ML063330062
| ML063330062 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 11/21/2006 |
| From: | Redeker S Sacramento Municipal Utility District (SMUD) |
| To: | Document Control Desk, NRC/FSME |
| References | |
| MPC&D 06-115 | |
| Download: ML063330062 (66) | |
Text
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.SACRAMENTO The Power To MUNICIPAL
- DoMore:mUTILITY DISTRICT P.O. Box 15830, Sacramento, CA 95852-1830; 1-888-742-SMUD (7683)
MPC&D 06-115 November 21, 2006 U.S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555 Docket No. 50-312 Rancho Seco Nuclear Generating Station License No. DPR-54 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION Attention: John Hickman In your letter dated October 24, 2006, you requested additional information required to complete the NRC's review and approval of the Rancho Seco License Termination Plan (LTP). Attached is our response to your request. Members of your staff with questions requiring additional information or clarification may contact Bob Jones at (916) 732-4843.
Sincerely, Steve Redeker Manager, Plant Closure & Decommissioning Attachment Cc w/ attachment: B.S. Mallett, NRC, Region V Nt"rM S RANCHO SECO NUCLEAR PLANT
- 14440 Twin Cities Road, Herald,CA 95638-9799; (209) 333-2935
Response to RAIs Dated October 24, 2006 General Issues
- 1. Chapter 2, Section 2.1.4.3, page 2-4 The first sentence states that a formal site reconnaissance was not performed.
However, in the next sentence it states that appropriate site reconnaissance has been performed. Explain the difference between a formal site reconnaissance and the appropriate site reconnaissance.
Response
A "formal site reconnaissance" would be performing the full scope of the "Site Reconnaissance or Site Visit" as described by MARSSIM section 3.5. As explained below, such a full scope reconnaissance was not warranted and a reduced scope or "appropriate" reconnaissance was performed. The term "appropriate site reconnaissance" will be deleted as described below.
Chapter 2, Section 2.1.4 of the License Termination Plan (LTP) is a summary description of the methodology used to perform the Historical Site Assessment (HSA).
Section 2.1.4.3 refers to the "Site Reconnaissance or Site Visit" described in MARSSIM (NUREG-1575) Section 3.5, which also states: "This section is most applicable to sites with less available information and may not be necessary at other sites having greater amounts of data, such as Nuclear Regulatory Commission (NRC) licensed facilities."
The last sentence of LTP Section 2.1.4.3 will be clarified to read:
"Investigations were performed to verify locations and current conditions of questionable items or issues (radioactive liquid spills or spread of contamination) discovered during review of historical records or the conduct of personal interviews."
- 2. Chapter 2, Section 2.1.4.4, page 2-4 The term "observation" is used but not defined. Clarify want is meant by observation. What was observed? What constitutes an observation?
Response
An "observation" is a comment made by an individual who was interviewed that contained information about the interviewees' knowledge of systems, facilities or areas where there may have been a radiological impact that was not already identified on a list provided to the interviewee.
November 20, 2006 Page 1 of 31
Response to RAIs Dated October 24, 2006 Chapter 2, Section 2.1.4.4 summarizes the use of personnel interviews, including the use of questionnaires, of current, former and retired plant personnel to confirm documented incidents and identify undocumented incidents during performance of the HSA.
LTP Section 2.1.4.4 will be clarified through addition of the parenthetical expression
"(knowledge of any systems, facilities, or areas of potential radiological impact not already identified on the Rancho Seco Historic Site Assessment Questionnaire)"
after the first use of the term "observation".
- 3. Chapter 2, Section 2.1.5.7.2, Discharge Canal Soil, page 2-13 Were other radionuclides, such as hard-to-detect radionuclides, analyzed for?
Were attempts made to detect hard-to-detect radionuclides in this area? And if so, what were the results? Is the discharge Canal Soil area still contaminated as stated on page 2-11?
Response
Even though characterization data is available for all areas (samples and/or surveys),
not all samples taken have been analyzed for hard-to-detect radionuclides (HTDs). In this case, Discharge Canal Soil samples were not analyzed for HTDs. This soil has not been remediated and is still has detectable activity.
The Discharge Canal Soil is within the Effluent Corridor, which is also referred to as the Effluent Water Course. The Effluent Corridor or Effluent Water Course area soils (Discharge Canal Sediment, Discharge Canal Soil, Depression Area Soil) are all impacted from the same source; i.e., radioactivity in liquid effluents. Samples from all of these areas were taken and analyzed onsite during the characterization process.
However, as a general rule, only the samples exhibiting the highest activities were analyzed for HTDs because: 1) those are the samples with the most likelihood of a positive result for the HTDs, and 2) those are the samples that would provide the most reasonable basis for surrogate ratios of HTDs to nuclides detectable with onsite laboratory equipment. In this case, samples of the Depression Area Soil were taken and analyzed for HTDs since this is the most highly impacted soil representative of this region.
The results of the offsite analysis of HTDs in site soils is contained in DTBD-05-014, "Rancho Seco Nuclear Generating Station Surface Soil Nuclide Fraction and DCGL,"
[Reference 2-27] as referenced in Section 2.5.5 of this LTP. Table 2-26, taken from DTBD-05-014, shows the nuclide fraction basis for site soils for HTDs.
November 20, 2006 Page 2 of 31
Response to RAIs Dated October 24, 2006 The paragraph under Table 2-25 on Page 2-55 will be amended as follows (amended text italicized here but will not be in the LTP):
"...The soil nuclide fraction, including the hard-to-detect radionuclides, is provided in Table 2-26. This nuclide fraction applies to all site soils."
- 4. Chapter 2, Section 2.1.5.7.2, Depression Area Soil, page 2-13 The text indicates that you are sending the results to an offsite vendor laboratory for the analysis for hard-to-detect radionuclides. However, on the next page, page 2-14, Table 2-4, two radionuclides, Co-60 and Cs-137, which are gamma emitters and not hard-to-detect .radionuclides are reported. Were hard-to-detect radionuclides analyzed for? And if so, what were the results?
Response
A composite sample taken from 4 samples in the Depression Area was sent for offsite analysis. The text states "a composite sample... representing the highest concentrations was sent to a vendor laboratory for hard-to-detect-nuclide analysis."
In order to work with a single data set when observing nuclide fractions within a sample, SMUD had required the vendor lab to analyze for the entire suite of nuclides of concern for each sample, not only the HTDs. As stated in the last sentence on Page 2-13, Table 2-4 reports all radionuclides that were detected in the sample by the offsite vendor laboratory at levels above the minimum detectable activity (MDA), both gamma emitters and HTDs. Co-60 is also reported even though below the MDA because of its significance overall for the site.
Revision of the LTP is not warranted in response to this request for additional information (RAI).
- 5. Chapter 2, Section 2.1.5.7.2, page 2-14, Remainder of the Non-Industrial Area What were the "selected areas" outside of the Industrial Area?
Response
The "selected areas" outside of the Industrial Area are shown in Figure 1 below.
November 20, 2006 Page 3 of 31'
Response to RAIs Dated October 24, 2006 Figure 1 Within the "selected areas" survey blocks were identified for conduct of the radiological surveys. Figure 2 below shows the survey blocks indicated with the blue rectangles.
Each survey block is nominally 48 meters by 100 meters. In general, an in situ measurement was taken at the southwest corner of each survey block, and one soil sample was taken for every two survey blocks, the sample location being within a meter of the in situ measurement for that block.
November 20, 2006 Page 4 of 31
Response to RAIs Dated October 24, 2006 Figure 2 Revision of the LTP is not warranted in response to this RAI.
- 6. Chapter 2, Section 2.1.10, page 2-24 The License Termination Plan (LTP) states, "There were periods of liquid effluent releases during operation of the plant where it was determined that calculated November 20, 2006 Page 5 of 31
Response to RAIs Dated October 24,2006 dose to a maximally exposed individual via the liquid effluent pathway exceeded the design objective level of 10 CFR 50, Appendix I. However, it was also determined that these liquid effluent releases did not exceed the concentration limits of 10 CFR 20 or the fuel cycle limit of 40 CFR 190. The dose from which has already been accounted for in accordance with the regulation governing radioactive effluent from power plants and no remediation is required."
The assumptions used to determine the dose from the liquid effluent pathway differ from the assumptions used to determine the dose from residual radioactivity remaining in soils or structures. Provide a characterization and evaluation of the potentially affected area(s), and demonstrate compliance with 10 CFR 20 Subpart E.
Response
The paragraph quoted in RAI No. 6 was included to assure complete disclosure regarding offsite liquid releases and is not a basis for License Termination. Refer to the response to RAI No. 7 regarding demonstration of compliance with 10 CFR 20, Subpart E.
The onsite impacts from these historical releases were characterized and discussed in Section 2.5.5 of the LTP. Demonstration of compliance with 10 CFR 20, Subpart E of onsite impacted areas, identified by the HSA and characterization surveys, will be performed by Final Status Survey (FSS) design and performance and by data quality analysis (DQA) of FSS results as described in Chapter 5 of the LTP.
Revision of the LTP is not warranted in response to this RAI.
- 7. Chapter 2, Section 2.1.5.7.2, pages. 2-11 and 2-12 NUREG/CR 4286, which is referenced on page 2-12 in the LTP, states that background levels were reached 19 km from the plant. This was in Laguna Creek. The report also stated that elevated levels of contamination were detected in fish at least 8 km from the plant. Please demonstrate that these areas are in compliance with 10 CFR 20, Subpart E.
Response
The areas referenced are outside the licensed boundary of the plant and as outlined below they are not subject to compliance with 10 CFR 20, Subpart E.
10 CFR 20, Subpart E states that it applies "...to the decommissioning of facilities licensed under Parts 30, 40, 50, 60, 61, 63, 70, and 72 of this chapter, and release of part of a facility or site for unrestricted use in accordance with § 50.83 of this November 20, 2006 Page 6 of 31
Response to RAIs Dated October 24, 2006 chapter..." 1 , Subpart E clearly applies to the 2,480 acre Rancho Seco site described in the licensing basis documents. Since the areas referenced in this RAI are in the environs outside of the licensed Rancho Seco site and were impacted from 10 CFR Part 20.2001(a)(3) authorized radioactive liquid releases, demonstration of compliance with 10 CFR 20, Subpart E in these environs is not required.
Reporting and recordkeeping requirements for decommissioning planning are specified in 10 CFR 50.75. Specifically, 10 CFR 50.75(g)(4)(iii) requires records to be kept of:
"The release and final dispositionof any propertyrecorded in paragraph(g)(4)(i) of this section, the historicalsite assessment performed for the release, radiationsurveys performed to support release of the property, submittals to the NRC made in accordance with § 50.83, and the methods employed to ensure that the property met the radiologicalcriteriaof 10 CFR Part 20, Subpart E, at the time the property was released." The property is specified in paragraph (g)(4)(i) as: "The licensed site area, as originallylicensed, which must include a site map and any acquisition or use of property outside the originally licensed site area for the purpose of receiving, possessing, or using licensed materials."
A similar issue was raised during the LTP Public Meeting held to discuss the Big Rock Point Restoration Project License Termination Plan. A transcript of this meeting is available electronically through the NRC's Agencywide Documents Access and Management System (ADAMS) using accession number ML032340143. On page 36 of the transcript a member of the public asked a question as to what constituted the boundaries of the site requiring cleanup of contamination resulting from liquid radioactive waste discharges into Lake Michigan. The NRC representative's response to the question was that the water line is the end of the Big Rock Point property and that Big Rock Point is not responsible for any contaminates in the Lake Michigan sediment because the contaminates were the result of legal discharges into Lake Michigan and that the sediments are not on Big Rock Point property.
The authorized radioactive liquid releases that resulted in the NRC contracting with the Oak Ridge National Laboratory (ORNL) to conduct the study reported in NUREG/CR-4286 were historical events that occurred prior to the late summer of 1984.
The consequences of the authorized radioactive liquid releases were the subject of studies conducted by Rancho Seco personnel, ORNL and Lawrence Livermore National Laboratory (LLNL) contracted by SMUD. This was one of eight studies of the liquid effluent pathway conducted since 1984 as part of the Environmental Exposure Controls Action Plan, which was described in the NRC Inspection Report 50-312/90-02, dated February 1, 1990. By letter AGM/NUC 92-241 from James R. Shetler (SMUD) to J. B. Martin (NRC), SMUD notified the NRC of completion of the Environmental Exposure Controls Action Plan.
