ML053180306
| ML053180306 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 06/09/2004 |
| From: | Richard Ennis Office of Nuclear Reactor Regulation |
| To: | Anderson C, Bores R, Scott Burnell, Clifford J, Dennig R, Dyer J, Florek D, Holden C, Howe A, Jasinski R, Kim T, Leeds E, Lobel R, Madden T, Kamal Manoly, Marsh T, David Pelton, Diane Screnci, Neil Sheehan, Sheron B, Skay D, Virgilio R, Scott Wall Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2004-0369 | |
| Download: ML053180306 (14) | |
Text
LRick Ennis - Fwd: State of Vermont comments on EPU and AST Pane 11I1 Page LRick Ennis Fwd: State of Vermont comments on EPU and AST From: Rick Ennis To: Allen Howe; Brian Sheron; Cliff Anderson; Cornelius Holden; David Pelton; Diane Screnci; Donald Florek; Donna Skay; Eric Leeds; James Clifford; Jim Dyer; Kamal Manoly; Neil Sheehan; Richard Lobel; Robert Bores; Robert Dennig; Robert Jasinski; Rosetta Virgilio; Scott Burnell; Scott Wall; Tad Marsh; Tae Kim; Thomas Madden Date: 619/04 12:08PM
Subject:
Fwd: State of Vermont comments on EPU and AST Attached are 2 letters from the State of Vermont that Bill Sherman just emailed to me. They provide State comments on the Vermont Yankee AST amendment request and the EPU amendment request. Note, these are the second set of comments from the State on each amendment request. We previously responded to the first AST letter on 12/16/03 and the response to the first EPU letter (NPSH issue) is with Jim Dyer for review (scheduled to be issued today).
The letter concerning the AST amendment request is one Bill previously told me he was sending in response to my routine request on whether the State had comments on the amendment. Based on the comments, we will not be able to issue the amendment by 6/30/04 as per the current schedule. I will pass this info on to the licensee. My plan is to coordinate with Tech Staff such that we can address the comments in the SE in parallel with sending a response back to the State. The issues concern SLC and the single failure criteria, quality standards for the ALT pathway, and reducing margin by increasing the allowed MSIV leakage.
The second letter was a suprise to me. It requests the NRC to perform independent calculations as part of the power uprate review in the areas concerning steam dryers, NPSH, and flow-induced vibration.
I will take both of these letters to the 5th floor so they can be Yellow Ticketed.
Thanks, Rick 415-1420
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Fwd: State of Vermont comments on EPU and AST Creation Date: 6/9/04 12:08PM From: Rick Ennis Created By: RXE@nrc.gov Recipients Action Date & Time twf5_po.TWFN_DO Delivered 06/09/04 12:08PM TJM (Thomas Madden) Opened 06/09/04 01:13PM nrc.gov kpl-po.KPDO Delivered 06/09/04 12:09PM CJA (Cliff Anderson) Opened. 06/09/04 12:09PM DJF1 (Donald Florek) Opened 06/09/04 12:11PM DLP1 (David Pelton) Opened 06/09/04 01:06PM DPS (Diane Screnci) Opened 06/09/04 12:18PM NAS (Neil Sheehan) Opened 06/09/04 12:18PM RJB (Robert Bores) Opened 06/09/04 08:13PM nrc.gov owfl_po.OWFN_DO Delivered 06/09/04 12:08PM ROV (Rosetta Virgilio) Opened 06/09/04 12:34PM SRB3 (Scott Burnell) Opened 06/09/04 12:27PM nrc.gov owf2_po.OWFNDO Delivered 06/09/04 12:08PM DMS6 (Donna Skay) Opened 06/09/04 12:57PM KAM (Kamal Manoly) Opened 06/09/04 12:08PM RML (Richard Lobel) Opened 06/09/04 03:07PM nrc.gov owf4_po.OWFN_DO Delivered 06/09/04 12:08PM AGHI (Allen Howe) Opened 06/15/04 09:01AM BWS (Brian Sheron) Opened 06/09/04 12:27PM CFH (Cornelius Holden) Opened 06/09/04 03:49PM EJL (Eric Leeds) Opened 06/09/04 02:01PM JED2 (Jim Dyer) Opened 06/09/04 04:09PM JWC (James Clifford) Opened 06/09/04 12:39PM LBM (Tad Marsh) Opened 06/09/04 12:27PM RJJ1 (Robert Jasinski) Opened 06/09/04 12:09PM RLD (Robert Dennig) Opened 06/09/04 01:05PM RXE BC (Rick Ennis) Opened 06/09/04 12:15PM SPW (Scott Wall) Opened 06/09/04 12:45PM
