RA-05-035, Repsonse to NRC RAI on FSS Final Report No. 9A

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Repsonse to NRC RAI on FSS Final Report No. 9A
ML051890095
Person / Time
Site: Maine Yankee
Issue date: 06/28/2005
From: Feigenbaum T
Maine Yankee Atomic Power Co
To:
Document Control Desk, NRC/FSME
References
MN-05-032, RA-05-035
Download: ML051890095 (27)
v • d • e


Text

MaineYankee 321 OLD FERRY RD.

  • WISCASSET, ME 04578-4922 June 28, 2005 MN-05-032 RA-05-035 Proposed Change No. 218, Supplement 28 UNITED STATES NUCLEAR REGULATORY COMMISSION Attention: Document Control Desk Washington, DC 20555

References:

(1) License No. DPR-36 (Docket No. 50-309)

(2) Maine Yankee Letter to USNRC, MN-04-020, dated March 15, 2004, License Amendment Request: Release of Non-ISFSI Site Land, Proposed Change No. 218 (3) Maine Yankee Letter to USNRC, MN-05-020, dated May 5, 2005, Release of Non-ISFSI Site Land - FSS Final Report No. 9A, Proposed Change No.

218, Supplement 21 (4) USNRC Letter to Maine Yankee, dated June 23, 2005 Request for Additional Information (RAI) Regarding Final Status Survey (FSS)

Supplement No. 9A

Subject:

Response to NRC RAI on FSS Final Report No. 9A On March 15, 2004, Maine Yankee submitted a request for amendment (Reference No. 2) to the facility operating license (Reference No. 1) pursuant to 10 CFR 50.90 and in accordance with the NRC Approved License Termination Plan (LTP) for Maine Yankee, to indicate NRC's approval of the release of the Non-ISFSI site land from the jurisdiction of the license. In support of that request, Maine Yankee supplied the information required in LTP section 1.4.2 and 5.9.3. The land area associated with the license amendment request included the entire non-ISFSI portion of the site land. The dismantlement and survey information for the survey units is being submitted to the NRC in FSS Final Reports.

In Reference No. 3, Maine Yankee submitted FSS Final Report No. 9A. In Reference No. 4, USNRC requested additional information on technical information submitted in FSS Final Report No 9A. This additional information is provided in an attachment to this letter.

If you have any questions, please contact me.

Sincerely, Ted C. Feigpurum President Chief Executive Officer fd Y5 5 0 ~

UNITED STATES NUCLEAR REGULATORY COMMISSION Attention: Document Control Desk Page 2 of 2

Attachment:

Maine Yankee Response to NRC Request for Additional Information (RAI)

Regarding Final Status Survey (FSS) Final Report No. 9A cc: Mr. D. R. Lewis, Esq., Shaw Pittman Mr. C. Pray, State of Maine, Nuclear Safety Advisor Mr. P. J. Dostie, State of Maine, Division of Health Engineering Mr. D. Gillen, NRC Director, Division of Waste Management Mr. M. Rosenstein, USEPA Region I Mr. S. J. Collins, NRC Regional Administrator, Region I Mr. J. Buckley, NRC NMSS Project Manager, Decommissioning Mr. M. Roberts, NRC Region I Mr. R. Shadis, Friends of the Coast

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAT) Regarding Final Status Survey (FSS) Final Report No. 9A NRC RAI No. 1 - Attachment 1 Attachment 1, page 5 of 13, states, "Typically, afinalstatus survey is conductedon building basement surfaces beforefill materialis placed in the basement."

The MYLTP requiresthat all building basementssurfaces have afinal status survey (FSS) conductedto demonstratecompliance with the DCGLs and release requirements. Please confirm that all buildingbasement surfaces have hadFSS or identify the areasthat have not hadFSS performedpriorto havingfill materialplaced over the surfaces.

Maine Yankee Response:

LTP Section 5.2.3 states: "The soil below removed foundations in the RA and Industrial areas will undergo final survey prior to backfill." "The excavated foundation areas for any building or structure outside of the IA may not be surveyed prior to backfill."

In all cases, for buildings in the RA and Industrial area, building basement surfaces were subject to final status surveys prior to those surfaces being covered with backfill. In the case of the spray building, the lower basement areas were surveyed and backfilled prior to the completion of survey and backfill of the upper basement surfaces, eg. 12' floor elevation remnant. Thus all building basement surfaces within the RA and Industrial area have had FSS prior to having fill material placed over the surfaces.

For buildings outside the Industrial Area, typically, a final status survey was conducted before backfill even though it was not required. The basement of the Bailey Building was backfilled and FSS subsequently performed on the building footprint. This was appropriate since the building was located outside of the Industrial Area at the most remote location from the plant within the Class 3 area and characterization surveys did not detect any activity other than naturally occurring radioactive material in the basement.

NRC RAI No. 2 - Attachment 1 Attachment 1,page 6 of 13, Section 4.2.1, states, "the LTP Section 3.2.4 indicatedthat the fuel building would be demolished to 3 feet below grade...AII of the interveningwalls andfloors may be removed" and that, "The spentfuelpool liner would be removed due to known contamination levels. " This section concludes with the statement, "All demolition activities associatedwith the fuel buildinghave been completed."

The LTP states that some or all of the interveningwalls andfloors in the basement "may" be removed The FSS Report (FSSR) is not clear on what demolition work was actually completed Pleaseclarify which walls andfloors were removed and which remain in place.

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ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A Maine Yankee Response:

The spent fuel pool liner was removed from the pool and properly disposed. All of the intervening walls and floors were removed. Furthermore, much of the concrete floor and outer walls were also removed.

NRC RAI No. 3 - FR-0400-SU1 Please clarify the following issues concerningFR-0400-SUI:

NRC RAI No. 3A - FR-0400-SU1 - Concrete Surface Beta Measurements Consistent with the LTP, the survey unit design establishesa DCGLfor concrete surfaces of 18,000 dpm/J00 cm 2 gross beta activity, anda DCGLEAw of36,000 dpm/100 cm2 gross beta activity. LTP Section 6.7.2 requiresthat, "The DCGLfor contaminatedconcrete is expressed as dpm/J00 cm 2 detectable beta. Thisform was requiredbecause thefinal survey will be performed using gross beta measurements."