The conclusion of the Action Plan was a calculation of doses that an assumed offsite individual would receive from three pathways; 1) drinking the creek water, 2) eating the fish, and 3) standing on the sediment. The results of the calculation showed that even 1 10 CFR § 20.1401 November 20, 2006 Page 7 of 31
Response to RAIs Dated October 24, 2006 the maximum exposed individual would receive less than 2 mrem per year from any of the pathways.
Revision of the LTP is not warranted in response to this RAI.
- 8. Chapter 2, Section 2.4.7, page 2-45 This section states, "Several areas of the site were specifically targeted for detailed sampling and surveys." Describe what areas were specifically targeted for detailed sampling and surveys and provide results.
Response
Areas specifically targeted were the Regenerant Holdup Tank (RHUT) and area, the Tank Farm, the Spent Fuel Cooler Pad, the soils adjacent the Plant Effluent Water Course, the Fuel building West exterior wall, Spent Fuel Pool and Upender Pit walls and floor, soil beneath the Spent Fuel Pool, activated concrete in the Bioshield, suspect Co-60 dominant areas within the Auxiliary and Reactor buildings and the Barrel Farm.
The results are included in Chapter 2 and Tables 5-4A through 5-4E of Chapter 5 of the LTP.
Revision of the LTP is not warranted in response to this RAI.
- 9. Chapter 2, Section 2.4.7.1, page 2-46, Paragraph after last bullet on page This section states, "The nuclide suite includes those nuclides and the suite is found in Chapter 6 of this LTP." This sentence is unclear. Please clarify.
Response
The paragraph will be clarified to read:
"With the exception of Bioshield concrete and rebar, samples submitted to the vendor laboratory were analyzed for the entire suite of 26 radionuclides. The radionuclide suite is presented in Table 6-1 of Chapter 6. The Bioshield Concrete and rebar acquired from the mid-core region (-2'6" Elevation) were analyzed for radionuclides expected to be found in activated media. These radionuclides include: H-3, C-14, Fe-55, Co-60, Ni-63, Cs-134, Eu-152, Eu-154 and Eu-155. Of the radionuclides listed in Chapter 6, Table 6-1 the following were not included in the analysis of activated concrete and rebar: Sr-90, Tc-99 Pm-147, Np-237, Pu-238 through Pu-242, Am-241 and Cm-244. The latter radionuclides are not concrete and rebar activation products but could be found on November 20, 2006 Page 8.of 31
Response to RAIs Dated October 24, 2006 external surfaces of activated concrete and are addressed using the radionuclide mix for structures and surfaces provided in Section 2.5.1."
- 10. Chapter 2, Table 2-15, page 2-47 Please provide more detailed information regarding the concentration(s). More specifically, what radionuclides(s) do these concentrations represent?
Response
Table 2-15 was intended to provide a general range of soil concentrations observed over the site area. The concentrations represent onsite gamma spectroscopy analysis results of which the principle nuclides are Cs-137 and Co-60. Some of the locations in Table 2-15 are the same locations provided in Table 2-25 and will be changed as follows:
Table 2-15 Specific Soil Contamination Investigation Locations Concentration Vendor Lab (pCi/g) Analysis Spent Fuel Cooler Pad 5-1100 Yes Tank Farm 18-120 Yes Spent Fuel Pool Diesel Generator 50-1200 Yes Room Gap Plant Effluent Water Course <1.0-23 Yes RHUT Tank Area 20-100 No Old Bechtel Bldg pad <0.5 No Locations outside the power block <1.0 No The paragraph immediately above Table 2-15 will be modified to read:
"The concentrations provided in Table 2-15 present gross concentrations in pCi/g observed using onsite gamma spectroscopy. The onsite soil gamma-emitting nuclide mixture consists primarily of Cs-1 37, Cs-1 34 and Co-60 of which the averaged Cs-1 37 concentration is greater than 90 percent of the mixture. The results of the detailed soil sampling and analysis were reported in DTBD-05-014 and formed the basis for the soil nuclide fractions. The sample locations in Table 2-15 where vendor laboratory analysis was performed were reported in DTBD-05-014 and are also presented in Section 2.5.5, Table 2-25 of this chapter."
November 20, 2006 Page 9 of 31
Response to RAIs Dated October 24, 2006
- 11. Chapter 2, Section 2.5.1, page 2-48 This paragraph is awkward. For example, it refers to a mean but provides a range. It discusses hard-to-detect analyses, but indicates Co-60 and Cs-137 which are gamma emitters and are easy to detect radionuclides. The paragraph raises the issue about hard-to-detect radionuclides, but provides no information or data about the presence of these radionuclides.
Response
The mean values for each structure will be clarified along with a narrative on the hard to detect nuclides associated with structure surfaces. The information, which will replace the entire first paragraph for Section 2.5.1, (above Table 2-16) is as follows:
The mean direct beta contamination values as measured by gas flow proportional detectors for the Reactor, Auxiliary, Fuel and Turbine Buildings are provided below.
Reactor Building
. -27' Elevation 1.50E+06 dpm/100 cm 2 Grade Level 2.OOE+05 dpm/100 cm 2 0
+40' Elevation 5.1OE+04 dpm/100 cm 2
+60' Elevation 2.OOE+04 dpm/100 cm 2 Auxiliary Building
-47' Elevation 3.20E+05 dpm/100 cm 2
-29' Elevation 5.40E+05 dpm/100 cm 2
-20' Elevation 2.50E+05 dpm/100 cm 2 Grade Level 3.70E+05 dpm/100 cm 2
+20' Elevation 8.50E+04 dpm/100 cm 2 3.30E+03 dpm/100 cm 2
- +40 E--ulevation Fuel Building 2
- Spent Fuel Pool Floor 1.70E+07 dpm/100 cm 2
- +40' Elevation 5.90E+03 dpm/100 cm Turbine Building 2
- -7' Elevation 3.10E+03 dpm/100 cm 2
- Grade Level 2.30E+03 dpm/100 cm 2
- Mezzanine 1.60E+03 dpm/100 cm 2
- +40' Elevation 2.8E0+03 dpm/100 cm The mean, maximum and standard deviation of surface activity for each of the structures are provided in Tables 5-4A through 5-4E in Chapter 5 of this LTP.
Additionally, Seventy-five volumetric samples representing contaminated structure surfaces were examined and used to identify the radionuclide constituents and to determine the gross beta DCGL for structures. Eight of these samples were submitted for radionuclide analysis by a vendor laboratory. The samples were analyzed for the radionuclide suite presented in Chapter 6, Table 6-1. The eight samples represent the November 20, 2006 Page 10 of 31
Response to RAIs Dated October 24, 2006 highest activity samples available from each principal building (Turbine, Fuel, Auxiliary and Reactor Buildings) and subsequently the greatest chance of establishing the ratios of the hard to detect radionuclides including the TRU's that are usually present at very low levels in comparison to the site's principal and easily detected nuclides, Co-60 and Cs-137. DTBD-05-015, "Rancho Seco Nuclear Generating Station Structure Nuclide Fraction and DCGLs," [Reference 2-26] describes the process for examination of the samples submitted for vendor analysis and the determination of the nuclide fraction for site structures. The following hard to detect radionuclides were reported as positive results by the vendor laboratory: H-3, C-14, Fe-55, Ni-59, Ni-63, Sr-90, Tc-99, Pu-238, Pu-239, Pu-240, Pu-241 and Am-241. Of these radionuclides, H-3, C-14, Fe-55, Ni-59, Ni-63 and Tc-99 were removed from the mixture based on their small dose contribution to the building occupant. Hard to detect analyses of concrete samples showed that the nuclide fraction was dominated by Cs-137 and Co-60 (90% or more of the individual sample nuclide fractions) with the remainder being the hard to detect radionuclides.
The concrete nuclide fractions for the site structures other than "special areas" is shown in Table 2-16 below.
- 12. Chapter 2, Figure 2-14 to 2-21 (pages 2-73 thru 2-80)
There is no legend associated with these figures. There was a legend found on page 2-111 but it is not clear whether this legend applies to these figures.
Please provide a legend or legends that represent all the figures in this chapter of the LTP.
Response
The legend found on page 2-111 applies to all of the figures in Chapter 2.
Revision of the LTP is not warranted in response to this RAI.
- 13. Chapter 2, Table 2-17, page 2-49 This table cites structures with contamination levels below the derived concentration guideline levels (DCGL). Please provide a table that shows all structures with levels that are above the DCGL.
Response
Table 5-4D in Chapter 5 of the LTP shows all the structures that, prior to remediation, had contamination above the DCGL as well as structures that had no contamination above the DCGL. Contamination levels for the major site buildings are given by elevation.
Revision of the LTP is not warranted in response to this RAI.
November 20, 2006 Page 11 of 31
Response to RAIs Dated October 24, 2006
- 14. Chapter 2, Table 2-17, page 2-49 The maximum direct beta for exterior surfaces for the Bulk Waste Building was reported as 6.99E+4 dpm/100 cm 2 . On page 2-48, first sentence, next to last paragraph, it states that the gross beta DCGL for surfaces and structures is 4.30 E+04 dpm/100 cm 2 . The value reported in Table 2-17 exceeds the DCGL.
This is not consistent with the title of the table. Please provide an explanation for this discrepancy and correct it, if necessary.
Response
The Bulk Waste Storage Building will be removed from Table 2-17 and the last sentence on page 2-48 will be revised to state:
"Site structures determined to have levels of residual radioactivity below the DCGLs are provided in Table 2-17 below."
- 15. Chapter 2, Section 2.5.1.1, page 2-49 Please provide more detail on what constitutes a special area.
Response
The Term, "special areas" is defined in DTBD-05-015 as areas of the site that have significantly different nuclide ratios, which require separate DCGLs. The definition for special areas will be entered as the introductory sentence to Section 2.5.1 of Chapter 2 of the LTP as:
"Special Areas are defined as areas of the site that have significantly different nuclide ratios, which require separate DCGLs."
- 16. Chapter 2, Section 2.5.1.1, page 2-50 This section states, "Sample locations 10-16, 18, 26, and 28 in Figure 2-14 depict the Special Area sample locations in Table 2-18." Table 2-18 on page 2-50 identifies 7 locations. According to the number of locations that are shown on Figure 2-14, and depending on how 10-16 is defined, the number of sample locations could be as few as 4 locations or as many as 10 locations. There does not appear to be any consistency between what is shown in Table 2-18 and what is shown in Figure 2-14. Please correct this discrepancy.
November 20, 2006 Page 12 of 31
Response to RAIs Dated October 24, 2006
Response
The last sentence of Chapter 2, Section 2.5.1.1 and Table 2-18, will be clarified to read:
"Sample locations 10, 14-16, 18, 26 and 28 depict the Special Area sample locations described in Table 2-18. The identified Special Areas consist of four survey areas; the East Decay Heat Cooler Room, Seal Return Cooler Room, Crud Tank Pump Room and the Miscellaneous Waste Filter Room."
The Location Descriptions in Table 2-18 will be modified to include the sample location number as follows:
Table 2-18 Special Area Locations Sample Location Co-60 Nuclide Cs-137 Nuclide Code Description** Fraction* Fraction*
SB8130690 East Decay Heat 0.806 0.195 SC03A Cooler Room (10)
SB8130640 Seal Return SC02A Cooler Room (14)
SB8130660 Crud Tank Pump Room 0.868 0.132 SC02 (15)
SB8130670 Crud Tank Pump Room 0.866 0.134 SCOl (16)
SB8130670 Crud Tank Pump Room 0.775 0.226 SC02 (18)
SB8130350 Miscellaneous Waste Filter Room (26) 0.788 0.212 SC02 SB8130350 Miscellaneous SC04 Waste Filter Room (28)
- Co-60 and Cs-1 37 nuclide fractions have been normalized, see DTBD-05-015
- The numbers in parenthesis are the sample locations found in Figure 2-14.
- 17. Chapter 2, Table 2-19 Does the concentration in Table 2-19 for the Reactor Bioshield Core and Reactor Bioshield Core Rebar represent the average value of the six core samples or the highest value of the six core samples? It is not clear as to what the concentration for each sample represents.
