ML082100452
| ML082100452 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 07/25/2008 |
| From: | Holm D A Constellation Energy Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GL-04-002 | |
| Download: ML082100452 (8) | |
Text
I , a Dave Holm Plant General Manager R.E. Ginna Nuclear Power Plant, LLC 1503 Lake Road Ontario, New York 14519-9364 585.771.5205 Dave.A.Holm
@constellation.com Constellation Inery Nuclear Generation Group U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Document Control Desk July 25, 2008
SUBJECT:
R.E. Ginna Nuclear Power Plant Docket No. 50-244
REFERENCES:
Second Supplemental Response to NRC Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" (a) Letter from John Carlin (Ginna LLC) to Document Control Desk (NRC) dated February 29, 2008, Supplementary Response to Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" (b) NRC Generic Letter 2004:02: "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" (c) Letter from Patrick D. Milano (NRC) to Mary G. Korsnick (Ginna LLC), dated October 4, 2006, R. E. Ginna Nuclear Power Plant -Approval of Extension Request for Completion of Corrective Actions in Response to Generic Letter 2004-02.By letter dated February 29, 2008, R.E. Ginna Nuclear Power Plant (REGNPP) provided a supplemental response (Reference (a)) to Generic Letter (GL) 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors,"(Reference (b)).As approved by the NRC in Reference (c), certain information requested by GL 2004-02 was not included in Ginna' s February 29, 2008 submittal pending completion of chemical effects testing and the actual installation of the sump modification during Ginna's Spring 2008 refueling outage. The requisite testing and installation has been completed.
The Attachment to this letter provides supplemental information to the responses provided in Reference (a).If there are any questions or if additional information is require, please contact Mr. Dave Wilson at (585) 771-5219 or at David.F.Wilson
@Constellation.com Very truly your, Dave A. Holm A//Jo,/60/ qjg?
STATE OF NEW YORK TO WIT: COUNTY OF WAYNE I, Dave Holm, being duly sworn, state that I am Plant General Manager, R.E. Ginna Nuclear Power Plant, LLC (Ginna LLC), and that I am duly authorized to execute and file this request on behalf of Ginna LLC. To the best of my knowledge and belief, the statements contained in this document are true and correct. To the extent that these statements are not based on my personal knowledge, they are based upon information provided by other Ginna LLC employees and/or consultants.
Such information has been reviewed in accordance with company practice and I believe it to be reliable.Sub cribed and sworn before me, a Notary Public in and for the State of New York and County of V a ,qn e this -day of ..J2 , .-WITNESS my Hand and Notarial Seal: 1ýot lic MyCommission Expires: I RICHARD A. JOHNSON UOate I NOTAýRY PUBLIC, STATE OF NEWYORK I No. 01d06082344 Al QUALIFIED IN WAYNE COUNTY 200 A.m"Spra" ."T IZEF.jý (-L 2004-02 SECOND SUPPLEMENTAL RESPONSE cc: S. J. Collins, NRC D. V. Pickett Resident Inspector, NRC (Ginna)P. D. Eddy, NYSDPS J. P. Spath, NYSERDA bcc: G. Detter C. W. Fleming, Esquire J. Carlin D. A. Holm D. F. Wilson J. Pacher WPLNRC XXXXXX COMMITMENTS IDENTIFIED IN THIS CORRESPONDENCE:
None.
ATTACHMENT 1 REGNPP GL 2004-02 SECOND SUPPLEMENTAL RESPONSE ATTACHMENT 1 REGNPP GL 2004-02 SECOND SUPPLEMENTAL RESPONSE Sump Strainer Modification During the Ginna 2008 refueling outage, approximately 4000 ft 2 of strainer surface area were installed and connected to Sump "B" for Emergency Core Cooling System (ECCS) pump suction. All planned modifications to the sump structure were completed in support of the strainer modification.
To allow for the final strainer installation, the 600 ft 2 of interim passive strainer surface area, installed as a mitigating measure during the 2006 refueling outage, were removed. Additionally, the flow diverter walls, installed to alter the direct flow path of debris to the sump, were removed, as was the 95 ft 2 of Johnson screen inside the sump. All sump modifications, as described in the February 2008 Supplementary Submittal
[i], were completed.
