ML19092A332

Response to Request for Additional Information for Proposed Technical Specification Changes for Spent Fuel Pool Storage and New Fuel Storage

ML19092A332
Person / Time
Site:	Millstone
Issue date:	03/27/2019
From:	Mark D. Sartain Dominion Energy Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML19092A332 (28)

Text

Dominion Energy Nuclear Connecticut, Inc.

5000 Dominion Boulevard, Glen Allen, VA 23060 Dominion Energy.com U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 March 27, 2019 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 Serial No.

NRA/SS Docket No.

License No.19-077 RO 50-423 NPF-49 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR PROPOSED TECHNICAL SPECIFICATION CHANGES FOR SPENT FUEL POOL STORAGE AND NEW FUEL STORAGE By letter dated May 3, 2018, Dominion Energy Nuclear Connecticut, Inc. (DENG) requested Nuclear Regulatory Commission (NRC) approval of proposed Technical Specification (TS) changes for Millstone Power Station Unit 3 for spent fuel pool storage and new fuel storage. In an email dated February 11, 2019, the NRC transmitted a request for additional information (RAI) related to the TS change request.

The attachment to this letter provides DENC's response to the NRC's RAI.

If you have any questions regarding this submittal, please contact Shayan Sinha at (804) 273-4687.

Sincerely,

~~l-Mark D. Sartain Vice President - Nuclear Engineering & Fleet Support COMMONWEAL TH OF VIRGINIA COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mark D. Sartain, who is Vice President - Nuclear Engineering & Fleet Support of Dominion Energy Nuclear Connecticut, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this 21 day of JY} a.n:..h, 2019.

My Commission Expires: 'W\\~r"C,h 31, VJZ:l

~

t; Ai+ke,n Notary Public DIANE E. AITKEN.

NOTARY PUBLIC REG. #7763114 COMMONWEALTH OF VIRGINIA

.i

• MY COMMISSION EXPIRES MARCH 31, 2022'

• Attachments:

Serial No.19-077 Docket No. 50-423 Page 2 of 2

1. Response to Request for Additional Information for Proposed Technical Specification Changes for Spent Fuel Pool Storage and New Fuel Storage

2. Cycle Average Boron Study Related to RAi 4 Response Commitments made in this letter:

1. DENC will implement a disposition process in the relevant plant procedures, which will be followed in the event that fuel is offloaded before the planned end of cycle. This commitment will be closed after the LAR is approved and before the LAR is fully implemented.

2. DENC will implement a disposition process in the relevant plant procedures, which will be followed in the event that fuel assemblies with empty fuel rod lattice locations are identified. This commitment will be closed after the LAR is approved and before the LAR is fully implemented.

cc:

U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd Suite 100 King of Prussia, PA 19406-2713 Richard V. Guzman Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08 C 2 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

ATTACHMENT 1 Serial No.19-077 Docket No. 50-423 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR PROPOSED TECHNICAL SPECIFICATION CHANGE FOR SPENT FUEL STORAGE AND NEW FUEL STORAGE MILLSTONE POWER STATION UNIT 3 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

Serial No.19-077 Docket No: 50-423, Page 1 of 14 By letter dated May 3, 2018, Dominion Energy Nuclear Connecticut, Inc. (DENG) requested Nuclear Regulatory Commission (NRG) approval of proposed Technical Specification (TS) changes for Millstone Power Station Unit 3 (MPS3) for spent fuel storage and new fuel storage.

In an email dated February 11, 2019, the NRG transmitted a request for additional information (RAI) related to the request.

This attachment provides DENC's response to the RAI.

In Attachment 1 of the LAR, the licensee states that there is a 9x9 rack module that was previously approved for installation, but was not installed. The current LAR assumes this 9x9 rack module is installed. With respect to the uninstalled rack, is there any impact to the criticality analysis due to its actual absence; for example, does the missing rack module allow for potentially more reactive locations for misplaced than if the rack was actually installed?

DENC Response The uninstalled module in question is labeled "A5" in MPS3 license amendment request (LAR) Attachment 5 / 6, Figure 4.3. The fuel misplacement locations near rack A5 are:

1) Adjacent to Region 1

2) Adjacent to Region 2

3) Adjacent to Region 3

4) Adjacent to the interface of Regions 1 and 2

5) Adjacent to the interface of Regions 2 and 3 These misplacement locations are the same as those for rack A4 with rack A5 uninstalled. The missing rack does not change the reactivity of a misplacement in the affected section of the spent fuel pool (SFP). The presence or absence of rack A5 does not impact other parts of the criticality analysis because it does not affect the boundary conditions used in the SFP rack models.

RAl2 Section 7.1, "New Fuel Storage Area KENO Model," states the analysis used 8,000 generations, 16,000 neutrons per generation, and 1,000 skipped generations. This is different than what is stated in section 6.1.1, "CSAS5," for how convergence was verified for KENO cases. How was convergence verified for the New Fuel Storage Area (NFSA) KENO Models?

DENC Response Convergence-related KENO input (8,000 generations, 16,000 neutrons per generation, and 1,000 skipped generations) is the same for SFP and NFSA calculations as indicated in Sections 6.1.1 and 7.1.

Section 6.1.1, which is intended to describe computer codes and input applicable to the entire LAR, also contains a description of a

Serial No.19-077 Docket No. 50-423, Page 2 of 14 KENO convergence test.

This description is omitted from Section 7.1, but the same test is used for Section 7 KENO calculations.

RAI 3

With respect to the analysis for the New Fuel Storage Area under optimum moderation, Table 7.10 indicates the cases were run at 32 degrees Fahrenheit (°F) whereas Table 7.5 indicates the optimum moderation situation would be more reactive at higher temperatures. Additionally, Table 7.10 doesn't include the full suite of biases and uncertainties that are included in Table 7.9 for the NFSA fully flooded biases and uncertainties rack-up. Please justify the use of 32°F for the optimum moderation cases and not including the full suite of biases and uncertainties for the optimum moderation situation.

DENC Response The base case description in Table 7.10 of LAR Attachments 5 and 6 mistakenly stated the case was run at 32°F. LAR Attachment 5 / 6, Table 7.10 optimum moderation cases were actually run at 150°F. For completeness, Table 3.1 of this response supplements LAR Attachment 5 / 6, Table 7.8 and contains k-eff results for a full suite of KENO bias and uncertainty cases for the optimum moderation scenario.

