ML090980388
| ML090980388 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/26/2008 |
| From: | Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML090980388 (37) | |
Text
k' Rancho Seco Final Status Survey Summary Report Revision 1 May 1, 2008 Room 39 Lower Walls and Floor Survey Unit F8130521 Prepared By:
Date:_______
FSS Engineer Reviewed By:
Date: (
Log Lead FSS Engineer Approved By:
2Z J"
Date:-?
7 Dismantlement Superintendent, Radiologica.l
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130521, Room 39 Lower Walls and Floor Survey Unit
Description:
Operating History: The reinforced concrete structure contained the RadWaste processing and supporting systems. The building contained six main elevations. Residual radioactive material was known to be present on all levels of the interior of the building.
Operating records and the HSA document several events with the potential for a release of radioactivity inside this structure. One report documented contamination of the auxiliary building roof. The roof was later replaced.
Site Characterization: Direct measurements were made of each of the interior elevation surfaces as well as the exterior surfaces of the structure. These measurements confirmed the presence of plant-derived radionuclides. Direct measurements on the -47' elevation showed a mean gross activity level of 320,071 dpm/100 cm 2 and a maximum value of 5,720,000 dpm/100 cm 2. Direct measurements on the -29' elevation showed a mean gross activity level of 544,756 dpm/100 cm2 and a maximum value of 11,370,000 dpm/100 cm 2. Direct measurements on the -20' elevation showed a mean gross activity level of 247,831 dpm/100 cm 2 and a maximum value of 10,080,000 dpm/l00 cm 2. Direct measurements on the grade elevation showed a mean gross activity level of 373,758 dpm/100 cm 2 and a maximum value of 5,800,000 dpm/100 cm2. Direct measurements on the +20' elevation showed a mean gross activity level of 85,408 dpm/l100 cm 2 and a maximum value of 1,900,000 dpm/l100 cm 2. Direct measurements on the +40' elevation showed a mean gross activity level of 3,288 dpm/100 cm 2 and a maximum value of 24,781 dpm/100 cm2. Direct measurements, on the building exterior, including the mezzanine roof, showed a mean gross activity level of 1,897 dpm/l100 cm 2 and a maximum value of 2,990 dpm/100 cm 2. (The roof had been replaced prior to the classification survey.) Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior of the auxiliary building was determined to be a Class 1, 2 area and the exterior was a Class 2,3.
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 236 m2 were scanned for 100% coverage. 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 9 FSS Summary Report F8130521
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:
F813 Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL (dpm/100 cm2):
Area Factor:
Design DCGLemc (dpm/100 cm 2):
LBGR (dpm/100 cm 2):
Design Sigma (dpm/100 cm2):
Type I Error:
Type II Error:
Predominant Nuclide:
0521 1
236 Gary Frank 43000 3.3 141900 21500 10204 0.05 0.05 Cs-137 6.94 236 100%
1.645 1.645 0.97725 2.1 2.1 Room 39 Lower Walls and Floor Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class 1 Default = 50% DCGL Co-60 used for Area Factor and emc Class 1 Class 1 Uses 3.0 if Relative Shift is
>3 NUREG-1575 Table 5-5 Class 1 Class, 1 Sample Area (m2):
Scan Area (m2):
Scan Coverage (%):
Zl-" :
ZI-0 :
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
12 15 34 2.6 Page 3 of 9 FSS Summary Report F8130521
Survey Results:
A total of 41 direct measurements were made in F8130521. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. Two measurements indicated elevated activity above the investigation level resulting in an investigation documented in Attachment 3. Scan activity ranged from 2978 to 44872 dpmr/100 cm 2, based on a surveyor efficiency of 0.5 and no background subtracted. 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 F8130521-COOOIBD 2734 F8130521-CO002BD 2241 F8130521-CO003BD 2142 F8130521-CO004BD 2573 F8130521-CO005BD 2946 F8130521-CO006BD 2407 F8130521-CO007BD 2718 F8130521-CO008BD 2417 F8130521-CO009BD 2495 F8130521-COOIOBD 2485 F8130521-Co011 BD 2900 F8130521-CO012BD 2682 F8130521-CO013BD 3377 F8130521-CO014BD 2692 F8130521-CO015BD 2485 F8130521-CO016BD 2874 F8130521-CO017BD 2848 F8130521-CO018BD 2568 F8130521-COO19BD 4254 F8130521 -CO02OBD 19271 F8130521-CO021BD 8735 F8130521-CO022BD 5073 F8130521-CO023BD 3870 F8130521-CO024BD 2967 F8130521-CO025BD 8014 F8130521-CO026BD 4228 F8130521-CO027BD 2459 F8130521-CO028BD 3901 F8130521-CO029BD 4456 F8130521-CO03OBD 2609 F8130521-CO031BD 2728 F8130521-CO032BD 2749 F8130521-CO033BD 2900 F8130521-CO034BD 5882 F8130521 -CO035BD 9109 Page 4 of 9 FSS SummaryReport F8130521
Measurement ID Gross Activity (dpmll00 cm)
F8130521-CO036BD 2371 F8130521-CO037BD 1956 F8130521-CO038BD 2552 F8130521-CO039BD 2485 F8130521-CO04OBD 2848 F8130521-CO041BD 2594 Mean:
3795 Median:
2734 Standard Deviation:
3000 Range:
1956-19271 Page 5 of 9 FSS Summary Report F8130521
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm2)
F8130521 C0001 SM F8130521 C0002SM F8130521 C0003SM F8130521 C0004SM F8130521 COOO5SM F8130521CO006SM F8130521 C0007SM F8130521CO008SM F8130521 C0009SM F8130521Co010SM F8130521Co011SM F8130521CO012SM F8130521CO013SM F8130521CO014SM F8130521CO015SM F8130521CO016SM F8130521CO017SM F8130521CO018SM F8130521CO019SM F8130521 C0020SM F8130521C0021SM F8130521C0022SM F8130521C0023SM F8130521 C0024SM F8130521 C0025SM F8130521 C0026SM F8130521C0027SM F8130521 C0028SM F8130521CO029SM F8130521 C0030SM F8130521C0031SM F8130521 C0032SM F8130521 C0033SM F8130521 C0034SM F8130521 C0035SM F8130521 C0036SM F8130521CO037SM F81 30521 C0038SM F8130521 C0039SM F8130521 C0040SM F8130521 C0041 SM Mean:
Median:
Standard Deviation:
Range:
25.37 39.47 13.83 25.37 30.49 8.7 30.49 30.49 24.09 49.72 18.96 9.98 42.03 27.93 7.42 30.49 22.8 22.8 13.83 57.41 29.21 9.98 3.58
.1.01 1.01 6.14 39.47 8.7 39.47 11.27 1.01 3.58 44.6 8.7 8.7 4.86 1.01
-0.27 4.86 3.58 4.86 18.71 13.83 15.56
-0.27 to 57.41 Page 6 of 9 FSS Summary Report F8130521
Survey Unit Data Assessment:
The survey design required 41 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 7 of 9 FSS Summary Report F8130521
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/]00 cm 2):
N/A Ambient Background Used (dpm/100 cm2):
N/A Average Ambient BKG = 0 Actual Direct Measurements (N):
41 Median (dpm/JO0 cm2):
2734 Mean (dpm/100 cm 2):
3795 Direct Measurement Standard Deviation 3000 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm 2):
3000 Based on samples and backgrounds.
Maximum (dpm/100 cm 2):
19271 Material Type:
N/A Background Subtract Not Applied Sign Test Final N Value:
41 S+ Value:
41 Critical Value:
26 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 8 of 9 FSS SummaryEReport F8130521
Survey Unit Investigations and Results:
Ten investigations (CO002BS, C0004BS and Particle Scans in floor grids 3, 11, 13, 89, 91, 92, 93, and 96) were required for the scan measurements and the results are reported in Attachment 3. The EMC unity rule was not exceeded as shown in Table 3-1.
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 I 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. Potential areas of elevated activity were detected and evaluated as shown in Attachment 3. Therefore the EMC criterion was met.
==
Conclusion:==
The FSS of this survey unit was properly designed as a Class 1 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 43000 dpm/100 cm2 and none of the removable surface activity measurements exceeded 10% of the DCGL. Investigation results while exceeding the DCGL are less than 20% DCGLemc and pass unity.
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 F8130521 meets the release criteria of 10CFR20.1402.
Page 9 of 9 FSS Summary Report F8130521 Revision 1 Maps May 1, 2008 Survey Unit F8130521
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Grids 86, 87 and 88 do not exist and DEC-041 is corrected.