Response
The radionuclide results in Table 2-19 present the maximum radionuclide concentrations for the Bioshield. These sample results represent one concrete core November 20, 2006 Page 13 of 31
Response to RAIs Dated October 24, 2006 sample and metal from rebar removed from near the "face" of the same core. The core and rebar were obtained from the reactor vessel mid-core (-2' 6" elevation) which is the region of highest activation.
The third bullet item of Chapter 2, Section 2.5.1.2 identifies the -2' 6" Elevation as a mid-core (centerline of the reactor core) level of the reactor vessel. Paragraph 5 of this Section identifies the -2' 6" Elevation core and metal rebar sample as submitted to the vendor laboratory but mis-identifies the sample location as the 2' 6" Elevation. There are missing minus signs in Paragraph 4 and in Table 2-19. The minus (-) elevation symbols will be appropriately added to the text of paragraphs 4 and 5 as well as Table 2-19.
- 18. Chapter 2, Section 2.6, page 2-58 "As previously stated, characterization data will be collected as necessary throughout the project. Results of future characterization sample analyses will be evaluated to determine the impact, if any, on the radionuclide identifies, nuclide fractions and the classification of structures, soils, and other site media."
Please provide a reference for "previously stated"
Response
The reference for "previously stated" is Section 1.5.2 of Chapter 1 of the LTP. This section of Chapter 1 discussed the status of characterization activities at the time of LTP submittal and merely pointed out that site characterization is an ongoing part of decommissioning.
Section 2.6 of the LTP will be revised to add this reference.
- 19. Chapter 2, Section 2.7, page 2-59, last sentence "Furthermore, the current characterization data provide no indication that worker or public health will be adversely affected by the decommissioning."
The report does not make any comparison of health studies of workers or the public with the characterization data. Also, what is meant by adverse? What endpoint was being measured? It is suggested that this statement be removed or revised.
November 20, 2006 Page 14 of 31
Response to RAIs Dated October 24, 2006
Response
The statement will be removed from Section 2.7 of the LTP.
- 20. Chapter 3, Section 3.2.2 (last sentence) page 3-4 This section states, "No significant activity was found below the concrete floor."
Please define quantitatively what is meant by "no significant activity." What would be considered significant?
Response
In this case, the use of "no significant activity" meant "less than a small fraction of the DCGL". The analytical results performed by ORISE can be found in Section 2.5.5 of Chapter 2, which describes the collection of soil samples from beneath the Spent Fuel Pool. The results of the soil analysis performed by ORISE are compared to the site soil DCGLs proposed at the time of sampling are included in Table 2-28.
Revision of the LTP is not warranted in response to this RAI.
- 21. Chapter 3, Section 3.2.4.3, page 3-5 This section states, "Exterior dose rates were 0.2 mrem/hr or less except for a hot spot at the pressurizer bottom where the surge line exits the vessel. To ensure 49 CFR 173.441 radiation limits were met, a carbon steel shielding cover was placed over the surge line and welded to the exterior of the vessel reducing the contact dose rate to less than 200 mrem/hr." What was the dose rate from the hot spot? Why did you elect to shield rather than decontaminate or remediate?
Response
The pressurizer was being shipped as radwaste following commodity removal.
Shielding hot spots to comply with package dose rate limits is a common industry practice that resulted in the workers receiving less dose than they would have received with decontamination of the hot spot. The hot spot prior to shielding was 500 mrem/hr.
Revision of the LTP is not warranted in response to this RAI.
- 22. Chapter 3, Section 3.3.5 (last bullet)page 3-10 This section states, "Upon completion of the Final Status Survey (FSS), the area is placed under periodic routine survey by Radiation Protection to ensure no November 20, 2006 Page 15 of 31
Response to RAIs Dated October 24, 2006 re-contamination occurs. If re-contamination is identified, an investigation will be initiated that would result in corrective actions up to and including re-performance of the FSS for that area." What would constitute recontamination?
Response
Recontamination would constitute the identification of residual radioactivity in excess of that identified during the FSS.
Section 3.3.5 will be revised for clarification and to better summarize the more detailed information on access control measures provided in Section 5.2.4 of the LTP by deleting the bulletized list and adding reference to Section 5.2.4. The last sentence of the remaining paragraph will be revised to read:
"Upon commencement of the FSS for survey areas where there is a potential for re-contamination, isolation and control measures will be implemented as described in Section 5.2.4.4 of this LTP."
The last bullet of Section 5.2.4.4 will be revised to state:
"Periodic surveillance/inspection to monitor and verify adequacy of isolation and control measures."
Also, the last paragraph of Section 5.2.4.4 will be revised to state:
"Periodic surveillances/inspections will not be required for open land areas that are not normally occupied and are unlikely to be impacted by decommissioning activities. Ifthe periodic surveillance/inspection indicates that the adequacy of isolation and control measures has been compromised with the potential for recontamination of the area, post-FSS radiation survey locations will be judgmentally selected for survey, based on technical or site-specific knowledge and current conditions present in or near the survey area. The selected locations will be surveyed using the same instruments and techniques used for the FSS and the results will be compared with those obtained during the FSS to determine whether the area had been re-contaminated. These surveys are primarily designed to detect the potential migration of contaminants from decommissioning activities taking place in adjacent areas."
- 23. Chapter 4, Section 4.4.3.1, page 4-6 This section states, "The characterization data for concrete surfaces at the Rancho Seco facility indicates that a major fraction of the contamination occurs in the top 10 millimeters of the concrete." However, on page 2-46, third bullet, it states, "The results of the sampling provided strong evidence that contamination penetrated deeply into some cracks associated with the concrete." It further November 20, 2006 Page 16 of 31
Response to RAIs Dated October 24, 2006 states, "The results of the characterization contributed significantly to the decision to remove the concrete from the Containment structure down to the plate liner." Please provide clarification and expand the discussion in this area and support the statements with additional data.
Response
Section 4.4.3.1, page 4-6 will revise the statement, "The characterization data for concrete surfaces at the Rancho Seco facility indicates that a major fraction of the contamination occurs in the top 10 millimeters of the concrete" to read:
"Industry experience has shown that a major fraction of concrete contamination occurs in the top 10 millimeters of the concrete."
This should reduce confusion with characterization results reported in Section 2.4.7.1 of the LTP.
Additional data is not required for the discussion in this area. Chapter 4, Section 4.4.3 provides the bases for the determination of costs of various methods of decontamination for the purpose of performing cost/benefit analyses to determine if remediation below the NRC 25 mrem/y dose limit is ALARA.
Section 4.4.3.1 specifically provides the bases for the determination of costs to remediate (scabble) concrete surfaces, not the remediation of contamination that has penetrated the surface into cracks. The bounding cost estimates for scabbled depths of 0.125 and 0.25 inches are based on NUREG/CR-5884, Volume 2, Appendix C estimates as discussed in Chapter 4, Appendix 4-A, Sections A.4.a and A.4.b.
The purpose of the information provided in Chapter 4 is to describe the methods used to reduce residual contamination to levels that comply with the NRC's annual dose limit of 25 mrem plus ALARA and to determine if the cost of remediation below the annual dose limit is ALARA. Therefore, information contained in Section 4.4.3.1 is not applicable to evaluation of the results of characterization surveys provided in Chapter 2 or future FSS surveys to determine if remediation is required to comply with the annual dose limit.
- 24. Chapter 4, Section 4.4.4.1, page 4-7 This section states, "For the evaluation, the truck container is assumed to carry 13.5 m 3 of concrete per shipment based on the NUREG 1757, Volume 2 guidance contained in Table 4.1 ." The parameter value referenced in Table 4-1 for Waste Shipment Volume (Vship) is 13.6 m 3 per shipment. Also, the reference used in this table is not consistent with the reference stated on page 4-7.
Although the difference in values is only 0.1 M 3 , this could have a significant impact on the volume if there are a lot of shipments made during the decommissioning. Please correct this discrepancy.
November 20, 2006 Page 17 of 31
Response to RAIs Dated October 24, 2006
Response
Section 4.4.4.1, page 4-7 incorrectly identifies a truck container volume of 13.5 m 3 of concrete per shipment and should reference NUREG-1496, Volume 2 instead of NUREG-1757, Volume 2. The parameter value referenced in Table 4-1 for Waste Shipment Volume (Vship) of 13.6 m3 per shipment and the source reference for this parameter value are correct as stated. Also, the truck container volume referenced in Appendix 4-A is the correct value of 13.6 m 3 and the calculations performed to generate the data contained in Table 4-2 used the correct value.
LTP Section 4.4.4.1 will be revised to show the correct truck container volume of 13.6 m 3 and the correct source reference of NUREG-1496, Volume 2. Also, the references listed in Section 4.8 will be re-ordered to show the earlier use of NUREG-1496, Volume 2 as a reference.
- 25. Chapter 4, Section 4.4.4.6, page 4-9 This section discusses the excavation of 52,972 cubic feet of soil. However, Section 3, "Identification of Remaining Decommissioning Activities" does not discuss or mention soil excavation. Please correct this discrepancy.
Response
There are no remaining soil excavations planned. The 52,972 cubic feet noted related to an ALARA cost/benefit analysis and did not represent an actual planned excavation activity as described below.
Chapter 4, Section 4.4.4.6 provides the bases for the determination of unit cost of soil excavation for the purpose of performing cost/benefit analyses to determine if remediation below the NRC 25 mrem/y dose limit is ALARA. The selection of a volume of 52,972 cubic feet of soil for this determination corresponds to the resulting volume if the top 15 cm of soil is removed from a 10,000 m2 area (1,500 m 3 or 52,972 cubic feet).
The 10,000 m 2 area is the soil surface area that was used in Chapter 6 of the LTP to perform dose modeling for the purpose of calculating derived concentration guideline values (DCGLs) for soil to demonstrate compliance with the NRC 25 mrem/y dose limit.
Therefore, the information contained in Section 4.4.4.6 and the additional assumptions identified in Appendix 4-A, Section A.7 provide a unit cost for soil excavation based on the dose modeling assumptions contained in Chapter 6.
The purpose of the information provided in Chapter 4 is to describe the methods used to reduce residual contamination to levels that comply with the NRC's annual dose limit of 25 mrem plus ALARA and to determine if the cost of remediation below the annual dose limit is ALARA. Therefore, information contained in Section 4.4.4.6 is not applicable to evaluation of the results of characterization surveys or future FSS surveys to determine if remediation is required to comply with the annual dose limit. Section 4.7 concludes that there is no ALARA justification for remediation beyond that required to November 20, 2006 Page 18 of 31
Response to RAIs Dated October 24, 2006 demonstrate compliance with the annual dose 5imit of 25 mrem and to determine if the cost of remediation below the annual dose limitis ALARA.
Therefore, there is no discrepancy between Section 4.4.4.6 and Chapter 3. Soil excavation was not discussed in Chapter- 3 because, at the time of the preparation of Chapter 3, no soil areas had been identified that required additional remediation to demonstrate compliance
/
with the annual dose limit of 25 mrem.
Revision of the LTP is not warranted in response to this RAI.
- 26. Chapter 5, Section 5.3.6.3.2, page 5-29 Why is the default pipe length 3 meters? Please provide a technical basis for this statement.
Response
Use of 3 meters as the default pipe length for embedded pipe was based on engineering judgment. A review of the cubicle areas in the Auxiliary Building showed typical dimensions of 10 to 20 feet. Assuming the pipe traversed an entire cubicle floor or ran from a floor drain located in the center of the cubicle to the wall resulted in a model pipe length of 10 feet. This length was also consistent with a vertical pipe running from the floor up a cubicle wall (a distance of approximately 10 feet).
The DCGL of 100,000 dpm/100 cm 2 was established based on levels.used as a DCGL by other decommissioning facilities. DTBD-05-009, "Embedded Piping Scenario and DCGL Determination Basis," [Reference 2-28] demonstrates that the annual dose rate to the building occupant would not exceed 0.5 mrem/y from embedded pipe contaminated at the DCGL level. Specifically, for the two highest dose rate scenarios, the annual dose contribution is 0.19 mrem/y and 0.12 mrem/y for Auxiliary Building and Reactor Building pipe respectively. The technical basis document prepared for the Trojan decommissioning showed that the dose rate from pipe greater than 16 feet in length did not change at all. Microshield analyses conducted for the Rancho Seco pipe model showed that, for pipe lengths from 10 feet to 18 feet, the dose rate varied by less than 4%. Increasing the annual dose rates by 4% would have resulted in an annual dose rate of 0.198 mrem/y and 0.125 mrem/y for the Auxiliary and Reactor Building piping respectively. Both of these dose rates were well below the 0.5 mrem/y limit imposed on embedded piping and therefore the 10 foot (3 meter) default value was considered conservative and acceptable.