NRC RAI No. 3A - FR-0400-SU1 - First Bullet However, as discussedin Section C, gamma scans were performed using an investigation level of 1,800,000 dpm/m 2 gamma surveys using ISOCS measurements with afieldof view of 12.6 in2 .

The ISOCS averagesthe gamma activity over the entire 12.6 m 2field of view. The survey unit results equate the 12.6 W2 field of view to an average of 1,800,000 dpm/m2 gamma activity and then averages the 1,800,000 dpm/m2 to equate to the 18,000 dpm/100 cm2 beta DCGL. Please justify the use of ISOCS gamma scans to meet the FSS beta scan requirementsofLTP Section

6. 7.2. In addition, demonstrate that an ISOCS gamma scan investigationlevel of 1,800,000 dpn/m2 can be used to detect the gross beta DCGL and DCGLE I, Maine Yankee Response:

The basement fill model for concrete surface activity is an inventory based DCGL. The dose delivered to the resident farmer is a function of the total activity released to the fill material and drinking or irrigation water upon being desorbed from the concrete. The Total DCGL is 29,000 dpm/100 cm2 as shown in Table 6-13 with the Gross Beta DCGL being 18,000 dpm/l00 cm2.

The primary beta emitters, accounting for approximately 94% of the beta detectable activity, in the nuclide mixture are Co-60, Cs-134 and Cs-137 as shown in Table 5-3a of the LTP. These same nuclides are easily detectable by gamma spectroscopy. The LTP clearly stated in section 5.5.1 .a Structures that volumetric measurements would be used "when necessary". "Volumetric concrete samples will be analyzed by gamma spectroscopy" and will be evaluated "by using the radionuclide specific results to derive the surface activity equivalent and determine compliance Page 2

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A using the unity rule." It should be noted that Table 64 of the LTP expresses the source term in units of both dpm and pCi with the resulting material concentration values for both soil and concrete presented in units of pCi/g. Thus the LTP clearly allows the surface DCGL specified in gross detectable beta to be measured by gamma spectroscopy.

Because ISOCS provides an average activity value, additional considerations have to be made when using it for scan measurements. An Investigation Level has to be established which represents the average ISOCS result which is equivalent to a small area of elevated activity. Soil measurements have been performed using an Investigation Level derived by analyzing spectra with a field of view (FOV) equal to the geometrical area seen by the detector for a given source to detector distance. For soil scans a distance of 3 m was used which gave a field of view of 28 in2 . The spectra were re-analyzed with the geometry revised to place the entire activity in a small area at the edge of the detector field of view. The ratio of results of the small area to the large area was then divided into the maximum allowed activity for a given small area (i.e., the DCGL^,c). The result was the "Investigation Level" or the analytical result for 28 m2 which would be equal to the response if the DCGLJmC activity were located within a small area at the edge of the detector field of view. For soil scans, the investigation criteria were 0.36 pCi/g for Co-60 and 1.0 pCilg for Cs-137 based on EMC values of 10.32 pCi/g and 28.68 pCi/g respectively.

A similar process was developed for ISOCS measurements taken on concrete surfaces. For concrete scans, the applicable DCGL is 18,000 dpm/100 cm2. The activity is assumed to be deposited on or near the surface of the concrete. According to the LTP, a 1 m2 area could have 50 times the DCGL or 900,000 dprn/1 00 cm2.

ISOCS scans of FA0400 concrete conservatively assumed a contamination depth of 5 cm,. The field of view was 12.6 m2 for a source to detector distance of 2 m. Applying the same process as that used for soil, results in an Investigation Level for Co-60, (the gamma-emitting radionuclide with the lowest MDA) of 153,000 dpm/1 00 cm2 for a 1 m2 area centered directly under the detector and 55,100 dpm/1 00 cm2 for a I m2 area located at the edge of the FOV. If a smaller elevated area (e.g., 100 cm2) is used, the Investigation Levels are 167,300 dpm/100 cm2 for an area of 100 cm2 located under the detector and 28,600 dpm/100 cm2 located at the edge of the FOV. The actual investigation criterion used was the DCGL (18,000 dpm/100 cm2). See Appendix A for a further description of how these investigation levels were determined.

The maximum scan values reported for FA0400 were 5640 dpm/100 cm2 for Cs-i 37 (from an area that was subsequently remediated as a courtesy to the State of Maine) and 1198 dpm/I00 cm2 for Co-60. Both of these scan values are well below the required Investigation Levels. Thus it is clear that ISOCS is appropriate for performing concrete scans and that the scan results for FA0400, and other survey units with concrete remnants, were acceptable.

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ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A NRC RAI No. 3A - FR-0400-SUI - Second Bullet In Table 2-2, the ISOCS scan MDC ranges are listed with values ofup to 1480 dpm/100 cm.

These values appearto be the averages of the ISOCS 12.6 m2 field ofview measurements, the weighted average of 1 m 2 readingsand the average ofthe I m2 areasto 1 00 cm2 . It appearsthat the 1480 dpm/JOOcmn is derivedfrom the total ISOCS measurement of 1,864,800 dpm/m2 in the 12.6 in2 view. Pleasejustify the ISOCS scan MDC ranges.

Maine Yankee Response:

The design MDC was 2500 dpm/100 cm2 or 14% of the DCGL. The actual MDC values reported in Table 2-2 of the Release Record were based on the ISOCS analyses MDA values, in a manner similar to the MDA's reported from laboratory GeLi detector analysis. These values are reported from the ISOCS analyses in units of dpm/m 2 which are simply divided by 100 *

(100cm 2/m2 ) to convert to units of dpm/1OOm 2 . It is not derived by dividing an ISOCS measurement by the field of view. The 227 to 1480 dpm/100 cm values were the minimum and maximum MDAs for detector #7607 and were equivalent to MDAs of approximately 0.09 to 0.6 pCi/g for Cs-137 in concrete. The Investigation Level of 18,000 dpm/100 cm2 was less than the DCGLJmC and the scan MDC was less than the Investigation Level which assured adequate sensitivity for the scan measurements.

