Text

GL 2004-02 Final Supplemental Response
	ML082700499
Person / Time
Site:	Arkansas Nuclear
Issue date:	09/15/2008
From:	Mitchell T; Entergy Operations
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	0CAN090801, GL-04-002
	Download: ML082700499 (111)
	v • d • e

EEntergy Operations, Inc.

7~1¶flf1448 S.R. 333

LLIwn, Russellville, AR 72802 Tel 479-858-3110 Timothy G. Mitchell Vice President, Operations Arkansas Nuclear One 0CAN090801 September 15, 2008 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Subject:

GL 2004-02 Final Supplemental Response Arkansas Nuclear One - Units 1 and 2 Docket Nos. 50-313 and 50-368 License Nos. DPR-51 and NPF-6

Dear Sir or Madam:

By letter dated February 28, 2008 (0CAN020803), Entergy provided a preliminary supplemental response to Generic Letter (GL) 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors (PWRs)," dated September 13, 2004 (OCNA090401), for Arkansas Nuclear One (ANO). By letters dated June 27, 2008 (1CNA060802) and April 30, 2008 (0CNA040804), the NRC approved a request for an extension of the final supplemental response by September 15, 2008, for ANO-1 and ANO-2, respectively.

Attachments 1 and 2 provide the final supplemental response to GL 2004-02 for ANO-1 and ANO-2, respectively.

A revised commitment contained in this submittal is summarized in Attachment 3. If you have any questions or require additional information, please contact Dale James at 479-858-4619.

I declare under penalty of perjury that the foregoing is true and correct. Executed on September 15, 2008.

TGM/nbm Attachments: ANO-1 Supplemental Response ANO-2 Supplemental Response List of Regulatory Commitments Ak1M

0CAN090801 Page 2 cc:

Mr. Elmo E. Collins Regional Administrator U. S. Nuclear Regulatory Commission Region IV 612 Lamar Blvd., Suite 400 Arlington, TX 76011-4125 NRC Senior Resident Inspector Arkansas Nuclear One P.O. Box 310 London, AR 72847 U.S. Nuclear Regulatory Commission Attn: Mr. Alan B. Wang MS 0-7 D1 Washington, DC 20555-0001 OCAN090801 ANO-1 Supplemental Response to

-0CAN090801 Page 1 of 50 ANO-1 Supplemental Response

1. Overall Compliance Provide information requested in Generic Letter GL 2004-02, "Requested Information,"

Item 2(a) regarding compliance with regulations. That is, provide confirmation that the emergency core cooling system (ECCS) and containment spray system (CSS) recirculation functions under debris loading conditions are or will be in compliance, with the regulatory requirements listed in the Applicable Regulatory Requirements section of GL 2004-02. This submittal addresses the configuration of the plant that will exist once all modifications required for regulatory compliance have been made and the licensing basis has been updated to reflect the results of the analysis.

By letter dated June 27, 2008 (1CNA060802), the NRC approved a request for an extension of the completion date of August 15, 2008, with the final supplemental response by September 15, 2008. The design change package (EC-2243) updating the ANO-1 design basis associated with GSI-191 resolution and Generic Letter 2004-02 compliance was approved by Entergy August 12, 2008, along with an associated ANO-1 Safety Analysis Report (SAR) revision provided to licensing. This submittal provides the final supplemental response for compliance with the regulatory requirements in GL 2004-02.

2. General Description of and Schedule for Corrective Actions Provide a general description of actions taken or planned, and dates for each. For actions planned beyond December 31, 2007, reference approved extension requests or explain how regulatory requirements will be met as per "Requested Information" Item 2(b). That is, provide a general description of and implementation schedule for all corrective actions, including any plant modifications, which were identified while responding to GL 2004-02.

During the fall 2005 steam generator (SG) replacement outage (1 R1 9), a significant amount of insulation was changed in the SG cavities from fiber or particulate insulation to reflective metal insulation (RMI). This removed'the vast majority of the detrimental debris materials from the SG cavities. During the spring 2007 'refueling outage (1 R20), the original sump screen (approximate surface area of 200 ft2) was replaced with a new engineered sump strainer. The replacement sump strainer is a modular design and has a surface area of approximately 2715 ft2. Also, additional insulation replacements and modifications were made in '1R20. This effort removed additional detrimental debris materials and added banding to calcium-silicate insulation to reduce its associated zone-of-influence (ZOI). In December 2007, a design modification was implemented to reduce the concentration of the sodium hydroxide (NaOH) chemical buffer. The concentration was reduced to a value within the current technical specification (TS) allowable range to support the updated chemical effects analysis. The reduced NaOH concentration is being administratively controlled until a license amendment request is approved. The license amendment request was submitted on July 30, 2008 (1CAN070801). The NaOH concentration reduction maintains final sump pH below 9.0, which reduces aluminum corrosion and the associated formation of chemical -precipitates.

to OCAN090801 Page 2 of 50

3. Specific Information Regarding Methodology for Demonstrating Compliance 3.a Break Selection The objective of the break selection process is to identify the break size and location that present the greatest challenge to post-accident sump performance.

1. Describe and provide the basis for the break selection criteria used in the evaluation.

2. State whether secondary line breaks were considered in the evaluation (e.g., main steam and feedwater lines) and briefly explain why or why. not.

3. Discuss the basis for reaching the conclusion that the break size(s) and locations chosen present the greatest challenge to post-accident sump performance.

3.a.1 Baseline Break Selection The ANO-1 nuclear steam supply system (NSSS) is a Babcock and Wilcox two-loop pressurized water reactor (PWR). The system consists of one reactor vessel, two SGs, four reactor coolant pumps (RCPs), one pressurizer, and the reactor coolant system (RCS) piping. The NSSS system is located inside a bioshield which consists of two SG cavities (D-ring) and one reactor cavity. Each SG cavity houses one SG and two RCPs. The north SG cavity houses the pressurizer. The outer walls of the D-ring extend from the reactor building base elevation (El.)

336'-6" to El. 424'-6". The reactor building sump is located on the north side of the reactor building on the 336'-6" elevation partially inside the D-ring.

Break locations were selected in accordance with the guidance criteria outlined in Nuclear Energy Institute (NEI) 04-07. The piping runs considered for breaks were the RCS hot legs, the RCS cold legs, and the RCS attached energized piping. Breaks in these lines could decrease RCS inventory and result in the ECCS and/or reactor building spray (RBS) system operating in recirculation mode. Table.3a-1 provides the breaks and break inside diameter (ID) that were postulated for the north cavity, and Figure 3.a.1-1 provides the break locations.

Table 3.a-1 Postulated Break Locations (Note 1)

Break Break Location Description SG Name ID (in)

Cavity S1 36 Hot Leg, lower North S2 8.75 Pressurizer Surge Line North S3 28 Cold Leg, upper North S4 36 Hot Leg, upper North

$5 28 Cold Leg, lower North S6 (Alt.)

11.188 Alternate Break North

-- El--

L I

iNote 1: i ne postulated, DreaK iocaions Iliste were ror tne nortn cavity, comparaDle DreaK locations were postulated in the south cavity, except S2 and S6.

to OCAN090801 Page 3 of 50 NL.&J

" 1 :

North S/

Sout*"*;

h S/G Breaks $1 & 6 Vse Figure 3.a.1-1 ANO-1 Break Locations 3.a.2 Secondary Line Breaks.

Recirculation is not required for feedwater line breaks or main steam line breaks; therefore, breaks in the main steam and feedwater lines were not analyzed.

3.a.3 Size and Location Conclusion The. "limiting" break is identified as the break that results in the type, quantity, and mix of debris generation that produces the maximum head loss across the sump strainer. This ensures that the analysis was bounding and presents the greatest challenge to post-accident sump performance.

The hbt leg (S1 and S4) is the largest line (36-inch ID) within the SG cavity and produces the largest ZOI. :'Initially higher insulation debris totals existed in the north SG cavity, which includes the pressurizer. Subsequent outage *modification work to reduce fiber and calcium-silicate insulation resulted in the south~SG cavity having the largest insulation debris totals for both fiber and calcium-silicate insulation materials.

The cold legs (Breaks S3 and S5) have a smaller diameter than the hot leg. However, the cold legs extend much lower in the SG cavities than the hot legs and affect insulation and debris sources that were lower in the SG cavity.

Break S5 was analyzed to capture the coating on the D-ring floor and insulation sources with smaller ZOIs located low in the SG cavity as the other postulated break locations were too high to impact the reactor building floor.

The pressurizer Surge line connection to the pressurizer was analyzed as break S2.

Due to the removal of fibrous and particulate insulation from the SG cavities as well as banding efforts to reduce the ZOI for many of the remaining lines, the detrimental insulation types are scattered in a few discrete locations *within the cavities. Following the' second round of insulation reduction modifications (1R20, *sPring 2007) the north SG cavity (containing the pressurizer) was no longer limiting with regard to maximum fiber and particulate debris generation. Modeling of the r'emaining non-RMI lines in the south SG cavity was required to determine a limiting break locatiOn for the two cavities. With the addition of banding to reduce to OCAN090801 Page 4 of 50 the insulation ZOI; additional break locations were added to the model to ensure maximum debris generation was evaluated for the various types of fiber and particulate debris.

Fiber is a key component for establishing maximum possible strainer head loss. Therefore, the breaks with the largest amount of fiber were considered. Since no single break produced the largest amount of the different fiber insulation types (i.e., Temp-Mat, high density fiberglass (HDFG), thermal wrap, ceramic fiber) the total mass of fiber generated by the breaks were included in the debris generation tables for comparison. Four breaks; lower hot leg (S1), upper A-cold leg (S3), upper hot leg (S4), and the lower A-cold leg (S5), in the south SG cavity were found to have the largest fiber loads and only varied by approximately 10% in total fiber mass.

The other principal consideration for selecting the most limiting break was the amount of calcium-silicate insulation generated.

A series of head loss sensitivity tests were conducted. The amount of calcium-silicate insulation was a significant contributor to elevated head loss when combined with a thin-bed fiber condition. The four breaks producing the largest amount of fiber insulation were in the South cavity. These four breaks had more significant variations in the amount of calcium-silicate insulation released. The calcium-silicate insulation volumes were limited, but the S4 break (upper hot leg break) produced considerably more than the next most limiting break. Break S5 produced'the most fiber (rieference Table 3.b.4-1) but generated less calcium-silicate insulation debris. The other breaks produced slightly more fiber but generated less calcium-silicate compared to break S4. Thus, the greatest combination of both fiber and calcium-silicate insulation was created by break S4, which was the most limiting break for strainer head loss testing. The strainer head loss qualification tests included bounding quantities of each debris type, as noted in Table 3.f.5-1. The additional debris loading provides margin for any future changes to the debris generation analysis and bounds the maximum amount of debris from any combination of breaks.

3.b Debris Generation/ZOI (excluding coatings)

The objective of the debris generationlZOI process is to determine, for each postulated break location: (1) the zone within which the break jet forces would be sufficient to damage materials and create debris; and (2) the amount of debris generated by the break jet forces.

1. Describe the methodology used to determine the ZOIs for generating debris.

Identify which debris analyses used approved methodology default values. For debris with ZOIs not defined in the guidance report/safety evaluation (SE), or if using other than default values, discuss method(s) used to determine ZOI and the basis for each.

2. Provide destruction ZOIs and the basis for the ZOIs for each applicable debris constituent.

3. Identify if destruction testing was conducted to determine ZOIs. If such testing has not been previously submitted to the NRC for review or information, describe the test procedure and results with reference to the test report(s).

4. Provide the quantity of each debris type generated for each break location evaluated. If more than four break locations were evaluated, provide data only for the four most limiting locations.

5. Provide total surface area of all signs, placards, tags, tape, and similar miscellaneous materials in containment.

to OCAN090801 Page 5 of 50 3.b.1 ZOI Methodology The ZOI radii for applicable insulation materials were in accordance with NEI 04-07. When ZOIs for identified materials or the installed configuration was not provided in NEI 04-07, ZOI destructive testing was performed or conservative bounding ZOls were applied based on similarities with other materials. ZOIs that were not obtained from the guidance document are listed below:

The ZOI for calcium-silicate insulation listed in NEI 04-07 was based upon tests performed with banded lagging. Portions of the lagging at ANO are fastened with sheet metal screws instead of banding which was considered a potentially non-conservative variation from the ZOI for calcium-silicate with banded lagging. Westinghouse performed jet impingement testing at Wyle Labs test facility in order to establish a ZOI consistent with the methodologies documented in NEI 04-07 for calcium-silicate insulation covered with screwed rather than banded lagging. A test conducted at an equivalent distance of a 25D ZOI was used to conservativelyestablish the ZOI for this configuration'.

There was no guidance regarding the ZOI for Thermal-Wrap fiber and HDFG insulation either with or without banding; therefore, the ZOI for Thermal-Wrap Fiber and HDFG, if covered with lagging retained by sheet metal screws, was set equal to that of calcium-silicate insulation covered with lagging fastened by sheet metal screws (25D). This ZOI was conservative since the tested lagging over calcium-silicate insulation and fastened with screws did not fail at the 25D ZOI equivalent distance.

" The original Transco RMI insulation includes a few small sections with Temp-Mat insulation instead of the reflective metal foil. Where this material was covered with standard Transco jacketing.and fasteners similar to the surrounding RMI, a ZOI of 2.0D was applied. The 2.0D ZOI for Transco RMI from NEI 04-07 guidance was applicable since the interior insulation would not be released unless the outer jacketing was first dislodged. Where the Temp-Mat was not covered with'Transcojacketing it was conservatively assumed to become debris for the breaks in the'SG cavity where the insulation was located.

Thermal wrap insulation on pipe that has been covered with stainless steel (SS) lagging and includes banding was assumed to have a ZOI of 5.45D. This was conservatively taken from the ZOI in NEI 04-07 for banded calcium-silicate insulation based on testing conducted by the Ontario Power Group (OPG). Application of this ZOI was considered conservative since stainless steel lagging is used at ANO versus aluminum lagging in the OPG tests, with the aluminum lagging having been the source of failure. The thermal wrap blanket provides an additional barrier against release of the internal fiberglass batting.

to 0CAN090801 Page 6 of 50 3.b.2 Destruction ZOI and Basis See Table 3.b.2-1.

Table 3.b.2-1 Destruction ZOIs and Basis Debris Sources ZOI Basis Transco RMI 2.OD NEI 04-07 Temp-Mat (with RMI jacketing) 2.0D Note 1 Thermal-Wrap Fiber 25D Note 1 Thermal-Wrap Fiber (SS cladding, SS banding) 5.45D Note 1 HDFG 25D Note 1 Calcium-silicate (SS cladding, SS banding) 5.45D NEI 04-07 Calcium-silicate (SS Cladding w/ screws) 25D Note 1 Note 1: See section 3.b.1.

3.b.3 Destruction Testinq Destructive testing of the calcium-silicate insulation with screwed rather than banded lagging was conducted by Westinghouse at the Wyle Labs test facility for. The ZOI from the destructive testing of calcium-silicate insulation was also applied to HDFG and Thermal Wra'l fiber insulation materials similarly covered with SS lagging fastened with sheet metal screws, since a conservatively bounding ZOI was established from the test.

The Westinghouse tests were documented in WCAP-16836-P, Revision 0. The experimental program used a facility with fluid supply pressure of 2000 psia and temperature of 530'F discharging from a 3.54-inch nozzle. The test pipe placement in front of the jet was calculated using the ANSI N58.2-1988 jet expansion model. Testing compensated for a slightly lower supply pressure by locating the test articles relative to the jet nozzle such that the stagnation pressure at the point of jet impingement in the test was calculated to be the same as with a supply pressure of 2250 psia. The calcium-silicate insulation on pipe was covered with SS lagging fastened with sheet metal screws and was tested at 33.82 ft from the nozzle with the seam at a 45-degree angle from the nozzle.' The testing did not result in a breach of the lagging material and none of the calcium-silicate insulation was ejected or exposed following the test. Thus, the tested configuration provides a conservative bounding value for damage.

3.b.4 Debris Type Quantity See Table 3.b.4-1 for the'three breaks in the south cavity with the largest debris totals and for comparison the north cavity break with the largest fiber debris total.

to OCAN090801 Page 7 of 50 Table 3.b.4 Summary of Loss-of-Coolant Accident (LOCA)-Generated Debris South South South North Debris Type Units Break Break Break Break S1 S4 S5 S1 Transco RMI Foil ft2

<15,000

<6,000

<2,000

<15,000 Transco Temp Mat t

<5

<5 Calcium-silicate ft3

<10

<12.5

<5

<10 HDFG Insulation W

<10

<15

<10 Thermal-Wrap Insulation

<5

<10

<5 Cera-Fiber Insulation ft3

<1

<1 Penetration Blanket Fiber (Note lbs

<5

1)

___-c_<_<_<

Total Fiber (Notes 2 and 3) lbs

<70

<80

<50 Note 1: Fabric blankets are installed over the RCS cold leg pipe penetrations into the SG cavities with 10% of the blanket weight credited as. becoming fiber fines.

Note 2: Since no single break produces the largest amount of all fiber sources, and different fabricated densities can make comparisons difficult, the total fiber mass or weight (excluding latent fiber) is provided for comparison bounded by the nearest unit of ten.

Note 3: The fiber densities used to determine total fiber mass were 11.8 Ib/ft3 for Temp-Mat, 4.5 lb/ft3 for HDFG, 2.4 lb/ft3 for Thermal-Wrap, and 8 lb/ft3 for cera-fiber.

3.b.5 Miscellaneous Materials The total surface area of transportable signs, placards, tags, tape, and similar foreign materials in the reactor building following efforts to remove these potential debris sources is less than 100 ft2. In accordance with the guidance in NEI 04-07 and the associated SE, 75% of the single-sided surface area of foreign materials would obstruct the sump strainer surface area.

This results in an even smaller net obstruction of screen surface area, providing significant margin to the 200 ft2 allowed-for foreign material blockage in the strainer qualification tests.

3.c Debris CharacteristicSs The objective of the debris characteristics determination process is to establish a conservative debris characteristics profile for use in determining the transportability of debris and its contribution to head loss.

1. Provide the assumed size distribution for each type of debris.

2. Provide bulk densities (i.e., including voids between the fibers/particles) and material densities (i.e., the density of the microscopic fibers/particles themselves) for fibrous and particulate debris.

3. Provide assumed specific surface areas for fibrous and particulate debris.

4. Provide the technical basis for any debris characterization assumptions that deviate from NRC-approved guidance.

3.c.1 Size Distribution Reductions in strainer debris loading associated with transport reduction for insulation or coatings debris was conservatively not credited. The insulation debris generated by the postulated breaks was considered to have 100% transport to the strainer. The size distribution of the debris used for strainer head loss testing was conservatively based to maximize strainer head loss potential. Calcium-silicate insulation was pulverized into fines/powder. Fiber insulation was shredded into fines and very small pieces. Coatings surrogates were powder/fines other than a small amount of chips used to represent a portion of the damaged qualified coating that was outside the ZOI. This treatment of debris characteristics was conservative relative to the guidance provided in NEI 04-07.

to 0CAN090801 Page 8 of 50 3.c.2 Bulk Densities The bulk and material densities for fibrous and particulate debris were consistent with those reported in NEI 04-07. For the specific materials at ANO-1, the following bulk and material densities were used:

Bulk Density Material Density Calcium-silicate ýlbm/ft 3) 14.5 144 Temp-Mat (Ibm/ft°)

11.8 162 HDFG (lbm/ft3) 4.5 159 Thermal-Wrap (lbm/ft3) 2.4 159 Cera-Fiber (lbm/ft3) 8.0 156 to 158 Qualified Coating - Epoxy (lbm/ft3) 94 n/a Qualified Coating - Primer (lbm/ft 3) 205 n/a Unqualified Coating (lbm/ft3) 94 n/a The bulk density of inorganic zinc primer (205 lbm/ft3) was obtained from Carboline for their CZ-1 1 zinc primer. This value was a more accurate representation of the dry film density of zinc primer versus the value provided in NEI 04-07, which.was for pure zinc powder without any fillers or binders used in the primer compound.

3 c.3 Surface'Areas Surface area assumptiOns Were not applicable to the strainer qualification testing performed for ANO-1. The particulate size used for the coatings surrogate was 600-mesh which was in the nine-micron size range to approximately match the ten-micron size for coatings particulate discussed in NEI 04-07. The coatings surrogates are further discussed in section 3.h.

3.c.4 Debris Characterization Deviations The sump strainer qualification was performed with a bounding case that conservatively assumed 100% transport of all insulation and coating debris potentially generated following a LOCA. Therefore, these debris types have not been evaluated for characteristics with regard to transportability. Debris characteristics for strainer head loss testing have been considered and comply with the guidance provided in NEI 04-07.

3.d Latent Debris The objective of the latent debris evaluation process is to provide a reasonable approximation of the amount and types of latent debris existing within the containment and its potential impact on sump screen head loss.

1. Provide the methodology used to estimate quantity and composition of latent debris.

2. Provide the basisý for assumptions used in the evaluation.

3. Provide results of the'latent debris evaluation, including amount of latent debris types and physical data for latent debris as requested for other debris.

4. Provide amount of sacrificial strainer surface area allotted to miscellaneous latent debris.

3.d.1 Latent Debris Methodology Walkdowns were performed in order to collect samples throughout the reactor building on a wide Variety of surfaces and at various elevations to document potential debris quantity and composition in accordance with NEI 02-01. Latent debris surveys have been performed in two consecutive outages at ANO-1 with consistent results.

to OCAN090801 Page 9 of 50 3.d.2 Basis for Assumptions In accordance with NEI 04-07, 15% of the latent debris was comprised of fiber and the remaining 85% was comprised of particulate. It was assumed that the debris was normally distributed for a given sample type. This assumption was supported by plant walkdown observations that debris distribution appeared to be uniform for a given surface type.

3.d.3 Evaluation Results Based on data collected in the walkdowns, the amount of latent debris was less than 150 Ibm.

