ML17065A060

Rancho Seco Nuclear Generating Station - 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

Approved By: Rancho Seco Final Status Survey Summary Report January 25, 2017 IOSB Embedded Pipe Survey Unit F8300123 FSS Engineer 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 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 Section of Length of Number of Range of Embedded Piping Pipe Run Measurements 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 Maps February 9, 2017 Survey Unit F8300123 v-* .!_.-:.::' ;

• J DRAIN TRENC-t """ .*' LCWER TRU% -. . * ' ! Expansion Linc HOf TRU;..K RAMP I DRAIN INTERIM ONSITE STORAGE BUILDING (IQSB) .. . . ... SMUD :C.unr,.v Approwd by. Oeacrfption: Drown B. Dote: Approwl dot..: Rev No.: Page I r w = A-I A-2 A-".J ! I : j 1l I! II I', i I/ ll *i : I, () Att. 1 Maps *(' h./ \:IN TRENC-H 5rdlt.'.111liP.1.

• fl. ?.>=-= r D 8300123 Instrumentation January 25, 2017 Survey Unit F8300123 l\!leasu'rement . <TY1fe. . Gamma Static Measurement 4 inch pipe Gamma Static Measurement 6 inch pipe Table 2-1. Survey Unit Instrumentation *. Type ' * -* I , *

• Ludlum Model 2350-1 Ludlum Model 44-15 7 Detector Ludlum Model 2350-1 Ludlum Model 44-159 Detector IVlinimuJ11 Detectable Activity"* ,,I)etej::tor ** . 398 dpm/100 cm2 0.791% 247 dpm/I 00 cm2 0.511% *Thie 203481/201151 4/15/17 203482/010057 6/30/17 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 Survey Type Gamma 201151 4500 1 0.791 100 Detector Number Background count rate (cpm) Count Time (min) Efficiency Area of Detector ( cm2) 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 ( cm2) Static MDA 398 dpm/100 cm2 Page 2 Att. 2 Instrumentation F8300123 SuNey Type Gamma 10057 700 1 0.511 100 Detector Number Background count rate (cpm) Count Time (min) Efficiency Area of Detector (cm2) 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 ( cm2) Static MDA 247 dpm/100 cm2 Page 3 Att. 2 Instrumentation F8300123 Att. 3 Investigation Attachment 3 Investigation January 25, 2017 Survey Unit F8300123 (none required) F8300123 Attachment4 Data Assessment January 25, 2017 Survey Unit F8300123

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200 Histogram for Gamm Static Activity (dpm) Embedded Pipe ,,. Minm.rn 1.1)99.l<l 190 12..437 42 SD 1.:Jnn s*-0.81 '"' Kutaris :U.f 17\) I '"' I (;!lM-5.(157&1 8Mo<ian 5J51.0? 9Noml<'llO..:ttb.lli-Jn I Olen BS.: 150 I I 0Mae0n:. 1'1) I 1ll I " I 110 ) ( ,oo .;; 90 "' Ill 60 "' "' ll '" 10 ___ o __ 1134 ,,.., 3401 7936 11331! 12471 Page 1 Att. 4 Data Assessment F8300123 Q..Q Plot for Gamma Static Activity (dpm) Embedded Pipe M.W JO))) ------/-... ........... ___........ .J 0 Theoretical Quantiles (Standard Normal) Page2 Att. 4 Data Assessment ......... .. -* . . F8300123 ndivly ti .. .(JS MeMaStY.:;8 Sd

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