NRC RAI No. 3A - FR-0400-SU1 - Third Bullet Table 3-1, Sample Location S081 lists the post remediationISOCS scan at 2 m as 274,570 dpm/m2 for Cs-137 and 74,019 dpm/,n for Co-60. Since this datawas from an ISOCS scan averagedover an areaof at least I mn2 it appearsthe actualresidualactivity in S081 could exceed both the DCGL and the DCGLE,,J, The staff also notes thatMaine Yankee has not notified the NRC of the proposeduse of the ISOCSfor measurements of concrete surfaces, and the derivation of the new DCGL based on the average gamma activity requiresNRC approvalin accordancewith LTP Section 1.4. Pleaseprovide thejustficationfor using ISOCS gamma measurements to demonstrate compliance with the concretegross beta activity DCGL and DCGLEufc approved in the LTP.

Maine Yankee Response:

The activity levels of 274,570 dpm/m 2 (or 2745.7 dpm/100 cm2) for Cs-137 and 74,019 dpm/m 2 (or 740 dpmi/100 cm2) for Co-60 are the average results for a field of view of 12.6 m2 . The measurements were made with an Investigation Level of 18,000 dpm/1 00 cm2 in order to ensure the DCGLEmC for a small elevated area would not be exceeded.

The Forebay Technical Basis Document (Reference No. 66) previously submitted to the NRC discussed the use of ISOCS for measurements of the "Floor of the Forebay and Remediated Page 4

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A Concrete Structures Underwater". Included within this Technical Basis Document was the use of ISOCS on concrete and ledge surfaces which were modeled in the same manner as the building basement surfaces with a similar DCGL. Furthermore, LTP Section 5.5.1.a allows the concrete surface gross detectable beta DCGL to be measured by gamma spectroscopy. This is technically appropriate for the Maine Yankee BOP contaminated concrete nuclide fraction since the detectable beta fraction and the gamma fraction of the nuclide fraction are the same. The justification of the use of ISOCS for the detection of the concrete DCGL and DCGLzmC was also previously discussed in the response to 3A, First Bullet. Thus, Maine Yankee previously fulfilled the 30 day notice and review commitment specified in LTP 1.4 by submittal of the ISOCS Technical Basis Document in Reference Nos. 66 and 68, applying this pre-reviewed technology to surfaces which were already allowed by the LTP to be measured by gamma spectroscopy.

NRC RAI No. 3A - FR-0400-SUI - Fourth Bullet Table 3-1, for sample locations S040, S045 and S081, the SSPA-3 results are 143,000, 143,000, and 52,400 cpm gamma, respectively. Although the measurement areasare not provided, it appearsthat these activitiescould exceed the DCGL and DCGLEwJ Pleasedemonstrate that these gamma results do not exceed the gross beta DCGL andDCGLElC Maine Yankee Response:

The table below shows the size of the elevated areas and the post remediation "as left" SPA 3 activity and the ISOCS activity compared to the EMC values. The elevated area for locations S040 and S045 appeared to be the same area as they were adjacent scan grids with the elevated activity found in the overlapping field of view. It should be noted that the readings for S081 included some soil activity from which 3 discrete particles were removed.

Location Initial SPA As-Left SPA Area DCGLmC As Left ISOCS (cm2) (dpm/100 cm2 ) (dpm/100 cm2 )

Co-60 Cs-137 S040 143,000 c/m 10,900 c/m 342 2.6E7 <931 652 S045 143,000 c/m 10,900 c/m 342 2.6E7 <958 <1040 S081 52,400 c/m 13,400 c/rm 408 2.2E7 640 2746 NRC RAI No. 3B - FR-0400-SU1 The survey design assumes all measurements are on concrete surfaces, andall results, including the soils, are comparedwith the concrete surface DCGL. The soil measurements were converted Page 5

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A from volumetric to arearesults andreportedas a comparison to the concrete surface DCGL.

Given the presence ofsoils, it appearsthat the survey design should have included instructions for soil samples and measurements. Pleaseexplain why soil measurements were not compared with the soil specific activityDCGLs listed in LTP Table 6.11. In addition,pleaseprovide other survey parameters, such as scan MDCs, to demonstratecompliance with the LTP.

Maine Yankee Response:

The Survey Unit designation is actually FA0400 which indicates a structure survey using the basement fill DCGL. The survey unit consisted of the excavated walls and floor of the Fuel Building. Much of the walls and floor were completely removed. However, since the dose model was approved with the fuel building basement modeled as part of the basement fill scenario, Maine Yankee applied the basement fill DCGL. Thus, all of the activity values were converted to units of dpm/100 cm2. This is appropriate because the DCGL is inventory based and, as stated in the LTP section 6.7.2, the DCGL results in fill concentrations less than soil DCGL NRC RAI No. 3C - FR-0400-SU1 Pleaseprovide gamma surveys or sample datathat demonstratesthat there is no contamination at depth in the concretefoundationremnants. The staffrequiresspecific clarificationof the following:

Maine Yankee Response:

See Appendix B and the table presented in the response to 3A, fourth bullet.

NRC RAI No. 3C - FR-0400-SU1 - First Bullet Table 3-1, lists SSPA-3 readingsof143,000 cpm, 143,000 cpm. and 52,400 cpm for sample locations S040. S045, and S081 respectively. These measurements exceed the 30,000 cpm limit forfixed contamination. The recorddoes not include an explanationas to the presence ofcracks or crevices and no concrete sample results are providedthat demonstrate that remediation was completed Pleaseprovide this information.

Maine Yankee Response:

These locations were remediated and "as left" SPA-3 reading were less than 30 kcpm.Table 3-1 of the Release Record and the response to 3A, 4th bullet above, provide the "as left" activity values for the investigated locations.

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ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A NRC RAI No. 3C - FR-0400-SUI - Second Bullet Table 3-1, footnotes 1 and 2, "Total Beta" activity in units of dpm/1 00 cm2 ivas derivedfor Sample Location S136from a concrete sample that was analyzedby a gamma spectroscopy. It is not clearwhy the total beta activity was determinedfrom gamma spectroscopy measurements since LTP Section 5.5.1 (a) specifies that concrete sampling will be performed "if the efficiency or uncertainty of beta measurements are too high."

Maine Yankee Response:

The LTP clearly stated in section 5.5.l.a Structures that volumetric measurements would be used "when necessary" and would be evaluated "by using the radionuclide specific results to derive the surface activity equivalent and determine compliance using the unity rule." Beta measurement efficience and uncertainty issues one of the possible reasons that concrete sampling "may be necessary." In the case of the Fuel Building the removal of the concrete walls and floor left a surface which necessitated volumetric sampling.