These cases

• are performed at the limiting low density moderator density (0.065 cm3) and at the bounding temperature (150°F). Table 3.2, which replaces LAR Attachment 5 / 6, Table 7.10, shows the calculation of total uncertainty, bias and margin to the limit for the optimum density moderator condition. Margin to the k-eff limit (0.0580 dk) is much larger than for the full flooding condition (0.0242 dk).

Serial No.19-077 Docket No. 50-423, Page 3 of 14 Table 3.1 - Bias and Uncertainty Cases for MPS3 NFSR, Optimum Moderation Case Description k-eff a

Ak Nominal., 150 °F (BASE CASE) 0.88241 0.00007 N/A Fuel Stack PTD, Increase 0.88297 0.00007 0.00056 Pellet OD, Increase 0.88273 0.00008 0.00033 Active Fuel Length, Increase 0.88263 0.00007 0.00022 Active Fuel Length, Decrease 0.88241 0.00007 0.00000 Clad ID, Increase 0.88265 0.00008 0.00024 Clad ID, Decrease 0.88213 0.00007

-0.00028 Clad OD, Decrease 0.88282 0.00007 0.00041 Guide Tube ID, Increase 0.88241 0.00007 0.00000 Guide Tube ID, Decrease 0.88243 0.00007 0.00002 Guide Tube OD, Increase 0.88235 0.00008

-0.00006 Guide Tube OD, Decrease 0.88257 0.00007 0.00016 Pin Pitch, Increase 0.88275 0.00007 0.00035 Cell Wall Thickness, Increase 0.87700 0.00007

-0.00540 Cell Wall Thickness, Decrease 0.88807 0.00007 0.00566 Cell Pitch, Increase 0.88406 0.00007 0.00166 Cell Pitch, Decrease 0.88386 0.00007 0.00146 Rack Pitch, Decrease 0.88261 0.00007 0.00020 BORAL Radial Position 0.88242 0.00007 0.00002 Stainless Steel Liner, Decrease 0.89099 0.00008 0.00858 Concrete Thickness, Increase 0.88244 0.00007 0.00004 BORAL Cutouts 0.88425 0.00007 0.00184 Foam Flooded Fuel Building, 0.88504 0.00007 0.00264 0.065 glee

Serial No.19-077 Docket No. 50-423, Page 4 of 14 Table 3.2 - Maximum k-eff for MPS3 NFSR, Optimum Moderation Case Description k-eff C1 Ak Max.Ak Base Case Nominal, 150 °F (Base case) 0.88241 0.00007 N/A N/A Uncertainties Fuel Stack PTO,+

0.88297 0.00007 0.0006 0.0008 Pellet OD,+

0.88273 0.00008 0.0003 0.0005 Active Fuel Length, +

0.88263 0.00007 0.0002 0.0004 Clad ID,+

0.88265 0.00008 0.0002 0.0004 Clad OD, -

0.88282 0.00007 0.0004 0.0006 GTID,-

0.88243 0.00007 0.0000 0.0002 GTOD, -

0.88257 0.00007 0.0002 0.0004 Pin Pitch,+

0.88275 0.00007 0.0003 0.0005 Cell Wall Thickness, -

0.88807 0.00007 0.0057 0.0059 Cell Pitch,+

0.88406 0.00007 0.0017 0.0019 Rack Pitch, -

0.88261 0.00007 0.0002 0.0004 BORAL radial position 0.88242 0.00007 0.0000 0.0002 Concrete Thickness, +

0.88244 0.00007 0.0000 0.0002 Stainless Steel Liner Thickness, -

0.89099 0.00008 0.0086 0.0088 KENO Case Uncertainty N/A N/A N/A 0.0002 Code Benchmarking Unc.

N/A N/A N/A 0.0078 RSS of Uncertainties 0.0134 Biases Foam flooded building 0.88504 0.00007 0.0026 0.0028 BORAL cutout 0.88425 0.00007 0.0018 0.0020 Code Temperature Bias N/A N/A N/A 0.0008 Code Benchmarking Bias N/A NIA N/A 0.0105 Sum of Biases 0.0162 Summary Base Case k-eff 0.8824 Total Bias and Uncertainty 0.0296 NRC Administrative Margin 0.01 Maximum k-eff 0.9220 1 OCFR50.68 Limit 0.98 DOMINION Margin 0.0580

RAl4 Serial No.19-077 Docket No. 50-423, Page 5 of 14 Section 8.3, "Bounding Depletion Boron," indicates the depletion analysis used a cycle average soluble boron of 1050 ppm. The reference for using a cycle average soluble boron is J. C. Wagner, "Impact of Soluble Boron Modeling for PWR Burnup Credit Criticality Safety Analyses," Trans. Am. Nucl. Soc., 89, pp. 120 (2003). That reference indicates that using a cycle average soluble boron could be non-conservative for fuel discharged to the SFP following a mid-cycle shutdown or short cycle. Describe how the analysis accounts for this potential.

DENC Response In support of this response, DENC performed a study using CASM0-5 and KENO V.a that replicates the Wagner paper (Reference 1) and extends the analysis to include typical MPS3 cycle characteristics. The study is included in Attachment 2 of this letter.

The DENC study shows that the greatest potential effect is for third cycle fuel and that most of the potential non-conservatism is based on comparing the more realistic boron letdown depletion of a shortened cycle to a fixed boron depletion in which the boron is held equal to the full cycle average boron.

The Wagner paper does not make use of the actual lifetime average boron in the constant boron depletion when calculating the k-ratio.

Accounting for the actual average depletion boron reduces the non-conservatism shown in the Wagner paper by about 75%. For a typical MPS3 cycle, depletion with actual lifetime average boron for the constant boron depletion accounts for all but 44 pcm maximum non-conservatism. This value encompasses one cycle, two cycle, and three cycle fuel assemblies. Details regarding calculation of this maximum reactivity non-conservatism are shown in Attachment 2 of this letter.