Chemical Effects Testing As cited in Reference i, Ginna chemical effects testing was first conducted in November 2007 at the Control Components, Incorporated (CCI) multi-functional test loop in Winterthur, Switzerland.
This testing yielded higher than expected head loss test results. Investigations into the cause of the high head loss concluded that the test methods used by the strainer vendor, CCI, were overly conservative.
CCI's method of developing the chemical precipitant surrogate was to add constituent chemicals directly into the test loop, in an aqueous environment that is representative of the containment recirculation pool. Significantly more precipitant was generated in this fashion, as this method allowed little control of the type and quantity of precipitants generated.
This resulted from additional constituent parts beyond that existing in the actual recirculation pool being added to the test loop.As a result, additional strainer testing was performed in February of 2008. The testing .conducted utilized the methods and processes described in WCAP-16530-NP for the formation of the sodium aluminum silicate precipitant surrogate
[ii]. Westinghouse was engaged to assist CCI in the development of a chemical precipitant formation procedure
[iii]. Prior to chemical effects testing, bench top testing was conducted to confirm the settling rate of the precipitant formed using the WCAP-16530-NP methods [iv]. Settling rates were confirmed to be > 9.5 ml per 10.0 ml sample after I hour, well within the range specified in the WCAP.Chemical effects testing conducted in February 2008 utilized the worst case debris loading determined through the Ginna Debris Generation and Transport Analyses [v, vi]. The chemical effects testing debris loading used the greatest quantity of each debris type from all break cases to ensure a bounding conservative result. No additional conservatism was applied to the fiber and particulate quantities, as had been done in previous tests. Additionally, the quantity of qualified coatings used in the testing was representative of a 1OD Zone of Influence (ZOI), and the quantity of degraded or unqualified coatings was quadrupled from that provided in the analysis, resulting in the equivalent of 6302 ft 2 of degraded/unqualified coatings [vii]. The chemical precipitant quantity used in the testing was a scaled quantity, based on the amount calculated via the WCAP- 16530-NP methodology.
The total quantity of sodium aluminum silicate used in the testing was scaled from the 71.3 kg calculated
[viii].The fiber and particulate debris was added to the test loop in a manner consistent with the NRC draft guidance [ix], on thin bed formation.
Small amounts of fiber and then particulate were added in quantities needed to form a thin bed. No evidence of thin bed formation was detected based on head loss measurements.
The remaining fiber and particulate debris was added to the loop to complete the full debris load testing. The chemical precipitant surrogate of sodium aluminum silicate was prepared outside the test loop in a mixing tank and transferred to the test loop by way of a transfer pump, as described in WCAP-16530-NP.
All pH readings and precipitant settling rates met the criteria set in the WCAP [x]. Multiple tests with the same debris loading were run in order to confirm the test results, There was very little variation in the test results among the tests conducted, thereby establishing repeatability.
After letting the test loop run for approximately 4 days for each test, following the addition of the debris, the maximum recorded head loss across the test strainer was determined to be 95.2 mbar (normalized to 200 C) [xi].
This maximum head loss value is equivalent to 29.7 mbar corrected to the minimum design temperature of 195' F.This is equivalent to 0.99 ft WC. This value was used in the overall strainer head loss report [xi].Head Loss The total worst case sump strainer head loss is the total of the worst case full debris head loss, including chemical precipitants, as tested during the chemical effects testing, and the head loss through the strainer ducts and channels at maximum flow rate. The head loss through the strainer for the worst case debris load, asdetermined through testing and discussed above, was determined to be 0.99 ft WC. The total head loss through the ducts and channels at a flow rate of 2300 gpm was determined to be 0.131 ft WC [xi]. Therefore, the total head loss under worst case conditions is 1.12 ft WC. No sacrificial strainer area was identified or credited for latent debris in Ginna's February 29th submittal
[i]. Therefore, the head loss value of 1.12 ft WC does not credit the 118 ft 2 of sacrificial area (explained below) designated for tape, labels, and tags. Otherwise, the head loss would be approximately 3%lower.The minimum Residual Heat Removal (RHR) pump Net Positive Suction Head (NPSH) margin for the Large Break Loss of Coolant Accident (LBLOCA), excluding the impact of the sump strainers, is 2.99 ft WC. Therefore, including the worst case head loss due to full debris laden sump strainer, the remaining NPSH margin for the LBLOCA is 1.87 ft WC (2.99 ft WC -1.12 ft WC).The RHR pump flows and debris loading for the LBLOCA case bound that for the Small Break Loss of Coolant Accident (SBLOCA).