NRC RAI No. 3D - FR-0400-SU1 In CR-05-023, it is stated that the State of Mainefound residualradioactivityin a concrete crack using a different survey method The NRC Staff does not believe that the use of different equipment is a valid reasonfor not detecting residualcontaminationin excess of the 30,000 cpm gamma limit. Therefore. Maine Yankee should re-evaluate the conclusionsand corrective actions. This issue will be referredto RegionalInspector.

Maine Yankee Response:

Maine Yankee conducted scans of concrete surfaces in survey unit FA0400-01 and found no indication at or above the Investigation Criterion. The State of Maine used a Nal detector contact measurement with a very slow scan speed to locate the small elevated area which later was investigated and reported in CR 05-023. The elevated area was reported in Table 3-1 even though it had been remediated. Different scan techniques have different sensitivities which was the point of the statement in the CR. The residual radioactivity found by the State of Maine would have been acceptable to leave. This is demonstrated by the fact that the pre-remediation activity was included in Table 3-1 resulting passing the EMC Unity Rule. However, the residual radioactivity was removed as a courtesy to the State of Maine.

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ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A NRC RAI No. 4 - FR-0111-SU15 and SU16 FR-O 11-SU15 and SU16 -please clarify the meaning of "media appropriategeometries' and provide ajustificationof the geometries employed and the media measurementsfor these survey units.

Maine Yankee Response:

"Media appropriate geometries" refers to the use of specific geometries for each of the various materials such as soil, concrete and ledge which are encountered in the survey unit. There were no new geometries used.

NRC RAI No. 5 - FR-0111-SU16 FR-0111-SU16 -pleaseprovide a descriptionof the concrete surfaces, the beta surface survey data, and the gamma surveys or sample datathat demonstrates there is no contaminationat depth in accordancewith L TP Section 5.5.1 for the concrete surface remnants buried.

Maine Yankee Response:

Concrete remnants in FR-O I 11 Survey Unit 16 included an exposed portion of the PAB's north exterior wall, a small segment of the foundation ring for TK-13B (BWST), a portion of exposed duct bank where it passed through the tank foundation, and the reserve station transformer's (X-14/16) support foundation and impoundment basin. The exposed area of concrete on the side of the PAB was approximately 4m2. The location of this area is shown of FSS map FROIl 1-6e.

Similarly, the exposed area of the tank foundation/duct bank was approximately 27m2 and was located near the survey unit's southwest corner. The tank was located near the PAB's north wall, within an above grade concrete impoundment area. The PAB's north wall was a part of the impoundment structure. The BWST was located within the restricted area during plant operation. During decommissioning, the PAB walls, BWST foundations, and impoundment walls were demolished to a minimum of 3 ft. below grade.

The foundation and subgrade impoundment basin for the transformers consisted of 8" thick concrete walls with a footprint of 57.33 ft. x 28.33 ft. (approximately 150 n2). The original depth of the basin varied from approximately 3 R. to 7 ft. During plant operations the impoundment basin was filled with crushed stone and was located outside the original restricted area. The crushed stone was removed and the structure was demolished to a minimum of 3 ft.

below grade.

Refer to the Appendix C remediation surveys for the gamma scans that demonstrate there is no contamination at depth.

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ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAT) Regarding Final Status Survey (FSS) Final Report No. 9A NRC RAI No. 6 - FR-2600-SU1 FR-2600-SU), Section B, states, "Therefore, as discussedpreviously with the NRC, the measurements obtained in this survey unit will be taken on the interiorsurfaces of the MHand HH vaults."

The staffwould like to clarify that the discussion referenced by Maine Yankee wasfocused on the acceptability of surveying the cables as they were removedfrom the electric bank conduits in order to justify not surveying the miles of conduits. The Staff agreedthat the surveys of the cables would be representativeofany residualradioactivityin the conduits and there would be no need to survey the conduits other than the accesspoints, Maine Yankee andNRC staffs did not discuss the surveys to be taken in manholes or handholes.

Maine Yankee Response:

Maine Yankee discussed its plans for FSS of the Duct Banks with the NRC in a Telephone Conference conducted on October 14, 2004. The FSS of the Duct Banks was modeled after the FSS description of the Class 3 storm drains in LTP Appendix 5A. Maine Yankee presented its FSS plan which included the following elements: The manhole was to be opened and the manhole interior surfaces were to be subjected to direct measurements using gas-filled detectors and scans. Sediment/gravel in the manhole was to be sampled and analyzed volumetrically. The presence of pant-derived nuclides was to be evaluated.

At the conclusion of the call, the NMSS staff reviewer suggested that we also take smear measurements on cables as they are removed from the electrical bank conduits. Therefore, even though many of the cables had already been removed from the conduits, Maine Yankee made provision to collect smear measurements from some cables being removed from the conduits.

However, it was never the intention that the smear measurements would constitute the FSS data set.

NRC RAI No. 7 - FR-2600-SU1 & CR-05-012 FR-2600-SUJ references Condition Report CR05-012, "PotentialContaminationofFR2600 Survey Unit 1, " that documents the discovery of contaminationaroundManhole I (MH-1).

Please clarify thefollowing issues concerningFR2600 SU] and CR05-012:

NRC RAI No. 7A - FR-2600-SU1 & CR-05-012 The CR draws the conclusion that any potentialcontaminationwasfrom FROIJI SU16 which contains Class 1 soils above the manway. The CR makes the assumption that the contamination is evenly distributedin the 3 inch depth ofsoil and water on thefloor and equates the soil specific activity to areal concrete surface activity and compares the concrete surface activity Page 9

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A with the Class 3 DCGL of (50% of9800 dpm/100 cm 2) 4900 dpm/100 cm 2 concretepipe DCGL insteadof the LTP approved soil DCGL. Attached to the CR, is an ISOCS reportdated March 17,2005, that derives the floor activity of 1750 dpm/1 00cm2 (Cs-13 7)from an ISOCS scan with a 9.29 m2 field ofview and a weighted average of 174,980 dpmlm 2 for Cs-137 and 113,350 dpm/m 2 for Co-60 and a total activity of the tvo nuclides of 288,530 dpm/100 m2 . Pleasejustify the comparison ofthe contaminatedsoil in the pipe with the concretepipe DCGL insteadof the soil DCGL. In addition, please clarify how thefloor activity was derived as well as the ability to detect 4900 dpm/100 cm2 (ie 50% of the DCGL).

