ML090990731

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Final Status Survey Summary Report for January 19, 2009, Fuel Storage Building (+) 40 El. Floor, Survey Unit F8121001
ML090990731
Person / Time
Site: Rancho Seco
Issue date: 01/20/2009
From: Donna Anderson
Sacramento Municipal Utility District (SMUD)
To:
NRC/FSME
Shared Package
ML090830613 List: ... further results
References
DPG 09-097
Download: ML090990731 (30)
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Rancho Seco Final Status Survey Summary Report January 19, 2009 Fuel Storage Building (+) 40' El. Floor Survey Unit F8121001 Prepared By:

FSS Engineer Date:

Reviewed By:

\\-Date:

I 1-1V' 0 Lead FSS Engineer Approved By:

(f e I Dismantlement Date:

2 -6 7

Radiological

FINAL STATUS SURVEY,

SUMMARY

REPORT Survey Unit:

F8121001, Fuel Storage Building (+) 40' El. Floor Survey Unit

Description:

Operating History: The reinforced concrete structure containedthe spent fuel pool and supporting systems. The building contained three main elevations including the pool.

Residual radioactive material was known to be present on all levels of the interior of the building. Operating records and the HSA document several events with the potential for a release of radioactivity inside this structure. Three documented instances of contamination through the common fuel building/turbine building wall were noted.

Site Characterization: Direct measurements were made of each of the interior elevation surfaces as well as the exterior surfaces of the structure. These measurements confirmed the presence of plant-derived radionuclides. Direct measurements on the pool elevation showed a mean gross activity level of 16,900,000 dpm/100 cm2 and a maximum value of 200,000,000 dpm/100 cm2. Direct measurements on the +40' elevation showed a mean gross activity level of 5,942 dpm/100 cm2 and a maximum value of 19,357 dpm/100 cm 2.

Direct measurements on the building exterior showed a mean gross activity level of 1,408 dpm/100 cm 2 and a maximum value of 21,600 dpm/100 cm 2. Based on the classification procedure (DSIP-0020) and levels of gross activity reported, the interior of the spent fuel building was determined to be a Class 1, 2 area and the exterior was a Class 2, 3.

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 272 m2 were scanned for 100% coverage. Samples of removable contamination were collected at each direct measurement location. 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 9 FSS Summary Report F8121001

Table 1. Survey Unit Design Parameters Survey Design Value Comment Parameter Survey Area:

F812 Survey Unit:

Class:

SU Area (m2):

Evaluator:

DCGL (dpm/100 cm2):

Area Factor:

Design DCGLemc (dpm/100 cm 2):

LBGR (dpm/100 cm2):

Design Sigma (dpm/100 cm2):

Type I Error:

Type II Error:

Predominant Nuclide:

Sample Area (m2):

Scan Area (in2):

Scan Coverage (%):

Zl-, :

Sign P:

Calculated Relative Shift:

Relative Shift Used:

N-Value:

Design N-Value + 20%:

Design Min Samples N:

Grid Spacing L:

1001 1

272 D. Anderson 43,000 3.6 154,800 21,500 4,631 0.05 0.05 Cs-137 6.97 272 100%

1.645 1.645 0.99865 4.6 3

11 14 39 2.6 Fuel Storage Building (+)

40' El. Floor Structure Surface LTP Table 5-4 Gross Activity DCGL Class 1 Class I Default = 50% DCGL Class 1 Class I Uses 3.0 if Relative Shift is

>3 NUREG-1575 Table 5-5 Class I Class 1 Page 3 of 9 FSS Summary Report F8121001

Survey Results:

A total of 41 direct measurements were made in F8121001. The results including mean, median, standard deviation and range are shown in Table 2. All direct measurements were less than the DCGL. One of the scan measurements indicated an. area of elevated activity. The gamma scan activity ranged from < 1,080 dpm/100 cm 2 Co-60 and < 1,310 dpm/100 cm 2 to 9,366 dpm/100 cm 2 Cs-137., Beta scan activity ranged from 1,633 to 72,374 dpm/100 cm', based on a surveyor efficiency of 0.5 and no background subtracted. Samples for removable surface 'activity were all less than 10% of the DCGL as shown in Table 3. Removable surface activity samples were counted for alpha activity and none was detected at the MDC shown in Table 2-1 of Attachment 2.

