ML071000434

Response to NRC Request for Additional Information

ML071000434
Person / Time
Site:	Rancho Seco
Issue date:	04/02/2007
From:	Redeker S Sacramento Municipal Utility District (SMUD)
To:	Document Control Desk, NRC/FSME
References
MPC&D 07-028
Download: ML071000434 (62)

Text

SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT The Power To Do More.m r

P.O. Box 15830, Sacramento, CA 95852-1830; 1-888-742-SMUD (7683)

MPC&D 07-028 April 2, 2007 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 February 27, 2007, you requested additional information required to complete the NRC's review and approval of the Rancho Seco License Termination Plan (LTP) and associated environmental assessment. 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.

aSinceI.

Steve Re er Manag, lant Closure & Decommissioning Attachment Cc w/ attachment: B.S. Mallett, NRC, Region IV P raý60 (

RANCHO SECO NUCLEAR PLANT - 14440 Twin Cities Road, Herald,CA 95638-9799; (209) 333-2935

Response to RAIs Dated February 27, 2007 ENVIRONMENTAL ISSUES

1. Section 8.6.3.13, Aesthetics Issues, states that the District intends on leaving the major concrete plant structures in place after the completion of decommissioning and license termination. It is understood that temporary structures will be dismantled and removed.

a. Please describe any plans for restoration, re-vegetation, and other permanent environmental measures (e.g., erosion controls) at the site (e.g., areas of the site where temporary structures will be dismantled and removed).

Response

In most cases, concrete floor slabs are abandoned in place as building structures are dismantled. In rare instances where erosion issues may be created by building dismantlement, asphalt paving, gravel, or re-seeding with native grasses will be used to prevent erosion.

An example of concrete floor slabs abandoned in place from dismantled structure is shown in the following before and after photographs.

April 2, 2007 Page 1 of 61

Response to RAIs Dated February 27, 2007 Before After Apd1l2, 2007 Page 2 of 31

Response to RAIs Dated February 27, 2007

b. Please describe the approximate acreage of the site occupied by infrastructure (e.g., buildings, roads, parking lots) prior to decommissioning and what that acreage would be after the site is released from NRC licensing.

Response

The acreage of the site occupied by infrastructure (e.g., buildings, roads, parking lots) will not change after the site is released from NRC licensing. The majority of the infrastructure is contained within the existing 87-acre Industrial Area. The only.

exceptions are the Hazardous Material Warehouse, the Receiving Warehouse and portions of the paved site access road. The Hazardous Material Warehouse will be demolished down to its concrete pad prior to completion of the first phase of license termination. The fence enclosing the Industrial Area will not be removed during decommissioning. Upon completion of the first phase of license termination the Industrial Area will be maintained as an industrial site with access controlled by the SMUD Asset Protection'Department (industrial security). The Interim Onsite Storage Building (IOSB), which will remain under the 10 CFR Part 50 license, will be contained within this industrial site. The Backup Control Center (BCC) in the former Administration Building, the Training and Records Building with occupied offices and the active switchyard will also be contained within this industrial site. The Independent Spent Fuel Storage Instillation (ISFSI), which is licensed under 10 CFR Part 72, is accessible only from the industrial site. No existing roads or parking lots will be removed during decommissioning. Upon completion of the second phase of license termination, access to the industrial site will continue to be controlled by the SMUD Asset Protection Department.

Before and after decommissioning aerial photographs of the Industrial Area are provided below.

April 2, 2007 Page 3 of 31

Response to RAIs Dated February 27, 2007 April 2, 2007 Page 4 of 61

Response to RAts Dated February 27, 2007 Apri 2, 2007 Page 5 of 61

Response to RAIs Dated February 27, 2007

c. Please identify potential environmental effects (e.g., on migratory birds and raptors) from the structures (e.g., hyperbolic cooling towers) that will remain in place after unrestricted release of the site or portions of the site. Include any related requirements that will need to be complied with after release of the site or portions of the site from NRC licensing (e.g., avian protection related acts).

Response

The environmental effects from the structures that will remain in place after unrestricted release of the site or portions of the site will be no different than the effects that existed during plant operation and the period of time following final plant shutdown and license termination. The remaining structures are large stationary objects that are readily observed by migratory birds and raptors and thus easily avoided. Removal of these structures would have a negative impact on the nesting of migratory swallows because large numbers of them build their mud nests on these structures.

The State of California is concerned about avian safety and has conducted numerous studies related bird fatalities caused by collision with overhead power lines and wind turbines used in the generation of electricity from wind power. However, they have not conducted studies of bird fatalities caused by collision with stationary structures. Also, the California Energy Commission has instituted an investigation into the development of statewide guidelines for reducing wildlife impacts from wind energy development.

d. Please provide a listing to clarify which specific structures will likely remain standing at the site after release from NRC licensing.

Response

Most of the major concrete structures will remain in place. All paved areas will remain paved. Below are "Structures Figure 1", showing the buildings located near the power block, and "Structures Figure 2", showing the remaining structures in the vicinity of the Industrial Area. A red "X" indicates that the structure has or is scheduled to be removed, leaving only the concrete pad of the structure for Final Status Survey. Note that the cooling towers and cooling tower basins will remain following License Termination. All planned structure demolition will occur before Final Status Surveys are complete for the first phase of the License Termination Plan (LTP).

April 2, 2007 Page 6 of 61

Response to RAIs Dated February 27, 2007 The following buildings shown in "Structures Figure 1" will remain after License Termination:

1. TDI Diesel Buildings

2. Back-up Control Center (formerly Administrative Building)

3. Training & Records Building

4. Nuclear Service Electrical Building

5. Auxiliary Building

6. Reactor Containment Building

7. Spent Fuel Building

8. Turbine Building

9. Switchyard Control Building

10. Machine Shop (includes area formerly known as the "A" Warehouse)

11. "B" Warehouse

12. Personnel Access Portal (PAP) Building April 2, 2007 Page 7 of 61

Response to RAls Dated February 27, 2007 The following buildings shown in "Structures Figure 2" will remain after License Termination:

13. ISFSI

14. Interim Onsite Storage Building

15. Receiving Warehouse

16. Unfinished Technical Support Building

2. Please summarize any changes that are planned for the site storm drain system and outfall discharge pipes, including the portions of the system that provide drainage from the switchyard and the Independent Spent Fuel Storage Installation (ISFSI).

Response

No changes are planned that will affect the storm drain outfall discharge pipes. Minor rerouting within the storm drain system will be required within the Industrial Area because of demolition activities but this rerouting will not affect the outfall discharge pipes. The switchyard is energized and being used by the Cosumnes Power Plant as discussed in Section 6.4.2.1 of the LTP. No changes have or are planned to be made to switchyard storm drain system. No changes will be made to the ISFSI storm drain system as a result of the 10 CFR Part 50 license termination.

April2, 2007 Page 8 of 61

Response to RAIs Dated February 27, 2007

3. Section 3.3.6.1, Deferred Activities, Storage of Class B and C Waste, states that it is the decision of the District management that acceptable waste disposal options for Class B and C waste do not exist at this time. Further, the waste will be stored in the IOSB until such time as an acceptable waste disposal site is available, when the waste will be shipped and the building will be decontaminated as required. Additionally, Section 8.3, Site Description After Unrestricted Release, states that the District intends to release the site for unrestricted use in two phases, with the majority of the site released in the first phase. The second phase is identified as release of the IOSB, which is indicated as remaining on the 10 CFR Part 50 license until the license is terminated with the unrestricted release of the IOSB.

a. Please confirm that the current maintenance and monitoring procedures used for the site include the IOSB, including physical and radiation monitoring of the facility and waste containers. Please specifically confirm that the IOSB is addressed in the current environmental monitoring, emergency, and security plans.

Response

Rancho Seco implements its maintenance program on an ongoing basis to ensure that plant equipment maintains its required level of performance. The maintenance program applies to both the 10 CFR Part 50 decommissioning site and the 10 CFR Part 72 licensed Independent Spent Fuel Storage Installation (ISFSI). The maintenance program will continue to be implemented as long as the IOSB is operational and spent nuclear fuel is stored at the ISFSI.

The Rancho Seco Radiation Protection Plan discusses the philosophies, policies, and objectives of the radiological controls program. Implemented by site technical and administrative procedures, the radiological controls program is designed to control radiation hazards, avoid accidental radiation exposures, prevent unauthorized access to radioactive material, and to maintain radiation dose to workers and the public below regulatory limits and As Low as Reasonably Achievable (ALARA). The radiological controls program is integrated into all radiological operations at Rancho Seco, including the IOSB.

The radiological controls program applies to both the 10 CFR Part 50 decommissioning site and 10 CFR Part 72 licensed ISFSI. The radiological controls program will continue to be implemented as long as there is licensed radioactive material at the Rancho Seco site.

Radioactive waste procedure RP.309.IV.01, "OS Building Operations" specifies the requirements for operational activities in the IOSB. This procedure addresses warehouse operations to ensure that stacking requirements are maintained and that dose rate limits are not exceeded. The procedure also addresses ventilation system operations, container handling and inspection requirements, and crane operations.

These procedural requirements will remain in effect as long as the IOSB is operational.

April 2, 2007 Page 9 of 61

Response to RAIs Dated February 27, 2007 The Rancho Seco Radiological Environmental Monitoring Program (REMP) is designed to meet applicable regulations and to provide an accurate assessment of the radiological environment in and around the environs of the Rancho Seco site. The REMP applies to both the 10 CFR Part 50 decommissioning site and 10 CFR Part 72 licensed ISFSI. The REMP will continue to be implemented as long as the spent nuclear fuel remains stored at the Rancho Seco ISFSI.

Similarly, the Rancho Seco Emergency Plan applies to both the 10 CFR Part 50 decommissioning site and the 10 CFR Part 72 ISFSI. As decommissioning progresses and the radiological source term is reduced, the emergency planning requirements may also be reduced without reducing the effectiveness of the plan. The emergency plan will remain in effect long as the spent nuclear fuel remains stored at the Rancho Seco ISFSI.

The Rancho Seco 10 CFR Part 50 licensed facility is exempt from 10 CFR Part 73 security requirements. Accordingly, the IOSB is not covered under an NRC-approved security plan. SMUD provides industrial security for the 10 CFR Part 50 site. SMUD management determines the level of security provided for the Rancho Seco Industrial Area.

b. Please identify the approximate area size and location of the fence line and gate for the portion of the site that will remain on the license with the IOSB and the relationship to the spent fuel storage area, including both the distances between the spent fuel and the IOSB fence lines. Also, indicate the location and expected readings for maximum radiation levels between the IOSB and spent fuel storage area. If the land between the spent fuel storage area and IOSB is not going to remain on the license, indicate the anticipated maximum radiation doses in this region where unrestricted release is occurring between the two fence lines and provide the analysis to assure that 10 CFR Part 20 public dose limits will not be exceeded (using dose contributions from the ISFSI, released area, and IOSB). Additionally, please identify these locations on a map or diagram.

Response

The figure "Proposed IOSB Fence" below shows the building footprint and relative locations of the bermed area, the boundary fence, the gates east of the IOSB and the approximate distances of the fence lines to the nearest portions of the building. The total footprint that the 10 CFR Part 50 licensed site will occupy after Phase 1 of License Termination is encompassed by the rectangular area within the fence, and is approximately 300-feet east-to-west by 160-feet north-to-south. The total area is approximately 1.1 acres.