The 44 pcm maximum boron history non-conservatism does not need to be accounted for directly because the maximum value is small relative to conservatism in the LAR. In particular, LAR burnup credit depletions use mutually exclusive maximum depletion temperatures and 50% reduced power during the last 40 days of depletion (LAR / 6, Section 5.2.4 and Section 8.10). The reduced power assumption allows for the possibility of a very long power coastdown ne~r end of core life, which is inconsistent with operations before a mid-cycle shutdown. Therefore, it is not realistic to apply a bias to cover both the end of cycle power coastdown and the boron history non-conservatism which would occur after a middle of cycle shutdown. The effect of this non-physical hybrid power coastdown depletion as compared to a bounding high power-only depletion is on the order of 0.003 dk (LAR Attachment 5 / 6, Table 8.11), which is about seven times the amount needed to offset the maximum boron history non-conservatism. Relative to the LAR burnup credit depletions, power reduction for less than 40 days or of a lesser degree than 50% prior to a mid-cycle offload would result in lower depletion temperatures and higher Pm-149. This would reduce SFP fuel reactivity relative to the LAR analysis and tend to offset the already small potential boron history non-conservatism.

Serial No.19-077 Docket No. 50-423, Page 6 of 14 The MPS3 LAR uses a cycle average boron (1050 ppm) that bounds the fuel boron depletion history for all historical MPS3 fuel assemblies. For new cycle designs, the design process includes a step to verify that the LAR cycle average boron will remain bounding if the cycle is not unexpectedly shortened.

For a cycle that is unexpectedly shortened, a check will be performed prior to offloading fuel to determine if the actual cycle average boron is less than the limit. If the boron limit is exceeded, a disposition of affected fuel assemblies will be performed that incorporates the actual lifetime average boron.

This is consistent with guidance in Nuclear Energy Institute (NEI) Guidance.Document 12-16, Section 4.2.1 (Reference 2):

"The licensee will confirm the actual cycle-average soluble boron for the purposes of confirming the individual cycles meet the inputs of the approved analysis.,,

NEI 12-16 (Reference 2) also addresses the issue of mid-cycle offload:

"A licensee would evaluate a mid-cycle offload in accordance with the licensee's corrective action program and current NRC guidance for identifying and resolving pQtential nonconseNatisms or unanalyzed conditions in a design basis analysis. If an issue is identified, the licensee would make an initial operability determination, and subsequently evaluate in accordance with 50.59 to determine whether NRC approval is required.

As a default, any fuel assembly could be conseNatively treated as a fresh fuel assembly with no burnable absorbers.,,

DENC will implement the following disposition process that is similar to, but somewhat less limiting than the NEI 12-16 (Reference 2) guidance. In the event that end of cycle average boron is greater than 1050 ppm, DENC will take the following steps:

1) Prior to fuel offload, determine the cumulative burnup averaged boron for fuel in the affected cycle. Identify affected fuel assemblies with average boron history greater than 1050 ppm.

2) Document any affected fuel assemblies using the corrective action system.

3) As a temporary resolution to* allow offload to proceed, disregard the fuel burnup acquired by affected fuel assemblies in the affected cycle. This is less restrictive than the NEI guidance but fully bounds a mid-cycle offload. Fuel assemblies may only be moved to locations for which they are qualified with the administratively reduced fuel burnup.

4) Evaluate in accordance with 10 CFR 50.59 whether affected fuel assemblies are bounded by the bounding burnup credit analysis in the LAR. This step may involve performing burnup credit calculations using the methods described in the LAR to credit actual fuel assembly design and/or depletion history that is less bounding than the bounding input values used in the LAR analysis.

The evaluation may include performing the LAR burnup credit calculation with known fuel design and depletion history inputs rather than assumed bounding values such as:

a. Actual average depletion boron

b. Actual burnable absorber loading

c. Actual depletion power and temperature

d. Actual fuel assembly burnup Serial No.19-077 Docket No. 50-423, Page 7 of 14

5) If the evaluation identifies sufficient offsetting depletion parameters such that the affected fuel is bounded by the LAR analysis, document the analysis and close the corrective action issue.

6) If the evaluation does not identify sufficient offsetting depletion parameters, then determine the amount of non-conservatism and use MPS3 LAR reserved Dominion margin to disposition affected fuel.

7) If insufficient MPS3 LAR reserved Dominion margin exists, then determine a SFP storage burnup penalty sufficient to offset the non-conservatism using the LAR burnup credit methodology.

Given that DENC's study in Attachment 2 determined the maximum estimated mid-cycle offload reactivity effect to be much less than the MPS3 reserved Dominion margin, and given that many of the assumed simultaneously bounding LAR depletion inputs are highly conservative relative to actual MPS3 fuel designs and depletion history, it is unlikely that a burnup penalty would be required.

However, that step is included for completeness.

References:

1. J. C. Wagner, "Impact of Soluble Boron Modeling for PWR Burnup Credit Criticality Safety Analyses," Trans. Am. Nucl. Soc., 89, pp. 120 (2003).

2. Nuclear Energy Institute (NEI) Guidance Document 12-16, Revision 3, ADAMS Accession No. ML180888400, "Guidance for Performing Criticality Analysis of Fuel Storage at Light-Water Reactor Power Plants," March 2018.

RAIS The Maximum Wet Annular Burnable Absorbers (WABA) results in Table 8.9 differ from those in Table 8. 7. Explain the difference.

DENC Response LAR Attachment 5 / 6, Table 8.7 results are for sensitivity cases using a single axial node (node 16) that is representative of the full assembly. Axial detail is not needed to determine which Integral Fuel Burnable Absorber (IFBA) and WABA combinations are equivalent to maximum strength WABA because those burnable absorbers extend nearly the entire axial length of the fuel. Results in LAR Attachment 5 / 6, Table 8.9 are for the KENO model with 18 axial nodes (or 19 for partial node control rod insertion).

The axial detail in LAR Attachment 5 / 6, Table 8.9 is needed to determine the reactivity effect of control rod insertion history.

Serial No.19-077 Docket No. 50-423, Page 8 of 14 During storage, a fuel assembly may occupy various positons [sic] within the storage cell and some may be more reactive than assuming all fuel assemblies are centered in the storage cell. Section 9. 6.4, Asymmetric Fuel Placement," addresses this for Region

2. However, for Region 2, a 2x2 array was used. In a 2x2 array, while the four assemblies in the array can be moved closer together, they are a/so being moved further away from adjacent 2x2 arrays. This results in potentially offsetting reactivity effects in the model. Justify the use of a 2x2 array for the Region 2 asymmetric analysis.