Margin exists in the strainer qualification testing and downstream effects analysis for fiber and particulate loading above currently calculated debris generation quantities as noted in Table 3.f.5-1. This margin can be used to address larger latent debris, totals in the future, if necessary.

3.d.4 Sacrificial Strainer Surface Area Strainer qualification testing assumed that 200 ft2 of surface area is blocked by miscellaneous latent debris.

3.e Debris Transport The objective of the debris transport evaluation process is to estimate the fraction of debris that would be transported from debris sources within containment to the sump suction strainers.

1. Describe the methodology used to analyze'debris transport during the blowdown,wash down, pool-fill-up, and recirculation phases of an accident.

2. Provide the technical basis for assumptions and methods used in the analysis that deviate from the approved guidance.

3. Identify any computational fluid dynamics (CFD) codes used to compute debris transport fractions during recirculation and summarize the methodology, modeling assumptions, and results.

4. Provide a summary of, and supporting basis for, any credit taken for debris interceptors.

5. State whether fine debris was assumed to settle and provide basis for any settling credited.

6. Provide the calculated debris transport fractions and the total quantities of each type of debris transported to the strainers.

3.e.1 Debris Transport Methodoloqy The sump strainer head loss testing was performed with a bounding case that conservatively assumed 100% transport of all insulation, latent, and coating debris types potentially generated following a LOCA. No credit was taken for debris potentially trapped in gratings, structures or upper elevations. No credit was taken for debris being swept into inactive volumes during pool fill-up.

The current analysis conservatively assumes 100% transport of miscellaneous latent debris (i.e., tape, stickers, etc.) of the type materials identified as credible sources. It is anticipated that additional sources of miscellaneous latent debris could possibly continue to be identified beyond those currently considered. Future disposition of miscellaneous latent debris is expected to include credit for settling, transportability, or lift velocities on a case-by-case basis.

3.e.2 Deviations No deviations were taken, from the approved guidance, other than the conservative use of 100%

transport of insulation and coating debris to the sump screen following a LOCA. Strainer testing determined that RMI debris was causing a potentially non-conservative effect on strainer head loss and was therefore excluded from final qualification tests. This is discussed in section 3.f.

to OCAN090801 Page 10 of 50 This deviation was considered a conservative bias to maximize strainer head loss and was not related to debris transport analysis.

3.e.3 CFD Codes While a CFD code was used to evaluate flow velocities in the reactor building basement, it was not subsequently used to justify reductions in debris transport analysis.

3.e.4 Debris Interceptors No credit was taken in the transport analysis for debris interceptors.

3.e.5 Settling The debris transport fraction for insulation and coating debris was assumed to be 100%. No credit was taken for settling of insulation or coating debris, 3.e.6 Debris Transport Fractions 100% of all insulation, latent, and coating debris were credited with transport to the sump follbwing a LOCA. Miscellaneous latent debris materials may be evaluated for transport reduction in the future as noted in 3.e.1. For debris quantities refer to Table 3.b.4-1, as well as sections 3.b.5 and 3.d.3.

to 0CAN090801 Page 11 of 50 3.f Head Loss and Vortexing The objectives of the head loss and vortexing evaluations are to calculate head loss across the sump strainer and to evaluate the susceptibility of the strainer to vortex formation.

1. Provide a schematic diagram of the ECCS and CSS.

2. Provide the minimum submergence of the strainer under small-break LOCA (SBLOCA) and large-break LOCA (LBLOCA) condition.

3. Provide a summary of the methodology, assumptions and results of the vortexing evaluation. Provide bases for key assumptions.

4. Provide a summary of the methodology, assumptions, and results of prototypical head loss testing for the strainer, including chemical effects. Provide bases for key assumptions.

5. Address the ability of the design to accommodate the maximum volume of debris that is predicted to arrive at the screen,

6. Address the ability of the screen to resist the formation of a "thin-bed" or to accommodate partial thin-bed formation.

7. Provide the basis for the strainer design maximum head loss.

8. Describe significant margins and conservatisms used in the head loss and vortexing calculations.

9. Provide a summary of the methodology, assumptions, bases for the assumptions, and results for the clean strainer head loss calculation.

10. Provide a summary of the methodology, assumptions, bases for the assumptions, and results for the debris head loss analysis.

11. State whether the sump is partially submerged -or vented (i.e., lacks a complete water seal over its entire surface) for any accident scenarios and describe what failure criteria in addition to loss of net positive suction head (NPSH) margin were applied to address potential inability to pass the required flow through the strainer.

12. State whether near-field settling was credited for the head-loss testing and, if so, provide a description of the scaling analysis used to justify near-field credit.

13. State whether temperature/viscosity was used to scale the results of the head loss tests to actual plant conditions. If scaling was used, provide the basis for concluding that boreholes or other differential-pressure induced effects did not affect the morphology of the test debris bed.

14. State whether containment accident pressure was credited in evaluating whether flashing would occur across the strainer surface, and if so, summarize the methodology used to determine-the available containment pressure.

to OCAN090801 Page 12 of 50 3.f.1 Schematic Diagrams Figure 3f.1-1 ANO-1 Schematic of the Engineered Safeguards System 7V~

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to 0CAN090801 Page 13 of 50 3.f.2 Minimum Submergence The minimum reactor building flood level was used to determine the submergence of the strainer, which was greater than seven inches. The minimum reactor building flood level does not credit release of RCS inventory, but does include inventory from the core flood tanks (CFTs). The minimum level was conservative relative to LBLOCA scenarios. While it would be possible for a SBLOCA to occur that does not result in release of the CFTs, but subsequently results in sump recirculation, such a condition would result in significantly lower debris generation and flow velocities. Thus, strainer head loss would be expected to be minimal with such a SBLOCA. The strainer would remain fully submerged even if the CFT inventory is excluded from the sump inventory.

3.f.3 Vortexinq Evaluation The vortexing evaluation was accomplished by comparing the ANO-1 sump strainer design against the parameters of a proven design. The proven design relied on test data to show that vortices were not present.

The vortex analysis used physical test data to demonstrate that strainers with un-perforated cover plates did not exhibit any vortexing. During these tests, the lowest water coverage above the strainers was 0.035 m (1.38 in).

Using the Froude number, the testing data can be used to calculate the water coverage which was sufficient to preclude air vortexing. The Froude number is a ratio of dynamic pressure (the driving force of vortexing) to a static pressure (the water head above the screen). The Froude numbers can be used to calculate a scaled minimum submergence, which was less than one inch for the ANO-1 design conditions.

The water cover over the top elevation of the strainer while at the post-LOCA minimum water level was greater than seven inches. The water coverage of the strainer exceeds both the minimum water coverage in the tests and the calculated scaled minimum submergence needed to preclude vortexing. Because the actual minimum sump strainer coverage exceeds both the tested and calculated mi'nimum coverage necessary to preclude vortexing, there exists significant margin in protection against vortexing. It was therefore concluded that adequate protection against vortices exist for the sump strainer.

3.f.4 Head Loss Testinq Strainer qualification testing was performed at a test flume facility constructed by Fauske and Associates using strainer cartridges fabricated by CCI. The test facility consisted of two strainer cartridges installed in a tank with a recirculation pump and instrumentation for measurement of flow and head loss. The installed strainer cartridges were identical to those installed in ANO-1, with a total surface area of approximately 54 ft2 compared to an installed screen surface area of approximately 2715 ft2. An allowance of 200 ft2 was deducted from the installed screen for foreign material debris blockage, for a net available surface area of 2515 ft2. Since credit was not taken for near-field settling the flow through the test facility was scaled based on the strainer area ratio and bounding maximum two-train flows. This established a maximum velocity through the strainer openings consistent with what would be present with the installed strainer.

The debris and chemical loading was determined using this same scaling ratio.

Debris materials in the credited qualification test consisted of calcium-silicate insulation consistent with newer material installed in the plant (original calcium-silicate contained asbestos fibers), HDFG, Thermal-Wrap fiberglass, Transco Temp-Mat fiberglass, and silicon-carbide as a surrogate for coatings and latent particulate. Paint chips of Carboline 890 coating were also used and were sieved to obtain a size small enough to maximize transportability but large to OCAN090801 Page 14 of 50 enough to potentially block the 1/1 6-inch strainer openings. Chemical precipitate (sodium aluminum silicate (NAS)) was added after the debris-only head loss results were established to determine the head loss associated with chemical effects. Early sensitivity tests included additional debris types including RMI foils, cera-fiber, and zinc powder.

The use of silicon-carbide grit as a surrogate test material for coatings and latent particulate is discussed in section 3.h.3. The silicon-carbide grit used for testing properly reflected the particle size recommended for strainer head loss testing.for both coatings and latent particulates and the density for latent particulates as discussed in the guidance document. The variation in material density between the silicon-carbide surrogate and density of coatings represented was conservatively bounded by the amount of silicon-carbide used in the test facility to ensure an adequate volume'of material was used, not just a scaled mass.

The fiber materials used in the final strainer qualification testing included a mixture of high density (11.8 Ibs/ft3) Transco Temp-Mat fiberglass, low density (2.4 lb/ft3) Transco Thermal-Wrap fiberglass, and high density pre-formed pipe fiberglass (4.5 lb/ft3), which were specific matches to the principal source materials for remaining fiber insulation released by the limiting breaks. The final qualification test did not specifically include cera-fiber insulation (8 Ib/ft3). This was considered acceptable since the cera-fiber quantity for the limiting-break was considerably less than one ft3, which would equate to less than 0.1 lbs in the test facility, and the test had ample excess fiber to address this amount from fiber sources that included both higher and lower density materials.

Debris Preparation and Addition:

Lessons learned from NRC observations at various vendor test facilities were incorporated into the test methodology applied. Debris preparation included pulverizing the calcium-silicate into fines, shredding the fiber insulation into fines and very small pieces. The fiber fines were soaked in water to have them in suspension prior to addition to the flume in order to avoid having material floating on the surface of the flume. The fibers were also separated into multiple containers to avoid a concentrated mix of fibers that could re-agglomerate into larger clumps prior to being added to the test loop. The fiber addition buckets were not mixed with any other material to maximize the transport and distribution of the fibers. The silicon-carbide was ordered as 600-mesh (nine-micron average) and did not require processing. The RMI foils used in early tests were shredded and crumpled prior to addition. Paint chips were sieved to achieve 2mm to 4 mm (1/12" to 1/6") size pieces.

Debris addition was performed in sequences with the fiber material added first and stirred as needed until essentially all material was transported into the strainer. The calcium-silicate insulation was added next, followed by the silicon-carbide and paint chips. Near-field settlement of test debris in the strainer facility was avoided by stirring to achieve as close to complete transport into the strainer cartridges as possible. Stirring was performed manually with care taken not to disrupt or disturb the debris bed established inside the strainer pockets, but only as needed to re-suspend settled materials from the test flume floor in front of the strainer. The stirring was repeated periodically as needed to re-suspend settled materials. After some period of time the test facility water would become clearer due to particulate filtration, providing visual evidence that the vast majority of the test debris had entered the strainer cartridges.

Confirmation that the remaining settled debris (i.e., trace particles and paint chips) was not consequential to strainer head loss was provided by the absence of increasing head loss peaks following repeated stirring.

Testing was not conducted for 30 days; however, head loss was monitored to ensure maximum head loss values had been reached. The debris beds for ANO-1 include thin fiber beds of to OCAN090801 Page 15-of 50 approximately 1/8" thickness, if evenly distributed. Since debris preparation involved shredding the fibers into fines and small pieces, which was then poured ina water solution into a flowing flume, formation of a thin-bed was expected. Filtering clean-up of the test flume water provided confirmation of thin-bed type filtration combined with the elevated head loss measurements.

Head loss typically remained at near zero values after the fiber was added but increased following addition of calcium-silicate and silicon-carbide surrogate particulate. The head loss characteristics of the debris beds produced an initial peak in head loss once essentially all debris was transported into the strainer, but the head loss subsequently decreased over time to a relatively stable value.

Since the head loss characteristics of the debris bed did not show an increasing trend over time, and the early peak value was used for qualification, there was no need to run extended duration tests. The fiber bed with 100% debris loading remains relatively thin (approximately 1/8") and therefore does not support compaction due to settling or potential breakdown of fibers. The initial settling of the particulate and fiber bed resulted in a reduction in the peak head loss with a, stable value typically reached within the first few hours of operation. Earlier sensitivity tests of longer duration did not indicate that the head loss increased with increased time, therefore qualification tests were shortened to approximately 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The final qualification test included approximately 20 hours2.314815e-4 days 0.00556 hours 3.306878e-5 weeks 7.61e-6 months of operation with debris only conditions, followed by 13 days of additional testing involving additions of chemical precipitate materials and head loss monitoring.

Head Loss Test Results/Data Analysis:

The-results of the strainer qualification tests show that the strainer head loss remains below the available NPSH margin and-the structural limits. The results of strainer head loss testing with and without chemical effects are provided below. Detailed discussion of the chemical effects analysis is included in section 3.o.

Maximum Head Loss with Debris Only (w/o Chemical Effects):

<1 ft (at equivalent test flow > maximum analyzed flow)

Maximum Allowable Head Loss without Chemical Effects:

>4 ft Maximum Head Loss with Chemical Effects Debris (Extrapolated):

<8 ft (at lequivalent flow > maximum analyzed flow)

Maximum Allowable Head Loss with Chemical Effects Debris:

>10.5 ft (based on strainer structural head loss limit)

The strainer testing maximum head loss values were conservatively taken from peak head loss reading versus the lower stable values.

3.f.5 Debris Loadinq The strainer cartridges can hold the entire debris load predicted by the debris generation calculation with the exception of RMI foils. The dominant insulation type was RMI with essentially all of the RCS, SG, and pressurizer insulation being RMI. The RMI foil volume would not fit into the strainers and was found to have either non-conservative or negligible effect on strainer head loss. The material does not readily lay flat against the strainer perforated plate. It forms a three dimensional layer or pile that can act as a pre-filter that catches fibers and other debris types, keeping them off of the strainer surface. The foil can also bury insulation that was on the floor of the test facility. If the non-RMI debris was added first and time was allowed for it to enter the strainer (which is non-prototypic) then the problem of burying other insulation types under RMI can be avoided, but even in this configuration the RMI fragments would be expected to OCAN090801 Page'16 of 50 to puncture and disturb the established fiber and particulate debris bed and cause a reduction rather than an increase in head loss. Final qualification tests were conducted without RMI foils as a conservative measure to maximize head loss.

The strainer head loss qualification tests included bounding volumes of fiber, calcium-silicate, coatings and particulate debris to allow margin for future changes to the debris generation totals. This approach bounds the largest combination of fiber sources, calcium-silicate insulation, coatings, and other debris sources from any combination of the evaluated breaks as outlined below:

Table 3.f.5 Comparison of Debris Generation to Strainer Test Debris Loads South South South North Strainer Debris.Type Units Break Break Break Break Test

$1 S4 S5 Sl Latent Fiber lbs

<25

<25 Total Fiber (incl. latent) lbs

<95

<100

<75 115.5 Calcium-silicate ft

<10

<12.5

<5

<10 14.5 Coatings (qual. & unqual.)

ft3

<3.5

<3.5 4.2 Latent Particulate lbs

<150

<150 170 3.f.6 Thin-Bed Effect Testing has shown that "thin-bed" formation can and does occur with the ANO-1 strainer. Due to the limited fiber source term, insufficient material exists to create thicker (i.e., > 1/8") fiber beds. Thus, none of the issues related to thick fiber beds were applicable to ANO-1. Issues such as settling or compaction, differences in head loss characteristics with chemical precipitates versus debris only, as well as debris addition sequencing for maximum thick-bed head loss do not apply due to the low available fiber content.

The strainer qualification tests established thin-bed conditions, but with acceptable head loss results. Without the formation of a thin-bed, the screen would be left with open area and minimal resulting head loss. The head loss with the thin-bed alone, without particulate material, was also minimal. The particulate filtering capability of the strainer thin-bed was confirmed both by. increased head loss and filtration of the test water to essentially clear conditions after sustained operation, with visual observation and stirring of the test flume floor confirming that the particulate had not simply settled out. Earlier tests had shown than thin-bed conditions could be established with considerably smaller fiber thicknesses, however, these "ultra'thin-bed" layers did not produce as large a strainer head loss and would develop blow-holes or jetting through the debris bed at a lower head loss and therefore were not the most conservative condition for maximum strainer head loss comparison.

3.f.7 Maximum Head Loss The strainer design maximum head loss was controlled by two principal parameters; NPSH margin and structural qualification. NPSH margin was the limiting parameter when sump water temperatures were at, or above 197°F. The limiting NPSH margin was greater than four feet which was the maximum allowable head loss early in the accident response time period whený temperatures were above 197°F.

When sump temperatures were below 197°F, the NPSH margin exceeds the maximum structural head loss design limit. Thus, the sump structural design stress which can withstand differential pressure loading of at least 10.5 ft was the limiting parameter for head loss when to 0CAN090801 Page 17 of 50 sump temperatures were below 1970F. Structural qualification of the strainers is discussed in section 3.k.

3.f.8 Margins Some of the more significant margins and conservatisms used in the strainer head loss calculations and strainer testing are as follows:

Strainer tests were able to achieve much greater uniformity of debris loading than would be expected in the plant. Debris was added at the top of the test flume with flow present and stirring was used to maintain debris suspended throughout the flow path. This allowed a much greater degree of uniform debris distribution than would be expected with strainer assemblies that are over four feet in height and oriented in four different directions. Given the relatively low available fiber and particulate loads, a non-uniform distribution of the debris would be expected to result in open screen or screen surface with such low debris content that it does not cause a pressure drop. The majority of the debris would not be expected to remain in suspension during the approximate half-hour period when the basement fills with water. Debris traveling on the floor would have limited ability to lift multiple feet to cover the upper strainer cartridges. Qualification testing intentionally tried to achieve the worst case or most conservative results by maximizing the potential for uniform debris distribution. This controlled processing and application of the debris in the test facility was considered to be a very conservative and non-prototypic bias applied to the qualification tests.

100% of fiber debris was assumed to be reduced to fines or very small pieces, which were credited with 100% transport. A significant portion of the fiber debris (other than latent) would likely be released as large pieces (40% was conservatively-noted in NEI 04-07 for several types of fiber). Industry testing conducted on several fiber types have shown that erosion fractions for these large pieces were small, which would support a significant reduction in available fiber loading. A portion of the fiber debris could reasonably be expected to be trapped in grating in the SG cavity, dislodged RMI foils, or other debris in the basement region below the break. No credit for these realistic reductions in fiber loading on the strainers was applied. This conservatism was significant for ANO-1 based on the relatively low available fiber, since a fiber layer of only approximately 1/8" was present with 100% transport to the screens as small pieces and fines. Reductions in fiber loading would increase the potential for open screen, or even if perfectly distributed, would result in a thinner fiber bed with lower resulting head loss.

Calcium-silicate debris generation used a 25D ZOI for un-banded material (screwed lagging). This ZOI was conservatively established from an impingement test that did not breach the lagging or expose any internal insulation.

Banded calcium-silicate assumes a 5.45D ZOI based on OPG testingperformed with weaker aluminum jacketing, which was the source of failure. ANO banded calcium-silicate uses stainless steel lagging which includes banding and sheet metal screws, thus providing margin relative to the applied ZOI.

to OCAN090801 Page 18 of 50

" Calcium-silicate insulation was assumed to erode 100% into fines with 100% transport to the screens. Testing conducted for ANO has indicated that a significant portion of the large calcium-silicate pieces would not erode into fines. In addition, tests indicated that calcium-silicate fines would not be expected to achieve 100% transport. No credit was taken for these reductions in calcium-silicate volume. This was a significant conservatism given the limited calcium-silicate source and its significant affect on strainer head loss. Small reductions associated with lower erosion and/or transport values or reductions due to other causes such as material trapped under RMI or swept into inactive flow regions, if credited, could result in lower strainer head loss.

RMI was excluded from the flume testing which was considered a non-prototypic conservatism since the large volume of potentially released RMI would be expected to bury, trap, or filter some of the other debris types and limit the material reaching the strainers.

The minimum reactor building water level does not credit water lost from the RCS even though it was being applied to LBLOCA conditions for NPSH and strainer head loss.

" Shadowing was only, credited for large components such as the SGs and pressurizer, while the congested SG cavities include RCP motors, large structural steel beams, and other barriers to direct jet impingement that were not credited, but would realistically limit the large ZOls from impacting more distant pipes.

" No viscosity correction was applied to the head loss measured at ambient temperature used for comparison with NPSH head loss limits, which were only applicable to sump temperatures of 197°F or higher.

The peak chemical effects head loss at one-train equivalent flow was less than the available minimum NPSH margin without applying viscosity corrections. (While noted as a "conservatism", this measured head loss was not being credited against the pump NPSH conditions, but is only noted as a comparative point.)

The projected peak chemical effects head loss with two-train maximum flow would be below the available NPSH margin if corrected for the lower viscosity at elevated temperature. (While noted as a "conservatism", this head loss was not being credited against the pump NPSH conditions, but is only noted as a comparative point.)

to OCAN090801 Page 19 of 50 Strainer head loss qualification tests used debris quantities that significantly exceeded the amounts determined by the debris generation calculation as noted in Table 3.f.5-1.

These excess amounts were added to establish margin that could be credited to allow for future modifications, material discoveries, degradation or other issues. Therefore, the excess tested material was not a conservatism with respect to being unavailable as useable margin, but it did show that the ANO-1 test results bound conditions in the plant with margins sufficient to allow future adjustments to the supporting analysis without impacting the strainer testing maximum head loss values.

See section 3.f.3 for vortexing margin discussion.

3.f.9 Clean Strainer Head Loss The clean head loss of the strainer cartridges themselves was negligibly low at maximum flow conditions, which was confirmed by strainer testing. The internal head loss for the overall strainer assembly was dominated by the exit losses from the strainer assembly openings into the sump pit. Since this loss was not reflected in the strainer head loss tests, it was included as a reduction of the available NPSH in the pump NPSH calculation.

