ML081580594
| ML081580594 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/28/2008 |
| From: | Ellen Brown Sacramento Municipal Utility District (SMUD) |
| To: | NRC/FSME |
| References | |
| F8990291 | |
| Download: ML081580594 (16) | |
Text
Rancho Seco Final Status Survey Summary Report March 27, 2008 Main Circ Water Piping System Survey Unit F8990291 Prepared By: /o.
DO Date: 312712oo6
~ FS~
gineer Reviewed By:
Date:
SIn LeA FSS Engineer Approved By:
2 Date:
Dismantlement Superintendent, Radiological
FINAL STATUS SURVEY
SUMMARY
REPORT Survey Unit:
F8990291, Main Circ Water Piping System Survey Unit
Description:
Operating History: This system transported clean water through the condenser and to the cooling towers in order to remove the latent heat of condensation. This system was known to be clean. Operating records and the HSA document one occurrence of radioactive contamination associated with this system piping.
Site Characterization: Direct measurements of the interior showed a mean gross activity level of 475 dpm/i00 cm 2 and a maximum value of 614 dpm/100 cm 2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the system was determined to be a Class 3 system.
HSA Events: PDQ-900085 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. The 90" I.D pipe constituted a confined space hazard to personnel so in situ gamma spectroscopy was used to preclude personnel entry into the pipe. An in situ measurement was obtained in each of four segments of the 90"diameter piping and 175 m2 were surveyed for approximately 4% coverage. 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 '
F8990291
Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter.
Survey Area:
F899 Survey Unit:
Class:
SU Area (m2)
Evaluator:
DCGL (dpm/lOO cm'):
Area Factor:
Design DCGLemc (dpm/100 cm2):
LBGR (dpm/100 cm 2):
Design Sigma (dpm/100 cm 2):
Type I Error:
Type 1I Error:
Predominant Nuclide:
Sample Area (m2):
Scan Area (m2):
Scan Coverage (%):
Zl-,,:
Sign P:
Calculated Relative Shift:
Relative Shift Used:
N-Value:
Design N-Value + 20%:
Design Min Samples N:
Grid Spacing L:
0291 3
4515 Erin L. Brown 100000 N/A N/A 50000 99 0.05 0.05 Cs-137 N/A 175 4%
1.645 1.645 0.99865 505 3
11 14 14 N/A Main Circ Water Piping System Piping LTP Table 5-4 Gross Activity DCGL Class 3 Class 3 Default =50% DCGL Class 3 Class 3 Uses 3.0 if Relative Shift is
>3 NUREG-1575 Table 5-5 Class 3 Class 3
.1.
Page 3 of 7 FSS Summary Report F8990291
Survey Results:
A total of 4 measurements were made in F8990291 which covered 100% of the accessible pipe surface. 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 measurements indicated areas of elevated activity. Scan activity ranged from 148 to 216 dpm/100 cm2, based on~the pipe detector efficiency.
Table 2. Direct Measurement Results Measurement ID Gross Activity (dpm/100 cm)
F8990291-MOO05GS 148 F8990291-MOO06GS 165 F8990291 -MOO07GS 154 F8990291-MOO08GS 216 Mean:
171 Median:
160 Standard Deviation:
31 Range:
148-216 Page 4 of 7 FSS Summary Report F8990291
Survey Unit Data Assessment:
The standard survey design would have required 14 direct measurements' for the Sign Test. However, 4 measurements covering 100 percent of the accessible pipe surface were made instead. 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 F8990291
Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/100 cm2):
N/A Ambient Background Used (dpm/100 cm2):
N/A Average Ambient BKG =.0 Actual Direct Measurements (N):
4 Median (dpm/100 cm 2):
160
- Mean (dpm/100 cm 2):
171 Direct Measurement Standard Deviation 31 (dpm/100 cm 2):
Total Standard Deviation (dpm/100 cm 2):
31 Based on samples and backgrounds.
Maximum (dpm/100 cm2):
216 Material Type:
N/A Background Subtract Not Applied Sign Test Final N Value:
4 S+ Value:
4 Critical Value:
4 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 6 of 7 FSS Summary Report F8990291
Survey Unit Investigations and Results:
No investigations were required 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 coverage met the requirement of Table 5-6 of the LTP. No direct measurements exceeded the DCGL of 100000 dpm/100 cm 2 or the grout limit of 21000dpm/100cm 2. 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 F8990291 meets the release criteria of I 0CFR20.1402.
Page 7 of 7 FSS Summary Report F8990291 Maps March 27, 2008 Survey Unit F8990291
0 0
I'D KE PLAN
-REMAINING UNDERGROUNDI PIPIM REMOVIED P*iNG COOUJNFWATER DETAIL I I
PIPING SUM,RY SIZE LENGTH 106'.
1490 LF
- 90"6 16811.
'4,6"p
'152 IF 24or i2a LFr 20"6 17 LF 8"o 76 LF AREA 3915 SM 179 SM 31 Sl 15 sm SMUD
.M*4ENTo MUNtCPAL TLTJTY DISTRICT MAIN CIRCULATION WATER UNDERGROUND PIPING F8990291 -Ml FILE-899066 SlIT I OF i RC RAYMOND SCALE METERS Instrumentation March 27, 2008 Survey Unit F8990291
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; ISOCS HPGe; 1983920 103 (Co60)
N/A M2350; ISOCS HPGe; 1983920 113 (Cs'37)
N/A Table 2-2. Investigation Criteria and DCGL Parameter Value (dpm/100lcm2)
Investigation Criteria - Direct 50000 Investigation Criteria-Scan N/A DCGLW 100000 DCGLEMC N/A.
Page 2 of 2 Att. 2 Instrumentation F8990291 Investigation March 27, 2008 Survey Unit F8990291 (none required)
Data Assessment March 27, 2008 Survey Unit F8990291
OD 00
ý00 C)3 F8990291 Gross Activity Sample Results Quantile Plot DCGL = 100000 dpm/l00cm2 I
350 300 250 200 150 100 160 50 0
0 20 40 60 80 100 Percentile Direct Measurements (dpm/1 00cm2) -
median -
- 75th Percentile -
- 50th Percentile
0C CD 0
I'D 0
t',
F8990291 Gross Activity Sample Results Scatter Plot DCGL = 100000 dpmfiOOcM2 300
~260 -
E E
"0 100-so-0 f
- m -
m -
264 171.
0 0
w w
m u
m a
m a
a a
m n
a m
a m
m m-
- 78 I.
to0 0
2 00CD 0002 0
0 00 VO 0
000 Measurement Locations Io Gross ActMty -
Average
"+3StDev" -
"-3StDev"
0o 41.
P CD U)W.
F8990291 Gross Activity Frequency Plot DCGL = 100000 dpm/1 00crrf 10 9
0) 8 7-6-
5-4 3
1 0
N-(0 N~
00 0
Bins - Upper End Value (dprn/1 00cm2)