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No Security: Standard To Be Delivered: Immediate Status Tracking: Delivered & Opened
I Rick Ennis - Comments on EPU and AST Pane 1 1 I Rick Ennis Comments on EPU and AST Paae 1I From: Sherman, William" <William.Sherman~state.vt.ui>
To: "Rick Ennis (E-mail)" <rxe~nrc.gov>
Date: 6/9/04 11:11AM
Subject:
Dear Rick,
Today we signed out the attached letters regarding proposed Vermont Yankee amendments - one providing comments on EPU, the other on AST.
-- Bill Sherman
<<EPU commentsl.wpd>> <<AST commentsl.wpd>>
CC: "Dave Pelton (E-mail)" <dIpl @nrc.gov>, "Cliff Anderson (E-mail)" <cja~nrc.gov>, mBeth S (E-mail)" <bek~nrc.gov>
June 8, 2004 RE: Vermont Yankee Nuclear Power Station License No. DPR-28 (Docket No. 50-271)
Technical Specification Proposed Change No. 263 Extended Power Uprate - State of Vermont Comments Richard Ennis, Project Manager U.S. Nuclear Regulatory Commission Washington, D.C., 20555
Dear Mr. Ennis,
The state of Vermont, through its NRC state liaison officer, makes the requests identified below of the Nuclear Regulatory Commission staff (NRC) with regard to its review of the proposed Vermont Yankee power uprate. Vermont asks that NRC perform independent calculations in three areas to confirm the adequacy of the proposed uprate: 1) the adequacy the steam dryer with power uprate flow rates, 2) credit for containment overpressure for net positive suction head (NPSH) adequacy, and 3) flow-induced vibration adequacy of the main steam and feedwater systems. This request is consistent with NRC's Review Standard for Extended Power Uprates (RS-001).
Background
On March 15, 2004, the Vermont Public Service Board requested the NRC perform an independent engineeringassessment' of Vermont Yankee related to its proposed 20%
power uprate. NRC responded on May 4, 2004, stating it would perform a new engineering assessment inspection at Vermont Yankee. In its May 4, 2004, letter, NRC also identified that its power uprate review consisted of a comprehensive assessment of engineering, design and safety analyses comprising about 4000 staff-hours.
l The PSB created the term, independentengineering assessment, which it defined within its March 15, 2004 request as a level of effort of four persons for four weeks.
CATEMPTEPU coml.wpd 1
Richard Ennis, Project Manager June 8, 2004 Also, in December 2003, the NRC issued Revision 0 of RS-001. In response to comments from the Advisory Committee on Reactor Safeguards (ACRS), NRC included the following statement regarding independent calculations:
Perform audits and/orindependent calculationsas deemed necessary and appropriateto support review of the licensee's application. In determining the needforperforming auditsand/or independent calculations, considerthe following:
- confidence of the NRC staff in the models and/ormethods used by the licensee
- confidence of the NRC staff in the analysis results
- familiarityof the NRC staff with the models and/or methods used by the licensee
- prioruse of the models and/ormethodsfor similarplant designs and operating conditions and the NRC staffs experience relatedto such use
- NRC staff experience with the impact ofproposedchanges on analysis results
- availablemargin versus level of uncertainty in analysis results
- efficiency gains that may resultfrom performing audits and/or independent calculations RS-001, Section 2.1, page 2.1-3.