Revision of the LTP is not warranted in response to this RAI.
November 20, 2006 Page 19 of 31
Response to RAIs Dated October 24, 2006
- 27. Chapter 5, Section 5.4.3.4.3, page 5-43 This section states, "For scan surveys, gross beta measurements appear to be a practical method, under certain conditions, in situ gamma spectroscopy may be a reasonable method for replacing beta scan surveys." Under what conditions would in situ spectroscopy be acceptable? Please describe these conditions.
Response
In situ gamma spectroscopy would be applicable for performing scan surveys provided the area being surveyed has a well known nuclide profile with HTDs being a small fraction of the total activity, clearly established surrogate DCGLs based on the gamma emitters, residual activity present in a known geometry (i.e., material composition, contamination depth, and detector field of view), and investigation criteria established such that the DCGLEMC would not be exceeded. In addition, count times must be long enough to detect the investigation criteria with a 95% confidence level. Examples of such situations would be the Reactor Building liner, remediated concrete structure surfaces, surface soil survey areas, and areas containing activated concrete.
Revision of the LTP is not warranted in response to this RAI.
- 28. Chapter 5, Section 5.8.2.4.1, page 5-57 This section mentions quality control for exposure rate measurements. However, Table 5-11 (pages 5-36 and 5-37) and Table 5-12 (page 5-38) do not show any exposure rate instruments. Please provide an explanation for this discrepancy.
Response
The term "exposure rate measurements" referred to in Section 5.8.2.4.1 was intended to describe any gamma direct measurements performed.
The text in Section 5.8.2.4.1 will be revised to reflect this. The appropriate gamma instrumentation is cited in Table 5-12.
November 20, 2006 Page 20 of 31
Response to RAIs Dated October 24, 2006 DCGL Issues Structural Surface DCGLs 29.2 Page 6-24 of LTP of Section 6.6.3.2 "Derivation of Single Nuclide DCGL Values" An incorrect DTBD document is referenced when describing the development of the results of structural DCGLs and DCF values listed in Table 6-9.
The reference should be changed to DTBD-04-004 "DCGLs for RSNGS Structural Surfaces," [Reference 6-20].
Response
The LTP will be revised to list DTBD-04-004, "DCGLs for RSNGS Structural Surfaces,"
which is the correct title of Reference 6-20.
Bulk Material DCGLs
- 30. Page 6-27 of the LTP, Table 6-10 The DCGL value for Pu-239 is listed as 1.23E+02 pCi/g, but in the DTBD-05-005 "DCGLs for RSNGS Activated and Volumetrically Contamination Bulk Materials,"
Table 6-1, the DCGL value for Pu-239 is listed as 2.96E+02 pCi/g. The DCGL detailed analysis provided for NRC review supports the DCGL value of 2.96E+02 pCi/g listed in the DTBD-05-005.
Provide justification and/or clarification for the different DCGL values for Pu-239 and revise the DCGL value, as appropriate.
Response
The Pu-239 DCGL value of 2.96E+02 pCi/g listed in the DTBD-05-005 is the correct value. Table 6-10 in the LTP will be revised to list 2.96E+02 pCi/g as the DCGL value for Pu-239.
DCGLs from Alternate Resident Farmer Scenario
- 31. Page 6-44 of the LTP, Table 6-19 The total dose listed in the table for 50 years following license termination is 11.6E+01 mrem/y. Adding the listed values for the detected nuclide dose 2 The numbering of the "DCGL Issues" RAIs has been revised to continue the numbering sequence used for the "General Issues" RAIs.
November 20, 2006 Page 21 of 31
Response to RAIs Dated October 24, 2006 (1.07E+01 mrem/y) and the discounted nuclide potential dose (9.50E-01 mrem/y) at 50 years, the total should be 1.165E+01 mrem/y.
Provide clarification of results and revise the total dose listed in Table 6-19, as appropriate.
Response
Table 6-19 contains a misplaced decimal point in the total dose listed for 50 years following license termination. Table 6-19 in the LTP will be revised to list the total dose listed for 50 years following license termination as 1.15E+01 mrem/y in response to RAI No. 33 below.
- 32. DTBD-05-001, "Comparison of Dose Impacts from Alternative Scenarios,"
section 6.3.3 The "drinking water intake" parameter is listed as sensitive for the resident farmer scenario for discounted radionuclides. In the LTP, page 6-42, section 6.8.2.3.2, instead of the "drinking water intake" being identified as a sensitive parameter, the "depth of soil mixing layer" parameter is identified as sensitive. The sensitivity analysis provided for NRC review demonstrates that the "depth of soil mixing layer" parameter is sensitive and the "drinking water intake" parameter is insensitive. The assigned value for the "depth of soil mixing layer" parameter based on the sensitivity analysis is used as the input into the mathematical model to calculate dose.
Provide clarification on identifying the "drinking water intake" parameter as sensitive in the supporting documentation (DTBD-05-001).
Response
The DTBD-05-001 sensitivity analysis for discounted radionuclides was performed using two RESRAD calculations, one for transuranic discounted radionuclides and another for non-transuranic discounted radionuclides. Excerpts from the RESRAD output reports showing the sensitivity analysis results are provided in Attachment 8.12 of DTBD-05-001. The results included in Attachment 8.12 indicate that the parameter ranked number 6 for the transuranic discounted radionuclides is depth of soil mixing layer. The text in Section 6.3.3 of DTBD-05-001 incorrectly lists the parameter ranked number 6 for the transuranic discounted radionuclides as drinking water intake.
The results from Attachment 8.12 are summarized in Attachment 8.10, which also lists the assigned conservative deterministic parameter value used for dose calculations. .10 indicates that drinking water intake is not a sensitive parameter and that it was treated probabilistically in the dose calculation. Attachment 8.10 also indicates that depth of soil mixing layer is a sensitive parameter and that it was treated deterministically in the dose calculation using a conservative parameter value. The November 20, 2006 Page 22 of 31
Response to RAIs Dated October 24, 2006 RESRAD parameter input reports contained in Attachment 8.13 confirm that this was the case.
Revision of the LTP is not warranted in response to this RAI; however, DTBD-05-001 will be revised to correctly list the parameter ranked number 6 for the transuranic discounted radionuclides as depth of soil mixing layer.
- 33. LTP, section 6.8.2.3.2 and Appendix 6-Z and DTBD-05-001, section 6.3.3 Under the resident farmer scenario for discounted radionuclides, the "contaminated zone erosion rate" parameter is identified as sensitive in the LTP, section 6.8.2.3.2 as well as in the DTBD-05-001, section 6.3.3. The assigned value of 7.59E-4 m/y was used in the site-specific mathematical model for the contaminated zone erosion rate but for only the transuranics (electronic file DiscNuc RF Dosel. RAD). However, for the non-transuranics, the default value of 1.OE-03 m/y was used as input into the model (electronic file DiscNuc RF Dose2. RAD). Appendix 6-Z of the LTP lists the assigned values for sensitive parameters to be used in the site-specific mathematical model. The "contaminated zone erosion rate" assigned parameter value of 7.59E-4 m/y is listed in Appendix 6-Z.
Provide justification for using the default value for the contaminated zone erosion rate parameter for the non-transuranics when the parameter is clearly identified as sensitive in the sensitivity analysis. As appropriate, provide the revised DCF and DCGL values for this scenario.
Response
Use of the default value for the contaminated zone erosion rate parameter for the non-transuranics cannot be justified. RESRAD calculations were recalculated by treating the parameter "contaminated zone erosion rate" probabilistically for transuranic radionuclides and deterministically for non-transuranic radionuclides as discussed below. The evaluation of the resident farmer alternative scenario presented in Section 6.8.2 of the LTP is conservative compared to the recalculations.
The potential dose calculations in DTBD-05-001 should have used the statistical parameter distribution for transuranics and the assigned value of 7.59E-4 m/y for non-transuranics as discussed below. Even though the default value for the "contaminated zone erosion rate" parameter is shown as used for the non-transuranics deterministic calculation, it was not used in the probabilistic calculation because the statistical parameter distribution had been provided for the "contaminated zone erosion rate."
DTBD-05-001, Section 6.3.3, identifies that the parameter "contaminated zone erosion rate" is sensitive for non-transuranic radionuclides but not for transuranic radionuclides.
This level of detail was not provided in Section 6.8.2.3.2 of the LTP. Instead the sensitive parameters listed in Section 6.8.2.3.2 are the parameters that are sensitive for November 20, 2006 Page 23 of 31
Response to RAIs Dated October 24, 2006 either transuranic radionuclides or non-transuranic radionuclides or for both. The sensitive parameter values listed in Attachment 8.10 of DTBD-05-001 and Appendix 6-Z of the LTP are also the parameters that are sensitive for either transuranic radionuclides or non-transuranic radionuclides or for both.
When potential dose from discounted radionuclides was calculated in DTBD-05-001, the parameter "contaminated zone erosion rate" was incorrectly treated deterministically for transuranic radionuclides (electronic file DiscNuc RF Dosel.RAD) using the conservative deterministic parameter value listed in Attachment 8.10 of DTBD-05-001 and incorrectly treated probabilistically for non-transuranic radionuclides (electronic file DiscNuc RF Dose2.RAD) using the statistical distribution listed in Attachment 8.10 of DTBD-05-001 as shown in the RESRAD summary reports provided in Attachment 8.13 of DTBD-05-001. The parameter "contaminated zone erosion rate" should have been treated probabilistically for transuranic radionuclides and deterministically for non-transuranic radionuclides.
DiscNuc RF Dosel.RAD and DiscNuc RF Dose2.RAD were recalculated by treating the parameter "contaminated zone erosion rate" probabilistically for transuranic radionuclides and deterministically for non-transuranic radionuclides using the assigned value of 7.59E-4 m/y. The resulting potential dose from discounted radionuclides was lower than that reported in LTP Table 6.19 for up to 100 years following license termination. The resulting potential dose from discounted radionuclides from 100 to 1,000 years following license termination was slightly higher than that reported in LTP Table 6-19 but the total dose for this period was still well below 25 mrem/y.
Section 6.8.2 of the LTP and DTBD-05-001 will be revised to provide the DCF and DCGL values resulting from these recalculations.
Containment Buildinq DCGLs
- 34. DTBD-05-007 "Containment Building DCGLs" The DTBD-05-007 "Containment Building DCGLs," is not referenced in the LTP.
Suggest adding this reference since it provides the derivation of the DCGLs for the containment building.
Response
The LTP will be revised to list DTBD-05-007, "Containment Building DCGLs," as a reference for Section 6.6.5.
November 20, 2006 Page 24 of 31
Response to RAIs Dated October 24, 2006
- 35. Page 6-32 of the LTP, Table 6-12 and Table 6-2 of the DTBD-05-007 Page 6-32 of the LTP, Table 6-12 lists the DCF and DCGLs for the renovation/demolition scenario for the containment building. Table 6-2 of the DTBD-05-007 also lists the DCF and DCGLs values for the containment building.
The DCF and DCGL values in these two tables should be the same for all radionuclides listed for consistency and clarification purposes. Some of the DCGL values appear to be slightly different due to numerical rounding in the presentation of results. The DCGL values are different for the following radionuclides: Na-22, Co-60, Sr-90, Tc-99, Sb-125, Cs-134, Cs-137, Eu-152, Eu-154, Eu-155, Np-237.
Provide justification for the differences in the DCGL values in the two tables.
Provide the revised DCF and DCGLs for the containment building as appropriate.
Response
The DCF and DCGL values in Table 6-2 of DTBD-05-007 are the correct values.
Table 6-12 of the LTP will be revised to match Table 6-2 of DTBD-05-007.
November 20, 2006 Page 25 of 31
Response to RAIs Dated October 24, 2006 Hydrology Issues 36.3 Page 2-25, Section 2.2.1.1 Initial Site Investigation For soil boring DH-23, please provide a boring log including geologic formation, their depths and the total depth of the soil boring DH-23.
