ML082620106

Final Status Survey Summary Report, April 1, 2008, Center Turbine Deck (+) 40' El., Survey Unit F8260304

ML082620106
Person / Time
Site:	Rancho Seco
Issue date:	04/01/2008
From:	Donna Anderson Sacramento Municipal Utility District (SMUD)
To:	NRC/FSME
References
MPC&D 08-064
Download: ML082620106 (24)

Text

Rancho Seco Final Status Survey Summary Report April 1, 2008 Center Turbine Deck (+) 40' El.

Survey Unit F8260304 Prepared By: !c.

• Date: 4-//2.,c*'

Reviewed By:_ Date: _____

t Lea*YFSS Engineer" Approved By: Date: 7 Dismantlemeht Sdt drintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F8260304, Center 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/1 00 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 cm2 and a maximum value of 6,980 dpm/100 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 cm2. 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/l100 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 cm2 . 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 693 m2 were scanned for approximately 73% 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 F8260304

Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area: F826 Center Turbine Deck (+) 40' El.

Survey Unit: 0304 Structure Surface Class: 2 LTP Table 5-4 SU Area (m2): 953 Evaluator: D. Anderson DCGL (dpm/100 Cm2): 43,000 Gross Activity DCGL Area Factor: N/A Class 2 Design DCGLemc N/A Class 2 (dpm/100 cm 2):

LBGR (dpm/100 cm 2 ): 37,831 Adjusted Design Sigma (dpm/100 cm 2): 1,723 Type I Error: 0.05 Type II Error: 0.05 Predominant Nuclide: Cs-137 Sample Area (m2): 68.1 Class 2 Scan Area (M2 ): 693 Scan Coverage (%): 73% Class 2 1.645 ZIP: 1.645 Sign P: 0.99865 Calculated Relative Shift: 3 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 Grid Spacing L: 8.2 Class 2 Page 3 of 8 FSS Summary Report F8260304

Survey Results:

A total of 16 direct measurements were made in F8260304. 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 F8260304-MOO01 BD 2,302 F8260304-MOO02BD 2,508 F8260304-MOO03BD 2,413 F8260304-CO004BD 1,971 F8260304-COOO5BD 2,049 F8260304-CO006BD 1,727 F8260304-CO007BD 1,276 F8260304-CO008BD 2,251 F8260304-CO009BD 2,049 F8260304-COOIOBD 2,039 F8260304-COOI I BD 2,044 F8260304-CO01 2BD 2,018 F8260304-CO01 3BD 1,950 F8260304-CO014BD 1,701 F8260304-CO015BD 2,646 F8260304-CO01 6BD 1,701 Mean: 2,040 Median: 2,041 Standard Deviation: 343 Range: 1,276 - 2,646 Page 4 of 8 FSS Summary Report F8260304

Table 3. Removable Surface Activity Results Measurement ID . Surface Beta Activity (dpmll00 cm 2)

F8260304M0001 SM -3.53 F8260304M0002SM 1.64 F8260304M0003SM -4.82 F8260304C0004SM -0.95 F8260304C0005SM -3.53 F8260304C0006SM 1.64 F8260304C0007SM 0.34 F8260304C0008SM 0.34 F8260304C0009SM 0.34 F8260304C0010SM -0.95 F8260304C001ISM -2.24 F8260304C0012SM -3.53 F8260304C0013SM -2.24 F8260304C0014SM -2.24 F8260304C0015SM 8.09 F8260304C0016SM -4.82 Mean: -1.03 Median: -1.59 Standard Deviation: 3.21 Range: -4.82 to 8.09 Page 5 of 8 FSS Summary Report F8260304

Survey Unit Data Assessment:

The survey design required 16 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 F8260304

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): 16 Median (dpm/100 cm 2): 2,041 Mean (dpm/lO0 cm 2): 2,040 Direct Measurement Standard Deviation 343 (dpm/100 cm 2 ):

Total Standard Deviation (dpm/100 cm 2): 343 Based on samples and backgrounds.

Maximum (dpm/100 cm 2): 2,646 Material Type: N/A Background Subtract Not Applied Sign Test Final N Value: 16 S+ Value: 16 Critical Value: 11 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 F8260304

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 and the EMC criterion has been met), 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/1 00 cm2 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 F8260304 meets the release criteria of IOCFR20.1402.

Page 8 of 8 FSS Summary Report F8260304

Attachment 1 Maps April 1, 2008 Survey Unit F8260304

00 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 01%

Map F8260304-1, Turbine Building Deck (+) 40' El.