Accordingly, we believe that independent calculations should be performed by NRC as part of the new engineering assessment inspection, together with the power uprate review, in the three areas identified below.
Steam Dryer Analysis Despite licensee and industry analysis, significant, power uprate related failures of steam dryers have occurred at four units - Quad Cities 1 & 2 and Dresden 2 & 3.Of three types of steam dryers, square, curved and slanted, Vermont Yankee has the same squared-design steam dryer as Quad Cities and Dresden, determined to be the most susceptible to power uprate related cracking.
In NRC's letter of May 4, 2004, it was stated that outside technical experts are assisting NRC staff on steam dryer issues. In addition, we are aware that Entergy has performed an analysis of its steam dryer and has completed modifications for power uprate in its Spring 2004 refueling outage. In addition, Entergy discovered and dispositioned numerous cracks in the steam dryer.
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Richard Ennis, Project Manager June 8, 2004 We believe the analysis for the adequacy of the steam dryer meets the criteria for independent calculation stated in RS-001, Section 2.1. Therefore, we request that NRC verify by independent calculation the adequacy of Vermont Yankee's steam dryer, with modifications, for power uprate as part of its new engineering assessment inspection, together with the power uprate review. Further, we request that Vermont Yankee not be allowed to operate above original licensed thermal power (OLTP) until the NRC verification analysis of the steam dryer is completed.
Credit for Containment Overpressure Centrifugal pumps required to perform safety actions must have adequate NPSH in order to function properly. For power uprate situations, available NPSH is reduced because water temperatures are warmer than at original power because more heat is produced in the reactor. To compensate for decreased NPSH because of hotter water temperatures, Entergy requests credit for the elevated pressure in containment (containment overpressure). In Section 4.2.6 of the Safety Analysis Report for Vermont Yankee Nuclear Power Station ConstantPressurePower Uprate (PUSAR), NEDC-33090, September 2003, Entergy requests containment overpressure credit for either one or two sets of pumps for four different situations:
- On loss of coolant accidents (LOCAs), for the residual heat removal (RHR) and core spray (CS) pumps a On an anticipated transient without scram (ATWS), for the RHR pumps
- On Appendix R fire events, for the RHR and CS pumps In our letter of December 8, 20032, we asked NRC questions about granting containment overpressure credit, which represents both a change in Vermont Yankee's design basis and a change in NRC's regulatory policy. It does not appear that granting containment overpressure credit is necessary in the context of Draft Regulatory Guide DG 1107, at 7, and it appears that the design can be practicablyalteredin the context of DG 1107, at 16, by operation at OLTP. Therefore, pending response to our December 8, 2003 letter, we do not believe containment overpressure credit should be allowed.
Notwithstanding, and without waiving our belief that containment overpressure credit should not be allowed, if such credit is allowed, we believe the NRC should perform the following independent calculations.
2 We are awaiting response to our letter of December 8, 2003.
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Richard Ennis, Project Manager June 8, 2004 The four situations for which containment overpressure credit is requested are fundamentally different. Two situations, LOCA and ATWS pressurize the drywell first and then the torus. The othet situations, SBO and Appendix R events, pressurize only the torus. The analysis of each situation consists of a containment response analysis and an NPSH calculation. Finally, the single failure criteria effects are not the same for each situation.
Because of the importance of the RHR and CS pumps for the situations in question, and because of the controversial nature of the change in NRC's regulatory policy, we believe these situations meet the requirements of RS-001, Section 2.1 for independent calculations. Therefore, we request that NRC verify by independent calculation the adequacy of the claimed containment overpressure credit for power uprate as part of its new engineering assessment inspection, together with the power uprate review. The containment response for each situation where credit is requested should be independently verified by NRC analysis. A single failure mode and effects analysis should be performed by NRC for each situation and sufficient calculations should be performed to assure the most limiting single failure is identified 3. The water temperature and available NPSH should be determined for each situation, again assuming the most limiting single failure, to verify the calculated containment overpressure provides sufficient NPSH.