Response
The boring log including geologic formation, their depths and the total depth of the soil boring DH-23 was first provided to the NRC as part of the information contained in Appendix 2C, Geology and Seismology, to the Rancho Seco Nuclear Generating Station Unit No. 1 Preliminary Safety Analysis Report. This information was carried through various licensing document changes and now exists as Appendix 2C to the Updated Safety Analysis Report.
The "Rancho Seco Nuclear Generating Station, Unit No. 1, Updated Final Safety Analysis Report" will be added as a reference for LTP Section 2.2.1.1. The boring log for DH-23 is provided as Attachment 1 to this RAI response.
- 37. Page 2-25, Section 2.2.1.2 Geotechnical Investigation for Proposed Evaporation Ponds Please provide geologic cross-section(s) showing the subsurface geologic features and the groundwater level(s) indicating the hydraulic gradient(s).
Response
"Geotechnical Investigation for Proposed Evaporation Ponds," ERPT-C0104, Rev.1, 1989 will be provided to the NRC. The report contains geologic cross-section(s) showing the subsurface geologic features and the groundwater level(s) indicating the hydraulic gradient(s). The geologic cross-section(s) (Figures 4, 5, and 6) from ERPT-C0104, Rev.1 are provided as Attachment 2 to this RAI response.
Revision of the LTP is not warranted in response to this RAI.
- 38. Page 2-26, Section 2.2.1.3 2005 Update Investigation Please provide drilling logs and construction details for the selected soil borings and monitoring wells.
3 The numbering of the "Hydrology Issues" RAIs has been revised to continue the numbering sequence used for the "DCGL Issues" RAIs November 20, 2006 Page 26 of 31
Response to RAIs Dated October 24, 2006 Is it correct to assume that the chosen depth intervals of the screens for each well were separated by at least 35 feet? The word 'feet' is missing after the number 35 and it may be corrected.
Response
Reference 2-19 of the LTP, URS Corporation, "Hydrogeological Characterization of the Rancho Seco Nuclear Generating Station," March 2006 (Hydrogeological Characterization Report), contains the drilling logs and construction details for the new monitoring well borings (MW1A-1C, MW1D, MW2A-2C, MW3A-3C, and MW4A-4C).
The Hydrogeological Characterization Report was provided to the NRC by letter dated March 15, 2006. Drilling logs and construction details for OW-2 and OW-3 are contained in the Geotechnical Investigation for Proposed Evaporation Ponds report addressed in the response to RAI No. 37 above. Drilling logs and construction details for SW-1 and SW-2 are not available.
Depth intervals of the screens for each new monitoring well are provided in Table 2-6 of the LTP. The depth intervals of the screens for the new monitoring well nests exceed 35 feet.
The word 'feet' will be placed after the number 35 when the LTP is revised.
- 39. Page 2-27, Section 2.2.2.1 Geology In addition to describing the stratigraphy of the site, please provide geologic cross-sections and fence diagrams to better illustrate the subsurface geology and the geohydrologic parameters of the site.
Also, please provide geologic cross-section(s) indicating the subsurface geology for borings MW2, MW3, MW4, OW2 and OW3 (Page 2-28).
Response
Figure 2-4 of the Hydrogeological Characterization Report is a cross section illustrating the extent of hydrogeologic information with a three-dimensional perspective.
Figure 2-4 does not depict the geologic cross section in the vicinity of MW3; however, the boring log for MW3 is provided, in Appendix A of the Hydrogeological Characterization Report.
The Hydrogeological Characterization Report will be revised to include a new figure (Figure 2-5) to provide a fence diagram connecting the new monitoring wells, MW1 -
MW4. This new figure is included in Attachment 2 to this RAI response.
Fence diagrams for OW2 and OW3 are provided in Figure 5 of the Geotechnical (included in Attachment 2 to this RAI response) Investigation for Proposed Evaporation Ponds report addressed in the response to RAI No. 37 above.
November 20, 2006 Page 27 of 31
Response to RAIs Dated October 24, 2006 Revision of the'LTP is not warranted in response to this RAI.
- 40. Page 2-28, Section 2.2.2.2 Hydrology Please provide a map showing creeks, streams, rivers and other surface water drainage features along with flood elevations, flood and low flow values, and nearby flood gaging stations (also Section 8.5.4.1, Page 8-12).
Please provide 100-year flood plain map to support that the site would not be flooded during a 100-year storm event.
Response
Creeks, streams, rivers and other surface water drainage features along with flood elevations are shown on Figures 2-2 and 2-3 in the Hydrogeological Characterization Report. 100-year flood plain maps for the immediate areas surrounding the Rancho Seco site are shown on Figure 2-3. General 100-year flood area information for Sacramento County may be viewed at http://www.msa.saccounty.net/waterresources/floodready/FloodMap.pdf.
There are no gaging stations or any stream flow values within 9 miles of the Rancho Seco site. The closest gaging station to the Rancho Seco site is on Laguna Creek near Highway 99. The intersection of Laguna Creek and Highway 99 is shown on Figure 2-2 of the Hydrogeological Characterization Report. Runoff from the site drains into an un-named "No-Name" Creek, which in turn flows into Clay Creek. Clay Creek flows into Hadselville Creek. Hadselville Creek then flows into Laguna Creek south.
Revision of the LTP is not warranted in response to this RAI.
- 41. Page 2-28, Section 2.2.3 Hydrogeology Please provide a figure suitable geologic cross-section(s) showing the eleven (11) borings which penetrated the groundwater for the purpose of illustrating the aquifer formation. Please indicate groundwater elevations, flow directions, hydraulic gradients and other geohydrologic parameters.
Response
Geological information is not available for all eleven (11) borings which penetrated the groundwater. Figure 2-4, Geologic Cross Sections Rancho Seco NGS Site, will be revised (included in Attachment 3 to this RAI response) in the revised Hydrogeological Characterization Report to provide additional clarification. A new Figure 2-5 will also be added to provide a fence diagram connecting the new monitoring wells, MW1 - MW4.
Groundwater elevations and contours are provided in Figure 2-7; Potentiometric November 20, 2006 Page 28 of 31
Response to RAIs Dated October 24, 2006 Surface Map for Groundwater Beneath RSNGS, December 2005; and the groundwater flow direction is also provided on the new Figure 2-5 in the revised Hydrogeological Characterization Report. Hydraulic gradients and other geohydrologic parameters are also discussed in Section 2.4, Hydrogeology, in the revised Hydrogeological Characterization Report.
Revision of the LTP is not warranted in response to this RAI.
- 42. Page 2-29, Section 2.2.4.1, Groundwater Movement Please show the calculations including the parameters used for the hydraulic gradient value of 0.0028 feet per foot.
Likewise, please show the calculations including the parameters used for the vertical upward gradient of 0.0028 feet per foot (Page 2-30).
Please show the calculations including the parameters used for the estimated hydraulic conductivity values obtained from the laboratory hydraulic conductivity tests and in situ packer permeability tests (Page 2-30).
Response
The Hydrogeological Characterization Report will be revised to include the calculations requested by this RAI. The revised Hydrogeological Characterization Report will be submitted to the NRC upon completion.
The revised Hydrogeological Characterization Report will contain the following discussion:
Groundwater levels in the four new well nests suggest that there is one aquifer between the water table and 300 feet bgs, that the horizontal gradient is southwesterly, and the vertical hydraulic gradient is upward. A potentiometric surface map, constructed with data collected in the monitoring wells on December 6, 2005, is shown in Figure 2-7. Data collected in two subsequent events support the flow direction and gradient. The contours support the hypothesis of southwesterly gradient beneath RSNGS. The range of hydraulic gradients calculated from potentiometric data for the wells is 0.002 to 0.0033 feet per foot in all depth intervals. Only one potentiometric surface map was prepared because the data suggest that the horizontal gradients are similar in all depth intervals from 170 to 300 feet bgs (Table 2-1). Horizontal gradients were determined with water level depth information obtained in December 2005. Depth information for all wells was converted to elevation by subtracting the depth from survey elevations of the tops of casing of monitoring wells. Water level elevations from MW1 B, MW2B, MW3B, and MW4B were combined with data from OW2 and OW3, wells constructed in November 20, 2006 Page 29 of 31
Response to RAIs Dated October 24, 2006 1985, to develop a potentiometric surface map. The well screens in OW2 and OW3 are most similar to those in MW1 B, MW2B, MW3B, and MW4B.
The potentiometric surface map developed with the water level elevations was used to determine the direction and magnitude of the maximum gradient among the six well locations. It was determined that the water level elevation decreased 4.5 over a distance of 1610 feet between potentiometric contours; therefore,4.5 was divided by 1,610, yielding a gradient of 0.0028 foot per foot southwesterly for the B depth interval.
Horizontal gradients were roughly estimated from water elevation differences between MW1C and MW3C and between MW1C and MW4C without contours. Those gradients were within the same range as the "B" depth gradients, suggesting horizontal gradients are similar in all depth ranges beneath RSNGS.
Vertical gradients were determined only for the well nests constructed in 2005. Gradients were calculated with water level elevations obtained in December 2005, March 2006, and June 2006 for the following screen interval pairs: MW1 B and MW1 C, MW2A and MW2B, MW2B and MW2C, MW3A and MW3B, and MW3B and MW3C. The distance between the center of screens in the well nests were determined from the well construction logs. Then for each pair (for example, MW2A and MW2B) of water level elevations at a well nest, the absolute difference between the higher water elevation and the lower screen elevation was divided by the distance between the center of the screens. The result of the calculation is the magnitude of the vertical gradient. If the water elevation for the lower screen had a value less than the elevation for the upper screen, the gradient was designated "downward" and provided with a minus sign. If the elevation for the lower screen was greater than that for the upper screen, the gradient was designated "upward". The vertical gradient calculations for RSNGS well nests varied from 0.0057 foot per foot downward to 0.0056 foot per foot upward across all screen interval pairs.
Six gradients were downward and four upward between "A" and "B" depth interval well screens. Four gradients were downward and four upward between "B" and "C" depth interval wells screens. None of the well screen pairs had consistently upward or downward gradients over the seven-month period that measurements were collected. There is no evident upward or downward influence on gradients caused by the change in season between the first and last measurements. The vertical gradient data calculated for RSNGS well nests indicate that neither an upward or downward gradient prevails in the aquifer.
The in situ packer permeability tests referenced on Page 2-30 of the LTP were performed as part of the Geotechnical Investigation for Proposed Evaporation Ponds and discussed in the report provided in response to RAI No. 37. Table 4, Field Permeability Test Results, in the report summarizes the in situ packer permeability tests is included as Attachment 4 to this RAI response.
November 20, 2006 Page 30 of 31
Response to RAIs Dated October 24, 2006 Revision of the LTP is not warranted in response to this RAI.
- 43. Page 8-13, Section 8.5.4.2 Hydrogeology The last paragraph states that "... the permeability of the site soils result in infiltration rates (from several hundred to several thousand years) that effectively preclude any radiological impact on the aquifer or the closest well to the site by the facility". Please provide calculations or data from publications to support this statement.
Response
"Geotechnical Investigation for Proposed Evaporation Ponds," ERPT-C0104, Rev.1, 1989, Section 8.3, Analysis of Hypothetical Liner Failure, contains an analysis, including calculations, that supports this statement. As stated in the response to RAI No. 37 above, this report will be provided to the NRC. Section 8.3, Analysis of Hypothetical Liner Failure, from ERPT-C0104, Rev.1 is included as Attachment 5 to this RAI response.
Revision of the LTP is not warranted in response to this RAI.
