ML17065A060

Final Status Survey Summary Report, January 25, 2017, Iosb Embedded Pipe, Survey Unit F8300123

ML17065A060
Person / Time
Site:	Rancho Seco
Issue date:	02/24/2017
From:	Sacramento Municipal Utility District (SMUD)
To:	Office of Nuclear Material Safety and Safeguards
Shared Package
ML17065A032	List: ML17065A034 ML17065A035 ML17065A036 ML17065A037 ML17065A038 ML17065A040 ML17065A041 ML17065A046 ML17065A047 ML17065A048 ML17065A049 ML17065A051 ML17065A052 ML17065A053 ML17065A054 ML17065A055 ML17065A056 ML17065A057 ML17065A058 ML17065A059 ML17065A060 ML17065A061 ML17065A063 ML17065A064 ML17065A065 ML17065A066 ML17065A068 ML17065A069 ML17065A070 ML17065A071 ML17065A072
References
DPG 17-038
Download: ML17065A060 (14)

Text

Rancho Seco Final Status Survey Summary Report January 25, 2017 IOSB Embedded Pipe Survey Unit F8300123 FSS Engineer Approved By: ~ Date: .;z.h,/r-:7'.

ManaQer:anchC: Seco Assets

FINAL STATUS SURVEY F8300123 Survey Unit:

F8300123, Interim Onsite Storage Building (IOSB) Embedded Piping Survey Unit

Description:

Operating History: The drain and piping system in the IOSB collected liquids from the building either via trench drains (storage cells, DAW Bay, and Truck Bay), or via floor drains. Areas of elevated residual radioactivity were identified in close proximity to the trench drains or floor drains indicating the potential for a spill of radioactive liquid to have traversed down the embedded piping to the sump.

Site Characterization: Static measurements were collected every six inches of pipe run in all sections of th~ embedded piping. Measurements indicated residual radioactivity in the embedded piping of the hot cell drain. The highest measurement obtained in the embedded piping was collected in the hot cell drain line at 26,766 dpm. This value exceeds the level for grouting of piping listed in the RSLTP. Based upon this level, the drain line from the hot cell was classified as a Class 1 survey unit to allow it to be handled separately from the remaining embedded piping. The purpose of designating this section of pipe as a Class l was because of the residual activity and the need to perform remediation. A Class 2 buffer survey area was not designated because the density of survey points for embedded piping is independent of classification and is dictated by the RSLTP. Based on the levels of gross activity reported, the remaining, embedded piping was determined to be a Class 3 area as an indication that residual radioactivity was not detected during scopjng surveys.

Survey Unit Design Information:

Static measurement locations were collected every six inches of accessible piping as specified in the License Termination Plan. Scanning of the length of piping was not conducted due to the number of static measurements collected. Piping was surveyed in defined segments as shown in Table 1.

A total of 504 static measurements were collected in a total of 255 linear feet of embedded piping. This corresponds to a measurement collected on average every 6.07 inches of piping and is consistent with the guidance from the RSL TP for embedded piping. Data collected was compared directly to the DCGL for embedded piping of I 00,000 dpm. The instrumentation used for the survey along with the MDC values are listed in Table 2-1 Attachment 2.

1 FSS Embedded Piping F8300123

FINAL STATUS SURVEY F8300123 Survey Results:

A total of 504 direct measurements were made in F8300123. The results of the static measurements are summarized in Table 1. All of the static measurements were less than the DCGL of I 00,000 dpm. None of the measurements indicated areas of elevated activity or required grouting of the piping (>21 ,000 dpm).

Table 1, Static Measurement Results Length of Range of Section of Number of Pipe Run Measurements Embedded Piping Measurements (feet) (dpm)

DAW Bay to Sump 86 154 4,090- 7,168 DAW Staging Bay 40 87 3,819- 12,437 to DAW line Cell C-1 to Sump 6 11 6, 195 - 6,915 Truck Bay Trench 28 61 5,764 - 6,657 to Truck Bay Sump Truck Bay Sump to 16 34 1,100-1,659 Sump 4 inch Truck Bay Sump to 23 47 5,935 - 9,376 Sump 6 inch Cask Wash Down to 20 40 3,620 - 5,518 Surrip Expansion line from 36 70 4,880 - 6,700 Sump Table 2 contains the statistical summary of the static measurement data for the Embedded Piping.