The minimum RHR pump NPSH margin for the SBLOCA, excluding the impact of the sump strainers, is 2.64 ft WC. Therefore, including the bounding worst case head loss for the LBLOCA case, the remaining NPSH margin for the SBLOCA case is 1.52 ft WC (2.64 ft WC -1.12 ft WC).Strainer Surface Area The effective surface area of the strainer installed at Ginna was nominally taken as 4000 ft 2.The actual total effective surface area, as calculated in the CCI Head loss Report [xi] is 4089 ft 2.The strainer surface area used during strainer testing for the purpose of scaling the debris quantities was taken as 3971 ft 2.Therefore, there is 118 ft 2 of strainer surface area that can be attributed as sacrificial area to accommodate other debris sources, not accounted for in the debris generation analysis, such as masking tape, labels, and tags.Debris Source Term During the 2008 refueling outage, a concerted effort was undertaken to remove tape, labels, and tags from containment.
However, some of these debris sources remain. A walkdown of containment identified and quantified these additional debris sources [xii]. These debris sources were applied to the 118 ft 2 of sacrificial strainer area that is in excess of that credited for strainer testing [xi]. The debris sources and quantities identified are shown in Figure 1 below.Figure 1: Additional Debris Sources Identified Debris Source Quantity Transport and Impact Total Against Sacrificial Area on Strainer Surface Area Tape and Stickers 17 ft 2 100% 17 ft 2 Signs and Placards 92 ft 2 100% 92 ft 2 Containment Liner Insulation Jacket Sealant 5 ft 2 100% 5 ft 2 Total 114 ft 2 There is sufficient strainer sacrificial area to accommodate these additional debris sources.
Coatings During the 2008 Ginna NPP refueling outage the overall condition of containment coatings was assessed and documented.
Ginna has implemented a new containment coatings assessment procedure to go along with the current reptask that generates a work order to perform coating assessments every refueling outage. EP-3-P-0601
[xiii] has been developed using EPRI guidelines and Ginna's current licensing basis. This procedure outlines roles and responsibilities in performing, reporting on, and approving containment coatings condition assessments.
The following describes the conclusion from the walkdowns performed during the outage and other inspections that reported degraded coatings.The general condition of coatings in containment is good. Degraded and suspected unqualified areas were found that could have an impact on the head loss across the Sump "B" strainers during a design basis accident.
The total amount of degraded coatings was not significant.
An estimate of the total amount, which includes an inspection of the containment dome and license renewal inspection reports, is approximately 300 ft 2.About 30 ft 2 of that amount was repaired, and work orders have been initiated to repair the remainder during the 2009 refueling outage.A thorough walkdown of containment was performed to identify valves, electrical panels, and other components that could possess unqualified coatings and conservatively estimate the surface areas. The results of this walkdown, which was performed after the initial degraded coatings walkdown, showed that there are approximately 1230 ft 2 of potentially unqualified coatings.
However, approximately 120 ft 2 of potentially unqualified coatings were in the I OD ZOI for coatings destruction, and are already included in the conservative estimate of surface area in the debris generation calculation
[v].Therefore, the total quantity of coatings left in containment for monitoring and future repairs is approximately 1400 ft 2 (1110 (potentially unqualified)
+ 270 (degraded)).