Page 4 of 9 FSS Summary Report F8121001

Table 2. Direct Measurement Results Measurement ID Gross Activit (dpm/100 cm F8121001 -CO001 BD F8121001 -CO002BD F8121001 -CO003BD F8121001-CO004BD F8121001-CO005BD F8121001 -CO006BD F8121001 -CO007BD F8121001 -CO008BD F8121001 -CO009BD F8121001-COOIOBD F8121001-CO011BD F8121001-Co012BD F8121001--Co013BD F8121001 -CO014BD F8121001--Co015BD F8121001-CO016BD F8121001-Co017BD F8121001--Co018BD F8121001--Co019BD F8121001 -CO02OBD F8121001 -C0021 BD F8121001-CO022BD F8121001 -CO023BD F8121001-CO024BD F8121001 -CO025BD F8121001 -CO026BD F8121001 -CO027BD F8121001-CO028BD F8121001-CO029BD F8121001 -CO03OBD F8121001 -CO031BD F8121001 -CO032BD F8121001 -CO033BD F8121001-CO034BD F8121001-CO035BD F8121001-CO036BD F8121001-CO037BD F8121001-CO038BD F8121001-CO039BD F8121 001 -CO04OBD F8121001 -C0041 BD Mean:

Median:

Standard Deviation:

Range:

2,293 2,075 1,961 1,966 2,355 2,033 2,033 2,090 3,019 1,873 1,914 6,603 2,028 2,173 1,624 2,262 1,764 1,971 1,914 2,039 2,998 2,811 2,215 2,718 2,469 2,173 2,563 2,594 2,578 2,168 2,578 1,639 2,739 4,088 2,516 2,282 2,179 2,007 2,194 3,636 4,228 2,472 2,194 874 1,624 - 6,603 Page 5 of 9 FSS Summary Report F8121001

Table 3. Removable Surface Activity Results Measurement ID Surface Beta Activity (dpm/100 cm2)

F8121001 C0001 SM F8121001 C0002SM F8121001 C0003SM F8121001 CO004SM F8121001 CO005SM F8121001CO006SM F8121001 CO007SM F8121001 CO008SM F8121001 CO009SM F8121001 Co010SM F8121 001 C0011SM F8121001 Co012SM F8121001 Co013SM F8121001 CO014SM F8121001Co015SM F8121001 Co016SM F8121001CO017SM F8121001 CO018SM F8121001 Co019SM F8121001 CO020SM F8121001 C0021SM F8121001 C0022SM F8121 001 C0023SM F8121001 C0024SM F8121001 C0025SM F8121001 C0026SM F8121001 C0027SM F8121 001 C0028SM F8121001 C0029SM F8121001 CO030SM F8121001 C0031 SM F8121001 CO032SM F8121001CO033SM F8121001 C0034SM F81 21001 C0035SM F8121001 C0036SM F8121001 C0037SM F8121001 CO038SM F8121001 C0039SM F8121001 CO040SM F8121001 C0041 SM Mean:

Median:

Standard Deviation:

Range:

1.64 4.22 5.51 4.22 8.09 17.13 8.09 13.26 1.64 18.42 5.51 1.64 18.42 17.13 6.8 10.68 13.26

-2.24 9.38 1.64 30.05 8.09 27.46 4.22 9.38 2.93 21.01 23.59 0.34 5.51 2.93 9.38 10.68 6.8 14.55 11.97 1.64 13.26

-0.95 6.8 0.34 9.13 8.09 7.73

-2.24 to 30.05 Page 6 of 9 FSS Summary Report F812 1001

Survey Unit Data Assessment:

The survey design required 41 direct measurements for the Sign Test. The critical value and the results of the Sign Test are presented in Table 4. 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 7 of 9 FSS Summary Report F8121001

Table 4. Data Assessment Results Survey Results Parameter Value Comment Material Background Used (dpm/l00 cm 2):

N/A Ambient Background Used (dpm/100 cm 2):

N/A Average Ambient BKG = 0 Actual Direct Measurements (N):

41 Median (dpm/100 cm 2):

2,194 Mean (dpm/100 cm2):

2,472 Direct Measurement Standard Deviation 874 (dpm/100 cm2):

Total Standard Deviation (dpm/I00 cm2):

874 Based on samples and backgrounds.

Maximum (dpm/I00 cm2):

6,603 Material Type:

N/A Background Subtract Not.

Applied Sign Test Final N Value:

41 S+ Value:

41 Critical Value:

26 Sufficient Samples Collected:

Yes Maximum Value < DCGL:

Yes Median Value < DCGL:

Yes Mean Value < DCGL:

Yes Maximum Value < DCGLemc:

Yes Class 1 Total Standard Deviation <= Sigma:

Yes Pass the Sign Test?

Yes Reject the Null Hypothesis?

Yes Does the Survey Unit Pass All Criteria?

Yes Page 8 of 9 FSS Summary Report F8121001

Survey Unit Investigations and Results:

One investigation (juncture scan 11) was required for the scan measurements and the results are reported in Attachment 3. The EMC unity rule was not exceeded as shown in Table 3-1.

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 and the EMC criterion has been met), the ALARA criterion has been met.

Changes in Initial Survey Unit Assumptions:

The survey unit was designed as a Class 1 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. One potential area of elevated activity was detected and evaluated as shown in Attachment 3. Therefore the EMC criterion was met.

==

Conclusion:==

The FSS of this survey unit was properly designed as a Class 1 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. No direct measurements exceeded the DCGL of 43,000 dpm!100 cm2 and none of the removable surface activity measurements exceeded 10% of the DCGL. One investigation was 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 F8121001 meets the release criteria of 10CFR20.1402.

