LIC-15-0113, Response to Interim Staff Evaluation and Request for Additional Information Regarding the Overall Integrated Plan for Implementation of Order EA-12-051, Reliable Spent Fuel Pool Instrumentation

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Response to Interim Staff Evaluation and Request for Additional Information Regarding the Overall Integrated Plan for Implementation of Order EA-12-051, Reliable Spent Fuel Pool Instrumentation
ML15272A415
Person / Time
Site: Fort Calhoun Omaha Public Power District icon.png
Issue date: 09/28/2015
From: Cortopassi L
Omaha Public Power District
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
EA-12-051, LIC-15-0113, TAC MF0968
Download: ML15272A415 (24)
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Text

{{#Wiki_filter:--~.:.. jjjjjjjj Omaha Public Power District 444 South 1ffh Street Mall Omaha, NE 68102-2247 LIC-15-0113 September 28, 2015 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Fort Calhoun Station (FCS), Unit 1 Renewed Facility Operating License No. DPR-40 NRC Docket No. 50-285

Subject:

OPPD Response to Interim Staff Evaluation and Request for Additional Information Regarding the Overall Integrated Plan for Implementation of Order EA-12-051, Reliable Spent Fuel Pool Instrumentation (TAC No. MF0968)

References:

See Enclosure 1 On March 12, 2012, the U.S. Nuclear Regulatory Commission (NRC) issued Order EA-12-051, "Order Modifying Licenses with Regard to Reliable Spent Fuel Pool Instrumentation" (Reference 1), to all power reactor licensees and holders of construction permits in active or deferred status. The Order required licensees to have a reliable indication of the water level in associated spent fuel storage pools capable of supporting identification of the following pool water level conditions by trained personnel:

1. level that is adequate to support operation of the normal fuel pool cooling system,
2. level that is adequate to provide substantial radiation shielding for a person standing on the spent fuel pool operating deck, and
3. level where fuel remains covered and actions to implement make-up water addition should no longer be deferred.

By letter dated February 28, 2013 (Reference 2), the Omaha Public Power District (OPPD) provided its Overall Integrated Plan (OIP) for Fort Calhoun Station, Unit 1, describing how it would achieve compliance with Attachment 2 of Order EA-12-051 by spring 2016. Following an NRC Request for Additional Information (RAI) dated August 23, 2013 (Reference 3), OPPD provided supplemeotal information by letters dated August 28 and October 18, 2013 (References 4 and 5) . The purpose of this letter is to respond to the interim staff evaluation and request for additional information dated November 25, 2013 (Reference 6), which requested that all information be provided by September 30, 2015. OPPD's response is contained in Enclosure 2. Please note that not all information is available at this time. OPPD expects to supplement RAl's 17, 18, and 19 in the spring of 2016, possibly in the 6-Month Status Report due in February 2016. Any significant delays to this schedule will be coordinated with the NRC Project Manager.

U.S. Nuclear Regulatory Commission LIC-15-0113 Page2 If you should have any questions regarding this submittal or require additional information, please contact Mr. Bill R. Hansher at 402-533-6894. There are no regulatory commitments contained in this letter. is true and correct. Executed on Louis P. Cortopassi Site Vice President and CNO LPC/JKG/mle

Enclosures:

1. Reference List
2. Omaha Public Power District Response to NRC Request for Additional Information Related to the Overall Integrated Plan in Response to Order EA-12-051, Reliable Spent Fuel Pool Instrumentation c: M. L. Dapas, NRC Regional Administrator, Region IV C. F. Lyon, NRC Senior Project Manager M.A. Brown, NRC Project Manager S. M. Schneider, NRC Senior Resident Inspector

LIC-15-0113 Page 1 Reference List

1. Letter from NRC (E. J. Leeds I M. R. Johnson) to All Power Reactor Licensees and Holders of Construction Permits in Active or Deferred Status, "Issuance of Order [EA 051] to Modify Licenses with Regard to Reliable Spent Fuel Pool Instrumentation," dated March 12, 2012 (ML12054A679) (NRC-12-0023)
2. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), "Fort Calhoun Station Spent Fuel Pool Instrumentation Overall Integrated Plan," dated February 28, 2013 (ML13059A268) (LIC-13-0011)
3. Email from NRC (Lynnea Wilkins) to OPPD (8. Hansher), "DRAFT: RAI for Fort Calhoun Station Re: Reliable Spent Fuel Pool Instrumentation Order Response (Overall Integrated Plan) (MF0968)," dated August 23, 2013 (ML13235A168} (NRC-13-0107)
4. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), "Omaha Public Power District's First Six-Month Status Report for the Implementation of Order EA 051, Order Modifying Licenses with Regard to Reliable Spent Fuel Pool Instrumentation," dated August 28, 2013 (ML13241A411) (LIC-13-0124)
5. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), "Omaha Public Power District Response to NRC Request for Additional Information Regarding the Overall Integrated Plan in Response to Order EA-12-051 Reliable Spent Fuel Pool Instrumentation," dated October 18, 2013 (ML13294A338) (LIC-13-0144)
6. Letter from NRC (Lynnea Wilkins) to OPPD (L. Cortopassi), "Fort Calhoun Station, Unit No. 1 - Interim Staff Evaluation and Request for Additional Information Regarding the Overall Integrated Plan for Implementation of Order EA-12-051, Reliable Spent Fuel Pool Instrumentation (TAC No. MF0968}," dated November 25, 2013 (ML13317A583)

(NRC-13-0148)

7. 1-0410-9 MOHR SFP-1 Level Probe Assembly Seismic Analysis Report R2 (FC08473)
8. 1-0410-9.5 MOHR SFP-1 Seismic Analysis Report OPPD FT CALHOUN (FC08474)
9. NAl-1725-003 Gothic Study-Hydrodynamic Response in Rectangular Pools (FC08475)
10. NAl-1725-004-Rev-3-Hydrodynamic Response in CGS SFP (FC08476)
11. NAl-1791-011-Hydrodynamic Response in FCS SFP (FC08482)
12. Calculation FC08423, "Evaluation of the Mounting Brackets for the Spent Fuel Pool Level Probe Assembly," Revision O
13. 1-0410-6 MOHR EFP-IL SFPI System Seismic Test Report R1 (SQ-E-775)
14. Engineering Change Number EC 55864, "Spent Fuel Pool Instrumentation - Fukushima"
15. NRC Letter ML14216A362, "Donald C. Cook Nuclear Plant, Units 1 and 2, Report for the Onsite Audit of Mohr Regarding Implementation of Reliable Spent Fuel Pool Instrumentation Related to Order EA-12-051 (TAC Nos. MF0761 AND MF0762)," dated August 27, 2014
16. MOHR Document 1-0410-12, MOHR EFP-IL Signal Processor Operator's Manual
17. MOHR Document 1-0410-13 MOHR EFP-IL Signal Processor Technical Manual
18. MOHR Document 1-0410-14, MOHR SFP-1 Level Probe Assembly Technical Manual