Flow-Induced Vibration Adequacy In PUSAR Section 3.4.1, it is stated that Entergy will demonstrate the adequacy of increased flow-induced vibration of the main steam system and feedwater system piping only through a piping startup testing program. However, since power uprate related, vibration failures have occurred for an electromatic releif valve, small piping in main steam and feedwater lines, and a feedwater instrument probe, we believe the flow-induced adequacy of the main steam and feedwater lines, including branch lines connected to the main steam and feedwater systems, should be confirmed by analysis wherever possible.
3 With regard to the single failure mode and effects analysis, we believe the guidance from Regulatory Guide 1.183, Section C.5.1.4, albeit for a different subject - alternative source tenn, is sound and should be applied for the review of containment overpressurecredit. In summary, Section C.5.1.4 states that, since a request for alternativesource ternz is a change to a plant's historical licensing basis, the review of its adequacy may consider current, rather than historical, licensing requirements for other affected aspects of the request. Since containment overpressure credit is a change to Vermont Yankee's historical licensing basis, its adequacy should be evaluated using the single failure criteria applicable to current-day license evaluations.
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Richard Ennis, Project Manager June 8, 2004 Since failures have occurred in this area, we believe the area of flow-induced vibrations meet the requirement of RS-001, Section 2.1 for independent calculations. Therefore we request that NRC verify by independent calculation the adequacy of increased flow-induced vibration of the main steam and feedwater systems, including branch lines, as part of its new engineering assessment inspection, together with the power uprate review.
Conclusion RS-001, Section 2.1 identifies either audits or independent calculations as appropriate actions for the conditions identified on page 2.1-3. We believe that independent calculations by the NRC should be performed for the three areas identified above.
However, we would be pleased to discuss with the NRC whether audits of any of these areas is more appropriate than independent calculations. We welcome the opportunity to provide these comments and look forward to resolving these issues in a satisfactory manner. If you have questions about these items, please call me at 802-828-2321, or Mr.
William Sherman of my staff at 802-828-3349.
Sincerely, David O'Brien, Commissioner State Liaison Officer cc: Mario V. Bonaca, Chairman, ACRS J. Thayer, Entergy Sen. Patrick Leahy Sen. James Jeffords Rep. Bernard Sanders C:\TEMP\EPU coml.wpd 5
June 9, 2004 RE: Vermont Yankee Nuclear Power Station License No. DPR-28 (Docket No. 50-271)
Technical Specification Proposed Change No. 262 Alternate Source Tern - State of Vermont Comments Richard Ennis, Project Manager U.S. Nuclear Regulatory Commission Washington, D.C., 20555
Dear Mr. Ennis,
The state of Vermont is asked to comment on Vermont Yankee's alternate source term (AST) proposal. We believe the AST proposal should not be approved without modifications for the following reasons:
- 1. The standby liquid control (SLC) system does not appear to meet the single failure criteria appropriate for a system used to mitigate the consequences of a design basis accident ("an engineered safety feature system").
- 2. The main steam isolation valve (MSIV) alternate leakage treatment (ALT) pathway does not appear to meet the quality standards appropriate for a system used to mitigate the consequences of a design basis accident ("an engineered safety feature system").
- 3. There is no reason to reduce safety margins for Vermonters by doubling the amount of allowed leakage from MSIV's from the leakage levels Vermont Yankee has met for the past 32 years.
Background
On August 8, 2003, we asked the NRC a series of questions regarding Vermont Yankee's AST proposal. The NRC staff responded on December 16, 2003. In that letter, NRC defers a number of responses by stating it "will address the adequacy of the licensee's request in our final SE [safety evaluation]". On May 12 and 13, 2004, we were provided C:\TEMP\AST comi .wpd l
Richard Ennis, Project Manager June 9, 2004 by email information on the NRC's proposed final SE of the SLC system single failure and AST quality assurance design.