November 20, 2006 Page 31 of 31
Attachment 1 Boring Log for DH-23
BECHTEL CORPORATION SHEET I O1F 16 GEOLOGIC LOG OF DRILL HOLE HOLENOp.i 23 PROJECT R*ANGd SZC,3 t7TCEiAR S':AXbAvlI ANGLE FROM HORIZ _0° BEARING LOCATIONtN247,:750 E 2,25E,l130 BEGUN 6-23-17 COMPLETED, 7-2i;-'K7 OVERBURDEN 3.0 DEPTH DRILLED INTO ROCK. 52-0' TOTAL D.PTH OF HOLE 602' ELEV. WATER TABLE + 3 4 , 5 ' NO, CORE BOXES 21 NO. SA.MPLES TAKEN 23 CORE RECOVERY (%) 78 FEET W,.2 MODEL & MAKE OF DRILL J'Y 22:
GROUND ELEV. +/-£1274 HOLE LOGGED BY NACtAY, '.X E.ST, DRILLER "t'AM3 '
NOTES O R SAMPLE DATA 1 CLASSIFICATION AND LEVLS, E. Q Z .. " PHYSICAL CONDITION TURN, CHARACTER OF 'T ' V.T DRILLING, ATE*L ,E-F~resh awater used for. U - -<..* 3-3,0' GPRAV~tL. (0M-CW')Dark circulation 0-10 ft rod brown, sanidy, ,4lty, Se ill. T.D. Ciftsrng clayey3 , cobbles to 8" to 4.8 ft 0 n1iT Set 6 ini. I.D. cagias 3.0'-19o2' SAND AND SLUT: (SM-to 5.0 -ft SP) Red brown to brown, very (Retrieved) fine to fine-grainrid sanda, Sac 4 in. I.D. caain8 NC with abhndIant variegated to 5.1 ft gravel 0 CIA.
170.
CORE BIT -r~0"'
Corroonce using drill-ing mud at 10 ft to - L (Quick-Gel 4- fresh NC, water) DIA, Easier drilling @ 13" 0 165-Gravel decreases below 13 ft 91T
'Where no core recov-cry, lichologic 15 descripciona derived NC U
from ditch samples O IA, 0
CORE LoTAwered 4 in.
casiag to 18.5 ft I.D.
ITSI L 59.2'-19.7' 21AVEL: (CM-CW)
- m 3~0 1g.7'-30,0' SILTSTOýiE: (nL) -
NXWL Red brown. scattered sand WIA and -ravei , firm, friable 155-SiT IfMAA o40 1o 25- Below .28', material is 20 PPLIT 8, (ML) Rud brown, clayey, scattered sand grains, firm, DOIA.O slightly to moderately 0 15i0-friible, locally indurated 50 N x WI.
Mud viscosity = 70 30- / Red brown, 30.0'-3,3,7I silcy, abtIndanc SAND*STONE: (.9i-SP) see/1000 cc pea gravel, soft-fi.rm TUN4G.
57 1105- 33.7'-40.0' ~T.LTS~t0NE: (ML) inner barrel not pro-:
perly latched 0 35
~ / Red brow., scattered sand 33.7'-40.0' SILTI*nNE: (ML) grains 1-,-,--,
U-1/4 Hole NOEIR 23 HoltsizeNCRX, CT. RANCH() SECQ
PROJE CT RJ*;,CIO 5EC6 SHEET 2 OF 16 HOLE ______
NOTES SAYPL E DATA ON WATER TAWLE - Z Z A LEVELS, WATER RE-
©CA3 * - PHYSICAL CONDITION DRILLING, ETC. j A L 4-04 140 -
O
- 0. of, 40 4ý0.0'-52.0' SANDSTODNE (SM4-SP)
Red broiwx, ve~ry f+/-iae to med-ium, Nvariegated grains, pre-135 -
-4 *..' domainantly quartz, silvy, firm, friable 4 XWL 130 -
Hole drift aagle 1i T UN&
,fro vertiaal @ 50' " CARR.
Pull 4" & 6" I.D.cas-ing, ream hola with 0 6-1/4" rock bit to -
125 - 52.0'-54.0' CLAEY SITSTONE:
52 Ft. t00 (ML) Red brown.,scattered tine Gradational contact - to coarse sand graifns, soft-CARII 55- firm, Wa.sive, locally plas-ticc, trace anhydrous opal 100 root replacoomonts 120.-
54.0'-81,7' SILTSTOLIE (141)
Red tbrol~m 1 1oeally gray, sca-CARII tter4ed coarss sand and pea gravel, firm, massive, local 100 vertical icrrgular fractures,
- 50 scalttired uneavan horizontal.
C. BIT sili~cic bhands, 1/32"1 to 1/16G" 3-.- thick, gradas to sli~htly 100 clayey silt at 75.3' 100 CAR&.70-100 105 C. BIT 77 M-0C~ 75 5-1/2", -- 1/4" .Hole No. DRi 23 Hole Site NX, RAN~CH(; SEC..ý Site
PROJECT -2,0110 SE10 IiOLE NO, PH 23 NOTES SNAPLE DATA ON WATER TABLE o Cl CLASSIFICATION AND LEVELS, WATERRE- >0 PHIIA CONDITION TURN, CHARACTER OF 7A . * . PYCACN O DRILLING, ETC. .
100 100-0 TUNG.
CARO to'RE 80-Li~hloogy based on 81'.71-9.bS SILT!11y SANDIY, 0 CLAYEY GRAVEL: (GM) g~ray, so=~
drill charactcaristics- T.C.ZCIL 95-and cuttin~gs 77'-971: b~rownI, gravel to 1-1/2".sub-angular to round 0 01A 89.8'-94.5' SILTY SAN4DSTONE:
CORE.
BIT (SN) Rod brown to browa, fin<
tO .medium-grained, massive, 5G 7 1.05. 90- firm, uaeven &ilicic bands SPLITr (to 1/2") and replacement SPOON fillings, local vugs to 1/8" 90- 94.5'-9372 SANDY SIhTSTONE:
MI' (ML) ar0'dn, _'qcatteredmei-grained sand, locil- vugs, OIA. 85 ajiticir root:rpacmns Fil BIT fri~ablej very firm,~ 11)"
Gr~dtio1~lConLtact sil1icic band at 98,1' 95- ý182'-100O.3' SILIY SANDSTONE:
I. (SIS) Brown, very fine-grained 0oo scattered silicic streaks~ anid DIA. 80" COAt. porkets, local~ vugs Drift angle 2-1I/4' BIT 100.3'-I09.8' SANDSTON.: (SP) fro~m vertc-El 01001o 1197 Cray, very finc-grained, poorly gzrade., clean, scat-tered vugs, manganose-staineý 100 75. massive, unconsolidated to firm, trace anhydrous opal, S IT --1 1' back.,fine-graiaedquart-105.. zitic sandstone at 104,4';
ftat-lying fractures 1/4" to 3/4" apart belo*w 105.4',
5200 100. OIA- 7D -icaZedus CORE 109.8'-110.6' CLAYEY SLT-ST09E SIT (ML) Gray, maasive, firvi, FlaSt lying contact-- I fiat lying fracture plat liyjfl :fracture _J _.J I . L Ll0.b'-119.4' SADSTON.E (SP) a,/; o 1 l* Gray to dark gray, very fine 100 g 'A 6a Co fine-grained, uncemented Bedding dipq 60 from- MI A to local moderate induration
'horizontal core axis.s some bed planes, mticaceous 4- ~1. 44 -~ - J ~j 44 Hole Size, 5 1/2", 6 VI11 Hal, t-40 D11 23 e:.PAŽ{1C11O SECO
PROJECT *A*CUC- SEO tOE NO. 2II 23 NOTES SAMPLE DATA 2 ON WATER TABLE -0 - C LEVELS, WATER RE- :- - CLASSIFICATION AND TEVELN, WATER OE- PIHYSICAL CONDITION DRILLING, ETC. j AM-Brown, rassive, f-ir ibclua IA, I
COP E
// 120.5', Sc4at-iered Coarse' si811d gvely~uoaoltntadto 1-1gtl ira, trace c lay Gradetot Q) 7E,4n, trace fie rained, -- t:d, light 5-5. W ý1 I -~ ,ý'cosolldatedto 100 o rA, modtratp-ly -fir,,;
CORE
", -IZ/,5' SAND AM GRAVEL:
Base of laguna Fm._
Top of 14e1rten Flm.
BIT
/ (0 -5?) Tan, gray,Ilighr. gray fine to vcoasa to light grayii ýra;vel and nd white
- 0-N-,
Bedding dips 17 fro horilzontal core axis- BIT TaTn to BýYne to ftna~raiod, o bgraded Contact dips 22 fron) well bech!-ýI unccmcned t~o horizontal1 coro i-xis- moderately; rades grdrae io0 DIA. very coarse aris~
OfT
-Z4 Mrin:aee~tJ~a d p rt ,
40.
100 OIA.
4:014 BIT Gradational contazt----q_
Irregular ccOýnact--f 1/ tr~rmis l black, i Sui)roud friablje to i, Poorly graded, abuatidont jo 115. 1405 q~uartz, trimc; mica, Wame- e Ta 013' rtoo DIA.
CORE air (MIL) Brown$ firm' trc-- rnica, 145 abundjant nsl ao~ tainfng DIA. 30. 142.0'-145.0' CtLAYEY I S t0o (ML.) Red brown, nosld-Drift anglo 3-l/4~ CORE ed to modeyately,s r, BIT oio vertical 1150' SLve ,slightly nlm 4 bvŽ-
coming sandy at 14'5' 5/2 OD 145.0'-161.3 STLTSTONE:( ML) 100 DIA. Brown to red hrowni, Thnly BIT sandy and clayey, im mat-,
SLv
................. I
ý-- I I *R HANO U14 223 Mo[e Size Site aXrXlO SECO
SEOF S~JC HANGJ{T PROJCT RCHO ECOHOLE NO. D11..23 NOTES SAM PLt DAT ON WATER TABLE 0 CLASZ AN LEVELS, WATER RE-. 05 - Go TURN, CHARACTER OF
-1 CLASSIFICATION AND VPIYSICAL CONDITION DRILLING, ETC. .
L61.3'-165.1' SANDSTONE;(SP)
I SW O0 Blackish brown, very fine to 20, t0o SIAT firtn-grained, poorly graded, clean, massive, abundant quartz, trace anhydrous opal root replacements, friable, DIA.C, slight to moderately cemen-15 ted 100 VA.
ia~
165A.'-165.01 SILTSTONE:(NL)
Col Bed brow.n, massive, iirm Ufl-166.0 '-168.31 SANDSTONE: (SP-GP)
Dark gray, v. fine to fine-10 grained at top with scattcered 5woa 0
Beddirg dips 15 from: I O00 CIA. medium to v.coarsa, pea gra-horizonttal core axis- CORE vel; grades to pea gravel at BIT1 15823'-IL7h.8 SILTSTONE. (ML)
'S Red brown, (Top ftoot im in-100 terlaced with wbita silicic 0 IA.I CoRae screaks arnd -banks) Firm, OIT locally friable, aangaaoee Stained, Scattered vugs Sea Level 0 175.8'-181.0' CLAYSTONE: (CL) I 100 01 A. Dark red brown,) silty,, Uncon-CORE Solidated to slightly firm, massive, grades to clayey silt at 161.0' i'8L'0'-190.8' SILTSTONF:
Rd brown, grading (ML) to Stay l00 DIA.
CORE .brown at 182.5', grading to gray throughtJight gray w*ith 18s_ local iron staining at 188.51 clayey, poorly to noderately indurated, mas sirvc,angana.se
-10 s treaks too
'CORE
/
I 190.8'196.3' SANDST0NE WITH BIT ,-.. ,~
SULTTONE INTERBDES: (SP-SM-bM) 194-~ Dark brown to bla.ck sanla-stone, light 8ray si~tstone; Joint dips. 30 from. -15. Srades to medium grains at 100 196.3', poor to Indistinct horizontal core axis- r/C E 014.~~i:
bed planes, manganese-staines friable-moderately indurated]
Hale Sis, 5-1/2", 6-1/4" Hole No. DH 23 Site RANCHO SECO
5HEETJLý Of 16 PROJECT RANCijO SECO HO~LE No, DH 2-3 NOTES ON WATER TABLE CLASSIFICATION AND VO LEVELS, WAIER RE- PHYSICAL CONDITION TURN, CHARACTER OF 102F' 3o Iz DRILLING, ETC.
Drift angle 4-1/4o ~96.3'-231.0' SANDrJY SITS1h031.