3.f.10 Debris Head Loss Analysis See section 3.f.4. Results of the strainer debris head loss prototypic testing indicate a maximum head loss of less than one foot. Analytical techniques were not credited for establishing the maximum strainer head loss.

3.f.11 Submergence/Venting The sump has a complete water seal over its entire surface and is not vented above the water level for the events requiring recirculation. Water cover over the entire surface of the sump exceeds seven inches. No additional failure criteria were applied.

3.f.12 Near-Field Settlinq The debris addition process during strainer qualification testing did not credit near-field settling.

The debris materials were manually stirred to, achieve as close to complete transport into the strainer cartridges as possible (i.e., only trace particles or isolated paint chips visible in flume and continued stirring was not causing a head loss increase), thereby avoiding near-field settling.

3.f.13 Head Loss Scalinq Scaling of head loss results to correct for temperature related viscosity differences between test and accident conditions was conservatively not credited, with ambient temperature head loss testing. Earlier strainer tests with larger head loss exhibited blow-holes or jetting streams of water through the strainer, which tended to affect the head loss response to velocity changes.

Velocity changes were made in various tests to evaluate the responsiveness of the debris bed to head loss. If poor head loss responsiveness to velocity change exists, then it was believed that a similar lack of responsiveness to reduced viscosity would also exist and therefore the test results for that condition would not be suitable for viscosity correction. The jetting effect was particularly evident with higher head loss conditions (two-plus feet) combined with very thin fiber beds, which was believed to be due to the debris bed reaching a structural limitation at a given head loss with an equilibrium being reached by breaches or perforations in the bed developing.

Most of the tests with lower head loss did not exhibit this perforated debris bed jetting and their head loss was responsive to flow changes. The debris only test results were considered acceptable for application of viscosity corrections based on both visual observation during the test (via lack of blow through conditions) and the responsiveness of the debris bed head loss to flow changes.

to OCAN090801 Page 20 of 50 3.f.14 Accident Pressure Credit The sump strainer is not vented above the water level and has a complete water seal over its entire surface for the events requiring recirculation. Minumum water cover over the strainer assemblies exceeds seven inches.

The maximum sump strainer head loss based on testing applicable to elevated sump temperature conditions was less than one foot. For the few inches difference in the sump strainer head loss and available submergence, credit was taken for the reactor building post-accident overpressure to show that the sump water temperature would be sub-cooled and flashing would not occur. A relatively slight increase in reactor building pressure (< 0.25 psi) needs to be credited. One degree of sub-cooling is equivalent to approximately 0.3 psig overpressure at 212°F and atmospheric conditions. The LBLOCA building temperature profile shows a minimum sub-cooling condition of approximately 4.50F at a sump fluid temperature of 2520F, following the initial turnover of sump fluid after the start of recirculation. This magnitude of sub-cooling would be equivalent to an overpressure condition of approximately 2.35 psi, compared to <0.25 psi needed to avoid flashing. The building response analysis shows that as the sump continues to cool following this period, the magnitude of sub-cooling or equivalent overpressure increases significantly.

The methodology used to determine the reactor building overpressure or sump sub-cooling following a LBLOCA noted above is from the current design bases accident analysis that assumes single-train operating conditions. While the analysis is not intended to evaluate the worst-case combination of events and equipment responses that would maximize sump temperature and minimize reactor building pressure, it does provide a reasonable comparison of the magnitude of sump sub-cooling margin that exists for avoiding flashing across the sump strainer. Other events and equipment combinations that involve smaller breaks and/or loss of pump operation would cause significant reductions in the amount of debris generated by the break as well as smaller flows through the sump strainer. Both of those changes would reduce the sump strainer differential pressure.

Additional significant factors supporting the conclusion that flashing would not occur across the sump strainer include the strainer head loss being measured at ambient temperature conditions and not corrected for viscosity. The viscosity correction alone could reduce the temperature head loss to a value well below the available submergence. The minimum submergence level does not credit RCS inventory, consistent with an SBLOCA, while.the credited head loss can only be achieved from debris resulting from a LBLOCA condition, which would result in significant additional inventory release into the reactor building. As previously noted, an SBLOCA would result in minimal strainer debris loading that would not result in sufficient head loss to exceed the available submergence.

The larger head loss across the strainers associated with chemical effects was shown not to exist until further sub-cooling of the sump temperatures occur and therefore,. did not create an increased flashing potential.

to OCAN090801 Page 21 of 50 3.g Net Positive Suction Head The objective of the NPSH section is to calculate the NPSH margin for the ECCS and CSS pumps that would exist during a LOCA considering a spectrum of break sizes.

1. Provide applicable pump flow rates, the total recirculation sump flow rate, sump temperature(s), and minimum containment water level.

2. Describe the assumptions used in the calculations for the above parameters and the sources/bases of the assumptions.

3. Provide the basis for the required NPSH (NPSHr) values, e.g., three percent head drop or other criterion.

4. Describe how friction and other flow losses are accounted for.

5. Describe the system response scenarios for LBLOCA and SBLOCAs.

6. Describe the operational status for each ECCS and CSS pump before and after the initiation of recirculation.

7. Describe the single failure assumptions relevant to pump operation and sump performance.

8. Describe how the containment sump water level is determined.

9. Provide assumptions that are included in the analysis to ensure a minimum (conservative) water level is used in determining NPSH margin.

10. Describe whether and how the following volumes have been accounted for in pool level calculations: empty spray pipe, water droplets, condensation and holdup on horizontal and vertical surfaces. If any are not accounted for, explain why.

11. Provide assumptions (and their bases) as to what equipment will displace water resulting in higher pool level.

12. Provide assumptions (and their bases) as to what water sources provide pool volume and how much volume is from each source.

13. If credit is taken for containment accident pressure in determining available NPSH, provide description of the calculation of containment accident pressure used in determining the available NPSH.

14. Provide assumptions made which minimize the containment accident pressure and maximize the sump water temperature.

15. Specify whether the containment accident pressure is set at the vapor pressure corresponding to the sump liquid temperature.

16. Provide the NPSH margin results for pumps taking suction from the sump in recirculation mode.

3.g.1 Flow Rates, Temperature, and Water Level See Tables 3.g.1-1 and 3.g.1-2.

Table 3.g.1-1 Pump Flow and Total Recirculation Sump Flow Rates Low-Pressure Injection (LPI) pump maximum flow* (per pump) 3547 gpm RBS pump maximum flow (per pump) 1320 gpm Maximum sump flow rate (two-train operation) 9734 gpm Minimum reactor building water level

>4.9 ft

Listed flow rate does not include 100 gpm pump protection recirculation flow.

NPSH for the LPI and RBS pumps has been evaluated as a function of sump water temperature which varies with time. Thus, the available margin was determined as a function of time starting with recirculation through 30 days post-LOCA. Recirculation begins at 4000 seconds following a LOCA.

to OCAN090801 Page 22 of 50 Table 3.g.1-2 Sump Fluid Data Time (sec)

Temperature (OF) 4,000 259.00 10,000 252.40 50,000 223.90 60,000 219.00 70,000 213.90 80,000 208.40 90,000 202.00 100,000 197.00 200,000 175.00 300,000 162.00 400,000 157.00 500,000 153.00 1,000,000 136.00 2,000,000 127.50 2,500,000 123.90 3.g.2 Assumptions The following assumptions were applied to the parameters in section 3.g.1 at the maximum time-dependent sump temperature.

Pump flow rates represent maximum values per design calculations.

The sump water temperatures were taken from the reactor building post-LOCA temperature analysis, which assumes loss of one train of equipment, maximum cooling water temperatures, and minimum guaranteed available flows, which provides the longest duration of elevated temperature conditions.

The maximum per pump flow rates given in Table 3.g.1-1 for both the LPI and RBS pumps were bounding for either one-train (i.e., single failure) or two-train flow configurations.

See section 3.g.9 for minimum water level assumptions' 3.g.3 NPSHr Basis Required NPSH for the LPI and spray pumps was taken from the certified pump curves in the technical manuals. The specific basis for the NPSHr term provided by the pump vendor was not specified in the vendor technical documents.

3.g;4 Friction and Other Flow Losses The sump temperature and corresponding fluid density were used to calculate the Reynolds Number which subsequently was used to calculate frictional losses in suction piping for both the LPI and RBS pumps. Frictional losses through the suction piping were calculated by taking pipe dimensions and resistance factors to determine losses through the piping system. Since sump temperature varies with time, frictional loss versus time was calculated and used in the analysis.

3.g.5 System Response System response was determined by break size and resulting RCS and reactor building pressure characteristics. The high-pressure injection (HPI) pumps and LPI pumps are actuated when RCS pressure decreases to 1585 psig and/or the reactor building pressure reaches 18.7 psia. If the reactor building pressure reaches 44.7 psia the spray system automatically actuates.

to OCAN090801 Page 23 of 50 3.g.6 Pump Status The initial injection of water by the HPI, LPI, and RBS systems involves pumping water from the borated water storage tank (BWST) into the reactor vessel and reactor building. When the BWST reaches an indicated level of six feet, the operator opens the suction valves from the reactor building sump permitting recirculation of the spilled reactor coolant and injection water and closes the BWST outlet valves. The RBS pump flow is throttled prior to transfer of pump suction from the BWST to the sump. HPI pumps are secured prior to transfer of pump suction to the sump for LBLOCA conditions. For SBLOCA conditions the LPI pumps take suction from the sump and discharge to the suction of the HPI pumps in "piggy-back" operating mode,,until RCS pressure is reduced sufficiently below the LPI pump shutoff head allowing them to supply RCS injection directly. Therefore, the more limiting NPSH condition occurs with only LPI and RBS pumps aligned to the sump, since this condition maximizes flow through the LPI pumps and sump strainer.

3.g.7 Single Failure Assumptions The principal design criterion for the LPI and RBS systems includes separate and independent flow paths as well as redundancy in active components, to ensure that the required functions are performed if a single failure occurs. The worst-case single failure for the LBLOCA analysis with regards to the maximum reactor building pressure and temperature profile and the ability to provide adequate core cooling flow was the loss of an ECCS train, The systems are designed to perform their required function assuming a single failure. For conservatism related to worst case NPSH and sump strainer head loss, both trains of LPI and RBS were assumed to be operational during recirculation to maximize flow. The HPI pumps were not assumed in operation, since they would only be used for SBLOCA conditions, which are less limiting for pump NPSH and strainer head loss, as noted in section 3.g.6. HPI is manually secured for LBLOCA response prior to transfer of pump suction to the sump by steps that stop the HPI pumps as well as close the HPI block valves, thus providing redundancy in isolation of HPI.

3.g.8 Sump Water Level The minimum reactor building sump water level was determined by calculating three parameters:

Gross volume in the lower elevations of the reactor building

Volume of structures, systems, or components (SSCs) in the lower elevations of the building which offsets part of the gross volume

Volume of water which comprises the reactor building sump water inventory In determining the volume offset by SSCs, credit was taken for volume's occupied by various tanks, supports, concrete walls, piping, miscellaneous steel, pumps, etc. To determine the conservative minimum amount of sump inventory, borated water injection was equal to the design minimum, water vapor was maximized, as were surfaces assumed to be wetted. Only CFT water inventory was assumed released from the RCS. The shrink of the entire RCS inventory due to density changes associated with cooling the RCS is included in minimum level determination.

3.g.9 Conservative Assumptions The following conservative assumptions were used:

Minimum CFT and BWST volumes were used.

Makeup and storage tank volume was assumed to be zero.

NaOH discharge into the RBS system was minimized by assuming a single failure of an outlet valve from the tank such that only 4000 gallons was released prior to to OCAN090801 Page 24 of 50 transfer to sump recirculation. (This was also the assumption for minimum sump pH analysis.)

Holdup in the refueling canal was credited.

Water trapped as steam was accounted for per SBLOCA analysis (0.085 ft2 break) conditions at start of recirculation.

Wetted surface was maximized.

Volume of falling RBS water in air was maximized.

No water was assumed released from the RCS (other than from CFTs).

Shrinkage of the full RCS volume due to density change was included.

3.g.10 Volumes Spray piping was assumed empty downstream of the pump discharge motor-operated valve.

The minimum water level calculation accounted for water d&oplets using an average droplet size for expected RBS flow rate during recirculation. Drag forces were calculated to determine the terminal velocity of the water droplets. An average fall height was determined based on the spray header locations. Condensation and holdup on horizontal and vertical surfaces were accounted for by water trapped on wetted surfaces and holdup in the refueling canal. Total surface area of 350,000 ft2 was credited for determining water holdup with an assumed water thickness of 1/8".

3.g.11 Water Displacement The following equipment was credited with displacing pool volume:

" Two SG supports and SGs Reactor pedestal and instrument tunnel walls

" Cold legs

" Columns Elevator shaft and walls Secondary shield walls 0

Block walls Quench tank and drain tanks Letdown coolers Stairs and strainer assembly 3.g.12 Water Sources The minimum water level was determined by first calculating the water available and then subtracting the trapped water that does not reach the reactor building floor. See Tables 3.g.12-1 and 3.g.12-2.

Table 3.g. 12-1 Gross Available Water for Minimum Reactor Building Water Level Source I

ft3 F

Ib, Ii CFTs 1,660 102,000 Makeup and Storage Tank 0

0 BWST 42,256 2,610,000 Sodium Hydroxide Tank 535 33,100 RCS 11,494 473,520 Total Water Sources 55,945 3,220,000 to OCAN090801 Page 25 of 50 Table 3.a.12-2 Trapped Water to Determine Net Available Water for Minimum RB Level Source Ibm Refueling Canal 86,500 RCS 673,0001 RBS Header 23,100 Water Held Up as Steam 64,500 Water on Wetted Surfaces 215,000 Spray Water in Air 10,000 Thtal Wat*.r Tr~nn*.d 1 N70 NoN RCS trapped water mass is greater than initial mass to reflect higher density of cooler RCS volume.

Note: Supporting assumptions are discussed in section 3.g.9.

3.g.13 Reactor Building Accident Pressure No credit was taken for the reactor building accident pressure in the NPSH analysis.

3.g.14 Reactor Building Accident Pressure Assumptions Reactor building accident pressure was not credited.

3.g.15 Vapor Pressure The minimum post-accident reactor building pressure was set equal to the minimum pressure allowed by TS (13.7 psia). The saturation temperature corresponding to this minimum reactor building pressure (208.40F) was then established as the limiting sump pool temperature for purposes of determining NPSH available., For sump pool temperatures above the limiting temperature, reactor building pressure was set equal to the saturation pressure (i.e., vapor pressure) corresponding to the sump pool temperature. For sump pool temperatures at or below the limiting temperature, reactor building pressure was set equal to the minimum post-accident reactor building pressure (13.7 psia).

3.g.16 NPSH Margin Results The NPSH margins for the LPI and RBS pumps are listed in Table 3.g.16-1. These numbers have been calculated using clean strainer head loss.

Table 3.q.16-1 NPSH Margin Pump NPSH Margin Pump__(ft)

A Train LPI

>5 B Train LPI

>4.5 A Train RBS

>5.5 B Train RBS

>4 As can be seen from the above table, the most limiting pump NPSH margin for clean strainer conditions during recirculation was four feet, which establishes the maximum allowable strainer head loss at elevated sump temperature (i.e., saturated water) conditions. Table 3.g.16-2 provides temperature based NPSH margin for the B Train RBS pump.

NPSH margin for the most limiting pumps in terms of NPSH margin is shown in Table 3.g.16-2.

These values do not include all calculated values for NPSH margin but include the minimum NPSH values for the most limiting pump starting with recirculation at approximately 4,000 seconds. NPSH for the LPI and RBS pumps has been evaluated as a function of sump water temperature which varies with time. The sump temperature decreases after recirculation.

When the sump reaches a post-recirculation temperature of 208.4 0F, the pre-accident minimum to OCAN090801 Page 26 of 50 reactor building pressure was credited. For sump temperatures above this value, the NPSH margin improves slightly due to the reduced viscosity and density as temperatures increase.

Once the sump water cools below 208.40F, the NPSH margin increases rapidly since the additional NPSHa from the sub-cooled water vapor pressure was much greater than the detrimental effects from viscosity and density increases.

Table 3.g.16-2 NPSH Margin for Spray pump P35B Time (seconds)

NPSH Margin (ft)

Sump Temp. (OF) 1,000

>4.1 281 4,000

>4.1 259 80,000

>4.0 208 90,000

>8.0 202 100,000

>10.8 197 200,000

>20.5 175 300,000

>24.5 162 400,000

>25.8 157 3.h Coatings Evaluation The objective of the coatings evaluation section is to determine the plant-specific ZOI and debris characteristics for coatings for use in determining the eventual contribution of coatings to overall head loss at the sump screen.

1. Provide a summary of type(s) of coating systems used in containment, e.g.,

Carboline CZ 11 Inorganic Zinc primer, Ameron 90 epoxy finish coat.

2. Describe and provide bases for assumptions made in post-LOCA paint debris transport analysis.

3. Discuss suction strainer head loss testing performed as it relates to both qualified and unqualified coatings and what surrogate material was used to simulate coatings debris.

4. Provide bases for the choice of surrogates.

5. Describe and provide bases for coatings debris generation assumptions. For example, describe how the quantity of paint debris was determined based on ZOI size for qualified and unqualified coatings.

6. Describe what debris characteristics were assumed, i.e., chips, particulate, size distribution and provide bases for the assumptions.

7. Describe any ongoing containment coating condition assessment program.

3.h.1 Coating Systems in the Reactor Buildinq Tables 3.h.1-1, 3.h.1-2, and 3.h.1-3 list the various qualified coatings that may exist within the reactor building.

Table 3.h.1-1 Qualified Liner Steel Coatings COATING DCRPTING COATING TYPE DESCRIPTION Ameron Dimecote 6 Carboline CZ-1 1 Ameron Amercoat 90 Intermediate Coat Carboline 890 Carboline 954 Ameron Amercoat 90 Final Coat Ameron No. 1741 Carboline Phenoline 305 Carboline No. 3912 to OCAN090801 Page 27 of 50 Table 3.h.1-2 Qualified Equipment/Support and Piping Steel Coating COATING DCRPTING COATING TYPE DESCRIPTION Ameron Amercoat 90 Ameron Dimecote 6 Primer Coat Carboline CZ-1 1 Carboline 890 Carboline 954 Ameron Amercoat 90 Intermediate Coat Carboline 890 Carboline 954 Ameron Amercoat 90 Final Coat Ameron No. 1741 Carboline No. 3912 Table 3.h.1-3 Qualified Concrete Floor Coating COATING DCRPTING COATING TYPE DESCRIPTION Carboline Starglaze 2011S Ameron NU-KLAD 105 Carboline Starglaze 2011S Carboline Carbocrete Intermediate Coat D1340HS Carboline 890 Carboline 954 Carboline 890 Carboline 948 Carboline 954 Ameron NU-KLAD 110 AA Unqualified coatings exist on a variety of components inside the reactor building such as valves, valve actuators, instrumentation, etc. The potential volume of this material has been calculated and included in the debris total for coatings debris generation. All of the unqualified coatings were assumed to fail. No credit was taken for the Electric Power Research Institute (EPRI) original equipment manufacturer (OEM) coatings testing program.

3.h.2 Assumptions in Post-LOCA Paint Debris Transport ANO testing assumed 100% transport of all coating debris materials to the sump screen.

3.h.3 Suction Strainer Head Loss Testinq Strainer head loss testing is further discussed in section 3.f. Coatings materials were represented by 600-mesh black silicon-carbide grit for suction strainer head loss testing. Paint chips of Carboline 890 coating were also used and were sieved to obtain a size small enough to maximize transportability but large enough to potentially block the 1/16-inch strainer openings.

Unqualified coatings and qualified coatings (epoxy top coat) were modeled with 600-mesh silicon-carbide, which was approximately a nine-micron size particle and was generally consistent with the ten-micron characteristic particle size recommend to represent the coatings particles.

The measured material density for the silicon-carbide was 167 Ib/ft3, which was higher than the coating material density of 94-98 lb/ft3 noted in Table 3-3 of NEI 04-07 for epoxy and alkyd to OCAN090801 Page 28 of 50 coatings. The variation in material density between the silicon-carbide surrogate and density of coatings represented was conservatively bounded by the amount of silicone carbide used in the test facility to ensure an adequate volume of material was used, not just a scaled mass.

Silicon-carbide was selected as a surrogate material based on its availability in the small particle size. Also, the density of silicon-carbide was near that of paint pigments, and was not chemically reactive with other debris sources in the test facility (hydrogen gas was evolved by reaction between chemical precipitate surrogates and zinc filler used in earlier head loss sensitivity tests, causing storage and waste disposal issues).

The selection of particulate debris to create greatest head loss impact was based on the formation of thin-bed filtration conditions during the tests. Strainer tests were consistently able to establish particulate filtering thin-beds, thus, the use of particulates was considered conservative. An additional portion of paint chips (approximately equivalent to one half cubic foot of paint chips in the reactor building, scaled to the flume test size) beyond the amount of coatings debris determined in the debris generation calculation was also added to the test facility. It was not considered credible that all coating debris would be generated as particulate, particularly degraded qualified coatings outside the ZOI, which were assumed to fail. While the transport of paint chips was significantly less likely than the small particulate material, the addition of some portion of paint chips was done as an additional conservative measure or margin that may be credited if needed to address future coating degradation.

3.h.4 Surroqates See section 3.h.3 for bases for choice of surrogates.

3.h.5 Coatings Debris Generation Assumptions Entergy has utilized WCAP-16568-P, "Jet Impingement Testing to Determine the ZOI for DBA-Qualified Coatings" for determining qualified coatings ZOI values. From this report Entergy has applied a ZOI of 4D for qualified epoxy coatings and a ZOI of 5D for qualified inorganic zinc coatings. The associated break models have assumed that qualified coatings on steel materials within the 4D ZOI region have both primer (inorganic zinc) and top coat (epoxy) coatings to maximize the coating debris quantity within this region. Since only zinc primer coatings were affected in the region between 4D and 5D from the break, steel surfaces with qualified coatings were assumed to have only primer in this region. For areas where the actual coating thickness was not available, the coating thickness was conservatively taken as the maximum possible coating thickness specified by the ANO coating specification.