LIC-15-0113 Page 1 Omaha Public Power District Response to NRC Request for Additional Information Related to the Overall Integrated Plan in Response to Order EA-12-051, Reliable Spent Fuel Pool Instrumentation RAl#1 Please provide the results of the calculation to be performed to determine the water elevation necessary for the SFP cooling pump required net positive suction head (NPSH) to confirm that Level 1 has been adequately identified. OPPD Response: Level 1 has been established at elevation 1034'-6.96" (i.e., approximately 1034'-7"), which is equivalent to the current low spent fuel pool (SFP) level alarm. Calculation FC08420, "Net Positive Suction Head Available (NPSHA) of Spent Fuel Pool Circulating Pumps (AC-SA & AC-58)," demonstrates that sufficient net positive suction head is available at this pool level at saturated SFP conditions. The calculation shows that the net positive suction head required (NPSHR) for normal operating conditions is 7 feet of water level above the centerline of the pumps and for saturated conditions is 15.5 feet. For saturated conditions, this corresponds to a plant elevation of approximately 1006'9" which is well below Level 1. Therefore, the requirement of NEI 12-02 is met in that Level 1 probe indication is well above the NPSHR during saturated conditions. RAl#2 Please provide the specific SFP level instrumentation sensor measurement range. OPPD Response: The measurement range of the new spent fuel pool level instrumentation is from approximately 12 +/- 0.5 inches above the top of the fuel racks (plant elevation 1010'-6") to approximately two inches below the spent fuel pool deck (plant elevation 1038'-4"). The total measurable range is approximately 27'-10" and covers the maximum and minimum operating levels. Figure 1 below contains additional details on the range of measurement.

LIC-15-0113 Page2 Fort Calhoun Station N.T.S. Spent Fuel Pool Level Instrumentation Critical Level Elevations _ _.1. - - - E I . 1039'-0" Top of SFP Curb 

                                                               - - - - E l . 1038'-6" Top of SFP Deck
                                                                           & Bottom of Probe Flange
                  - - - - - - - - - - - - - - - +-- El.1037'-9.6" Max Water Level
                  - - - - __ .- - - - - ..... __ - +--         El. 1034'-6.96" Min Water Level I Level 1 Measurable Range 1
             -334"+/-0.5" ..._

(-27'-10"+/-0.5") Probe Length +-- El.1020'-0" Level 2 336"+/-0.5" (28'-0+/-0.5") (__ 

                                                          +--- El. 1011'-0" Leyel 3     __ _
              --- ---                            -F --12" El. 1010"-6"+/-0.5" Tip of Probe   r 18"
           -----------                                  -+---  El.1009'-6" Top of Fuel Racks
                                                                                      -    -    L.

O" I I I I El. 995'-6" Bottom of SFP Figure 1 - SFP Critical Elevations (RAI #2)

LIC-15-0113 Page3 RAl#3 Please provide a clearly labeled sketch or marked-up plant drawing of the plan view of the SFP area, depicting the SFP inside dimensions, the planned locations/placement of the primary and back-up SFP level sensor, and the proposed routing of the cables that will extend from these sensors toward the location of the read-out/display device. OPPD Response: Figure 2 below depicts the requested information. The pool is 20'-7" wide and 33'-0" long. The primary probe is installed near the southwest corner of the pool and the secondary probe is located near the northeast corner of the pool. The cabling for the primary probe is routed along the pool wall and towards the primary indication electronics. The cabling for the backup probe is routed away from the pool and towards the secondary indication electronics.

LIC-15-0113 Page4 

                                                   ~-----

N'JTI 'l7 ...._ Pool Inner Dimensions: 20'-7" x 33'-0" 

                                                                            ._,(reference plant drawing 11405-S-61, file number 16446, rev. 14)

Cabling in conduit towards secondary -- { 

                                                                    ------ - ,-------- ,. -,    r   - ~-
                                                                                                             ----~,         ].
                                                                                                                                                                             ~   I   ,J display electronics
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                                                                                                                      --1'     1" .l 8-CABL£ ROUTED IN I

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l/\!LS.504 SS fUBf 'RACK II Primary Channel Probe I & Cabling  ! NOTE. 21 I 

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Cabling in conduit towards primary 1 I { Q)iI display electronics ~ 4419 , ., I I IN I I! I I I II I I ~ LOCR RCQY El. . I 025'-{) II Reference EC55864 II sketch SK-EC55864-E01 I 

                                                                                                                                                                . .d:.
                                                    -                        ----         - - . _ _ _ _ _ _ _ _ _, _ _ _ _ _ _ _ _ _ . . _ i _ _

GS . ~LAN-~~~ Gb . .* * * -: ~ - ~0~) ll~lX '.I l M~Y BJ! ') l NG r <:.~ F l~OTF -~ l NtJITH ~ " LL . *o*s' o' . -~

  • l02j 0 & ~L
  • CJO. u Figure 2 - SFP Plan View with Probe Locations (RAI #3)