0IA.
from vertical @200' CORE (Mi) Light brown, slightly GO SIT cl1ayey, trace bed planeý .1t cotrace iron oxide stairtS, Hole reamed to 6-1/4'1 trac e manganese from 4.8 ft to 201.0:
1't Fron 201 ft to 250 ft, lithologv deter-nined -
fron drill returns,__
drill chnroctcristics- Gray to black, fine to scat-and geophvyical l~s - tered meditio sand grains BIT from 205.0' to 218.0' 205 to 218 drilled TO 218 to 224' - no discernible ruttings" returned to surface'.
slow drilling 224' to 232' drilled-e8a3y
.31h0-243.0' 5AIND COMGL0MEM'rE 232 to 240 consider - (GP) Gray to black, 6-lundaiit
,able rig vibration, coarse sand gr~fl.s bounce, and chatter KoICNG Mt 2 HoleSize 5-1/2", 6-1/4" at RMIC1H0 SECO
SHEET 7 OFJU PROJECT RANCG1O SE.Co lotE N(.. 2.
2_3 NOTES SAMPLE DATA TUVECS,CHAACTEROf TURN, WARERTRE-R Of 18 B 2 T I PHYSICAL CONDITION DRILLING, ETC. U zA 135
-60 240-240' to 250' drillto relatively eýSy o~
-65 - ~ 0* ~
243,0'-257.7' SANDSTO_** (SP) 245- Gray, very ftne to fine-grained, locadly silty massive, hard
- 70 Drift angle 3-1/2' fron vertical @250'_ 2 100 0IA. -75 corn; BIT 7- ý;*OD 21 72 61A. 1 Bedding dips 50 from* I COR 257.7'-310.0' SILTSTONE:
horizontal core axis
(ý4L-SZ -SP) Light gray, massive, firm, locally sandy From 260 ft. to and intrbAddod with light 310 ft. lithology gray, very fine to fine-determined from -8B5
.'-.--~ ~-
grained, scattered VRdium, drill returns, drilll 614Cc poorly graded, mroderately
-7 charactetestics and ROCN hard sandstone
$IT 265-geophysical logs TO N;io&
-90 2 74-
-95 270
& .... ~.1 - A.- h '... & ~ L- A~
HoleiNo. DME23 Hole Siuz 5-1/2". 6- 1/4..
Site RA1iCIH0 SECO
SHEET $ OF j.6 PROJECT 'RNCHO SECO HOLE NO. D1I 23 NOTES ON WA'TER TABLE f ,
SAMPLE DATA a
ON WAE TAL =z CLASSIFICATION AND LEVELS, WATER RE- O , PHYSICAL CONDITION DRILLING, ETC.
-100-2&.0-:
-105-
-110-29-95 I.
-120-Drift angle 2-1/4*
from vertical cQ30W-2
-S.
I
-125" 3OI
-130-3 15 I 2~ 4-4 Bedding dips 30 from,-
3lo.o0-545.5' SADST0NFý (8P) horizontal core axis-Ligit gray, very fine to fin(
100 01A.
-135 315-grainted, scattered nmediuia, BIT poorly graded, moderately he rd 1, -ý ý Hole Size 5 112,11 6 1/4" holeSize~kj~ii..h~leNoDH 23 Site fANdHO0 s Co
SHEET 9__ OF _b_
HOLE NO. URH2-3 NOTES ON WATER TABLE 0 CLASSIFICATION AND LEVELS, WATER RE- U PHYSICAL CONDITION TURN, CHARACTER Of DRILL.NG, ETC, From 315 ft. to 365 ft., lithology determined by driLl returns, drill cr=* it t~a and geopbysical logs Drift ankle 1-1/2r from vertical @350' Base of Mulachen Form-L'ep of V-511ey SprIngET ie5-112"t 6-1/4" Ha' . Hole No.-- -
C~ RANCHiO SEGO a
PROJECT RANCHO SECO SKEET 10 OF AL6.
HOLE NO. D1 2 NOTES SAMPLE DATA L~VILJ WAER aRE aCLASSIRiCATION AND TUR~N, CHARACTER OF 0~ K 7 PHSCLCODTO DRILINGETC.v 354.0'-,365.0' SXLIST~ONE? (HL)
,180-
-185 365.-'-367.6' CLAYSTOrv0(CL)
Light brown to light 8ray, 100 DIA.
-190- highly fractured vertically COR E SIT and horizontally, firm V IIII III I a 367,6'-394,0' SUThSONE: (Kr.)
From 370 Ft. to 405 Light 8reen., firm to moder-Ft., 1Jithology deter- ately hard, inclusions of mined by drill re- - 144 00 angular fragnents oi similar tujrns, drill charac- - ROCK material, slightly, harder teristics, and geo- SIT TO 375-*
physical logs-40 0'
-200-38G-
-205-1 3aQ -
-210-39 .2 7
-215"
=
Hole No. DHl 23 Hole Sixe 5-1/2"1 6-1/4" Site RANCHO SEGO
PROJECT R O SEO OF .6 HOLE NO. DH 23 NOTES SAMPtE DATA .
ON WATER TABLERE- -2 z z LEVELS, w.AtEP LE0l WAERE 8* ** 5 * = o PHYSICA.LASi CAONANoNDITION TURN, CHARACTER OF MILuNG, ETC. . -SA IT 2 L
CLASSIFICATION AND 394.0'-406.5' GLAYSTONE: CHI)
Blue g-reen, highly plastic,
,220. fatty, hiph dry scrength, Drift angle i-3/4" from vertical @400' _
-225- 005-405--.
S'oD I.
I100 DI A,
-Z30 406.5-'-428.0' StLTSTONIE: (t4)
CORE Blue Sreenj firm to he--rd, BIT isaterlaced with $iLicic veirifets tO I"F thick From 410 ft to 460 ft-litho] ogy determined (ML-SM) Locally sandy telow by drIll returns, 410 Ft: very fine to ;fine dr ill ah~iar*=tuisttic7 6,/4, 00 -235 - grained, predominan~tly quart2 RCKI and otophysical logs BIT ro 460' 415--
-240-420-
-245.-
425--:
Q01
'-4
-m
'428.0'-439.0' CLAYST0INE? (CL-cu'
-255 mf 7 35 I
Holesize 5-112", 6-1/411 HoleNo. D1123 SieRAMXi[ SECO
SHiET OF PROJICT RA.NC1I0 SECO HOLE NO. DH 23 NOTES SAMPLE DATA ON WATER TABLE z0 CLASSIFICATION AND LEVELS, WATER RE- U z :
TURN, CHARACTER OF T - PHYSICAL CONDITION DRILLING, ETC.
EEO~i
~- .t 44(L 439.0' -513.0' CLAYSTONK AND SILT STONE (CTL-N L)
-265.
-270, 7
Drift angle 1-1/2' from v~ertic~al @450'2-
-275-441.:
Green, interbedded, firm to t00 hard, with rounded inclu-DIA, -285- siotts of like material CORtE B IT (ML-CL) 7t 5-:
From 465 ft to 515 ft.
litbology determiined' from drill returns, - 5'/4 OD -290-drill ch;ýT-.cteristiC3 BIT TO
-295-Hole Size 5-1/2", 6-1/4" Hole No. DH 23 RA~iI0 SECO
saiEET _L3~. of 16 HOLE No. DR 23 r
NOTES SAMPLE DAIA ON WATER TABLE CLASSIriCATION AND~
LEVELS, WATER RE- V U.
0 TURN, CHARACTER OF V IH2 PHYSICAL CONIT4fION DRILLING, ETC.
Claysoon* and saltstone as above (ML-CL)
ADrift angle 3/40 from varttca). @5O0t (NT.) W~hite to light gray, scattered 1/2" pabblts, clayey, hard vhe dry,
-trace anauxite?
HoIe Siza I" f -114" Hok, No. W~ 2-3 Site a.NrCIIO SECO
$1icT _Li4 oF 16~
-HOLE No. DF 23 NOTES ON WATER TAM.L LEVELS, WATER RE- CLAssiFICAT ION AND PHYSICAL CONDITION TURN, CHARACTER OF DRILLING, ETC.
From 520.2 ft. to 565 .3 ft.,Ii !a i~ogoy deterfafted fo drill recurru% drill characteristic S knd gzeophysical. log Ct.AYSTONE (ý1-CT.) .ocal sandy Drift Ka[e size 5-1/211, 6-1/4" Site 1R1iC11ý )O
SHEET -- OFJ16 PROJECT RANC{0 SECO HOLE NO, 21LQ-ON NOTES WATER TABLE I --
SAMPLE z
2 DATA t oz CLASSIFICATION AND TURN, CHARACTER OF ILLING, EC.
I!
- C VPHYSICAL SAMPL.
CONDITION I - -
-380 560-i
-38$
7=
565-~
I..-565.0'-569.5' SANDSMXNE (SP~)
SLight oltvt greeni, venry fine.
100 -39'0 gri~a~n pomdeaorly hxat'd, v OORE grerabc-fiitt p~ry hrde,v I id 57 0- 569-51-593-01 SILT'STG-NE AND, From 570.3 ft. to BIT CLAkYST0NM (rZL-CL) 597 ft., litholog7 a
determined from drill, -343 rturns, drill cbar--
actoristics and geo-. ROCK physical logs BIT 597' 78
-400C
-41V 5 ,T (CL)
/ 593.0'-602.0' 0live greeD, ClAYSTONEU scattered sand grains, f irt H&e No. Liii 23 Ho4es,,xe mote Size 11211 -66 1/4" 55 l/2' 1 Site PaUFCHO s1rC0
SHEET 16 OF..16 PROJECT RAMM HOLE NO. .J23 HS NOTES SAMPLE DATA ON WATER TABLE .i z LEVELS, LEEL, WATER RE-R 1 9 CLASSIFICATION AND TRN.*, CATER C.AR:CTER O.f #: 3 *_ "? . PHYSICAL CONDITION DZILLING, ETC.
595-420-Drift angle 1/2'0V**1C from vertical 0600' D4A, 6100 CORE 60 BIt Bottom of hole 602 ft NOTE 1. GEOPHYSICkL LOGS:
1ndu~cioa - Electric Lag SNP Neutron Log SoniC Log (With Hole Caliper)
Formation Density LoB Directional Survey NOTE 2. PU14P TEST:
Water Table: 143 ft Set A inch 113 casing at 318 ft Produced 48 gpm (av.) dvrLng 24 hr test with 10 ft (av.)
Utradown NOTE 3. PIEZOMPUER LNSTALIATION:
Installed 180 ft of 1-1/8 in. ID P.V.C. pipe with .95 ft stickup above covtr plate. The bottom 13 ft was perforated.
Static water level, upon completion of piezorneter installation.,
was 145.39 ft below the cover plate.
maoisizo .5-1-12" 6-1/4, Hole No. o.3
Attachment 2 Geologic Cross-Section(s)
.me Mwi_
MW3 MW2
- om to eiW A
3ýý B-1 B-2 0-9
-.!EGEND
] Clayey sand (SC-SM)
Grovel and Cobbtos with clay and silt (GC-GMI
~ Clay and modertlely
- t. highty plastc sandy silt. (CL-ML--'¶Ht umil Clayey sand (SC) o 5O 100 1%0 7W0 FIGURE 4 HORIZONTAL Sr.ALE I" - ?00" FENCE DtAGRAM-SOILS BORINGS
OW-3 OW-I LEGEND
~Riverbank FM (Plcistocene)
Launa FM (Pliocene) silIt s
........... _______ td s iIy sa nds, e&cr and clays Mielrten FM (M iocene)
OW-2
....... [ncJ ~~pT~o and silty sanids w/some gfavul.
V. Water Levels as of 110-15-86j X.;,
VElTI4eAt SCAL14 1" 100#
(
oG100 71Iszoo C,
FIGURE 5 H011 IZONTAL SCALE I'- MIV SCHEMATIC GEOLOGIC FENCE DIAGRAM
IOC FA#iNCE RMaAP pRIOpGOTY
' L INE'J
()EVAPOrflATI(ON PONO mAONOTOF1ING WEtLL
- UINUSEiD WATE~R tL
~ATEIR W LE=VIF1AXNTOUIn.
DASHED INHERE 1t4F~dREP CONTOUfl INT15iIVAL 2 FEET ALL woe Iii VATKNIM AnE tlELATIVE TO MEAN SCA LEVEI I
A I ~ ~ K ~~ 2~000 FIGURE 6 SITE WATER LEVELS OCTOBER 7-9, 1985
Attachment 3 Figure 2-4, Geologic Cross Sections Rancho Seco NGS Site, from the Revised Hydrogeological Characterization Report
A It' lml A21n AM-* A I1 ,O = .1 wutwd wmo.0 Ix a 1.
lIft-Wut D"J ARtMI U6 OWta Foim 2-4 omaoloccroi Sodeum I R rchoSc. NOS Ut.
