.0. Oiatance equal& 7.82, 10.16 and 15.24 centimeters from detector 081 lteltine.
Co-eo nucllde fraction equata O 05 and C.137 nuclide fraction equals 0.95. Distance equals 7.82. 10.18 and 15.24 centimeters from detectorcentarllne.
Co-eo nuclide fraction equals 0.10 and C.137 nuclide fraction equals 0.90. Distance equals 7.82. 10 18 and 15.24 centimeters from detector centerttne.
8.3 Scan MOC (pQ/g) for Various Nuclide Fractions of Co-80 and C&-137 Co-<<> nuclde fraction equals 1.0. Distance is as noted in Section 8.2. Scan speed equals 0.5 mis.
C..137 nuclide fraction equals 1.0. Distance is as noted in Section 8.2. Scan speed equals 0.5 mis C.137 nuclide fraction equala 1 0 Distance ts as noted in Section 8.2. Scan speed equals 0.25 m Co-<<> nuclide fractk>n equals 0.05 and C.137 nuclide friction equals 0.95. Distance ts as noted In Section 8.2. Scan epaad equal& 0.5 mis.
Co-60 nuclide friction equals 0.10 and Cs-137 nuclide fraction equala 0.90. Distance Is as noted In Section 8.2. Scan speed equals 0.5 mis.
Co-80 nuclide fraction equals 0.10 and C.-137 mlClide fraction equals 0.90. Distance Is as noted In Section 8.2. Scan spaad equals 0.25 mis.
8.4 Scan MOC Formula and pCi/g Determination Example
D m
7.62 15.24 30.48 A
h t 8.1 C
O nd C 137
- Fae or D rm na o In tru n
Re ul ment
- condu 10 arming 1o-m 3-8525, 10 ~
1
ElllflX
~
0.6938 1 732 13325 M6cro8h&.ld vi.GI (IJII.ONN}
SllcnNMnto Municipal UllllllJ Dlatrlct FC-19-006 Revision o Paptcl48 Fie Ref: ___ _
C..1 Date: ___ _
Au&)uat24 2004 7:-45:23 AM 00'.00 00 tililia Co.<<)
Cue
Title:
Co-tO Oescriptton: Nal R*ponse ChKt O 7.&2 cm Geanwtry. 3
- Disk Radius
- 1 lourMlnput
~
Dimension*
0.238cm DoN Points 1.Jcm O~
3.0 In 00 In Grouping Method t Actual Photon E.......
3~,.~ 2~
Buildup The material,.,.,..,.... : Mr Gap Integration,.....,...rs Radiat 20
~
20 Ruulta
~
F fs.617.01 1 1 3 995e+03 e.419e+OO 1,1478-02 3.9958+03 7 2918+00 1.284e-02 1
0 Jn i
ocm 0.0ln l2tDlk 0.00122 t 'M7e-02 1..265e-02 lOTALS:
7991*+03 1 371e+01 1.371...01 2.411&-02 2.412e-02
11 m
loutvit Dem.n1lona 0.238 cm o 1,11 OONPalntl X
- 1 15.z.1 Oan e.o o.o 1n Soun:e Input
~Method* M11.1t1 Pholon 1...,...
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ca.1 AA.-,.24 2004 7:48:15AM 00:00;00 MlcroShleld v5.05 (5.06-00488}
Sacramento Munfotpaf Ultlllty District CIN TIiie: C~
l>Ncrlptlon: Hal llHponH Check O 30."8 cm Geometry: 3
- Disk Source Dimensions Radius 0.238 cm
- 0. 1 In OoNPotnta
- 1 30.4cm o~
1 ft 0.0 In Shields Shfll4 Name Ma\\trill AwGap Air Source Input Groupklg Method : Actual Photon Energlft 0cm 0.0 lrl p,m;ty 0.00122 ft 1 oP..oo-r 3~.. ~, 2.~
8uUdup The matertal reter.nce Is : AJr Gap lntagndlon Parameten
~
Radial Cin'.:umferendal ata.Jnalw 8.517..01 3 6628-05 3.995e+03 4.006&-01 3.0959+03 4.5S0.01 1.991e+03 a.s&1e-01 Results Flu nc Rt MeV!gn't11u2 With a1.1ildy12 3.871 05
,.G12e-01
.557..01 8.570e-01 20 20 I'
m.Btlu
~2 flMil~!.!'2 7 456 8
168e-04 7.895e-04 1.5Q5e..03
.mBlb!