DENC Response A Region 2 6x6 KENO model was used to calculate the effect of horizontal burnup tilt and is described in LAR Attachment 5 / 6, Section 9.6.6. To verify that centering fuel in each storage cell maximizes Region 2 k-eff, the 6x6 KENO horizontal tilt base case (2.6 wt% 10 GWd/MTU) is modified to asymmetrically place 16 fuel assemblies in the center 4x4 of the 6x6 model. Fuel is placed in each of the 4x4 storage cells such that they are as close to the center of the 6x6 array as possible.

Figure 6.1 shows the fuel orientation.

The symmetric base case k-eff is 0.96816 +/- 0.00006.

The asymmetric case k-eff is 0.96727 +/- 0.00006. The 6x6 model confirms the 2x2 results in LAR Attachment 5 / 6, Section 9.6.4 that indicate centered fuel placement maximizes k-eff.

Serial No.19-077 Docket No. 50-423, Page 9 of 14 Figure 6.1 - Asymmetric Fuel Placement in the Region 2 6x6 KENO Model

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Section 9. 6. 11, "Region 2 Control Rod Credit," states: "Removal of the control rod must be performed with the assembly in a Region in which it qualifies for storage without the control rod." It is also a requirement that the insertion of the control rod must be performed with the assembly in a Region in which it qualifies for storage without the control rod. Explain how these requirements are controlled.

DENC Response The process used to administratively control storage of fuel assemblies requiring control rod credit is the same process used to control all other spent fuel pool storage requirements, including fuel assembly enrichment limits, burnup credit, and decay time.

Proposed TS 3.9.13 in LAR Attachment 2 includes a general TS note for the surveillance requirements that states, in part:

Serial No.19-077 Docket No. 50-423, Page 10 of 14 "Regarding fuel assemblies that contain a Rod Cluster Control Assembly for storage in Region 2 - if the enrichment and burnup of a given assembly is not in the "Acceptable" domain of Figure 3.9-2 (e.g., the assembly requires a Rod Cluster Control Assembly to be stored in Region 2), then the assembly must be located in an acceptable Region 1 storage location before its Rod Cluster Control Assembly can be inserted or removed."

Following NRC approval of the MPS3 LAR, station and Dominion Energy fleet procedures will be revised to incorporate associated requirements including those that ensure fuel is stored in a region where it is qualified without a control rod prior to installing the control rod and prior to removing the control rod. Modification or removal of this TS note would require a LAR in accordance with 10 CFR 50.90.

RAIS Section 11. 1, "Fuel Handling," states that procedures will preclude fuel outside the storage racks from being closer than 12 inches. Provide the following information:

a.

How procedures will prevent operators from moving an assembly within 12 inches of any other fuel.

b.

Whether there are any physical barriers that prevent moving an assembly within 12 inches of other fuel.

c.

How fuel handling operators will know the distance between a fuel assembly being moved and any other fuel.

DENC Response RAI Sa Response:

A 12-inch fuel assembly separation requirement is included in applicable MPS3 engineering and operating procedures governing receipt and handling of new and spent fuel assemblies to support a 10 CFR 50.68 (b) related MPS3 Final Safety Analysis Report (FSAR) commitment. In addition, fuel handling procedures limit the type and number of situations in which two fuel assemblies outside the storage racks could be closer than 12 inches apart. Only one fuel assembly at a time may be moved in the MPS3 SFP.

Movement of fuel assemblies requires a prepared and independently reviewed fuel handling report, and procedures provide guidance for independent verification that fuel and insert movements are performed in accordance with the fuel handling report.

Because of the controlled process used to develop and confirm fuel movement, particularly the restriction of moving only one fuel assembly at a time and the requirement for fuel to be formally qualified for movement to a particular storage location, there are only a few potential situations in which more than one fuel assembly

Serial No.19-077 Docket No. 50-423, Page 11 of 14 could be outside of a normal storage location at the same time. During the 10 CFR 50.68 (b) related MPS3 FSAR update, a review of MPS3 fuel handling procedures identified some specific fuel handling scenarios requiring procedural controls to ensure adequate fuel separation:

1) The New Fuel Elevator (NFE) and the transfer container are both located in the transfer canal.

If a fuel assembly is in the NFE or in the transfer container, it is possible for the spent fuel hoist to bring a fuel assembly next to the fuel assembly in the NFE or the transfer container.

2) A fuel assembly could be placed adjacent to a fuel storage rack. Such a circumstance is not expected to occur because open areas between fuel racks are not normally considered approved storage locations. However, this scenario is considered possible.

For example, a future fuel inspection process (special camera, etc.) could hypothetically benefit from use of open pool space.

Because of these possible scenarios, plant procedures require that a fuel assembly being lowered outside of an approved storage location be at least 12 inches away from the nearest fuel assembly.

RAI Sb Response:

In general, there are no physical barriers in the SFP or in the transfer canal that would prevent moving a fuel assembly within 12 inches of another fuel assembly.

The NFE carriage assembly and the fuel transfer structure would provide a small amount of separation in the transfer canal. As noted in the RAI 8a response, lack of physical barriers is recognized in the establishment of administrative controls governing fuel handling and movement.

RAI Sc Response:

The fuel handling operators can use the width of the fuel assembly (approximately 8 inches square) to visually estimate the distance between a fuel assembly being moved and any other fuel.

This method is reasonable because the requirement for 12 inches of separation is very conservative.

LAR Attachment 5 / 6, Figure 11.1 show that at 4 inches separation (10 cm) the k-eff for two fresh un-poisoned 5.0 wt% U-235 fuel assemblies in unborated water is 0.968.

Base case k-effs for acceptable fresh fuel storage in Regions 1, 2, and 3 are 0.9675, 0.9657, and 0.9691, respectively (LAR Attachment 5 / 6, Tables 9.6, 9.20. and 9.28).

The 4-inch assembly separation k-eff (0.968) is acceptable because it is similar to k-eff for rack storage base cases and because there are fewer bias and uncertainty terms for two bare fuel assemblies than for fuel in a storage rack. Visual estimation of 12-inch separation distance is appropriate because there is adequate conservatism (approximately a factor of three) incorporated in the separation requirement.

