ML20140E299

Proposed Criteria for ECCS Strainer Design,Technical Evaluation Rept

ML20140E299
Person / Time
Site:	Hatch
Issue date:	06/02/1997
From:	Rao D SCIENCE & ENGINEERING ASSOCIATES, INC.
To:	NRC
Shared Package
ML20140E302	List: ML20140E299 ML20141A189 ML20141A198
References
SEA-97-3703-A:1, NUDOCS 9706110318
Download: ML20140E299 (12)

Text

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, SEA 97-3703 A:1 l

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PROPOSED CRITERIA FOR ECCS STRAINER DESIGN EDWIN I. HATCH NUCLEAR PLANT- UNIT 1 TECHNICAL EVALUATION REPORT l

1 June 2,1997 Prepared by Dasari V. Rao Science and Engineering Associates,Inc.

6100 Uptown Boulevard NE, Suite 700 Albuquerque,NM 87110 I

. Prepared for U.S. Nuclear Regulatory Commission Washington, DC 20055 l

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D0b Attachment

TECilNICA1. EvAtIJATION OF l_ " PROPOSED CRITERIA FOR ECCS STRAINER DESIGN" EDwlN 1. HATCII Nt' CLEAR PLANT- UNIT 1,

1.0 INTRODUCTION

In' response to Bulletin.96-03, the Southern Nuclear Operating Company (SNC) has submitted

! ' Proposed Criteria for ECCS Strainer Design, Edwin 1. Hatch Nuclear Operating Plant - Unit l' for US Nuclear Regulatory Commission (NRC) review [Ref.1). Science and Engineering Associates, l Inc. (SEA) is tasked to review the submittal by NRC.

, Re resolution option is based on installation of passive large capacity suction strainers, designed l and manufactured by the General Electric Company (GE). The submittal estimated debris loading l

on the strainer following a postulated ' worst-case' break using methodology provided by the i Boiling Water Reactors Owners Group (BWROG) in the Utility Resolution Guidance (URG) '

document [Ref. 2].. Estimates for quantities of fibrous debris, sludge, and paint-chips transported to l

the strainer were evaluated on a plant-specific basis, but using guidance provided in the URG. On the other hand, generic estimates provided in the URG were used for Dust and Dirt; and Rust from '

unpainted structures. In addition, Transportable Foreign Material with a surface area of 1.0 ft2 was used to account for miscellaneous debris that may exist in the suppression pool. ,

De plant intends to design strainers subject to single failure analysis, which resulted in availability of one (1) Residual Heat Removal (RHR) and two (2) Core Spray (CS) pumps for injection into the core. The large capacity strainers to be installed on the RHR and CS pumps will be sufficiently large to accommodate the debris and result in head loss less than the available NPSH Margin of 9.3 ft-water for RHR and 12.2 fl-water for CS. The corresponding flow rates are 7700 GPM and 4725 GPM for RHR and CS, respectively. The flow rates are consistent with ECCS design criteria and accident analysis sections of the Utility Final Safety Analysis Reports (UFSAR) [Ref. 3]. Estimates of Available NPSH incorporated a credit of 5 psig for containment pressure. The utility has stated that design of strainers without reliance on containment pressure is not practical.

The utility did not provide actual sizes of the strainers to be installed on the RHR and CS pumps.  !

Instead, it provided a m'ethodology proposed by GE for sizing the strainers [Ref. 4]. It is the intent i of the utility to finalize the strainer design upon receiving NRC approval of the ' Proposed Criteria j for ECCS Strainer Design' and, if necessary, to forward the design configuration to NRC staff I when the design is completed. SEA is reviewing Ref. 4 as part of this task.

SEA performed a preliminary review of the licensee submittal and forwarded a Request for i Additional Information (RAI) to the utility. On May 13,1997 in a conference call with the utility,  !

SEA provided detailed explanation of the RAI. Utility response to the RAI is contained in their letter (dated: May 28, 1097), ' Response to Request for Additional Information on Proposed Criteria for ECCS Strainer Design' [Ref. 5]. The utility response provided required clarifications regarding debris generation estimates and reduced their estimate of the quantity of sludge to be used in sizing the strainers from initial value of 920 lb. listed in Ref. I to 675 lb.