With But dug 7.474 08
CERTIFICATE OF GAMMA STANDARD SOURCE IIOTOPI PIIOOUCTt I.AIIOMTOtllU 1800 Ho, K~ ll, lknbantr C&!llOfnl*
.,. "3-1000
FC-19-006 Revision 0 Evaluation of Eberline SPA-3 and Ludlum 44-10 cpm per pRA, Response Fac10rs Al,oa,at19.2004 RFD The Nal detectors provided ~ Ebef1ine and Ludlum lndUde cpm per pRIJ response facton for tpecfflc nuctides.
The inA'uctions below are used to evaluate the ftllll~~ of both detectors to Ca-137. The results of the 8Y8klation are tc, co,lftrr11 ~
resuts or moclfy the AIIPOfflle fadon accGdll *.
Calibrated Eberline E-600 and Ludlum 2350-1 Eberine SPA-3 and ludlum '4-10 detectors A.EA C.137 Scuce 68970 - LY 378 TapeMealure Material ID position the source and deledor ~
3 feet abOve the floor Material to recant the results of lasfing (utilize dala logging fealures) and boxes provided in tabte below.
C.137 Source: 344 k8q (9.297.,a) on 10l1I03. Decay COf1'eded
- 337.1 k8q (9.111..0) on 8118104 Micro5tueld111 runs attached for point source at 1524. 30.48 and 60.96 an (e. 12 & 24 inches to centerline of detecb' ache area.
Derived Esllma Factors for SPA-3 and 44--10 Detecto SPA-3 SPA..J 44-10 Est mate Observed 44-10 ed Determination le conductlld in an open... with the deteclDI" and soun::e eteY8ll8d 1.0 mew above the surface Walls and ottw obaructiona should be at least 2 mel8rl form the SOUR:e and delecU1f The objeCttve le to minimize e.-lnO effects.
Each meesuremenl ii conducted In the scalar mode for lhe inStrument and 1he measurement {COUl'C) time IS 10.0 minutes.
Background ii evaluated t,y performing a 10 minute count pnor ID the tests and with the touroe removed from area.
Background cpm value: SPA-3
- 8525, 44-10 = 8661 To determine the reeponM to C.137 the net counts per mirue are divided a,, lhe fA1I p,vvided far._ apectllc diltance
Ludlum Model 44-10 o -t 1
Cate1 lllBl Yl.'i 0.0318 0.0322 0.0364 0.6618 TOTALS; 7,2004 NA
~
phglgrllt1IQ 6.602e+03 t218e+04 4.-433e+03 2.881ile+05 3.102...oe MlcroShleld vi.OS (t.os.oo411) hcramtnto Munlctplll U1tlffty DWrlct C.. TIiie: t.11 UCI C.137 ONc,tptlon: Point Source 1t 15.24 ~
~
- Point
- 1 DoNPom cm 6011 811.. lcla 0cm 0.01n Yd ill lourcelnput
,Gfoupine Method i MIUII Ph01on Energlet
~ e.eL 3~
C 137 0.1108e-008 3.3710e+005 Bulkhtp The matertal la : Air Gap I/
'W!!!! HY1i!Jyg Bi 7, 157e-02 7.206&-02 5.962e-04
.338i-01 1.345e-01 1.0758-03 5..S02e-02
&.MQe-02 a.129e-04 8.496e+01 6.504e+01 12598-01 8 522...01 8.5308+01 1.27v.o1 FC-1 -006 Revision O p
I 14of48 z
0cm 001n Dab 0.00122 rnBlbr Hd 6.003e-04 1.083e-03 S.147e-04 1.291..oi 1.281.01
Ludlum.......,.10 D1l111Dr~
MicroShietd YS.05 (5.05.oo.tl8)
Sacramento....., Ullllr Dfmlct c... Tile: 1.11 UCi C.*1'7
- Point Source at 30.48 c:m Geolnltry. *Polnt 0
an Hl s..-.
