ML081610111

Final Status Survey Summary Report, March 19, 2008, Plant Effluent Water Course (SU1) Survey Unit F1000001

ML081610111
Person / Time
Site:	Rancho Seco
Issue date:	03/19/2008
From:	Donna Anderson Sacramento Municipal Utility District (SMUD)
To:	NRC/FSME
References
F1000001
Download: ML081610111 (26)

Text

Rancho Seco Final Status Survey Summary Report March 19, 2008 Plant Effluent Water Course (SU1)

Survey Unit F1000001 Prepared By:

Cý. 'n Date: %3/1q /40 FSS neer Reviewed By:

Date:

1. *I..

eWSEngineer Approved By:__

7 Date:__________

Dismantlement Superintendent, Radiological

FINAL STATUS SURVEY

SUMMARY

REPORT Survey Unit:

F 1000001, Plant Effluent Water Course (SUl)

Survey Unit

Description:

Operating History: This area was the release point for liquid effluents released from the plant. The area was impacted by both planned and unplanned liquid releases. Effluents were monitored under the operating RETS/REMP program. Operating records and the HSA document the release of radioactivity in this survey area. The HSA recorded multiple unplanned release events.

Site Characterization: Soil and sediment samples were collected and analyzed for the presence of plant-derived radionuclides. Cs-137 was the predominant nuclide with a mean activity level of 9.2 pCi/g and a maximum value of 48.2 pCi/g. The Characterization data were found to be conservative when compared to the historical information found in the reports referenced in the PDP. Based on the classification procedure (DSIP-0020), the area was determined to be a Class 2 land area.

HSA Events: ODR-740017, 740052, 750046, 760079, 810192, 810193, 810209, 83008, 830023, 830248, 840117, 840118, 840225, 840223, 850299, 850112, 860555, 870764, 870905.

J 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 4,580 m2 were scanned for approximately 55% coverage. Soil samples were collected at each direct measurement location and analyzed by HPGe detector. 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 FIO000001

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

F1100 Plant Effluent Water Course (SUl)

Survey Unit:

0001 Open Land Area Class:

2 LTP Table 5-4 SU Area (m2):

8,339 Evaluator:

D. Anderson DCGL for Cs-137 surrogate (pCi/g):

52.6 DCGL for Co-60 (pCi/g):

12.6 Area Factor:

N/A Class 2 Design DCGLemc (pCi/g):

N/A Class 2 LBGR (pCi/g):

27.8 Adjusted Design Sigma (pCi/g):

14.7 DTBD-06-001, Table 5-4A or B Type I Error:

0.05 Type II Error:

0.05 Sample Area (m2):

490.5 Class 2 Total Area Scanned (m2):

4,580 Scan Coverage (%):

54.9%

Class 2 ZI- :

1.645 ZI.* :

1.645 Sign P:

0.945201 Calculated Relative Shift:

1.6 Relative Shift Used:

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

14 Design N-Value + 20%:

17 NUREG-1575 Table 5-5 Grid Spacing L:

22.1 Class 2 Page 3 of 8 FSS Summary Report 171000001,

Survey Results:

A total of 19 direct measurements were made in F 1000001. The results are shown in Table 2-1. Statistical data including the mean, median, and standard deviation are shown in Table 2-2. All of the direct measurements were less than Unity. Soil samples were counted to the MDCs shown in Table 2-1 of Attachment 2.

Four adjoining ISOCS measurements indicated one area where the average activity exceeded the investigation level for a Class 2 soil survey. An investigation was performed and soil activity exceeding the DCGL of 52.6 pCi/g Cs-137,was identified.

The 11-meter by 18-meter area was subsequently remediated, reclassified as a Class 1 land area and surveyed under F 1000004.