The focus of the SEA review of the submittal [Ref.1] and the supporting documentation [Ref. 4 and 5],is the following:

! 1. To assess adequacy / accuracy of the utility estimated debris loading to be used in sizing the ,

strainer. In particular, SEA focused on determining if the breaks were selected in accordance with Regulatory Guide 1.82, and if the methodology used by the utility has been previously science &

Wsoc#Nshc. 1 2 SEA-3704-010-A:1, Rev. I

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TECHNICAL EVALUATION OF !

" PROPOSED CRITERIA FOR ECCS STR.4INER DESIGN#

EDWIN 1. HATCH NUCLEAR PLANT - UNIT I,  ;

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approved by NRC to provide reasonable estimate for debris generation and transport. Finally, ,

has the plant made efforts to ensure that head loss predicted for the ' worst-case' break is, in t fact, higher than that corresponding to all other possible breaks.

2. To assess accuracy of the strainer sizing criterion provided by the vendor. In particular, SEA focused on a review of the experimental data provided in the GE topical report [Ref. 4] and its usage by GE to derive the head loss correlation.

SEA did not devote any efforts to examine validity of ficensee's assumption related to containment pressure. He Licensee determined that NPSH calculation was performed under 10 CFR 50.59.

l l To achieve these goals SEA performed a series of calculations. Calculations related to debris j generation are summarized in Appendix-A, whereas calculations related to the GE stacked disc '

! strainer assessment are documented in Appendix-B. The following sections summarize SEAS l

- findings.

l-2.0 CONTRACTOR FLNDINGS 2 I

l 2.1 Selection of the Break: i The utility explicitly stated that break location was selected not based on criterion of High Energy

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l Line Breaks (HELB), which refers to locating the break close to the high stress points. Instead, l break was selected so as to maximize the quantity of debris generated. [Ref. 5, Response to  ;

Question #2]. Our calculations suggest that selected break is located in the most congested part of  ;

the containment and it will most likely bound the fibrous debris generation estimates. Because the '

L remaining debris are particulate debris and are break-independent (except for Calcium Silicate), l break selected by the licensee will provide largest debris loading for sizing the strainers. Also, l stacked disc strainer is not expected to have the ' thin-bed effect' and hence Regulatory Position L 2.3.1.5 of Regulatory Guide 1.82, Rev. 2 does not apply. Note that Regulatory Position 2.3.1.5 requires the licensee to identify 'the medium and large breaks with largest potential particulate to insulation ratio by weight.'

SEA concludes that selection of the break is appropriate, and is consistent with the guidance provided in RG 1.82,1(ev. 2.

2.2 Debris Generation:

The utility used Method 3 of the URG to estimate the zone ofinfluence (ZOI) and the quantity of debris generated by the jets. The ZOI used by the licensee for estimating fibrous debris generation j l

is a sphere whose radius is approximately 12 x Diameter of the Recirculation Line (12D). This ZOI is about 4 times larger than the ZOI used in NUREG/CR-6224 [Ref. 6] in volume. De licensee estimated vaine of 580 ft3 of NUKON is slightly more than approximate value of 500 ft3 derived independently by SEA (see Appendix-A). Licensee used a smaller ZOI with a radius of SD to '

estimate damage to calcium silicate. SEA previously expressed reservation about accepting zone of influence for calcium silicate because both the ZOI and the size distribution were obtained using ,

insufficient data base. However, SEA does not believe this poses a serious challenge to strainer  ;

design because a) calcium silicate is located in the neck region of the drywell and is not likely to be a target for most of the breaks, and b) the total quantity of calcium silicate expected to be ,

transported is significantly smaller than the volumes of other particulate debris already assumed to

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l TECIINICAL EVAtt!AllON OF l " PROPOSED CRI1ERIA FOR ECCS STRAINER DESIGN" EDwlN I. HATCil Nt' CLEAR PLANT- UNIT 1, i

reach the strainer. Licensee screened out Urethane insulation as it has specific gravity substantially less than 1.