For floor coating, the 4D ZOI radius was truncated in accordance with NEI 04-07. The area projected on the floor and the total volume of qualified coating debris generated by each break was calculated. The reactor building wall inside the D-rings is not coated.

The quantity of steel coating debris generated by break S1 (lower hot leg) in the north cavity was assumed to bound the coating debris generated by other breaks, since break S1 was on the largest pipe (36" ID) and it was centrally located within the SG cavity that includes the pressurizer. This volume of generated steel coating debris was conservatively applied to all breaks.

3.h.6 Debris Characteristic Assumptions See section 3.h.3 for bases for debris characteristic assumptions.

to 0CAN090801 Page 29 of 50 3.h.7 Coating Condition Assessment Programs Qualified coatings are controlled under site procedures. The strainer qualification testing and downstream effects analysis included margin for additional coating debris. The coatings program includes periodic inspection walkdowns in containment to identify damaged or degraded coatings. Entergy repairs or assesses damaged qualified coatings to ensure that the quantity of coatings in the qualification documents is not exceeded.

3.i Debris Source Term The objective of the debris source term section is to identify any significant design and operational measures taken to control or reduce the plant debris source term to prevent potential adverse effects on the ECCS and CSS recirculation functions. Provide the information requested in GL 2004-02 Requested Information Item 2(f) regarding programmatic controls taken to limit debris sources in containment. That is, provide a description of the existing or planned programmatic controls that will ensure that potential sources of debris introduced into containment (e.g., insulations, signs, coatings, and foreign materials) will be assessed for potential adverse effects on the ECCS and CSS recirculation functions. Specifically, provide the following:

1. A summary of the containment housekeeping programmatic controls in place to control or reduce the latent debris burden. Specifically for RMI/low-fiber plants, provide a description of programmatic controls to maintain the latent debris fiber source term into the future to ensure assumptions and conclusions regarding inability to form a thin-bed of fibrous debris remain valid.

2. A summaryof the foreign material exclusion programmatic controls in place to control the introduction of foreign material into the containment.

3. A description of how permanent plant changes inside containment are programmatically controlled so as to not change the analytical assumptions and numerical inputs of the licensee analyses supporting the conclusion that the reactor plant remains in compliance with IOCFR50.46 and related regulatory requirements.

4. A description of how maintenance activities including associated temporary

.changes are assessed and managed in accordance with the Maintenance Rule, 1 OCFR50.65.

If any of the following suggested design and operational refinements given in the guidance report (section 5) and SE (section 5.1) were used, summarize the application of the refinements.

5. -Recent or planned insulation change-outs in the containment which will reduce the debris burden at the sump strainers

6. Any actions taken to modify existing insulation (e.g.,jacketing or banding) to reduce the debris burden at the sump strainers

7. Modifications to equipment or systems conducted to reduce the debris burden at the sump strainers

8. Actions taken to modify or improve the containment coatings program 3.i.1 Reactor Building Debris Generation Assumptions Reactor building walkdowns were performed to determine the amount of latent dirt and dust in the building. Measurements were taken during the refueling outages prior to extensive cleaning being performed in preparation for building closeout. Thus, the latent debris values were considered to be conservative. These cleaning activities are consistent with normal housekeeping practices and associated administrative requirements.

Attachment I to 0CAN090801 Page 30 of 50 By letter dated August 30, 2005 (0CAN080501), Entergy committed to the measurement of latent debris quantities every third refueling outage to confirm that latent debris quantities used in strainer testing and downstream effects analysis remain bounding. As noted in that letter the plant may choose to relax this frequency after the first measurements, provided the results indicated that an adequate level of cleanliness was maintained. This commitment is being clarified to describe the planned process. The results of the initial two inspections will be compared to the margins available for latent debris and provided adequate margin remains the inspection frequency and scope may be relaxed. The sample scope may be reduced to two samples of each of the representative surface types and the frequency extended from every third outage to every fourth outage. If subsequent inspections reveal that housekeeping and cleanliness measures continue to maintain latent debris loading below the tested/evaluated values with sufficient margin, then the inspection frequency could be extended to a maximum interval of every sixth outage (not to exceed ten years). If inspection results reveal an adverse trend in latent debris quantities such that latent debris margin for the tested and analyzed conditions are unacceptably reduced, then the inspection frequency will be shortened and the scope increased as appropriate to ensure adequate margin is maintained.

Both the strainer qualification tests and the downstream effects analysis included fiber and particulate quantities greater than the measured values for latent debris to ensure that margin exists to bound possible future variations in latent debris measurements.

3.i.2 Foreign Material Exclusion (FME) Programmatic Controls Maintenance processes are in place to control materials used in the reactor building. These processes reduce the creation of foreign materials. Following refueling outages, a reactor building closeout procedure is in place to inspect the reactor building (including the sump) to ensure that foreign materials are addressed.

3.i.3 Permanent Plant Changes Inside the Reactor Building The Entergy.procedure for control of design modifications includes a list of design input considerations. This list includes specific items which address insulation and coatings in the reactor building and any modification which may affect sump performance to ensure the plant continues to meet 10CFR50.46 and related regulatory requirements. Additional detail has also been added to configuration control documents such as insulation specifications and isometric drawings to note the credited configuration relative to sump analysis.

3.i.4 Maintenance Rule Maintenance activities are planned, scheduled, and implemented within the bounds of 10CFR50.65. Maintenance involving insulation or coating is performed in accordance with engineering approved specifications. Temporary modifications are controlled using the same design input considerations a permanent modification uses.

3.i.5 Reactor Building Insulation Change-Outs During refueling outage 1 R19 (fall 2005), actions were taken to reduce potentially detrimental insulation types in the SG cavities during the SG replacement project. Fiber and calcium-silicate insulation were removed from the RCS, feedwater, and main steam piping in the SG cavities and replaced with RMI. This effort removed the vast majority of the detrimental debris materials from the SG cavities. Actions were again taken in the 1 R20 refueling outage (spring 2007) to replace additional sections of thermal wrap fiber insulation with RMI on piping and reactor coolant pumps as well as removal of fiber insulation from other piping.

to 0CAN090801 Page 31 of 50 3.i.6 Existing Insulation Modification Modification of existing insulation was performed during refueling outage 1 R20 (spring 2007).

This consisted of the addition of banding to calcium-silicate and thermal wrap insulation lagging (original lagging fastened with sheet metal screws) to reduce the ZOI to 5.45D.

3.i.7 Equipment/System Modification No equipment or system modifications were necessary.

3.i.8 Reactor Building Coatings Proqram Modification A site procedure controls ANO commitments related to its safety-related coatings program. This procedure provides the minimum requirements at ANO to ensure that coatings are properly selected, applied, and maintained so the coatings can perform their intended function without negatively impacting the safety functions of other SSCs. This procedure addresses the activities related to service-level I coatings inside the reactor building where the coating failure could adversely affect the operation of the post-accident fluid systems and thereby impair safe shutdown. The coatings program has been upgraded in response to the GL 2004-02 response by expanding the focus beyond the liner plate to include periodic walkdown inspections of all readily accessible coatings in containment to assess damage or degradation.

3.j Screen Modification Package The objective of the screen modification package section is to provide a basic description of the sump screen modification.

1. Provide a description of the major features of the sump screen design modification.

2. Provide allist of any modifications, such as reroute of piping and other components, relocation of supports, addition of whip restraints and missile shields, etc., necessitated by the sump strainer modifications.

3.j.1 Sump Screen Design Modification The sump screen design modification removed the original sump screen, vortex eliminator, carbon steel divider plate, and concrete curb with scuppers. The original screen was replaced with a new CCI strainer assembly. The new strainer assembly consists of modular screen cartridges with perforated 1/16-inch holes. The screen fits over the sump and has a footprint which is slightly larger than the nominal dimensions of sump. The new replacement strainer has a surface area of approximately 2715 ft 2 compared to the original screen area of approximately 200 ft2.

The new sump strainer assembly and divider plate (including the integral screen) were fabricated from stainless steel to preclude corrosion and eliminate the need for protective

,coatings. The original vortex eliminator was removed and not replaced. The bottom of the strainer floor plate is approximately one inch higher than the reactor building floor. A stainless steel divider plate similar to the original divider plate was installed inside the strainer. The divider plate has a stainless steel screened mesh opening between the two sump halves consisting of 0.132" (nominal) square openings.

3.j.2 Related Modifications In order to lower the profile of the strainer the original concrete curb surrounding the sump was removed. This curb contained scuppers that allowed water on the floor near the strainer to drain into the sump. To prevent ponding due to the replacement strainer, new drains with integral filters were bored to allow water to flow into the sump.

to OCAN090801 Page 32 of 50 3.k Sump Structural Analysis The objective of the sump structural analysis section is to verify the structural adequacy of the sump strainer including seismic loads and loads due to differential pressure, missiles, and jet forces. Provide the information requested in GL 2004-02 Requested Information Item 2(d)(vii). That is, provide verification that the strength of the trash racks is adequate to protect the debris screens from missiles and other large debris.

The submittal should also provide verification that the trash racks and sump screens are capable of withstanding the loads imposed by expanding jets, missiles, the accumulation of debris, and pressure differentials caused by post-LOCA blockage under flow conditions.

1. Summarize the design inputs, design codes, loads, and load combinations utilized for the sump strainer structural analysis.

2. Summarize the structural qualification results and design margins for the various components of the sump strainer structural assembly.

3. Summarize the evaluations performed for dynamic effects such as pipe whip, jet impingement, and missile impacts associated with high-energy line breaks (as applicable).

4. If a back-flushing strategy is credited, provide a summary statement regarding the sump strainer structural analysis considering reverse flow.

3.k.1 Design Inputs, Design Codes, Loads, and Load Combinations See Tables 3.k.1-1, 3.k.1-2, and 3.k.1-3 parameters.

Table 3.k.1-1 Structural Qualification Source Documents Input Document Description of Input ANO-1 Specification APL-C-501, Earthquake Seismic response spectra for the sump Resistant Design of Structures and/or Components Strain re Located in the Unit 1 Reactor Building strainer structure Provided allowable stresses for normal and upset conditions. Faulted stresses were limited to the following:

AISC, "Manual of Steel Construction, Allowable 0.90.Fy for tension and bending Stress Design,"

0.50.Fy for shear (Fy = specified minimum yield strength) 0.50"Pcr for compression where Pcr =

critical load (elastic or inelastic)

Provided yield and ultimate stresses for 2004 ASME Boiler & Pressure Vessel Code, materials used based on design Section II; Part D - Properties temperature for each load case.

ANO Design Guide, SES-18, "Concrete Anchor Provided allowable anchor bolt loads.

Bolt Design Criteria" Table 3.k.1-2 Structural Load Combinations oad LStress Limit Case Load Combination Load Category Factor 1

DL NORMAL 1

2 DL+ E UPSET 1

3 DL+ E' FAULTED 1.5 4

DL+ E'+ SLOSH FAULTED 1.5 5

DL+ DLD + E' + Ap + SLOSH FAULTED 1.5 6

DL + SHLD NORMAL 1

to OCAN090801 Page 33 of 50 Table 3.k.1-3 Nomenclature DL =' Dead Load Ap = Pressure differential across the screen E = Operating Basis Earthquake (OBE)

DLD = Debris Load F= Design Basis Earthquake (DBE)

SHLD = Temporary shielding (outages)

SLOSH = Water sloshing due to E' OBE and DBE loads were determined using site response spectra for the appropriate elevation.

Design temperatures for the ANO-1 sump structure can be summarized:

" Minimum sump water temperature during recirculation = 60OF

" Maximum sump water temperature during recirculation = 255°F

Maximum reactor building bulk average air temperature, normal = 120°F

" Maximum reactor building air temperature, accident = 2850F In addition to these load cases, the effects of temperature, differential seismic movement, hydrodynamic water masses, and buoyancy were addressed in the calculation.

3.k.2 Structural Qualification Results The analysis determined that the,maximum differential pressure that the screens and screen structure could sustain and remain code qualified was greater than 10.5 ft of water.

3.k.3 Dynamic Effects Also see section 3.k.1. The strainer assembly is primarily located in an opening at the base of the steam generator cavity wall. There were no credible jet impact hazards to the reactor building sump strainer, and there were no credible pipe whip effects to the sump. Walkdowns concluded that there were no credible missiles.

3.k.4 Back-Flushing A back-flushing strategy was not credited for ANO-1.

3.1 Upstream Effects The objective of the upstream effects assessment is to evaluate the flow paths upstream of the containment sump for holdup of inventory, which could reduce flow to and possibly starve the sump. Therefore, provide a summary of the upstream effects evaluation including the information requested in GL 2004-02, "Requested Information,"

Item 2(d)(iv) including the basisfor concluding that the water inventory required to ensure adequate ECCS or CSS recirculation would not be held up or diverted by debris blockage at choke-points in containment recirculation sump return flow paths.

1. Summarize the evaluation of the flow paths from the postulated break locations and containment spray wash-down to identify potential choke points in the flow field upstream of the sump.

2. Summarize measures taken to mitigate potential choke points.

3. Summarize the evaluation of water holdup at installed curbs and/or debris interceptors.

4. Describe how potential blockage of reactor cavity and refueling cavity drains was evaluated, including likelihood of blockage and amount of expected holdup.

3.1.1 Choke Points The sump pit is located below the north SG cavity at an opening on the north side of the D-ring wall. The flow path from a postulated break in the north cavity remains inside that cavity. The flow path from a south cavity break is from that cavity into the basement region between the two to OCAN090801 Page 34 of 50 SG cavities and then flowing into the sump strainer both through the north SG cavity and around the outside wall to the opening where the sump is located. RBS wash-down would fall through gratings to the basement from the areas inside and outside the SG compartments. Spray flow falling into the refueling canal region drains through an open six-inch pipe connection into the reactor cavity and incore tunnel and out through a locked open hatch into the basement. The refueling canal reactor cavity drainage paths have been evaluated to show that no potential debris blockage exists. No credit was taken for flow through normal floor drains. Therefore, no measures were necessary to mitigate potential choke points because none exist.

3.1.2 Choke Point Mitigation No curbs and/or debris interceptors are present and no flow choke points exist.

3.1.3 Water Holdup There are no curbs or debris interceptors installed; therefore, no water holdup analysis was necessary.

3.1.4 Reactor/Refuelinq Cavity Drain Blockage The refueling canal drainage path has been evaluated for potential debris blockage. No additional water hold-up beyond that currently assumed in the reactor building minimum level analysis was found to be necessary. Hold-up does not occur in the reactor cavity as it drains through a large open man-way.

The characteristics of the post-LOCA debris generated and deposited into the refueling canal do not obstruct drainage of RBS water inventory from the refueling canal to the reactor building sump. A maximum of approximately 11,000 gallons of RBS water was conservatively assumed to be retained in the refueling canal during post-LOCA conditions, based on spray flow that may fall into the refueling canal and the calculated head to support this flow rate out of the six-inch drain line in the wall of the deep end. The refuelinrg canal drain is configured to draw water from above the refueling deep end floor. Large and small debris would rest on the refueling canal floor with the expected drain flow rate. Fines and floating debris would be carried in the drain stream without obstructing or plugging the six-inch drain path. Complete blockage of the refueling canal deep end drain by post-LOCA generated debris was not credible based on the drain size, location, and geometry. Although large debris may migrate to the incore instrumentation tunnel access hatch opening during initial basement fill, it is not credible for large debris to be lifted up and block the open hatch.

3.m Downstream Effects - Components and Systems The objective of the downstream effects, components and systems section is to evaluate the effects of debris carried downstream of the containment sump screen on the function of the ECCS and CSS in terms of potential wear of components and blockage of flow streams. Provide the information requested in GL 2004-02, "Requested Information,"

Item 2.(d)(v) and 2.(d)(vi) regarding blockage, plugging, and wear at restrictions and close tolerance locations in the ECCS and CSS downstream of the sump by explaining the basis for concluding that inadequate core or containment cooling would not result due to debris blockage at flow restrictions in the ECCS and CSS flow paths downstream of the sump screen, (e.g., a HPSI throttle valve, pump bearings and seals, fuel assembly inlet debris screen, or containment spray nozzles). The discussion should consider the adequacy of the sump screen's mesh spacing and state the basis for concluding that adverse gaps or breaches are not present on the screen surface. Also, provide verification that the close-tolerance subcomponents in pumps, valves and other ECCS and CSS components are not susceptible to plugging or excessive wear due to extended post-accident operation with debris-laden fluids.

to 0CAN090801 Page 35 of 50

1. If NRC-approved methods were used (e.g., WCAP-16406-P, "Evaluation of Downstream Sump Debris Effects in Support of Generic Safety Issue (GSI)-1 91",

with accompanying NRC SE) briefly summarize the application of the methods.

2. Provide a summary and conclusions of downstream evaluations.

3. Provide a summary of design or operational changes made as a result of downstream evaluations.

3.m.1 NRC-Approved Methods The approved methodology as documented in WCAP-1 6406-P and the accompanying SE was utilized for the downstream effects analysis. Adverse blockage of downstream components has been evaluated by considering opening or gap sizes for components compared to the 1/16"-hole size in the sump strainer. Blockage and wear analysis results indicate no problems requiring additional modification to the plant. A summary of the downstream effects analysis is provided in section 3.m.2.

3.m.2 Downstream Evaluations.

Downstream effects evaluations were performed by a comprehensive,analysis that addressed components for blockage and wear in the affected systems with the exception of the HPI pump wear analysis and the cyclone separator and mechanical seal evaluations for the RBS, LPI, and HPI pumps. All components were found to have acceptable performance in accordance with the downstream effects analysis.

The comprehensive analysis addressed the impacts of wear on spray nozzles, orifices, heat exchanger tubes, throttled valves, and the LPI and RBS pumps (wear of the HPI pumps was performed in a separate analysis discussed below). This analysis also considered the potential for blockage due to any small clearances in the system. The debris loading for the downstream effects analysis used bounding inputs that exceeded the fiber and particulate loading determined by the debris generation calculation for the limiting break. The analysis used a strainer bypass value of 5% for the initial fiber pass and 100% for the subsequent passes, such that 5% of the fiber was assumed to remain in circulation. The strainer particulate bypass was modeled as 97%. The debris size for material in suspension passing through the strainer was modeled as remaining constant to conservatively address abrasive and erosive wear affects. A summary of the conclusions is as follows:

The calculated wear on the LPI and RBS pump's wear ring would result in minimal head loss at the end of the mission time (30 days).

The decay heat cooler tubing has sufficient thickness to withstand erosion.

The effect on system flow orifices was less than a 3% change in flow.

0 The effect on spray nozzles was less than the 10% change in flow rate acceptance criteria.

The effect on throttle valves was less than a 3% change in flow.

There was no impact on control instrumentation and root isolation valves due to debris.

Relief valves in the ECCS systems would not be prevented from performing their design functions due to debris in the water. The relief valves cannot reach their lift set points during the recirculation mode of operation.

The cyclone separator and mechanical seal evaluation for the ANO-1 LPI, HPI, and RBS pumps consisted of a comparative analysis of plant specific debris loads, cyclone separator flows and geometric design parameters against the Wyle Laboratories test report conducted for Exelon Power Generation. This analysis concluded that the ANO-1 cyclone separators were bounded by the debris and geometrical conditions in the tests. The performance of the cyclone.

separators was therefore determined to be qualified based on the debris laden test. Based on to 0CAN090801 Page 36 of 50 the ability of the cyclone separators to continue functioning to remove debris from the process water and to provide comparatively clean water to the mechanical seals, the function of the mechanical seals was also determined to be qualified for the post-LOCA operating conditions.

The debris comparison for cyclone separator operation conservatively used debris loads that exceeded those determined by the debris generation calculation for the most limiting break. All of the generated debris was conservatively assumed to transport to the screens and credit was not taken for settling. The debris concentration passing through the sump strainer was conservatively taken as 5% of the total fiber mass and 100% of the particulate mass (calcium-silicate insulation, latent particulate, and coatings). This provided a very conservative debris total for comparison to the tested debris loading. The ANO-1 total debris concentration remained significantly below the tested debris concentration for the cyclone separator tests

(<500 ppm ANO-1 debris concentration compared to 4150 ppm test concentration). Thus, the cyclone separator test provides a significantly bounding condition relative to those applicable to ANO-1.

The ANO-1 HPI pump is only operated in sump recirculation for a limited set of SBLOCA conditions where the RCS pressure remains above the LPI pump injection pressure. The HPI pump does not take suction directly from the sump, but is supplied by the LPI pump in "piggy back" mode of operation. The SBLOCA condition was not the most limiting case for sump strainer head loss, but since the HPI pumps could be in operation on sump recirculation after this event, the pumps were evaluated for downstream effects. Since the HPI pumps are multistage pumps, which have more involved analysis, the HPI pump wear modeling and analysis was performed by the pump OEM (Flowserve).

Detailed debris generation analysis for SBLOCA conditions was not performed. The pump wear analysis conservatively used the surge line break debris loading, which was a ten-inch pipe and Was considerably larger than the largest SBLOCA that would require HPI pump operation during sump recirculation. This break location also conservatively combined a calcium-silicate insulation piece on the surge line, a temp-mat fiber section from the RCS piping and increased latent particulate and coatings debris loading to ensure a conservatively bounding debris load was considered. The analysis conservatively assumes all of the generated debris was transported to the strainer and that 5% of the total fiber mass and 100% of the particulate mass passes through the sump strainer. A depletion coefficient was applied to the unqualified coatings outside the ZOI and all fibrous debris with the remaining debris assumed to remain entrained in the flowing fluid. The non-depleting debris concentration was determined to be

>175 ppm and the depleting concentration was <30 ppm. The wear to pump internals was evaluated to a maximum mission time of 30 days, which was very conservative relative to expected maximum HPI pump operating time on recirculation. The analysis showed that wear of the pump internals remained acceptable and did not significantly degrade hydraulic performance and was not substantial enough to negatively affect rotor stability.