April 2, 2007 Page 10 of 61

Response to RAIs Dated February 27, 2007 1/

Earth Berm Rip rap for erosion control, 5012, 1ý ILISB

- 0.5 f t-

-- 90 f-tI 70 iP-t I

paved f ILL -Pence North -,Fý The figure "Fence Lines" below indicates the approximate location of the fence line proposed for the IOSB (shown in blue) and the approximate location of the 100-meter fence that is in place around the ISFSI (in red). The green lines approximate the current outer portion of the industrial area fence that will remain in place. The purple line labeled "A" is the shortest distance between the IOSB and ISFSI fences, which is approximately 130 feet. Access to the area within the red lines is controlled by the 10 CFR Part 72 license. Access to the area within the blue lines will be controlled by the 10 CFR Part 50 License between Phase I and Phase II of License Termination.

April 2, 2007 Page 11 of 61

Response to RAIs Dated February 27, 2007 Radiation levels outside of the fence lines of both facilities are statistically not distinguishable from background. The Radiological Environmental Monitoring Program measures the long-term dose rates at locations around site, including around the perimeter of the ISFSI. Personnel dosimeters are placed on the 100-meter fence at the locations indicated with white numerals in the figure "Fence Lines" above. The tables below indicate the results of quarter-long monitoring with dose given in mRem/quarter.

Locations 1 through 6 refer to the locations in the figure. Locations C-1 through C-6 are "control" locations, away from the site, used to determine the local background radiation levels in the area.

Data for the years 1997, 1998, 2001, and 2006 are included. Fuel storage into the ISFSI commenced in 2001, and was completed in 2002. 1997 and 1998 provide indication of the levels in the area prior to placing fuel into the ISFSI. The last Class B and C waste to be stored in the IOSB was generated during the segmentation of the Reactor Vessel Internals. The project was complete and all the waste intended for storage between Phase I and Phase II was in storage in the IOSB by the end of the 2 nd quarter of 2006. Even though there is an apparent increase in the total dose received by the dosimeters at the ISFSl boundary compared to the dose of the control locations, Apdil2, 2007 Page 12 of 61

Response to RAIs Dated February 27, 2007 the difference remains statistically small. Mathematically, comparing the highest average indicator locations with the lowest average control locations in any given year results in a difference of 2.5 mrem/quarter or 10 mrem/year due to the ISFSI.

In 2006, after all waste intended for storage was actually in storage at the IOSB, surveys were performed outside the perimeter fence surrounding the IOSB using 2" X 2" Nal detectors. These surveys were conducted to determine if the waste in storage at the IOSB would interfere with the planned MARSSIM surveys of the surrounding areas for License Termination. The surveys indicated that the gamma field along the fence was the same as the gamma field measured in Class 3 areas that are shown through sampling and laboratory analysis to have no detectable contamination from plant origin.

Since the surveys, which indicated levels of 6,000 to 8,000 cpm, are no different than background in a Class 3 area, the dose consequences are not greater than that from a Class 3 soil survey unit. To date, no Class 3 soil survey units have indicated measurable contamination of plant origin above background. Therefore, it can be assumed that the dose resulting from occupancy in these areas would be less then 10%

of the 25 mrem/year allowed dose, or less than 2.5 mrem/year.

Since the land areas around the ISFSI are either non-impacted (North, West, South areas surrounding.the ISFSI), or Class 3 areas (East of ISFSI), worst case dose impact from residual radioactivity would be less than 10% of the annual limit, or 2.5 mrem/year.

Combined with a maximum 10 mrem/year from the ISFSI and 2.5 mrem/year from the IOSB, the resulting dose to an industrial worker occupying the land areas between these two facilities would be a maximum of 15 mrem/year, which is below the 25 mrem/year limit allowed for license termination.

Year 1997 Quarter Q1 Q2 Q3 Q4 Avg Location _

1 13.1 14.1 16.4 15.4 14.8 2 16.0 15 14.8 16.4 15.6 3 13.8 14.7 16.2 15.6 15.1 4 14.2 16.3 15.9 16.1 15.6 5 17.5 15.4 16.1 19 17.0 6 13.9 14.4 14.7 15.7 14.7 Qtr Avg 14.8 15.0 15.7 16.4 15.4 C-1 12.7 14.4 15.3 16.6 14.8 C-2 14.2 17.5 Note 1 21.1 17.6 C-3 11.7 12.6 15.5 15.8 13.9 C-4 12.7 15.3 14.1 14.8 14.2 C-5 11.0 13.9 14.2 13.9 13.3 C-6 13.7 14.4 14.7 16.7 14.9 Qtr Avg 12.7 14.7 14.8 16.5 14.8 April 2, 2007 Page 13 of 61

Response to RAIs Dated February 27, 2007 Year 1998 Quarter Q1 Q2 Q3 Q4 Avg Location 1 13.6 14.1 14.2 15.6 14.4 2 13.6 14.1 16.8 15.4 15.0 3 14.4 14.0 15.0 15.4 14.7 4 20.7 14.6 14.3 15.2 16.2 5 15.9 14.6 15.2 15.6 15.3 6 14.1 17.4 14.2 15.7 15.4 Qtr Avg 15.4 14.8 15.0 15.5 15.2 C-1 15.4 17.2 13.9 14.3 15.2 C-2 17.2 16.3 19.3 16.5 17.3 C-3 12.4 13.8 12.8 13.3 13.1 C-4 15.7 14.3 14.0 15.4 14.9 C-5 13.7 13.5 13.1 13.6 13.5 C-6 11.8 13.8 14.2 14.6 13.6 Qtr Avg 14.4 14.8 14.6 14.6 14.6 Year 2001 Quarter Q1 Q2 Q3 Q4 Avg Location 1 17.0 15.0 15.0 14.0 15.3 2 17.0 18.0 19.0 18.0 18.0 3 18.0 17.0 17.0 18.0 17.5 4 17.0 17.0 17.0 18.0 17.3 5 18.0 17.0 18.0 17.0 17.5 6 16.0 16.0 14.0 14.0 15.0 Qtr Avg 17.2 16.7 16.7 16.5 16.8 C-1 16.0 15.0 17.0 17.0 16.3 C-2 22.0 19.0 20.0 Note 1 20.3 C-3 14.0 Note 1 14.0 15.0 14.3 C-4 17.0 15.0 17.0 22.0 17.8 C-5 15.0 12.0 13.0 12.0 13.0 C-6 16.0 18.0 15.0 11.0 15.0 Qtr Avg 16.7 15.8 16.0 15.4 16.1 April 2, 2007 Page 14 of 61

Response to RAIs Dated February 27, 2007 Year 2006 Quarter Q1 Q2 Q3 Q4 Avg Location 1 25.0 25-0 19.0 21.0 22.5 2 18.0 22.0 21.0 20.0 20.3 3 19.0 19.0 18.0 19.0 18.8 4 24.0 24.0 20.0 24.0 23.0 5 19.0 21.0 18.0 17.0 18.8 6 23.0 23.0 20.0 21.0 21.8 Qtr Avg 21.3 22.3 19.3 20.3 20.8 C-1 Note 2 Note 2 Note 2 Note 2 Note 2 C-2 19.0 20.0 Note 1 21.0 20.0 C-3 17.0 16.0 14.0 15.0 15.5 C-4 18.0 21.0 22.0 19.0 20.0 C-5 Note 2 Note 2 Note 2 Note 2 Note 2 C-6 17.0 20.0 16.0 18.0 17.8 Qtr Avg 17.8 19.3 17.3 18.3 18.3 Note 1: No data available, the dosimeters were missing when collected for end of the quarter monitoring.

Note 2: Monitoring at these locations ceased after 2004 as the REMP program was reduced.

c. Please identify access roads and paths that will continue to exist after the first phase of site release and will be located nearest to the new IOSB fence line, including location and distance from the IOSB. Clarify whether access to these roads and paths are controlled in some way or available for public access. Please include travel volume estimates for these roads and paths.

Additionally, please identify the locations on a map or diagram.

Response

The figures "Structures Figure 2" and "Fence Lines" included earlier provide aerial views of the areas around the IOSB. The nearest "road" would be the area just east of the IOSB, where the controlled access fence will be placed approximately 70 feet from the eastern wall of the IOSB. The road west of the IOSB is also at its closest point approximately 70 feet away from the North-West corner of the IOSB,*but a berm separates the building from the surrounding areas on all sides but the East.

All of these roads are within the Industrial Area. Access to the Industrial Area post-License Termination has been discussed thoroughly in Section 6.4.2 of the LTP. As an update to that information, the Backup Control Center (Building "2" in.figure "Structures Figure 1" included above) is now operational and has been used to operate the District's electrical distribution system. The District will maintain a level of access control to the current Industrial Area in order to maintain the security required by the Federal Energy April 2, 2007 Page 15 of 61

Response to RAIs Dated February 27, 2007 Regulatory Commission (FERC) and other regulatory agencies governing reliability of electrical distribution systems. The public will not have free access to these areas.

d. Please indicate if there are plans to store non-radioactive waste in the IOSB.

Also, clarify whether or not there are any plans to store waste from other facilities at the IOSB and whether or not this waste is radioactive waste.

Response

There are no plans to store any waste other than Class B and Class C radioactive wastes generated at the Rancho Seco facility. Publicly elected representatives from other portions of the state of California have proposed storage of radioactive materials generated at other locations (i.e., radiologically contaminated medical waste) due to the implementation of the Low Level Waste Policy Act, and the lack of an in-compact disposal site for California waste generators. However, the District Board of Directors, and District management and staff strongly oppose storage of any materials at Rancho Seco other than the Class B and Class C radioactive wastes generated at the facility.

4. Section 8.5.1.3.1, Land Use, states that the Rancho Seco Updated Safety Analysis Report (USAR) Figure 2.2-6 provides a detailed description of all agricultural and residential activities within a 5-mile radius of the site, and USAR Figures 2.2-7, 2.2-8, and 2.2-9 identify agricultural activities within a 50-mile radius.

a. The Defueled Safety Analysis Report (DSAR), Amendment 2, Section 1.1, Introduction, states that the DSAR replaced the USAR as the primary licensing basis document applicable to Rancho Seco in the Permanently Defueled Mode. Further, Figure 2.2-4 of this document appears to be the only figure in the DSAR that identifies agricultural uses. Given these differences in descriptions between the Supplemental Environmental Report reference to the USAR and the DSAR, please provide new copies of the appropriate figures that identify current agricultural and residential activities to better assure that our review is addressing the applicable information.

Response

Attached below are Figures 2.2-7, 2.2-8, and 2.2-9 of the Rancho Seco USAR. These figures represent the agricultural activities within a 50-mile radius of the plant.

The USAR represented the licensing basis for Rancho Seco when the plant was still operating. USAR, Amendment 8 was in effect when SMUD submitted the original Decommissioning Plan and the associated Supplement to Rancho Seco Environmental Report - Post Operating License Stage. After Rancho Seco shut down permanently, the DSAR replaced the USAR as the primary licensing basis document to reflect the operation of Rancho Seco in the permanently de-fueled mode.

