ML081610168
| ML081610168 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/08/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-032 | |
| Download: ML081610168 (28) | |
Text
Rancho Seco Final Status Survey Summary Report April 8, 2008 Misc. Waste Filter Room, (Room 026)
Survey Unit F8130351 Prepared By:_
FSS eer Reviewed By:
Lead I{S ngineer Approved By:
Date:4 oo Date:
Date:
Radiological I
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130351, Misc. Waste Filter Room, (Room 026)
Survey Unit
Description:
Operating History: The Misc. Waste Filter Room is located on the -20' elevation of the Auxiliary Building. The Auxiliary Building is a reinforced concrete structure that, during power operations, contained the Radwaste processing and supporting systems. The building has six main elevations. Residual levels of surface radioactivity were detected on all interior elevations of the building. Operating records and the HSA document several events with the potential for a release of radioactivity inside this structure.
Site Characterization: Direct measurements were taken on each interior elevation of the Auxiliary Building. These measurements confirmed the presence of plant-derived radionuclides. Direct measurements taken on the -20' elevation, showed a mean gross activity level of 247,831 dpm/100 cm2 and a maximum value of 10,080,000 dpm/100 cm'.
Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior surfaces of the Auxiliary Building were determined primarily to be a Class I for the floors and lower walls (bottom 2 meters of the walls), and Class 2 for the upper walls and ceiling. Inside the Misc. Waste Filter Room there were a number of areas on the floor, lower walls, and upper walls where the~gross surface activity levels were higher than the DCGL prior to remediation. Therefore, a Class 1 final statussurvey was performed on the floor, wall, and ceiling surfaces of the room.
HSA Events: HSA Report pg. 63.
Survey Unit Design Information:
The Survey Unit Design Parameters are presented in Table 1 below. The survey unit and measurement locations are depicted on the maps in Attachment 1. Direct measurement locations were determined using a random-start, fixed grid pattern and 182 m2 were scanned for 100% coverage. Gamma scans were performed on the floor due to the rough surface left from heavy remediation. Beta scans were performed on the walls and ceiling.
Samples of removable contamination were collected at each direct measurement location.
The instrumentation used for the survey along with the MDC values are listed in Tables 2-1 and 2-2 in Attachment 2.
Page 2 of 10 FSS Summary Report F8130351
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:
F813 Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL (dpm/100 cm 2):
Area Factor:
Design DCGLemc (dpm/100 cm2):
LBGR (dpm/100 cni2):
Design Sigma (dpm/100 cm2):
Type I Error:
Type II Error:
Predominant Nuclide:
Sample Area (m2):
Scan Area (Mi 2 ):
Scan Coverage (%):
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacina L:
0351 1
182 Michael Stein 16100 6.15 99015 8050 12035 0.05 0.05 Co-60 2.8 182 100%
1.645 1.645 0.725747 0.6 0.6 54 65 65 1.7 Misc. Waste Filter Room, (Room 026)
Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class 1 Default = 50% DCGL Class 1 Class I Uses 3.0 if Relative Shift is
>3 NUREG-1575 Table 5-5 Class I Class 1 Page 3 of 10 FSS Summary Report
.F8130351
Survey Results:
A total of 65 direct measurements were made' in F8130351. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. Five of the scan measurements indicated areas of elevated activity as indicated in Attachment 3. Beta scan measurements of the walls and ceiling resulted in activity range from 4,705 to 545,332 dpm/100 cm 2, based on a surveyor efficiency of 0.5 and no background subtracted. Gamma scan measurements of the floor resulted in activity range from 2,172 to 2,693 dpm/100 cm 2 Co-60 and from 2,434 to 20,321 dpm/100 cm 2 Cs-137. Samples for removable surface activity were all less than 10% of the DCGL as shown in Table 3. Removable surface activity samples were counted for alpha activity and none was detected at the MDC shown in Table 2-1 of.
Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm F8130351-CO001BD 2051 F8130351-CO002BD 2559 F8130351-CO003BD 2324 F8130351-CO004BD 2102 F8130351-COOO5BD 3968 F8130351 -CO006BD 2140 F8130351-CO007BD 2070 F8130351-CO008BD 2267 F8130351-CO009BD 2133 F8130351-COOIOBD 1917 F8130351-CO011BD 1848 F8130351-CO012BD 1816 F8130351-Co013BD 2273 F8130351-Co014BD 2292 F8130351-CO015BD 2425 F8130351-CO016BD 2025 F8130351-CO017BD 4559 F8130351-CO018BD 2095 F8130351-CO019BD 2197 F8130351-CO02OBD 2108 F8130351-CO021BD 2387 F8130351-CO022BD 2140 F8130351-CO023BD 2083 F8130351-CO024BD 3365 F8130351-CO025BD 5810 F8130351-CO026BD 2692 F8130351-CO027BD 2070 F8130351-CO028BD 2146 F8130351-CO029BD 2260 F8130351-CO03OBD 2317 F8130351-CO031BD 1981 F8130351-CO032BD 2229 Page 4 of 10 FSS Summary Report F8130351
FBI 30351 -COO33BD 2559 F8130351 -CO033BD F8130351 -CO034BD F8130351 -CO035BD F8130351-CO036BD F8130351 -CO037BD F8130351,-CO038BD F8130351-CO039BD F8130351-CO040BD F8130351-CO041BD F8130351-C0042BD F8130351-CO043BD F8130351-CO044BD F8130351-CO045BD F8130351-CO046BD F8130351-CO047BD F8130351 -CO048BD F8130351 -CO049BD F8130351 -CO05OBD F8130351 -CO051 BD F8130351 -CO052BD F8130351 -CO053BD F8130351-CO054BD F8130351-CO055BD F8130351-C0056BD F8130351-C0057BD F8130351-CO058BD F8130351-C0059BD F8130351-CO06OBD F8130351-CO061BD F8130351-CO062BD F8130351 -CO063BD
.F8130351 -CO064BD F8130351 -CO065BD Mean:
Median:
Standard Deviation:
Ranqe:
2559 1822 2787 2076 1314 2108 2324 1975 1676 1924 1949 1962 2317 2305 2013 1486 2387 1810 2298 2571 2165 2457 2400 1359
.2387 2982 3404 2196 2676 2793 2604 6284 3404 2422 2229 844 1314 - 6284 Ranqe:
1314 -6284 Page 5 of 10.
FSS Summary Report.
F8130351
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8130351 C0001 SM 24.09 F8130351C0002SM 24.09 F8130351 C0003SM 13.83 F8130351 C0004SM 1.01 F8130351 C0005SM 402.24 F8130351 C0006SM 9.98 F8130351C0007SM 2.29 F8130351C0008SM 1.01 F8130351C0009SM 8.7 F8130351C0010SM
-1.55 F8130351C0011SM 1.01 F8130351C0012SM 2.29 F8130351C0013SM 25.37 F8130351C0014SM 2.29 F8130351C0015SM 26.65 F8130351C0016SM 2.29 F8130351C0017SM 130.48 F8130351C0018SM 1.01 F8130351C0019SM 2.29 F8130351C0020SM 1.01 F813035' C0021SM 8.7 F8130351 C0022SM 4.86 F8130351C0023SM 1.01 F8130351 C0024SM 3.58 F8130351 C0025SM 134.33 F8130351C0026SM 6.14 F8130351C0027SM
-0.27 F8130351C0028SM 7.42 F8130351C0029SM 6.14 F8130351 C0030SM 3.58 F8130351C0031SM 12.55 F8130351 C0032SM 3.58 F8130351C0033SM 1.01 F8130351C0034SM 2.29 F8130351C0035SM 16.39 F8130351 C0036SM 2.29 F8130351C0037SM 1.01 F8130351C0038SM 6.14 F8130351C0039SM
-0.27 F8130351C0040SM 7.42 F8130351CO041SM
-1.55 F8130351C0042SM 7.42 F8130351C0043SM 1.01 F8130351C0044SM 2.29 F8130351C0045SM 39.47 F8130351C0046SM 6.14 F8130351 C0047SM 15.11 F8130351 C0048SM
-1.55 Page 6 of 10 FSS Summary Report F8130351
F8130351 C0049SM F8130351 COO5OSM F8130351 C0051 SM F8130351 C0052SM F8130351 C0053SM F8130351 C0054SM F8130351 C0055SM F8130351 C0056SM F8130351 C0057SM F8130351 C0058SM F8130351 C0059SM F8130351 C0060SM F8130351C0061SM F8130351C0062SM F8130351 C0063SM F8130351 C0064SM F8130351 C0065SM Mean:
Median:
Standard Deviation:
Range:
3.58 25.37 2.29 3.58 9.98 2.29 36.9 17.68 13.83
-0,27
-0.27 1.01 1.01
-0.27 1.01
-0.27
-0.27 16.83 3.58 54.01
-1.55 to 402.24 Page 7 of 10 FSS Summary Report F8130351
Survey Unit Data Assessment:
The survey design required 65 direct measurements for the Sign Test. The critical value and the results of the Sign. Test are presented in Table 4. The sample mean and median values were less than the DCGL. The sample standard deviation was less than the design standard deviation so no additional samples were required.
Page 8 of 10 FSS Summary Report F8130351
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm 2):
N/A Ambient Background Used (dpm/100 cm 2):
N/A Average Ambient BKG = 0 Actual Direct Measurements (N):
65 Median (dpm/rrO0 cm 2):
2229 Mean (dpm/100 cm 2):
2422 Direct Measurement Standard Deviation 844 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm2):
844 Based on samples and backgrounds.
Maximum (dpm/100 cm 2):
6284 Material Type:
N/A Background Subtract Not Applied Sign Test Final N Value:
65 S+ Value:
65 Critical Value:
39 Sufficient Samples Collected:
Yes Maximum Value < DCGL:
Yes Median Value < DCGL:
Yes Mean Value < DCGL:
Yes Maximum Value < DCGLemc:
Yes Class 1 Total Standard Deviation <= Sigma:
Yes Pass the Sign Test?
