ML17065A071

Final Status Survey Summary Report, February 1, 2017, Iosb Hot Cell Pipe, Survey Unit F8300111

ML17065A071
Person / Time
Site:	Rancho Seco
Issue date:	02/01/2017
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: ML17065A071 (13)

Text

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'Rancho Seco Final Status Survey Summary Report February 1, 2017 IOSB Hot Cell Pipe Survey Unit ,F8300111 FSS Engineer Approved By:__,.,,,,...LJ4-....__........__,;~~-"~~~--"~....." ' - - Date:

Manager, Rancho Seco Assets

FINAL STATUS SURVEY F8300111 Survey Unit:

F8300111, Interim Onsite Storage Building (IOSB) Hot Cell Drain Pipe Survey Unit

Description:

Operating History: Designed primarily to store packaged radioactive waste containers safely, protected from the elements, and maintain radiological dose as low as reasonably achievable (ALARA), the hot cell possibly stored media of many types, including filters, resins, contaminated chemicals, DAW, activated reactor components, contaminated plant components and other contaminated items. Indications of a spill near the hot cell drain were found during the scoping surveys.

Site Characterization: Gamma static measurements were collected approximately every six inches through the various runs of embedded piping using a pipe detector. Beta static measurements were also collected in the drain trenches in each storage cell, the Truck Bay, and in the DAW Bay. Gamma static measurements in the Hot Cell drain exceeded the grouting action level of21,000 dpm/100 cm 2 but not the DCGL in the middle of the section of the vertical run from the hot cell floor to the 90° connection elbow leading to the sump.

The drain piping in the Hot Cell was designated as a Class l survey unit to distinguish this section of pipe from the remainder of the embedded piping.

Survey Unit Design Information:

Static measurement locations were collected approximately 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. Following the scoping survey, decontamination was performed in the vertical section of pipe leading from the hot cell to the 90° elbow, a distance of approximately four feet.

A total of 10 static measurements were collected in a total of 5.5 linear feet of the hot cell vertical section of embedded piping .. Data collected was compared directly to the DCGL for embedded piping of I 00,000 dpm/100 cm 2. The instrumentation used for the survey along with the MDC values are listed in Table 2-1 Attachment 2.

2 FSS Hot Cell Drain Pipe F830011 l

FINAL STATUS SURVEY F8300111 Survey Results:

A total of 10 direct measurements were made in F8300111 for the final status survey. Table 1 provides a listing of the direct measurement results. A statistical summary of the results of the static measurements are summarized in Ta'ble 2. All of the static measurements were less than the DCGL of 100,000 dpm/100 cm2* None of the scan measurements indicated areas of elevated activity or required grouting of the piping (>21,000 dpm/100 cm2).

Table 1, Gamma Static Measurements

• -*,*' .,

• . , *. *.***' *,[)epf~:fr9!]1 B§.f.< .*. ~ .. : .* > **  : .,

.<Number *.* ** S;impl~. #:.. . .  ; ::.~ '.:'.;C~.f!1~~1oor,: ,* * , *..._:.B..E!t~ ;(cprri), * :13~fa*(~pm}/:'.*.....,, *.

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• _ .* , *~.::*(fe'et) ,.,* , , ... : ;.:;: .* . . . .... .

• .. *.

• • '. *,

-;.** s.*_ ...

F8300011 M00001 5.0 10,897 13,776 2 F8300011 M00002 4.5 12,497 15,798 3 F8300011 M00003 4.0 12,524 15,833 4 F8300011 M00004 3.5 12,790 16,169 5 F8300011 M00005 3.0 12,414 15,694 6 F8300011 M00006 2.5 12,497 15,798 7 F8300011 M00007 2.0 12,875 16,276 8 F8300011 M00008 1.5 12,378 15,648 9 F8300011 M00009 1.0 13,224 16,718 10 F8300011M00010 0.5 11,844 14,973 Table 2, Static Measurement Results Gamma Static Hot Cell Drain Pipe Mean 15,669 Median 15,799 Standard Deviation 806 Minimum 13,776 Maximum 16,718 Count 10 Survey Unit Data Assessment:

The survey design was based upon guidance in the RSL TP and resulted in 10 static measurements. Following the guidance in the RSL TP, these values are compared directly to the DCGL of 100,000 dpm/100 cm2 .