April 2, 2007 Page 16 of 61

Response to RAIs Dated February 27, 2007 After all of the fuel was placed in dry storage, the DSAR was further reduced to reflect that the Emergency Planning Zone (EPZ) was limited to the Industrial Area boundary.

With the reduced size of the EPZ, a detailed description of the surrounding area (e.g.,

population and land use) were no longer relevant and were removed from the DSAR.

Historical information remains available in USAR Amendment 8.

Agricultural activities within the 50-mile radius remain largely unchanged. Two notable changes are wine grapes planted to the north and west of the plant and construction of the Cosumnes Power Plant approximately 1/2 mile south of the Rancho Seco facility and within the 2,480 acre SMUD owned site.

b. Please identify references used for any information provided. Further, please include a brief written explanation of the figures provided.

Response

Figures 2.2-7, 2.2-8, and 2.2-9 are contained in USAR, Amendment 8.

Figure 2.2-7 shows fruit, nut, and field crops, Figure 2.2-8 shows pastureland and rangeland, and Figure 2.2-9 shows land used for dairy cattle.

April 2, 2007 Page 17 of 61

Response to RAIs Dated February 27, 2007 34.1.. . .

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o110 0 10 20 5-0 40 5,0 40 5,0 FIGURE 22-7 CURRENT LAND USE , FRUITS Fruits & huts AND NUTS AND FIELUD CROPS Sq mr of Fteld Clo ts SOURCEr Ainuol Agriculturol Crop Reports Colifornia State Departmenl Of SMUU Ag rnict u rot *ACRAMENTO MUNI.PAL UTIUTY DISTRCCT April 2, 2007 Page 18 of 61

Response to RAIs Dated February 27, 2007 3.9 J 5o0

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2,1 328,11 Staanis/4os 10 0 10 20 30 40 50 FIGURE 2.2.8 CURRENT LAND USE -

m 01 5Q Posture Land PASTURE LAND AND RANGE LAND m o-Roage Loifd 5~

SOURCE- Anrnual AgriculoinJal Crop Reports Ccjliformio 'State Deporiment of SMUD AgrictturO1l SACRAMENTO MUNICPAL UT7UTY DISTRICT April 2, 2007 Page 19 of 61

Response to RAIs Dated February 27, 2007

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NOTE No d.ary coUIle withh iji a 5 Ie 5 cae in miles '5 it'd ius 0

100 20 30 40 50 FIGURE 2.2M9 CURRENT LAND USE -

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Divusoini of C:ov LRt Porffubq SACRAMENTO MUNICIPAL UTILITY DISTR!CT April 2, 2007 Page 20 of 61

Response to RAIs Dated February 27, 2007

5. Section 8.5.4.1, Hydrology, states that within recent times no flooding or inundation from storms or runoff has occurred within the site boundaries.

Further, it is highly unlikely that the site could be flooded, even with abnormal rainfall intensities.

a. Please identify what period of years the wording "in recent times" is intended to include.

Response

The term "within recent historical times" has been used in Rancho Seco licensing basis documents without definition beginning with the Preliminary Safety Analysis Report (PSAR) submittal and currently exists in the DSAR. As indicated in the response to RAI 5.c below, the Rancho Seco site is outside the 100-year floor plain. Therefore, term "within recent historical times" can be defined as a period of time greater than 100 years.

b. Please provide the specific reference(s) for the source(s) of both the "recent times" determination and conclusion that it is highly unlikely that the site could be flooded.

Response

Please refer to the response to RAI 5.c below.

c. Please identify the location of the nearest flooding outside of the current site boundaries for the same period of years or at least the last 100 years, whichever is the longest period of time.

Response

The answer to this RAI was provided in response to RAI No. 40 contained in the first set of RAIs. 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. Figure 2-3 from the Hydrogeological Characterization Report is provided on the next page followed by a portion of the map located at the referenced url, which shows the 100-year flood plain near the Rancho Seco site location without contour lines. As shown on the two maps, the nearest 100-year flood plain outside of the current site boundaries results from Hadseville Creek north of Twin Cities Road (Hwy 104) across from the main entrance to the site.

April 2, 2007 Page 21 of 61

Response to RAIs Dated February 27, 2007 Apd12,2007 Page 22 of 61

Response to RAls Dated February 27, 2007 I/

RSNGS Site 1L IN 100 Year Flood Area Based on Federal Insurance Rate Map, Index dated July 6, 1998. Total Floodplain area 149,458 ac

.E HA 0 A99

• AE E AO The above ZONES Indicate areas within the Special Flood Hazard Area (Flood Insurance may be required!)

.11] [L1 X (NotIn Special Flood HazardAea)

April 2, 2007 Page 23 of 61

Response to RAIs Dated February 27, 2007

6. Throughout the plan and, especially, in Chapter 2, Site Characterization, the terms Industrial Area, Area 8, Impacted Area, and Un-Impacted area are used (example: Sections 2.1.7.3, 2.1.10, and Section 2 figures).

a. Please clarify the size of each area (e.g., acres), other than the Industrial Area (already indicated in the LTP).

Response

LTP Figure 2-1 shows the Industrial Area of the Rancho Seco site. As stated in LTP Section 1.3.2 "Site Description," the Industrial Area is 87 acres. LTP Section 2.1.8.4 "Area 8" defines Area 8 as being the Industrial Area. Therefore, the size of Area 8 is also 87 acres.

LTP Figure 2-2 shows the Impacted Area. The size of the Impacted Area is approximately 165 acres. Accordingly, the size of the Un-Impacted Area is approximately 2,315 acres.

b. Please clarify the location of barriers and access points (e.g., fences and gates) that are currently associated with these areas and will remain after these areas are released from licensing. Further, identify the type and location of any new barriers or access points that will be established with release of these areas.

Response

LTP Figure 2-1 shows the Industrial Area including the Industrial Area fence line.

Access to the Industrial Area is through the gate at the Personnel Access Portal (PAP) building. The Industrial Area fence will remain in place after decommissioning is completed.

There is also a fence, with a personnel gate and a vehicle gate, surrounding the ISFSI.

This fence will remain in place as long as the ISFSI is operational. Access to the ISFSI also requires access to the Industrial Area.

Before the completion of the first phase of decommissioning, SMUD will construct a fence, with gates for personnel and vehicle access, around the IOSB. Upon completion of the first phase of decommissioning, the fence surrounding the IOSB will define the 10 CFR Part 50 licensed site until the completion of the second (last) phase of decommissioning and termination of the 10 CFR Part 50 license.

c. Please clarify the location and approximate size (e.g., acres) of all recreational areas in the vicinity of Rancho Seco and the approximate distance from the Industrial Area. Include a listing of recreational activities, for areas not already described. Please clarify the location of any water recreation areas and their position along the hydrogradient (e.g., up-gradient, April 2, 2007 Page 24 of 61

down-gradient) from the Industrial Area. A size estimate for Rancho Seco Lake is already provided, but clarifications are needed regarding what recreational activities take place at the lake.

Response

The land surrounding the Rancho Seco site is almost exclusively agricultural. The hydrogradient of the site runs from northeast to southwest.

The Castle Oaks golf course, located in the city of lone, is approximately 10 miles east of the site. The Dry Creek golf course, located in Gait, CA is approximately 10 miles southwest of Rancho Seco and is down-gradient from the site. The Rancho Murieta golf course is located approximately 10 miles north of the site.

A portion of Lake Camanche reservoir is approximately 10 miles southeast of the Rancho Seco site. Lake Camanche covers 12 square miles, is 150 feet deep, and has 53 miles of shoreline when full. Both the North and South shore provide a variety of recreational activities and services including tent and RV camping, cottage rentals, boat rentals, boat launch, and fishing.

Lake Amador is approximately 13 miles east of Rancho Seco. The lake is approximately 400 acres with approximately 13 1/2 miles of shoreline. Recreational activities include tent and RV camping, boating, picnicking, and fishing.

Recreational activities at Rancho Seco Park include picnicking, tent and RV camping, boating, fishing, and swimming. The park also has a 75-acre wildlife compound, located just southwest of the lake's dam, and a seven-mile nature trail that starts at the north end of the lake.

The nature trail is the product of a partnership between SMUD and The Nature Conservancy. In 1999, The Nature Conservancy purchased 12,000 acres of the Howard Ranch, which is located adjacent to Rancho Seco Lake. The conservancy placed permanent protective restrictions on the property and resold the land to a local cattleman, The Howard Ranch remains a working private cattle ranch.

The conservancy hired the California Conservation Corps to construct the trail, which was opened to the public in June 2006. SMUD provides road access to the nature trail as well as public parking at the trailhead. SMUD also provides ongoing maintenance on the trail.

7. Sections 8.7.1, Federal Requirements, and 8.7.2, State and Local Requirements, identify regulations, permits, licenses, notifications, and approvals that are in place during decommissioning.

a. From these Sections, please provide a listing of local, State, and Federal regulations that will continue during the period when only the IOSB remains April 2, 2007 Page 25 of 61

on the NRC license, as well as, afterward, when the entire site is released from the license.

Response

During the period when only the IOSB remains on the NRC 10 CFR Part 50 license and the ISOB remains under the 10 CFR Part 72 license, all of the Federal, State and local requirements listed in Sections 8.7.1 and 8.7.2 will continue to apply. When the entire site is released from both licenses, the NRC requirements listed in Section 8.7.1.1 will no longer apply; however, the Cal/OSHA and EPA requirements listed in Sections 8.7.1.2 and 8.7.1.3 and the State and local requirements listed in Section 8.7.2 will continue to apply because the site will be maintained as an industrial site.

b. The Federal Requirements listing indicates that Rancho Seco must comply with the U.S. Environmental Protection Agency regulations for underground storage tanks (Part 280 of 40 CFR). Please clarify whether any tanks will remain on the site after the site is released from NRC licensing. If so, please identify their past and, if applicable, continued use, as well as any performance issues.

Response

There currently are no underground storage tanks on the Rancho Seco site and none are planned to be added after the site is released from NRC licensing.

8. Section 8.5.1.3.3, Water Supply, identifies that potable water comes from four wells and one well serves a residence located at the northeastern corner of the site.

a. Please summarize plans for operation of the plant's water supply system with release of the site from NRC licensing.

Response

The plant's water supply system will remain in operation after the release of the site from NRC licensing.

b. Please specify the approximate distance between the current Industrial Area fence and the residence located on the site.

Response

The distance between the Industrial Area fence and the residence located on the Rancho Seco site is approximately 1 mile.

April 2, 2007 Page 26 of 61

IN SITU GAMMA SPECTROSCOPY ISSUES GeneralDiscussion of In Situ Gamma Spectroscopyat Rancho Seco There appears to be confusion over the use of in situ gamma spectroscopy at Rancho Seco for final status survey (FSS). The system used is the Canberra ISOCS system consisting of either HPGe or Nal detectors that have been characterized by the manufacturer such that they can be accurately employed with any source geometry that can be adequately described by the "geometry composer". Not only does this mean that National Institute of Standards and Technology (NIST) traceable sources are not required for every geometry used but it also means that a given spectrum can be analyzed using multiple geometries with a high level of accuracy. It is this capability that allows the spectrum collected from a large area to be analyzed as a small hot spot at the edge of the field of view by directly comparing source activities rather than efficiencies or some other parameter. This makes it simple to determine the ratio of the small area source response to that of the large area source response. By establishing the investigation level at the level of the elevated measurement comparison (EMC) divided by the ratio of the two responses, an analytical result less than the investigation criterion means that a small hot spot with an activity greater than the EMC value could not be present within the field of view. This approach does assume the activity in the hot spot and the large field of view is homogeneous, as does MARSSIM.

