ML082620121

Auxiliary Building Nseb (Pigeon) Alley, Survey Unit F8000103

ML082620121
Person / Time
Site:	Rancho Seco
Issue date:	05/27/2008
From:	Frank G Sacramento Municipal Utility District (SMUD)
To:	NRC/FSME
References
MPC&D 08-064
Download: ML082620121 (17)

Text

Rancho Seco Final Status Survey Summary Report May 27, 2008 Auxiliary Building NSEB (Pigeon) Alley Survey Unit F8000103 Prepared Reviewed Approved Date:

Date:

_g4 By:

Date:

__7- ___-

o Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8000103, Pigeon Alley Survey Unit

Description:

Operating History: This area covers the majority of Industrial Area soils exclusive of the building footprints and rail line in this area. Operating records and the HSA document no specific release of radioactivity in these survey areas however this area does border known contaminated areas. The HSA recorded no specific unplanned release events.

Site Characterization: Soil and sediment samples were collected and analyzed for the presence of plant-derived radionuclides. Cs-137 was the only detected nuclide of plant origin with a mean activity level of 0.062 pCi/g and a maximum value of 0.299 pCi/g.

(Site background levels of Cs-137 have been determined to be approximately 0.312 pCi/g.) As described in section 2 of the LTP, the area was evaluated using DSIP-0020 and was designated as Class 3.

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. Diiect measurement locations were randomly determined and 124 m2 were scanned for approximately 28%

coverage. NaI (InSpector 1000) spectrums vWere collected and analyzed for 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 7 FSS Summary Report F8000103

Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area:

F800 Pigeon Alley Survey Unit:

0103 Open Land Area Class:

3 LTP Table 5-4 SU Area (m):

443 Evaluator:

Gary Frank DCGL Cs137 surrogate (pCi/g):

51.2 Area Factor:

N/A Class 3 Design DCGLemc (pCi/g):

N/A Class 3 LBGR (pCi/g):

25.6 Default = 50% DCGL Design Sigma (pCi/g):

0.118 DTBD-06-001, Table 5-4D Type I Error:

0.05 Type II Error:

0.05 Nuclide:

Cs137 Sample Area (m2):

N/A Class 3 Total Area Scanned (m2):

124 Scan Coverage (%):

28%

Class 3 Z1-:

1.645 ZJ-P :1.645 Sign P:

0.99865 Calculated Relative Shift:

211 Relative Shift Used:

3 Uses 3.0 if Rel Shift >3 N-Value:

11 Design N-Value + 20%:

14, NUREG-1575 Table 5-5 Grid Spacing L:

N/A Class 3 Page 3 of 7 FSS Summary Report F8000103

Survey Results:

A total of 14 direct measurements were made in F8000103. The results including mean, median, standard deviation and range are shown in Table 2. All of the direct measurements were less than the DCGL. None of the scan measurements indicated areas of elevated activity. Six ISOCS concrete structure scans measured 982 to 1190 dpm/100cm 2 for Cs-137 and 656 to 894 dpm/1OOcm 2 for Co-60. Seven ISOCS asphalt scans measured 0.21 to 0.36 pCi/g Cs-137 and 0.17 to 0.28 pCi/g Co-60.

Table 2. Direct Measurement Results (all activity values in pCi/g)

Measurement ID.

Cs137 MDA Cs137 Activity Uncertainty Mean:~84E01:~

Median:

8.38E-01 Standard Deviation:

3,85E-02 Range:

8.O0E-01 to 9.37E-01 F8000103C0001GD 8.28E-01

< 8.28E-01 F8000103C0002GD 8.75E-01

< 8.75E-01 F8000103CO003GD 8.43E-01

< 8.43E-01 F8000103C0004GD 8.25E-01

< 8.25E-01 F8000103C0005GD 8.66E-01

< 8.66E-0l F8000103C0006GD 8.56E-01

< 8.56E-01 F8000103C0007GD 8.47E-01

< 8.47E-01 F8000103C0008GD 8.33E-01

< 8.33E-01 F8000103A0009GD 9.37E-01

< 9.37E-01 F8000103C001OGD 8.27E-01

< 8.27E-01 F8000103AOOIGD 8.10E-01

< 8.10E-01 F8000103CO012GD 8.OOE-01

< 8.OOE-01 F8000103C0013GD 8.26E-0l

< 8.26E-01 F8000103A0014GD 9.14E-0l

< 9.14E-01 Page 4 of 7 FSS Summary Report F8000103

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 3. 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 5 of 7 FSS Summary Report F8000103

Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N):

14 Median (pCi/g):

8.38E-01 Mean (pCi/g):

8.49E-01 Standard Deviation (pci/g):

3.85E-02 Maximum (pCi/g):

9.37E-01 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 Standard Deviation <= Sigma:

Yes Pass the Sign Test?