This is well within the margin represented in Reference v, which was quadrupled, and used for the sump strainer qualification testing (1575.5 ft 2 x 4 = 6302 ft 2) [vii].Downstream Effects -LOCADM An evaluation was performed by Westinghouse, using the LOCADM code, to predict the growth of fuel cladding deposits and to determine the clad/oxide interface temperature that results from coolant impurities entering the core following a LOCA. The results of this evaluation are presented in Figure 2[xiv]. These results show that the calculated fuel cladding deposits and clad/oxide interface temperature do not challenge the acceptance criteria.The stated acceptance criterion is that the maximum cladding temperature maintained during periods when the core is covered will not exceed a core average clad temperature of 800'F. This acceptance basis is applied after the initial quench of the core and is consistent with the long-term core cooling requirements stated in 10 CFR 50.46 (b)(4) and 10 CFR 50.46 (b)(5).An additional acceptance criterion is to demonstrate that the total debris deposition on the fuel rods (oxide + crud +precipitate) is less than 50 mils. This acceptance criterion is based on the maximum acceptable deposition thickness before bridging of adjacent fuel rods by debris is predicted to occur [xv].For the minimum sump water volume cases, LOCADM was also run with increased quantities of debris -in accordance with the "bump-up factor" methodology described in Reference xvi. The "bump-up factor" had a negligible effect on both the total thickness and fuel cladding temperature.
Figure 2: LOCADM Results Case Scale Thickness Total Deposition Total Deposition Max Clad (Pim) Thickness Thickness Temperature
('F)(pim) (mils)Maximum sump volume 37.1 329.1 12.96 378.5 Minimum sump volume 49.8 341.8 13.46 378.5 Minimum 'Bump-up' 51.6 343.6 13.53 378.5 References
[i] "Supplementary Response to Generic Letter 2004-02, 'Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors'," dated February 29, 2008.[ii] Q.003.84809, CCI, AG Specification, "Double Sided Chemical Effect Head Loss Test Specification," Revision 1.[iii] TP- 120202- I, Westinghouse Technical Paper, "Procedure for Generation of Chemical Surrogates for R.E. Ginna Nuclear Power Plant," February 1, 2008.[iv] LTR-SEE-I-08-49, Westinghouse TripReport, "Chemical Effect Head Loss Test at CCI Winterthur for R.E. Ginna NPP, February 4-8 and February 19-21, 2008," dated March 5, 2008.[v] CAL-CONS-3237-02, Alion Design Calculation, "Ginna Reactor Building GSI-191 Debris Generation Calculation," Revision 1.[vi] CAL-GINNA-4376-03, Alion Design Calculation, "Ginna GSI-191 Debris Transport Calculation", Revision 0.[vii] DBCOR 2008-0002, "Chemical Effects Testing Debris Load -2008 Tests," dated January 28, 2008.[viii] CN-SEE-1-07-49, Westinghouse Report, "Sump pH versus Time Profile and Chemical Effects Evaluation for R.E. Ginna Nuclear Power Station", Revision 0.[ix] "Draft Guidance for Review of Final Licensee Responses to Generic Letter 2004-02, 'Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors", dated September 27, 2007.[x] T-2139-I and T-2139- I-Rep, CCI, AG Protocol, "Chemical Head Loss MFT Filter Performance Test."[xi] 3SA-096.077, CCI, AG Report, "Head Loss Calculation Including Chemical Effects," Revision I.[xii] 170-1387463, Ginna Technical Report, "Quantification of Additional Debris Sources Identified During 2008 Containment Walkdown," dated May 13, 2008.[xiii] EP-3-P-0601, "Containment Coating Condition Assessment Procedure," Revision 00000.[xiv] CN-SEE-I-08-48, Westinghouse Report, "LOCADM Analysis for R.E. Ginna," Revision 0.[xv] OG-07-477, "Responses to the NRC Request for Additional Information (RAI) on WCAP-16793-NP, 'Evaluation of Long-Term Cooling Considering Particulate, Fibrous and Chemical Debris in the Recirculating Fluid' (PA-SEE-0312)," October 2007.[xvi] OG-07-534, "Transmittal of Additional Guidance for Modeling Post-LOCA Core Deposition with LOCADM Document WCAP- 16793-NP (PA-SEE-0312)," December 2007.-4-