As stated in the referenced ORISE comments (ADAMS ML06360021) on in situ gamma spectroscopy, MARSSIM does not consider discrete radioactive particles (DRPs).

There have been almost as many ways of dealing with DRPs as there have been Decommissioning or License Termination Plans. Many LTPs made no mention of particles at all (e.g., Trojan, Big Rock Point, and Hadem Neck ). The Shelwell site, which underwent decommissioning outside of Columbus, Ohio in 1998, determined the probability of finding a particle in a given 1 M 2 ; determined the potential number of particles per year that could be ingested or inhaled; and the resultant "expectation dose". Maine Yankee and Yankee Rowe determined the sensitivity of their method of walkover scan with respect to DRPs to be 1 uCi of Co-60. Meanwhile, the NRC has not published the DRP sensitivity of the walkover scan described in NUREG-1 575 nor have they determined an activity of DRP that is dose significant from the standpoint of 10 CFR Part 20.1402.

The decommissioning rule requires licensees to determine the potential annual dose to the average member of the critical group. Of the few reference documents available that discuss the dosimetry of DRPs, only NCRP-1 30, "Biological Effects and Exposure Limits for Hot Particles", discusses the dose to the lung or GI tract from the inhalation or ingestion of a DRP. NCRP-1 30 does not provide a dose per unit activity for either inhalation or ingestion, it rather references the use of dose factors (such as those found in Federal Guidance Report FGR-1 1) for the insoluble form of the particular radionuclide. The report does stress that inhalation or ingestion is an extremely unlikely event based on industry experience and the physical characteristics of DRPs. This is further supported by an NRC "Regulatory Analysis of Revisions to 10CFR20 Unified Skin Dose Limit October 2001" which stated that a survey of nuclear plant experience April 2, 2007 Page 27 of 61

with DRPs showed that, of the 15,068 DRPs reported, only 0.2% involved both a skin contamination and an activity of >1 uCi. Given the unlikely nature of an inhalation or ingestion event and the very limited number of workers potentially exposed under the industrial worker scenario, it seems unlikely that DRP internal exposure is a credible scenario for the average member of the industrial worker group.

Because of the difficulties presented by DRPs, the emphasis for decommissioning is placed on prevention and control measures. Each operating power plant developed a "hot particle" control program that covered detection, prevention, control, and dosimetry for DRPs. At Rancho Seco, that program is still being administered by the Radiation Protection Group for decommissioning activities. Controls are established for remediation of survey areas as necessary based on characterization data. During structure remediation, both beta and gamma sensitive instruments are used to evaluate the effectiveness of structure decontamination. Once it appears that residual activity is less than the derived concentration guideline level (DCGL), areas are vacuumed, wiped down, or otherwise cleaned prior to FSS. Before the final survey can begin, access controls are established at the entrance to the survey area to prevent recontamination.

These measures make it highly unlikely that a DRP will be present in the survey area.

The likelihood of finding DRPs is greatest within Class 1 structures and least within Class 3 soils. This means that the decontamination, detection, and control measures are being applied to the proper areas. It also means that the lower in situ gamma spectroscopy MDAs will be achieved in the areas where greater detection sensitivity is desirable. Rancho Seco decommissioning technical basis document DTBD 06-003, "Use of In Situ Gamma Spectroscopy for FSS," recommends the use of supplemental Nal detector scans for soils with a high potential for DRPs (i.e., Class 1 soil). These practices taken in total minimize the potential for significant undetected DRPs in FSS areas.

Hot Particles 9.1 During a recent visit to the site, the NRC staff observed "Hot Particle" control areas. Please provide a historical assessment of hot particles at Rancho Seco.

Please describe how your hot particle survey program relates to the remediation and final status survey programs. Please provide a technical bases for the hot particle detection program.

Response

While Rancho Seco has detected hot particles on site during its history, the numbers and activities associated with the particles have not been as great as some other facilities. The number of particles detected per year since decommissioning 1 The numbering of the "In Situ Gamma Spectroscopy Issues" RAIs has been revised to continue the numbering sequence used for the "Environmental Issues" RAIs.

April 2, 2007 Page 28 of 61

began in 1990 is approximately 14 with an average activity of 0.013 pCi and a maximum of 0.36 puCi.

Rancho Seco relies on Site Characterization to properly identify Class 1 areas, including whether particles are present, and the Hot Particle Program to identify and control any particles actually found. When these areas are ready for remediation, radiological controls are established based on characterization data. These controls limit access into and out of the areas; detect and control contamination sources, including DRPs if necessary; and monitor remediation progress with repetitive surveys until the area is ready for final survey. By the time the area is turned over for FSS it has undergone multiple courses of decontamination and survey with many different types of survey instruments to ensure it will meet the release criteria, including the EMC.

The hot particle controls observed by the NRC were put in place as a precaution given the types of activities being performed at the time (e.g., vessel segmentation in the reactor building, pipe decontamination in the Aux Building), not because large numbers of particles have been recently detected. The presence of particles. in Class 2 and 3 areas is extremely unlikely as evidenced by the very low activity levels reported in those FSS surveys. Particles are more likely to be found in Class 1 structures and on the soil adjacent to them. These are the areas requiring more remediation and more surveys with more than one type of instrument which increases the likelihood of detection if particles are present.

The Hot Particle Program is covered in the attached procedure RP.305.09E, "Hot Particle Controls". The Program described in procedure RP.305.09E is consistent with similar programs used throughout the nuclear utility industry. The Program has been in place for several years and has been successful in detecting and controlling particles as part of the site Radiation Protection Program.

The technical basis for the Hot Particle Control Program used at Rancho Seco is the same as that used throughout the nuclear industry. It.is based on the referenced industry guidelines (viz., NRC IN 87-39, NRC IE Notice 86-23, and NRC IN 90-48) and is used to detect, control and remove particles from FSS areas during the remediation process. Its implementation ensures that when final surveys are performed there should be no DRPs in the survey area just as there should be no significant areas above the DCGL.

10. In DTBD-06-003, Rancho Seco identifies the method for determining the Investigation Criteria. DTBD-06-003 states:

"Determinationof the Investigation Criteriais based on taking a series of measurements using the detector in a standardgeometry, such as a disk, located at a defined distance from the detector. The requiredgeometry parametersare entered into the geometry composer and the acquiredspectra area analyzed using the standardgeometry. A new geometry is then developed April 2, 2007 Page 29 of 61

which reduces the source to an area of I m 2 located at the periphery of the detector field of view. The originalspectra are then re-analyzed using the new, small source area geometry. The ratio of the full field of view activity to the small2 source activity is determined and the ratio is multiplied by the DCGLemc for a I m area which becomes the Investigation Criterion."

How does Rancho Seco determine if the activity measured is uniform activity, a hot particle, or2 a smaller area that exceeds the DCGLemc averaged over an area less than 1 Mi ?

Response

The detailed investigation survey, performed following detection of an elevated area, is the mechanism used to determine the size of the source causing the elevated reading.

In situ gamma spectroscopy is typically used to perform scan surveys of land and structures. The purpose of the scan survey is to identify areas for further investigation based on detecting an elevated measurement result. It doesn't matter whether the elevated measurement is caused by a large area of uniform activity, a small area with high activity or a discrete particle. As long as the measurement exceeds the investigation criterion, the scan area will require further investigation to determine the actual location, size, homogeneity, and level of activity responsible for the elevated measurement.

11. DTBD-06-003 states, "It is anticipatedthat final surveys will typically be performed with the detector at a distance of 2 m to 3 m from the source with a 90 degree collimator 2 installed. This geometry defines a detector field of view (FOV) of 12 m 2 to 28 mi .'

What is the minimal detectable activity (MDA) using a 12 m 2 FOV vs using a 28 m 2 FOV, assuming a hot particle is present in the FOV on soil and structure surfaces, at a depth of 2 cm in concrete and at a depth of 15 cm in soil?

Response

Count times are established to achieve the required MDAs so there is no difference in MDAs between either a 12 m 2 FOV or a 28 m2 FOV. MDAs for soil are typically < 0.5 pCi/g and for structure surfaces are typically < 1,500 dpm/1 00 cm 2 . Scan measurements are made using the "count to MDA" function which ensures that the MDA achieved will meet the investigation criterion, however count times are usually in the 600 to 1,000 second range. The table below shows the typical minimum particle activities detectable for the geometries indicated based on actual MDAs for the given FOV. The 2 cm depth for concrete structures refers to the possibility of contamination slightly below the surface rather than a discrete particle embedded in concrete.

April 2, 2007 Page 30 of 61

MDAs For Particles With Various Geometries ISOCS Geometry & FOV Particle Located In Particle Located At Edge*

.Center Soil Surface, 28 m2 < 0.4 uCi Co-60 < 1.1 uCi Co-60 Soil at 15 cm, 28 m2 1.7 uCi Co-60 4.3 uCi Co-60 Concrete Surface, 3 m n2 0.9 uCi Co-60 2.5 uCi Co-60 Containment Liner, 28 m2 1.4 uCi Co-60 3.6 uCi Co-60 The MDAs for Co-60 particles are presented because they are the most common particle.

• The MDAs do not reflect the lower activities resulting from the overlapping fields of view for Class 1 areas.

12. If such a hot particle exists, how does ISOCS determine its position in the FOV?

Response

As explained in RAI #10 above, the in situ scan measurement is not used to locate the position of the elevated activity but rather is used to identify a scan grid for further evaluation. The identified grid is investigated using a separate written survey plan that may include the use of gas proportional detectors, Nal detectors, volumetric samples, or additional in situ measurements with reduced fields of view. It is the investigation measurements that identify the location, source and activity of the elevated reading.

13. Based on the MDAs for hot particles, what is the dose implication if such a hot particle is present?

Response

For particles buried in soil, the direct dose from a 4 uCi particle of Co-60 for 2,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of exposure (based on the industrial worker scenario) at 100 cm is 1.2 mRem/y. The detection methodology is more sensitive for particles on the soil surface and a I uCi Co-60 particle for 2,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of exposure at 100 cm would be 2.6 mRem/y. These particles are easily detectable in the presence of underlying soil with little or no significant activity above background (i.e., Class 2 and 3 survey units) and the total dose would be less than 10 CFR Part 20, Subpart E limits.

Combining 2"x2" Nal scan surveys with in situ scans for Class 1 soil surveys ensures that discrete particles of significant activity (i.e., greater than 1 uCi on the surface) would be detected in order to meet 10 CFR Part 20, Subpart E limits.

April 2, 2007 Page 31 of 61

Discrete particle contaminations of personnel typically occur indoors. The indoor areas are more likely to have discrete particles present prior to remediation and close proximity to the particle is usually needed for a worker to become contaminated. The performance of multiple surveys of structures during remediation and FSS make such contamination events unlikely.