LIC-15-0113 Page 5 RAl#4 Please provide the results of the analyses used to verify the design criteria and methodology for seismic testing of the SFP instrumentation and the electronics units, including design basis maximum seismic loads and the hydrodynamic loads that could result from pool sloshing or other effects that could accompany such seismic forces. OPPD Response: Equipment for level instrumentation consists of probes, remote displays/processors and battery power. Two probes (i.e., SFP-1 Assemblies) are mounted at opposite corners of the pool operating deck and extend into the water. The display and processor units with adjacent battery (EFP-IL enclosures) are mounted to structural components of the auxiliary building in two separate locations. Electrical conduits and cable trays are used for routing of coaxial cables to connect components of the system. Seismic loading and qualification for these items are discussed separately below. SFP-1 Assemblies: The probes are qualified for seismic motion including hydrodynamic conditions that exceed Fort Calhoun Station design basis conditions. Generic testing and analyses were performed or sponsored by Mohr (i.e., the vendor) to levels that bound many nuclear plants including Fort Calhoun Station. Mohr used ANSYS (Reference 7 of Enclosure 1), to evaluate the effect of hydrodynamic loading and the resulting forces, stresses and displacements on the probe assembly. Maximum stresses in the probe are less than material allowable stresses. Mohr also tested the effect of the probe impacting a stainless steel liner. Numerical Applications (NAI) studied (Reference 9 of Enclosure 1) the effect of seismic motion on fuel pools and the associated fluid velocity and sloshing behavior with the objective of demonstrating the capability of GOTHIC for hydrodynamic analysis. Parametric sensitivity studies are included. GOTHIC results (Reference 9 of Enclosure 1) serve as a verification source for conservative analysis with ANSYS as shown in Reference 7 of Enclosure 1. Additionally, NAI provides (Reference 10 of Enclosure 1) vertical fluid velocity that can be used for the design of the probe bracket. Further site-specific analysis using ANSYS with seismic input and pool dimensions for Fort Calhoun Station was performed (Reference 8 of Enclosure 1) to quantify the level of conservatism in the generic analyses. The site-specific analysis reveals lower forces and moments at the probe to bracket attachment point. Additionally, displacements of the probe are less than the available clearance. This result shows that the probe does not impact the pool liner during seismic loading. The design basis maximum seismic loads and the hydrodynamic loads from Reference 8 of are as follows:

LIC-15-0113 Page6 ANSYS Time History, XN/Z Axis, Slosh ON x y z Flange Forces 84 lbf 72.7 lbf -70 lbf Bending Moments 4,434 lbf-in. (about Y) 3,974 lbf-in_ (about X) NIA Peak Displacement 1.67 in_ 1.5 in. NIA Peak Probe Velocity 3.2 ft.ls 3 ft.ls N/A Combined Peak Stresses and Moments (SRSS Method) Flange (0 ft.) 15.5 ksi Shear Force 84.9 lbf Probe Body (-24.4 ft.) 27.3ksi Bending Moment 4,628 lbf-in. Further site-specific analysis was also performed with GOTHIC (Reference 11 of Enclosure 1). Horizontal velocities along the length of the probe are shown to be smaller than the generic results. Slosh height is also shown to be small with no predicted spillage for Fort Calhoun Station. Conclusions from this report are also used for design of the bracket that supports the probe. No direct hydrodynamic loading to the support bracket is required for the predicted slosh height of 0.6 feet. The horizontal fluid velocity profile for Fort Calhoun Station is shown in Figure 3 below.

LIC-15-0113 Page? Ft. Calhoun Scaled Horizontal Maximum Velocity along the Length of the Probe S' t - - - - + - --t -&- 1.41x 4" Max (+) 

                                                           ...- 1.41x4" Max (-)
                                                           -e- 1.41x 8" Max(+)

1.4 1x 8" Max(-) 

                                                           ..... 1.4 1x 12" Max(+) _ _
                                                           -o- 1.41x 12" Max(-)

1.4 1x 24" Max(+) 

                                                           - 1 .4 1x 24" Max(-)
     -6.0      -4.0       -2.0       0.0          2.0         4.0           6.0       8.0 Horizontal Velocity (ft/s)

Figure 3 Site Specific velocity versus depth in pool The probe support bracket is designed (Reference 12 of Enclosure 1) with hydrodynamic probe forces and moments that envelop results tabulated above. Although the probe support is determined to be rigid, peak seismic accelerations and a conservative multi-mode factor is also applied to the support. The combined rotation at the probe support point with probe displacement due to hydrodynamic loading is less than the clearance to the liner. Member stresses and anchor bolt reactions are maintained within design basis allowable values. EFP-IL System and

Enclosures:

The EFP-IL SFPI system is housed in stainless steel National Electrical Manufacturers Association (NEMA) Type 4X enclosures. The signal processor with display is in one enclosure

LIC-15-0113 Page8 and the battery is in a separate enclosure. The enclosures and installed equipment were seismically tested in accordance with IEEE 344-2004 to seismic levels that bound the Fort Calhoun Station (Reference 13 of Enclosure 1). Functional testing was performed before and after the seismic test. Visual monitoring and analysis of equipment log entries were used to confirm continuous function during the tests. No deficiencies were identified. Mounting details for the enclosures were evaluated (Reference 14 of Enclosure 1) to ensure consistency with seismic testing (Reference 13 of Enclosure 1). Electrical Conduits: Conduit and conduit supports are installed per station procedures to ensure conservative seismic capacity. RAl#5 For each of the mounting attachments required to fasten SFP level equipment to plant structures, please describe the design inputs, and the methodology that was used to qualify the structural integrity of the affected structures/equipment. OPPD Response: The SFP level probe mounting brackets will be attached to the in-place SFP deck structure using stainless steel concrete expansion anchors (CEAs) consistent with plant procedures for Seismic Class I CEAs. Design inputs include the weight of the probe and forces on the probe as determined by vendor analyses including seismic and pool sloshing effects. The design provides assurance by evaluation, including calculation and analysis, that the structural integrity of the SFP deck and overall structure is not adversely affected by this attachment. The probe bracket mounting analysis is captured in plant calculation FC08423 (Reference 12, Enclosure 1). The mounting of the remaining components to in-place structures and components was evaluated in engineering change (EC) 55864 (Reference 14, Enclosure 1), Section 4.1.38 "Civil/Structural Requirements," and Section 8, "Design Considerations Summary." The other components that are attached to plant structures include conduit supports, tube track for the hardline cable on the SFP deck, and the SFPI indicator and battery enclosures. Design inputs include weights of vendor equipment from manuals and published literature, accepted plant seismic spectra, mounting configurations from successful vendor seismic qualification testing, and plant design standards. The components associated with the new SFP instrumentation (SFPI) system are mounted in accordance with plant seismic criteria and are evaluated using the applicable seismic spectra for the area where they are installed. EC 55864 evaluated the capability of the mounting configuration as well as the impact on the in-place structure. The impact of the new components on the in-place structure was determined to be insignificant due to the minimal weight added. The structure has adequate margin and is acceptable. RAl#6 Please provide analysis of the maximum expected radiological conditions (dose rate and total integrated dose) to which the sensor electronics (including power boxes, signal

