ML082620091
| ML082620091 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/03/2008 |
| From: | Stein M Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-064 | |
| Download: ML082620091 (19) | |
Text
Rancho Seco Final Status Survey Summary Report June 3, 2008 Stairwell # 3 Rooms 210 and 318, Above Elevation 20'- 0", Auxiliary Building Survey Unit F8131402 Prepared By:_ __ _ Date:2* *0 .
FSS Engineer Reviewed By:\,-Date:.k/JL(0i Lead FSS Engineer Approved By: I 7 _ Date: 7- -
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8131402, Stairwell # 3 Rooms 210 and 318, Above Elevation 20'- 0" of the Auxiliary Building Survey Unit
Description:
Operating History: Stairwell # 3 is located in what used to be considered the radiologically controlled section of the Auxiliary Building. The stairwell was assigned three room numbers as follows. Room # 116 is the section of the stairwell from elevation 0'- 0" (grade level) to elevation 10'- 0". Room # 210 is the section of the stairwell from elevation 10'- 0" to elevation 31'- 3". Room # 318 is the section of the stairwell from elevation 31 '- 3" to elevation 52'- 0".
Site Characterization: Scan measurements for beta radiation were taken on the interior surfaces of Stairwell # 3. The measurements showed a mean gross activity level of 18,533 dpm/100 cm 2 and a maximum value of 192,616 dpm/100 cm 2 from grade level to elevation 20'- 0". The measurements showed a mean gross activity level of 4,595 dpmr/100 cm 2 and a maximum value of 10,529 dpm/l00 cm 2 above elevation 20'- 0".
Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior 'surfaces of Stairwell # 3, from grade level to elevation 20'- 0", were determined to be a Class 1 area and, above elevation 20'- 0", were determined to be a Class 2 area.
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 62 m2 were scanned for approximately 30% 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 F8131402
Table 1. Survey Unit Design Parameters Survey Design. Value Comment Parameter Survey Area: F813 Stairwell # 3 Rooms 210 and 318, Above Elevation 20'- 0", Auxiliary Building Survey Unit: 1402 Structure Surface Class: 2 LTP Table 5-4 SU Area (m2): 205 Evaluator: Michael Stein DCGL (dpm/100 cm 2): 43000 Gross Activity DCGL Area Factor: N/A Class 2 Design DCGLemc N/A Class 2 (dpm/100 cm 2 ):
LBGR (dpm/100 cm 2): 21500 Default = 50% DCGL Design Sigma (dpm/O00 cm 2): 5461 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 14.6 Class 2 2 62 Scan Area (m ):
Scan Coverage (%): 30% Class 2 1.645 1.645 Sign P: 0.99865 Calculated Relative Shift: 3.9 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 2
,3.8 Class 2 Grid Spacing L:
Page 3 of 8 FSS Summary Report F8131402
Survey Results:
A total of 14 direct measurements were made in F8131402. 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 5,472 to 29,276 dpm/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 Attachment 2.
Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm)
F8131402-COOOIBD 2105 F8131402-CO002BD 2359 F8131402-CO003BD 2271 F8131402-CO004BD 2535 F8131402-CO005BD 1400 F8131402-CO006BD 2447 F8131402-CO007BD 1797 F8131402-CO008BD 2480 F8131402-CO009BD 1576 F8131402-CO01OBD 1587 F8131402-COOIIBD 2469 F8131402-CO012BD 2568 F8131402-CO013BD 2811 F8131402-CO014BD 2469 Mean: 2205 Median: 2403 Standard Deviation: 440 Range: 1400-2811 Page 4 of 8 FSS Summary Report F8131402
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2 )
F8131402C0001SM -0.95
.F8131402C0002SM 0.34 F8131402C0003SM -3.53 F8131402C0004SM -2.24 F8131402C0005SM 0.34 F8131402C0006SM -0.95 F8131402C0007SM -2.24 F8131402C0008SM 4.22 F8131402C0009SM 1.64 F8131402C0010SM -0.95 F8131402C0011SM -4.82 F8131402C0012SM -2.24 F8131402C0013SM -3.53 F8131402C0014SM -4.82 Mean: -1.41 Median: -1.59 Standard Deviation: 2.51 Range: -4.82 to 4.22 Page 5 of 8 FSS Summary Report F8131402
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 F8131402
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/I 00 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): 2403 Mean (dpm/100 cm 2 ): 2205 Direct Measurement Standard Deviation 440 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 2 cm ): 440 Based on samples and backgrounds.