SLC System Single Failure As part of the AST proposal, the function of the Vermont Yankee standby liquid control (SLC) system would be modified. In its original design, the SLC system was provided as a backup system to provide negative reactivity to the reactor core in the event of beyond-design-basis events. As such, the SLC system was an auxiliary supporting system. For AST, the SLC function is changed to provide pH control for the suppression pool after design basis accidents. Therefore, the SLC becomes an engineered safety feature (ESF) system.
The SLC system is not fully redundant. Portions of the SLC piping are not redundant, and two non-redundant active check valves are located on the containment penetration for the system.
Regarding single failure, Vermont Yankee's ESF design criteria is stated in Section 1.5.6 (4) of its Final Safety Analysis Report:
Essential safety actions shall be carried out by redundant and independent equipment so that no single failure of an active component can prevent required actions.
The current NRC single failure criteria is stated in 10 CFR 50, Appendix A as:
Single failure. A single failure means an occurrence which results in the loss of capability of a component to perform its intended safety functions.
Multiple failures resulting from a single occurrence are considered to be a single failure. Fluid and electric systems are considered to be designed against an assumed single failure if neither (1) a single failure of any active component (assuming passive components function properly) nor (2) a single failure of a passive component (assuming active components function properly), results in a loss of the capability of the system to perform its safety functions.
NRC claims that it is acceptable for an application not to meet the single failure criteria if acceptable quality and reliability of the non-redundant component can be shown. It's claims are based on guidance contained in Regulatory Guide 1.53, "Application of the C:\TEMP\AST corn!.wpd 2
Richard Ennis, Project Manager June 9, 2004 Single-Failure Criterion to Nuclear Power Plants Protection Systems." December 16 letter, Response 3(b).
We disagree with this interpretation of single failure for four reasons. First, it is contrary both to the plain statement of Vermont Yankee's design and licensing basis and the NRC's regulation. Second, it is contrary in practice to Vermont Yankee's design of engineered safety feature system. We do not know of other cases in which Vermont Yankee ESF systems were licensed with non-redundant active components. Third, if NRC is changing Vermont Yankee's licensing basis based on new interpretations, it should not grant this change piecemeal. Section C.5.1.4 of Regulatory Guide 1.183 (quoted below) states that current-day licensing standards will be used for the AST review:
5.1.4 Applicability of PriorLicensing Basis The NRC staff considers the implementation of an AST to be a significantchange to the design basis of thefacility that is voluntarily initiatedby tile licensee. In orderto issue a license amendment authorizing the use of an AST and tile TEDEdose criteria,the NRC staff must make a currentfinding of compliance with regulationsapplicable to the amendment. The characteristicsof the ASTs and the revised dose calculational methodology may be incompatible with many of the analysis assumptionsand methods currently reflected in the facility's design basis analyses. The NRC staffmay find that new or unreviewed issues are created by a particularsite-specific implementation of the AST, warrantingreview of staffpositions approvedsubsequent to the initialissuance of the license. This is not considereda backfit as defined by 10 CFR 50.109, "Backfitting. "
However, priordesign bases that are unrelatedto the use of the AST, or are unaffected by the AST, may continue as thefacility's design basis. Licensees should ensure that analysis assumptions and methods are compatible with the ASTs and the TEDE criteria.
We believe that, if any part of new licensing bases are used, the complete applicable new licensing basis should be used. If NRC is applying a less-stringent, current-day single failure criteria, it should invoke all applicable current-day licensing bases, including but not limited to single passive failure design and current seismic design requirements.!
Fourth, Vermont Yankee has not demonstrated the non-redundant check valves meet the NRC's current-day requirement for quality and reliability. Similar check valves have failed to open in five other similar applications in the industry. Entergy February 25, 2004 letter to NRC, Response to RAI No. 4(a)(2).