In Situ Gamma Systems at Rancho Seco 14.2 Please provide the technical bases that assures that the DCGL and elevated concentrations do not exceed the depth of 15 cm of soil or 2 cm of surface on structures? Please provide your bases for MDAs taking into consideration the spatial and volumetric measurements you plan to make.

Response

The soil remediation techniques used and the post-remediation surveys conducted ensure that FSS scans are only performed on a soil source depth of 15 cm. The in situ geometry used for soil measurements is defined for a depth of 15 cm and the geometry used for structures is defined for a depth of 2 cm or more. Volumetric samples are taken at the prescribed depths to accurately determine the "as left" activity. Attached is the revised DTBD 06-003, "Use of In Situ Gamma Spectroscopy for Final Site Survey",

which presents the MDAs and investigation criteria for homogeneous sources. The "count to MDA" feature ensures that the MDA achieved is appropriate for the investigation criterion of a given measurement, including consideration of DRPs, if necessary. DTBD 06-003, Rev. 0 was previously submitted to the NRC with all attachments. The attachments were not changed in Rev.1; therefore, the Rev. 1 without attachments is provided in Attachment 2.

15, Soil moisture can adversely impact the quality of ISOCS measurements. How does Rancho Seco identify and adjust for soil moisture while using ISOCS?

Response

DTBD 06-003 describes the use of massimetric efficiency to reduce the impact of media density or moisture effects. Soil scans are not performed during the rainy season because of the difficulty of getting equipment into the field when the ground is very soft.

During the dry season, the ground has little residual moisture. With MDAs of 1 pCi/g or less and DCGLs of 50 pCi/g, there is little effect on the scan evaluation even if soil moisture induced an error of 10 to 15 percent. Furthermore, for soil surveys, the direct measurements are typically volumetric soil samples that are dried and counted in the laboratory which eliminates the moisture effect altogether.

2 The numbering of the "In Situ Gamma Systems at Rancho Seco" RAIs has been revised to continue the numbering sequence from the "Hot Particles" RAIs.

April 2, 2007 Page 32 of 61

16. Describe how the proposed ISOCS measurements with the proposed FOV will meet the DQOs for the FSS.

Response

The MDAs for in situ gamma spectroscopy are a very small fraction of the DCGLs for either soil or concrete (less than 3.5%) and the use of conservative investigation criteria ensure that elevated measurements are identified and investigated in order to demonstrate compliance with the Elevated Measurements Criteria. This ensures that the DQOs will be met.

17. How does Rancho Seco use the naturally occurring radionuclides that will be identified in the ISOCS measurements to assure quality operations or to identify equipment malfuntion?

Response

When the FSS Engineers review the in situ gamma spectroscopy results, they note the presence of naturally-occurring radionuclides and whether the activity levels are consistent with known site levels. They also note whether the reported photo peaks are at the proper energy location within the spectrum and if the full width half maximum (FWHM) values meet the analytical specification. These evaluations, coupled with the daily pre- and post-QC source counts, ensure proper operation of the detectors.

OTHER 18.3 In Section 6.4.2, pg. 6-6. Rancho Seco identifies an "industrial worker scenario for surface and subsurface soil exposures" for unrestricted release. It further states in Section 6.4.2.1 that "...the public does not have ready access to the remaining areas of the site". More specifically, please provide assurances as to how RS will maintain these areas under the industrial worker scenario after the first phase and after the second phase (See Section 8.3 Site Description After Unrestricted Release, pg. 8-4). What mechanism will RS use to maintain these areas as an industrial worker scenario?

Response

No controls are required to be implemented after license termination because Rancho Seco is being decommissioned under 10 CFR Part 20.1402 for unrestricted release, not under 10 CFR Part 20.1403 for license termination under restricted conditions.

3 The numbering of the "Other" RAIs has been revised to continue the numbering sequence from the "In Situ Gamma Systems at Rancho Seco" RAIs.

April 2, 2007 Page 33 of 61

Justification for selection of an industrial worker scenario for surface and subsurface soil exposures to use while performing dose modeling was provided in Section 6.4.2 of the LTP. Section 6.4.2 concluded that it is reasonable to assume that the District will retain ownership of the site for the foreseeable future and that members of the public will not have ready access to Impacted Areas of the site. Section 6.8 of the LTP compared alternative exposure scenarios for Impacted Area soils. Section 6.8.2 evaluated the most conservative exposure scenario, the resident farmer scenario. Section 6.8.2 concluded that, after a period of approximately 30 years, Rancho Seco would comply with the requirements of 10 CFR Part 20.1402 even under a resident farmer scenario.

Therefore, the foreseeable future only needs to consider a period of 30 years following the first phase of license termination.

The entire 2,480 acres of SMUD owned property is surrounded by some type of fencing, usually cattle fencing. The response to RAI No. 1.b. discusses the fate of the existing Industrial Area during the foreseeable future. The fence enclosing the Industrial Area will not be removed during decommissioning. Upon completion of the first phase of license termination the Industrial Area will be maintained as an industrial site with access controlled by the SMUD Asset Protection Department (industrial security). The IOSB, which will remain under the 10 CFR Part 50 license until completion of the second phase of license termination, will be contained within this industrial site. The Backup Control Center in the Administration Building, the Training and Records Building with occupied offices and the active switchyard will also be contained within this industrial site. Upon completion of the second phase of license termination, access to the industrial site will continue to be controlled by the SMUD Asset Protection Department. This can reasonably be assumed to include at least a period of 30 years following completion of the first phase of license termination.

4 SUPPLEMENTAL INFORMATION The site reservoir (i.e., Rancho Seco Lake) was designed to supply emergency plant cooling water in the event that water from Folsom South Canal was not available. The lake is located approximately 2 miles southeast of the Industrial Area boundary.

The dam is under the jurisdiction of the State of California, Division of Dam Safety.

Accordingly, it is designed and constructed to standards established by the State of California, which include consideration for earthquakes.

The probability of a sudden failure of an earth structure is very small. However, as part of the original plant licensing, the effects on the plant of a dam failure or other sudden release of water were evaluated. The analysis showed that an instantaneous break 50 feet wide, the full height of the dam, occurring simultaneously with the peak flow from the design storm will not flood the plant site. The resulting flow would have had a water surface that would have been more than 10 feet below any of the plant safety features.

4 Information requested during a March 19, 2007 conference call between NRC and Rancho Seco personnel.

April 2, 2007 Page 34 of 61

Attachment 1 Hot Particle Controls Procedure RP.305.09E

Response to RAIs Dated February 27, 2007 MANUAL: RADIATION CONTROL MANUAL NUMBER: RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 1 OF 16 LEAD DEPARTMENT: EFFECTIVE DATE:

REVISION SUM61MARY:

1. Removed references to RP Responder.. RP Responder Program has been deleted.

2'. Added clarification to,"Prerequisites" section-

3. Added clarificalion to section 6.6.1 for RWP -equ~rements

4. Revised sec~nor on Hot Particle Control Exemptions. Deleted section on %Oýerations activities., inspeciorns, and' I&C furnctios".

5. Revised secfion on Hot Partide survey requirernents for dariffcation..

April 2, 2007 Page 36 of 61

MANUAL: RADIATION CONTROL MANUAL NUMBER: RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 2 OF 16 PURPOSE 1.1. To proaide the Radiation Protection requirements for Hot Particle control, assessment and responsee (COMMITMENT: Ref. 2-2.1).

2. REFERENCESI COMMITMENT rDOCUMENTS 2.1. Referen ces 2-.1. Title 10, Code of Federal Regulations, Part 20, Standards For Protection Against Radiation 2.1.2- U.S. Nuclear Regulatory Informaton Notice, Numbfr 87-39, Control of Hot Partcte Contamntination at Nuclear Power Plants-2.1-3. U.S. Nuclear Regulatory IE Information Notice.., Number 86-23, Excessive Skin Exposures Due To Contamination With Hot Particles.

2-1.4. U.S. Nuclear Regulatory Informaton Nbtice, Number 90-48,,

Enforcement Policy For Hot ParTicle- Exposures.

21.5. RP.305.D4,, Radiation Work Permits 2.1.6. RP.&U&.07, Area D,,finitions, Positng, and Requirements 21.7. RP.305.08A, Routine and Radiation Work Permit Surveys 2.1.8. RP.3D5..9A, Removal] of Tools and Equipment From Controlled Areas 2.1.9. R-P.305.,19B, Personne~l Contamination Monitoringi 2-1-10. RP.3116.09C, Decontamination Procedures 2.1.11. RP.305.09D, Personnel and Clothing Decontamination and Reports 2.2. Commitment Documents 2.2.1. LER 88-003, Personnel O,,rerexposure Due to a Hot Particle April 2, 2007 Page 37 of 61

MANUAL: RADIATION CONTROL MANUAL NUMBER: RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 31 OF 16

3. DEFIN'UTIONS 3.A. HOT PARTICLES - Highly radioactve (ac,,ty greater than 25,000 ccpn at 0.5 inches with an RM-14 equipped withi an: HP-260 probe or equivalent),

discrete., small particles of either irradiated' Fuel Fragments or neutron acvatedl corrosion and wear products.

3.2. ZONE I - An area verified' to be free of Hoa Particles and unlikely to become contaminated with Hot FPfrtcles-3.3. ZONE 2 - HOT PARTICLE BUFFER ZONE - An area verified to, be free of Hot Particles but havin.1 the potentia] of beconi~ng contaminated withi Hot Particles.

3.4. ZONE 3 - HOT PARTICLE ZONE iHPZ) - An. area krov;wn or suspected to contain Hot Particles.

4. PREREQUISITES 4.1. All persons entering Hot Particle Zones. shall be familiar wvith the Hot Particle ControLs in effect in the area they are working in- Specitic info:rmatbn on Hot Particle controus for vwork areas is listed on the. appilicable RWP for the area.

General information on Hot. Paricle controls is available from RP Supervision and RP Technicians assigned coverage En the %ork areas.

5. PRECAUTI:ONS 5.1. Hot Partides, iidentified on personnel, must be tocated and renioved in: an expeditious manner.

5.2. The RWP contains specific requirements for Hot Partite control,.

April 2, 2007 Page 38 of 61

MANUAL: RADIATION CONTROL NANUIAL NUMBER- RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 4 OF 16

6. PROCEDURE.

INDEX 6.1 Establishrtn Hot Partice Zones 6.2 Posting Requiremrents For Hot Particle Zones 6.3 Hot Partitle SuTiwy Methods 6.4 Hot Particle Identifircation Techniques 6.5 Hot, Particle Survey Requirements 6.6 Hot Particle WoV Requiremients 6.7 Response to Hot Particle Detection O:utside* HPZs 6.8 Response to Hot Particles on PersonneO Outside HPZs 6.9 Response to Hot Particle 'Detection in an HPZ 6.10 Response to Hot, Particles on Personnel in an HPZ 6.11 Protective Clothing 6.12 Removal of Contaminateci Equipment from an HPZ 6.13 Persortnel Egress from Hot Particle Zones 6.14 Hot Particle, Trash 6.15 Deposting Hot Particle Zones 6.1. Establishinq Hot Particle Zones 6-1.1. IRP SuperAsion is responsible for establishing Hot Particle Zones (HPZ) and implemanting Hot Particle controls.