RAl9 Serial No.19-077 Docket No. 50-423, Page 12 of 14 Section 11. 3. 2, "Reconstituted Fuel," addresses the process of reconstituting fuel and the storage of reconstituted fuel. Provide the following information:

a.

Region 1 wasn't explicitly modeled. Confirm that the requirement for storage cells that are face adjacent to the fuel assembly being reconstituted will also be applied to Region 1.

b.

The analysis did not address the number of fuel rod lattice locations that can be empty during the reconstitution process. Specify the number of fuel rod lattice locations that can be empty during the reconstitution process.

c.

The analysis addresses one fuel assembly with two empty fuel rod lattice locations. How would the licensee address other fuel assemblies with empty fuel rod lattice locations?

DENC Response RAI 9a Response:

The requirement to maintain empty storage cells in the four face-adjacent locations of a fuel assembly being reconstituted applies to storage Regions 1, 2, and 3. Region 1 was not addressed directly because it is less reactive than and bounded by the analysis for Regions 2 and 3 (e.g. LAR Attachment 5 I 6, Section 11.4 fresh fuel enrichment with 4 out of 4 storage).

RAI 9b Response:

With the reconstitution fuel assembly isolated, there is no limit on the number of empty fuel lattice locations. Confirmation is provided in Table 9.1. The Region 2 reconstitution model (LAR Attachment 5 / 6, Table 11.2) is modified by replacing the normal reconstitution fuel assembly near the center of the model with uniform pitch fuel lattices of varying number of fuel rods per side (maintaining the normal fuel assembly envelope) and, for some cases, varying rod pitch with the same reduced number of fuel rods.

Varying the number of fuel rods and rod pitch will iteratively search for the optimum fuel to moderator ratio. KENO cases have no soluble boron and are run with moderator temperature set to 32°F.

Figure 9.1 shows the configuration of the 100 fuel rod reconstitution model. Region 2 results were confirmed to also be valid for Region 3. As stated in RAI response 9a, Region 1 is bounded by Regions 2 and 3.

Table 9.1 and Figure 9.2 show that the reconstitution cases have k-eff well below the nominal full rack base case k-eff, and that the effects of empty fuel rod locations in the reconstitution assembly are negligible when the reconstitution assembly is neutronically isolated (four face adjacent empty cells). Therefore, there is no limit on the number of empty fuel lattice locations during reconstitution in Regions 1, 2, or 3.

Case Base Pitch1 Pitch2 Pitch3 Pitch3A Pitch 38 Pitch4 Pitch5 Pitch6 Pitch?

Pitch8 Serial No.19-077 Docket No. 50-423, Page 13 of 14 Figure 9.1 - KENO Region 2 6x6 Model Table 9.1 - KENO 6x6 Model Region 2 Reconstitution Cases Fuel rods Fuel Pitch k-eff Uncert.

KENO Case per rods (cm) side 17 264 1.260 0.96422 0.00006 MPS3 Reg2 recon base 17 289 1.260 0.94663 0.00007 MPS3 ReQ2 recon isolface oitch1 16 256 1.339 0.94634 0.00007 MPS3 Reg2 recon isolface oitch2 15 225 1.428 0.94646 0.00006 MPS3 Req2 recon isolface oitch3 15 225 1.339 0.94651 0.00007 MPS3 ReQ2 recon isolface oitch3A 15 225 1.260 0.94654 0.00007 MPS3 Reg2 recon isolface oitch3B 14 196 1.530 0.94657 0.00006 MPS3 ReQ2 recon isolface oitch4 13 169 1.648 0.94657 0.00007 MPS3 Reg2 recon isolface oitch5 12 144 1.785 0.94671 0.00007 MPS3 Req2 recon isolface oitch6 11 121 1.947 0.94653 0.00007 MPS3 Reg2 recon isolface oitch7 10 100 2.142 0.94649 0.00007 MPS3 ReQ2 recon isolface oitch8

Serial No.19-077 Docket No. 50-423, Page 14 of 14 Figure 9.2 - KENO 6x6 Model Region 2 Reconstitution Cases 0.966 0.964 0.962 0.960 0.958

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! 0.954 0.952 0.950 0.948 0.946 0.944 RAI 9c Response:

10 11 Region 2 Reconstitution Cases

• Reconstitution Cases

-Base Case i*

12 13 14 15 16 Number of Fuel Rods per Side 17 Analysis of the effect of empty fuel rod locations will be performed on an assembly-specific basis in the same manner as for assembly MR71 (LAR Attachment 5 / 6, Section 11.3.2). Fuel assemblies in the KENO rack model are modeled with removed fuel rods replaced by water and the resulting k-eff is compared to an analogous base case for an assembly with no removed rods.

If the k-eff of the intact assembly is bounding, the assembly may be stored as a normal assembly.

If k-eff for the fuel assembly with missing fuel rods is higher than the intact assembly, then the excess reactivity will be dispositioned using the LAR methodology to identify a source of k-eff margin (similar to RAI 4). Some potential sources of margin include:

1) Retained Dominion Energy margin

2) Depletion with actual fuel characteristics rather than assumed bounding input values

a. Burnable absorber content

b. Actual average soluble boron

c. Actual maximum assembly power and temperature history

3) Assembly burnup in excess of Region storage requirement If there is still insufficient margin after considering these sources, a burnup penalty can be assessed.

ATTACHMENT 2 Serial No.19-077 Docket No. 50-423 CYCLE AVERAGE BORON STUDY RELATED TO RAI 4 RESPONSE MILLSTONE POWER STATION UNIT 3 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

Serial No.19-077 Docket No. 50-423, Page 1 of 10 In order to better understand the source of non-conservatism, the calculations described in the J. C. Wagner paper (Reference 1 of Attachment 1) are replicated using CASM0-

5. CASM0-5 is preferred for this RAI response due to the number of depletion cases required and the amount of analysis time involved when using TRITON. CASM0-5 was shown to produce depletion reactivity results very similar to TRITON in LAR Attachment 5 / 6, Section 8.14.

Fuel design and depletion parameters are listed in Table 4.1 (mostly taken from the Wagner paper). Figure 4.1 shows the fuel depletion boron history, which is the same as that used in the Wagner paper for the 1000 ppm cycle average boron scenario.

