ML031390039
| ML031390039 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 05/21/2003 |
| From: | Pulsifer R NRC/NRR/DLPM/LPD1 |
| To: | Thayer J Entergy Nuclear Vermont Yankee |
| Pulsifer R M, NRR/DLPM, 415-3016 | |
| References | |
| TAC MB8070 | |
| Download: ML031390039 (7) | |
Text
May 21, 2003 Mr. Jay K. Thayer Site Vice President - Vermont Yankee Entergy Nuclear Vermont Yankee, LLC P.O. Box 0500 185 Old Ferry Road Brattleboro, VT 05302-0500
SUBJECT:
VERMONT YANKEE NUCLEAR POWER STATION - REQUEST FOR ADDITIONAL INFORMATION RE: ARTS/MELLLA (TAC NO. MB8070)
Dear Mr. Thayer:
The Nuclear Regulatory Commission (NRC) staff is reviewing Entergys application dated March 20, 2003, regarding implementation of the Average Power Range Monitor, Rod Block Monitor Technical Specifications/Maximum Extended Load Line Limit Analysis (ARTS/MELLLA).
In order for the staff to complete its review, further clarification is required of several items. As agreed with your staff, your prompt response to this request within 30 days would help the staff meet its schedule for completion of this review. If there are any questions, please call me at (301) 415-3016.
Sincerely,
/RA/
Robert M. Pulsifer, Project Manager, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-271
Enclosures:
Request for Additional Information cc w/encls: See next page
Vermont Yankee Nuclear Power Station cc:
Regional Administrator, Region I U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Mr. David R. Lewis Shaw, Pittman, Potts & Trowbridge 2300 N Street, N.W.
Washington, DC 20037-1128 Ms. Christine S. Salembier, Commissioner Vermont Department of Public Service 112 State Street Montpelier, VT 05620-2601 Mr. Michael H. Dworkin, Chairman Public Service Board State of Vermont 112 State Street Montpelier, VT 05620-2701 Chairman, Board of Selectmen Town of Vernon P.O. Box 116 Vernon, VT 05354-0116 Mr. Michael Hamer Operating Experience Coordinator Entergy Nuclear Vermont Yankee, LLC P.O. Box 250 Governor Hunt Road Vernon, VT 05354 G. Dana Bisbee, Esq.
Deputy Attorney General 33 Capitol Street Concord, NH 03301-6937 Chief, Safety Unit Office of the Attorney General One Ashburton Place, 19th Floor Boston, MA 02108 Ms. Deborah B. Katz Box 83 Shelburne Falls, MA 01370 Mr. Raymond N. McCandless Vermont Department of Health Division of Occupational and Radiological Health 108 Cherry Street Burlington, VT 05402 Mr. Gautam Sen Manager, Licensing Entergy Nuclear Vermont Yankee, LLC P.O. Box 0500 185 Old Ferry Road Brattleboro, VT 05302-0500 Resident Inspector Vermont Yankee Nuclear Power Station U. S. Nuclear Regulatory Commission P.O. Box 176 Vernon, VT 05354 Director, Massachusetts Emergency Management Agency ATTN: James Muckerheide 400 Worcester Rd.
Framingham, MA 01702-5399 Jonathan M. Block, Esq.
Main Street P.O. Box 566 Putney, VT 05346-0566 Mr. Michael R. Kansler Sr. Vice President and Chief Operating Officer Entergy Nuclear Operations, Inc.
Mail Stop 12A 440 Hamilton Ave.
White Plains, NY 10601 Mr. John J. Kelly Director, Licensing Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 1060
May 21, 2003 Mr. Jay K. Thayer Site Vice President - Vermont Yankee Entergy Nuclear Vermont Yankee, LLC P.O. Box 0500 185 Old Ferry Road Brattleboro, VT 05302-0500
SUBJECT:
VERMONT YANKEE NUCLEAR POWER STATION - REQUEST FOR ADDITIONAL INFORMATION RE: ARTS/MELLLA (TAC NO. MB8070)
Dear Mr. Thayer:
The Nuclear Regulatory Commission (NRC) staff is reviewing Entergys application dated March 20, 2003, regarding implementation of the Average Power Range Monitor, Rod Block Monitor Technical Specifications/Maximum Extended Load Line Limit Analysis (ARTS/MELLLA).
