ML082620076
| ML082620076 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/20/2008 |
| From: | Donna Anderson Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-064 | |
| Download: ML082620076 (22) | |
Text
Rancho Seco Final Status Survey Summary Report March 20, 2008 South Turbine Deck (+) 40' El.
Survey Unit F8260305 Prepared By:
2
- b.
g Date: __________
FSS gieer Reviewed By:
Date:
Le d FSS Engineer Approved By:
[7Date:
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8260305, South Turbine Deck (+) 40' El.
Survey Unit
Description:
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 3,077 dpm/l100 cm2 and a maximum value of 24,900 dpm/100 cm 2. 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/l100 cm 2. Direct measurements on the mezzanine elevation showed a mean gross activity level of 1,566 dpm/100 cm2 and a maximum value of 2,626 dpm/100 cm 2. Direct measurements on the +40' elevation showed a mean gross activity level of 2,843 dpm/100 cm 2 and a maximum value of 3,615 dpm/100 cm 2. 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 233 m2 were scanned for approximately 28% 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 F8260305
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:
F826 Survey Unit:
Class:
SU Area (m2):
Evaluator:
DCGL (dpm/lO0 cm 2):
Area Factor:
Design DCGLemc (dpm/100 cm 2):
LBGR (dpm/100 cm2):
Design Sigma (dpm/100 cm 2):
Type I Error:
Type II Error:
Predominant Nuclide:
Sample Area (m2):
Scan Area (m 2):
Scan Coverage (%):
Zi-P Sign P:
Calculated Relative Shift:
Relative Shift Used:
IN-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
0305 2
847 D. Anderson 43,000 N/A N/A 37,831 1,723 0.05 0.05 Cs-137 60.5 233 28%
1.645 1.645 0.99865 3
3 11 14 14 7.5 South Turbine Deck (+) 40' El.
Structure Surface LTP Table 5-4 Gross Activity DCGL Class 2 Class 2 Adjusted Class 2 Class 2 Uses 3.0 if Relative Shift is
>3 NUREG-1575 Table 5-5 Class 2 Class 2
.1.
Page 3 of 8 FSS Summary Report F8260305
Survey Results:
A total of 21 direct measurements were made in F8260305. 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. All ISOCS gamma measurements were less than the Cs-137 and Co-60 MDAs.
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.Activity (dpm/100 cm F8260305-MOOOI BD 1,619 F8260305-MOO02BD 2,032 F8260305-MOO03BD 1,881 F8260305-MOO04BD 1,857 F8260305-MOOO5BD 2,000 F8260305-CO006BD 1,712 F8260305-CO007BD 1,784 F8260305-CO008BD 2,023 F8260305-CO009BD 1,561 F8260305-CO01 OBD 1,650 F8260305-CO01 I BD 1,940 F8260305-CO01 2BD 2,090 F8260305-CO013BD 1,.961 F8260305-CO014BD 2,070 F8260305-CO015BD 1,867 F8260305-CO016BD 1,971 F8260305-CO017BD 1,738 F8260305-CO01 8BD 1,665 F8260305-CO01 9BD 1,349 F8260305-MO02OBD 1,746 F8260305-M0021 BD 1,762 Mean:
1,823 Median:
1,857 Standard Deviation:
191 Range:
1,349 - 2,090 Page 4 of 8 FSS Summary Report F8260305
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8260305M0001 SM F8260305M0002SM F8260305M0003SM F8260305M0004SM F8260305M0005SM F8260305C0006SM F8260305C0007SM F8260305C0008SM F8260305C0009SM F8260305C0010SM F8260305C001 1 SM F8260305C0012SM F8260305C0013SM F8260305C0014SM F8260305C0015SM F8260305C0016SM F8260305C0017SM F8260305C0018SM F8260305C0019SM F8260305M0020SM F8260305M0021SM Mean:
Median:
Standard Deviation:
Range:
-0.95
-4.82
-2.24 4.22
-3.53
-3.53
-2.24
-2.24
-0.95
-4.82 1.64 0.34
-4.82
-2.24
-3.53
-0.95
-4.82
-4.82 0.34 0.34
-0.95
-1.93
-2.24 2.45
-4.82 to 4.22 Page 5 of 8 FSS Summary Report F8260305
Survey Unit Data Assessment:
The survey design required 21 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 F8260305
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm2):
N/A Ambient Background Used (dpm/100 cm 2):
N/A Average Ambient BKG = 0 Actual Direct Measurements (N):
21 Median (dpMlO00 cm2):
1,857 Mean (dpm/100 cm2):
1,823 Direct Measurement Standard Deviation 191 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm 2):
191 Based on samples and backgrounds.
Maximum (dpm/100 cm 2):
2,090 Material Type:
N/A Background Subtract Not Applied Sign Test Final N Value:
21 S+ Value:
21 Critical Value:
14 Sufficient Samples Collected:
Yes Maximum Value < DCGL:
Yes Median Value < DCGL:
Yes Mean Value < DCGL:
Yes Maximum Value < DCGLemc:
N/A Class 2 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 F8260305
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), the ALARA criterion has been met.