LIC-15-0113 Page 9 processors, and display panels) will be exposed. Also, provide documentation indicating the maximum total integrated dose the sensor electronics can withstand and how it was determined. Discuss the time period over which the analyzed total integrated dose was applied. OPPD Response: Radiological Conditions to Which the Sensor Electronics will be Exposed Regarding the level sensor (Mohr Probe), and level sensor electronics housed in the probe head above the SFP, Calculation FC08287 titled "NEI 12-02 Rev. 1, Spent Fuel Pool Exposure and Exposure rates using an off-loaded core with 72 hrs of decay" was performed. This site specific calculation was performed to generate dose rates, and 7-day integrated exposures as a function of probe location to the water level. This site specific calculation documented conservative estimates of radiation exposure to a sensor, transmitter, or any other piece of equipment near the surface of the pool water. The 30-year integrated exposure to the probe at Level 3 is < 9 x 108 Rads and < 9,000 Rads at Level 2 and Level 1. Note, the integrated exposures are based on exposure rate at the top of the fuel storage racks and are conservative, because the polyether ether ketone (PEEK) insulators in the probe are estimated to be three (3) to five (5) feet above the racks. The 7-day integrated exposure plus the 30-year exposure was calculated to be 8.89 x 108 Rads at Level 3, 1.31 x 106 Rads at Level 2, and 3.25 x 105 Rads at Level 1 (dose points were approximate to finalized level elevations). All exposures were less than the noted 10 GRad for PEEK insulators in the probe documented in the 1-0410-2 "MOHR SFP-1 Level Probe Assembly Materials Qualification Report," which was audited and documented in the DC Cook Bridging Document between Vendor Technical Information and NRC Vendor Audit. The Total integrated dose (TIO) noted above is the total of a 30-year dose plus the 7-day worst case accident dose (Level 3) at the lowest spacer location on the probe body. The level sensor electronics housing - probe head is located above the SFP. The level sensor electronics are located at approximately the same elevation as the SFP deck. For conservatism and comparison, it was noted that the 7-day integrated exposures plus the 30-year exposure at Level 1 was 3.25 x 105 Rads. The actual probe head is located above this elevation and as such would see a lower TIO. For comparison purposes, the Level 1 dose is utilized and this TIO is less than the threshold dose stated in 1-0410-2 titled "MOHR SFP-1 Level Probe Assembly Materials Qualification Report" (PEEK: 10 GRad, EPDM 2 GRad, and Sylgard 170: 200 MRad). Maximum dose rates as a function of water level elevation, exposure point were performed for the accident scenario and are documented in Calculation FC08287. The 168-hour integrated dose at Level 3 with water at the top of the racks is 4.31x106 R. The dose rate at Level 2 was calculated to be 54 mR/hr if the water level is at Level 2, and 7.78x103 R/hr if the water level is at the top of the racks. The calculated radiological conditions at Level 2 illustrate the ability of water shielding levels to lower exposure rates. Table 1 of Calculation FC08287 documents various elevations, exposure points and resultant dose rates, and 168-hour TIO (at water level and at top of the fuel racks). Regarding the signal processors, display panels and battery, Calculation FC08403,"Qualitative evaluation of radiation dose on the spent fuel pool level instrumentation displays, process and

LIC-15-0113 Page 10 battery performed an analysis of radiation dose that may affect the reliability of the instrument displays, processor and back-up battery. The calculation demonstrated that the expected radiation exposure over the life of the instrumentation would be significantly below the level of radiation that would make the instrumentation unreliable. A reliability threshold dose of 10,000 Rad was estimated for the sensor electronics (including power boxes, signal processors, and display panels). The calculation performed an evaluation of the radiation environment on the upper floor of the auxiliary building (i.e., Room-69) from scattered radiation as a result of the accident exposure for beyond design basis event. The primary display would be installed in Room-30 1 , which is one floor below Room-69. Additional shielding is provided for the display and electronics versus calculated requirements. The secondary display is to be installed in Room-57, which is the alternate shutdown panel area and outside the radiation controlled area and as such, is considered a mild environment with no anticipated radiation affects. The radiation exposure for the primary display is from a freshly discharged core of spent fuel with 72 hours decay, immersion in contaminated air from a boiling spent fuel pool was also considered, and normal exposure from plant operations. The calculated dose is very conservative and assumes three different conditions are occurring at once: 1) the core in the spent fuel pool is uncovered at the top of active fuel with just 72-hours of decay; 2) the spent fuel pool is boiling; and 3) the equipment has been irradiated for 40-years prior the event. If the water level in the spent fuel is 10-feet or greater above the fuel racks, dose rates from direct exposure within Room-69 are insignificant (i.e., < 1-mr/hr). Therefore, the major exposure prior to water lowering to the top of active fuel is immersion in contaminated air. The exposure from contaminated air is a small fraction of the direct radiation exposure. Summing the three individual pathways of radiation exposure is therefore a conservative dose estimate. The table below provides results of dose rates and total integrated dose as a function of distance from the spent fuel pool in Room-69 (Note, the display, battery enclosure and processor) is to be installed in the floor below Room-69 and a further distance from the pool with additional floor thickness for shielding (i.e., 24" thick). The results show the total dose from normal operations and an accident exposure is 216-Rad in Room-69 a distance of about 102 feet from the edge of the SFP. Various other dose rates and integrated dose is calculated and illustrated in the table below. 1 Room-30 was chosen since only abandoned in place equipment (AIPE) is in the room behind the shield wall.