Maine Yankee Response:

The DCGL for the Duct Banks was a surface DCGL of 9800 dpm/I00 cm2 , the same DCGL as that used for buried pipe. The Investigation Level for the survey unit was established at 50% of the DCGL or 4900 dpmn/100 cm2.

Contrary to the NRC statement in the RAI above, the CR does not make the assumption that the contamination is evenly distributed in the 3 inch depth of soil and water on the floor and and it does not equate the soil specific activity to areal concrete surface activity. The CR states the following: "Since the manhole contained an estimated 3 inches of water and debris, an evaluation was performed to determine the attenuation effects of 3 inches of water on the reported results, assuming all of the activity was evenly distributed on the floor of the manhole", not in the 3 inch depth of soil and water on the floor. The ISOCS scans of the manholes were designed to determine activity on the concrete surfaces of the duct banks shielded by the reported depth of sand and/or water. The material inside the manholes was shielding the potential surface activity of the concrete and had to be accounted for in the geometry. Thus, it was appropriate to compare the attenuated surface activity to the buried pipe surface DCGL.

The ISOCS report dated March 7, 2005, reports activity of 174,980 dpmlm 2 for Cs-137 and 113,350 dpm/m 2 for Co-60. This can be converted to units of dpm/100 cm2 by dividing by 100

  • 100cm2 /m2 The design scan MDC was set at 10%of the DCGL or 980 dpm/100 cm2 As reported in Table 2-2 of the Release Record, the scan MDC achieved was between 67 and 136 dpm/100 cm2 ,

depending on which detector was used.

NRC RAI No. 7B - FR-2600-SU1 & CR-05-012 Section B. identifies Reference 6 (CR-05-012) as the document evaluatingthe broken top/vall and the missing hand hole. Please clarifrwhether the hand hole cover was removed or the entire vault with the hand hole was removed. If the entire vault was removed, pleaseprovide soil sample datato show that the soils underthe vault areasmet release requirements.

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ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A Maine Yankee Response:

The entire vault was removed. The post-removal soil excavation surface was FSS surveyed as part of FR-O111 Survey Unit No. 16.

NRC RAI No. 7C - FR-2600-SU1 & CR-05-012 FA 2600-SUI, Section C, states that gamma scans were performed in 19 vaults at -50% ofthe' DCGL of 4430 dpm/100 cm 2 for Cs-137, and 470 dm 100cm2for Co-60. MYLTP Section 6.7.2 requiresthat, "The DCGLfor contaminatedconcrete is expressedas dpm/100 cm 2 detectable beta. Thisform was requiredbecause thefinal survey will be performed usinggross beta measurements. " Since the ISOCS averages the gamma activity over thefield of view and provides a weighted activity average over 1 m2, the measurement technique employed may exceed the 50% ofthe DCGL when the average activity converted to an area100 cm2 . In CR05-012, ISOCS scans ofMH-1, activities in dpm/m2 are converted to dpm/100 cm2 and it is implied that the surface activity is below the DCGL of 9800 dpm/100 cm2 and50% of the DCGLfor a Class 3 area This approachappearsto be inconsistentwith the LTPfor surveying concrete surfaces. Pleaseexplain how the use of the ISOCS meets the LTP requirement to perform beta FSSs.

Further. the staff is concernedthat since the ISOCS averagesgamma activity over the areaof view, it may not be capable of detecting residualradioactivityin some areasin excess of50% of the DCGL. as well as the DCGL. The staffalso notes that Maine Yankee has not notified the NRC of the proposed use of the ISOCfor measurements of concrete surfaces. In addition, the derivation ofthe new DCGL (In units of dpm/m 2 ) based on the averagegamma activity requires NRC approval in accordancewith LTP Section 1.4 Maine Yankee Response:

The appropriate DCGL for Duct Banks and the use of ISOCS for concrete was described above in the previous responses (RAI No. 3). No new DCGL has been derived. The DCGLs cited are the same as those listed in the LTP, however, for convenience the DCGL has been expressed in units of dpm/m 2 instead of dpm/100 cm2 . In this case, however, the surface is in a Class 3 survey unit and subject to I to 10% scan coverage. The ISOCS scans covered 100% of the accessible surfaces (about 5% of the survey unit size).. The ISOCS scan measurements did not detect plant-derived activity in excess of the MDA's (Max 136 dpm/1Ocm2 ).

Page 11

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAT) Regarding Final Status Survey (FSS) Final Report No. 9A NRC RAI No. 8 - FR-2600-SU1 FA-2600-SUI. Section 5, states "The vaults generally make up the low pointsfor this survey area.As such, the MHs and HHs have the highestpotentialforcontainingresidualradioactivity in the duct bank conduits," It appearsthat all 14 direct measurements in Table 2, as shown on Maps FA 2600 1 a thru I k1arefrom the walls ofthe manholes andhandholes and not on floors where the highestpotentialforcontaminationexists. Please clarify how/why all direct measurements were taken on walls and not on the floors where the highestpotentialfor contaminationexists, andjustify how the collection of the data is consistent with L TP Sections 5.4.4 and 5.4.5 (d) and NUREG-1575.

Maine Yankee Response:

FR2600, SU-1 was a Class 3 survey. As such, the direct measurement locations were determined randomly as required by LTP sections 5.4.4 and 5.4.5(d) and NUREG-1575. The random assignment of locations initially placed two of fourteen direct measurement locations on the floor. The floor survey points had to be relocated due to water and sediment in the bottom of the manholes. Two additional direct locations also had to be moved due to physical obstructions.

The fourteen beta direct measurements were taken using the 43-68 gas proportional detector.

The mean beta direct value was 1632 dpm/100 cm2 with a maximum value of 2857 dpm/I00 cm 2 .

Twenty scan were made with ISOCS having a mean value of 115 dpm/100 cm2 Cs-137 and 96 dpm/100 cm2 Co-60. The maximum scan value was 136 dpmlOO cm2 Cs-137 and 104 dpm/100 cm2 Co-60.