Page 4 of 8 FSS Summary Report F 100000 1

Table 2-1. Direct Measurement Results (all activity values in pCi/g)

Cs137 Co60 Sample ID MDA Activity Uncertainty Unity MDA Activity Uncertainty unity Unity ty Value Value To tal F1000001SOOOISS 5.61E-02 3.64E-01 7.36E-02 0.0069 4.81E-02

<4.81E-02 0.0038 0.0107 F1000001S0002SS 7.64E-02 3.65E-01 7.61E-02 0.0069 5.88E-02

<5.88E-02 0.0047 0.0116 FIOOOOO1S0003SS 4.98E-02

<4.98E-02 0.0009 6.37E-02

<6.37E-02 0.0051 0.006 F1000001S0004SS 7.50E-02 4.38E-01 7.97E-02 0.0083 4.32E-02

<4.32E-02 0.0034 0.0118 F1000001S0005SS 5.98E-02 2.66E-01 6.13E-02 0.005 4.65E-02

<4.65E-02 0.0037 0.0087 F1000001S0006SS 5.53E-02 2.37E-01 6.36E-02 0.0045 4.73E-02

<4.73E-02 0.0038 0.0083 F1000001S0007SS 6.12E-02 2.57E-01 6.89E-02 0.0049 5.87E-02

<5.87E-02 0.0047 0.0095 F1000001S0008SS 4.94E-02

<4.94E-02 0.0009 5.31E-02

<5.31E-02 0.0042 0.0052 F1000001S0009SS 5.84E-02 2.57E-01 6.51E-02 0.0049 5.89E-02

<5.89E-02 0.0047 0.0096 FI00000ISOOISS 7.62E-02 7.38E-01 1.20E-01 0.014 6.57E-02

<6.57E-02 0.0052 0.0192 F100000ISOO11SS 1.08E-01 2.00E01 1.40E00 0.381 9.58E-02 2.29E-01 7.03E-02 0.0182 0.3992 F1000001SO012SS 7.21E-02 4.30E-01 7.98E-02 0.0082 6.00E-02

<6.00E-02 0.0048 0.0129 FIOOOOO1S0013SS 6.15E-02 5.27E-01 1.03E-01 0.01 4.92E-02

<4.92E-02 0.0039 0.0139 F1000001SO014SS 6.99E-02 1.70E00 1.41E-01 0.0322 8.70E-02

<8.70E-02 0.0069 0.0391 F100000ISOO15SS 6.57E-02

<6.57E-02 0.0012 6.18E-02

<6.18E-02 0.0049 0.0062 F100000ISOO16SS 7.19E-02

<7.19E-02 0.0014 6.05E-02

<6.05E-02 0.0048 0.0062 FIOO0001SOO17SS 7.54E-02 1.31E01 9.40E-01 0.2498 6.57E-02 1.30E-01 7.06E-02 0.0103 0.2601 F1000001SOO18SS 6.50E-02 1.18E00 1.19E-01 0.0225 5.76E-02

<5.76E-02 0.0046 0.0271 F100000IS0019SS 7.20E-02 1.26E00 1.54E-01 0.0239 7.33E-02

<7.33E-02 0.0058 0.0297 Page 5 of 8 FSS Summary Report F1000001

Table 2-2. Direct Measurements Results Summary Cs137 Co60

÷,

Activity Activity Cs137 Unity Co60 Unity Unity Total (PCi/g)

(pCijg)

DCGLw 52.6 12.6 Mean 2.18E00 7.12E-02 0.0415 0.0056 0.0471 Median 3.65E-01 5.89E-02 0.0069 0.0047 0.0116 Standard Dvation 5.23E00 4.28E-02 0.0993 0.0034 0.1026 Deviation Cs137 Activity Range (pCi/g) 4.94E-02 to 2.OOEO1 Co60 Activity Range (pCi/g) 4.32E-02 to 2.29E-01 Cs137 Unity Range 0.0009 to 0.381 Co60 Unity Range 0.0034 to 0.0182 Total Unity Range 0.0052 to 0.3992 Sample Count 19 Survey Unit Data Assessment:

The survey design required 19 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 6 of 8 FSS Summary Report F1000001

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

19 Median (Unity):

0.012 Mean (Unity):

0.047 Direct Measurement Std Deviation (Unity):

0.103 Maximum (Unity):

0.399 Sign Test Final N Value:

19 S+ Value:

19 Critical Value:

13 Sufficient Samples Collected:

Yes Maximum Value < Unitized DCGL:

Yes Median Value < Unitized DCGL:

Yes Mean Value < Unitized DCGL:

Yes Maximum Value < DCGLemc (Unity):

N/A Class 2 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 FIO000001

Survey Unit Investigations and Results:

One investigation (scan grids 128, 129, 130 and 166) was required for the scan measurements and the results are reported in Attachment 3. As a result of the investigation, soil activity exceeding the DCGL of 52.6 pCi/g Cs-137 was identified. The 11-meter by 18-meter area was subsequently remediated, reclassified as a Class 1 and surveyed under F 1000004.