SEA concludes that usage of Method 3 of URG is acceptable and that licensee has appropriately estimated the quantity of debris generated. The estimated quantities of fibrous debris appear to provide a reasonable upper bound. Argument to screen out Urethane appears reasonable. The estimates of Calcium Silicate reaching the strainer (0 3ft ) will likely have little impact on the overall head loss (see Appendix-B), since significantly larger quantities of other particulate debris are included in the strainer design.

1 2.3 Debds Transport:

Licensee has determined that 100% of the generated debris for the ' worst-case' break was  !

contained above the lowest grating. SEA independently confirmed their finding. URG transport I factor of 0.28 was used by the licensee to estimate the total quantity of debris reaching the strainer. i

'Diis value was recommended by URG and includes 100% transport of small debris which amount to 22% of the total and 6.25% transport of the remaining large debris due to erosion. A transport factor of 1.0 was used for all other debris. A transport factor of 1.0 was used for suppression pool transport.

SEA believes that these transport fractions are reasonable and that estimated quantities appear to provide a reasonable upper bound for the quantity of debris loading on the strainer.

2.4 Debris Loadine on the Strainer:

The following table summarizes the debris loading assumed and its basis for each type of debris.

Type of Debris Quantity Comment Fibrous Debris (Nukon) 162 ft3 Checked independently by SEA.' Reasonable.

Calcium-Silicate 0 There may be some trace quantities of Ca-Si.

Sludge 675 lb. Estimate revised from 920 lb. in the original.

Dust and Dirt 150 lb. URG Number. Also NUREG/CR-6224 Rust from Unpainted 50 lb. URG Number.

Paint Licensee estimates. Not checked by SEA.

Inorganic Zinc 47lb.

IOZ with Epoxy topcoat 85 lb. No documentation provided for review.

Epoxy 71lb.

Unqualified Paint Coating 117 lb. Licensee estimates. Not checked by SEA.

Other (Trans. For. Mat.) 1.0 ft2 L:censee estimate. Actual survey information.

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TECIINICAL EVALUATION OF

" PROPOSED CRITERIA FOR ECCS STRAINER DESIGN" EDWIN 1. HATCII NUCLEAR PLANT UNIT I, These numbers and their rationale for usage appears reasonable. Note: The estimate for sludge l was revised from 920 lb. used in the original submittal, Proposed Criteria for ECCS Strainer i

Design,' (dated March 25,1997) to 675 lb. per Fax Memo, ' Response to Request for Additional Information (dated: May 28,1997).' According to the later memo 675 lb. was estimated based l on actual plant measurements for Hatch Unit 2. BWROG survey provides an estimate of 150 l

lblyr., which translates to 675 lb. for 3 cycle cleanings (each cycle of 18 months) planned by the utility.

The licensee should not use Transportable Foreign Material of 1.0 ft2 as a substitute for FME Program.

2.5 STRAINER DESIGN ECCS Operating Parameters The utility provided the following parameters for ECCS pumps:

System Flow Rate NPSH Available NPSH Required T pooi Comments

1. pumps (GPM) (ft-water) 0 (ft-water) F RHR 9600 45 20.7 165 Short-term (no throttle)

(4) 7700 26 16.7 209 Long-term (throttle)

CS 5900 45 18.5 165 Short-term (no throttle)

(2) 4725 26 13.8 209 Long-term (throttle)

The utility proposes to take credit for decreased ECCS flow after core reflood (=10 minutes post-LOCA) and thus reduced the flow from 9600 GPM to 7700 GPM. During long-term operation the suppression pool temperature is assumed to be 209 0F, which is higher than 202 0F used in the FSAR. As a result ofincreased suppression pool temperature, NPSH available decreased to 26 ft water, while at the same time NPSH required also reduced slightly (= 4 ft-water) due to reduction in ECCS flow.

l The NPSHavailable was estimated by crediting containment over-pressure of 5 psig. As noted j above SEA has not perfonned any calculations to examine accuracy of that assumption or its l consistency with licensing basis. Note that licensee determined to carry out NPSH calculation l under 10 CFR 50.59.

j The values used for flow rate and suppression pool temperature appear reasonable and are i consistent with UFSAR numbers. The licensee assumed scenario (i.e., higher flow at start-up, decrease after 10 m; lower suppression pool temperature initially and increase during long-term 1 operation) are consistent with accident analyses result in UFSAR.