NRC RAI No. 9 - FR-2600-SU1 FR-2600-SU1, Section C, indicatesthat an evaluation was performed to determine the attenuationeffects ofwater and sediment levels in the manholes rangingfrom0.5 to 1 inches in depth, and a worst case sediment depth of5 inches. However, in CR05-012, it is documented that the soil, debris, and water were removedfrom the vaults. Pleasejustify why the water, debris, and sediments were not removed prior to performing the FSS measurements and how these physical constraintsfactoredinto the FSS sampling locationsforthis survey unit. In FR-2600-SU1, Section B, paragraph4, it is noted that the soil samples were also collectedfrom locations where soil and sediment existed in the bottom ofthe vaults. Pleaseprovide soil/sediment samples for all man hole and handholes, the locations and results.

Maine Yankee Response:

CR 05-012 documented the fact that all soil and debris was removed from MH-I. To the extent practical attempts were made to remove all water from the manholes with varying degrees of Page 12

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A success. Other than MH-I, attempts were not made to remove debris and sediment from the duct bank manholes. As shown in the table below, sediment samples were obtained where sufficient sediment was present in manholes.

As discussed in the release record for FR2600 Survey Unit 1, the locations for the 14 direct measurements were randomly generated as required by LTP Section 5.4.4.b. After HH4 was removed in its entirety, one direct measurement had to be relocated. The new location was also randomly generated. Based on the randomly generated X,Y plot, two of the direct measurements (COOS and C010) were located on manhole floors (MH-5 and MH-4a). However, the measurements could not be performed as designed due to the presence of sediment (3") in MH-5 and water (2") in MH-4a.

Consistent with LTP Section 5.4.4.b and in accordance with Maine Yankee Procedure 6.7.1, the direct measurement locations for C005 and COIO were relocated within 1 meter of the design locations. Although these measurements were not taken on the manhole floors, they were located very close to the bottom of the manhole (0.5 m from the floor of the 8 ft deep manholes) where contamination would still likely be found if present. In addition, the direct beta measurements were augmented with ISOCS measurements in both manholes and a sediment sample in MH-5.

The depth of water and sediment were accounted for as shielding in the ISOCS analysis. The additional ISOCS measurements did not identify plant derived activity above the investigation level while the soil sample only identified very low levels of cesium. Based on the results of all measurements, it is judged that the survey design was adequate and the survey unit was appropriately classified a Class 3.

Eight volumetric samples were collected and analyzed with the results shown below.

Location Sample # Co-60 Cs-137 (pCi/g) (pCi/g)

MH2B FR2600-01-3S016 <4.61E-2 4.69E-1 11115 FR2600-01-3S017 <5.83E-2 8.10E-2 MH4B FR2600-01-3S022 <4.47E-2 <4.93E-2 HH7 FR2600-01-3S023 <3.88E-2 <3.77E-2 MHI* FR2600-01-3S024 2.64E-1 3.12E-1 M115 FR2600-01-3S026 <5.62E-2 1.17E-1 HH8 FR2600-01-3S28 <4.96E-2 6.33E-2 HH10 FR2600-01-3S031 <4.10E-2 3.88E-2

  • Pre FSS data, debris in MH-1 was then removed and FSS measurement was taken using ISOCS Page 13

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A The survey unit ambient background value (320 cpm) was determined using Maine Yankee's standard methodology except that, due to limited accessibility to the manholes, the value was calculated retrospectively. Direct measurements were performed in nine of the manholes and hand holes. Prior to obtaining the gross beta measurements at the statistical point locations, a shielded, one-minute scalar background measurement was obtained at a representative location within the manhole/hand hole. A total of ten background measurements were obtained since two sets of measurements were made in MH4b over a two month interval. The mean of the background values was calculated and compared to the individual values to ensure that the individual values fell within procedural requirements. Since the individual values were in tolerance, the mean of the ten background measurements was used as the survey ambient background value. In addition, since the scans were performed with the ISOCS, a design background was not required to establish an alarm setpoint. The background values obtained during the survey are shown below.

Location Ambient Value Location Ambient Value (MH/HH) (cpm) (MHIHH) (cpm)

Cool 331 C006,C007,C012 341 (MH-1) (MH-4b)

C002,C008 321 C009 296 (HH-10) (HH-1 1)

C003, COI1 313 Colo 331 (MH-2a) (MH4a)

C004 338 C013 331 (HH-8) (HH-12)

C005 338 C014 284 (MH-5) (MH-4b)

Page 15

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A References

1. Maine Yankee Letter to USNRC, MN-02-048, dated October 15, 2002, Revision 3, Maine Yankee's License Termination Plan
2. USNRC Letter to Maine Yankee dated February 28, 2003, "Issuance of Amendment No.

168 to Facility Operating License No. DPR Maine Yankee Atomic Power Station -

Approval of the MY License Termination Plan"

3. Maine Yankee Letter to USNRC, MN-04-020, dated March 15, 2004, License Amendment Request: Release of Non-ISFSI Site Land, Proposed Change No. 218
4. USNRC Memorandum from John T. Buckley to Claudia M. Craig dated March 23, 2004, Meeting Report for the March 17, 2004, Meeting with Maine Yankee Atomic Power Company (Maine Yankee)
5. USNRC Memorandum from John Buckley to Biweekly Notice Coordinator dated May 5, 2004, Request for Publication in Biweekly FR Notice - Notice of Consideration of Issuance of Amendment to Facility Operating License DPR-26, Proposed No Significant Hazards Consideration Determination, and Opportunity for Hearing (TAC No. L52090)
6. Maine Yankee Letter to USNRC, MN-04-03 1, dated May 6, 2004, Release of Non-ISFSI Site Land - FSS Final Report No. IA, Proposed Change No. 218, Supplement 1
7. Federal Register Biweekly Notice: Applications and Amendments to Facility Operating Licenses Involving No Significant Hazards Consideration - Maine Yankee, 69FR29768, dated May 11, 2004
8. Maine Yankee Letter to USNRC, MN-04-042, dated July 6,2004, Maine Yankee License Amendment Request - Release of Non-ISFSI Site Lands
9. USNRC Letter to State of Maine dated July 30, 2004, Response to State of Maine Comments on Maine Yankee License Amendment Request - Release of Non-ISFSI Site Lands
10. Maine Yankee Letter to USNRC, MN-04-044, dated August 12, 2004, Release of Non-ISFSI Site Land - Resubmittal of FSS Final Report No. 1, Proposed Change No. 218, Supplement 2
11. USNRC Letter to Maine Yankee dated August 18, 2004, Integrated Inspection No.