61-.2. Establish HPZs for work in areas that meet either of th*e fo*wllting criteria:

6.1.2.1. The area: or component is known toý be contaminated With Hot Particles.

6.1.2.2. Work is perfomied in an area or on a component/system that is suspected to contain Hot Particles based on previous filndings of Hot Particles, or plant conditions.

April 2, 2007 Page 39 of 61

MANUAL: RADIATION CONTROL MANUAL NUMBER: RP-305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 5 OF 16 6.1.3. Review each job .rndidualy,tG determirnee the need for Hot Partcle controls. Typical areas where Hot Particde controls may be implemer*nte} include systems or components that have come into direct contact with prinmary coolant, spent luet cooiant., or ftue harndling eqipment.

6.1A.4 Areas with contaminaton levels greater than or equal! to 151,,6]00 dpnil(1 cm2 are normally controlled as HPZs because it is difficult to verify the absence of Hbt Partides.

6.A.5. At the discretion of RP Supervision, the follo,*1n activites andý equipment are norn-mlly exempt from Hot Particle controls:

6.1.5.1. RP and Chemistry sampling: evolutions, samples, and suirveys that do not require %,hlolebody entry into a posted HPZ.

6.1.5.2. C.osed, component internals such as Tygon tubing (or equivalent), used to direct leakage to drains, unless workiing on the component 6.2. Posting Requirements For Hot Particle Zones NOTE Hot Particle controls do not take the place of, NOR have more importance than normal contaminaiton conirol requirements.

6.2.1. Post the HPZ and the Hot Particle Buffer Zone (Zone 2) En accordance jith RP_305.07.

6.2.2- A phtysical barnter (i.e., herculite pen, railing, or wafl) around an HPZ, eliminates the. requrement to establish a Hot Parfcle Buffer Zone.

6.2.3. Zone 1 areas are not required to beL specifically identified or postedl April 2, 2007 Page 40 of 61

MANUAL: RADIATION CONTROL MANUAL NUMBER: RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 6 OF 16, 6.3. H-ot Particle Survey Methods NOTE KIis prudent to use tape to remove hot particte contani~nation from vwrkers as surveys are performed..

6.3-1. Orect Survey 6.3.1.1. A direct survey refers to measuring clntaminatwn where ft exists using a surey instrun-ent ar frisker-6.3.1.2. A direct survey is preferred in the fo~lowing instances:

6.3.1.2.1. On personnell wh'n background tevells are not restric@re 6.3.1.2.2. On irreg-ular surfa*es and for detecting 'fix~e Hot Partidles ,(i.e., cracks and crevices) 6-3.1.2.3. When precise location of "parcle is desired 6.3.1.3. A direct survey should be performed in a slow, deliberate manner: tal.ing time to, cover all areas-6.3.1.4. Perform direct surneys of p5ronel working, in an HPZ. if possible. Survey the whole body, concentrating on areas of the body that are suspect to.high* contamin,ation tevels, ike.,

hands, knees: feet:, etc., at the frequency specified in 6.5.5.

6.3.1.5. Identiied Hot Particles should be captured using tape, masslinn. or si:ntilar method.

6.3.2. Indirect Survey 6.3.2.1. An indirect *urve* refers to measuring removed contanminatbn us*inr, a wipe technique (massibnn,. tape: etc.).

April 2, 2007 Page 41 of 61

MANUAL: RADIATION CONTROL MANUAL NUMBER: RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 7 OF 16, 6.3.2.2. An irndirect swuvey is preferred in the follmving instances:

6.3.2'.2.1. When covering large surface areas 6.3.2.2.2. To effectively pick up Hot Particles 6.3.2'.2.3. In high background areas to minimize time spent in the area.

6.4. Iot Partide Identification Technigues 6.4.1. The described techniques apply to Hot Partides that have been secured in nmaseftinn, tape, etc.

6.4.2. Lay the mas-slinn or tape out flat in a low background area and slbwvJy frisk at a distance of 112 i.nch using an RM-141 HP-2119, or equiament,,

on fast response. IF the contamination ,evels are greater than 50,GDD ccprn, THEN a Ludlum-1TT, at 112 inch., OR an open ,w'ndow RS-2, at a distance of I inch (from the source to the detector vwndow)ý, may be used,.

6.4.3. IF areas, of significantly higher ac#vitb are found, THEN cut the rnasslinn (or tape) into smaller pieces in order to, isolate the partice.

Refer to RP.305.09D for dose estimate nmethods.

6.4.3.1. Use a RP Badge, or material of equivalent demsity thickness, as a shield between the Hot Particle and the frisker probe or the open window RGL2.

6.4.3.2. IF the count/ dose rate decreases dramatically when shielded, i.e., by 0t,%, THEN suspect a Co-60 crud particle.

6.4.3.3. IF the count dose rate does not, decrease dramnatically when shield5d, i.e., less thran 5M, THEN suspect a Fuel Fragmet.

6.4.4. Place the piece of material contai'ning the Hot Particle in a container and seal the edges with tape. [ncI*ude date, time, and the appropriate survey number or contamination report number.

6.4.5. Unless otherwise specified by RP Supervision, send the particle(s) for isotopi~c analysis.

April 2, 2007 Page 42 of 61

MANUAL: RADIATI ON CONTROL MANUAL NUMBER: RPR305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 8 OF 16 6.5. Hot Partidle Survey Retuirements 6.5 HPZs are not required to be surveyed for Hot. Particles when no work is being performed in that HPZ.

6-5.2. When no work is in progress in an HPZ,. survey areas for Hot Particles at the follo,\ng f-equenci as a minminum:

6.5.2.1. Zone 1 areas and walktways at least weekly 6.5.2.2. Zone 2 (established buffer zone), prior to HPZ entry 6-5.3.. When Hot Particle work is in progress, survey all directly adjacent Zone 1 andi Zone 2 areas once per shfft. Include step off peds in this survey.

6.5.4- For vrk in an HPZ, perfom],Hot Particle surveys upon initiaD entry and during work evolutions that may increase the potential' for spreading Hot Particles.

6.5.5. Guidelines for performing peomnneJl Hot Particle Surveyss ,[sed on the detected Hot Particle activity found using an RO-2 (open %indow

- closedvwndow, at i inch)] are:

6.5.5.1. Every 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />s: <5 mR/hr 6.5.5.2. EveTy 2 houTs: 5 to t5 mR/hr 6.5.5.3. Once per hour (not to exceed 60 mi.): 16 to 30 mRJhr 6,5.5.4. Contact RP Supervision and evaluate decontaminatng area.: >30 mR/hr Note For areas, wotich have detected* hot particle actity greater la 130 mR'hr,., decontamninating, the area should be constdered.

6.5.6- In areas where general area dose rates are very h5gh, i.e., hundreds of nPRAr or greater, Hot Particles may be difficult to. detect- In these instances, survey for Hot Particles per the guidance of RP Supervision-6.5.7. Document the performance of all Hot Particles surveys per RP.30.:08.A and include the follmAng information:

April 2, 2007 Page 43 of 61

A.NIUAL: RADIATION CONTROL MANUAL NUMBER: RRP305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 9 OF 16 6.5.7.1. Whether or not Hot Particfes were found 6.5.7.2. GCPM or open vdindow minus closed window reading for Hotl Particles detected 6.5.7.3. Frequency that personnel were surveyedl for Hot Particles, if applicable 6.6. Hot Particie Work Requrenments 6-6-1. RWP Requirements:

6.6.1.1. A Radiation Work Permit (RWP), which allows work in a HPZ, is requred for ag work perfomied in an HPZ in accordance %%ithRP.305.04.

6-6 Continuous Radiation Protection coerage is required for aEl entries into HPZs.

66.3. Ma r the RWP withi the words HOT PARTICLE CONTROLS in the special instrucions block of the RIP. Special instructions wiBl be tused to clarify Hot Particle Controls.

6-6 The normal frequency for surveying ,the personnel working in the HPZ slhould not exceed: 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. Specify the frequency in, the special instructions block of the RWP.

6.6-5. Before starting work, a job briefing is required for RWPs that cover work in HPZs.

6.6.5.1. The Hot Particte Job 8i:,efing should address., as a minimum, the foiowing:

6.6.5.1.1. RWP requiraeents, and any speciall instructions 6.6.5.1.2'. Purpose of the periodic personnel surveys and the expected job evolutions that may require special surveys.

6.6.5.1.3. Response to di-covering or suspecting personnel Hot Particle contandination 6.6.5.1.4. The proper undressing practices and sequence to prevent personnel contanination.

April 2, 2007 Page 44 of 61

MA.NUAL: RADIATION CONTROL MANUAL NUMBER: RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 10 OF 16 6.6.5.2. Document the required Enformation on a Hot Particle Briefing Attendance Sheet, RAD-182 (Encdosure 8.1) by checking off each item.

6.6.5.21 An HotALARA Job Ptanning meeting can suffice for a Partide Briefing, 6.6.5.3. Place the completed Hot, Particle Briefing Attendance Sheet in the appropriate RWP File.

Note:

An ALARA Job Planning Meeting held and docunmented in accordance with RP.3151.03, AALARA Job Plannring Guidelines" may be substituted for the requirements of 6.6.5-2 and 6.6.5.3.

6.7. Responae to Hot Particle Detecfon Outside HPZs 6.7-1. Contain/ isolate the pa*rcle(s) and! measure dose! count rates-.

6.7.2. Stop wvork or traffic in the area, if necessary.

6.7.3. Notify RP Supervision-6.7.4. Document required information on survey in accordance with Step 6.5.7 and send particles for analysis as. described in Steps 6.4.4 and 6.4.5.

6.7.5. Perform fol]owvup surveys in the affected area to determine the extent of the Hot Particle problem.

6.7.6. RP Supervision ýWil determine the cause,, it possible, and ýniplement corrective actions such as decontamination or increased survey frequency, if necessary.

6.8. Response to Hot Partices on Personnel Outside HPZs 6.3.1- IE a Hot, Particle is. found on a person who has not been iin an HPZ, THEN decontaminate the 5ndividual.

6.8.2. Notify RP Supe'vis ion.

6.8.3. Perform dose estinmates as required in accordance with RP.3[50.&9D.

April 2, 2007 Page 45 of 61

MANUAL: RADIATION CONTROL MANUAL NUMBER: RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 11 OF 16 6.8.4. Evaluate the situation AUU perfomi follow up surveys to detemline the extent of the problemn (i.e., survey the areas the contamninated individuae had been in or walked through to see if more Hot Particfes are present).

6.8.5. Document suirey information ;in accordance %ithStep 6.5-7 and send particles for analisis p& Steps 6-4-4 and! 6.4.5.

6.9. Response to Hot Particle Detecton in an HPZ 6.9.1. IF Hot Particles greater than 30 mR/hr are found on equipatent or fn the area, THEN isolate and' remove the parcIes to prevent worker contaminriation.

6.9.2. Notify RP Supervision, who wirJ ealuate the need for diecontamination.

6.9.3. Resurvey the affected area to deerenitine the extent of the problem.

6.9.4. Fol]ow guidrance in Section 6.10 if Hot: Particles are found on the workers.

6.10. Response to Hot Partidles on Personnel in an HPZ 6.10.1. IF particles greater than 30 mR/hr [RO-2 (open vndow - closed vrindow, at I1inch)] are detected, THEN have the worker remove the outer Bayer of Protective Clothing and exit the HPZ into Zone 2.