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The single failure analysis by the plant assumes availability of two RHR pumps and one CS pumps in the present plant configuration. On the other hand, future modifications may change the single failure criterion to one RHR pump and two core spray pumps. Usage of the later case to design the strainer poses more severe constraints than the former, because the later one allows for accumulation of more debris on the RHR strainer and hence higher head loss (Note that l volume of debris collected on each strainer is proportional to the ratio of the flow through that I strainer to the total ECCS flow from suppression pool). Since the design criteria is not to loose 2 any of the pumps, the later case maximizes potential for loss of strainer if surface area is not Seiwe &

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TECIINICAL EVAll!ATION OF

" PROPOSED CRITERIA FOR ECCS STRAINER DESIGN"

, EDwiN I. IIATCII Nt' CLEAR PLANT - UNIT 1, sufficiently large. .

Head Loss Correlation and GE Strainer Si:ing Criteria:

The plant intends to use vendor provided head loss correlation and sizing methodology described in Ref. 4. The actual size of the strainers were not provided. The approximate strainer sizes were provided in Ref. S to be 40"-diameter and 49"-long GE stacked disc strainers for RHR and 34"-diameter and 35"-long GE stacked disc strainers for CS. However, the licensee stated that fabrication issues may influence in the selection of the strainer design.

SEA is independently reviewing Ref. 4 and has several concerns. These concerns relate to GE's usage of the strainer performance data and derivation of the head-loss correlation. SEA is not in a position to make ajudgment regarding the generic acceptability of the GE nethods at the present time as the work is in progress. In particular it is not clear if GE methodology will result in either realistic or conservative estimate of head loss for a generic plant. SEA recommends that such an evaluation instead be made on a plant-specific basis. To facilitate such a plant-specific evaluation it is recommended that the licensee finalize the strainer design and forward it to NRC for review.

3.0 DEFICIENCIES No serious deficiencies were noted regarding the criteria to be used for strainer design. Licensee is asked to finalize the design and forward their finalized strainer descriptions to NRC. This judgment does not reflect on licensee's usage of 5 psig for containment over-pressure. SEA believes this value to be larger than that most likely available during long-term operation.

However, licensee intends to perform NPSH calculations under 10 CFR 50.59 and independent of strainer design criteria.

4.0 CONCLUSION

S It is concluded that licensee estimated the quantity of debris reaching the strainers appropriately.

These methodologies are consistent with RG 1.82, Rev. 2 and other methods previously reviewed by the NRC. Licensee's choice of I ft2 of transportable material adds a reasonable conservatism, but should not be treated as an alternative to an effective Foreign Material Exclusion program. Licensee should provide finalized strainer design for NRC review (In the mean time SEA will be reviewing the approximate strainer information provided by the plant to facilitate quick-turn around).

5.0 REFERENCES

1. Southern Nuclear Operating Company, ' Proposed Critoria for ECCS Strainer Design, Edwin 1. Hatch Nuclear Plant - Unit 1,' Docket No. 50-321, March 25,1997.

2. BWROG. ' Utility Resolution Guidance for ECCS Suction Strainer Blockage,' NEDO-32686, November 20,1996.

3. Updated Final Safety Analysis Reports.

4. General Electric Company, ' Licensing Topical Report: Application Methodology for GE Stacked Disk ECCS Suction Strainer (Proprietary Information),' NEDC-32721P, March 1997.

5. Southern Nuclear Generating Company, ' Response to Request for Additional Information on Proposed Criteria for ECCS Strainer Design,' Docket No. 50-366, May 28,1997.

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l TECilNICAL EVALUATION OF

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( EDWIN I. HA rCil NUCLEAR PLANT - UNIT 1.

l Appendix-A '

Confirmatory Calculations Conducted by SEA to l Assess Accuracy of Utility Estimates of Debris Loading on the Strainer A.1 Selection of the Break The utility explicitly stated that break location was selected not based on criterion of High Energy Line Breaks (HELB), which refers to locating the break close to the high stress points.