05000309/2004001

12. USNRC Letter to Maine Yankee dated August 18, 2004, Changes to the Maine Yankee Atomic Power Station License Termination Plan Using the 50.59 Process
13. Maine Yankee Letter to USNRC, MN-04-047, dated September 2, 2004, License Amendment Request - Release of Non-ISFSI Site Land, Proposed Change No. 218, Supplement 3
14. Maine Yankee Letter to USNRC, MN-04-048, dated September 7, 2004, Reply to NRC Letters Re: Changes to Maine Yankee LTP Using 50.59 Process
15. USNRC Letter to Maine Yankee dated October 14, 2004, Meeting Report for the September 9, 2004, Meeting with Maine Yankee Atomic Power Company (Maine Yankee)

Page 16

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A

16. Maine Yankee Letter to USNRC, MN-04-049, dated September 15, 2004, Release of Non-ISFSI Site Land - FSS Final Report No. 2, Proposed Change No. 218, Supplement 4
17. USNRC Letter to Maine Yankee dated September 24, 2004, Request for Additional Information Regarding Final Status Survey (FSS) Final Report No. 1A.
18. Maine Yankee Letter to USNRC, MN-04-052, dated October 12, 2004, Release of Non-ISFSI Site Land - FSS Final Report No. 3, Proposed Change No. 218, Supplement 5
19. Maine Yankee Letter to USNRC, MN-04-053, dated October 14, 2004, Release of Non-ISFSI Site Land - Addendum to FSS Final Report No. 1, Proposed Change No. 218, Supplement 6
20. USNRC Letter to Maine Yankee dated November 4, 2004, Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Supplement Nos. I and 3
21. Maine Yankee Letter to USNRC, MN-04-056, dated November 17, 2004, Release of Non-ISFSI Site Land - FSS Final Report No. 4, Proposed Change No. 218, Supplement 7
22. USNRC Letter to Maine Yankee dated November 17, 2004, Maine Yankee - NRC Inspection Report NO. 05000309/2004001 and NRC Office of Investigations Report No.

1-2004-001

23. USNRC Letter to Maine Yankee dated November 22, 2004, Correction to NRC Letter to Maine Yankee, dated November 17, 2004.
24. USNRC Letter to Maine Yankee dated November 30, 2004, Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Supplement No. 2
25. USNRC Letter to Maine Yankee dated November 30, 2004, Receipt of Final Status Survey (FSS) Supplement No. 4.
26. Maine Yankee Letter to USNRC, MN-04-058, dated December 7, 2004, Response to NRC RAI's on FSS Report Nos. I and 3, Proposed Change No. 218, Supplement 8
27. Maine Yankee Letter to USNRC, MN-04-059, dated December 7,2004, Release of Non-ISFSI Site Land - FSS Final Report No. 5, Proposed Change No. 218, Supplement 9
28. Maine Yankee Letter to USNRC, MN-04-060, dated December 22, 2004, Release of Non-ISFSI Site Land - FSS Final Report No. 6, Proposed Change No 218, Supplement 10
29. Maine Yankee Letter to USNRC, MN-04-061, dated December 23, 2004, Response to NRC RAI's on FSS Report No. 2, Proposed Change No. 218, Supplement 11
30. USNRC Letter to Maine Yankee dated December 29,2004, Receipt of Maine Yankee Final Status Survey Report Supplements 5 and 6
31. USNRC Letter to Maine Yankee dated January 5, 2005, Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Supplement No. 4
32. USNRC Letter to Maine Yankee dated January 7, 2005, Receipt of Maine Yankee's Response to Request for Information on Final Status Survey Report Supplements 1 and 3
33. USNRC Letter to Maine Yankee dated January 19, 2005, Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Supplement No. 2
34. Maine Yankee Letter to USNRC, MN-05-001, dated January 20, 2005, Release of Non-ISFSI Site Land - FSS Final Report No. 7, Proposed Change No. 218, Supplement 12
35. Maine Yankee Letter to USNRC, MN-05-002, dated January 26, 2005, Technical Basis Document forNRC Review: Exploranium GR-130 Minimum Detectable Concentration (MDC) of Cs-137 and Co-60 in Surface Soil - 30 Day Notice per LTP Requirement Page 17

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A

36. Maine Yankee Letter to the NRC, MN-05-003, dated January 26, 2005, Area Classification Change: Storm Drains (D3500) - Section 7
37. Maine Yankee Letter to USNRC, MN-05-004, dated January 27, 2005, Response to NRC RAI on FSS Report No. 4, Proposed Change No. 218, Supplement 13
38. USNRC Letter to Maine Yankee dated January 27, 2005, Receipt of Maine Yankee Final Report Supplement 7
39. USNRC Letter to Maine Yankee dated February 9, 2005, Response to Area Classification Change: Storm Drains (D3500)
40. Maine Yankee Letter to USNRC, MN-05-006, dated February 16, 2005, Response to NRC RAI's on FSS Final Report Nos. 1 and 2, Proposed Change No. 218, Supplement 14
41. Maine Yankee Letter to USNRC, MN-05-007, dated February 17, 2005, Release of Non-ISFSI Site Land - FSS Final Report No. 8, Proposed Change No. 218, Supplement 15
42. Maine Yankee Letter to USNRC, MN-05-008, dated February 23, 2005, Release of Non-ISFSI Land - FSS Final Report No. 8 - Attachment I, Figure 1 and 2 and Attachment II Header Page, Proposed Change No. 218, Supplement 16
43. Maine Yankee Letter to USNRC, MN-05-009, dated February 23, 2005, Response to NRC Comments on Maine Yankee Area Classification Change: Storm Drains (03500) -

