ML090900733
| ML090900733 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 05/29/2008 |
| From: | Frank G Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| Shared Package | |
| ML090830613 | List:
|
| References | |
| DPG 09-097 | |
| Download: ML090900733 (18) | |
Text
Rancho Seco Final Status Survey Summary Report May 29, 2008 Clean Drain System "C" Holdup Tank Sump Cross Tie - Land Survey Unit F8990098 Prepared By Date: "
Reviewed By: 4' Date:4*Z**"
Lead FSS Engineer Approved By: eŽ[ ? / Date:_________
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8990098, Clean Drain System "C" Holdup Tank Sump Cross Tie - Land Survey Unit
Description:
Operating History: This system provided an alternate pathway for delivering feed water to the steam generators. This system was reported to have been contaminated as a result of steam generator primary to secondary tube leaks. Operating records and the HSA document occurrences of radioactive contamination associated with this system piping.
Site Characterization: Direct measurements were made of the interior surfaces of the system piping which confirmed the presence, of plant-derived radionuclides. Direct measurements of the interior showed a mean gross activity level of 368 dpm/100 cm2 and a maximum value of 634 dpm/100 cm2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported and since the pipe ran through a contaminated soil area, the survey unit was classified as a Class 2.
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 100.3 m2 were scanned for approximately 100% 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 7 FSS Summary Report F8990098
Table 1. Survey Unit Design Parameters Survey Design Parameter Value Comment Survey Area: F899 Clean Drain System "C" Holdup Tank Sump Cross Tie - Land Survey Unit: 0098 Open Land Area Class: 2 LTP Table 5-4 SU Area (m 2 ): 100.3 Evaluator: Gary Frank DCGL Cs137 surrogate (pCi/g): 51.2 Area Factor: N/A Class 2 Design DCGLemc (pCi/g): N/A Class 2 LBGR (pCi/g): 26.5 Adjusted Design Sigma (pCi/g): 0.034 DTBD-06-001, Table 5-4D Type I Error: 0.05 Type II Error: 0.05 Nuclide: Cs137 Sample Area (m): 7.2 Class 2 Total Area Scanned (m2): 100.3 Scan Coverage (%):. 100% Class 2 Zl-. : 11.645 ZIp : 1.645 Sign P: 0.99865 Calculated Relative Shift: 752.3 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: 2.7 Class 2 Page 3 of 7 FSS Summary Report F8990098
Survey Results:
A total of 14 direct measurements were made in F8990098. The results including mean, median, standard deviation and range are shown in Table 2. All of the direct measurements were less than the DCGL. Gamma scans were performed for discrete particle detection with results ranging from 7393 to 10864 cpm. Eight of the scan measurements indicated areas of elevated activity. Soil samples were collected and all were well below the DCGLw.
Table 2. Direct Measurement Results (all activity values in pCi/g)
Measurement ID Cs137 MDA Cs137 Activity Uncertainty mean: 1/2 K>ij4.65E-02 Median: > 4.50E-02 Standard Deviation: ... 7.8 1*E-03 Range: 3.42E-02 to 5.94E-02 F8990098S0001SS 5.57E-02 < 5.57E-02 F8990098S0002SS 5.07E-02 < 5.07E-02 F8990098S0003SS 4.24E-02 < 4.24E-02 F8990098S0004SS 3.42E-02 < 3.42E-02 F8990098S0005SS 4.34E-02 < 4.34E-02 F8990098S0006SS 4.66E-02 < 4.66E-02 F8990098S0007SS 4.74E-02 < 4.74E-02 F8990098S0008SS 5.73E-02 < 5.73E-02 F8990098S0009SS 5.27E-02 < 5.27E-02 F8990098S0010SS 4.02E-02 < 4.02E-02 F8990098S0011SS 3.53E-02 < 3.53E-02 F8990098S0012SS 4.26E-02 < 4.26E-02 F8990098S0013SS 4.33E-02 < 4.33E-02 F8990098SO014SS 5.94E-02 < 5.94E-02 Page 4 of 7 FSS Summary Report F8990098
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 F8990098
Table 3. Data Assessment Results Survey Results Parameter Value Comment Actual Direct Measurements (N): 14 Median (pCi/g): 4.50E-02 Mean (pCi/g): 4.65E-02 Standard Deviation (pCi/g): 7.8 1E-03
. Maximum (pCi/g): 5.94E-02 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 Standard Deviation <= Sigma: Yes Pass the Sign Test? Yes Reject the Null Hypothesis? Yes The survey unit passes all conditions? Yes Page 6 of 7 FSS Summary Report F8990098
Survey Unit Investigations and Results:
Eight investigations (scan grids 1, 2, 3, 4, 5, 7, 9, and 11) were required for particle scan measurements and none of the soil samples showed activity above fallout levels of Cs-137.