Instead, break was selected so as to maximize the quantity of debris generated. [Ref.: See Response to Question #2 of Request for Additional Information].

Elevation of the break is 153' 1". It is about a foot above the upper grating. It is located in the raost congested part of the containment, with respect to location of other target pipes. It is very similar to RCA-J006 of the Reference plant of NUREG/CR-6224 [Ref.: NUREG/CR-6224, Page 3-3; UFSAR].

Likey :argets: a) Recirculation Line in which break occurred, b) Recirculation Manifold, c) l Recirculation Risers, d) Feed Water Lines, c) Main Steam Lines and f) ECCS Injection Line.

[Ref. NUREG/CR-6224, UFSAR].

During discussions with the utility they have sta:ed that several breaks were analyzed, and that

! selected ' worst-case break' bounds debris generation estimates.

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It is SEAS opinion that the utility selection of the break provides reasonable assurance that j estimated debris would be bounding in terms of the quantity of fibrous. Further calculations are i performed to ensure that the break bounds head loss estiraates. I I

l A.2 Debris Generation Estimates: 1 Utility used Method 3 ofthe URG to estimate zone ofinfluence. The following calculations

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were performed as san;ity check of utility estimates:

Insulation Ouantities in the Containment.-

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Type Volume Largest Pipe Location  ;

(ft3) OD' (in)

NUKON (un-jacketed) 2,300 26 + 6 All primary and ECCS piping, RCIC also.

Calcium Silicate 361 26 + 6 MSL above the top weld. Neck region.

Urethane 274 Unknown On chilled water supply pipes.

8 l Actual pipe size is unknown (SEA did not have this part of the FSAR). However, NUREG/CR 5640 l (Overview and Comparison of US Commercial Nuclear Power Plants) suggests a value between 24" and i

28" for the recirculation pipe OD. We selected a ,alue of 26". This selection is not expected to influence our calculations significantly.

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TECilNICAL EVALUATION OF

" PROPOSED CRITERIA l'OR ECCS STRAINER DESIGN" EDwlN I. HATCII Nt! CLEAR PLANT - UNIT 1 Urethane was screened out from the remaining calculations because it Hoats above water and, therefore, will not reach the strainer. Appears reasonable, althcogh no supporting documentation is provided to confirm this finding.

Zone ofInRuence (ZOh Estimates.-

Type Pdest' Pipe Size' Pdest A' Recirc. ' Final A (psi) Correction (psi) Correction NUKON (un-jacketed) 10 1.0 10 4708 1.0 4708 Calcium Silicate 160 0.5 80 1750 0.4 700 Ur: =

The URG experimental data for calcium silicate is from three tests for aluminum jacketed. Page

1. 157 provides damage information. Minimal damage is noted. These tests have limitations:

1. No tests were conducted between 19 L/D and 7 UD.

2. Data obtained at 7 UD may not be representative of the LOCA because of narrow nozzle used in the experiments.

3. Finally, Swedish experiments suggest that calcium silicate destruction is by erosion, which is proponional to the duration of exposure and temperature of thejet. BWROG tests did not address these issues.

Further explanation is provided in the SEA report fauivalent Sr>here Parameters:

Type of Volume of the ZOI Equivalent Radius Insulation (D')  % of Containment (D) (ft.)

NUKON (un-jacketed) 4708 =33% =l1D =26 Calcium-Silicate 700 =5% =5.5D =12 Comment:

1. These zones ofinDuence are reasonable. Note that for NUKON, NUREG/CR-6224 assigned a zone ofinnuence of about 7D compared to 12 D used by the utility.

2. In the case of calcihm silicate their zone ofinDuence is 5.5 D, which is slightly lower than the 7D used in the NUREG/CR-6224.