Maximum (dpm/100 cm 2). 2811 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 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 F8131402
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 Table5-4 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 supportrejection 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 F8131402 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8131402
Attachment 1 Maps JJune 3, 2008 Survey Unit F8131402
(D EL 40'-0' PLANLVIE ELEV. 201-01 EL 51-W~
EL 2S-2" EL 20'-0" LKG NORTH LKG SOUTH LKG WES' S".' 23Y-týj E.EY, 31'-3 0 1 2 3 4 SCALE METERS
ýlT AUXILIARY BUILDING EL 20 00 STAIR #3 ROOMS 210 & 318 BETA DIRECT/LOOSE SURFACE ACTIVITY MEASUREMENT LOCATIONS F8131 402-M2
(t~
a KEY PLANS PLAN VIEW REFLECTED CEILING VIEW REFLECTED CEILING VIEW ElE. 20-0" m"E. a1 l-0i-cj~ PLAN VIEW REFLECTED CEILING VIEW
.EUV. 27'--6 0E". t"-3" PLANV, IE EIEV.3V-7,t 00
- SCAN UNWTCosISS STAIR #3 RMS 210 & 318 FLOOR PLAN OF 3STAIR RIERS BETA SCAN AMD3 SDWJTREWDS MEASUREMENT LOCATIONS 0 - SCAL* 3E F8131402-M1
ý1300o.04c SHEET 1 of 2 RC RAYM
0 4-1 EL 0-EL 31-3j' EL 23-2' EL 20-0*
ELEV LKG NORTH ELEY LKG EAST ELEV LKG. SOUTH ELEV LXG WEST No~n ofOFL UNE 9.7 AT CO1 LINE R AT.VOL UNE 9,7 WESTOf COL Lm*
AUXILARY BUILDING EL 20 00 STAIR #* RMS 210 & 31B WALL ELEV BETA SCAN w.
0 1 2 3 S MUN MEASUREMENT LOCATIONS SCALE HKETE unf DtF81 31402-M1 Fnir Al A" 00- SHEET *2of 2 RC RAWIONE
Attachment 2 Instrumentation June 3, 2008 Survey Unit F8131402
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan 2
Model; Serial No. Model; Serial No. (dpm/100 cm ) (dpm/100 cm 2 )
M2350; 203486 43-68B; 190476 433 1033 Tennelec; 0401171 N/A 5.9 dpm 11.7 dpma,P3 N/A Table 2-2. Investigation Criteria and DCGL Value Param eter (dpm/100 cm 2 )2 V l eC Investigation Criteria - Direct 43000 Investigation Criteria - Scan 43000 DCGLw 43000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8131402
Attachment 3 Investigation June 3, 2008 Survey Unit F8131402 (none required)
Attachment 4 Data Assessment June 3, 2008 Survey Unit F8131402
F8131402 Gross Activity Sample Results Quantile Plot t'j 0 DCGL = 43000 dpm/1 00cm2 3,000 2,500 2403 2,000 cjý I 1,500 4-3J 1,000 500 0
0 20 40 60 80" 100 Percentile 00
- Direct Measurements (dpm/100cm2) -medlan - -. -75th Percentile . 50th Percentile C)
F8131402 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpm!100cm' 4000 3500 - -
a - - a a a -a - - a a- a a- - .
a 3524 E 3000 a o
-2500 -- o o - o o C) cL2000
> ,1500 *1~0 o0 0
- 1000 a
- ~~~~~ a a a am ami, a a a, , a a,
, a a a* a. aw a a,t a a a a am a
,- 887 500 0 " "
0 CA 00 0 0 00 0 In ImMeawuremenwtMLw M MtMons Measurement Locationis 0- o Gross Activity - Average - "+3StDev - - "3StDev k) I i ii ! l i il il I. l l i l li l[ I iW I . .
F8131402 Gross Activity Frequency Plot 2
DCGL = 43000 dpm/I OOcm 6
5 CD At) 4 0
3 2
1 "
ID- CT)2 0D IN- 0-T- T- CO- cc Itj 00 Bins - Upper End Value (dpm/l 00cm2)