ML042990452
| ML042990452 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 10/27/2004 |
| From: | Richard Guzman NRC/NRR/DLPM/LPD1 |
| To: | Vanderheyden G Calvert Cliffs |
| Guzman R, NRR/DLPM 415-1030 | |
| References | |
| TAC MC3595, TAC MC3596 | |
| Download: ML042990452 (4) | |
Text
October 27, 2004 Mr. George Vanderheyden, Vice President Calvert Cliffs Nuclear Power Plant, Inc.
Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702
SUBJECT:
CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 -
REQUEST FOR ADDITIONAL INFORMATION RE: LICENSE AMENDMENT REQUEST TO USE ALTERNATE DECAY HEAT REMOVAL IN MODE 6 REFUELING (TAC NOS. MC3595 AND MC3596)
Dear Mr. Vanderheyden:
In reviewing your submittal of June 7, 2004, concerning the subject request for amendment to incorporate the use of an alternate cooling method to function as a path for decay heat removal when in Mode 6 with the refueling pool fully flooded, the Nuclear Regulatory Commission (NRC) staff has determined that additional information contained in the enclosure to this letter is needed to complete its review. The NRC staff discussed the issue with your staff on September 20, 2004. As agreed to by your staff, we request you respond within 30 days of the date of this letter.
If you have any questions, please contact me at 301-415-1030.
Sincerely,
/RA/
Richard V. Guzman, Project Manager, Section 1 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318
Enclosure:
As stated cc w/encl: See next page
ML042990452 OFFICE PDI-1/PM PDI-1/LA SRXB/SC PDI-1/SC NAME RGuzman SLittle JUhle RLaufer DATE 10/25/04 10/25/04 10/25/04 10/27/04
Enclosure REQUEST FOR ADDITIONAL INFORMATION (RAI) CONCERNING AMENDMENT REQUEST TO INCOPORATE THE USE OF AN ALTERNATE COOLING METHOD TO FUNCTION AS A PATH FOR DECAY HEAT REMOVAL WHEN IN MODE 6 REFUELING CALVERT CLIFFS NUCLEAR POWER PLANT (CCNPP), UNIT NOS. 1 AND 2 DOCKET NOS. 50-317 AND 50-318
- 1.
In the RAI responses for WCAP-15872, response C1 states,... good agreement between fluid temperatures based on the computational fluid dynamics (CFD) analysis and the Calvert Cliffs test data at the reactor vessel flange elevation was predicted assuming a natural circulation path with down-flow in the center of the core and up-flow at the core periphery. This flow pattern was found to best represent the post-refueled conditions, where fresh fuel occupies a checkerboard arrangement in the core center, which existed during the alternate heat removal test phase at Calvert Cliffs.
The comparison of the consistency of the CCNPP Unit 2 test data with CFD predictions, for the demonstration of the application of a one-dimensional model in conjunction with a multidimensional CFD calculation, is for post-refueled conditions. At issue to the technical specification change request for CCNPP are the pre-refueled conditions.
Provide the justification that for the limiting pre-refueled conditions at CCNPP, the appropriate CFD computed bypass and mixing coefficients correctly predict the refueling pool fluid temperature with sufficient margin so as to preclude exceeding the CCNPP operating limit of 140 oF. Specifically, are the CFD computed bypass and mixing coefficients sensitive to the core fuel arrangement and/or the concomitant flow pattern during natural circulation?
- 2.
You state, A minimum decay heat value of ~ 3.0 MW is also required to maintain enough natural circulation to provide sufficient mixing of borated coolant to minimize the effects of boron dilution accident and to prevent boron stratification.
- a.
How do you arrive at a minimum decay heat value of ~ 3.0 MW? What is the maximum keff of the CCNPP core under these conditions? What is the worth of the boron that is subject to potential dilution and/or stratification? What is the keff of the CCNPP core at a decay heat value of 2.0 MW?
b.
How do you assure that this minimum decay heat load is maintained during refueling under the alternate heat removal alignment? What do you compute and/or measure?
- 3.
You propose to use the spent fuel cooling loop in lieu of a shutdown cooling loop. The spent fuel pool is designed to maintain keff < 1.0 without boron and at optimum moderation. What is your defense-in-depth for a dilution accident with a fluid at those conditions?
Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 cc:
President Calvert County Board of Commissioners 175 Main Street Prince Frederick, MD 20678 James M. Petro, Esquire Counsel Constellation Energy 750 East Pratt Street, 17th floor Baltimore, MD 21202 Jay E. Silberg, Esquire Shaw, Pittman, Potts, and Trowbridge 2300 N Street, NW Washington, DC 20037 Lou Larragoite Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702 Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 287 St. Leonard, MD 20685 Mr. R. I. McLean, Administrator Radioecology Environ Impact Prog Department of Natural Resources Nuclear Evaluations 580 Taylor Avenue Tawes State Office Building Annapolis, MD 21401 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Kristen A. Burger, Esquire Maryland People's Counsel 6 St. Paul Centre Suite 2102 Baltimore, MD 21202-1631 Patricia T. Birnie, Esquire Co-Director Maryland Safe Energy Coalition P.O. Box 33111 Baltimore, MD 21218 Mr. Loren F. Donatell NRC Technical Training Center 5700 Brainerd Road Chattanooga, TN 37411-4017