3.m.3 Desicqn/Operational Changes No design changes or operations procedure changes were needed to address downstream effects.

to OCAN090801 Page 37 of 50 3.n Downstream Effects - Fuel and Vessel The objective of the downstream effects, fuel and vessel section is to evaluate the effects that debris carried downstream of the containment sump screen and into the reactor vessel has on core cooling.

1. Show that the in-vessel effects evaluation is consistent with, or bounded by, the industry generic guidance (WCAP-16793), as modified by NRC comments on that document. Provide a basis for any exceptions.

3.n.1 In-vessel Effects The in-vessel effects evaluation was performed in accordance with the guidance in WCAP-16793 and the initial NRC comments provided related to use of that document. This evaluation did not indicate problems with reactor core cooling. The fuel deposit analysis was performed per the WCAP-1 6793 spreadsheet with conservatively bounding inputs relative to the maximum debris loading conditions for the plant. This analysis determined that significant margin exists relative to the acceptance criteria, with total deposition thickness of <15 mils remaining well below the 50-mil maximum value and the maximum clad temperature of <3750F also remaining well below the 800°F acceptance criteria. The initial NRC comments provided for WCAP-1 6793 have been withdrawn and the WCAP is currently in revision, although the source of the revision is understood to be related to the fuel blockage analysis, not the fuel deposit methodology. Following the issuance of the revised guidance, further analysis could be necessary.

3.o Chemical Effects The objective of the chemical effects section is to evaluate the effect that chemical precipitates have on head loss and core cooling.

1. Provide a summary of evaluation results that show that chemical precipitates formed in the post-LOCA containment environment, either by themselves or combined with debris, do not deposit at the sump screen to the extent that an unacceptable head loss results, or deposit downstream of the sump screen to the extent that long-term core cooling is unacceptably impeded.

2. Content guidance for~chemical effects is provided in Enclosure 3 to a letter from the NRC to NEI dated September 27, 2007 (ADAMS Accession No. ML0726007425).

2.1 Sufficient 'Clean' Strainer Area

i. Those licensees performing a simplified chemical effects analysis should justify the use of this simplified approach by providing the amount of debris determined to reach the strainer, the amount of bare strainer area and how it was determined, and any additional information that is needed to show why a more detailed chemical effects analysis is not needed.

2.2 Debris Bed Formation

i. Licensees should discuss why the debris from the break location selected for plant-specific head loss testing with chemical precipitate yields the maximum head loss.

2.3 Plant Specific Materials and Buffers

i. Licensees should provide their assumptions (and basis for the assumptions) used to determine chemical effects loading: pH range, temperature profile, duration of containment spray, and materials expected to contribute to chemical effects.

2.4 Approach to Determine Chemical Source Term (Decision Point)

i. Licensees should identify the vendor who performed plant-specific chemical effects testing.

to OCAN090801 Page 38 of 50 2.5 Separate Effects Decision (Decision Point)

i. State which method of addressing plant-specific chemical effects is used.

2.6 AECL Model 2.7 WCAP Base Model

i. For licensees proceeding from block 7 to diamond 10 in the Figure 1 flow chart [in Enclosure 3 to a letter from the NRC to NEI dated September 27, 2007 (ADAMS Accession No. ML0726007425)], justify any deviations from the WCAP base model spreadsheet (i.e., any plant specific refinements) and describe how any exceptions to the base model spreadsheet affected the amount of chemical precipitate predicted.

ii. List the type (e.g., aluminum oxyhydroxide (AIOOH)) and amount of predicted plant-specific precipitates.

2.8 WCAP Refinements: State whether refinements to WCAP-16530-NP were utilized in the chemical effects analysis.

2.9 Solubility of Phosphates, Silicates and Aluminum Alloys

i. Licensees should clearly identify any refinements (plant-specific inputs) to the base WCAP-16530 model and justify why the plant-specific refinement is valid.

ii. For crediting inhibition of aluminum that is not submerged, licensees should provide the substantiation for the following: (1) the threshold concentration of silica or phosphate needed to passivate aluminum, (2) the time needed to reach a phosphate or silicate level in the pool that would result in aluminum passivation, and (3) the amount of containment spray time (following the achieved threshold of chemicals) before aluminum that is sprayed is assumed to be passivated.

iii.

For any attempts to credit solubility (including performing integrated testing), licensees should provide the technical basis that supports extrapolating solubility test data to plant-specific conditions. In addition, licensees should indicate why the overall chemical effects evaluation remains conservative when crediting solubility given that small amount of chemical precipitate can produce significant increases in head loss.

iv. Licensees should list the type (e.g., AIOOH) and amount of predicted plant specific precipitates.

2.10 Precipitate Generation (Decision Point)

i. State whether precipitates are formed by chemical injection into a flowing test loop or whether the precipitates are formed in a separate mixing tank.

2.11 Chemical Injection into the Loop

i. Licensees should provide the one-hour settled volume (e.g., 80 ml of 100 ml solution remained cloudy) for precipitate prepared with the same sequence as with the plant-specific, in-situ chemical injection.

ii. For plant-specific testing, the licensee should provide the amount of injected chemicals (e.g., aluminum), the percentage that precipitates, and the percentage that remains dissolved during testing.

iii. Licensees should indicate the amount of precipitate that was added to the test for the head loss of record (i.e., 100 percent 140 percent).

2.12 Pre-Mix in Tank to OCAN090801 Page 39 of 50

i. Licensees should discuss any exceptions taken to the procedure recommended for surrogate precipitate formation in WCAP-16530.

2.13 Technical Approach to Debris Transport (Decision Point)

i. State whether near-field settlement is credited or not.

2.14 Integrated Head Loss Test with Near-Field Settlement Credit

i. Licensees should provide the one-hour or two-hour precipitate settlement values measured within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of head loss testing.

ii. Licensees should provide a best estimate of the amount of surrogate chemical debris that settles away from the strainer during the test.

2.15 Head Loss Testing Without Near-Field Settlement Credit

i. Licensees should provide an estimate of the amount of debris and precipitate that remains on the tank/flume floor at the conclusion of the test and justify why the settlement is acceptable.

ii. Licensees should provide the one-hour or two-hour precipitate settlement values measured and the timing of the measurement relative to the start of head loss testing (e.g., within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months ).

2.16 Test Termination Criteria

i. Provide the test termination criteria.

2.17 Data Analysis:

i. Licensees should provide a copy of the pressure drop curve(s) as a function of time for the testing of record.

ii. Licensees should explain any extrapolation methods used for data analysis.

2.18 Integral Generation (Alion) 2.19 Tank ScalinglBed Formation

i. Explain how scaling factors for the test facilities are representative or conservative relative to plant-specific values.

ii. Explain how bed formation is representative of that expected for the size of materials and debris that is formed in the plant-specific evaluation.

2.20 Tank Transport

i. Explain how the transport of chemicals and debris in the testing facility is representative or conservative with regard to the expected flow and transport in the plant-specific conditions.

2.21 30-Day Integrated Head Loss Test

i. Licensees should provide the plant-specific test conditions and the basis for why these test conditions and test results provide for a conservative chemical effects evaluation.

ii. Licensees should provide a copy of the pressure drop curve(s) as a function of time for the testing of record.

2.22 Data Analysis Bump-Up Factor

i. Licensees should provide the details and the technical basis that show why the bump-up factor from the particular debris bed in the test is appropriate for application to other debris beds.

3.o.1 Evaluation Results The ANO-1 approach to chemical precipitate analysis related to strainer head loss was two-fold.

Strainer qualification testing was performed at a test flume by Fauske and Associates using strainer cartridges fabricated by CCI. The strainer cartridges used for strainer qualification testing were identical to those installed at ANO-1. The strainer qualification testing determined the combined maximum sump strainer head loss from both chemical precipitates and debris to 0CAN090801 Page 40 of 50 (insulation and coating). The strainer qualification testing concluded that the maximum head loss with both chemical effects and debris was <8'. Strainer head loss testing is discussed in detail in section 3.f.

Testing has also been conducted by Westinghouse in an autoclave device to characterize the expected time periods that potential chemical precipitates may develop given a plant-specific debris mix. The autoclave tests provided supporting data to conclude that chemical effects precipitates were not applicable to ANO-1 during the period of elevated sump temperatures (197°F or above) when strainer head loss was limited by NPSH margin.

The results of the combined debris and chemical precipitate tests indicate that for two-train full flow, unacceptably high head loss may develop if all of the chemical loading was assumed to be present in the early accident response period when sump temperatures are elevated. However, the autoclave test results show that the chemical precipitates occur later in the accident response period when sump temperatures are lower.

The occurrence of chemical precipitates after the sump temperatures are lowered was significant since increased NPSH margin would be present due to the vapor pressure difference between the sub-cooled water temperature and reactor building pressure. Since credit was not taken for increased building pressure following a LOCA when determining available NPSH, the vapor pressure margin was assumed to be zero when sump temperatures are at or above 208.40F (the saturation temperature at the minimum TS-allowed reactor building pressure of 13.7 psia). Below this temperature the difference in vapor pressure adds substantial NPSH margin, such that the structural stress design limit, which exceeds 10.5 ft of differential pressure, becomes the strainer's head loss limit.

3.o.2.1.i Sufficient 'Clean' Strainer Area This is not applicable since simplified chemical effects analysis was not performed.

3.o.2.2.i Debris Bed Formation Due to the low available fiber source for ANO-1, only thin-bed insulation coverage of the screen was possible, even considering the most conservative application of 100%

disintegration/erosion of fiber into fines with 100% transport of those fines to the screen surface area. Therefore, the debris case selected for chemical effects head loss testing was the maximum debris load case. ANO-1 conducted a series of strainer head loss tests, including a number of sensitivity tests, to determine the head loss response to variations in the debris loading with and without chemical precipitates. The testing indicated that thin-bed conditions can be established with significantly thinner layers of fiber than the nominal 1/8" layer originally defined for this condition. However, the testing also indicated that the "ultra-thin" fiber beds do not produce the maximum head loss conditions compared to slightly thicker fiber layers (although still in the thin-bed range), primarily due to breaching of the debris bed by blow-holes or jetting through the thin layer of insulation fiber. Thus, based on the limited quantities of non-RMI insulation materials available, the maximum debris load was conservative for chemical effects strainer head loss testing of ANO-1.

As noted previously in section 3.f.5, actual tested debris loads exceeded those predicted by the debris generation calculation to ensure margin existed for possible future minor material changes, discovery of previously unevaluated trace amounts of insulation, or similar conditions.

to OCAN090801 Page 41 of 50 3.o.2.3.i Plant-Specific Materials and Buffers ANO-1 uses NaOH as the pH buffer. The chemical precipitates predicted by the WCAP-16530 models where NaOH was used as a buffer were associated with aluminum compounds.

Therefore, chemical effects at ANO-1 were limited to aluminum-based compounds.

The pH evaluated for ANO-1 chemical effects was from a maximum of 9.0 to a minimum of 7.0.

Aluminum corrosion has a significant dependency on pH, with corrosion rates increasing as pH increases. Aluminum solubility decreases significantly as pH is lowered. Temperatures produce similar impacts on aluminum corrosion (higher at high temperatures) and solubility (lower at low temperatures). Since the WCAP-1 6530 model does not assume any solubility of aluminum it was conservatively modeled with maximum pH and the maximum temperature profile. These inputs produce the largest amount of predicted aluminum corrosion and therefore the greatest amount of precipitates.

The integrated tests run in the autoclave used maximum pH and temperature profiles to maximize aluminum corrosion. To account for lower aluminumsolubility at lower pH conditions, separate autoclave runs were conducted with a starting pH of 9 and a pH of 8. Samples drawn from each were tested at the starting pH and with pH buffered down by -0.5 and -1.0 step reductions. This provided a spectrum of data points for pH values ranging from 9.0 to 7.0. The potential variation in sump pH was almost entirely based on starting condition assumptions (i.e.,

water volumes, NaOH volumes and concentrations, boron concentrations, etc.) that affect the initial sump pH, with only a very small (<0.25) reduction from the starting pH over the course of the mission time due to acids generated post-LOCA. Therefore, the autoclave test has conservatively accounted for the impact of pH on aluminum solubility in the test samples. The impact of reduced temperature on solubility was addressed by use of final temperatures near ambient or room conditions (approximately 750F to 800F).

Samples were drawn for chemical analysis and filtration testing at time periods of one, two, three, five, and seven days for the seven-day tests. Earlier autoclave tests run for 30 days, included samples at three and four weeks. The 30-day tests indicated that the aluminum corrosion was occurring early in the test period at elevated temperatures. Changes that occurred at lower temperatures were primarily associated with precipitation. Later tests were subsequently shortened to seven days. The sump temperatures at the end of seven days were substantially reduced (i.e., approximately 150°F based on single-train response). Therefore, the autoclave temperature profile was adjusted to ramp temperatures down to approximately 80°F over the last two days of the seven-day tests to provide a somewhat gradual temperature reduction, but significantly accelerated compared to the three-plus weeks associated with the 30-day tests.

The vast majority of aluminum present in the reactor building is not submerged; therefore, the corrosion mechanism is exposure to RBS. The model conservatively assumes 30-day operation of the spray system, even though guidance is present in the ANO-1 emergency operating procedures for securing RBS, and the conditions to support securing building spray should be reached well before 30 days.

3.o.2.4.i Chemical Source Term Plant-specific chemical testing was performed by Fauske and Associates for field testing of strainer head.loss with chemical precipitates and debris. Plant-specific chemical testing was conducted by Westinghouse for autoclave analysis of potential chemical precipitates.

Attachment I to 0CAN090801 Page 42 of 50 3.o.2.5.i Separate Effects Decision The ANO-1 autoclave chemical effects tests conducted by Westinghouse were an integrated test that included various debris source term materials evaluated together. See section 3.o.1.

3.o.2.6 AECL Model The AECL model was not used.

3.o.2.7.i WCAP Base Model Deviation The base model of WCAP-16530 was used to predict the amount of chemical precipitate produced. As noted in section 3.o.1, the results of autoclave testing were used to determine the timing with regards to sump temperature of the chemical precipitate loading. Strainer testing was conducted to determine the head loss impact associated with the full WCAP-16530 predicted chemical precipitate loading. The autoclave test results establish that the chemical loading does not occur early in the accident response period when sump temperatures are elevated (i.e., 1970F or higher) and when pump NPSH margin was the limiting factor for strainer head loss. The chemical precipitates instead come out of solution after sump temperatures have been sub-cooled. The strainer head loss associated with the WCAP-16530 chemicals was compared against the strainer structural design limit (>10.5 ft). The strainer structural margin was the limiting factor for strainer head loss after sump temperatures are reduced below 1970F.

Due to difficulty meeting the settling criteria for AIOOH material, the flume testing was conducted with only NAS materials. Based on test results and bench-top comparison tests of the two precipitates, this change did not affect the final results.

3.o.2.7.ii WCAP Base Model Precipitates Predicted plant precipitates using the WCAP-16530 base model were approximately:

Total Aluminum Released/Corroded:

<45 kg NAS:

<100 kg AIOOH:

<75 kg 3.o.2.8.i WCAP Refinements The refinements provided in the WCAP were not utilized in the chemical effects analysis. The aluminum solubility refinement discussed in section 3.o.2.9.i was based on autoclave testing performed for ANO, versus the published WCAP refinements.

3.o.2.9.i Solubility Refinements In addition to the strainer head loss tests, testing was also conducted by Westinghouse to better understand the potential chemical precipitates that may develop at ANO-1 following a LOCA. A series of autoclave tests were conducted that included equivalent amounts of aluminum and other debris in a test chamber that replicated the most limiting temperature and pH profile for post-LOCA conditions. The tests were conducted for extended periods, with earlier tests run for the full 30-day mission time and later tests run for seven days. Samples were drawn from the autoclave water for analysis and testing to determine the chemicals present and changes in filterability that would indicate the formation of chemical precipitates. Test results were consistent with the expected behavior of aluminum in solution, with aluminum solubility decreasing with decreasing temperature as well as with decreasing pH. The later tests included a "cold finger" which was used to establish that fouling of heat exchanger tubes (i.e., decay heat cooler tubes) or similar cold surfaces would not occur due to chemical precipitates. The autoclave test results were not used to change the amount or type of chemical precipitates formed relative to the WCAP-1 6530 model, but were used to establish that the chemical precipitates were not present at elevated sump temperatures due to higher aluminum solubility.

The WCAP-16530 model did not credit any threshold for aluminum solubility.

to oCAN090801 Page 43 of 50 The timing of the chemical precipitate formation was the refinement applied, which was based on testing conducted for ANO site-specific conditions. The formation of precipitates after the sump temperature has decreased was a more realistic condition that was supported by integrated test results. This shift in precipitate formation timing was significant due to the additional NPSH margin that exists with a sub-cooled sump.

3.o.2.9.ii Creditinq Aluminum Inhibition Aluminum inhibition was not credited. The calcium-silicate insulation volumes potentially impacted by a LBLOCA combined with other potential silica sources were insufficient to reach the concentrations needed to support aluminum passivation. No credit was taken for reductions in aluminum corrosion rates or total, corroded mass.

3.o.2.9.iii Solubility Credit The WCAP-16530 was noted in the NRC safety evaluation as being conservative due to not crediting aluminum solubility. This conservatism was credited as the basis for accepting WCAP-1 6530 methodology Versus pursuing more rigorous testing and analysis. Therefore, it was recognized that taking exceptions to or deviations from a generic application of WCAP-1 6530 for chemical effects analysis requires providing a holistic or composite analysis of the treatment of chemical effects, with an explanation of why the net approach remains conservative.

The overall chemical effects evaluation remains significantly conservative due to a large number of stacked conservative inputs that form the basis for the credited head loss as outlined previously in section 3.f.8. For a plant such as ANO-1 with relatively small potential sources of fiber and particulate debris loading, several of the conservative inputs could by themselves reduce head loss to clean screen values.

The autoclave testing results show that significant margin also exists relative to the temperature threshold of 197 0F at which strainer head loss was limited by the sump strainer structural limits versus the NPSH margin. The autoclave tests included a bounding high aluminum input case originally intended to force chemical precipitates. This case included a significantly' higher thin aluminum input of over 8000 ft2 and >250 Ibm equivalent values. The WCAP-16530 model predicted total aluminum release for this case as >120 kg. This represents an increase of over 75 kg of aluminum above the base aluminum case or approximately three times the condition representative of the aluminum content in ANO-1 per the WCAP model. The autoclave samples from the high aluminum test showed elemental aluminum content that was higher than the base autoclave test by approximately a factor of four. The high aluminum test autoclave samples did not have increased filtration times for the samples taken at 2050F, 1800F, or 1570F, with the sample taken at 130°F the first to show slightly higher filtration times, indicating that chemical precipitates were not present at the higher temperatures even with the significantly higher aluminum loading. The high aluminum autoclave samples did not show substantial increases in filtration time-until the 82°F temperature sample was tested. When temperature and pH were lowered the high aluminum autoclave samples produced rather dramatic increases in filtration times. The series of autoclave tests provides confidence that there was significant margin with respect to temperature solubility threshold being credited as the basis for comparing strainer.

head loss with chemical effects to structural limits versus pump NPSH limits.

3.o.2.9.iv Predicted Plant-Specific Precipitates Testing was performed with the precipitate quantity associated with the WCAP-1 6530 base model noted in section 3.o.2.7.ii.

to OCAN090801 Page 44 of 50 3.o.2.10.i Precipitate Generation Precipitates for strainer head loss testing were formed outside the test facility loop in accordance with guidance of the WCAP documents and adjusted settling criteria defined by the SE.

3.o.2.1 1.i Chemical Injection Precipitate Volume This is not applicable since plant-specific chemical injection tests were not conducted versus preparation per the WCAP-1 6530 guidance.

3.o.2.11.ii Iniected Chemicals This is not applicable since plant-specific chemical injection tests were not conducted versus preparation per WCAP-1 6530 guidance.

3.o.2.11.iii Added Precipitate This is not applicable since plant specific chemical injection tests were not conducted versus preparation per the WCAP-16530 guidance.

3.o.2.12.i Pre-Mix in Tank No exceptions were taken to the procedure recommended for surrogate precipitate formation in WCAP-1 6530.

Due to difficulties in producing AIOOH chemical precipitate at the Fauske test facility that consistently met the settling criteria, the tests were conducted with only NAS chemical surrogates. Both of the aluminum chemical surrogates were reported to have similar adverse head loss characteristics in the SER for WCAP-1 6530 and an excess of NAS was added to the flume to determine a bounding head loss. After approximately 55-60% of the tested NAS chemical precipitate had been added, the strainer head-loss did not increase further. Since the equivalent amount of NAS added to the test flume exceeded the amount predicted by the WCAP-16530 model by more than a factor of two, and the strainer head loss peaked after approximately 60% of the chemical precipitate was added, no further chemical additions were deemed necessary to determine a bounding effect from chemical precipitates. Five additional batches of chemical precipitate were added and the test run for approximately 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months after the peak head loss value had been reached, with stirring used periodically to ensure head loss was not limited by settled materials. The amount of aluminum released by corrosion predicted by the WCAP-1 6530 model and the associated chemical precipitates from the model were as follows:

Base Aluminum Inventory Aluminum Released/Corroded (kg)

<45 NAS Precipitate (kg):

<100 AIOOH Precipitate (kg):

<75 The chemical effects strainer head loss testing included an amount of NAS equivalent to

>200 kg of NAS chemical precipitates in the plant.

3.o.2.13.i Near-Field Settlement Near-field settling in the test flume was not credited. Stirring of the test flume water was performed as-needed to achieve transport of the added debris into the strainer cartridges.

Acceptance was based on visual observation through the clear panels of the flume to confirm that only trace amounts of particulates or isolated paint chips remained outside the strainer.

