ML090850551
| ML090850551 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/21/2008 |
| From: | Frank G Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML090850551 (20) | |
Text
Rancho Seco Final Status Survey Summary Report July 21, 2008 North Central Floor, Grade Level Survey Unit F8260171 Prepared By: __
- L 1
Date: -2Z'2 FSS Engineer Reviewed By:ý Oý Date:
19 Lead FSS Engineer Approved By:
Z_;7 Date: ?-Z 7 Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8260171, North Central Floor, Grade Level Survey Area Classification Area ID #: 826000 Survey Area: Turbine Building Operating History: The reinforced concrete and steel structure contained the turbine-generator and supporting systems. The building contained five 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.
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 in the condenser pit elevation showed a mean gross activity level of 3077 dpm/100 cm2 and a maximum value 2
of 24,900 dpm/100 cm. Direct measurements on the grade elevation showed a mean gross activity level of 2,035 dpm/100 cm 2 and a maximum value of 6,980 dpm/100 cm2 Direct measurements on the mezzanine elevation showed a mean gross activity level of 1,566 dpm/100 cm 2 and a maximum value of 2,626 dpm/100 cm 2. Direct measurements on the +40' elevation showed a mean Rross activity level of 2,843 dpm/100 cm2 and a maximum value of 3,615 dpm/100 cml. Direct measurements on the building exterior showed a mean gross activity level of 1,984 dpm/100 cm 2 and a maximum value of 10,312 dpm/100 cm 2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior of the turbine building was determined to be Class 1, 2, & 3 areas and the exterior was a Class 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 16.6 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 8 FSS Summary Report F8260171
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:
F826 Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL (dpm/100 cm'):
Area Factor:
Design DCGLemc (dpm/100 cm 2):
LBGR (dpm/100 cm 2):
Design Sigma (dpm/100 cm 2):
Type I Error:
Type II Error:
Predominant Nuclide:
Sample Area (m2):
Scan Area (Mi2):
Scan Coverage (%):
z1 -p Sign P:
Calculated Relative Shift:
Relative Shift Used:
0171 1
16.6 Gary Frank 43000 13.1 563522 21500 3130 0.05 0.05 Cs-137 1.18 16.6 100%
1.645 1.645 0.99865 6.9 3
North Central Floor, Grade Level Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class 1 Default = 50% DCGL Class 1 Class 1 Uses 3.0 if Relative Shift is
>3 NUREG-1575 Table 5-5 Class 1 Class 1 N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
11 14 14 1.0 Page 3 of 8 FSS Summary Report F8260171
Survey Results:
A total of 14 direct measurements were made in F8260171. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. None of the scan measurements indicated areas of elevated activity. Scan activity ranged from 5524 to 13036 dpm/100 cm2, 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 Attachment 2.
Table 2. Direct Measurement Results Measurement ID Gross Activit (dpm/100 cm F8260171-CO001BD F8260171 -CO002BD F8260171-CO003BD F8260171-CO004BD F8260171-CO005BD F8260171 -CO006BD F8260171-CO007BD F8260171-CO008BD F8260171-CO009BD F8260171-COOlOBD F8260171-CO011BD F8260171-CO012BD F8260171-CO013BD F8260171-CO014BD Mean:
Median:
Standard Deviation:
Range:
2215 2028 2002 2656 2070 4243 4015 2801 5203 2298 1940 1893 1992 2049 2672 2142 1047 1893-5203 Page 4 of 8 FSS Summary Report F8260171
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpmll00 cm 2)
F8260171 C0001SM F8260171 C0002SM F8260171 C0003SM F8260171 C0004SM F8260171 C0005SM F8260171CO006SM F8260171C0007SM F8260171 C0008SM F8260171 C0009SM F8260171Co010SM F8260171C0011SM F8260171C0012SM F8260171C0013SM F8260171CO014SM Mean:
Median:
Standard Deviation:
Range:
-2.24 0.34
-3.53 2.93
-3.53
-4.82 0.34
-3.53 0.34
-0.95
-3.53
-0.95
-3.53
-2.24
-1.78
-2.24 2.19
-4.82 to 2.93 Page 5 of 8 FSS Summary Report F8260171
Survey Unit Data Assessment:
The survey design required 14 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 6 of 8 FSS Summary Report F8260171
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):
14 Median (dpm/100 cm2):
2142 Mean (dpm/100 cm2):
2672.