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Page 9 of 118 Att. 1 Maps F8130521
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Grids 86, 87 and 88 do not exist and DEC-041 is corrected.
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ROOM 39 Floor Beta Scans MAP F8130521 - M17
-20' Revision I Instrumentation May 1, 2008 Survey Unit F8130521
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.
Model; Serial No.
(dpm/lO0 cm 2)
(dpm/lO0 cm 2)
M2350; 180733 43-98B; 1486385 590 1070 M2350, 180733 43-98B, 1486386 350 630 M2350; 193700 43-68B; 1902941 433 1033 M2350; 142499 43-37; 1485022 198 616 M2350; 149794 43-116-1 B; 2560053 491 739 M2350; 193700 43-116-1 B; 2160714 796 5895 M2350, 193700 44-10, 256101 N/A 5.2pCi/g Tennelec; 0401171 N/A 5dpm a, 11 dpm N/A
'43-68B Surface Concrete 243-37B Surface Concrete 343-116-1B Juncture Concrete 443-116-1B Surface Concrete 543-98B 2" Concrete 643-98B 2" Metal Table 2.1, Survey Unit Instrumentation Detector MDC Instrument Serial No.
(dpm/1OOcm 2 )
1010 Cs-137 ISOCS 1983920 1320 CO-60 1320 CO-60 56100 Cs-1 37 InSpector 1000*
10054579 22000 Co-60 Page 2 of 3 Att. 2 Instrumentation F8130521
Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/lOO cm2)
Investigation Criteria - Direct 141900 Investigation Criteria - Scan 141900 DCGLw 43000 DCGLEMC 141900 Value (dlm/100cm2)
Instrument Parameter To detect a 100 cm hot spot at the EMC criterion within the detector field of view Concrete ISOCS Investigation Criteria C
snir 37
- Scan 190,000 Cs-137 Scan64,000 Co-60
- See Table 3-1 Page 3 of 3 Att. 2 Instrumentation F8130521 Revision I Investigation May 1, 2008 Survey Unit F8130521
Table 3-1 Survey Unit Investigation 1nResulgtio Unitym Grid/Location Investigation Initial Value IResut Elevated Area DInvestigation DCGLemc Level (cpm)
(cpm) s(cpm) Area (m2)
Factor (d/OOcm2)
Fraction C0002BS 14200 17418 2006 1
14.6 640700 14718 0.0000 C0004BS 14200 17211 2446 1
14.6 640700 17946 0.0000
- (1) Grid 92 36000 42190 N/A
.01 1290 5.56e7 1.00e6 0.0179
- (2) Grid 923 60 29
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- (2) Grid 93 36000 35305 N/A
.01 1290 5.56e7 1.02e6 0.0183 Juncture
- (3) Grid 91 36000 36959 N/A
.01 1290 5.56e7 1.37e5 0.0024
- (4) Grid 11 36000 40072 N/A
.01 1290 5.56e7 9.06e5 0.0162
- (5) Grid 89 36000 53862 N/A
.01 1290 5.56e7 2.23e5 0.0039
.......Juncture..
- (6) Grid 3 36000 36136 N/A
.01 1290 5.56e7 1.20e6 0.0215
- (7) Grid 13 36000 38342 N/A
.01 1290 5.56e7 8.52e5 0.0153
- (8) Grid 96 36000 39382 N/A
.01 1290 5.56e7 1.28e5 0.0022 DCGL =
SU Mean =
0.0883 Survey Unit Remainder
-43,000 3795 EMC Unity Sum 0.1860 Scans were performed with 2350-1 w/43-37B and the investigation level was determined using 100 cm 2 versus the actual area of the probe of 584 cm2.
The investigation was performed using a 43-68B with an investigation level of 19,200 cpm for C0002BS and C0004BS.
Page 2 of 3 Att. 3 Investigation
Gamma scans were performed to complete the particle survey and eight elevated areas were identified. The identified areas were further bounded and analyzed with InSpector 1000.
- Locations on map attached to Download 08-228 The results are shown in Table 3-1 with results less than unity.
Page 3 of 3 Att. 3 Investigation Revision I Data Assessment May 1, 2008 Survey Unit F8130521
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F8130521 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/100cm 2 25,000 -
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0 20 40 60 80 100 Percentile Direct Measurements (dprn/100cnn2' --
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