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 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. One potential area of elevated activity was detected and evaluated as shown in Attachment 3. The area of investigation was remediated, reclassified and surveyed under F 1000004.

==

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. All of the direct measurements were less than Unity. One investigation was required. The 11-meter by 18-meter area was subsequently remediated, reclassified as a Class 1 and surveyed under F 1000004.

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 F 1000001 meets the release criteria of IOCFR20.1402.

Page 8 of 8 FSS Summary Report FIO000001 Maps March 19, 2008 Survey Unit F1000001

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SURVEY AREA CONFIGURATION TOTAL SIZE OF SURVEY AREA: 21,285 SQ M SCALE METERS 0l=1.01

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Map F1000001-3, Plant Effluent Water Course (SU1)

ISOCS Gamma Scan Measurements F1000001 SO001 GS to F1000001 S0200GS 28 sq. meter field of view, 5 meter centers 0Total Scan Area: 4,580 sq. meters 0

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IOS 1170 ISncs FIELO OF VIEW4, 28 n2 ON 5 METER CENTERS MAP F1000001-6, GAMMA SCANS F1 000001 S0120GS-Fl000001O01 S68GS TOTAL SCAN AREA:

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Map X1000001-1, Plant Effluent Water Course (SU1)

Elevated ISOCS Gamma Scan Measurements 28 sq. meter field of view 0

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Area surveyed as F1000004 (Class 1)

ISOCS scans are 28 sq. meter field of view, 6 meters in diameter CD, ISOCS 130GS:

19.3 pCi/g Cs-137 I

ISOCS 129GS:

22.9 pCi/g Cs-137 I

ISOCS 128GS:

23.3 pCi/g Cs-137 I

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18.8 pCi/g Cs-137 Map X1000001-2, Plant Effluent Water Course (SU1)

Investigation Gamma (Nal) Scan Measurements X1000001 S0201GS to X1000001 S0212GS Investigation Soil Samples X1 000001 S0001SS to X1 00000 1S0004SS Instrumentation March 19, 2008 Survey Unit F1000001

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

HPGe N/A 9987008 Soil - 1.08E-01 pCi/g Cs-137 Soil - 9.58E-02 pCi/g Co-60 SN/A 05047773 Soil - 7.64E-02 pCi/g Cs-137

.Soil - 8.70E-02 pCi/g Co-60 N/A 2983947 Soil - 3.67E-01 pCi/g Cs-137 Soil - 2.91E-01 pCi/g Co-60 Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value ISOCS Investigation Criteria - Scan Soil - 20 pCi/g Cs-137 1 All DCGLw 52.6 Cs-137 12.6 Co-60.

All DCGLEMC N/A Based on detecting a 1 m2 hot spot within the 28 m2 detector field of view Page 2 of 2 Att. 2 Instrumentation F1000001 Investigation March 19, 2008 Survey Unit F1000001

Table 3-1 Survey Unit Investigation Investigation Initial Value Investigation Elevated Area Investigation DCGLemc Grid Level (Cs-137pCi/g)

Result Area (m2)

Factor DCGLemc Iestigation Unity (Cs-137pCiig)

(p

)

A m____ Fcto Result (pCi/g)

Fraction

128, 20 23.3 69.8 N/A N/A 11 m by 18 m area 129 20 22.9 81 11 m by N/A N/A remediated, reclassified as 130 20 19.3 73.3 18 m N/A N/A Class 1 and surveyed under F1000004 166 20 18.8 38.2 N/A N/A Survey Unit Remainder DCGL SU Mean N/A 52.6 EMC Unity Sum N/A NOTE: ISOCS instrumentation measures average activity within the detector field of view. The Investigation Level for the 28 sq. meter field of view used within this survey unit is based on detecting a 1 m2 area of elevated activity at the edge of the field of view. Nal scans and soil sampling were used to locate the elevated activity and determine the extent of the area requiring remediation.

Page 2 of 2 Att. 3 Investigation FIO00000I Data Assessment March 19, 2008 Survey Unit F1000001

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