ML082620150
| ML082620150 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/13/2008 |
| From: | Tallman D Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| MPC&D 08-064 | |
| Download: ML082620150 (23) | |
Text
Rancho Seco Final Status Survey Summary Report June 13, 2008 AB Western Stairwell -10' to grade including TF transition Survey Unit F8130091 Pre pared By: Dan A. Tallman Date: June 13, 21008 FSS Engineer ReviewedBy:- __ /U- DateB:il/1*/0 Lead FSS Engineer Approved By: 7/ Date: 7- -
Dismantlement S'perintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8130091, AB Western Stairwell -10' to grade including TF transition.
Survey Unit
Description:
Operating History: The Auxiliary Building is a reinforced concrete structure that 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.
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. The direct measurements on the -20' elevation showed a mean gross activity level of 247,831 dpm/1 00 cm 2 and a maximum value of 10,080,000 dpm/100 cm2 . Direct measurements on the grade elevation showed a mean gross activity level of 373,758 dpm/100 cm2 and a maximum value of 5,800,000 dpm/100 cm 2 . Direct measurements on the building exterior, including the mezzanine roof, showed a mean gross activity level of 1,897 dpm/100 cm 2 and a maximum value of 2,990 dpni//100 cm 2 . Based on the classification procedure (DSIP-0020) and levels of gross activity reported, Survey Unit 8130091 within the interior, transitioning to the exterior, of the auxiliary building was determined to be a Class 3 area.
HSA Events: HSA Report pg. 63.
Survey Unit Design Information:
The Survey Unit Design Parameters are presented in Table I-below. The survey unit and measurement locations are depicted on the maps in Attachment 1. Direct measurement locations were randomly determined and 20 m2 were scanned for approximately 11%
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 F8130091
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F813 AB Western Stairwell -10' to grade including TF transition Survey Unit: 0091 Structure Surface Class: 3 LTP Table 5-4 SU Area (m2): 178.1 Evaluator: D.A.Tallman 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'): 21500 Default = 50% DCGL 2
Design Sigma (dpm/100 cm ): 6935 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): N/A Class 3 Scan Area (M2 ): 20 Scan Coverage (%): 11% Class 3 1.645 Zip: 1.645 Sign P: 0.99865 Calculated Relative Shift: 3.1 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 3 of 8 FSS Summary Report F8130091
Survey Results:
A total of 14 direct measurements were made in F8130091. 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 2912 to 7175 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/lO0 cm F8130091 -COOOI BD 1198 F8130091-CO002BD 2505 F8130091-CO003BD 1069 F8130091 -CO004BD 1266 F8130091 -CO005BD 1136 F8130091-CO006BD 1380 F8130091-CO007BD 1494 F8130091-CO008BD 1302 F8130091 -CO009BD 1281 F8130091-COOIOBD 1203 F8130091-CO011BD 1198 F8130091-Co012BD 1292 F8130091-Co013BD 1266 F8130091-CO014BD 1369 Mean: 1354 Median: 1273 Standard Deviation: 348 Range: 1069-2505 Page 4 of 8 FSS Summary Report F8130091
Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm 2)
F8130091C0001SM -2.24 F8130091CO001SM -4.82 F8130091C0002SM -0.95 F8130091CO003SM -3.53 F8130091C0004SM -2.24 F8130091 C0005SM -4.82 F8130091C0006SM -3.53 F8130091 C0007SM 1.64 F8130091C0008SM -3.53 F8130091 C0009SM -2.24 F8130091CO010SM 2.93 F8130091C0011SM -3.53 F8130091C0012SM 0.34 F8130091C0013SM 1.64 F8130091C0014SM -2.24 Mean: -1.81 Median: -2.24 Standard Deviation: 2.42 Range: -4.82 to 2.93 Page 5 of 8 FSS Summary Report F8130091
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 Page FSS 6of8 Summary, Report F8130091 F109
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/lO0 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): 1273 Mean (dpm/100 cm 2): 1354 Direct Measurement Standard Deviation 348 2
(dpm/100 cm ):
Total Standard Deviation (dpm/100 cm 2): 348 Based on samples and backgrounds.
Maximum (dpm/100 cm 2): 2505 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 7 of 8 FSS Summary Report F8130091
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 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 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 F8130091 meets the release criteria of 10CFR20.1402.
Page 8 of 8 FSS Summary Report F8130091
Attachment 1 Maps June 13, 2008 Survey Unit F8130091
TOP Door 0 S Facing 00 ELEV. -_ .
Room 127 Staftwel Looking West Room 127 StaorwelLoodrig East
.1 Room 127 Sta 1.
o Grade Lesel
-113' -IC Floor 0 Floor KEY PLAN 0-0 Scale Feet ESTIMATED SURFACE AREA AUXILIARY BUILDING EL. 0" TO 0'-O" CJ) 02 Scale.Meters ROOM 127 STAIRWELL Wals 40.5 nml Floor 10.0 m? GENERAL AREA LAYOUT Coaing 9.5mn ESTIMATED SURFACE AREA 1 2 3 SACRAMENTO MUNI*PAL Talal 60.0mr UTILITY DISTRICT W F8130091-Mi T C HILL IDWG; 813000.03C 1 SHEET I OF 2
Il ELEV.19r-2' if ~
A CDj I'~l II CI ELEV.-(Y NorthwestWal East Wal South Wal West Wal I
Roof Enclosure Roof Stairwell Enclosure 00 w* Scale Feet C) ESTIMATEDSURFACEVAREA AUXILIARY BUILDING EL. V-0" WaJb Flom Coltng 94 3of 4O.3, 113Sm' 8" = 1P0" Scale Meters 100 SmuDl ROOM 138 GENERAL AREA LAYOUT ESTIMATED SURFACE AREA SACRAMENTO MUNICIPAL ToWt iSAm. UTILIFY DISTRiCT F8130091-Mi 0 1 2 3 DWG: 813000.03c SHEET 2 OF 2 T C. HIl I
.,,..i T
- 3:14 .... .: 4-4 0
{i,,'F T 00
-71 -7 ,.l ,. .