Yes Reject the Null Hypothesis?

Yes The survey unit passes all conditions?

Yes I Page 6 of 7 FSS Summary Report, F8000103

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 land 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 F.SS 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. All of the direct measurements were less than 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 F8000103 meets the release criteria of 10CFR20.1402.

Page 7 of 7 FSS Summary Report F8000103 Maps May 27, 2008 Survey Unit F8000103

0 55 50 F8001031 - IA Central Yard, Pigeon Alley InSpector Gamma Direct 01, 12, and 13 are 5.Om north of-the north wall of NSEB.

01 is 0.22m west, 12 is 0.72m east, and 13 is 3.8m east of.corner 5 AUXILIARY BUILDING 160'-11" TURBINE BUILDING 49m 4/

5.9m 01 1

NSEB T &R BUILDING GREEN is W-E BLUE is N-S 13.9m 1.

I'll 00 Co Co 5

ADSMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT INDUSTRIAL AREA CENTRAL YARD PIGEON ALLEY GAMMADIRECT F8001031-M1 u

5 U

lu b zu z!)

JU 35 4U 40 oU 00 (u

0 U

f

0D F8001031 - IA Central Yard, Pigeon Alley ISOCS Gamma Scan AUXILIARY BUILDING TURBINE BUILDING 3.2m T & R BUILDING NSEB Obstructions required ISOCS scan 2 moved to location shown above.

13.9m It00 C)

W SACRAMENTO MUNICIPAL UTILITY DISTRICT INDUSTRIAL AREA CENTRAL YARD PIGEON ALLEY ISOCS LAYOUT F8001031-M2 Instrumentation May 27, 2008 Survey Unit F8000103

Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No.MDC No.

Concrete - 0.80 pCi/g Cs-137 r N/A 08051294 Concrete - 0.735 pCi/gCo-60 Asphalt - 0.81 pCi/g Cs-137 Asphalt - 0.803 pCi/g Co-60 Concrete - 982 dpm/100cm2 Cs-137 Concrete - 656 dpm/100cm 2 Co-60 Asphalt - 0.21 pCi/g Cs-137 I__ _ Asphalt - 0.17 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value Asphalt - 25.6 pCi/g Cs-137 ISOCS Investigation Criteria - Scan Asphalt - 6.3 pCi/g Co-60 Concrete -21500 dpm/100cm2 Cs-137 Asphalt-51.2 Cs-137 All DCGLW Asphalt - 12.6 Co-60 Concrete - 43,000 Cs-137 Page 2 of 2 Ant. 2 Instrumentation F8000103 Investigation May 27, 2008-Survey Unit F8000103 (none required)

Data Assessment May 27, 2008 Survey Unit F8000103

0 U)

Cl)

Cl) 2T C0 w

F8000103 Quantile Plot Cs137 DCGL = 51.2 pCi/g

(.)0.

.5 0

'a:

0.960 0.940 0.920 0.900 0.880 0.860 0.840 0.820 0.800 0.780 0.838 0

20 40 60 Percentile 80 100 Activty -

Median -

- - 75th Percentile - - - - 50th Percentile

00 F8000103 Scatter Plot Cs137 DCGL = 51.2 pCIg 1.20E+00 1.CO E +00 984 0 "--T 0

--r C--

D.849 8.00E '

0 O

3.734

.73

_6.ooE-o1 4.OE-01 2.OOE-01 O.OOE+O0 I

I p p p.. p.

,.0:,

p,..

o Op CO.0 "0o p. S.O Measurement Locations 0

Actity -

Average "

" "+3SIDev" -

"-3SlDevO I

00 C)1 C0 F8000103 Frequency Plot Cs1i37 DCGL = 51.2 pCi/g 8

7 ca:6 a)-5 L-

• 2 0

1 0

N tlb<N N

N Bins - Upper End Value (pCi/g)