Therefore, we believe that, in order to approve the AST proposal, NRC should require the new Vermont Yankee ESF SLC system to meet the single failure criterion.
We note that Entergy, in its February 25, 2004 Response to Request for Additional Information, Response to RAI No. I (b), states it does not meet current-day seismic design requirements but reverts to its earlier, less stringent original licensing basis.
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Richard Ennis, Project Manager June 9, 2004 MSIV Alternate Leakage Treatment (ALT) Pathway In conjunction with, but unrelated to, its AST proposal, Vermont Yankee requests to double its allowable individual MSIV leakage of 31 standard cubic feet per hour as part of an alternate leakage treatment pathway. The ALT pathway includes piping and valves to the main condenser which were neither designed nor purchased to safety-related system requirements. Because the intended use of the ALT pathway is to mitigate the consequences of a design basis accident, it is an engineered safety feature. NRC letter of December 16, 2003, Response 2(a).
Vermont Yankee has performed analysis demonstrating the ALT piping and valves, including the condenser, are seismically rugged. However, this analysis is neither the same evaluation for ESF systems in Vermont Yankee's current licensing basis, nor is it the seismic analysis that would be required for ESF systems under NRC's current-day seismic requirements. In addition, since the ALT piping and values, including the condenser, were not purchased under an 10 C.F.R. 50, Appendix B quality assurance program, confidence in current seismic analysis is uncertain since material properties and weld techniques are uncertain.
The issues of seismic and quality assurance design of the ALT pathway were questioned in our August 8, 2003 letter. NRC's response was that the issues would be addressed in the final SE. NRC letter of December 16, 2003, Responses 2(e) and 2(f). In an email of May 13, 2004, NRC identified its intent to approve the seismic and quality assurance portions of the ALT pathway based on footnotes and exceptions from two Standard Review Plan (SRP) Revision 2 Drafts from 1996 (SRP 3.2.1, "Seismic Classification",
and SRP 3.2.2, "System Quality Group Classification").
We disagree with NRC's evaluation for three reasons. First, we do not believe unapproved, draft SRPs should be used as the basis for approval of Vermont Yankee's proposed ALT. Why are the SRP's still in draft form from 1996? What is NRC's policy on using draft information for its review standard? We note that these draft SRP's are neither referred to in the Regulatory Standard for Power Uprate (RS-001) nor available in the NRC's SRP collection on its website. Second, we believe that Vermont Yankee's original ESF licensing basis should be invoked for the ESF ALT pathway. This would include Seismic Class I design and analysis and purchase to a 10 C.F.R. 50, Appendix B, quality assurance program. Third, we see no reason to allow Vermont Yankee twice as much leakage through its MSIV's. In its AST amendment request of July 31, 2003, it states that maintaining the current limit would cause unnecessary maintenance. However, Vermont Yankee has been able to maintain these MSIV's to the current limit for the last 32 years. Doubling the allowable leakage would mean potentially exposing Vermonters C:\TEMP\AST coml.wpd 4
Richard Ennis, Project Manager June 9, 2004 to twice as much radioactive leakage from MSIV's in the event of a design basis loss-of-coolant accident. Based on past successful maintenance history, exposing Vermonters to this increased potential is unnecessary and undesirable.
We do not believe the request for increased MSIV leakage should be granted. If the increase MSIV leakage is granted, we would like NRC to provide a presentation of the increased risks to Vermonters from the increased MSIV leakage and the issues concerning whether Vermonters should be subject to this increased risk.
Conclusion We welcome the opportunity to provide these comments and look forward to resolving these issues in a satisfactory manner. If you have questions about these items, please call me at 802-828-2321, or Mr. William Sherman of my staff at 802-828-3349.
Sincerely, David O'Brien, Commissioner State Liaison Officer cc: J. Thayer, Entergy Sen. Patrick Leahy Sen. James Jeffords Rep. Bernard Sanders C:\TEMP\AST coml.wpd 5