In order for the staff to complete its review, further clarification is required of several items. As agreed with your staff, your prompt response to this request within 30 days would help the staff meet its schedule for completion of this review. If there are any questions, please call me at (301) 415-3016.
Sincerely,
/RA/
Robert M. Pulsifer, Project Manager, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-271
Enclosures:
Request for Additional Information cc w/encls: See next page DISTRIBUTION:
PUBLIC RPulsifer CRaynor FArner, RI PDI-2 R/F FAkstulewicz CAnderson, RI EKendrick CHolden JClifford JBobiak, RI HGarg ADAMS Accession Number: ML031390039
- See previous concurrence.
OFFICE PDI-2/PM PDI-2/LA SRXB*
EEIB*
PDI-2/SC NAME RPulsifer CRaynor FAkstulewicz EMarinos JClifford DATE 5/21/03 5/21/03 5/20/03 5/20/03 5/21/03 OFFICIAL RECORD COPY
REQUEST FOR ADDITIONAL INFORMATION (RAI)
ARTS/ MELLLA IMPLEMENTATION General Discussion It is not clear to the NRC staff, from the licensees March 20, 2003 submittal regarding implementation of the Average Power Range Monitor, Rod Block Monitor Technical Specifications/Maximum Extended Load Line Limit Analysis (ARTS/MELLLA) how Vermont Yankee Nuclear Power Station (VYNPS) achieved the current thermal analysis basis, Extended Load Line Limit Analysis (ELLLA) from their original licensing basis.
Related to the above, it is not clear how the implementation of the proposed partial ARTS improvement interacts with the proposed MELLLA implementation to replace the current ELLLA power flow map, with the increased core flow (ICF) condition.
The following questions will help the staff evaluate the ARTS/MELLLA submittal:
- 1), Supporting Information and Safety Assessment Page 11, second paragraph:
The maximum standby liquid control system (SLCS) pump discharge pressure during the limiting anticipated trip without scram (ATWS) event is 1320 pounds per square inch gage (psig). The pressure regulator failure - open (PRFO) event was identified as the limiting event in Section 9.3 of the ARTS/MELLLA safety analysis report (A/MSAR), as giving a peak reactor pressure vessel (RPV) bottom pressure of 1367 psig at 38.9 sec decreasing to 1290 pounds per square inch absolute (psia) at the time of SLCS initiation (152.7 sec). Confirm the units of psig and psia and the delta psi pump margin available.
- 2), Determination of No Significant Hazards Discuss how the ARTS changes improve plant instrumentation and accuracy. Is this primarily due to the flow control trip reference (FCTR) card upgrade?
- 3), GENE Report NEDC-33089P (A/MSAR)
Section 1.0 Introduction A limited discussion of the VYNPS currently licensed APRM, RBM and ELLLA operating map restrictions is provided. Please elaborate with regard to the proposed partial implementation of the ARTS improvements in conjunction with the proposed MELLLA operating map. Specifically, why is the partial ARTS implementation required, and why is it complementary to the MELLLA mode?
It is stated that the VYNPS ARTS application will not include modification from a flow to a power dependent system and, therefore, the existing RBM setpoint is relaxed so that interference when in MELLLA can be avoided or minimized. The current ELLLA boundary corresponds to the 108% APRM Rod Block setpoint. ARTS/MELLLA expands the domain along the 120.8% rod line. Does this removal of interference contribute to unintended operation above the MELLLA line? Would the operational flexibility resulting from the new RBM setpoints allow operation above the MELLLA line?
Please provide references for the bases for the current APRM/RBM/ELLLA restrictions.
Since VYNPS has been previously analyzed for ELLLA/ICF, is the implementation of MELLLA equivalent to the Maximum Extended Operating Domain (MEOD)? Are there other implications to this combination?
4)
Section 1.2.2, APRM High Flux (Flow Bias) Scram and Rod Block Design Bases Analytical limit calculations were performed using current GE ARTS/MELLLA methodology. Please provide the methodology reference?
5)
Section 1.3, APRM Improvements Please provide a reference to the original minimum critical heat flux ratio (MCHFR) thermal limits and the current General Electric Thermal Analysis Basis (GETAB) basis.