Direct Measurement Standard Deviation 1047 (dpm/100 cm2):
Total Standard Deviation (dpm/100 cm 2):
1047 Based on samples and backgrounds.
Maximum (dpm/100 cm2):
5203 Material Type:
N/A Background Subtract Not Applied Sign Test Final N Value:
14 S+ Value:
.14 Critical Value:
10 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 7 of 8 FSS Summary Report F8260171
Survey Unit Investigations and Results:
No investigations were required for either direct or scan measurements and no investigation results are reported.
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.. No potential areas of elevated activity were detected. 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 cm 2 and none of the removable surface activity measurements exceeded 10% of the DCGL. No investigations were required.
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 F8260171 meets the release criteria of I0CFR20.1402.
Page 8 of 8 FSS Summary Report F8260171 Maps July 21, 2008 Survey Unit F8260171
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I jI 1 E1 00-i.4 Location of Turbine Building inside the Industrial Area i**
.T..............Nt1" 00 0'~Map F8260171 -1, Turbine Building North Central Floor Area 2
A Laocation of Turbine Building at Rancho Seco site
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91'A" 170N" 20'4" 18' 4" 18' 135" 1A'10 i"
18'4" 23'4" 23'4" 23' 4" 16' 11" -
17, (1" 20'4" 2
3 4,
8 910 ti 12 13 00 c:)
Map F8260171-2, Turbine Building Grade and Below Elevations Location of North Central Floor Class 1 Survey Unit
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OP North Central Floor Area - Class 1 Beta Direct/Smears 2.0-1.5-1.0-0.5-02 1m 04 1m 06 im 08 im 10 im 12 1m 14 1m 1M 1m 1M 1M 1m 1m 01 1M 03 I
lii II11111111111 05 1m 07 1m 09 im 11 im 13 11111.1111111 I~I 111111111111111111111111 I I x
/
I I II1\\1 I I I I VI I I I I I I I I I I
.v 0
1.5 2.0 1.4m 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Measurement in meters I I I I I I I I1 1 6.5 7.0
= Random Start - See Random Trials Sheet All Beta Direct/Smear locations are measured from random start point It00 I'
F8260171-M3
0 North Central Floor - Class 1 Beta Scans 2.0-1.5-1.0-0.5-ci)
I I I I I I I I I
I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Ii I I I I I I II11 1 1 1I II I 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 Measurement in meters ITI 00
---3 F8260171-M4 Instrumentation July 21, 2008 Survey Unit F8260171
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.
Model; Serial No.
(dpm/100 cm2)
(dpm/100 cm 2 )
M2350; 203481 43-68B; 161405 433 1033 Tennelec; 0401171 N/A 6 dpm a, 12 dpm f3 N/A Table 2-2. Investigation Criteria and DCGL Value Param eter V l eC 2
(dpm/100 cm 2)
Investigation Criteria - Direct 43000 Investigation Criteria - Scan 43000 DCGLw 43000 DCGLEMC 593522 Page 2 of 2 Att. 2 Instrumentation F8260171 Investigation July 21, 2008 Survey Unit F8260171 (none required)
Data Assessment July 21, 2008 Survey Unit F8260171
00 F8260171 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm2 I
4-6,000 5,000 4,000 3,000 2,000 2142 1,000 -
0 0
20 40 60 80 100 Percentile Direct Measurements (dpr/lO0cr2) median 75th Percentile
- 50th Percentile
i-v tJQa a) 0 A
F8260171 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmllo0cm=
A cna 00 k)
ON O0
-. 4
-4 7000 r-6000 E8 5000 C
4000 Ea. 3000
- 0 2000 1000 0
-1000 w
- 1 5814 0
0 0
0 0
0 0
0 0
a-i 2572
-470 o
a a
a a
a a
a 0
a a
a a
a 0
C 0
a a
a a
a a
0 a
0 a
o 00 000 U
U 0 U0 0
0 0
0 0
Measurement Locations o
Gross Activity -
Average - -
"+3StDev
"-3StDevj
0 00 CN F8260.171 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2 11 10 0-O0 9
8 7
6 5
4 3
2 1
0 8
Bins - Upper End Value (dpm/100cm2)