3 PSS Hot Cell Drain Pipe F8300111

FINAL STATUS SURVEY F8300111 ALARA Statement:

As stated in Chapter 4 of the L TP, 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 in accordance with the RSLTP. The section of pipe was designated as a Class 1 survey area to distinguish it from the other embedded pipe as scoping measurements exceed the grout action level o 21,000 dpm/l 00 cm2 . No individual measurement exceeded the DCGL. No potential areas of elevated activity were detected.

==

Conclusion:==

The FSS of this survey unit was properly designed as a Class 1 survey based on the results of the scoping survey and the need to perform remediation. The sample density as specified in the RSL TP for embedded piping was met. 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 F8300111 meets the release criteria of I OCFR20. l 402.

4 FSS Hot Cell Drain Pipe F8300l l l

Attachment 1 Maps February 9, 2017 Survey Unit F8300111

• F8'100:fl1M0910. 14;973 <Jpm

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• F sjpo 111~0099 F8lPOlllM0008 15;648 dfm

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F83fJ)lllM0007 , 1~),.476 ..dgtn,.

{~$3UO't I JM'OQO,({ ---~5,:Z98. ~p~ .

-~J.5,694 ,*dpm 16,169 .dpm

___ ~ F830011Th1t0003 -15,833- dpm

~

• ~ :f8390.lllM0.002 1S;,Z9S . dpm~

• ~ F83.001l1MOQO_l

.. 13,z76-dp~

Page 1 Att. l Maps 8300111

Attachment 2 Instrumentation February 6, 2017 Survey Unit F8300111

Table 2-1. Survey Unit Instrumentation

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jVliniirium'.DetectabJe Actiy!tY"  :*,Detector Calibratio~

tiistrti nu!1.1t.T)'.p~* .* . .* '  ; ' *i; -

• ..Efficieilc.ies

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. , ": " . . . - .*

-~ ' , Due ,Dat~

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Gamma Static Ludlum Model 398 dpm/I 00 cm 2 0.791% 2034811201151 Measurement 2350-1 4/15/17 Ludlum Model 44-157 Detector

• 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.

cm 2 = square centimeters cpm =counts per minute dpm =disintegrations per minute Pagel Att. 2 Instrumentation F830011 l

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

• A/100 (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 F83001I1

Attachment 3 Investigation February 6, 2017 Survey Unit F8300111 (none required)

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Att. 3 Jnvestigation F83001 I l

Attachment 4 Data Assessment February 9, 2017 Survey Unit F8300111

. A ct iv~(~

Histogram for Gamma Scan Activity (dpm) Hot Cell Drain Pipe N~ ofV4iue'l 10

.

MiVn.m 1:J.77G.23 M81Cimo.n 16,71 8_001

,so...,.., ll>i13

.......

BM-

• 1'8 1 1' 15.668.n BM""" 15.798.SS

~Norrroa! C>UbtvM

~len Bn:

0 M01aD ~

13'"'9 14209

• 14709 15129 15550 15970 16:Bl Page 1 Att. 4 Data Assessment F8300111

\':,*<, Q-Q Plot for Gamma Static Activity (dpm) Hot Cell Drain Pipe /l.ctiYit1l<tiiil N .. 10 1-* MeM

• 156&9 I . Sd*806.1 J.

I ,_ Slopo*n5.1 loteicepl*l5Q)$

CooMMior~ A "0 ::JH;

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I! 160CJO 15500

• 1.0 -0.5 0.0 0.5 1.0 1.5 Theoretical Quantiles (Standard Normal)

Page2 Att. 4 Data Assessment F8300111