Table 2, Gamma Summary Statistics Embedded Piping Mean 5,038 Median 5,097 Standard Deviation 1,355 Minimum 1,100 Maximum 12,437

• Count 504 2 FSS Embedded Pipe f8300123

FINAL STATUS SURVEY F8300123

.Survey Unit Data Assessment:

The survey design required a static measurement every six inches of accessible piping.

Based upon the estimated length of piping and the number of measurements collected, the FSS resulted in a measurement roughly every 6.07 inches. All measurements were less than the DCGL.

Survey Unit Investigations and Results:

No investigations were required for the direct 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 designated as a Class 3 survey area and surveyed in accordance with the RSL TP for embedded pipe. Measurements were collected every 6.07 inches on average per the RSLTP. However this did not affect the survey effectiveness as 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 the results of the scoping survey. The required number of direct measurements made met the requirement of Table 5-6 of the LTP. All of the static measurements were less than the DCGL. No investigations were required.

The static 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 F8300123 meets the release criteria of 10CFR20.1402.

3 FSS Embedded Pipe F8300123

Attachment 1 Maps February 9, 2017 Survey Unit F8300123

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Attachment 2 Instrumentation January 25, 2017 Survey Unit F8300123

Table 2-1. Survey Unit Instrumentation l\!leasu'rement IVlinimuJ11 Detectable Activity"* ,,I)etej::tor *Cal.il!.ra.ti~*n.

. <TY1fe. . *. lnstrurii~nt Type

~ ' * -

• I , * *

• • ..Efi'i~iencies *Thie Date~

Gamma Static Ludlum Model 398 dpm/100 cm2 0.791% 203481/201151 Measurement 2350-1 4/15/17 4 inch pipe Ludlum Model 44-15 7 Detector Gamma Static Ludlum Model 247 dpm/I 00 cm 2 0.511% 203482/010057 Measurement 2350-1 6/30/17 6 inch pipe Ludlum Model 44-159 Detector a Minimum detectable activities for the count rate instrumentation were calculated in accordance with NUREG-1507, "Minimum Detectable Concentrations with Typical Radiation Survey Instruments for Various Contaminants and Field Conditions" (U.S. NRC, 1997).

b Detectors are required to be calibrated once every 12 months. Calibration due date indicates the date by which the detector must be calibrated again.

cm2 = square centimeters cpm =counts per minute dpm =disintegrations per minute Pagel Att. 2 Instrumentation F8300123

Static Measurement MDA Gamma Survey Type 201151 Detector Number 4500 Background count rate (cpm) 1 Count Time (min) 0.791 Efficiency 100 Area of Detector (cm 2)

Constants 60 sec/min 2.54 cm/in Assumptions Background count time and sample count time are equivalent Calculate Static MDA Static MDA =3 + 4.65(Br

• t) 0*5/t

• E

• Af,oo (NUREG 1507)

Where: Br Background Countrate t Count Time (min)

E Efficiency A Area of detector (cm 2)

Static MDA 398 dpm/100 cm2 Page 2 Att. 2 Instrumentation F8300123

Gamma SuNey Type 10057 Detector Number 700 Background count rate (cpm) 1 Count Time (min) 0.511 Efficiency 100 Area of Detector (cm 2)

Constants 60 sec/min 2.54 cm/in Assumptions Background count time and sample count time are equivalent Calculate Static MDA Static MDA =3 + 4.65(Br

• t) 0*5/t

• E

• A/100 (NUREG 1507)

Where: Br Background Countrate t Count Time (min)

E Efficiency A Area of detector (cm 2)

Static MDA 247 dpm/100 cm 2 Page 3 Att. 2 Instrumentation F8300123

Attachment 3 Investigation January 25, 2017 Survey Unit F8300123 (none required)

Att. 3 Investigation F8300123

Attachment4 Data Assessment January 25, 2017 Survey Unit F8300123

200 Histogram for Gamm Static Activity (dpm) Embedded Pipe ctel~

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1134 ,,.., 3401 7936 11331! 12471 Page 1 Att. 4 Data Assessment F8300 123

ndivly Q..Q Plot for Gamma Static Activity (dpm) Embedded Pipe ti .. .(JS MeMaStY.:;8 Sd

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.J 0 Theoretical Quantiles (Standard Normal)

Page2 Att. 4 Data Assessment F8300123