Stirring was also used with the chemical precipitates. However, as increased chemical precipitate was added to the test flume a settled layer of the chemical precipitate would reform in the flume after stirring. Based on the head loss not changing in response to multiple stirring to OCAN090801 Page 45 of 50 periods when a large portion of the chemical precipitates were in the flume, the effect of this settling of chemical precipitates was determined not to adversely impact the maximum head loss indicated. Chemical precipitates were also observed on horizontal surface downstream of the strainer, indicating that at least a portion of the material was passing through the strainer.

3.o.2.14.i Near-Field Settlement Values Near-field settling was not credited.

3.o.2.14.ii Surroqate Chemical Debris Settlement Near-field settlement was not credited.

3.o.2.15.i Debris/Precipitate Without Near-Field Settlement Credit See section 3.o.2.13.i.

3.o.2.15.ii Precipitate Values Without Near-Field Settlement Credit The one-hour settled volumes for NAS precipitates were 8.5 to 9 ml for a 10 ml sample which remained cloudy. Testing was performed within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of precipitate mixing with preparation in accordance with WCAP-16530.

3.o.2.16.i Test Termination Criteria The peak head loss reading was reached well prior to the end of the test (72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months earlier) and was followed by additional chemical precipitate and stirring that did not further increase peak strainer head loss. The peak strainer head loss values were used as the test result.

Test conditions for the integrated test included the full debris bed loading predicted by the debris generation calculation. Flows were evaluated at bounding maximum values for two-train operation. Chemical precipitate loading equal to greater than 100% of the total mass of precipitates was tested, although NAS was used to represent the chemical effects. The base WCAP-16530 model predicts that 55% of the precipitates would be NAS, and 45% would be AIOOH. The test results did not show an increase in maximum head loss after approximately 60% of the chemicals were added in the test flume, with subsequent chemical additions resulting in either no change or a slight decrease in head loss. Ample excess precipitate was visually evident in the test flume, since it could be observed to settle, but stirring did not result in any change to the peak measured head loss. Comparison of bench-top filter time tests was also performed between the two types of aluminum precipitates. Based on that comparison, the introduction of excess precipitate quantity, and the lack of detrimental results from additional chemical precipitates, the use of a single chemical effects surrogate was acceptable.

The test duration was not 30 days; however, the test did bound a maximum head loss value, with continued operation resulting in a decrease rather than an increase in head loss. The chemical precipitates were also not added in one batch or over one day. Due to the relatively large amount of chemical precipitate predicted by the WCAP-16530 base model, preparation of 100% of the chemical materials was not practical in a short time period. Autoclave test results indicated that most of the precipitate would not be expected to form until sump temperatures began to cool, thus a more gradual addition was considered more prototypic of plant conditions.

Chemical precipitates were added in 5% to 10% increments of the total loading. Early additions provided rapid and significant head loss increases, although the last significant increase occurred when the concentration was raised from 30% to 40% of the total and a peak value was reached between 50% and 60% of the total, with slightly declining head loss afterwards. The test facility loop was run for 14 days during the integrated chemical precipitate testing.

Attachment I to OCAN090801 Page 46 of 50 The test results provide bounding and conservative values for potential strainer head losses both with and without chemical effects. This was based on conservative application of each of the test inputs. An extensive array of tests were conducted to provide an accurate understanding of the head loss characteristics of various types and quantities of debris as well as of the chemical precipitates that may form in a post-LOCA environment. The combined effects of these materials were tested in a conservative manner with the most limiting results used for acceptance.

3.o.2.17.i Pressure Drop Curve as a Function of Time Pressure drop curves from the strainer qualification head loss test are provided below along with an associated data table.

Figure 3.o.2.17.i-1 Head Loss History for strainer qualification 2,

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Time, hr Figure 3.o.2.17.i-2 Flow Rate History for strainer qualification to OCAN090801 Page 47 of 50 2 5 0I I

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2.--.::25.0 30 350 T imen, hr Table 3.o.2.17.i-1 Data Point for Strainer Qualification Testing Time (sec)

Head Loss (psid)

Flow Rate (gpm)

Comments 558 1.90E-03 221.31 a) 1.18 lbs HDFG added 1517 2.40E-03 215.95 b) 0.60 lbs Transco Mat added 2177 2.OOE-04 229.57 c) 0.2009 lbs Thermal Wrap added 3017 2.30E-03 230.68 d) 0.5 lbs Latent Fiber added 3797 6.30E-03 215.6-e) 4.5 lbs calcium-silicate added Final head loss value after addition of calcium-silicate and before 6343 3.47E-02 230.6 addition of silicon-carbide 6767 1.59E-01 226.79 f) 17 lbs silicon-carbide added 7577 2.39E-01 218.63 g) one lb paint chips added 13020 2.89E-01 219.39 Head loss value before stirring 13187 3.67E-01 215.27 Head loss value after stirring 20866 3.21 E-01 213.72 Head loss value before stirring 21199 3.86E-01 216.86 Head loss value after stirring 65768 3.02E-01 220.87 Head loss value before stirring 66436 3.86E-01 214.51 Head loss value after stirring 73638 3.63E-01 217.83 h) 0.485 lbs chemical (NAS) added 76216 9.44 E-0 1 215.63 i) 0.485 lbs chemical (NAS) added 78088 1.57E+00 213.18 j) 0.485 lbs chemical (NAS) added to OCAN090801 Page 48 of 50 78788 102492 250369 250577 425297 440896 513985 514767 514850 515867 515983 517050 517183 518250 518400 591540 611280 611949 858600 870840 874770 938880 949680 960120 1035720 1042920 1113948 1128600 1.71E+00 1.42E+00 1.54E+00 4.09E-01 7.43E-01 7.77E-01 1.32E+00 1.19E+00 1.62E+00 1.39E+00 1.89E+00 1.67E+00 1.88E+00 1.78E+00 4.97E-01 5.36E-01 6.34E-01 1.27E+00 1.24E+00 1.32E+00 1.35E+00 1.34E+00 1.36E+00 1.33E+00 1.35E+00 1.30E+00 1.32E+00 1.26E+00 214.72 218.81 220.32 114.54 111.21 108.87 140.28 140.45 175.22 174.67 210.7 210.59 224.35 225.98 119 117.66 115.19 104.37 110.89 116.68 107.79 104.5 101.27 111.61 109.23 110.88 111.15 107.97 131.58 144.74 145.39 Maximum head loss after the initial NAS addition Minimum head loss during the head loss recovery phase after the initial NAS addition Head loss at 221 gpm prior to flow adjustment to 110 gpm Minimum head loss after flow adjusted from 221 gpm to 110 gpm k) 0.485 lbs Chemical (NAS) added

1) 0.485 lbs Chemical (NAS) added Head loss after flow adjusted from 110 gpm to 140 gpm Head loss at 140 gpm prior to flow adjustment to 170 gpm Head loss after flow adjusted from 140 gpm to 170 gpm Head loss at 170 gpm prior to flow adjustment to 210 gpm Head loss after flow adjusted from 170 gpm to 210 gpm Head loss at 210 gpm prior to flow adjustment to 221 gpm Head loss after flow adjusted from 210 gpm to 221 gpm Head loss at 221 gpm prior to flow adjustment to 110 gpm Head loss after flow adjusted from 221 gpm to 110 gpm m) 0.485 lbs chemical (NAS) added n) 0.970 lbs chemical (NAS) added Maximum head loss achieved after additional NAS addition

0) 0.485 lbs chemical (NAS) added p) 0.485 lbs chemical (NAS) added Maximum head loss achieved after additional NAS addition q) 0.485 lbs chemical (NAS) added r) 0.485 lbs chemical (NAS) added s) 0.485 lbs chemical (NAS) added t) 0.485 lbs chemical (NAS) added u) 0.970 lbs chemical (NAS) added v) 0.970 lbs chemical (NAS) added w) 0.970 lbs chemical (NAS) added Head loss after flow adjusted from 110 gpm to 130 gpm Head loss after flow adjusted from 130 gpm to 140 gpm Head loss at 140 gpm prior to flow adjustment to 110 gpm 1191711 1.78E+00 1194524 1.98E+00 1195657 1.93E+00 to OCAN090801 Page 49 of 50 Head loss at 110 gpm prior to flow 1196259 1.17E+00 113.16 adjustment to 90 gpm Head loss at 90 gpm prior to flow 1196727 8.56E-01 94.41 adjustment to 70 gpm Head loss at 70 gpm prior to flow 1196928 5.55E-01 67.11 adjustment to 110 gpm 1207761 1.21E+00 113.16 Head loss just prior to system shutdown 3.o.2.17.ii Extrapolation Methods Due to. limitations of the test facility for elevated head loss measurement, the testing could not all be conducted at maximum flow conditions. The test facility was configured with a set of CCI strainer cartridges attached to a vertical divider plate in a test tank. The head loss across the strainer results in a physical elevation difference across the divider plate. The maximum head loss was limited by the recirculation pump suction pipe needing to remain covered., To maintain the head loss within the limits of the test facility, flow was lowered when level behind the strainer began to approach the suction pipe.

After the flow reduction, chemical precipitate continued to be added in 5% to 10% increments until full chemical loading was complete. Head loss response to flow changes was checked at two subsequent times after the flow reduction, once with 25% of chemicals added and then after 100% of the chemicals were added. The measured head loss continued to respond to flow changes. Flow was maintained at approximately 50% of maximum values (equivalent to one train in service) for the later debris additions and the largest measured head loss under these conditions was approximately 1.4 psid or 3.2 ft.

The measured head Ioss was extrapolated to a maximum head loss at maximum flow by comparison of the strainer head loss response to the flow adjustments. The strainer head loss response to flow increase at 25% of the tested chemical load was approximately directly proportional. At 100% of the tested chemical loading the head loss response was slightly greater than a 1:1 proportion, although the range of flowincrease was restricted to about 30%

due to reaching the test facility measurement limits at that flow increase. While it was likely that the debris bed would have reached a maximum head loss limit caused by perforations (i.e.,

blow holes or jetting conditions) before this trend could be extrapolated up todoubling the flow, it was conservative to assume the rate of increase would be sustained.

The final head loss was projected as slightly less than eight feet at two-train full flow conditions with chemical loading. Since the peak chemical loading was expected to occur when temperatures are-lowered to near ambient, no viscosity corrections were applicable. The application of maximum two-train flow for this head loss condition was conservative since it is very likely that sump recirculation flows would be reduced prior to the point of sump temperature conditions being substantially sub-cooled due to securing of building spray flow and/or the second train of LPI flow prior to reaching this phase of accident recovery.

3.o.2.18.i Integral Generation (Alion)

The Alion methodology was not used.

3.o.2.19.i Scaling Factors The'Alion integral methodology was not used. See Section 3.f.4 for discussion of test facility scaling.

to OCAN090801 Page 50 of 50 3.o.2.19.ii Bed Formation The Alion integral methodology was not used. The debris bed formation is described in sections 3.f and 3.o.2.2.i.

3.o.2.20.i Tank Transport The Alion integral methodology was not used.

3.o.2.21.i 30-Day Integrated Head Loss Test Conditions The Alion integral methodology was not used.

3.o.2.21.ii Pressure Drop Curve as a Function of Time The Alion integral methodology was not used.,

3.o.2.22.i Bump-Up Factor The Alion integral methodology was not used.

3.p Licensing Basis The objective of the licensing basis section is to provide information regarding any changes to the plant licensing basis due to the sump evaluation or plant modifications, Provide the information requested in GL 2004-02, "Requested Information," Item 2.(e) regarding changes to the plant licensing basis. That is, provide a general description of and planned schedule for any changes to the plant licensing bases resulting from any analysis or plant modifications made to ensure compliance with the regulatory requirements listed in the Applicable Regulatory Requirements section of this generic letter. Any licensing actions or exemption requests needed to support changes to the plant licensing basis should be included. The effective date for changes to the licensing basis should be specified. This date should correspond to that specified in the 1 OCFR50.59 evaluation for the change to the licensing basis.

The plant modifications at ANO-1 implemented in response to GL 2004-02 that required changes to the licensing basis are listed below with the corresponding dates for licensing basis changes:

ER-ANO-2001-1205-001: This modification revised the ANO-1 SAR to describe the upgraded sump strainer, the deletion of the sump vortex suppressor, and relocation of sump level instrumentation. The sump strainer modification was installed in spring 2007 during the 1 R20 refueling outage.

EC-2245: This modification reduced the NaOH tank concentration to values within the existing range specified in the ANO-1 TSs in December 2007. The new NaOH concentration range is being administratively controlled until the license amendment request dated July 30, 2008 (1CAN070801), is approved.

EC-2243: This engineering change revised the ANO-1 design basis for ECCS/RBS recirculation to show that new regulatory requirements resulting from GL 2004-02 are satisfied. This change, approved by Entergy on August 12, 2008, also revised the ANO-1 SAR to describe changes to ECCS and RBS NPSH analyses resulting from GL 2004-02 requirements.

0CAN090801 ANO-2 Supplemental Response to OCAN090801 Page 1 of 55 ANO-2 Supplemental Response

1. Overall Compliance Provide information requested in Generic Letter GL 2004-02, "Requested Information,"

Item 2(a) regarding compliance with regulations. That is, provide confirmation that the emergency core cooling system (ECCS) and containment spray system (CSS) recirculation functions under debris loading conditions are or will be in compliance with the regulatory requirements listed in the Applicable Regulatory Requirements section of this GL. This submittal should address the configuration of the plant that will exist once all modifications required for regulatory compliance have been made and the licensing basis has been updated to reflect the results of the analysis.

By letter dated April 30, 2008 (0CNA040804), the NRC approved a request for an extension of the completion date of August 15, 2008, with the final supplemental response due by September 15, 2008. The design change package (EC-2244) updating the ANO-2 design basis associated with GSI-191 resolution and GL 2004-02 compliance was approved August 14, 2008, by Entergy, along with an associated ANO-2 Safety Analysis Report (SAR) revision provided to licensing. This submittal provides the final supplemental response for compliance with the regulatory requirements in GL 2004-02.

2. General Description of and Schedule for Corrective Actions Provide a general description of actions taken or planned, and dates for each. For actions planned beyond December 31, 2007, reference approved extension requests or explain how regulatory requirements will be met as per "Requested Information" Item 2(b). That is, provide a general description of and implementation schedule for all corrective actions, including any plant modifications, that you identified while responding to this GL.

During the fall 2006 refueling outage (2R18), the original sump screen (approximate area of 150 ft2) was replaced with a new engineered strainer. The replacement strainer is a modular design and has a surface area of approximately 4837. ft2.

The following modifications were implemented during spring 2008 refueling outage (2R19):

Chemical buffer change from trisodium-phosphate (TSP) to sodium-tetraborate (NaTB) to support chemical effects analysis Fiber insulation replacement Calcium-silicate insulation removal Calcium-silicate insulation banding to reduce the zone-of-influence (ZOI)

Sump plenum modification to increase the structural qualification limit Refueling canal drain strainer installation Reactor cavity drain check valve screen removal Pipe drain line modification to terminate outside the sump strainer to OCAN090801 Page 2 of 55

3. Specific Information Regarding Methodology for Demonstrating Compliance 3.a Break Selection The objective of the break selection process is to identify the break size and location that present the greatest challenge to post-accident sump performance.

1. Describe and provide the basis for the break selection criteria used in the evaluation.

2. State whether secondary line breaks were considered in the evaluation (e.g., main steam and feedwater lines) and briefly explain why or why not.

3. Discuss the basis for reaching the conclusion that the break size(s) and locations chosen present the greatest challenge to post-accident sump performance.

3.a.1 Baseline Break Selection The ANO-2 nuclear steam supply system (NSSS) is a Combustion Engineering two-loop pressurized water reactor (PWR). The system consists of one reactor vessel, two steam generators (SGs), four reactor coolant pumps (RCPs), one pressurizer, and the reactor coolant system (RCS) piping. The NSSS is located inside a bioshield (D-ring) consisting of two SG cavities.and one reactor cavity. Each SG cavity houses one SG and two RCPs. Additionally, the south SG cavity houses the pressurizer. The outer walls of the D-ring extend from the containment base elevation (El.) 336'-6, to El. 426'-6". The ANO-2 sump is located on the south azimuth of containment outside-the D-ring.

The break selection methodology described in Nuclear Energy Institute (NEI) 04-07 was used to determine the most limiting breaks with regard to maximum debris generation. Following the initial debris generation analysis, a series of strainer head loss sensitivity tests were run. Based on the results of those tests, additional modifications were implemented in the spring 2008 refueling outage. Strainer head loss margin was achieved by reducing the debris loading through removal of insulation from some lines, changing insulation types, and banding the lagging on numerous lines to reduce the ZOI. The break analysis was revised to reflect the outage modifications, which required additional checks of the break locations on the hot and cold leg piping in both cavities and in the surge line to ensure that the maximum debris generation locations were identified for the smaller ZOls from banding calcium-silicate insulation. The final strainer head loss qualification tests were then conducted to reflect the reduced debris loading. The following breaks were found to be the four most limiting with regard to maximum debris generation as listed in Table 3.a.1-1 and shown in Figure 3.a.1-1.

Table 3.a.1-1 Postulated Break Locations Break Break ID Location Description 1SG Cavity Name (inches)

$1 42 Hot Leg, A SG South S2

42 Hot Leg, B SG North S4 10.126 Pressurizer Surge Line South S6 30 Cold Leg, A RCP South to OCAN090801 Page 3 of 55 Pressurizer Figure 3.a.1-1 ANO-2 Break Locations (S5 shown at original location versus at D-RCP Cold Leg) 3.a.2 Secondary Line Breaks Feedwater and main steam line breaks do not require the CSS or ECCS to operate in recirculation; therefore, the piping associated with these systems was not evaluated.

3.a.3 Size and Location Conclusion The break selections have attempted to maximize the various available debris types. Since no single break produces the largest quantity of all debris sources, different breaks were evaluated to ensure that the fiber and particulate loads were maximized, Since these debris types were found to produce the most limiting strainer head loss.

The hot leg is the largest line (42-inch ID) within the SG cavity and produces the largest ZOI.

Break S1 in the south cavity with the pressurizer results in the most coating debris. Break S6, the A-Cold Leg break, produces the maximum amount of calcium-silicate insulation debris.

Neither Break S3 nor Break S6 produces the maximum fiber debris due to the distance between the break and the pressurizer.

The cold leg has a smaller diameter (30-inch ID) than the hot leg and produces a smaller ZOI.

However, break s6 in the cold leg suction from SG-A to RCP-A could direct flow out of the D-ring along a flow path to the containment sump. In addition, the RCP-A cold leg is close to the pressurizer where a source of fiber insulation exists and near the regenerative heat exchanger where additional calcium-silicate insulated lines are located.

Thermal wrap blanket fiber insulation is located On the top and bottom heads of the pressurizer and around the inside of the pressurizer skirt. Due to the shield wall around the lower pressurizer, the floor slab below the pressurizer, and the distance from the RCS hot leg or cold legs, this insulation is not a debris source for breaks in those lines. Hence, a break was postulated at the surge line near the connection to the pressurizer to provide the most limiting quantity of fiber insulation.

to 0CAN090801 Page 4 of 55 3.b Debris Generation/ZOI (excluding coatings)

The objective of the debris generation/ZOI process is to determine, for each postulated break location: (1) the zone within which the break jet forces would be sufficient to damage materials and create debris; and (2) the amount of debris generated by the break jet forces.

1. Describe the methodology used to determine the ZOls for generating debris.

Identify which debris analyses used approved methodology default values. For debris with ZOls not defined in the guidance report/safety evaluation (SE), or if using other than default values, discuss method(s) used to determine ZOI and the basis for each.

2. Provide destruction ZOls and the basis for the ZOls for each applicable debris constituent.

3. Identify if destruction testing was conducted to determine ZOls. If such testing has not been previously submitted to the NRC for review or information, describe the test procedure and results with reference to the test report(s).

4. Provide the quantity of each debris type generated for each break location evaluated. If more than four break locations were evaluated, provide data only for the four most limiting locations.

5. Provide total surface area of all signs, placards, tags, tape, and similar miscellaneous materials in containment.

3.b.1 ZOI Methodology The ZOI radii for applicable insulation materials were in accordance with NEI 04-07. When ZOls for identified materials or the installed configuration was not provided in NEI 04-07, ZOI destructive testing was performed or conservative bounding ZOls were applied based on similarities with other materials. ZOIs that were not taken directly from the guidance document are listed below:

" The ZOI for calcium-silicate insulation listed in NEI 04-07 was based upon tests performed with banded lagging. Portions of the lagging at ANO are fastened with sheet metal screws instead of banding which was considered a potentially non-conservative variation from the ZOI for calcium-silicate with banded lagging. Westinghouse performed jet impingement testing at Wyle Labs test facility in order to establish a ZOI consistent with the methodologies documented in NEI 04-07 for calcium-silicate insulation covered with screwed rather than banded lagging. A test conducted at an equivalent distance of a 25D ZOI was used to conservatively establish the ZOI-for this configuration.

There is not guidance in NEI 04-07 regarding the ZOI for Transco Thermal-Wrap blankets.

ZOI destructive testing was utilized to determine a ZOI of 7D for Transco Thermal-Wrap blankets.

Ceramic fiber insulation that was originally used at elbows, hangers and fittings on some calcium-silicate insulated pipes was credited with having the same ZOI as the adjacent calcium-silicate insulated pipe (i.e., 5.45D if banded, 25D if unbanded). This was based on the cera-fiber being a relatively short span that was covered by the same lagging and fastening as was used on the adjacent calcium-silicate insulated piping.

to 0CAN090801 Page 5 of 55 3.b.2 Destruction ZOI and Basis Table 3.b.2-1 Destruction ZOIs and Basis Insulation Debris Source ZOI Basis Mirror foil 28.6D NEI 04-07 Transco reflective metal 2D NEI 04-07 insulation (RMI) foil Calcium-silicate1 (unbanded) 25D Wyle Labs Testing 2 Calcium-silicate 1 (banded) 5.45D NEI 04-07 Transco thermal wrap 7D Wyle Labs Testing 2 1 ZOI applies to any sections of cera-fiber insulation in these lines.