LIC-15-0113 Page 11 Table: Dose and Dose Rates at various distances from the Spent Fuel Pool in Room-69 Exposure Time (hrs) Immersion Dose Rate 12 24 72 168 Operating Dose (mRad/hr): 1.23E+OO 2.47E+OO 7.39E+OO 1.73E+01 1.75E+05 mRad Distance Direct Dose Dose Dose Dose Dose Percent of Exceed fromSFP Rate (mRad) (mRad) (mRad) (mRad) Threshold Threshold Edge (ft) (mRad/hr) !25.0 1.09E+03 1.88E+05 2.01E+05 2.54E+05 3.61E+05 3.61% No 50.0 4.94E+02 1.81 E+05 1.87E+05 2.11 E+05 2.61E+05 2.61% No a6.a 3.61E+02 1.80E+05 1.84E+05 2.02E+05 2.39E+05 2.39% No 83.5 2.84E+02 1.79E+05 1.82E+05 1.96E+05 2.26E+05 2.26% No 101.9 2.27E+02 1.78E+05 1.81E+05 1.92E+05 2.16E+05 2.16% No Threshold:> 10,000-Rad {1x107-mRad) Room-30 is an enclosed room a floor below Room-69 and therefore it is reasonable to conclude that the dose in Room-30 from a loss of spent fuel cooling event would be equal to or less than the dose in Room-69. Operational dose was also included for installation of the processor, display, and battery in Room-30. The operational dose was based upon plant surveys, and conservative photon energies (i.e., 137-Cs) was calculated to be 205 Rads (total operational exposure to equipment for a 40-year integrated dose). The operational dose for the Room-30 processor, display, and battery is slightly higher than that for Room-69, however, the accident dose would be attenuated by the 24-inch thick floor slab, and shield walls around Room-30, and as such, it is considered that the Room-69 integrated dose noted above would be comparative. The total integrated dose including operational dose would be about 205 Rads for the Room-30 display location. As stated above, the secondary display will be installed in Room-57, which is the alternate shutdown panel area and a mild environment with no anticipated radiation affects as the room is outside the radiological controlled area. Maximum Total Integrated Dose that the Sensor Electronics can Withstand The sensor components in the SFP area (submerged portion of probe body were assessed in 1-0410-2 "MOHR SFP-1 Level Probe Assembly Materials Qualification Report." The material identified to be sensitive to irradiation are PEEK insulators (1 O GRad). This information was also provided in the DC Cook Bridging Document related to item number 4, NRC Vendor Audit. As such, the threshold for the sensor components is based upon the lowest material threshold which is PEEK at 1O GRad, documented in the Mohr vendor report noted above. The sensor electronics housing contains materials that were assessed in 1-0410-2 "MOHR SFP-1 Level Probe Assembly Materials Qualification Report". The materials that were identified to be sensitive to irradiation were noted (PEEK: 10 GRad, ethylene propylene diene (EPDM): 2 GRad, and Sylgard 170: 200 MRad) . This information was also provided in the DC Cook Bridging Document related to item number 5, NRC Vendor Audit. As such, the threshold for the

LIC-15-0113 Page 12 sensor electronics housing is based upon the lowest material threshold which is Sylgard 170 at 200 MRad, documented in the Mohr vendor report noted above. The electronics enclosure in Room-30 with display and battery, were evaluated utilizing public literature to derive a maximum total integrated dose threshold. The display system contains various microelectronics, which are typically made of various materials such as mixed oxide semiconductors (i.e., silicon, polysilicon, and silicon dioxides, ruthenium oxides, and other glass materials). Circuit boards are also made of conductive materials such as copper, tin, and zinc (possible doped materials such as gold and palladium may be included). The evaluation for the Room-30 display and electronics was based upon public literature data, research reports from CERN (the European Organization for Nuclear Research), Sandia National Laboratories, the Electric Power Research Institute (EPRI), and Texas Instruments. A sampling of documents are identified which were reviewed:

1. AN-925 Radiation Design Test Data for Advanced CMOS Product, Literature Number SNPA253A, Texas Instruments, January 1994,
2. AN-924 Dose Rate Response of Advanced CMOS Products, Literature Number SNOA252A, February 1994, "Effect of Nuclear Radiation on Semiconductor Devices, (U)" WT-1489, Haas, P., Shaull, J., Behrens W., (339501 L), October 7, 1960, Sandia National Laboratories.

These documents point out that microelectronic components typically do not exhibit damage until gamma doses exceed 10,000 Rads. Various plastics that could be utilized in the display or enclosures typically have gamma radiation thresholds much higher than 10,000 Rads and would exhibit dimensional stability and radiation resistance as documented in EPRI report, "Radiation Effects on Organic Material in Nuclear Power Plants", November 1981, (NP-2129). Time Period over Which the Analyzed Total Integrated Dose was applied The total integrated accident dose was analyzed at four time points 12, 24, 72, and 168 hours. This integrated dose included a 40-year total normal operational dose prior to the accident for Room-30 components. The total integrated dose included a 30-year total normal operational dose prior to the accident for the SFP components. A 30-year total normal operational dose consideration for the SFP components would not result in exceeding the PEEK material threshold. RAl#7 Please provide information indicating the maximum expected ambient temperature in the room in which the sensor electronics will be located under BOB conditions, in which there is no ac power available to run heating, ventilation, and air conditioning (HVAC) systems, and whether the sensor electronics are capable of continuously performing required functions under this expected temperature condition. OPPD Response: Plant calculation FC08354, "Control Room Heatup Calculation for Extended Loss of AC Power (ELAP)," was developed in part to determine the environmental conditions in Room-30 and Room-57 of the auxiliary building following a Beyond-Design-Basis External Event (BDBEE) resulting in an ELAP. The calculation documents a plant model made using the GOTHIC