6.10.1.1. Surey the vurker's inner set of PCs to determine the presence of Hot Partidles. IF Hot Paricles are foutnd or suspected, THEN have the worker remove the remaining PCs, cross the SOP to Zone, 1, AND proceed to a PCM-1 B.

6.10.1.2. IF Hot Parac!es are not found or suspected on! the inner layer of PCs, THEN, the worker may don a new set of outer PCs AND return to work.

6.10.1.3 Notify RP Supernsbon 6.10.2. IF a direct OR indirect sur*ey indicates less than 30 mReimhr on the worker, THEN remove amy particles detected ANO the worker may continue.

April 2, 2007 Page 46 of 61

MANUAL: RADIATION CONTROL MANUAL NUMBER: RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 12. OF 16 6.11. Protecte Clothing 6.11-1 The following Protective Clothing may be used for performing work in an HPZ. RP Supervndson will determiine the Protective Clothing requirements for each job evoution.

6.11.1.1. Second, pair of outer coveralls (paper; charkate, plastic, nylon), with all seanis taped (a second pair of cloth caeralls may be allmowed for weldes),.

6.11.1.2. Second pair of rubber gloves taped to outer coveraols 6.11.1.3. Second hood,, securely taped to outer coveralls 6.11.1.4. Respirator taped to outer hood 6.11.1.5. Second pair of high-top booties taped to outer coveralls and flats o'ver the second pair of high-top booties-6.12'. Removal of Contamninated Eouipment from an HPZ.

6.12.1. Alli 'items leaing an HPZ should be wiped down with raisslinn, or eqtuivalent or surveyed directiy for Hot Particles per Section 6.3.

6.12.2. IF no Hot Particles are found. .THEN handle items in accordance wth RP.31)5.0gA.

612.3. Securely package items havtng, or suspected of having, Hot Particles in a double bag, or similar equinpment:

6.12.3.1. Wipe down and survey the exterior of the first bag while in the HPZ.

6.12.3.2. Place the first bag into the second ba in Zone 2. Survey the exterior ofthe second bag to verify surfaces are free from Hot Particles.

6.12.3.3. Use a "Jý seal, or simigar method, to ensure that no [nner surtfaces, of the bags are accessible.

April 2, 2007 Page 47 of 61

NMANUAL: RADIATION CONTROL M'AANUAL NUMBER: RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONITROLS PAGE 13 OF 16 6-12.4. Label the package to inctude at least the following Information (a sticker may be used):

HOT PARTICLE CONTACT mPRhr DATE AND RP TECHNICIAN'S INITILALS 6.13. Personnell Egress from Hot Parlicle Zones 6-13-1. Carefully %%peoff any Respiratory Protection Equipment used, remove outer Protective Clothing and respiratory equirnmnt, AND cross the Step-Off Pad. A RP Technician (if available, see note axove) should assist ýin the removal of Protect.*e Clothing.

6.13.2. Survey the persomel in accordance with Section 6.3.

6.13.2.1- IF no Hot Particles are found, THEN the workers should exit the Hot Particle Buffer Zone.

6.13.2.2. IF Hot Partcltes are found, THEN follow the guidance of Section 6.7.

6_13.3. Survey the removed Protective Clothing and Respiratory Protection Equipment for Hot Particles.

6.13.3.1. IF no Hot Particles are found, THEN put the clothing and resptratry equipment in, nomial receptacfes.

6.13.3.2. IF Hot Partctes are found, THEN, handle the tems in accordance wth Steps 6.12.3 and 612A.

6.14. Hot Particle Trash 6.14-1. IF Not Particles are fou.nd, durring the job, THEN segregate the trash as Hot Particle Trash and handle it,as follows:

April 2, 2007 Page 48 of 61

MTANUAL: RADIATION CONTROL M*ANUAL NUMBER: RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 14 OF 16 6.14.1.1. Survey the package per Sectbon 6-3.

6.14.1.2- Label the package per Step 6-12 6.14.1.3. Store the package in a posted Hot Particle Trash Area.

6.14.1.4. Compact the! Hot Particle Trash separate4, from normal radioactive trash using Hot Partide Contrdls.

6.14.2. IF Hot Particles are not fournd. THEN segregate trash per RP.3a5.09A.

6.15. Deposting Hot Particle Zones 6.15.1- Before removing Hot Particle controls and depicsting an HPZ, RP Supervision must evahrate the status of the work and work area to determTne ifthe: Hot Particle controls can be downgraded.

6.15.2. I.F the potential source of hot Particles is contained, the HPZ is surveyed per Step 6.3 ALfi no Hot Particles are found, THEN! the area may be deposted from HPZ controls prior to continuation of work in the area, with approval by RP Supervision-6.15.3. Do not peform the evaluation vile work is being* prformed in the area.

6.15-4. If this has not already been perfomied, survey Protective 0C1lothing, any tools or euipment, trash containers, and bags for Hot Particles.

This may requEre removing the plasti:c bags from the barrels before performing the surveys.

6.15-5. Document all] survey results per Step 6.5.7-6.15 The approval for retease is to be noted on the RP Log, and ALARA Job Tracking File (AJTF) as appropriate.

April 2, 2007 Page 49 of 61

MANUAL: RADIATION CONTROL MANUAL NUMBER: RP.305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 15 OF 16

7. RECORDS 7.1. The fblurAng indiWual! packagedl documenIs and re~ated correspondence comprneted as a resuli of the perfom-ance or impl=ementatin of this pocedure are records. They, shall be transnmifted to Reeords ManagemenI in accordance with RSAP-rO&D1, Nuclear Records raa.rtg:snment.

7.t.1. Hot Partcle Briefing Attendance. Sheet

8. ENCLOSURES 8.1. Hot Particde Briefing Attendance Sheet (RA1D-182)

April 2, 2007 Page 50 of 61

MANUAL: RADIATION CONTROL MANUAL NUMBER: RP-305.09E REVISION: 4 TITLE: HOT PARTICLE CONTROLS PAGE 16, OF 16 W~T M~T[CLE EIRIrWZNX AYTIUDAI SBUT Tk(SK DE*RCHPrttO:

111o1CAraIM; 04S11IbICM PERfMflEII BY-' ___________

AMHP REQU[IDfNTS: ________

Pf(fIMIC PE MM1EL SLRVEY5. EXPFCTE SP'EM1L SURVEYS: ______

M"S[tM TO 0ISCOVEBF10 09 SUISPECTED HN~ PAWrTICIM$;_______

PADPEJA DRESSINGMURESI4IG PRNCTtI$ ________

BR.IEFIMG 05M'EMeS _________________________

WAD-1B2 Rev. D OFFM~rIVE DATE: %A*j,Vsq5* W 1frIc" ENCLOSURE 8.1 PAGE 1 OF 1 April 2, 2007 Page 51 of 61

Attachment 2 DTBD 06-003, Rev. 2

DTBD-06-003 Rancho Seco Nuclear Generating Station Revision No. 1 Decommissioning Technical Basis Document DPT 06-036 RIC 2A.900 Use of In Situ Gamma Spectroscopy for Final Site Survey PREPARED BY: G.D. Pillsbury Author Date REVIEWED BY:

Technical Reviewer Date REVIEWED BY.

QA Reviewer Date APPROVED BY:

Principal Radiological Engineer Date

1.0 Purpose The purpose of this DTBD is to describe the use of in situ gamma spectroscopy for performing final surveys.

2.0 Discussion The intent is to employ a Canberra characterized HPGe detector (40% rel.

efficiency) coupled to an MCA using Canberra Genie software for performing gamma spectrum analyses of various media for final site surveys. Acquisition of a characterized detector allows the use of the geometry composer software to model actual survey unit conditions in order to obtain accurate gamma survey results. Use of the geometry composer also allows the determination of investigation criteria which will identify the possible presence of an elevated area of residual activity within the detector field of view exceeding the EMC value for the survey medium.

3.0 Definitions Investigation criterion- An activity limit at which further evaluation of the survey data is required. NUREG-1 575, Table 5.8, lists recommended levels for survey unit investigation which are similar to those specified in the RSNGS LTP. The investigation criteria used for in situ measurements is based on preventing the EMC value in a 1 m 2 area from being exceeded; Because the criterion is a derived value rather than a simple multiple of the DCGL, it can be thought of as an "effective" criterion.

4.0 Technical Position In situ gamma spectroscopy can be effectively employed to perform final surveys at MDCs comparable to those typically achieved with hand-held instruments without the possibility of failing to detect an area of elevated2 activity greater than the EMC value. The EMC value is applied to a 1 m land area consistent with NUREG-1575 recommendations given the low dose rates and the very large area factors associated with smaller areas.

In situ gamma spectroscopy can be used for any situation in which the contaminant is a gamma emitter and the source geometry can be defined by the geometry composer.

5.0 Limitations This technical position can only be met using a characterized detector with geometry composer software using approved procedures (Ref. 7.3) unless geometry-specific, NIST traceable calibration sources equal to the size of the detector field of view for each media are obtained. In situ gamma spectroscopy may not be appropriate for performing soil scans in areas

with a risk of discrete particle contamination. Use of 2"x2" Nal detector scans are recommended for this situation.

6.0 Technical Bases Canberra has developed a HPGe detector which has been exposed to gamma sources at multiple points in space in order to determine the detector response to gamma photons which interact with the detector and which originate from any location about the detector. The software uses an iterative discrete ordinate attenuation computation routine to predict the detector response when particular geometry features such as source to detector distances, shielding materials, thickness of source or shield materials, source and shield densities, source to detector angles, and source configurations are entered into the geometry composer. These features allow the same spectrum to be analyzed using more than one geometry. It is this capability which makes possible the identification and evaluation of hot spots using the investigation criterion.

A description and documentation of the characterization of the Canberra HPGe detector (S/N 3920) is contained in Attachment 8.1.

It is anticipated that final surveys will typically be performed with the detector at a distance of 2 m to 3 m from the source with the 90 degree collimator installed. This geometry defines a detector field of view (FOV) of 12 m 2 to 28 M 2 . Due to the critical relationship of the geometries to the analytical results, only approved geometries will be used for FSS surveys.

The gamma spectroscopy analysis report provides the total activity detected within the field of view of the detector and reported in units of pCi/g, pCi/m 2 or dpm/m 2 . For spectra collected using the 90 degree collimator, the FOV is the source to detector distance (which is equal to the radius of the FOV) squared and multiplied by pi.

Concrete source activity depths will typically be set at 2 cm and soil source activity depths will typically be set at 15 cm. These values are consistent with site characterization experience and NUREG-1 575 assumptions. These source geometries allow for the collection of spectra with MDA values for the nuclides of interest (i.e., Cs-1 37 and Co-60) at approximately 0.3 pCi/g for soil and 500 to 1500 dpm/1 00 cm 2 for concrete. Since the MDA values are three percent or less of the respective DCGLs for soils and structure surfaces, the chances of making a Type 1 error is less than 0.05 for reasonable count times of 20 to 60 minutes. The "count to MDA" feature of the Canberra software will be employed to ensure that the desired MDAs are achieved.