Yes Reject the Null Hypothesis?
Yes Does the Survey Unit Pass All Criteria?
Yes Page 9 of 10 FSS Summary Report F8130351
Survey Unit Investigations and Results:
An investigation was required for the five scan measurements as indicated in Attachment
- 3. Investigation of the areas resulted in the decision to perform additional remediation.
The investigation results in Attachment 3 represent the residual radioactivity levels achieved after additional remediation.
ALARA Statement:
As stated in Chapter 4 of the LTP, as long as the residual activity within the survey unit is less than the DCGL (i.e. the survey unit average activity is less than the DCGL and the EMC criterion has been met), the ALARA criterion has been met.
Changes in Initial Survey Unit Assumptions:
The survey unit was designed as a Class 1 structure survey and the sample results are consistent with that classification. The variability of the survey results was less than the characterization data used for survey design. Five potential areas of elevated activity were detected as indicated in Attachment 3.
==
Conclusion:==
The FSS of this survey unit was properly designed as a Class I survey based on Table 5-4 of the LTP. The required number of direct measurements was made and the scan coverage met the requirement of Table 5-6 of the LTP. No direct measurements exceeded the DCGL of 16,100 dpm/100 cm 2 and none of the removable surface activity measurements exceeded 10% of the DCGL.
The direct measurement data support rejection of the null hypothesis, providing high confidence that the survey unit satisfied the release criteria and that the data quality objectives were met.
It is concluded that survey unit F8130351 meets the release criteria of 10CFR20.1402.
Page 10 of 10 FSS Summary Report F8130351 Maps April 8, 2008 Survey Unit F8130351
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1 2
3 SCALE METERS Instrumentation April 8, 2008 Survey Unit F8130351
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.
Model; Serial No.
(dpm/100 cm 2)
(dpm/100 cm2 )
M2350; 142507 43-68B; 160781 530 1263 M2350; 142507 43-116-1B; 256008 1000 4092 M2350; 175834 43-116-1B; 190642 1000 4092 M2350; 180733 43-98B; 148638 2540 4580 M2350; 142515 43-111B; 148642 1700 3070 ISOCS 1983947 N/A 1550 Cs-137 1590 Co-60 Tennelec; 0401171 N/A 5.15 dpm a, N/A 8.12 dpmr P Table 2-2. Investigation Criteria and DCGL
- Parameter Value (dpm/100 cm2)
Investigation Criteria - Direct 99015 Investigation Criteria - Scan
-99015, DCGLw 16100 DCGLEMc 99015 Page 2 of 2 Att. 2 Instrumentation F8130351 Investigation April 8, 2008 Survey Unit F8130351
Table 3-1 Survey Unit Investigation Investigation Initial Value Investigation Elevated Area Investigation DCGLemc Grd Lvl(p)
(P)Result Ara(2 atr D CGLernc Result Unity eel(p)(cpm)
(dpm/l 00cm2)
Fraction C0002BS 3,650 14,220 890 0.0055 2187 35,210,700 24,089 0.00 C0006BS 3,650 20,148 412 N/A N/A N/A 11,151 0.00 C0007BS 3,650 5,587 389 N/A N/A N/A 10,529 0.00.
C-0093BS 3,650 7,074 2,655 0.0126 952 15,327,200 71,861 0.00 C0008JS 7,178 8,679
- 565, N/A N/A N/A 7,767 0.00 Survey Unit Remainder DCGL=
SUMean=
0.15 16,100 2,422 EMC Unity Sum 0.15 All of the grids above were initially greater than DCGLemc. Investigation of the areas resulted in the decision to perform additional remediation. The investigation results above represent the residual radioactivity levels after additional remediation.
Page 2 of 2 Att. 3 Investigation-F8130351 Data Assessment April 8, 2008 Survey Unit F8130351
F8130351 Gross Activity Sample Results Quantile Plot 0)o DCGL 16100 dpm/100cm2 7,000 7-6,000
+..
2 4,000 I-114-
, I 2 2 2 9 2,000
-~ ~ -
2,000 0
20 40 60 80 100 Percentile Direct Measurements (dprn/100cm2) nmedian 75th Percentile - - - - 50th Percentile
00 w
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~r1 00 F8130351 Gross Activity Sample Results Scatter Plot DCGL = 18100 dpml100cm" 7000 oE
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6000-5000 4000-3000 -
2000-1000-0 0
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Gross Activity -
Average -
"+3StDev" -
"-3StDev"
0 F8130351 Gross Activity Frequency Plot DCGL = 16100 dpm/1 00cm2 Q1)
C0 30 28 26 24 22 20 18 16 14 12 10 8
6 4
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Bins - Upper End Value (dpm/100cm2)