ML090850555
| ML090850555 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 08/12/2008 |
| From: | Frank G Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML090850555 (22) | |
Text
Rancho Seco Final Status Survey Summary Report August 12, 2008 South LaydownlSump Area Adjacent to the Turbine Building South Wall Survey Unit F8260261 Prepared B _J( _ Date: Y )?" 2)oa FSS Engineer Reviewed By: W D a Date: ZOte I
Lead FSS Engineer Approved By: Date:
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
- F8260261, Survey Unit
Description:
Survey Area: Industrial Area Central Yard, adjacent to the south end of the Turbine Building including three turbine building sumps.
Operating History: The open yard area was located in the center of the Industrial Area surrounding, but not including, the power block, the tank farm, the aux boiler pad, the RHUT, the rotor storage shed, warehouse "A" and the machine shop. The vast majority of the area is paved including the concrete pads of the transformer yard (identified as 839000 in the HAS and is summarized below). Operating records and the HSA document several nearby leaks or spills with the potential for a release of radioactivity associated with this survey area. The HSA documented the storage of radioactive material within the area that may have had the potential to contaminate the area.
Site Characterization: Paved areas were surveyed and found to have a mean value of 2,261 dpm/100 cm2 and a maximum of 3,930 dpm/100 cm2 . Based on the classification procedure (DSIP-0020), the area was determined to be a Class 3 area.
HSA Events: None Page 2 of 9 FSS Summary Report F8260261
Survey Area Classification 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 randomly determined and 574 m2 were scanned for approximately 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 3 of 9 FSS Summary Report F8260261
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F826 South Laydown/Sump Area Survey Unit: 0261 Structure Surface Class: 3 LTP Table 5-4 SU Area (m2): 574 Evaluator: Gary Frank DCGL (dpm/100 cm 2): 43000 Gross Activity DCGL Area Factor: N/A Class 3
- Design DCGLemc N/A Class 3 (dpm/100 cm 2):
LBGR (dpm/100 cm 2): 21500 Default = 50% DCGL 2
Design Sigma (dpm/100 cm ): 250 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137
.Sample Area (m2): N/A Class 3 Scan Area (m2): 574 Scan Coverage (%): 100% Class 3 ZI-.: 1.645 ZI.* 1.645 Sign P: 0.99865 Calculated Relative Shift: 86 Relative Shift Used: 3 Uses 3.0 if Relative Shift is
>3 N-Value: 11 Design N-Value + 20%: 14 NUREG-1575 Table 5-5 Design Min Samples N: 14 Class 3 Grid Spacing L: N/A Class 3 Page 4 of 9 FSS Summary Report F8260261
Survey Results:
A total of 14 direct measurements were made in F826026 1. 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 4732 to 9812 dpm/100 cm 2, based on a surveyor efficiency of 0.5 and no background subtracted. ISOCS scan activity ranged from 104 to 1210 dpm/I00cm 2 for Cs-137 and 135 to 882 dpmr/100cm 2 for Co-60. No direct measurements were required in the sumps as the random points fell outside. Eight smears were obtained to confirm the loose surface activity in the west sump. 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/lO0 cmr F8260261-AOOOIGD 1060 F8260261-AO002GD 1080 F8260261-AO003GD 1060 F8260261 -AO004GD 1060 F8260261-AO005GD 1040 F8260261-AO006GD 1030 F8260261-AO007GD 1050 F8260261-AO008GD 1140 F8260261-AO009GD 1040 F8260261-AOOIOGD 1090 F8260261-AO011GD 1030 F8260261-AO012GD 1000 F8260261-AO013GD 1040 F8260261-AO014GD 1050 Mean: 1055 Median: 1050 Standard Deviation: 33 Range: 100)0-1140 Page 5 of 9 FSS Summary Report F8260261
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpmll00 cm 2)
F8260261COOOISM -2.24 F8260261CO002SM -4.82 F8260261 C0003SM 2.93 F8260261 C0004SM 1.64 F8260261 C0005SM -2.24 F8260261CO006SM -6.11 F8260261CO007SM -2.24 F8260261 C0008SM 9.38 Mean: -0.46 Median: -2.24 Standard Deviation: 4.97 Range: -6.11 to 9.38 Page 6 of 9 FSS Summary Report F8260261
Survey Unit Data Assessment:
The survey design required 14 direct measurements for the Sign Tý-st. 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 F8260261
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 cm 2 ): 1050 Mean (dpm/lO0 cm 2): 1055 Direct Measurement Standard Deviation '33 2
(dpm/100 cm ):
Total Standard Deviation (dpm/100 cm 2): 33 Based on samples and backgrounds.