2 See section 3.b.1 3.b.3 Destruction Testing Destructive testing was conducted by Westinghouse at the Wyle Labs test facility for calcium-silicate insulation with screwed rather than banded lagging and Transco Thermal-Wrap blanket. The Westinghouse tests were documented in WCAP-16836-P Revision 0. The experimental program used a facility with a fluid supply pressure of 2000 psia and temperature of 530°F discharging from a 3.54 inch nozzle. The test pipe placement in front of the jet was calculated using the ANSI N58.2-1988 jet expansion model. Testing compensated for a slightly lower supply pressure by locating the test articles relative to the jet nozzle such that the stagnation pressure at the point of jet impingement in the test was calculated to be the same as with a supply pressure of 2250 psia. A total of four jet impingement tests were conducted. Three tests consisted of exposing Transco Thermal-Wrap to jet impingement forces and one test exposing stainless steel jacketed calcium-silicate insulation to jet impingement forces.

3.b.4 Debris Type Quantity See Table 3.b.4-1 for the four most limiting breaks.

Table 3.b.4-1 Quantity of Debris Generated for Break Locations Insulation Debris South North South South Type2 Units Break Break Break Break (within ZOI)

$1 S2 S4 S6 Mirror foil' ft2

<55000

<45000

<20000

<55000 Transco RMI foil1 f

<7000

<1000

<6000 Calcium-silicate f

<50

<40

<25

<50 Transco Thermalwrap f

0.0 0.0

<50 0.0 Cera-Fiber Insulation W

<0.75

<0.5

<1.5 1 Foils were measured by surface area.

2 Other breaks were bounded by those shown in the table.

3.b.5 Miscellaneous Materials The total surface area of signs, placards, tags, tape and similar foreign materials in the containment following efforts to remove these potential debris sources was less than 100 ft2.

The containment strainer blockage was less than this total based on the 75% area coverage guidance in NEI 04-07 for this type material, providing significant margin to the 200 ft2 allowed for foreign material blockage in the strainer qualification tests.

to OCAN090801 Page 6 of 55 3.c Debris Characteristics The objective of the debris characteristics determination process is to establish a conservative debris characteristics profile for use in determining the transportability of debris and its contribution to head loss.r

1. Provide the assumed size distribution for each type of debris.

2. Provide bulk densities (i.e., including voids between the fibers/particles) and material densities (i.e., the density of the microscopic fiberslparticles themselves) for fibrous and particulate debris.

3. Provide assumed specific surface areas for fibrous and particulate debris.

4. Provide the technical basis for any debris characterization assumptions that deviate from NRC-approved guidance.

3.c.1 Size Distribution ANO-2 conservatively credited 100% transport of fiber, coating, and latent particulate debris to the strainers. Only calcium-silicate insulation has been credited with less than 100% transport, which was supported by erosion and fines transport testing as discussed in section 3.e. RMI material was found to have a non-conservative effect on strainer head loss testing and was.

therefore excluded from the final strainer qualification tests to avoid possible beneficial effects.

The size distribution of the debris used for strainer head loss testing was conservatively. based to maximize strainer head'loss potential. Calcium-silicate insulation was pulverized into fines/powder. Fiber insulation was shredded into fines and very small pieces. Paint chips were sieved to achieve 2-4 mm size pieces. The RMI foils used in early strainer head loss tests were shredded and crumpled. This treatment of debris characteristics was conservative relative to the guidance provided in NEI 04-07.

3.c.2 Bulk Densities The bulk and material densities for fibrous and particulate debris were consistent with those reported in NEI 04-07. For the ANO-2 specific materials, the following bulk and material densities were used:

Bulk Density Material Density, Calcium-silicate (lbm/ft3) 14.5 144 Thermal-Wrap (lbm/ft3) 2.4 159 Cera-Fiber (lbm/ft3) 8.0 156 to 158 Qualified Coating - Epoxy (lbm/ft3) 94 n/a Qualified Coating - Primer (lbm/ft3) 205 n/a Unqualified Coating (lbm/ft3) 94 n/a The bulk density of inorganic zinc primer of 205 Ibm/ft3 was obtained from Carboline for their CZ-1 1 zinc primer, This value was a more accurate representation of the dry film density of zinc primer versus the value provided in NEI 04-07, which was for pure zinc powder without any fillers or binders used in the primer compound.

3.c.3 Surface Areas Surface area assumptions were not applicable to the strainer qualification testing performed for ANO-2. The particulate size used for the coatings surrogate was 600-mesh which was in the nine-micron size range to approximately match'the ten-micron size for coatings particulate discussed in NEI 04-07. The coatings surrogates are further discussed in section 3.h.

to 0CAN090801 Page 7 of 55 3.c.4 Debris Characterization Deviations The ANO-2 containment sump strainer qualification was performed with a bounding case that conservatively assumed 100% transport of fiber, coating, and particulate debris. Therefore, these debris types were not evaluated for characteristics with regard to transportability. Only calcium-silicate insulation was credited with less than 100% transport, which was supported by erosion and.fines transport testing discussed in section 3.e. Debris characteristics for strainer testing have been considered and comply with the guidance provided in NEI 04-07.

3.d Latent Debris The objective of the latent debris evaluation process is to provide a. reasonable approximation of the amount and types of latent debris existing within the containment and its potential impact on sump screen head loss.

1. Provide the methodology used to estimate quantity and composition of latent debris.

2. Provide the basis for assumptions used in the evaluation.

3. Provide results of the latent debris evaluation, including amount of latent debris types and physical data for latent debris as requested for other debris.

4. Provide amount of sacrificial strainer surface area allotted to miscellaneous latent debris.

3.d.1 Quantity Estimate Walkdowns were performed at ANO-2 to collect samples throughout containment on a wide variety of surfaces and at various elevations to document potential debris quantity and composition in accordance with NEI 02-01.

3.d.2 Basis for Assumptions Per NEI 04-07, 15% of the latent debris was comprised of fiber, and the remaining 85% was comprised of particulate. It was assumed that the debris was normally distributed for a given sample type. This assumption is supported by plant walkdown observations that debris distribution appeared to be uniform for a given surface type.

3.d.3 Evaluation Results Based on data collected in the walkdowns, the amount of latent debris was less than 100 pounds. Margin exists in the strainer qualification testing and downstream effects analysis for fiber and particulate loading above currently calculated debris generation quantities as noted in Table 3.f.5-1. This margin can be used to address larger latent debris totals in the future, if necessary.

3.d.4 Sacrificial Strainer Surface Area Strainer qualification testing assumed 200 ft2 of surface area was blocked by miscellaneous latent debris.

3.e Debris Transport The objective of the debris transport evaluation process is to estimate the fraction of debris that would be transported from debris sources within containment to the sump suction strainers.

1. Describe the methodology used to analyze debris transport during the blowdown, washdown, pool-fill-up, and recirculation phases of an accident.

2. Provide the technical basis for assumptions and methods used in the analysis that deviate from the approved guidance.

to OCAN090801 Page 8 of 55

3. Identify any computational fluid dynamics (CFD) codes used to compute debris transport fractions during recirculation and summarize the methodology, modeling assumptions, and results.

4. Provide a summary of, and supporting basis for, any credit taken for debris interceptors.

5. State whether fine debris was assumed to settle and provide basis for any settling credited.

6. Provide the calculated debris transport fractions and the total quantities of each type of debris transported to the strainers.

3.e.1 Debris Transport Methodology' ANO-2 conservatively has considered 100% transport of fiber, coating, and latent particulate debris to the strainers. Only calcium-silicate insulation has been credited with less than 100%

transport, which was supported by erosion and fines transport testing conducted for ANO. RMI material was found to have a non-conservative effect on strainer head loss testing and was therefore excluded from the credited strainer tests to avoid possible beneficial effects.

Downstream effects analysis credited 75% transport of Transco RMI and 1.6% of Mirror RMI to the strainer. Thus, only calcium-silicate insulation was applicable to debris transport analysis for strainer head loss testing.

The current analysis conservatively assumes 100% transport of miscellaneous latent debris (i.e., tape, stickers, etc.) of the type materials identified as credible sources. It is anticipated that additional sources of miscellaneous latent debris, could possibly continue to be identified beyond those currently considered. Future disposition of miscellaneous latent debris is expected to include credit for settling, transportability, or lift velocities on a case-by-case basis.

CFD modeling of the containment basement flow was performed to evaluate debris transport conditions. Additional testing was conducted regarding the erosion and debris transport characteristics of calcium-silicate insulation consistent with that-installed at ANO-2.

Since the transport analysis was based on calcium-silicate testing performed for ANO, the debris transport methodology in Appendices III and VI of the SE associated with NEI 04-07 was not used. No credit has been taken for reduction in the available calcium-silicate volume due to ejection of the material into regions not exposed to spray washdown, nor for any material washed into inactive flow regions of the basement during pool fill-up.

CFD modeling of the containment basement and break flows was used to establish bounding values of minimum flow velocities that the calcium-silicate fines and debris would be exposed to in the flow paths to the containment sump strainer. The basic methodology used for the transport analysis was:

" A three-dimensional CFD model was developed to analyze the flow patterns in the containment sump during post-LOCA recirculation.

Break S6 was chosen for CFD analysis since it was expected to result in the most flow out of the'D-rings' interior due to the direction of the break flow.

The CFD scenarios model the minimum post-LOCA containment water level, which was conservative for debris transport since it leads to higher velocities within the pool. The velocity through the sump strainer was not impacted since the strainer was fully submerged at the minimum water level.

to 0CAN090801 Page 9 of 55 The CFD scenarios model the maximum post-ILOCA flow rate of approximately 7,000 gpm through the sump to maximize water velocity in the pool.

No credit was taken in the transport analysis for debris interceptors.

" The limitations/observations pertaining to the CFD analysis were:

a) Major inlet flows significantly affect the flow patterns inside the D-rings and in part of the area outside the D-rings, particularly the area adjacent to the D-rings access opening.

b) There is a single large opening to the D-rings. If a part of this opening is blocked, the flow patterns in the region adjacent to concrete columns D, E, F, and G would be significantly different.

c) The simulations presented in the CFD analysis were for a specific water height. For small change in water depth (e.g., a few inches), at the same distribution of flow rates, the flow patterns were expected to be similar, although the magnitudes of the upper velocities would be different. For larger changes in water height, the flow patterns would be different.

d) The temperature of the water was not a major contributor to the flow patterns.

e) The flow pattern could change significantly if one side of the sump pit strainer was congested.

The CFD analysis was used in conjunction with erosion and transport tests conducted by Fauske and Associates to quantify the amount of calcium-silicate insulation that could be expected to reach the containment sump strainer as discussed in section 3.e.5 below.

3.e.2 Deviations The guidance in NEI 04-07 for calcium-silicate insulation was that 100% of the affected material was disintegrated into small fines and 100% of the small fines were transported to the sump.

Exceptions to these assumptions have been taken and are described in section 3.e.5.

3.e.3 CFD Codes A three dimensional CFD model was developed to analyze the flow patterns in the containment sump during post-LOCA recirculation. This model was created using Fluent CFD software (Version 3d, segregated, standard k-epsilon, Release 6.1.22). The limiting scenario, Break S6, investigated using the CFD model is shown in Table 3.e.3-1.

Table 3.e.3-1: Limiting Scenario Investigated using CFD Break Description Flow Out of Break S6 Cold leg suction break (30" Break flow enters sump pool with a round profile; flow ID) in south SG cavity has a horizontal and vertical velocity component.

See section 3.e.5 for details of calcium-silicate erosion and transport testing, including CFD modeling results used in the analysis.

3.e.4 Debris Interceptors No credit was taken in the transport analysis for debris interceptors.

to 0CAN090801 Page 10 of 55 3.e.5 Settling Guidance in NEI 04-07 assumes that 100% of small fines transport to the sump strainer. During initial strainer tests conducted for ANO it was observed that calcium-silicate fines would settle in the test flume. Stirring for significant time periods was necessary to maintain the calcium-silicate fines in suspension long enough for them to enter the strainer cartridges.

Testing was conducted by Fauske and Associates to determine the transportability of calcium-silicate fines. Bounding velocities of the basement flow, taken from the CFD models, of 0.15 feet per second (fps) and 0.25 fps were used in the testing. These velocities exceed those predicted between the SG cavities and the containment sump strainer. Tests were conducted for 24-hour and 72-hour exposure times for one-inch thick layers of pulverized calcium-silicate fines. Following the exposure time periods, the sample tray was dried and weighed. The before and after weights were then compared to determine the amount of material removed from the tray, including material that settled on the floor downstream of the tray that would not have been transported to the strainers.

The largest percentage mass lost with the 0.25 fps velocity was 5.8% over 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , and with the 0.15 fps velocity was 2.6% over 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The transported mass values were approximately constant between the 24-hour and 72-hour tests. If the three-day result was used as a "rate" of transport, the 30-day transported fraction based on the maximum mass reduction test would be 45%.

Testing was conducted at room temperature. To address potential dissolution of calcium-silicate insulation at elevated temperatures as documented in NUREG-6772, additional tests were conducted. These tests did not show a temperature dependency on dissolution of calcium-silicate pieces.

The transport test sample thickness of one inch may not be prototypic of the calcium-silicate fines layer on the containment floor, and test results would yield a larger relative percentage of transported fines if a thinner layer were used for testing. However, the results were believed to be conservative relative to the layer thickness due to the velocities present in the containment basement (per CFD analysis) being much lower than even the 0.15 fps lower test value. Thus, if perfectly distributed across the basement floor the calcium-silicate layer would be significantly thinner than one inch, but the layer would be subjected to much lower velocities than those tested. If the calcium-silicate fines were concentrated near the higher velocity regions, then the layer would be closer to or exceed one inch thickness, but the velocities outside of the affected SG cavity were bounded by the lower tested value. The net effect of these two variables indicates that application of the 0.25 fps transport results should provide a conservative application. The test data also shows no time dependency. One-day erosion data was very similar to the three-day data. The lack of an increasing rate with time indicates that significant conservatism would also result from applying a 30-day rate fraction to the results.

to 0CAN090801 Page 11 of 55 Testing was also conducted at Fauske and Associates to determine if erosion of large calcium-silicate pieces would be expected to occur. Tests were conducted at a flow velocity of 0.7 fps with one-inch and two-inch cubes of calcium-silicate insulation. Exposure times of 17, 45, 66, 90, 112, and 135 hours0.00156 days 0.0375 hours 2.232143e-4 weeks 5.13675e-5 months were included. The largest percentage mass reduction was 13.9% for a one inch cube and 8.3% for a two-inch cube. The eroded mass for each sample size was approximately constant (within +/- one standard deviation of the mean value) and was not dependent on exposure interval. If this lack of time dependency was conservatively ignored and a 30-day erosion fraction was determined using the largest percentage mass lost, then 41%

and 59% mass were lost from the two-inch and one-inch cubes, respectively. Testing was conducted at room temperature based on tests performed similar to those documented in NUREG-6772. These tests showed that a temperature dependency of calcium-silicate erosion/dissolution was not indicated. The tests consistently showed a higher mass-lss percentage for the one-inch cubes compared to the two-inch cubes. This was believed to be based on the surface area to mass ratio.

Most of the "erosion" was thought to be related to disturbed material on the sides of the cubes from the cutting/preparation phase with wash-off of these disturbed edges contributing to most of the observed weight change. Data from the one-inch cubes was used as a conservative value, since they showed a larger percentage weight reduction. Data documented in NUREG-6808 provides information regarding size distribution of calcium-silicate insulation debris generated by simulated breaks at varying distances. This data shows that at the distances tested, the mass fraction of released debris pieces less than one inch was small

(<25% of mass of pieces released). Thus, the use of the higher erosion values associated with the one-inch test cubes was conservatively bounding.

Testing only addressed erosion of fully immersed pieces representative of pieces on the basement floor versus pieces that may be trapped on platform grating in the SG cavity and exposed to containment spray droplet impingement. The test velocity of 0.7 fps was conservative since this value greatly exceeds CFD predicted velocities of the flow streams between the affected SG cavity and the sump strainer. This velocity was also twice the bulk tumbling velocity of 0.35 fps for calcium-silicate pieces noted in NUREG-6772. Thus, material potentially exposed to higher velocities inside the affected SG cavity would be transported outside of the cavity and settle out in the lower velocity regions between the cavity and the sump strainers.

Application of calcium-silicate erosion data requires establishing an expected ratio of large pieces versus fines and small pieces. A specific ratio was not listed in NEI 04-07 due to the assumption that 100% of the large pieces erode into fines. However, test data documented in NUREG-6808, Table 3-6 provides information on the size distribution of calcium-silicate debris for simulated breaks ranging from 5D to 20D to the target. This data shows that the amount of dust or fines combined with pieces less than one inch ranged from 15% to 30%. Thus, assuming 60% of calcium-silicate debris was large pieces and 40% was fines is considered a conservative distribution.

There are two major periods following a loss-of-coolant accident (LOCA) that must be considered for complete analysis. The first period is when the sump temperatures are at elevated and net positive suction head (NPSH) margin is at a minimum. The first period is conservatively bounded by 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . The second period continues for 30 days when debris loading may be at a peak, but considerable NPSH margin is available. Application of the erosion and transport data yields the following information provided in Table 3.e.5-1 (three-day erosion uses 4.7-day erosion data of 13.9%):

to OCAN090801 Page 12 of 55 Table 3.e.5-1 Erosion and Transport Data Initial Large Piece Finita Lrgiee Total Transported Net Fines at Strainer Fines Erosion 3-day 40%

13.9% of 60%

49%

5.8% of 49%

2.9%

30-day 40%

59% of 60%

76%

45% of 76%

35%

While these numbers were arrived at using relatively conservative treatment of the test data, it is recognized that considerable uncertainty exists when extrapolating laboratory test conditions to a post-LOCA environment. Significant additional margin has been applied to these numbers by applying an adjustment equivalent to neglecting the effects of transport reduction. This did not consider the transport analysis to be invalid, but it is a composite correction to further conservatively address uncertainties with both the transport and erosion test data. This results in a very substantial increase (multiple of 16.9x) in the amount of calcium-silicate fines assumed present in the initial 72-hour period and more than doubles the final calcium-silicate to be addressed for the final head loss value.

Table 3.e.5-2 Credited Calcium-silicate Fines at Strainer

% Calcium-silicate T Fines at Strainer 3-day 49%

30-day 76%

3.e.6 Debris Transport Fractions and Total Quantities:

Table 3.e.6-1 Debris Fraction at Sump and Debris Quantity at Sump Debris Type Fraction of Debris Units Debris at Generated S

Qny Sump Break S6 Sump SS Mirror RMI Foil ft2 N/Al

<55000 N/A1 SS Transco RMI Foil ft2 N/Al

<6000 N/A1 Calcium-silicate (3-day/30-day) f 0.49 / 0.76

<50 23.6 / 36.6 Cera-Fiber ft:7 1.00

<2

<25 / <38 Qualified Coatings f

1.00

<4.75

<2 Unqualified Coatings f

1.00

<0.75

<4.75 Foreign Materials ft2 1.003

<100

<0.75 Latent Debris Ibm 1.00

<85,

<100 1 RMI debris source was not included in strainer testing due to non-conservative impacts on debris bed.

2 Reference Table 3.f.5-1 for comparison of generated debris versus quantity in strainer head loss testing.

3 Foreign material debris may be evaluated for transport reduction in the future as noted in 3.e.1.

to OCAN090801 Page 13 of 55 3.f Head Loss and Vortexing The objectives of the head loss and vortexing evaluations are to calculate head loss across the sump strainer and to evaluate the susceptibility of the strainer to vortex formation.

1. Provide a schematic diagram of the ECCS and CSS.

2. Provide the minimum submergence of the strainer under small-break LOCA (SBLOCA) and large-break LOCA (LBLOCA) conditions.

3. Provide a summary of the methodology, assumptions, and results of the vortexing evaluation. Provide bases for key assumptions.

4. Provide a summary of the methodology, assumptions, and results of prototypical head loss testing for the strainer, including chemical effects. Provide bases for key assumptions.

5. Address the ability of the design to accommodate the maximum volume of debris that is predicted to arrive at the screen.

6. Address the ability of the screen to resist the formation of a "thin-bed" or to accommodate partial thin-bed formation.

7. Provide the basis for the strainer design maximum head loss.

8. Describe significant margins and conservatisms used in the head loss and vortexing calculations.

9. Provide a summary of the methodology, assumptions, bases for the assumptions, and results for the clean strainer head loss calculation.

10. Provide a summary of the methodology, assumptions, bases for the assumptions, and results for the debris head loss analysis.

11. State whether the sump is partially submerged or vented (i.e., lacks a complete water seal over its entire surface) for any accident scenarios and describe what failure criteria in addition to loss of NPSH margin were applied to address potential inability to pass the required flow through the strainer.

12. State whether near-field settling was credited for the head-loss testing and, if so, provide a description of the scaling analysis used to justify near-field credit.

13. State whether temperature/viscosity was used to scale the results of the head loss tests to actual plant conditions. If scaling was used, provide the basis for concluding that boreholes or other differential-pressure induced effects did not affect the morphology of the test debris bed.

14.State whether containment accident pressure was credited in evaluating whether flashing would occur across the strainer surface, and if so, summarize the methodology used to determine the available containment pressure.

to 0CAN090801 Page 14 of 55 3.f.1 Schematic Diagrams See Figures 3.f.1-1 and 3.f.1-2.

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ET to OCAN090801 Page 16 of 55 3.f.2 Minimum Submergence The minimum reactor building flood level, >7 feet, and used to determine the submergence of the strainer assembly. The strainer cartridge submergence is approximately one foot for the perforated plate flow path. The high point of the plenum roof is approximately equal to the minimum flood level. The minimum containment flood level does not credit release of RCS inventory, but does include inventory from the Safety Injection Tanks (SITs). The water holdup calculation for the refueling canal deep ends does credit RCS water volume of approximately 6600 gallons based on only LBLOCA breaks creating sufficient debris to allow obstruction of the lower flow path through the drains. The minimum level is conservative relative to any LBLOCA scenarios. While it may be possible for a SBLOCA to occur that does not result in release of the SITs but still results in sump recirculation, such a condition would result in significantly lower debris generation and would not be bounding. The strainer head loss for any SBLOCA would be minimal. Even if the water from the SITs were not credited and the water holdup calculated in the refueling canal deep ends associated with maximum LBLOCA debris were removed from the minimum level inventory, the strainer cartridge surface areas would remain fully submerged.