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8 j Table 2 of Utility Resolution Guidance (Page #46) l 2 Note #3 to Table 2 in Utility Resolution Guidance (Page #47)

• Table #1, Radial Off-set > 3D/2 of the Utility Resolution Guidance (Page #45)

' Note #5 to Table 1 in Utility Resolution Guidance (Page #46)

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l TECIINICAL EVALUATION OF

" PROPOSED CRITERIA FOR ECCS STRAINER DESIGN" EDWIN 1. HATCil NUCLEAR PLANT- UNIT 1, i

Sanitv check on the utility estimates ofinsulation tareeted:

Sys ID OD Type lhid Length Volume Targeted j Recirc. Line 26 Nukon 3 43.92 83.32 Recire. Manifold 16 Nukon 3 30 37.29 Recire. Risers 10 Nukon 2.5 60 40.89 Feed Water 16 Nukon 2.5 55.2 55.67 Main Steam Line 26

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Nukon 3 114.86 217.9 l ECCS Lines 16 Nukon 2.5 25 25.21 Valves etc. 40 Total = 500.27 l

Assumotions: j

1. NUREG/CR-6224 plant layout is similar to the Hatch plant layout. This assumption is expected to be reasonable.

2. Insulation Thickness as described by the Vendor during NUREG study.

SEA estimated volume ofinsulation targeted by the iet (or volume contained in a 12D sphere) is  :

500 ft3, which is slightly lower than the utility estimated value of 580 ft3 . This confirms that utility estimates are reasonable.

A.3 Location of the Debris Generated Utility stated that no debris is generated below the lowest grating. This appears reasonable for this postulated break location. The location of the break is 153', where as the location of the lowest grating is 127'. The elevation difference of 26' is approximately equal to 12D of the recirculation pipe. Thus, it :, reasonable to assume that no debris are generated below the lowest grating.

A.4 Debris Loadine on the Strainer  !

Fibrous debris reaching strainer: 580 ft3 x 0.28 (transport factor) = 162 A3 1

Type of Debris Quantity Comment Fibrous Debris (Nukon) 162 ft3 Checked independently by SEA. Reasonable.

Calcium-Silicate 0 There may be some trace quantities of Ca-Si. j Sludge 675 lb. Estimate revised from 920 lb. in the original.

Dust and Dirt 150 lb URG Number. Also NUREG/CR-6224 Rust from Unpainted 50 lb. URG Number. j Paint Licensee estimates. Not checked by SEA.

Inorganic Zinc 47lb.

IOZ with Epoxy topcoat 85 lb.

l Epoxy 71 lb.

Unqualified Paint Coating 117 lb. Licensee estimates. Not checked by SEA.

Other (Trans. For. Mat.). 1.0 ft2 Licensee estimate. Actual survey information.

The debris loading on the strainer appears reasonable.

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TECHNICAL EVALUATION OF

, " PROPOSED CRITERIA FOR ECCS STRAINER DESIGN" EDwlN I. HATOI NUCLEAR PLANT - UNIT 1.

Annendn-B Confirmatory Calculations Conducted by SEA to Assess Licensee Assumptions Related to Head less B.! Break Details The licensee has provided information for two breaks. The following table provides strainer loading for these twt breaks:

Debris Break #1 Break #2 Total RHR Strainer Total RHR Strainer Nukon 162 ft'(388 lb) 174lb. 84 ft'(200 lb) 90 lb.

Calcium. Silicate 0 0 40 lb. 17.9 lb.

Sludge 675 lb. 303lb. 675 lb. 303 lb.

Dust and Dirt 150 lb. 67.3 lb. 150 lb. 67.3 lb.

Rust from Unpainted 50 lb. 22.4 lb. 50 lb. 22.4 lb.

Paint -IOZ 47 lb. 21.1 lb. 47lb. 21.1 lb.

Paint - IOZ with Epoxy 85 lb. 38.2 lb. 85 lb. 38.2 lb.

Paint - Epoxy 71lb. 32lb. 71lb. 32lb.

Unqualified Paint 117 lb. 52.5 lb. I17 lb. 52.5 lb.

Other 1.0 ft2 1.0 ft2 1.0 ft2 1.0 ft:

EQl.G Total: Total quantity of debris introduced into the pool. Reproduced from Table in Section A.4.

