ML12166A192
| ML12166A192 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 06/21/2012 |
| From: | Nadiyah Morgan Plant Licensing Branch 1 |
| To: | George Gellrich Calvert Cliffs |
| Morgan N | |
| References | |
| TAC ME7672, TAC ME7673 | |
| Download: ML12166A192 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 21, 2012 Mr. George H. Gellrich, Vice President Calvert Cliffs Nuclear Power Plant, LLC 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 REGARDING REALISTIC LARGE BREAK LOSS-OF-COOLANT-ACCIDENT ANALYSIS (TAC NOS.
ME7672 AND ME7673)
Dear Mr. Gellrich:
By letter dated December 1, 2011, Calvert Cliffs Nuclear Power Plant, LLC submitted an Emergency Core Cooling System evaluation of once-and twice-burned AREVA fuel at Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2. The evaluation addresses the specific thermal conductivity degradation issues identified by the Nuclear Regulatory Commission (NRC) staff.
The NRC staff is reviewing the submittals and has determined that additional information is needed to complete its review. The specific questions are found in the enclosed request for additional information (RAI). The NRC staff is requesting a response to the RAI within 30 days of receipt.
If you have any questions regarding this issue, please contact me at (301) 415-1016.
Nadiyah S. Morgan, Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318
Enclosure:
Request for Additional Information cc w/encl: Distribution via Listserv
REQUEST FOR ADDITIONAL INFORMATION CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 REALISTIC LARGE BREAK LOSS-OF-COOLANT-ACCIDENT ANALYSIS DOCKET NOS. 50-317 AND 50-318 By letter dated December 1, 20111, Calvert Cliffs Nuclear Power Plant, LLC requested approval of the realistic large break loss-of-coolant-accident (LBLOCA) analysis for Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 (Calvert Cliffs).
In order to complete the review, the Nuclear Regulatory Commission (NRC) staff requests further information on the following items:
- 1. Please show the results for the limiting downcomer boiling case for Calvert Cliffs. Please identify the limiting parameters for this case in a data table. See the requested list of data parameters for all of the LBLOCA case runs.
- 2. Figure 3-19 shows a decreasing downcomer liquid level, while the core levels are increasing after about 325 seconds.
- a. Please explain why the core levels are increasing while the downcomer levels show a dramatic decrease.
- b. The average trends of the core and downcomer liquid levels show a decreasing average inventory over the last 150 seconds. Provide results of this limiting break beyond 300 sec until the levels show a steadily increasing trend.
- 3. Fig. 3-3 shows only four azimuthal sectors for a four loop plant. NRC staff calculations for a combustion engineering plant showed that use of 8 azimuthal sectors in the downcomer (an azimuthal downcomer volume in between each cell connected to each cold leg) increase peak cladding temperature (PCT) by as much as 400 degrees Fahrenheit (OF). While the four azimuthal sectors may be converged as stated in section 4.5.2.1, the additional azimuthal sectors have been shown to produce more downcomer boiling, since the injected emergency core coolant (ECC) is no longer averaged over the entirety of only four cells, thereby reducing the driving head and increasing PCT. If the refueling water storage tank (RWST) temperature is at a maximum with the increased nodalization, PCT is expected to show an increase relative to the crude downcomer nodalization scheme.
- a. Show the results of the more detailed downcomer on ECC response for Calvert Cliffs.
- b. What RWST/safety injection tank (SIT) temperatures, decay heat multiplier, and planar linear heat generation rate (PLHGR) were used in the 3-loop sensitivity study?
-2
- 4. Tabulate the statistically sampled conditions, input data, etc. for the following parameters for all of the sampled break sizes. A data file is preferred for transmitting the data.
Case end time PCT elevation Hot rod Assembly burnup Core power (Mwt)
PLHGR (kw/ft)
Axial skew Axial shape index Break type One sided break size (ft2)
Tmin CF)
Initial stored energy rF)
Decay heat multiplier Film boiling heat transfer coefficient (HTC) (btu/hr/WrF)
Dispersed flow film boiling HTC Condensation interphase HTC Initial reactor coolant system Flow rate (Mlbs/hr)
Initial Tcold (OF)
Pressurizer pressure (psia)
Pressurizer level (ft)
SIT pressure (psia)
SIT liquid volume (ft3)
Start of broken loop SIT injection (seconds)
Start of intact loop SIT injection (seconds)
Broken loop SIT empty time Intact loop SIT empty time Start of high pressure safety injection flow Start of low pressure safety injection flow Beginning of refill time End of refill time/start of reflood Beginning of bypass time Time of annulus downflow/end of bypass Reflood rate up to time of PCT Containment pressure at time of PCT Containment volume (ft3)
June 21,2012 Mr. George H. Gellrich, Vice President Calvert Cliffs Nuclear Power Plant, LLC 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 REGARDING REALISTIC LARGE BREAK LOSS-OF-COOLANT-ACCIDENT ANALYSIS (TAC NOS.
ME7672 AND ME7673)
Dear Mr. Gellrich:
By letter dated December 1, 2011, Calvert Cliffs Nuclear Power Plant, LLC submitted an Emergency Core Cooling System evaluation of once-and twice-burned AREVA fuel at Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2.. The evaluation addresses the specific thermal conductivity degradation issues identified by the Nuclear Regulatory Commission (NRC) staff.
The NRC staff is reviewing the submittals and has determined that additional information is needed to complete its review. The specific questions are found in the enclosed request for additional information (RAI). The NRC staff is requesting a response to the RAI within 30 days of receipt.
If you have any questions regarding this issue, please contact me at (301) 415-1016.
Sincerely, IRA!
Nadiyah S. Morgan, Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318
Enclosure:
Request for additional Information cc w/encl: Distribution via Listserv DISTRIBUTION:
PUBLIC LPLI-1 rlf RidsNrrDorlLpLl-1 RidsNrrPMCalvertCliffs LWard, NRR RidsNrrDssSnpb RidsOgcMailCenter RidsNrrLAKGoldstein RidsAcrsAcnwMailCenter RidsRegion1 MailCenter ADAMS ACCESSION NO: ML12166A192 i OFFICE LPLI-1/PM LPLI-1/LA SNPB/BC LPLI-1/BC i
NAME NMorgan KGoldstein AMendiola GWilson DATE 6/15/12 6/14/12 6/18/12 6/21/12 I:
OFFICIAL RECORDS COpy I