Factors Affecting Detector Efficiency

Factors such as sample moisture content, soil density, and overlying water could adversely impact detector efficiency. In situ gamma spectroscopy is typically used as a scanmethod to detect areas of elevated activity, not for direct measurement of soil activity to determine compliance with the DCGLs. Soil density and moisture content don't have a significant effect on scan results. However, the impact is further reduced by using the "massimetric efficiency" for analysis. Use of the "massimetric efficiency" determines efficiency as c/m per unit activity per gram of sample. This means that soil survey depths of 15 cm or more are seen as infinite and soil density can vary by a factor of 2 with no impact on efficiency according to Canberra "Model S573 ISOCS Calibration Software Manual" (pgs. 163, 165).

The soil around the RSNGS site is extremely dry for most of the year. The survey data sheets taken into the field by the survey techs are used to document any standing water found in the scan area so that the geometry can be adjusted to account for the shielding effect. Soil samples used for direct measurements are sieved, dried, and weighed before counting in the lab so their results are not impacted by moisture at all.

Furthermore, the analytical results of NORM in soil scans can be used to identify possible impacts on efficiency so that the geometry can be adjusted to account for such adverse effects. Typical indicator nuclides are K-40 and Pb-212/214.

Investigation Criteria Determination of the Investigation Criteria is based on taking a series of measurements using the detector in a standard geometry, such as a disk, located at a defined distance from the detector. The required geometry parameters are entered into the geometry composer and the acquired spectra are analyzed using the standard geometry. A new ?eometry is then developed which reduces the source to an area of 1 m located at the periphery of the detector field of view. The original spectra are then re-analyzed using the new, small source area geometry (Attachment 8.2).

The ratio of the full field of view activity to the small source activity is determined and the ratio is multiplied by the DCGLEMC for a 1 m 2 area which becomes the Investigation Criterion. Any in situ measurement which equals or exceeds the Investigation Criterion, when analyzed using the full field of view geometry, requires further evaluation to rule out the possibility of a small elevated area of activity within the detector field of view.

For structure surveys, an initial geometry was constructed using a circular plane with a source depth of 2 cm, a radius of 3 m and a source to detector distance of 3 m. A series of spectra were collected using this geometry with the 90 degree collimator attached to the detector. The

spectra were collected from a concrete wall with low, but detectable levels of Cs-137 and Co-60. Analytical results were presented in pCi per m 2 and Cs-1 37 data are shown converted to dpm/100 cm 2 in order to demonstrate the sensitivity of the analyses (Co-60 was not converted due to higher ambient levels of cobalt in the survey area and background was not subtracted from any of the data).

Following the original analyses, the data were re-evaluated using a geometry having a 2 cm thick source of 1 m 2 placed at the periphery of the field of view. The analytical results for the small area sources were compared to the result for the large area sources (i.e., the 28 m 2 field of view). The ratio of the small source to large source activity is the factor by which the DCGLemc must be divided by to derive the Investigation Criterion as shown in the table below.

Table 1. Geometry Comparison For Investigation Criteria Sample #- Nuclide 28 m' source in 28 m2 1 m;' source in Ratio FOV Geometry 28 m 2 FOV (Small to 2

pCi/ m dpm/100 Geometry Large) cm 2 pCi/m 2 CRC002 Cs-137 115684 2568 3058937 26.4 Co--60 922077 24604310 26.7 CRC003 Cs-1 37 30368 674 803012 26.4 Co-60 1182335 31550640 26.7 CRC004 Cs-1 37 84654 1879 2238500 26.4 Co-60 1176505 31394350 26.7 CRC005 Cs-137 646634 14355 17099200 26.4 Co-60 653756 17444690 26.7 CRC006 Cs-137 271698 6032 7184433 26.4 Co-60 708836 18915281 26.7 CRC007 Cs-137 54494 1210 1441027 26.4 Co-60 835538 22298770 26.7 CRC008 Cs-137 36151 803 955918 26.4 Co-60 640738 17097850 26.7 CRC009 Cs-1 37 26204 582 692930 26.4 Co-60 417889 11151050 26.7 CRC010 Cs-137 46540 1033 1230622 26.4 Co-60 1052418 28080790 26.7 CRC011 Cs-137 98584 2189 2606865 26.4 Co-60 965999 25775990 26.7 CRC012 Cs-137 298052 6617 7881140 26.4 Co-60 792048 21134200 26.7 CRC013 Cs-137 434564 9647 11491151 26.4 Co-60 1065999 28444600 26.7 CRC014 Cs-137 230746 5123 6101277 26.4

Co-60 456766. 12186860 26.7 CRC015 Cs-137 607692 13491 16068710 26.4 Co-60 393634 10504530 26.7 CRC016 Cs-1 37 356727 7919 9432931 26.4 Co-60 161815 4316970 26.7 CRC017 Cs-137 309195 6864 8175661 26.4 Co-60 313478 8364573 26.7 CRC018 Cs-137 156929 3484 4149533 26.4 Co-60 770318 20555180 26.7 CRC019 Cs-137 75953 1686 2008371 26.4 Co-60 1048337 27974780 26.7 Mean Cs dpm/100 cm 2 4786 Mean Ratio 26.6 The gross beta-gamma DCGL for structures based on the established nuclide fraction and conditions stated in DTBD 05-015 is 43,000 dpm/100 cm 2. Applying the area factor for a 1 m 2 area of 14.9 results in a DCGLemc of 640,700 dpm/100 cm 2 . The apparent geometry correction factor for a 1 m 2 elevated area at the edge of the detector field of view of 28 m 2 is 26.6 as shown above. Dividing the DCGLemc value by the geometry factor gives an Investigation Criterion of 24,000 dpm/100 cm 2 or 1.08E+6 pCi/mi2 or 3.04e+7 pCi in a 28 M 2 field of view circular plane geometry. This means that as long as the in situ gamma spectroscopy result does not exceed 24,000 dpm/100 cm 2 , there cannot be an undetected elevated area within the field of view of 1 m 2 which exceeds the DCGLemc. Any analytical result greater than the Investigation Criterion would require further evaluation to ensure compliance with the EMC criterion. Investigation measures include, but are not limited to, performing additional surveys using reduced source to detector distances, scanning with 2" by 2" Nal detectors, collecting volumetric samples, or other appropriate measures to detect small, elevated areas within the original FOV.

I The data (Table 2) also indicate that the typical concrete surface MDAs for a 1200 second count of 1318 dpm/100 cm for Cs-137 and 562 dpm/100 cm2 for Co-60 are a small fraction of the surface DCGL of 43,000 dpm/1 00 2

cm Table 2. Concrete Surface 28 m 2 FOV MDA Values Sample # Cs MDA (pCi/mi2 ) Co MDA (pCi/mi2 )

CRC002 66400 23500 CRC003 64900 30300 CRC004 84700 35200 CRC005 60900 26800 CRC006 66600 25800 CRC007 50600 27900 CRC008 49800 20200

CRC009 47900 25000 CRC010 53600 27300 CRC011 56300 26200 CRC012 61800 21900 CRC013 74800 32900 CRC014 54600 18300 CRC015 50900 18100 CRC016 41100 20100 CRC017 52900 17900 CRC018 66500 28800 CRC019 64300 29500 Mean 59397 25317 dpm/100 cm2 1318 562 Soils have been surveyed using in situ gamma spectroscopy with a geometry that evaluates soil activity to a depth of 15 cm over the detector FOV. Soil Investigation Criteria have been determined (Table 3) in a manner similar to that used for structures. The one square meter DCGLEMc for Cs-137 would be 596 pCi/g for a DCGL of 52.8 pCi/g and an area factor of 11.3 and for Co-60 would be 148 pCi/g for a DCGL of 12.6 pCi/g and an area factor of 11.8. The Investigation Criterion for Cs-1 37 is 23.6 pCi/g and for Co-60 is 5.7 pCi/g. The MDAs achievable are on the order of 0.15 pCi/g for Cs-137 and Co-60 which is more than adequate for the soil DCGLs at RSNGS. Investigation Criteria are established to ensure the DCGLEMc will not go undetected in a small elevated area at the edge of the FOV. Given the MDAs and Investigation Criteria for soil, final surveys can be performed on soil with a Type 1 error of 0.05 using in situ gamma spectroscopy for scans.

Table 3. Soil Geometry Comparison Sample Nuclide 28 m2 source in 1 m2 source in Ratio (Small

1. 28 m 2 FOV 28 m2 FOV to Large)

Geometry Geometry (pCi/g) (pCi/g)

$3M005 Cs-1 37 0.376 9.517 25.31 Co-60 <0.220 <5.71 25.95

$3M006 Cs-137 0.480 12.155 25.32 Co-60 <0.152 <3.93 25.86

$3M007 Cs-1 37 0.310 7.842 25.30 Co-60 <0.129 <3.35 25.97

$3M008 Cs-137 0.288 7.298 25.34 Co-60 <0.143 <3.71 25.94

$3M009 Cs-137 0.319 8.072 25.30 Co-60 <0.148 <3.84 25.95

$3M010 Cs-137 <0.167 Obtained background as a

Co-60 <0.138 count S3M011 Cs-137 <0.143 3.624 25.34 Co-60 <0.142 <3.68 25.92 S3M012 Cs-137 0.431 10.923 25.34 Co-60 <0.137 <3.55 25.91 S3M013 Cs-137 0.411 10.412 25.33 Co-60 <0.153 <3.96 25.88 S3M014 Cs-137 0.273 6.910 25.31 Co-60 <0.142 <3.68 25.92 S3M015 Cs-137 0.468 11.841 25.30 Co-60 <0.135 <3.49 25.85 S3M017 Cs-137 0.554 14.018 25.30 Co-60 <0.148 <3.84 25.95 S3M018 Cs-137 0.372 9.416 25.31 Co-60 <0.161 <4.18 25.96 S3M019 Cs-137 0.376 9.527 25.34 Co-60 <0.176 <4.55 25.85 S3M020 Cs-137 0.435 10.022" 25.34 Co-60 <0.147 <3.81 25.92 Mean Cs-137 25.3 Co-60 25.9 As demonstrated above, in situ gamma spectroscopy can be employed for performing final surveys with adequate sensitivity of analysis. For uses not specifically described in this DTBD, a specific geometry (approved per DSIP 0530) must be created, source to detector distances, use of collimation and count times or required MDC must be specified to ensure DQOs are met. When scanning, the MDC achieved must be shown to be less than the DCGLEMc value for the survey unit. Since MDCs similar to those achieved with lab instrumentation can be met with reasonable count times, as long as the correct number of measurements are taken and any adjustment for EMC criteria has been made, use of in situ gamma spectroscopy should be able to achieve Type I and II errors of 0.05. The use of Investigation Criteria ensure that small, elevated areas of activity within the detector field of view will not go undetected or investigated.

7.0 References 7.1 DTBD 05-015, "Structure Nuclide Fractions and DCGLs".

7.2 DTBD 05-014, "Soil Nuclide Fractions and DCGLs".

7.3 DSIP 0530, "Operation of the ISOCS Portable Gamma Spectroscopy System".

8.0 Attachments 8.1 ISOCS Detector Characterization 8.2 Concrete Surface Measurements for Determination of Investigation Criteria 8.3 Soil Measurements for Determination of Investigation Criteria 9.0 RESPONSIBLE INDIVIDUAL George Pillsbury