Area Estimate: 2,615 sq. meters (3 survey units - Class 2) 00 UN C0 N P. Location of Turbine Building 0 2 4 6 8 inside the Industrial Area Distance in Meters

95 ft.- 29 m N

Map F8260304-2, Center Turbine Deck (+) 40' El.

o 2 4 6 8 Area Estimate: 953 sq. meters stane in Meters Page 3 of 9 Att. 1 Maps F8260304

0 00 0j

-C>

Distance in meters from west edge of turbine deck 15D 34D 38.1 m 0 0 q1 0 o 0 0 0 30.6 m o __o r-*r--

D8D .m.. . 2 35.0m 27.5m m

0. a Map F8260304-4, Center Turbine Deck (+) 40' El.a CD Beta Direct Measurements F8260304M0001BD to F8260304M0003BD, 0 24 6 8 O~islnc in Meters F8260304C0004BD to F8260304C0006BD, F8260304M0007BD and F8260304C0008BD to F8260304C0016BD 7.5 m bv 7.5 m ard sDacina Page 5 of 9 Att. 1 Maps F8260304

0(

0 pC F8260303: North Turbine Deck F8260304: Center Turbine Deck F8260305: South Turbine Deck 42 ISOCS Gamma Scan Measurements 53 ISOCS Gamma Scan Measurements 22 ISOCS Gamma Scan Measurements 00 N Map F8260304-5, Turbine Building Deck (+) 40' El.

0 ISOCS Gamma Scan Measurements 024 68 Distance in Mot= 12.57 sq. meter field of view

Distance in meters fr om west edge of turbine deck

.37.7 m C 047GeS 48 S e49GE-ES 50GS 51GS 52GS 53GS 0 0 0 46 S S 43GS 42GS 41 GS 40GS - 34.2 m 0

34GS 35 S S 39GS - 30.7 m A

31 S GS 30GS 29GS 28GS 27GS 27.2 m 20GS 21GS 22GS 23GS 24GS - 25GS 26GS 23.7 m 0 0 N, 4.1111,00 19GS C C C I ,

C 6 18GS17GS20.2m Low su Lo~w pen ý-s)ure

/T(01I

)pan__ 15GS S 9.7 m

~s I T 3S9-.-8-- 6.2 m G 12S 11 0

1GS 2GS 3GS 4GS 5GS 6GS k7GS 2.7 m

.AN, g

=:

12- ~ ~ j 1

~ .(5&

-44 I 30 3 3 B] 3 3B 3 CD0.

Map F8260304-6, Center Turbine Deck (+) 40' El.

ISOCS Gamma Scan Measurements F8260304C0001 GS to F8260304C0053GS, 0 2. 4 6 8 pista-c in Mwola 12.57 sq. meter field of view Approximate Scan Area: 607 sq. meters Page 7 of 9 Att. 1 Maps F8260304

00 0

1W 1 I1 F8260304: Center Turbine Deck 4 ISOCS Gamma Scan Measurements on Turbine Deck boxes 00 t'

N._ Map F8260304-7, Turbine Building Deck (+) 40' El.

ON ISOCS Gamma Scan Measurements 0 2 4 6 8 O~i_?'- i. ME~er F8260304C0054GS to F8260304C0057GS 11.8 sq. meter field of view Approximate Scan Area: 47 sq. meters

N ---or Map F8260304-8, Center.Turbine Deck (+) 40' El.

==VNNEZ=ý Beta Scan Measurements 8

2 0 Diswnm 6

4in Metem F8260304M0001BS to F8260304M0037BS, Approximate Scan Area: 39 sq. meters Page 9 of 9 Att. 1 Maps F8260304

Attachment 2 Instrumentation April 1, 2008 Survey Unit F8260304

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; 175834 43-68B; 190482 433 1,033 M2350; 175834 43-68B; 148634 433 1,033 M2350; 193715 43-68B; 148630 433 1,033 Tennelec; 0401171 N/A 5.88 dpm t, N/A 11.71 dpm P3 MDC Concrete - 1,420 dpm/100 cm' Cs-137, Concrete - 740 dpm/100 cm 2 Co-60 Table 2-2. Investigation Criteria and DCGL Value Parameter (dpm/100 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 Att. 2 Instrumentation F8260304

Attachment 3 Investigation April 1, 2008 Survey Unit F8260304 (none required)

I

Attachment 4 Data Assessment April 1, 2008 Survey Unit F8260304

CD F8260304 Gross Activity Sample Results Quantile Plot DCGL = 43000 dpm/1 00cm 2 3,500 3,000 ct- 2,500.

2041 I:

2,000 00 4.. 1,500 1,000 500 Q) 0 0 20 40 60 80 100 Percentile

• Direct Measurements (dpm/1 00cm2) median - - - 75th Percentile . 50th Pbrcentile

CD (U

o VF8260304 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpmlO00=cn 3500 3000 -.-.-.-----------------.-----.------- - - - --------- 0 E 0 82500 0 0 0 0 2000 - -- -O- . 2040 S1500

>' 0 CD 1000 - - - - - - - - - - - - - -- - - - - - -- -- - 1012 CD)

<500 0 1 I I I I '

O 0 r r t- t- r t-o C 0 01 a 0 0 0 0 0 0 0 0 0 0 a U U U U U U U U U U U U Measurement Locations I [o Gross Activty- Average - - "+3StDev" -  %--3StDev NA

0 F8260304 Gross Activity Frequency Plot DCGL = 43000 dpm/1 00cm2 5

4 0cj) 3 j

C 2

1 0

(0 C"

83 I..-

0)S CO It1 00 Bins - Upper End Value (dpm/1 00cm2)