There are three cycles of fuel depletion, each with the same boron history. Fuel is depleted at a constant power with burnup accumulation of 15 GWd/MTU each cycle.

As shown in Figure 4.1, an early cycle shutdown has the potential to affect the fuel assembly lifetime average boron the most in the first cycle of depletion and the least in the third cycle of depletion.

Table 4.1 - Fuel Design and Depletion Parameters Parameter Value Fuel Type 17x17 Burnable Absorber None Enrichment 4.0 wt. % U-235 Fuel Temperature 1100 K Moderator 610 K Temperature Power 60 W/g U To replicate the Wagner results, two depletions are performed. The first uses the Figure 4.1 letdown curve soluble boron (dashed line) and the second uses constant 1000 ppm soluble boron. The constant boron value is equal to the burn up-weighted cycle average boron for a completed cycle.

Figure 4.1 also shows the fuel lifetime average boron (cumulative burnup weighted soluble boron). Calculation of the lifetime average boron is shown in Table 4.2. Table 4.2 also contains CASM0-5 cold, no boron, no xenon k-infinity vs. burnup values (conditions similar to spent fuel pool (SFP) storage) and a "k-ratio" that is used to represent the reactivity difference of fuel depleted with constant boron relative to fuel depleted with letdown boron.

The CASMO case is written so that it depletes the fuel assembly to 45 GWd/MTU.

Then at each burnup step, a CASMO restart case is run that resets the temperatures to 273 K, sets the soluble boron to O, and sets the Xe-135 concentration to O in order to approximate fuel storage conditions. As in the Wagner paper, the k-ratio is calculated at each burnup as follows:

k-ratio = k-inf. (Constant boron) / k-inf. (Letdown boron)

Figure 4.2 shows the k-ratio for the 1000 ppm boron (average) 15 GWd/MTU cycle depletions.

The results show the same k-ratio pattern versus assembly burnup and

Serial No.19-077 Docket No. 50-423, Page 2 of 10 similar magnitude as Figure 2 of the Wagner paper. A k-ratio less than 1 indicates that the constant boron depletion is non-conservative.

Figure 4.1 - Soluble Boron Depletion History (1000 ppm cycle average)

Hypothetical Multi-Cycle Depletion Boron 2000 1800 1600 1400

[ 1200 3

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, 800 0

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Soluble Boron vs. Burnup ~

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10 15 20 25 30 35 40 45 Cumulative Fuel Burnup (GWd/MTU)

Serial No.19-077 Docket No. 50-423, Page 3 of 10 Table 4.2 - Soluble Boron versus Burnup for Wagner 1000 ppm Cycle Average Boron Depletion Step Lifetime Fixed Step Burnup Boron average Average boron Letdown Number (GWd/MTU)

(ppm) boron boron k-inf.

k-inf.

k-ratio 0

0 2000 2000 2000 1

1 1867 1933 1933 1.44281 1.44257 1.0002 2

2 1733 1800 1867 1.43125 1.43098 1.0002 3

3 1600 1667 1800 1.4198 1.41959 1.0001 4

4 1467 1533 1733 1.40812 1.40799 1.0001 5

5 1333 1400 1667 1.39648 1.39643 1.0000 6

6 1200 1267 1600 1.38503 1.38509 1.0000 7

7 1067 1133 1533 1.37387 1.37401 0.9999 8

8 933 1000 1467 1.363 1.36323 0.9998 9

9 800 867 1400 1.35245 1.35273 0.9998 10 10 667 733 1333 1.34219 1.34251 0.9998 11 11 533 600 1267 1.33221 1.33252 0.9998 12 12 400 467 1200 1.32248 1.32274 0.9998 13 13 267 333 1133 1.31299 1.31315 0.9999 14 14 133 200 1067 1.30371 1.30372 1.0000 15 15 0

67 1000 1.29463 1.29443 1.0002 16 15.01 2000 2000 1001 1.0002 17 16 1867 1933 1058 1.28572 1.28471 1.0008 18 17 1733 1800 1102 1.27698 1.27634 1.0005 19 18 1600 1667 1133 1.2684 1.26822 1.0001 20 19 1467 1533 1154 1.25996 1.26019 0.9998 21 20 1333 1400 1167 1.25164 1.25221 0.9995 22 21 1200 1267 1171 1.24346 1.24427 0.9993 23 22 1067 1133 1170 1.23538 1.23637 0.9992 24 23 933 1000 1162 1.22742 1.2285 0.9991 25 24 800 867 1150 1.21956 1.22066 0.9991 26 25 667 733 1133 1.21181 1.21284 0.9992 27 26 533 600 1113 1.20415 1.20504 0.9993 28 27 400 467 1089 1.19658 1.19725 0.9994 29 28 267 333 1062 1.18912 1.18947 0.9997 30 29 133 200 1032 1.18174 1.18168 1.0001 31 30 0

67 1000 1.17445 1.1739 1.0005 32 30.01 2000 2000 1000 1.0005 33 31 1867 1933 1030 1.16725 1.16582 1.0012 34 32 1733 1800 1054 1.16014 1.15928 1.0007 35 33 1600 1667 1073 1.15312 1.15295 1.0001 36 34 1467 1533 1086 1.14618 1.14661 0.9996 37 35 1333 1400 1095 1.13934 1.14023 0.9992 38 36 1200 1267 1100 1.13258 1.13381 0.9989 39 37 1067 1133 1101 1.12591 1.12736 0.9987 40 38 933 1000 1098 1.11933 1.12088 0.9986 41 39 800 867 1092 1.11284 1.11436 0.9986 42 40 667 733 1083 1.10644 1.10782 0.9988 43 41 533 600 1072 1.10014 1.10125 0.9990 44 42 400 467 1057 1.09393 1.09464 0.9994 45 43 267 333 1040 1.08781 1.08801 0.9998 46 44 133 200 1021 1.08179 1.08135 1.0004 47 45 0

67 1000 1.07586 1.07466 1.0011

Serial No.19-077 Docket No. 50-423, Page 4 of 10 Figure 4.2-1000 ppm Depletion k-ratio 1000 ppm Boron Depletion k-ratio c 1.0005 +-----+----+---+t----+----+---+---+---+-----+----++------i

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0

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C ! 1.0000 +-----P-

--+----#-+-----'.......... ---+----l-+----1>---4---+---4---1-------1 Ill C

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-¥ 0.9995 +-----+----+---+------1'l-----+---+--+----1-t-----+---+-+------i 0

s 10 15 20 25 30 35 40 45 so Fuel Assembly Burnup (GWd/MTU}

In Figure 4.2, the lowest k-ratio occurs in the middle of the third depletion cycle even though the maximum difference between the lifetime average boron and 1000 ppm occurs during the first depletion cycle. This result confirms that the sensitivity to greater than average boron during depletion is higher at higher fuel burnup.