FC-19-006 RevisionO Pap11-Gf48 Fie Ref: ___ _
Oaee* ___ _
l Oem 0cm G.O O.Oin
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~ '2loil't 0.00122 0.0318 e.e02e+Ol 00322 1.21a.+o4 (U)384
... ~
o.ee,,
2.88te+05 TOTALI*
S.1029+05 Soutce Input GtoupQag Method~ Aclull Photon EMlpS a?1fm a.e~ a~
C.137 t.1108e-006 3.3710e+005 lulleup The materlaf,.,.rence la : Air Gap Ruutts R9ti:t ElS.O.Q~(" Bili tnBlb!
9e-02 3.323e-02 3.388&-02 2.174&-04 1.36'Je.-02 1.38h-02 7.n..o&
822t+01 1.-..01 S.1~
1.821e+01 US32e+01 193--02 ExQosure Rate tnBlhr With Bu!kiup 1 503 a.111.o4 7.885e-()5 3.151..0Z 3.201..o2
Cffl Rlf ___
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!!9"1fll41 Scan MDC Formul* and pCllg Determination Example The I scan MOC utiliZes the same fom1tdas and approach as that found in NUREG -1507, Section 6.8 2 and NUREG-1575, Section 8.7 for open land areas. The following formula pararneterJ are ~:
Scan speed 0.25 and 0.5 mis Area of lnt8198t:
50 cm diameter (0.198 m2) resufta in a scan width of 0.5 m Soll Depth:
8.0 inches (15.24 cm)
Soll Density; 1.6 wan' Soll Compoefflon:
Sand {SIOz Si
- 46. 74%. 0 53.28%)
Background Count Rate:
6.0E+03 cpm Surveyor Efficiency:
0.5 Detector Response (Co-fJO):
430 q>mfµR/h (See Table 1.0 and Attachment 8.1)
Detector Response (Cs-137):
940 cpm/J&Rlh (See Table 1.0 and Attachment 8.1)
Index of Sensitivity (d'):
1.38 MOCR:
Minimum Detectable Count Rate (cpm)
MicrOShieki µR/h/pCi/g:
For varying distances and radionuclide mix (See Table below)
Detector Distance u
I Nuclide Nuclide Fraction Fraction to end cap C.-137 95% C*13790%
Fraction Fraction lnches (cm)
Cc>60 %
Cc,.600% C*137100% co-eo 100-w.
2.0 (5.08) 0.3033 0.3437 0.2628 1.0720 3.0 (7.62) 0.2544 0.2883 0.2206 0.8975 4.0 (10.18) 0.2156 0.2442 0.1869 0.7593 5.0(12.7) 0.1843 0.2087 0.1598 0.6486 To determine the MDC the MOCR muet be calculated by find determining the rmnlmum detectable number of net source counts In the interval as given by a.
,, - d!,tr, The value of d' is selected from Table 8.5 of NUREG-1575 based on the required true positive and fal8e positive rates and b, ls the number of background counts In the Interval For a background count rate of 8.0E+o3 cpm and a scan area of interest 50 cm diameter, a acan rate of 0.5 mis (reaullilg Jn a detector residence timed 1 aecond) then s, (MDCR) Is 8.28E+02 cpm as detenmned below:
.00£ 03 MDCR I dju t u I,
Th 7.7 10 OC ( n
- ctor, pro
- ed 1n this nd Ion f ctors fo oe d tance of 5 ve dertv d
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