Maximum (dpm!100 cm 2): 1140 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: N/A: Class 3 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 Summary Report F8260261
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, the ALARA criterion has been met.
Changes in Initial Survey Unit Assumptions:
The survey unit was designed as a Class 3 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 3 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 hypothe:sis, 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 F8260261 meets the release criteria of 10CFR20.1402.
Page 9 of 9 FSS Summary Report F8260261
Attachment I Maps August 12, 2008 Survey Unit F8260261
CD~
South Laydown/Sump Area ISOCS 37.2m 15m Turbine Building o11 00 F8260261- M1
South Laydown/Sump Area 0 Particle Scan 37.2m f- . . . . . . . . . . . . . . . . . . .
Co 15m C11 U) 41 GS CO 00 C1 43GS ý39 GS 3.4m Deep 1m Deep Turbine Building 00 0
ON F8260261- M2
cjc~
(t~
South Laydown/Sump Area 0 Gamma Directs ON 37.2m 15 -I 14 13 12 11 09 10 08 14 13 9 11 8 06 15m 7 12 6 03 05 fn 5 0410 Sm #1 ump #2Sump#3 4
0 3
2 01 1
07 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 N 1 2 3 4 5 6 7 8 9 Turbine Building 00 ON ON F8260261 - M3
South Laydown/Sump Area 0C Sump Scans Top of Sump Sump "B" ISOCS at 4 meter from bottom.
2.44m N E l za ISOCS at 2.66 meter from bottom 1.2m ISOCS at 1.33 meter from bottom Top of Sump Sump "A" 1.2m cj~ Sump "C" 1.8m ISOCS at 2.75 meter from bottom 0
-1.8m E ISOCS at 2 meter from bottom Ln N',
ISOCS at 1 meter from bottom 1.8m T17 Beta Scans 00 Turbine Building t'J 2ý1 F8260261 - M4
0 OO
(',Z ' 3 . IIII ]
Are inid th ndsralAe 01 IN) So13 ubn Building at RacoS°ost ON C) Map Lo2at2on Southof LaydownlSump Ae Su of Turbine Sut RaydowSucm psrea
Attachment 2 Instrumentation August 12, 2008 Survey Unit F8260261
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpmll00 crr,2 ) (dpmll00 cm 2 )
M2350; 193700 44-10; 256101 N/A 5.2 pCi/g-Cs-137 M2350; 193700 43-68B; 190294 433 1033 InSpector IPROS-2, 03069793 100 - Cs-137 N/A ISOCS GC4019, 2983947 N/A Asphalt -
104 Cs-137 Tennelec; 0401171 N/A 6 dpm (x, 12 dprnj3 N/A Table 2-2. Investigation Criteria and DCGL Value Parameter, (dpml100 c:m 2)
Investigation Criteria - Direct 21500 Investigation Criteria - Scan 43000 DCGLw 43000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8260261
Attachment 3 Investigation August 12, 2008 Survey Unit F8260261 (none required)
Attachment 4 Data Assessment August 12, 2008 Survey-Unit F8260261
CD F8260261 Gross Activity Sample Results Quantile Plot 0 DCGL = 43000 dpm/1 00cm2 1,160 1,140 1,120 1,100 I
4-1,080 1,060 1050 CD cj~
1,040 CD 1,020 1,000 980 0 20 40 60 80 100
~-71 Percentile 00
- Direct Measurements (dpm/100cm2) -median -- -75th Percentile . 50th Percentile ON ON
CD 0a o* F8260261 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpml00=cma 1400
/0 1200 -15 CU)10200 - - - - - - ...... - - - - - - -
... - - - - .. .. 115 E 100 a .- --------- o.-o - --------- '-"- -- a* a--- -- o--. 1056
> C CaL
Ž 400 200 0 o ir ifq a V1 1
aff1 a (q
0 Pi a
0 fIn aff1 DM ff1 0
fIrk a f" af1 0C C a C aC a 0 a 0 a a 0 0 r a G-o Measurement Locations ..... isT- ;;-
~oGross Actlvty --- Average-a - "+Ste - -"3Sev1 00 t'3 C'
'-0 F8260261 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm 2 9
8 7
6 U- 5 00 0 4
3 2
Ci2 1
C:>
0 0
N-0 Bins - Upper End Value (dpm/1 Ocm2)