Attachment 4 Field Permeability Test Results from ERPT-C0104, Rev.1
Table 4 Field Permeability Test Rgslat Page 1 of 3 interval Test Prezsure Borahoe ret Interval It Ve-ei Test PeBreability Lenxth (Ft) of 'Water OW-I 53.1-61.0 7,9 Couldn't seat packers 90.0-99.1 9,1 97.7 Packer-Constant 2.3, x 10-6 Read 126.8-135,1 q.1 152.4 Vaýr.-Coviotant No TXake head 126.8-135.9 9.1 165.6 packer-Gonstant No Take Head 9,1 191.6 Packer-Constant No TAke Head 146 8-155.9 9.1 153.2, Packe7-CoQnStaunt 2., x 10-6 Head 166,5-200 33.5 160.6 4,7 x 10-56 166.5-200 33,5 175.5 166.5-200 a3.5 189.3; 5,5 x 10-5 166 .5-2OO 33.5 175.5 5.5 x 10-5 167.7-ZB7.,8 20.1 5 )c 10-6 Sailer-Recovery 167.7 110.2 Paeker-Constnt 6,.9 x 10-7 Head 67-79,5 10.5 96.7 Packer-Constant No Take Head 6g~79,5 10.5 112. B Packer-Constant, No Take Head 100-110.5 10,5 128.7 Packer-Constant No Take 1oo-.110 .5 10.5 144.8 Head Packer-Constant No Take Head I00-11I0.5 10 5 181.6 PacrKer-Constant NG Take Head 114-119.7 5.7 178.0 Packer-Constant No Take Head 1124-119. 7 5.7 224.0 Packer-,Constant No Take Head 114-119.7 5.7 258.5 Packer-Constant No T-ke Head 114,5-156.3 41.5 183.9 Padker-Constarnt 3.1 x 10-6 Head 114,5-!56.3 41-8 206,9 Packer-Constant 3.1 x 10-7 Head 41.8 241. Packdr-Constant 4.1 x 10-6 Head 2453V/42
Table 4 Field Permeability Test ReSults (continued)
Page 2 of 3 Interval 'Test Test Pressure
-Borehole Tested Inte rval In 7eet Test Permeability Lemngt' (Ft) of Water method cm/sea OW-2 122.0-127.7 5°7 142.0 Packer-Constant No Take Head 122.0-127.3 5,7 165.0 Packor-Constant No Take
'Head 122.60-127.7 5.7 188.0 Packor-Constant go Take Head 122,0-127.7 5.7 2334.0 Packer-Constant No Take head 136.0-141.7 5.7 1.52.0 PakAr-Constant No Take lIe ad 136.0-141.7 5.7 175.0 Packer-CQR~stnt No Take Head 136.0-141.7 5,7 298.0 Packer-Constant No Take Re~ad 136.0-141.7 5.7 232.0 P~ackr ont~att Ho Take Read 146A0-151.7 5.7 164.0 Packtr-Constant No Take Read 146.0-151. 7 5,7 181.,8 Packer-Gonstant go Take Head 5.7 210.8 Packee-Constant No Take 146.0-151.7 Head 5.7 245.3 Packer-Constant No Take 148,5-159.0 Head 10.5 200. 9 Packer-Constant No Take 148.5-159.0 S10. Head 235 ,4 Packee -Constant No Take Head 148.5-159.0 10.5 267.6 Packer-Constant, No Take Head 149.5-160.0 10.5 197.6 Facker-CoQntant 1.1 x 10-4 Read 14'9.5-160. 0 10.5 232,11 Packer-Constant 271 x 10-5 Head 151.0-156.7 5.7 176 .0 Paeker-Constant No Take, Head 5.7 185.2Z Packer-Constant NO TaKke Head 151.0-156.7 5.1 196.7 Pacler-Constant No Take Hioad 151,0-ISS.7 5.7 219, 7 Packeo-Constant Vo, Take Head 151.5-162.0 230,i Couldn't Seat Packers 153.0-174.0 21 Specifiec 2 10*3*
CapaCity 2453V143
lable 4, Field Pe~rmsability 7est Remalt.z (~totinued)
Page 3 Df 3 Tnterval Tast Test Pressure Borthole Tes ted Iii Feet Test Permeability Lenz th *t A F L3-4+,m4 W %~A
-- - -. *"N~ *4i k't~..t ~.uAJ C OW-2 ~16:9 .5- 1 Sb. 0 221.6 Parckec-Cons tarnt 1.6 x 10-5 10.5 He~ad 279.1 1.5 x 10-5 Paeker-constant 10.5 274.1 1.5 x 10-5 He~ad
.2 30.2 Pac~ker-C ons tan t 2,7 X 10-6 116.5 115.0 lisad 1.5 x 10-6 r~cker-C onst-ant 52.5 117.0 Haad 1.2 x 10-6 Packer-Cons tant 112.5-164,0 51.5 126.9 Head No Take Patkar-Conj tant 138.4 ýMead No Take 112.5-164.0 51245 Pack~er-Constanft 152.2 'Head No Take 168.03-192.9 24.°9 Specif ic 8 x I0-K*
Capacity P~1 9,25-9,50 9,25 Perme ameter 1,6 x 10-5 P-2 01a47-9,50 9.03 Permearet~er 1.9 K 10-5 P-3 0,36_9.50 9.14 Pe-iftearneLe r 6.0 K F-3 0.25-9.50 9.25 Fermeaseter 1.8 X 10-4
- Testvas on~du~tlbd pr'ior to completion of well develIopment.
- Pemeailiissara for sand zones only.
2 45 3V /*44 245~~Vr An / 44Irj i'r r~r
Attachment 5 Analysis of Hypothetical Liner Failure from ERPT-C0104, Rev.1
is the e+/-ffective or inte~rconne.tt~ad porosity. Using an avera:&e hydraulic cnuctivi.tyi for the G-*d of I x 103cM/.c an estim~at~ed effective porosity of 30% and the obs~erved hydraulic gradient of 0.fl03, the A-PproXina~te seepage v~elocity is 0,028 ft/day or about 1'0 ft/yr.
8.3 Analysis of Hyp~othet~ical Linar Fa~1um, An analysis was perforned to evaluate the effects of a hypothetical pond tiriert failure on the qualit~y of ground wator dowhgradient of the site. The nearest dowgradiont well is 618-1091, on the north side of Clay East. Road, about 2200 feet, west of the west edge: of the evaporation~ ponds. It was ass-um~ed that the liner is~ breaathd at. the end of the pond life. wbeili Cs-137 Is expected to be at a toncentration of 8-5 x~ 10- 2 Cilrrl as a result of Ovapo rationi.
The. aftaly~is considered migratilon of Cu-137 t~o weil 6/8-30Q1 in two otoges.
Thq first stage is vertical seepage of pond fl~.iid to the underlying water table. The second sta,&e is horizontal mrniration In the Mehrtan aquifer from tba pond site to the well.
Stage 1 For seepage through Itbe unsaiturated zone to the vrater table, the method of Bouver for vertical m~ovement of a wetting front (1978, V. 254) was us:01.
The appropriate equation is.-
0 (~Lf Hc~b
+ - h 2453V/33 I---
where :
t' timn since start of infiltration X = hydraulic conductivity of wettod zone funsaturafed u
conductivity)
L = depth of wetted front w depth of water above soil h = critical pressure bead of soil for wetting C.
f = fillatle porosity (difference between volumetric water conteot of soil before and after wettint).
Conservative input values were selected for calculating the time it would take for a watting front to reach the water table. For KU (unsaturated conductivity), a value 0f half tht saturated hydraulic conductivity was used (Bouwer, 19V8, p, 253). For the material above the water table, a saturated conductivity of 3 x 10 cm/sec is believed to be reprosentative, based on packer test results (See Table 4). This gives a value for K of 1,5 x u
-6 10 cmlsec, or 1.55 ft/yr.
L f is the depth to the wetting front from the bottom of the pond excavation. This depth is variable durinr seepage from the pond, but would be a minimum of about 144 feet When the front reaches the water table. The heigbt of water above the soil CHW) was assumed to be seven feet, which is w
the maxima, upeiratin; depth of five feet, plus two feet for the clay liner thickness. The averare critical pressure helad was estimated to be about
-100 cm (-3.3 ft), based on typical values for fino-Srained soils reported in Bouwer (1978, p. 243).
The fillable porosity is a difficult parameter to estimate, as it would vary considerably from one type of soil to another, and is dapendent on the in-place volwuetric water content. On tho basis of limited 8Dils 2453V/rf34,
tes.3o~n'Sr,,,~V~e value of ten perc~ent (0-10) was used Ivor t~he UJsir.g the input -data 8eacribaed above, tim~e for a wetting front to reac.b the &r'ound water~ iG appr~oximatel.y 8 ye-ars. w~evar, becauss of C-s-137 adsorption onto the soils particles as the wattirp, ifront rnovss downw-ard.,
the tima of arr~ival. of radionuclides at the water table will be much longer-. Applying a retardation factor of 0.005 (see de~mripticn of Stage 2 scopage) t-o the averure velocity of th4 wettin& front 144 ftJ8 yrs gives an average estimated Cs-137 velocity of 0.09 ft/yc. At this rate it wtould take 1600 yearz for C9-137 to reach the watCer tabl~e. During this period of time, the cntntcation wmiuld be reduc~ed by radioactive decay to less than 10-1 VCifal.
The iaetbod of analysis if or mi~ration oif Cc-l137 in grou-nd water frowm the pund to the nearest duEwrigrdient w'ell is based on thea following relaltionsNhips (Gr'ove, p. 28),
U. U R 2.0n -water if n
and C CO e xt.
2453V/35
velocity of Ca-137 groun-watec seepag-S velocity retardation fac~tor p = buklk density n = distri~bution coefficiont concenitration at time t CO initial corcen+ttabion t = travel time, radio-active 'davay coniz.ant The ground water seepa&e velocity, U~e is determriined by tho Dar-cy relationship:
Uwater= 11 wbere-:
K bydraulic conduc~tivlty I hydraulic gradierat = .003 Ef./ft ftom Figure 6 no .effeetive porosity, assurned 1Lo b~e .30 A hydraulic tonduc~tivity of 2 x 103 cr4U~stac (2069 ft/yr) -- thie higbest value fr-om field tests tsee Table 4) -- wa~s used for- calculation, of Uwater 1Eyr
'To determkine X, 9a value of 4 &/c wat us5ed for p/ti, arpd 50 ml/g vas used for the distr-itution coefficient, K These values are believed to be conservaluive based on data reported in the literature. Using~ the described itput data, R = 0.005, and V oU ý 21 ft/day x .005 = 011 ftlyr. A'- thi-s rate of rnove-muant,1 It will take 20.000 years for Cs-'-37 to travel to Wall 6/8-3001. After this period of time, the calculatod 245 3V/ 36 ________
coilce7ntrtion of Cs-137, redu~ed by radioac':,ivv deicay, is less 1than 10-9 OCVi/a, nondotect~kble loval. It i~s well balow ih 10C (mx~rtZim
-P-N~isitl tacentati 2 10 uCi/mi u-nder 10 CYR 20, A?ppondixc B, TablG* II.
9.0 Grgn W~ater Monit~zrinA Program To ansure that there is no 1eakate of' effluen~t from the ponds and to compl1y with Re~iconal Water quality Co.ritro1l Board (RWQC5) re~ulatlons, the foliow-ing ground water tro-it~oitg progv=r Is propogd. Four~ ground wat~er mionitori,rng wolls located at the periimeter of the pond will be mrv~itov-ed on a qua.-terly basis for the parameters listsd in Table 7, la addition, .lygimeterg or other vadote zone monltorinr, davices adjacmnt to the -ptnd~s will be, sampled quarterly to dget~mine the cheakcal c-ompositioen of tho soil 7,ore water and ensure that no leachate is oscaping into the unsaturated Zone. The vadose zone muonitoring, ho~wever, is not requir'ed ky the R6WQC'B for thit-! project. Water rsapl~t ofE the ponds will also be collooted month~ly and analyzed f'or the paramneters listed in Table 7.
24S3V/3,7 LDA[-'I:A