LIC-15-0113 Page 13 computer program. The model was modified to account for reduced heat loads in the auxiliary building rooms, increased containment temperature, and the BDBEE conditions at the spent fuel pool area, which include a boiling water and/or steam environment. The primary and secondary spent fuel pool level sensor electronics are located in Room-30 and Room-57, respectively. The results of this calculation show that Room-30 reaches a maximum temperature of 117 degrees Fahrenheit and Room-57 reaches a maximum temperature of 112 degrees Fahrenheit (Reference Section H6.1.1 of calculation FC08354 (page H9 of H 14)). These temperatures are within the maximum temperature limits for the sensor electronics, as provided by the vendor (MOHR). Based on objective evidence obtained during testing and as stated in MOHR Document 1-0410-1, "MOHR EFP-IL SFPI System Temperature and Humidity Test Report", Rev. 1, normal system operation of the sensor electronics is demonstrated at -10 to 55 degrees Celsius which corresponds to approximately 14 to 131 degrees Fahrenheit. RAI #8 Please provide information indicating the maximum expected relative humidity in the room in which the sensor electronics will be located under BOB conditions, in which there is no ac power available to run HVAC systems, and whether the sensor electronics are capable of continuously performing required functions under this expected humidity condition. OPPD Response: Plant calculation FC08354, "Control Room Heatup Calculation for Extended Loss of AC Power (ELAP)," was developed in part to determine the environmental conditions in Room-30 and Room-57 of the auxiliary building following a Beyond-Design-Basis External Event (BDBEE) resulting in an ELAP. The calculation documents a plant model made using the GOTHIC computer program. The model was modified to account for reduced heat loads in the auxiliary building rooms, increased containment temperature, and the BDBEE conditions at the spent fuel pool area, which include a boiling water and/or steam environment. The primary and secondary spent fuel pool level sensor electronics are located in Room-30 and Room-57, respectively. The results of this calculation show that the relative humidity of Room-30 and Room-57 do not increase from their initial conditions of 35% and 76%, respectively. Although the SFP is postulated to be boiling, Room-30 has no open flow path to that environment and Room-57 is far enough away from the SFP such that steam does not enter the room (Reference Section H6.1 .2 of FC08354 (page H 1o of H14)). These relative humidity values are within the limits for the sensor electronics, as provided by the vendor (MOHR). Based on objective evidence obtained during testing and as stated in MOHR Document 1-0410-1, "MOHR EFP-IL SFPI System Temperature and Humidity Test Report", Rev. 1, normal system operation of the sensor electronics is demonstrated at 5 to 95% relative humidity. RAl#9 Please provide information describing the evaluation of the comparative local electronics cabinet and display panel ratings against postulated plant conditions. Also, please

LIC-15-0113 Page 14 provide results of the manufacturer's shock and vibration test methods, test results, and the forces and their frequency ranges and directions applied to the display panel associated with its successful tests. Include a description of the specific method or combination of methods to be applied to demonstrate the reliability of the permanently installed local and electronics cabinet equipment under BOB shock and vibration conditions. OPPD Response: The vendor's shock and vibration test report is MOHR Report Number 1-0410-5, "EFP-IL SFPI System Shock and Vibration Test Report." This report contains the vendor's test methods, test results, the forces, frequency ranges, and directions applied to the display panel. This report documents that the local electronics display panel will continue to function after being subjected to shock and vibration. This test report was reviewed, accepted, and incorporated into plant calculation FC08472. As part of the review and acceptance of the test report, a comparison of the levels tested against postulated plant conditions was made and they were found to be acceptable. RAI #10 For RAI #9 above, please provide the results for the selected methods, tests and analyses used to demonstrate the qualification and reliability of the installed equipment in accordance with the Order requirements. OPPD Response: The results are included in the following reports from MOHR Test and Measurement LLC (those noted with asterisk were provided to the NRC as part of the Bridging Document Between Vendor Technical Information and Licensee Use Based on NRC Staff Requests for Additional Information (RAls) and NRC Vendor Audit-DC Cook Audit, Reference 15, Enclosure 1). The three (3) non-asterisked reports at the end of the table contain information proprietary to Mohr or Numerical Applications and OPPD does not have permission at this time to release them. Report No. Title 1-0410-1* MOHR EFP-IL SFPI System Temperature and Humidity Test Report 1-0410-2* MOHR SFP-1 Level Probe Assembly Materials Qualification Report 1-0410-3* MOHR EFP-IL SFPI System Proof of Concept Report 1-0410-4* MOHR EFP-IL SFPI System EMC Test Report 1-0410-5* MOHR EFP-IL SFPI System Shock and Vibration Test Report 1-0410-6* MOHR EFP-IL SFPI System Seismic Test Report 1-0410-7* MOHR EFP-IL SFPI System Battery Life Report 1-0410-8* MOHR EFP-IL SFPI System Boric Acid Deposition Report 1-0410-9* MOHR SFP-1 Level Probe Assembly Seismic Analysis Report 1-0410-10* MOHR EFP-IL SFPI System Power Interruption Report

LIC-15-0113 Page 15 1-0410-11* MOHR EFP-IL SFPI Svstem Software Verification and Validation 1-0410-12* EFP-IL SiQnal Processor Manual 1-0410-13* EFP-IL Signal Processor Technical Manual 1-0410-14* SFP-1 Level Probe Assembly Technical Manual 1-0410-15* MOHR EFP-IL SFPI System Uncertainty Analysis 1-0410-16* MOHR SFP-1 Level Probe Assembly Shock and Vibration Test Report EVAL-194-4812-01

  • MOHR EFP-IL Liquid Level Measurement System Failure Modes and Effects Analysis (FMEA)

FC08475 GOTHIC Verification and Sensitivity Studies for Predicting (NAl-1725-003*) Hydrodynamic Response to Acceleration in Rectangular Shaped Pools FC08476 Seismic Induced Hydraulic Response in the CGS Spent Fuel Pool (NAl-1725-004*) FC08474 MOHR SFP-1 Site-Specific Seismic Analysis Report: OPPD (FCS) (1-0410-9.5) FC08482 Seismic Induced Hydraulic Response in the Ft. Calhoun Spent Fuel (NAl-1791-011) Pool 1-1010-2 Qualification Report: EFP-IL MOD-1 Modification Package RAI #11 Please provide analysis of the vendor analysis and seismic testing results and show that SFP level instrument performance reliability, following exposure to simulated seismic conditions representative of the environment anticipated for the SFP structures at FCS, has been adequately demonstrated. OPPD Response: See response to RAI #4. RAI #12 Please provide the following: a) A description of the manner in which the two channels of the proposed level measurement system meet this independence requirement, to minimize, to the extent practicable, the potential for a common cause event to adversely affect both channels. b) Further information describing how each level measurement system, consisting of level sensor electronics, cabling, and readout devices will be designed and installed to address independence through the application and selection of independent power sources, the use of physical and spatial separation, independence of signals sent to the location(s) of the readout devices, and the independence of the displays. (This information was previously requested as RAl-5 in the NRC letter dated August 23, 2013.)