6)
Section 3.1, Limiting Core-Wide Anticipated Operational Occurrence (AOO) Analyses Loss-of-feedwater heating (LFWH)/High Pressure Coolant Injection (HPCI) were not analyzed at the MELLLA conditions. What is the basis for the conclusion that there is a large margin to other events? LFWH/HPCI can occur at normal power operations. Why is this event not considered in the determination and validation of the off-rated limits?
It is stated IRLS [idle recirculation loop startup] and RFI [recirculation flow increase]
events were not considered for the MELLLA application. Please discuss the AOO analyses conclusions and confirm that they are based on actual plant-specific MELLLA analyses.
It is stated that extensive transient analyses were performed during the original development of the ARTS improvement program and that these evaluations are applicable to MELLLA operation. Please provide a reference to these analyses and how it was confirmed they were applicable to MELLLA.
As discussed with Entergy at a meeting on April 29, 2003, it would be useful to construct a table showing the events and the dependence on generic, plant specific, or reload evaluations and analyses.
There is a reference to the GEXL-PLUS correlation. Confirm that this correlation is valid over the range of power/flow conditions for the ARTS/MELLLA/ICF operating map.
7)
Section 5.0, Thermal-Hydraulic Stability Please describe the calculation used to obtain the procedure core decay ratio, and provide the Cycle 23 conditions including core design, power level, axial power shape, and other relevant parameters.
Also, clarify that the results in the report are conservative and generic in nature, based on the approved Boiling Water Reactor Owners Group position, and will be revised on a cycle-specific basis.
8)
Section 9.0, Anticipated Transient Without Scram The maximum SLCS pump discharge pressure during the limiting ATWS event is 1320 psig. Main steam isolation valve closure (MSIVC) and PRFO events were re-evaluated and PRFO was identified as the limiting event, giving a peak RPV bottom pressure of 1367 psig at 38.9 sec decreasing to 1290 psia at the time of SLCS initiation (152.7 sec).
It was stated that LOOP and inadvertent opening of a relief valve (IORV) were considered but found to be non-limiting. How were they considered, and how were they determined to be non-limiting?
Table 9-2 Please discuss why the peak neutron flux is substantially higher at the end-of-cycle for the PRFO event.
9)
Technical Specification (TS) Section 2.1.A.1.a, Limiting Safety System Setting for Fuel Cladding Integrity has listed the neutron flux trip setting for APRM flux scram trip setting (run mode) as:
Two Loop Operation S0.4W + 64.4% for 0% < W 31.1%
S1.28W + 37.0% for 31.1% < W 54.0%
S0.66W + 70.5% for 54.0% < W 75.0%
With a maximum of 120.0% power for W > 75.0%
Single Loop Operation S0.4W + 61.2% for 0% < W 39.1%
S1.28W + 26.8% for 39.1% < W 61.9%
S0.66W + 65.2% for 61.9% < W 83.0%
With a maximum of 120.0% power for W > 83.0%
The licensee has also listed the same equations in TS Table 3.1.1, Reactor Protection System (Scram) Instrument Requirements, and for Function 4, APRM High Flux (flow bias) trip setting. The licensees justification for these changes is based on GE Report NEDC-33089, Section 1.2.2. However, the GE Report lists these values as an analytical limit. Based on this, the staff is unable to determine whether these values have been calculated as an analytical limit, Trip setting, or limiting safety system setting and raises the question how the instrument uncertainties have been accounted for. This issue further raises the question about the instrument setpoint methodology used by the licensee. Therefore, in order for the staff to determine the adequacy of the setpoint determination, provide the setpoint methodology and calculation performed to determine the trip setpoint and limiting safety system setting, or verify that you used an approved setpoint methodology.
10)
On the bottom of page 10, of Attachment 1, the licensee stated that the physical changes to the plant to accommodate the expanded operating region include FCTR cards and a SSV. GE Report NEDC-33089 provides a reference to GE licensing topical report NEDC -32339P-A, Supplement 2, Revision 1. The staffs acceptance of NEDC -32339P-A, Supplement 2, Revision 1 is based on the licensee meeting certain design and installation guidance. Please confirm that VYNPS meets that guidance. If VYNPS does not meet this guidance, then justify the acceptability of these cards to establish the expanded operating region.