Replication of the Wagner paper results confirms that the identified potential non-conservatism (low k-ratio) is based on comparing the boron letdown depletion of a shortened cycle to a fixed boron depletion in which the boron is held equal to the full cycle average boron.

This method does not make use of the actual lifetime average boron (Fig. 4.1 solid line) in the constant boron depletion when calculating the k-ratio.

The MPS3 LAR uses a cycle average boron (1050 ppm) that bounds the fuel boron depletion history for all historical MPS3 fuel assemblies. If the boron limit is exceeded, a disposition of affected fuel assemblies will be performed that incorporates the actual lifetime average boron. This is consistent with guidance in NEI 12-16, Section 4.2.1:

Serial No.19-077 Docket No. 50-423, Page 5 of 10 "The licensee will confirm the actual cycle-average soluble boron for the purposes of confirming the individual cycles meet the inputs of the approved analysis."

In order to determine if depletion with the actual average boron fully accounts for the Wagner paper non-conservatism, k-ratios were re-calculated for the most limiting burnup of the first, second, and third cycles of Figure 4.2 after re-depleting using a constant boron equal to the actual lifetime average boron.

Figure 4.3 shows the k-ratios after accounting for the increase in cycle average boron for the 10, 24, and 38 GWd/MTU burnup points added to the Figure 4.2 plot. Each added k-ratio is calculated in the same manner as the values in Figure 4.2, except that for the 38 GWd/MTU burnup an additional case with 5 years of decay is provided to ensure that decay time does not change the conclusions of this study.

K-inf. cases used to calculate the k-ratio values are shown in Table 4.3.

Figure 4.3-1000 ppm CASM0-5 Depletion k-ratio with Correct Average Boron 1000 ppm Boron Depletion k-ratio Effect of Correct Average boron 1.0015 -,------,-----...---,-----,-----,----.----~---.-----,-----,

1.0010 +-----+----+---+-----+---+---I-I-\\---+----+--- --~

11.0005 +------+----+---tt--+-----+---t----.1---1---+----+----t--i---,

0 "D

....... c f 1.0000 _,_ _____

___,.--+---+---l-l----+--+----+--1--1----<

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0.:

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0.9990

-1000 ppm Avg Boron O 1098 ppm avg boron

• 1150 ppm Avg Boron A 1333 ppm Avg Boron

• 1098 ppm 5 Yr Decay 0.9985 +------+----+---+------+---t---1----+----+--------!---,

0 5

10 15 20 25 30 35 40 45 50 Fuel Assembly Burnup (GWd/MTU)

Serial No.19-077 Docket No. 50-423, Page 6 of 1 O Figure 4.3 shows that most (>80% at 38 GWd/MTU) of the Wagner non-conservatism is eliminated if the actual lifetime average boron is accounted for. The remainder is small.

K-inf. values for the CASM0-5 cases are shown in Table 4.3.

Table 4.3-Wagner Depletion History 10, 24, and 38 GWd/MTU CASM0-5 Results Avg Depletion Boron boron Decay Non-conservatism Method (ppm)

Burnup Time k-inf.

k-ratio (pcm)

Constant 1000 38 0

1.11933 0.99862 124 Letdown 1098 38 0

1.12088 N/A NIA Constant 1098 38 0

1.12059 0.99974 23 Letdown 1333 10 0

1.34251 N/A N/A Constant 1333 10 0

1.34246 0.99996 3

Letdown 1150 24 0

1.22066 N/A N/A Constant 1150 24 0

1.22045 0.99983 14 Letdown 1098 38 5

1.0908 N/A N/A Constant 1098 38 5

1.09058 0.99980 18 For MPS3, boron letdown curves are not linear, and cycle length is roughly 20 GWd/MTU.

To address typical MPS3 boron history, the calculations performed for Figures 4.2 and 4.3 are replicated with CASM0-5 using the MPS3 Cycle 19 predicted boron letdown and a shortened cycle length of 20 GWd/MTU. Figure 4.4 and Table 4.4 show the boron versus burnup data and calculations.

Table 4.4 also contains the CASM0-5 cold restart no boron k-infinity vs burnup values and the k-ratio for the boron letdown and constant boron (914 ppm) depletions.

Figure 4.5 shows the MPS3 k-ratio from Table 4.4 along with the k-ratio for the 50 GWd/MTU point after depletion with constant 991 ppm boron (the actual lifetime average boron at that burnup).

Accounting for the actual average depletion boron reduces the non-conservatism by about 75%. Table 4.5 summarizes the k-ratio results for the 50 GWd/MTU point. Based on the CASM0-5 results, using the actual lifetime average boron for the constant boron depletion leaves only 43 pcm non-conservatism to be addressed.

1600 1400 1200 E 1000

a..e C:

0... 800 0

r:11 Qj j5 0

600 Ill 400 200 0

0 Figure 4.4 - MPS3 Depletion Boron Serial No.19-077 Docket No. 50-423, Page 7 of 10 Millstone Unit 3 Typical Multi-Cycle Depletion Boron 914 ppm Cycle Average Boron

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Soluble Boron vs. Burnup \\

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Serial No.19-077 Docket No. 50-423, Page 8 of 10 Table 4.4 - Soluble Boron versus Burnup for Typical MPS3 Cycle Depl Step Cycle Fixed Step average Fixed Average boron Letdown Number Burnup Boron boron boron boron k-inf.

k-inf.