Changes in Initial Survey Unit Assumptions:
The survey unit was designed as a Class 2 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.
==
Conclusion:==
The FSS of this survey unit was properly designed as a Class 2 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 43,000 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 F8260305 meets the release criteria of 10CFR20.1402.
Page 8 of 8 PFSS Summary Report F8260305
Attachment I Maps March 20, 2008 Survey Unit F8260305
0O 00 CjO
('J F8260303: North Turbine Deck F8260304: Center Turbine Deck F8260305: South Turbine Deck Area Estimate: 815 sq. meters Area Estimate: 953 sq. meters Area Estimate: 847 sq. meters Map F8260305-1, Turbine Building Deck (+) 40' El.
Area Estimate: 2,615 sq. meters (3 survey units - Class 2)
N 0
2 4
6 8
Distance in Meters Location of Turbine Building inside the Industrial Area
N 0
2 4
6 8
Dttonco i. Motors Map F8260305-2, South Turbine Deck (+) 40' El.
Area Estimate: 847 sq. meters Page 3 of 7 Att. 1 Maps F8260305
(D~
F8260303: North Turbine De ck 24 Beta Direct Measurements F8260304: Center Turbine Deck 16 Beta Direct Measurements Random Start Location:
5 m from south edge of turbine deck, 2 m from west edge of grating ITI 00 LA N4-0 24 6
8 Dsn in M.1-~
Map F8260305-3, Turbine Building Deck (+) 40' El.
Class 2 Beta Direct Measurements 7.5 m by 7.5 m grid spacing
Map F8260305-4, South Turbine Deck (+) 40' El.
Beta Direct Measurements F8260305M0001 BD to F8260305M0005BD, F8260305C0006BD to F8260305C0019BD, and F8260305M0020BD to F8260305M0021BD 7.5 m by 7.5 m grid spacing Distance in meters from west edge of turbine deck (nonstairway edge) 38.1 m 5 D16 D
30.6m
-0 12 0
0-~0--
3l 23.1 m 0
0 O
15.6 m (op o
0 0
ID__
7-D 8
8.1 m 0
0 0
0 S4BD 5BD 0.6 m 0.
12.5m 5.0m 2.5m 10.0l m C-D N
( C 0
2 4
6 8
Distance in Metem 20.0 m Page 5 of 7 Att. 1 Maps F8260305
ON 0
F8260303: North Turbine Deck 42 ISOCS Gamma Scan Measurements F8260304: Center Turbine Deck 53 ISOCS Gamma Scan Measurements F8260305: South Turbine Deck 22 ISOCS Gamma Scan Measurements 00 0\\
N 0
2 4
6 8
Distr in Mea.'s Map F8260305-5, Turbine Building Deck (+) 40' El.
ISOCS Gamma Scan Measurements 12.57 sq. meter field of view
N 0
2 4
6 8
Distance in Moters Map F8260305-6, South Turbine Deck (+) 40' El.
ISOCS Gamma Scan Measurements F8260305C0001 GS to F8260305C0022GS 12.57 sq. meter field of view centered on drains Approximate Scan Area: 233 sq. meters Page 7 of 7 Att. 1 Maps F8260305 Instrumentation March 20, 2008 Survey Unit F8260305
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; 175834 43-68B; 190482 433 1,033 Tennelec; 0401171 N/A 5.88 dpm a, N/A IT_
11.71ldpmf MDC Concrete-998 dpm/100 cm 2 Cs-137, Concrete-740 dpm/100 cm 2 Co-60 Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/lOO cm 2)
Investigation Criteria - Direct 43,000 Investigation Criteria - Scan 4,300 (ISOCS average activity)
DCGLw 43,000 DCGLEMc N/A Page 2 of 2 Ant. 2 Instrumentation F8260305 Investigation March 20, 2008 Survey Unit F8260305 (none required)
Data Assessment March 20, 2008 Survey Unit F8260305
00 C)~
F8260305 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm 2 3,000 -
2,500 -
2,000 -
1,500 -
1857 1,000 500 0
0 20 40 60 80 100 Percentile Direct Measurements (dpm/100cm2) median -
- - 75th Percentile.
50th Percentile
0 P8260305 Gross Activity Sample Results Scatter Plot
"*1 DCGL = 43000 dpmll00cm' 3000.
N2500mmmmmmmmmmmmmmmmmmmmmmmmmmmm29 0
0 0
83 2000 o
C-
-. a
- r c
-i
-r-b j1823 1500 Act a -
-A-v-e--
+-3-e-v" 1-
-250 100 a
a 500 a0aC 00Ca 00 0
0 0C0rr0rr N
I GrsActlvfly Average -
"+3StDev" -
3te o.
0 U.'
00 cIj CI I'3 F8260305 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2 5-C C.0 4-3 2
1 0-LO T,.,,
(0 O
Bins - Upper End Value (dpm/1 OOcm2)