LIC-15-0113 Page 16 OPPD Response: a) The new instrumentation system will consist of two separate and identical channels, primary instrument channel and a secondary instrument channel. Each channel will have its own SFP-1 level probe, interconnecting cabling, and EFP-IL signal processor, monitor, and uninterruptable power supply (UPS) battery. The normal power supply to the instruments will be provided by different 120VAC power sources such that a loss of a distribution panel or will not result in the loss of both channels. During a BDBEE, each channel has independent battery systems that will supply the channels with power for at least seven (7) days. The primary indicator and battery will be located in Room-30. The secondary indicator and battery will be located separately in Room-57, near the alternate shutdown panel. Cables for each channel are routed in separate conduits and cable trays. b) The probes for the two channels are installed in opposite corners of the spent fuel pool. Each of the two level probes contain an integral hard line coaxial cable that is routed to a local junction box where it transitions to a field-routed coaxial cable that goes to each respective level electronics package in the respective auxiliary building locations described above. The hard line coaxial cable is routed through tube tracks. The primary and secondary channel cables are routed in separate conduits through different sides of the spent fuel pool throughout the pool area. This separation distance is maintained to the respective electronics enclosure locations in the auxiliary building. The arrangement for the probe maintains separation and takes advantage of inherent design features of the pool structure to provide protection from missiles and debris. The design provides two identical non-safety related wide range level instruments that are connected with physically separated non-satety related cabling to indicators located in separate areas of the auxiliary building. This arrangement provides a highly reliable remote display of SFP water level. Physical separation of the two channels is accomplished by the diversity of the SFP locations and by separately routing of interconnecting cabling. RAI #13 Please provide the following: a) A description of the electrical ac power sources and capabilities for the primary and backup channels. b) The results of the calculation depicting battery backup duty cycle requirements, demonstrating battery capacity is sufficient to maintain the level indication function until offsite resource availability is reasonably assured. (This information was previously requested as RAl-6 in NRC letter dated August 23, 2013. However, based on feedback from the licensees, it was revised as above.) OPPD Response: a) The level indicating channels will be installed as an independent and redundant system. Each channel will be powered by an independent 120VAC source. Each channel will be provided with an uninterruptible power supply (UPS) battery capable of powering the channel for at least seven (7) days.

LIC-15-0113 Page 17 The 120VAC normal power feeds for each channel are provided from distribution panels near each channel indicator located in the auxiliary building. Each channel will receive normal power from a separate inverter powered by a separate DC Bus. Thus, a loss of one of the inverters or buses does not result in a loss of the normal 120VAC power for both instrument channels. On loss of normal 120VAC power, each channel's UPS automatically transfers to a dedicated backup battery. If normal power is restored, the channel will automatically transfer back to the normal AC power. Each backup battery is maintained in a charged state by a commercial grade UPS. The batteries are capable of powering the channel for at least seven (7) days of monitoring operation. This provides adequate time to allow the batteries to be replaced with a spare charged battery or connected to a portable generators as off-site resources can be deployed in accordance with the mitigating strategies resulting from Order EA-12-049. b) The sample rate estimates have been developed by the vendor using conservative instrument power requirements and measured battery capacity with draw-downs during and following exposure of the batteries to their maximum operating temperature for up to seven (7) days. The instrument configuration is planned for an automated sample rate when under battery power consistent with seven (7) days of continuous operation. Permanent installed battery capacity for seven (7) days continuous operation is planned consistent with NEI 12-02 duration without reliance on or crediting of potentially more rapid power restoration from the flexible strategies (FLEX) program. Batteries are readily replaceable via spare stock without the need for recalibration to maintain accuracy of the instrument. These measures ensure adequate power capacity and margin. The vendor's battery capacity tests are documented in report 1-0410-7, "MOHR EFP-IL SFPI System Battery Life Report." RAI #14 Please provide analysis verifying that the proposed instrument performance is consistent with these estimated accuracy normal and BOB values. Demonstrate that the channels will retain these accuracy performance values following a loss of power and subsequent restoration of power. OPPD Response: The stated accuracy of the vendor's system is +/-3 inches, which is within the accuracy requirements of +/-12 inches as stated in NEI 12-02. The vendor has performed testing on multiple SFPI units to verify that the accuracy of the instrument is maintained within the stated ranges. The report contains analysis documenting how external factors that may contribute to measurement uncertainty as a result of BDBEE are successfully mitigated by the SFPI system components. This testing and analysis is documented in report 1-0410-15, "MOHR EFP-IL SFPI System Uncertainty Analysis." Instrument accuracy and performance are not affected by restoration of power or restarting the processor. A summary of power interruption testing is documented in report 1-0410-1 O, "MOHR EFP-IL SFPI System Power Interruption Report." Power interruption testing was performed during/after safe shutdown earthquake (SSE) events during seismic testing, after each

LIC-15-0113 Page 18 sequence of shock and vibration testing, and at each temperature and humidity test point during environmental testing. RAI #15 Please provide a description of the methodology to be used for determining the maximum allowed deviation from the instrument channel design accuracy that will be employed under normal operating conditions as an acceptance criterion for a calibration procedure to alert operators and technicians that the channel requires adjustment to within normal design accuracy. OPPD Response: The vendor provided design accuracy value of +/- 3 inches will be used as the acceptance criterion for calibration. No additional deviation will be allowed. This accuracy value includes margin from the expected accuracy at normal water levels. The vendor has documented the testing to validate the expected design accuracy of +/-3 in vendor report 1-0410-15, "MOHR EFP-IL SFPI System Uncertainty Analysis." The testing showed a worst-case deviation of 2.5 inches at six (6) inches from the end of the probe. The performance generally was better near the probe flange. The SFP level is allowed to vary during normal operation from approximately 8.5 inches to 47 inches below the probe flange. Therefore, the design accuracy value of+/- 3 inches is not expected to be exceeded. RAI #16 Please provide a description of the in-situ calibration process at the SFP location that will result in the channel calibration being maintained at its design accuracy. OPPD Response: Periodic testing and calibration of the SFP level instrumentation will be established in conjunction with the requirements of the vendor technical manuals (References 16, 17, and 18 of Enclosure 1). The vendor's Operator's Manual (Reference 16 of Enclosure 1) provides description of the capability and provisions the proposed level sensing equipment will have to enable periodic testing and calibration, including how this capability enables the equipment to be tested in-situ. The NRG staff audited the instrumentation design at the vendor's facility during the week of May 26, 2014 and issued its audit report (Reference 15 of Enclosure 1). Section 4 of the NRG audit report addresses in part, Calibration and Testing, and states, in part, the following: A. MOHR Reports (References 16, 17, and 18 of Enclosure 1) "provide the testing and calibration procedures for the SFPI. MOHR's SFPI design can be calibrated in-situ without removal from its installed location." B. Reference 17 of Enclosure 1, Section 6.5, "Calibration" provides recommended calibration intervals to be followed by users of this technology. C. The NRG staff found the instructions and recommendations for calibration of the SFPI to be thorough and user-friendly."