3.f.3 Vortexing Evaluation In addition to the re-designed sump strainer and plenum, the sump also contains grating cages installed around each train's intake piping. The cages were part of the original sump design and were not affected by the recent GSI-1 91 related modifications. A series of tests were performed by Western Canada Hydraulic Laboratories to qualify the original sump strainer design. This included tests to determine if vortexing would occur within the sump. A number of full scale tests were performed without the strainer in place showing that the grating cage alone prevented the formation of vortices. The tests involved varying submergence height, flow rate, and intake piping hydraulics. The range of tested conditions is noted in section 3.f.8.

Testing of the grating cage showed that vortices were not present at water depths as low as 54 inches (4.5 feet) above the sump pit floor at elevation 331.5 ft., or a water elevation of 336 ft.

Since the sump is vented, the minimum water level within the containment sump is not static. It was determined by the containment water level minus the head loss across the screen. To determine the maximum strainer head loss margin that still protects the tested minimum water level to prevent vortexing, the minimum water level to prevent vortexing (elevation 336 ft) was subtracted from the minimum containment flood level which is above elevation 343.5 ft.), for a margin of at least 7.5 feet. Thus, provided strainer head loss remains less than 7.5 feet the water level inside the strainer plenum assembly will remain above the minimum tested water level to prevent vortexing.

3.f.4 Head Loss Testing Final containment sump strainer head loss qualification testing was performed at a test flume facility constructed by Fauske and Associates. Initial strainer testing was performed by CCI; however lack of test facility availability resulted in the need to have an additional test facility constructed to support timely completion of testing. Testing was performed with spare ANO strainer cartridges.

The test facility scaling factors were determined from the ratio of surface area of strainer in the test facility to surface area of strainer installed in the plant (minus area allowance for foreign material debris blockage of 200 ft2). The tested strainer cartridges were identical to those installed at ANO-2, other than the total height of the assembly (i.e., test facility module was ten strainer pockets tall compared to 13 pockets in the ANO-2 strainers), therefore the only scaling of the strainer was associated with the area of the two cartridges in the test facility compared to the area of those installed in the plant. Since credit was not taken for near-field settling, the flow through the test facility was also scaled based on the strainer area ratio, to establish a velocity to OCAN090801 Page 17 of 55 through the strainer openings consistent with what would be present at the installed strainer.

The debris and chemical loading used this same scaling ratio.

Debris materials consisted of calcium-silicate insulation, thermal wrap fiberglass, ceramic fiber insulation, and silicon-carbide as a surrogate for coatings and latent particulate. Paint chips of Carboline 890 epoxy were also used. The paint chips were prepared using a sieve to obtain a size small enough to maximize transportability but large enough to potentially block the 1/16" strainer openings. Debris preparation included pulverizing the calcium-silicate into fines and shredding the fiberglass insulation into fines and very small pieces. The fiber fines were soaked in water to have them in suspension prior to addition to the flume in order to avoid having material floating on the surface of the flume. The fibers were also separated into multiple containers to avoid a concentrated mix of fibers that could re-agglomerate into larger clumps prior"to being added to the test loop. The fiber addition buckets were not mixed with any other material to maximize the transport and distribution of the fibers. The silicon-carbide was ordered as 600-mesh (nine-micron average) and did not require processing. The RMI foils used in early tests were shredded and crumpled prior to addition. Paint chips were sieved to achieve 2mm to 4 mm (1/12" to 1/6") size pieces.

Debris addition was performed in sequences with the fiber material added first and stirred as needed until essentially all material was transported into the strainer. The calcium-silicate insulation was added next, followed by the silicon-carbide and paint chips. Near-field settlement of test debris in the strainer facility was avoided by stirring to achieve as close to complete transport into the strainer cartridges as possible. Stirring was performed manually with care taken not to disrupt or disturb the debris bed established inside the strainer pockets, but only as needed to re-suspend settled materials from the test flume floor in front of the strainer. The stirring was repeated periodically as needed to re-suspend settled materials. After some period of time the test facility water would become clearer due to particulate filtration, providing visual evidence that the vast majority of the test debris had entered the strainer cartridges.

Confirmation that the remaining settled debris (i.e., trace particles and paint chips) was not consequential to strainer head loss was provided by the absence of increasing head loss peaks following repeated stirring. After head loss stability was achieved, additional calcium-silicate and fiber was added to measure more than one debris load condition.

The qualification test addressed three distinct test conditions with the first being the initial 30 minutes of sump recirculation when a possible low-pressure safety injection (LPSI) pump failure to trip at the start of recirculation was considered as the bounding single failure. The second condition was a debris only condition for elevated temperature conditions when pump NPSH was the limiting parameter for strainer head loss., The debris load for this condition was conservatively taken as the initial three-day period relative to debris erosion and transport totals for the calcium-silicate insulation, with all of the other debris assumed to be present. While the LPSI flow test condition had already conservatively included all of the debris loading to address the initial three-day period, an additional amount of fiber and calcium-silicate debris was added to the strainer to establish conservative margin for the test results. The test loop flow was also reduced from the two-train plus one LPSI pump flow to two-train flow for the head loss measurement comparison for NPSH limits. The calcium-silicate insulation debris loading was subsequently increased to the 30-day debris loading total (with additional margin) followed by the sequential addition of chemical precipitate debris.

Testing was not conducted for a 30-day period; however, head loss was monitored to ensure maximum values were reached. The debris beds included thin to ultra-thin fiber beds which were sometimes much less than 1/8". Filtering clean-up of the test flume water provided additional confirmation of thin-bed type filtration in addition to the elevated head loss to 0CAN090801 Page 18 of 55 measurements. The head loss characteristics of the debris beds produced an initial peak in head loss once all debris was transported into the strainer, but the head loss subsequently decreased over time to a relatively stable value.

Since the head loss characteristics of the debris bed did not show an increasing trend over time, and the early peak values were used for qualification, there was no need to run extended duration tests. The fiber bed with 100% debris loading was considerably less than 1/8" and therefore did not support compaction due to settling or potential breakdown of fibers. The initial settling of the particulate and fiber bed resulted in a reduction in the peak head loss with a stable value typically reached within the first few hours of operation. The credited qualification test included approximately 26 hours3.009259e-4 days 0.00722 hours 4.298942e-5 weeks 9.893e-6 months of operation with debris only conditions, followed by four days of additional testing involving additions of chemicals precipitate materials and head loss monitoring.

The results of the strainer qualification tests show that the strainer head loss remains below the available NPSH margin and the structural design limits. The results of strainer head loss testing with and without chemical effects are provided below. Detailed discussion of the chemical effects testing and analysis are included in section 3.o.

Maximum Head Loss for 2-train + 1 LPSI pump (single failure) flow:

<0.7 ft (at equivalent test flow that bounds maximum flow per analysis)

Maximum Allowable Head Loss with LPSI pump fail-to-trip:

>0.975 ft (at maximum flow per analysis)

Maximum Head Loss w/o Chemical Debris measured with 2-train flow:

<1.0 ft (at test flow equivalent to maximum 2-train flow per analysis)

Maximum Allowable Head Loss w/o Chemical Debris with 2-train flow:

>1.75 ft (at 7,035 gpm maximum design flow)

Maximum Head Loss with Chemical Effects Debris:

<3.5 ft (at test flow equivalent to maximum 2-train flow per analysis)

Maximum Allowable Head Loss with Chemical Effects Debris:

>6 ft (maximum head loss per structural limit)

Table 3.2.6-1 Qualification Test vs. Allowable Head Loss (HL)

Measured Allowable HIL HL' LPSI + 2-Train

<0.7 ft

>0.975 ft Flow w/o Chem 2-Train Flow

<1.0 ft

>1.75 ft w/o Chem 2-Train Flow w/

<3.5 ft

>6 ft Chem Effect debris load The strainer testing maximum head loss values were conservatively taken from peak readings versus the lower stable values. The peak readings were normally associated with debris addition or stirring with the maximum head loss not sustained but settling to lower final readings.

to 0CAN090801 Page 19 of 55 Testing of different debris mixtures established that for ANO-2, the thinner fiber bed with higher calcium-silicate debris associated with break S6 (A-Cold Leg) provided a bounding case for head loss, both with debris only and with chemical effects compared to the higher fiber but lower calcium-silicate S4 break (pressurizer surge line).

3.f.5 Debris Loadinq The strainer cartridges can hold the entire debris load predicted by the debris generation calculation with the exception of RMI foils. The dominant insulation type was RMI with essentially all of the RCS, SG, and pressurizer insulation being RMI. The RMI foil volume would not fit into the strainers and was found to have either non-conservative or negligible effect on strainer head loss. The material does not readily lay flat against the strainer perforated plate. It forms a three dimensional layer or pile that can act as a pre-filter that catches fibers and other debris types, keeping them off of the strainer surface. The foil can also bury insulation that was on the floor of the test facility. If the non-RMI debris was added first and time was allowed for it to enter the strainer (which was non-prototypic), then the problem of burying other insulation types under RMI can be avoided. Even in this configuration the RMI fragments would be expected to puncture and disturb the established fiber and particulate debris bed and cause a reduction rather than an increase in head loss. Final qualification tests were conducted without RMI foils as a conservative measure to maximize head loss.

The strainer head loss qualification test included bounding volumes of fiber, calcium-silicate, coatings and particulate debris to allow margin for future changes to the debris generation totals as outlined below:

Table 3.f.5 Comparison of Debris Generation to Strainer Test Debris Loads South North South South Test Test Test Debris Type Units Break Break Break Break (S6)

(S6) 30-day Debisype isB

,w/LPSI 2-train (S6) w/

SI S2 S4 S6 Chem.

Latent Fiber lbs

<15

<15 Total Fiber lbs

<15

<130

<25 31 39.6 39.6 Calcium-silicate W

<50

<40

<25

<50 23.71 35.62 55.143 Coatings ft3

<7

<6.5

<2

<5.5 7.5 7.5 7.5 (Qual. & Unqual.)

<65 2

Latent Particulate lbs

<85

<85 127.5 127.5 127.5 1 Calcium-silicate equivalent to 47.4% of 50 3

, which was almost the entire erosion and transport fraction for the first three days being applied in the first 30 minutes with less than one sump water inventory turnover.

2 Calcium-silicate debris loading was 71% of the 50 ft3 bounding debris generation total. Based on 49% transport and erosion total in first three days, tested quantity was equivalent to 72.6 ft3 total calcium-silicate generated or >145% of the bounding calcium-silicate volume.

3 Calcium-silicate debris loading was 110% of the 50 ft3 bounding debris generation total.

Based on 76% transport and erosion total for 30 days, test quantity was equivalent to 72.6 ft3 total calcium-silicate or >145% of the bounding calcium-silicate volume.

3.f.6 Thin-Bed Effect As previously noted, testing has shown that "thin-bed" formation can and does occur with the ANO-2 strainer. Due to the limited fiber source term, insufficient material exists to create thicker (i.e., > 1/8") fiber beds. Thus, none of the issues related to thick fiber beds were applicable to ANO-2. Issues such as settling or compaction within the fiber layer and debris addition sequencing for maximum thick bed head loss do not apply due to the low available fiber content.

to 0CAN090801 Page 20 of 55 The strainer qualification tests established thin-bed conditions, but with acceptable head loss results. Without the formation of a thin-bed, the screen would be left with open area and minimal resulting head loss. The head loss with the thin-bed alone, without particulate material, was also minimal. The particulate filtering capability of the strainer thin-bed was confirmed both by increased head loss and filtration of the test water to essentially clear conditions after sustained operation, with visual observation and stirring of the test flume floor confirming that the particulate had not simply settled out. Earlier tests had shown that thin-bed conditions could be established with considerably smaller fiber thicknesses than the nominal 1/8" layer initially discussed in industry documents as the thin-bed "threshold". A series of sensitivity and qualification tests were necessary to determine which debris load condition with regard to fiber layer thickness and available quantity of calcium-silicate insulation produced the most limiting results.

3.f.7 Maximum Head Loss The strainer design maximum head loss was controlled by NPSH margin and the structural qualification limit. Vortex protection limits were another potentially limiting parameter due to the vented strainer assembly design and must be compared to the NPSH and structural limits to ensure the most restrictive parameter was applied. NPSH margin was the most limiting head loss parameter when containment sump temperatures are at or above 200°F as discussed later in section 3.g. The most limiting NPSH margin for temperatures above 200°F was >1.75 feet for two-train flow and >0.975 feet with a single LPSI pump failure to trip combined with two-train flow. When the containment sump temperatures are below 200°F, the NPSH margin exceeds the design structural limit of >6 feet for the strainer and plenum assembly. The vortex protection head loss limit of >7.5 feet, discussed above in section 3.f.3, was less restrictive than the NPSH limit or structural design limit.

3.f.8 Margins Some of the more significant margins and conservatisms used in the strainer head loss testing and analysis are as follows:

Debris generation analysis used conservatively established ZOIs to maximize the amount of insulation potentially affected. ANO strainer testing has shown that calcium-silicate was a principal source of elevated head loss when combined with the limited amount of fiber available. The use of a 25D ZOI for calcium-silicate insulation with lagging fastened by screws rather than banding was conservative in that it was based on a test that did not release any material from the jet impingement test. The 5.45D ZOI applied to banded calcium-silicate was also considered conservative given that banding spacing tighter than that used in the qualifying Ontario Power Group (OPG) test was installed, and the ANO lagging is stainless steel versus the weaker aluminum lagging that failed in the OPG qualification tests.

Debris transport has been treated conservatively with all fiber, coatings, and latent debris 100% transporting to the strainers with sizes intended to maximize head loss.

Testing was conducted by ANO to establish erosion and transport values for calcium-silicate insulation. As discussed in section 3.e.5, the test results supported much larger reductions in the calcium-silicate arriving at the strainer than the values credited by ANO-2, which provides for significant conservatism in the application of the results.

A large surface area strainer, approximately 4837 ft2, has been installed that is relatively tall (5+ ft) with three dimensional screening surfaces that are oriented in various directions, all of which would make if very difficult for the screen not to have open surface area. Even if all of the fines and particulate did transport to the strainer, it would to 0CAN090801 Page 21 of 55 not readily distribute over the entire surface area and certainly would not distribute evenly. Strainer pockets closer to the floor would be expected to accumulate a larger proportion of materials due to low transport velocities available to lift debris into the upper strainer pockets.

Even with 100% destruction of fiber materials to fines, and 100% transport, and perfectly even distribution, all of which were very conservative assumptions individually, the reduced amount of fiber material available in ANO-2 only supports formation of a thin-bed fiber layer. While testing has shown that this fiber layer was sufficient to filter particulate and chemical precipitates, it was significant that the available source was very small, thus any cause of reduced fiber on the screens could yield open screen area with minimal head loss.

Debris addition during strainer testing aided in establishing non-prototypic but conservative conditions for debris distribution in the screens by adding materials into a flowing test flume and pouring materials at locations to assist getting materials into upper pockets of the strainers. Stirring was used to avoid settling of material. Materials were maintained segregated to minimize clumping or agglomeration.

" Debris material that resulted in a beneficial effect, such as RMI, was excluded from the testing. Due to ANO-2 being almost an entirely RMI plant, the vast majority of the debris created was RMI-related. The RMI debris on the containment floor, particularly in the affected SG cavity, could provide a beneficial function similar to debris interceptors by trapping, burying, or capturing fines and particulate material and thereby limit the ability of more detrimental insulation types from reaching the strainer. RMI was excluded from the strainer tests after it was observed that it was not creating a conservative (i.e., higher head loss) effect.

" No viscosity correction was applied to the elevated temperature head loss used for comparison with NPSH head loss limits, although the NPSH limit was only applicable to sump temperatures of 200°F or higher. The debris bed head loss response to flow changes indicates that a viscosity correction could be applied (i.e., no adverse jetting or blow through effects), although it was excluded as a conservative approach.

" The chemical effects head loss at one-train equivalent flow was less than half the available NPSH margin without applying viscosity corrections. (This measured head loss was not being credited against the pump NPSH conditions, but was only noted as a comparative point.)

The peak chemical effects head loss with two-train maximum flow would be below the available NPSH margin if corrected for lower viscosity at elevated temperatures. The responsiveness of the debris bed head loss to flow changes was supportive of such a correction in spite of the elevated head loss present with chemical effects debris. (This head loss was not being credited against the pump NPSH conditions, but was only noted as a comparative point.)

The difference in temperatures between when NPSH was no longer the limiting parameter for strainer head loss, 200°F, and when chemical precipitate effects on autoclave strainer filtration times began to appear, 1300F, in the bounding ANO-1 test with aluminum concentrations many times that available in ANO-2, was substantial (i.e.,

70°F).

to OCAN090801 Page 22 of 55 Strainer head loss qualification tests used debris quantities that significantly exceeded the amounts determined by the debris generation calculation as noted in Table 3.f.5-1 and Section 3.o.2.7.ii for chemical precipitates. These excess amounts were added to establish margin within the tested debris quantities that could be credited to allow for future modifications, material discoveries, degradations or other issues. Therefore, the excess of tested material was not a conservatism in regards to not being available as useable margin, but it does show that the ANO-2 test results readily bound actual conditions in the plant with margins sufficient to allow future adjustments to the supporting analysis without impacting the strainer testing maximum head loss values.

The following conservatisms in Table 3.f.8-1 were used during the vortex testing.

Table 3.f.8-1 Conservatism used in Vortex Analysis Design Tested Minimum water depth from sump floor

>145 54 to 143.4 (inches)

Maximum flow (gpm)1 3532.5 4325 to 8636 Water temperature (OF) 210 57 to 184 Maximum circulation(ft /sec) 3.2 9.1 Maximum size of circulation cell (ft.)

16 18 Intake pipe Reynolds Number 1.5 x 106 0.59 to 3.19 x 106 3532.5 gpm was the maximum single-train flow used in NPSH analysis.

Since the presence of the sump strainer acts to slow intake velocities, the conclusions from the original testing of the grating cage were bounding *and remain valid for the protection against vortex formation.

3.f.9 Clean Strainer Head Loss The clean head loss of the strainer cartridges themselves was negligible, because the velocities in the screen holes and the cartridge channels were comparatively very low. This was.

confirmed during strainer testing. The internal head loss of the overall strainer and plenum assembly was dominated by the exit losses from the strainer modules into the plenum. Since this loss was not reflected in the strainer head loss tests, it was included as a reduction in the available NPSH in the pump NPSH calculation.

The approximate clean head losses in the strainer and plenum assembly for various flows are shown in Table 3.f.9-1.

Table 3.f.9-1 Head Loss Head Loss Flow 0.25 ft.

6165 gpm (1 HPSI pump, 2 spray pumps) 0.33 ft.

7065 gpm,(2 HPSI pumps, 2 spray pumps) 1.07 ft.

12765 gpm (1 LPSI pump, 2 HPSI, and 2 spray pumps) to OCAN090801 Page 23 of 55 3.f.10 Debris Head Loss Debris head loss qualification was based upon field test data. Initial analytical modeling was conducted to assist in sizing the proposed replacement strainers. The final design consisted of installing the maximum possible surface area that could be installed given field constraints and then reducing debris loading until acceptable head loss was achieved. The early modeling of strainer head loss was not intended to be maintained as an active document relative to strainer head loss; therefore, additional information is not presented here.

3.f.1 1 SubmergenceNenting The sump design consists of a fully submerged structure for all events requiring recirculation with a vent that extends above the maximum containment flood level. The impact of a vented strainer has been considered for vortex protection criteria and the potential presence of a water level inside the strainer assembly that is lower than the water level outside due to the debris head loss. These conditions do not impact the effective strainer surface area since the strainer remains fully submerged. No additional failure criteria were applied.

3.f.12 Near-Field Settling The debris addition process during strainer qualification testing did not credit near-field settling.

The debris materials were manually stirred to achieve as close to complete transport into the strainer cartridges as possible (i.e., only trace particles or isolated paint chips visible in flume and continued stirring was not causing a head loss increase), thereby avoiding near-field settling.

3.f.13 Scaling Scaling of viscosity to correct for temperature differences between test and accident conditions was conservatively not credited; ambient temperature head loss readings were used. Strainer tests with large head losses typically exhibit blow-holes or jetting streams of water through the strainer, which can affect the head loss response to velocity changes. Velocity changes were made during the credited qualification test to evaluate the responsiveness of the debris bed to head loss. Poor head loss responsiveness to velocity change indicates that a similar lack of responsiveness to reduced viscosity may also exist and therefore the test results would not be suitable for viscosity correction. Most of the lower head loss tests did not exhibit this perforated debris bed jetting, and their head loss was responsive to flow changes. The debris only test results were considered acceptable for application of viscosity corrections based on both visual observation during the test (i.e., lack of blowholes) and the responsiveness of the debris bed head loss to flow changes. Since chemical effects were credited to occur at lower temperatures, a viscosity correction was not applicable. The chemical effects debris bed head loss was responsive to flow changes in spite of the presence of jetting through the bed; therefore, viscosity corrections appear to be acceptable, although as noted none were applied.

3.f.14 Accident Pressure Credit The sump strainer design includes a vent which equalizes the internal air pressure of the strainer structure with that of containment. Thus, flashing of recirculating fluid would not be present since a change in pressure would not be experienced. The head loss across the strainer would result in only physical level difference between the water inside and outside of the sump strainer structure.

3.g Net Positive Suction Head The objective of the NPSH section is to calculate the NPSH margin for the ECCS and CSS pumps that would exist during a LOCA considering a spectrum of break sizes.

1. Provide applicable pump flow rates, the total recirculation sump flow rate, sump temperature(s), and minimum containment water level.

to OCAN090801 Page 24 of 55