k-ratio 0

0 1373 1373 914 1373 1

1 1382 1378 914 1378 1.44283 1.44271 1.0001 2

2 1416 1399 914 1388 1.43128 1.43113 1.0001 3

3 1425 1421 914 1399 1.41983 1.41968 1.0001 4

4 1406 1416 914 1403 1.40814 1.40802 1.0001 5

5 1367 1387 914 1400 1.39649 1.39642 1.0001 6

6 1312 1340 914 1390 1.38504 1.38504 1.0000 7

7 1246 1279 914 1374 1.37385 1.37394 0.9999 8

8 1171 1209 914 1353 1.36297 1.36316 0.9999 9

9 1089 1130 914 1328 1.3524 1.35268 0.9998 10 10 1003 1046 914 1300 1.34212 1.34248 0.9997 11 12 820 912 914 1235 1.32236 1.32284 0.9996 12 14 627 724 914 1162 1.30354 1.30403 0.9996 13 16 432 530 914 1083 1.28549 1.28586 0.9997 14 18 238 335 914 1000 1.2681 1.26817 0.9999 15 20 47 143 914 914 1.25128 1.25085 1.0003 16 20.001 1373 1373 914 914 1.0003 17 21 1382 1378 914 936 1.24305 1.24199 1.0009 18 22 1416 1399 914 957 1.23494 1.2341 1.0007 19 23 1425 1421 914 978 1.22694 1.22643 1.0004 20 24 1406 1416 914 996 1.21905 1.21889 1.0001 21 25 1367 1387 914 1011 1.21125 1.21144 0.9998 22 26 1312 1340 914 1024 1.20355 1.20406 0.9996 23 27 1246 1279 914 1033 1.19595 1.19675 0.9993 24 28 1171 1209 914 1040 1.18844 1.18948 0.9991 25 29 1089 1130 914 1043 1.18102 1.18225 0.9990 26 30 1003 1046 914 1043 1.17369 1.17506 0.9988 27 32 820 912 914 1035 1.15929 1.16074 0.9988 28 34 627 724 914 1016 1.14525 1.14651 0.9989 29 36 432 530 914 989 1.13155 1.13232 0.9993 30 38 238 335 914 955 1.11821 1.11818 1.0000 31 40 47 143 914 914 1.10523 1.10406 1.0011 37 40.001 1373 1373 914 914 1.0011 38 41 1382 1378 914 926 1.09888 1.09701 1.0017 39 42 1416 1399 914 937 1.09262 1.09118 1.0013 40 43 1425 1421 914 948 1.08646 1.08557 1.0008 41 44 1406 1416 914 959 1.08039 1.08009 1.0003 42 45 1367 1387 914 968 1.07442 1.07467 0.9998 43 46 1312 1340 914 976 1.06854 1.06929 0.9993 44 47 1246 1279 914 983 1.06277 1.06395 0.9989 45 48 1171 1209 914 987 1.05709 1.05863 0.9985 46 49 1089 1130 914 990 1.05152 1.05331 0.9983 47 50 1003 1046 914 991 1.04604 1.048 0.9981 48 52 820 912 914 988 1.0354 1.03738 0.9981 49 54 627 724 914 979 1.02515 1.02674 0.9985 50 56 432 530 914 963 1.01532 1.01608 0.9993 51 58 238 335 914 941 1.00591 1.0054 1.0005 52 60 47 143 914 914 0.99693 0.99472 1.0022

1.0025 1.0020 1.0015 1.0010 1.0005 1.0000.--.......

0.9995 0.9990 0.9985 Serial No.19-077 Docket No. 50-423, Page 9 of 10 Figure 4.5 - MPS3 CASM0-5 Depletion k-ratio MP3 Depletion k-ratio A

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• 991 ppm Avg Boron 0.9975 I

0 10 20 30 40 so 60 70 Fuel Assembly Burnup (GWd/MTU)

Table 4.5 - MPS3 Depletion History 50 GWd/MTU CASM0-5 Results Avg Depletion Boron boron Decay Non-conservatism Method (oom)

Burnup Time k-inf.

k-ratio (pcm)

Constant 914 50 0

1.04604 N/A 179 Letdown 991 50 0

1.048 0.99813 N/A Constant 991 50 0

1.04753 0.99955 43 Finally, to verify that the CASM0-5 results adequately represent the amount of boron history non-conservatism, fuel compositions from the Table 4.5 CASM0-5 cases were used in the MPS3 KENO Region 3 SFP rack model at 150°F with O ppm boron. Table 4.6 shows the nuclides used in the KENO model. Results in Table 4.7 show that the

Serial No.19-077 Docket No. 50-423, Page 10 of 10 best estimate non-conservatism is 37 pcm (44 pcm including 2 sigma uncertainty). This calculation confirms that the maximum remaining boron history non-conservatism is also small under SFP storage conditions.

Table 4.6 - CASM0-5 Nuclides Included in the Depletion History KENO Model Ag-109 Eu-153 Np-239 Sm-150 Ag-110 Eu-154 Pm-147 Sm-151 Ag-111 Eu-155 Pm-148 Sm-152 Am-241 Eu-156 Pm-148 Sn-126 Am-242 Gd-155 Pm-149 Sr-89 Am-242 Gd-157 Pr-143 Sr-90 Am-243 1-127 Pu-237 Tc-99 Am-244 1-129 Pu-238 Te-127 Ba-138 1-131 Pu-239 Te-129 Ba-140 Kr-83 Pu-240 U-234 Ce-141 Kr-85 Pu-241 U-235 Ce-142 La-139 Pu-242 U-236 Ce-143 La-140 Pu-244 U-237 Ce-144 Mo-100 Rh-103 U-238 Cm-242 Mo-95 Rh-105 Xe-131 Cm-243 Mo-98 Ru-101 Xe-133 Cm-244 Mo-99 Ru-102 Xe-134 Cm-245 Nd-143 Ru-103 Xe-136 Cm-246 Nd-144 Ru-106 Y-91 Cm-247 Nd-145 Sb-125 Zr-93 Cs-133 Nd-147 Sb-126 Zr-94 Cs-134 Nd-148 Se-79 Zr-95 Cs-135 Np-236 Sm-147 Zr-96 Cs-136 Np-237 Sm-148 Cs-137 Np-238 Sm-149 Table 4.7-MPS3 Region 3 Depletion History 50 GWd/MTU KENO Region 3 Results Avg Depletion Boron boron Decay Non-conservatism Method (ppm)

Burnup Time k-inf.

k-ratio (pcm)

Constant 914 50 0

0.887499 0.00004 251 Letdown 991 50 0

0.889478 0.00004 N/A Constant 991 50 0

0.889186 0.00004 37