LIC-15-0113 Page 19 The instructions in the vendor manuals will be incorporated into a new calibration and testing procedure for the system. RAI #17 Please describe the evaluation used to validate that display locations can be accessed without unreasonable delay following a BOB event. Include the time available for personnel to access the display as credited in the evaluation, as well as the actual time (e.g., based on walk-throughs) that it will take for personnel to access the display. Additionally, please include a description of the radiological and environmental conditions on the paths personnel might take. Describe whether the display location remains habitable for radiological, heat and humidity, and other environmental conditions following a BOB event. Describe whether personnel are continuously stationed at the display or monitor the display periodically. OPPD Response: Details regarding the actual time to access the display will be established when the FLEX Support Guidelines are validated, which is planned for February 2016. The worst case environmental conditions have been established and documented in calculation FC08354 for temperature and humidity for the locations of display and/or monitoring and would be habitable for periodic monitoring. The radiation dose rates for Room-30 have been established in calculation FC08403 based on various scenarios and indicate that it would remain habitable from a radiation dose aspect as well (normal dose rate is< 0.5 mr/hr, for BDB (Beyond Design Basis) event, the dose rates would not pose a significant hazard to an operator responding to such an event). OPPD intends to supplement this response in the spring of 2016 possibly in the six-month status update report due in February 2016. RAI #18 Please describe the activities for which personnel will be trained, such as use of the instrument channels, provision of alternate power, calibration and surveillance. Describe the approach to training used to identify the population to be trained and determined the initial and continuing elements of the required training for the SFP instrumentation. OPPD Response: Training activities are being determined and developed. The Mohr vendor training is anticipated to be performed in November 2015 at the factory and will include addressing instrument channels, provision of alternate power, calibration and surveillance. The FCS Training Department is identifying the population to be trained regarding initial and continuing elements of training for the SFP instrumentation. OPPD intends to supplement this response in the spring of 2016 possibly in the six-month status update report due in February 2016. RAI #19 Please provide a list of the procedures addressing operation (both normal and abnormal response), calibration, test, maintenance, and inspection that will be developed for use of the SFP instrumentation. The licensee is requested to include a brief description of the specific technical objectives to be achieved within each procedure.

LIC-15-0113 Page 20 OPPD Response: A new calibration/maintenance procedure IC-CP-01-4356/4357 is being finalized that will contain the necessary steps for routine testing, calibration and maintenance of the primary and secondary spent fuel pool level instrument channels to maintain the instrument channels at the design accuracy. MOHR has provided documentation that was used as input in the creation of this procedure. A draft of this procedure has been included with EC55864. Operating procedures, both normal and abnormal response, are still in development and are being coordinated with the flexible mitigation strategies required under Order EA-12-049. OPPD intends to supplement this response in the spring of 2016 possibly in the six-month status update report due in February 2016. RAI #20 Please provide the following: a) Further information describing the maintenance and testing program to be established and implemented to ensure that regular testing and calibration is performed and verified by inspection and audit to demonstrate conformance with design and system readiness requirements. Include a description of plans to ensure necessary channel checks, functional tests, periodic calibration, and maintenance will be conducted for the level measurement system and its supporting equipment. b) A description of the compensatory actions that will be taken in the event that one or both channels are non-functioning, as described in the guidance in NEI 12-02 Section 4.3. OPPD Response: a) Functional checks are automated and/or semi-automated and are performed through the instrument menu software and initiated by the operator. There are a number of other internal system tests that are performed by system software on an essentially continuous basis without user intervention but can also be performed on an on-demand basis with diagnostic output to the display for the operator to review. Functional checks are described in detail in the vendor's manuals, and the applicable information is planned to be incorporated in plant procedures and preventive maintenance tasks. Functional tests are planned to be performed periodically at frequencies equivalent to or more often than vendor requirements. Channel calibration tests per maintenance procedures with limits established in consideration of vendor equipment specifications are planned to be performed at frequencies established in consideration of vendor recommendations. SFPI channel/equipment maintenance/preventative maintenance and testing program requirements to ensure design and system readiness are planned to be established in accordance with Fort Calhoun Station processes and procedures. Vendor recommendations will be considered to ensure that appropriate regular testing, channel checks, functional tests, periodic calibration, and maintenance is performed (and available for inspection and audit). These maintenance and testing program requirements will be developed during the SFPI modification design process.

LIC-15-0113 Page 21 b) Both SFPI channels incorporate permanent installation of relatively simple and robust equipment. Permanent installation, coupled with stocking of adequate spare parts reasonably diminishes the likelihood that a single channel (and greatly diminishes the likelihood that both channels) will be out-of-service for an extended period of time. The primary or back-up instrument channel can be out of service for testing, maintenance, and/or calibration for up to 90 days provided the other channel is functional. Additionally, compensatory actions must be taken if the instrumentation channel is not expected to be restored or is not restored within 90 days. For a single channel that is not expected to be restored, or is not restored within 90 days, the compensatory actions will include steps necessary to ensure availability of normal alarms and proper function of the remaining indication channel validated by direct visual monitoring. If both channels become non-functional, then actions will be initiated within 24 hours to restore one of the instrumentation channels and to implement compensatory actions within 72 hours. Compensatory actions include steps necessary to ensure availability of normal alarms and increased direct visual monitoring of SFP level.}}

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