I : i, ...-
12.~~~~ "1--
+
!4+4+A ......... ~~~~1....
44-4-1 .... ... . ....
.... 1f1 1 T- ll t1 ! ! 1 .. .. .. +1!
w -X.T T
T RADO MESRMNTLCTO
- !.- .......I 3~~ ~ ~ ~~~ ~~~~~~~
,,* :I:I*III
. ... :7 . . . . . . ......
-,L 1 . * *s ,
UTwIT 81 09 M2.. 7 I,
- 2
- 71 pITRC- -- * .( 1 t .] f 5 I
~~ ~ ~ ~ ~ ~~~~
W( 1 7 R 12 Xa 406 0~
00 w,
CD ELEV. 8-00 SELEV. a ELEV.,-8 Room 127 North Wal (J*
Reflected Cei lig ELIEV-e Room '27 Slairwell Looft East GDiN Col~fl Goua Lest Room -1111 127.Reflected Staivell Coding Coiling -V0" I
II Rom1I tis I GaeLoo IYbr I Finrn KEYPLAN 00 Scale Feet AUXILIARY BUILDING EL.-10O0" AND W-01" Scale Meters ROOM 127 BETA DIRECT/LOOSE SMuO SURFACE ACTIVITY MEASUREMENT LOCATIONS o 1 2 3 SACRAMENTO MUNICIPAL UTILITY DISTRICT F810091-M2 TC HILL DJWG:813000.03c SHEET 2 OF 3 DWC:813000.03c SHEET 2 OF 3 T C HILL
ELEV.19r-2 O'Q ONx 0
00
-4 ELEV.-U Wall North~west EastWall South Wag WestWall I
Rout Enclosure Roof KEY PLAN Stairwell Enlo+/-sure 00 w Scale Feet AUXILIARY BUILDING EL.-10-0" AND 0'-10" st"= 1'-0"s ROOM 138 BETA DIRECT/LOOSE Scale Meters I.S MUD0 53 SURFACE ACTIVITY MEASUREMENT LOCATIONS SACRAMENTO MUNICIPAL LF1LI[Y DISTRICT F810091-M2 0 1 2 3 .03c SHEET 3 OF 3 T C HILL
] ...........
00
/'(NTS)
Reflected Ceiling Cross nSectio-
/TS Room 1,27. Starwel L-ookig East
/" ;z P. .!
I FCOD-11 F Iý Room 127 Reflected Staiwel CA61g Coiling Grourd Level Coiling -1a Iii Room 127 Stairs -1I" to Grade Level -1'Fbo~r 9 Fbor KEYPLAN 0T0 00 Scale Feet I"8= 1,-0" AUXILIARY BUILDING EL.-1O0-" AND 0'-0" Scale Meters ROOM 127 STAIRWELL BETA SCAN SSMU13 MEASUREMENT LOCATIONS 1 2 3 SACRAMENTO MUNICIPAL UTULrTYDISTRICT F81 0091 -M3
-' i-ll I 03c SHEET I OF 2 C HILL
ELEV. 19-Z A4 00 0
0 ELEV.-Y Northwest Wal E*at Wal South Wall Wost Wall L-Root Enclosure Roof KEY PLAN Stairwell Encosura 00 Scale Feet AUXILIARY BUILDING EL.-10-0" AND 0'-0" w
I"= 1,'-0" ROOM 138 BETA SCAN Scale Meters *smun MEASURMENT LOCATIONS SACRAMENTO MUNICIPAL UTiLITY DISTRICT F810091-M3 0 1 2 3 frWC~ Ni 'CICV I.03c SHEET 2 OF 2 T C HILL OWC:813000
Attachment 2 Instrumentation June 13, 2008 Survey Unit F8130091
Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No. Model; Serial No. (dpm/100 cm 2 ) (dpm/100 cm 2 )
M2350; 203486 43-68B; 190476 433 1033 Tennelec; 0401171 N/A 6 dpm a, 12 dpm3 N/A Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 cm 2)
Investigation Criteria - Direct 21500 Investigation Criteria - Scan 43000 DCGLW 43000 DCGLEMC N/A Page 2 of 2 Att. 2 Instrumentation F8130091
Attachment 3 Investigation June 13, 2008 Survey Unit F8130091 (none required)
Attachment 4 Data Assessment June 13, 2008 Survey Unit F8130091
CF8130091 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/100cm2 3,000 2,5000
.> 2,00"0 **i*,
1,500 En ** 1273 500.
0 0 20 40 60 80 100 Percentile
-. ** Direct Measurements (dpm/100cm2) -median - - - 75th Percentile - -- - 50th Percentile C:)
0C F8130091 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmll00cm' 3000 F? 2500 a a - a a a a a a E aa - -a a a -a a- a a 502000
- -o- a -- o - __ -- o 00 1354 0 0 0 00 -
0 0 1000
"~500 aa a - a a - - a a a a- a - a a a a a a a a a-310 0
U MU U U Lato Uen U U Measurement Locations
.71 00 Uj 1 0 Gross Activity - Average - - "+3StDev" - - "-3$tDev "I C)
C)
F8130091 Gross Activity Frequency Plot 2
DCGL = 43000 dpm/1 00cm 13 12 11 10 9
8 U- 7 C
.0 6 (j) 5 4
3 2
En 1 0
CO-'
00 Bins - Upper End Value (dpm/100cm2)