Page 9 of 9 FSS Summary Report F812 1001

Attachment I Maps January 19, 2009 Survey Unit F8121001

,V 00 0) 2 112 ft. - 34.1 m 0

1 2

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Distance in Meters Map F8121001-1, Fuel Storage Building +40' El. Floor Area Estimate: 272 sq. meters Location of Fuel Storage Building at Rancho Seco site

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4 Distance in Meters Map F8121001-2, Fuel Storage Building +40' El. Floor Random Start Location

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1 0 1 2 3 4 Distance in Meters Map F8121001-3, Fuel Storage Building +40' El. Floor Beta Direct Measurements F81210001 C0001BD to F81210001 C0041BD 2.64 meter grid

0 00 C) 2 N

1 2

3 4

Distance in Meters Map F8121001-4, Fuel Storage Building +40' El. Floor Beta Scan Measurements F81210001C0243BS to F81210001C0244BS and F81210001C0256BS to F81210001C0307BS

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Distance in Meters Map F8121001-5, Fuel Storage Building +40' El. Floor ISOCS Gamma Scan Measurements F8121001COOO1GS to F8121001C0028GS 12.57 sq. meter field of view

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0 1

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4 Distance in Meters Map F8121001-6, Fuel Storage Building +40' El. Floor ISOCS Gamma Scan Measurements F8121001C0031GS to F8121001C0047GS 7.1 sq. meter field of view

00 00 N -- ý 0

1 2

3 4

Distance in Meters Map F8121001-7, Fuel Storage Building +40' El. Floor Juncture Scan Measurements F81210001CO007JS to F81210001CO011JS and F81210001C0044JS to F81210001C0050JS

00 CI) 2r N

0 1

2 3

Distance in Meters 4

Map F8121001-8, Fuel Storage Building +40' El. Floor Investigation Measurement X8121001 C0001 BD Penetration Scan Measurements F8121001POOO1BS to F8121001POO1OBS

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Pulley Pulley Shaft Shaft

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4 Distance in Meters Map F8121001-9, Fuel Storage Building +40' El. Floor Location of Pulley Shafts

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N Map F8121001-10, Fuel Storage Building +40' El. Floor Location of Pulley Shafts Page I1I of 12 Att. 1 Maps F8121 001

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Distance in Meters Map V8121001-1, Fuel Storage Building +40' El. Floor Verification Beta Scan Measurements V81210001C0001BS to V81210001C0068BS Instrumentation January 19, 2009 Survey Unit F8121001

Table 2-1. Survey Unit Instrumentation Instrument Detector MDC Static MDC Scan Model; Serial No.

Model; Serial No.

(dpm/100 cm2 )

(dpm/100 cm2 )

M2350; 142499 43-37B; 148502 198 616 M2350; 180733 43-94B; 148620' 590 1,030 M2350; 180733 43-94B; 1486202 1,610 2,800 M2350; 180733 43-94B; 148620' 350 610 M2350; 180733 43-94B; 148620' 950 1,660 M2350; 203486 43-68B; 161400 433ý 1,033.

M2350; 175834 43-68B; 148634 433 1,033 M2350; 175834 43-116-1B; 1906425 796 3,258 M2350; 175834 43-116-IB; 1906426 491 739 M2350; 175834 43-116-1B; 1906427

.472 1,930 Tennelec; 0401171 N/A 5.88 dpm a, N/A 11.71 dpm 1l-inch concrete pipe 22-inch concrete pipe 3 1-inch metal pipe 42-inch metal pipe 5Concrete surfaces 6Concrete junctures 7Metal surfaces Page 2 of 3 Att. 2 Instrumentation F812 1001

Table 2-2. Investigation Criteria and DCGL Value P a r.a m ete r V l e 2

(dpm/100 cm 2)

Investigation Criteria - Direct 154,800 Investigation Criteria - Scan 154,800 Investigation Criteria - Scan (ISOCS average activity - 12.6 63,300 Cs-137 sq. meter field of view)

Investigation Criteria - Scan (ISOCS average activity - 7.1 115,000 Cs-137 sq. meter field of view)

DCGLW' 43,000 DCGLEMC 154,800 Page 3 of 3 Att. 2 Instrumentation F812 1001 Investigation January 19, 2009 Survey Unit F8121001

Table 3-1 Survey Unit Investigation Grid Investigation Initial Value Investigation Elevated Area Investigation DCGLemc iResult DCGLenc Result Unity Level (cpm)

(cpm)

(cpm)

Area (m2)

Factor (dpm/lOOcm2)

Fraction 11JS 7,100 7,179 7,087 0.0116 1,116.5 48,009,355 82,073 0.002 Survey Unit Remainder DCGL=

SU Mean=

0.057 43,000 2,472 EMC Unity Sum 0.059 Page 2 of 2 Att. 3 Investigation F8121 001 Data Assessment January 19, 2009 Survey Unit F8121001

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4-7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

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20 40 60 Percentile 80 100 Direct Measurements (dpm/100cm2)

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F8121001 Gross Activity Sample Results Scatter Plot DCGL = 43000 dpml00cm=1 7000

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