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 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. Eight potential areas of elevated activity were detected and evaluated as shown in Attachment 3.
==
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 the DCGL. Investigations were required and evaluated as shown in .
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 F8990098 meets the release criteria of 10CFR20.1402.
Page 7 of 7 FSS Summary Report F8990098
Attachment 1 Maps May 29, 2008 Survey Unit F8990098
o D=-
r---"-'cm
-7 E
"C" Holdup Cross Tie Line OILY WATER SEPARATOR Interior of pipe scanned with 44-157 for the entire 40 foot length at 6" increments.
11 gamma scans performed on 100%
of the trench and 50% of the spoil piles.
14 soil samples taken in the trench and the spoils pile.
t
'"U F8990098-M1 Page 2 of 3 Att. 1 Maps F8990098
Clean Drain System
'"'C" Holdup Tank 0 Sump Cross Tie Gamma Scans and Soil Samples
--N 40' Pipe 6" in diameter Spoils Pile S9GGf902' Q)G(4jS)SOS1GS(#J Trench cj~
07GS 05GS 03GS 01IGS 08GS 06GS 04GS 02GS It 00 00 F8990098-M2
Attachment 2 Instrumentation May 29, 2008 Survey Unit F8990098
Table 2-1. Survey Unit Instrumentation Detector Detector Serial Instrument Model No.MDC NNo.
HPGe N/A 05047773 Soil - 0.034 pCi/gCs- 137 2350-1 44-10 211672 5.2 pCi/g Table 2-2. Investigation Criteria and DCGL Instrument Parameter Value Soil - 25.6 pCi/g Cs-137 HPGe Investigation Criteria - Scan Soil -6.3 pCilg Co-13 Soil -6.3 pCi/g Co-60 All DCGLw 51.2 Cs-137 All 1 DCGw 12.6 Co-60 Page 2 of 2 Att. 2 Instrumentation F8990.098
Attachment 3 Investigation May 29, 2008 Survey Unit F8990098
Table 3-1 Survey Unit Investigation Inetigaio DCGLemc Investigation Initial Value Investigation Elevated Area DCGL Investigation Unity Gdves Ia Ve Result Area (m2) Factor (pCi/g) Result (pCi/g)
Fraction G (pCi/g) 01 7706 10389 0.0527 N/A N/A 51.2 <DCGL N/A 02 7706 9799 0.0433 N/A N/A 51.2 <DCGL N/A 03 7706 10193 0.0353 N/A N/A 51.2 <DCGL N/A 04 7706 10864 0.0426 N/A N/A 51.2 <DCGL N/A 05 7706 9474 0.0402 N/A N/A 51.2 <DCGL N/A 07 7706 7727 0.0474 N/A N/A 51.2 <DCGL N/A 09 7706 7809 0.0557 N/A N/A 51.2 <DCGL N/A 11 7706 7870 0.0466 N/A N/A 51.2 <DCGL N/A Survey Unit Remainder DCGL = SU0.0465 Mean = 0.0009 51.2 EMC Unity Sum N/A The investigation level was determined from measurements on the surface of the ground at the RHUT trench.
The area was determined to be a Class 2 and as such nothing was expected above the DCGLw. Grids were scanned for the highest reading. Two soil samples were obtained in the spoils pile (Grids 9, 10, 11) for the purposes of the investigation the higher value is used for investigation purposes.
Page 2 of 2 Att. 3 Investigation F8990098
Attachment 4 Data Assessment May 29, 2008 Survey Unit F8990098
F8990098 Quantile Plot Cs137 DCGL = 51.2 pCi/g 0.070 0.060 CD 0.050 0.045 U 0.040 00 .5 U
0.030 0.020 0.010 0.000 0 20 40 60 80 100 Percentile
- Activity - Median - - - 75th Percentile -- - - 50th Percentile I 00
CJQ 0
F8990098 Scatter Plot Cs137 DCGL = 51.2 pClIg B.OE-02 7.00E-02 3.07
, 6.00E-02 0 0 0 5.O0E-02 0 0
0- 0.047 0 0 0 0 4.OOE-02 0 0 0 z 3.OOE-02 cj~
. ........................... . 3.023 ci) 2.00E-02 1.DOE-02 0.001E+00 I I Measurement Locations S Actvty - Averaae - - "+3StDev - - - -3StDev 1rI 00 00
('D 0
F8990098 Frequency Plot Cs1 37 DCGL = 51.2 pCi/g 8
7 a) 6 5
IL 4
zl)
- 0) 3 (n
2 1
0 C,) &
C) &b-,
Bins - Upper End Value (pCi/g) 100 00