RHR Strainer: Quantity approaching the RHR strainer calculated as: Total *(RHR Flow of 7700 GPM/ Net ECCS Flow of17150 GPM) ,

B.2 Interpretation of GE Data for Application to RHR Design GE Licensing Topical Report ' Application Methodology for GE Stacked Disk ECCS Suction Strainer (NEDC-32721P)' provides data for type of strainers proposed for use by the licensee.

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SEA has not endorsed the methodology proposed in this document. Instead, SEA is conducting the following back-of-the envelope calculations to get order-of-magnitude estimates of head loss.

! Assume that the strainer is 40" in diameter and 49" in hydraulic length as described in Licensee's response to the RA'. For such a strainer, SEA estimates a trough (or cavity) volume of 23 ft3 or it can accommod:ue approximately 55 lb. of the fibrous insulation within the

! cavities, without much increase in the head loss; typically about 2-3 foot-of-water or less (see Test #GE-3 and GE-7). However, the expected loading in the present case is much larger than 50 lb. implying that a thick bed ofinsulation will form on the strainer surface. Its effectiveness in filtering the particulate debris should be adequately modeled.

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TECIINICAL EVALUATION OF

" PROPOSED CRITERIA FOR ECCS STRAINER DESIGN" EDWIN I. HATCit NtJCLEAR PLANT . UNIT 1.

Two sets of data for fibrous and sludge mixtures at 7500 GPM; the results of the tests are given below:

Test Conditions AH GE-7 100 lb. Fiber + 500 lb. Sludge 130 in-H2O Less fiber loading than plant GE-3 50 lb. Fiber + 100 lb. Sludge 34 in-H 2O Less both fiber and part. load Clearly in both cases the strainer data cannot be used directly. One has to rely on the correlation developed by GE for design and strainer performance assessment.

B.3 SEA Assessment of GE Correlation SEA is in the process of reviewing data and head loss correlation reported by GE. In general, SEA identified following draw-backs related to GE Methodology:

1. The experimental data for sludge were obtained for lower strainer loadings than anticipated in the plant application. For example, raajority of the data were obtained for fibrous debris loading of 17 lb.,25 lb., and 50 lb., at which the cavities are not filled (i.e.,17 and 25 lb.) or only barely filled (50 lb.). Only few tests were reported for 75 lb. and 100 lb. where debris bed is expected to form on the strainer surface.

2. The correlation lacks theoretical basis for extrapolating head loss measurements obtained at lower strainer loading to the plant application (174 lb. of fibrous debris).

3. SEA is presently evaluating if the GE correlation nevertheless provides conservative head loss estimates. (Further discussions in a detailed report later).

B.4 Which Break should be used as the Design F, asis Break? Break #1 or Break #2.

Two types of calculations were performed to determine which form the worst case.

NUREG/CR-6224 Correlation:

For the conditions ofinterest NUREG correlation predicts that:

AP = K (1+0.549 )l.5 AL This gives that:

AP]/_AP2= (1+0.54q1)l3 AL}/(1+0.5492)l.5 AL2

+

t where AP is pressure in ft-water l

T) is sludge-to-fiber ratio filtered on the bed (not added to bed)  ;

Mc/M f si the particulate to fiber ratio added to pool  !

AL is the theoretical-thickness of the bed j The following table provides these variables for the plant application: i l

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l l TECIINICAL EVALUATION OF

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" PROPOSED CRITERIA FOR ECCS STRAINER DESIGN" EDwlN 1. HATCH NUCLEAR PLANT- UNIT 1. j Quantity Break #1 Break #2 I l

DLo 5.88 1.68 Mc/Mr 2.10 4.31 Filtration Efficiency 0.85 0.80 9 1.80 3.45 AP 1/_AP2 2.0 --

This clearly establishes that increase in particulate ratio does not compensate for increase in circumscribed thickness on the strainer. The Break #1 is the worst case.

GE Correlation: i AP = K (1+0.15 Mc/Mr) AL AP 1/,_AP2 = (1+0.15 91) AL 1/(1+0.1592) AL2 For this case it can be easily shown that Break #1 once again results as the worst-case break.

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