Section 7

44. USNRC Letter to Maine Yankee dated February 23, 2005, Receipt of Maine Yankee Responses to Requests for Additional Information Regarding Supplements 1 and 2 and Final Status Survey Report Supplement 8
45. USNRC Letter to Maine Yankee dated February 24, 2005, Acceptance of Maine Yankee Technical Basis Document for the Limited Use of the Exploranium GR-130 Instrument
46. USNRC Letter to Maine Yankee dated March 2, 2005 ', Approval of Final Status Survey Supplement No. 4
47. USNRC Letter to Maine Yankee dated March 13, 2005, Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Supplement No. S
48. USNRC Letter to Maine Yankee dated March 21, 2005, Storm Drain Area Survey Unit Classification Change
49. USNRC Letter to Maine Yankee dated March 28, 2005, Review of Maine Yankee Response to NRC RAP's on FSS Report Nos. 1 and 2
50. Maine Yankee Letter to USNRC, MN-05-015, dated April 7, 2005, Response to NRC RAI on FSS Final Report No. 5, Proposed Change No. 218, Supplement 17
51. Maine Yankee Letter to USNRC, MN-05-016, dated April 7,2005, Release of Non-ISFSI Site Land - FSS Final Report No. 9, Proposed Change No. 218, Supplement 18
52. USNRC Letter to Maine Yankee dated April 7, 2005, Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Supplement No. 6
53. Maine Yankee Letter to USNRC, MN-05-017, dated April 13, 2005, Response to NRC RAI of FSS Final Report Nos. 1 and 2, Proposed Change No. 218, Supplement 19
54. USNRC Letter to Maine Yankee dated April 15, 2005, Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Supplement No. 7 This letter was erroneously dated "March 2,2003" and should have been "March 2,2005" Page 18

ATTACHMENT Maine Yankee Response to NRC Request for Additional Information (RAI) Regarding Final Status Survey (FSS) Final Report No. 9A

55. USNRC Letter to Maine Yankee dated May 3, 2005, Meeting Report for the April 19, 2005, Meeting with Maine Yankee Atomic Power Company (Maine Yankee)
56. Maine Yankee Letter to USNRC, MN-05-019, dated May 5, 2005, Response to NRC RAI on FSS Final Report No. 6, Proposed Change No. 218, Supplement 20
57. Maine Yankee Letter to USNRC, MN-05-020, dated May 5, 2005, Release of Non-ISFSI Site Land - FSS Final Report No. 9A, Proposed Change No. 218, Supplement 21
58. Maine Yankee Letter to USNRC, MN-05-23, dated May 10, 2005, Release of Non-ISFSI Site Land - FSS Final Report Nos. I and 2 - Resolution, Proposed Change No. 218, Supplement 22
59. USNRC Letter to Maine Yankee dated May 12, 2005, Approval of Final Status Survey Supplement Nos 8. and 9
60. Maine Yankee Letter to USNRC, MN-05-024, dated May 16, 2005, Response to NRC RAI on FSS Final Report No. 7, Proposed Change No. 218, Supplement 23
61. Maine Yankee Letter to USNRC, MN-05-025, dated May 16,2005, License Amendment Request: Release of Non-ISFSI Site Land, Proposed Change No. 218, Supplement 24
62. Maine Yankee Letter to USNRC, MN-05-026, dated May 17,2005, Conditional Acceptance of FSS Final Reports, Proposed Change No. 218, Supplement 25
63. Maine Yankee Letter to USNRC, MN-05-028, dated May 25, 2005, Release of Non-ISFSI Site Land - FSS Final Report No. 10, Proposed Change No. 218, Supplement 26
64. Maine Yankee Letter to USNRC, MN-05-03 1, dated June 20, 2005, Release of Non-ISFSI Site Land - FSS Final Report No. 1OA, Proposed Change No. 218, Supplement 27
65. USNRC Letter to Maine Yankee dated June 23, 2005, Request for Additional Information Regarding Maine Yankee Final Status Survey Report Supplement 9A
66. Maine Yankee Letter to USNRC, MN-03-051, dated September 3, 2003, Technical Basis Document for NRC Review: Forebay FSS Survey Measurement Methods (In situ gamma Spectroscopy) - 30 Day Notice per LTP Requirement
67. USNRC Letter to Maine Yankee dated September 30, 2003, Comments on Forebay FSS Survey Measurement Methods (In Situ Gamma Spectroscopy)
68. Maine Yankee Letter to USNRC, MN-03-067, dated October 21, 2003, Maine Yankee Response to NRC and State of Maine Comments on the Technical Basis Document for NRC Review: Forebay FSS Survey Measurement Methods (In situ gamma Spectroscopy)

Page 19

Appendix A ISOCS Investigation Level for Concrete (FA-0400-01)

The investigation level for ISOCS measurements on concrete were evaluated using an approach similar to that used for determining for soil. The investigation level for ISOCS measurements was set at the DCGL of 18,000 dpm/l 00cm 2 (1,800,000 dpm/m2 ). This investigation level ensured that a small area of elevated activity at the DCGLEmC located at the periphery of the detector's field of view would be investigated.

For an area of elevated activity the size of 1m2, the DCGLEJmC is 18,000 dpm/I00cm2 x (50/lm2) = 900,000 dpm/100cm 2 For an area of elevated activity the size of 100cm2, the DCGL"4c is 18,000 dpm/100cm2 x (50/0.01m 2 ) = 90,000,000 dpm/100cm2 In order to detect these levels of activity in their respective sized areas at the periphery of the field of view, the investigation level seen by the detector would have to be set at or lower than the following.

1 m2 area 100 cm2 area Cs-137 Co-60 Cs-137 Co-60 dpm/l00cm2 dpm/100cm2 dpm/100cm 2 dpm/I00cm 2 1 72,400 55,100 40,100 28,600 These values were determined using actual measurements for the detector set at a 12.6 m2 field of view and attributing the activity to the respective sized areas at the periphery of the field of view to derive the mean ratio between the activity measured in the small area at the periphery to the activity measured in the entire field of view. This method of evaluating the ISOCS investigation levels was similar to that used for evaluating the ISOCS investigation levels for soil.

Appendix B FA-0400 SU 1 Fuel Building Remediation Surveys dated March 20, 2005 and April 7, 2005 Notes:

I. Remediation Survey dated March 20, 2005 and April 7, 2005 identifies four areas of ledge with a SPA measurement greater than 30 kcpm. These areas were measured with ISOCS resulting in no plant derived activity identified at MDA's provided below:

SPA-3 ISOCS # Co-60 MDA Cs-I 37 MDA (kcpm) (dpm/100cm 2 ) (dpm/lOOcm 2 )

34 2-4B 1150 1995 40 2-4A 830 1421 54 W-10 1204 1831 35 W-15b 1194 1590

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Appendix C FA-01lI SU 16 Yard West Excavation Areas Remediation Surveys dated March 19-31, 2005 and April 6,2005 Notes:

I1. Remediation Survey dated March 19 & 31, 2005 identifies an area of soil with a SPA measurement of 35 kcpm. This area of soil was remediated prior to FSS and was measured with ISOCS resulting in no plant derived activity identified at MDA's provided below:

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