ML19346A122
| ML19346A122 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 05/20/1981 |
| From: | Clark R Office of Nuclear Reactor Regulation |
| To: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| References | |
| NUDOCS 8106050168 | |
| Download: ML19346A122 (7) | |
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UNITED STATES l
8 NUCLEAR REGULATORY COMMISSION o
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Docket Nos.
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3 Mr. A. E. Lundvall, Jr.
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Vice President - Supply SA 4,h-Baltimore Gas & Electric Company P. O. Box 1475 Iyj s
,//g Baltimore, Maryland 21203
Dear Mr. Lundvall:
We have completed our review of the Combustion Engineering (CE) Topical Report CEN-119(B)-P called BASSS (better axial shape selection system).
This November 1979 report, submitted by your letter of June 26, 1980, is for future use of the Incore Detector System to monitor the ONB-LCO fcr Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2.
Based on our review, we conclude that CEN-119(B)-P is ar.ceptable for reference in licensing actions concerning the methodology used to provide an alarm on power when the DNB-LC0 is exceeded for the Calvert Cliffs units. The BASSS is valid for control element assembly (CEA) insertions of CEA Bank 5 from all rods out to 55 percent inserted. Operation of the Calvert Cliffs units with insertions greater than 55 percent of Bank 5 will require monitoring of the DNB-LCO with the excore DNB axial flux offset control limits.
A copy of our topical report evaluation is enclosed.
Sincerely,
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Robert A. Clark, Chief Operating Reactors Branch #3 Division of Licensing
Enclosure:
As stated cc: See next page e
818605o188
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i Baltimore Gas and Electric Company l
cc:
James A. Biddison, Jr.
Ms. Mary Harrison, President Calvert County Board of County Commissioners General Counsel Baltimore Gas and Electric Company Prince Frederick, MD 20768 P. O. Box 1475 Baltimore, MD 21203 U. S. Environmental Protection Agency Region III Office George F. Trowbridge, Esquire Attn: EIS Coordinator Shaw, Pittman, Potts and Trowbridge Curtis Building (Sixth Floor) 1800 M Street, N. W.
Sixth and Walnut Streets Washington, D. C.
20036 Philadelphia, PA 19106 f' ~
Mr. R. C. L. Olson, Principal Engineer Mr. Ralph E. Architzel Nuclear Licensing Analysis Unit Residert Reactor Inspector Baltimore Gas and Electric Company NRC Inspection and Enforcement l
Room 922 - G8E Building P. O. Bos 437 l
P. O. Box 1475 Lusby, MD 20657 Baltimore, MD 21203 Mr. Charles B. Brinkman Manager - Washington Nuclear Operations Mr. Leon B. Russell l
Plant Superintendent Combustion Engineering Inc.
l Calvert Cliffs Nucledar Power Plant 4853 Cordell Avenue, Suite A-1 Maryland Routes 2 & 4 Bethesda,PC 20014 Lusby, MD 20657 Mr. J. A. Tiernan, Manager Bechtel Power Corporation Nuclear Power Department Attn: Mr. J. C. Judd Calvert Cliffs Nuclear Power Plant Chief Nuclear Engineer Maryland Routes 2 & 4 15740 Shady Grove Road Lusby, MD 20657 Gaithersburg, MD 20760 Director, Criteria and Standards Division Combustion Engineering, Inc.
Office of Radiation Programs (ANR-460)
Attn: Mr. P. W. Kruse, Manager U. S. Environmental Protection Agency Engineering Services Washington, D. C.
20460 P. O. Box 500 Windsor, CT 06095 Mr. W. J. Lippold, Supervisor Nuclear Fuel Management Baltimore Gas and Electric Company Public Document Room Calvert Cliffs Nuclear Power Plant Calvert County Library Prince Frederick, MD 20678 P. O. Box 1475 Baltimore, Maryland 21203 Director, Department of State Planning 301 West Preston Street Mr. R. E. Denton, General Supervisor Baltimore, MD 21201 Training & Technical Services Calvert Cliffs Nuclear Power Plant Mr. R. M. Douglass, Manager Maryland Routes 2 & 4 Quality Assurance Department..
Lusby, MD 20657 Fort Smallwood Road Complex P. O. Box 1475 Baltimore, MD. 21203 Mr. T. L. Syndor, General Supervisor Administrator, Power Plant Siting Program Operations Quality Assurance Energy and Coastal Zone Administration Calvert Cliffs Nuclear Power Plant Department of Natural Resources Maryland Routes 2 & 4 Tawes State Office Building Lusby, MD 20657 Annapolis, MD 21204
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' Inclosure TOPICAL REPORT EVALUATION Report
Title:
BASSS, Use of the Incora Detector System to Monitor the DNS-LCO on Calvert Cliffs Unit I and Unit 2 Report Number:
CEN-119(B)-P Report Date:
November 1979 Originating Organization: Combustion Engineering Reviewed By:
Core Performance Branch / Reactor Physics Section Summary of Report This report describes the Better Axial Shape Selection System (BASSS) which uses the fixed rhodium incore detector system to monitor the Departure from Nucleate Boiling-Limiting Condition for Operation (DNS-LCO) rather than the excore detectors. Control Element Assembly (CEA) position and core average axial shape index are monitored to provide an alarm on power when the DNB-LCO is exceeded. Specifically, the BASSS determines allowable power level from knowledge of CEA posi-tion, total integrated radial peaking factor, and core average axial shape index using the on-line computer code PSINCA. The BASSS provides an alarm on power if the measured power level exceeds this allowable level.
PSINCA first calculates the core average axial shape index using the incore detector signals and signal-to-power coefficients from INCA (Ref. 1). The code then calculates the allowable power level of the core based on the core average axial shape index, the amount of inser-tion of the first regulating bank (CEA bank 5), and the total integrated radial peaking factor.
The allowable power level is calculated at two minute intervals.
An example of the system is presented in a sample calculation based on input data from the Calvert Cliffs Unit 1 Cycle 4 set point evaluation.
The results show an improved operating margin relative to the present.
excore DNB-LCO.
Several Technical Specification modifications are required in order to implement the BASSS on Calvert Cliffs Units 1 and 2.
These modifica-tions are also presented in the topical report.
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1 Summary of Review We have reviewed the material presented in the subject report with regard to the completeness with which it demonstrates that allowable power level can be ascertained and monitored by knowledge and use of CEA position, total integrated radial peaking factor, and core average axial shape index. We reviewed the analytical models employed, the uncertain-ties allowed for, the conservatism in the assumptions of the analysis, and the Technical Specification changes required for implementation of the BASSS for Calvert Cliffs Units 1 and 2.
In addition, we had our Technical Assistance consultants of Brookhaven National Laboratory perfonn an independent review of the material presented by CE.
A more detailed description of the derivation of the empirical relation-ships used by PSINCA to calculate the core average axial shape index has been supplied by CE in response to initial questions by the staff con-cerning BASSS (Ref. 2). We have reviewed this fonnulation which consists of fitting three Fourier functions to the equivalent power for adjacent levels of incore detectors to synthesize the power distribution in each half of the core and find it acceptable.
We have reviewed the algorithm used by PSINCA to calculate the allowable power level based on the core average ax41 shape index, the amount of insertion of the first regulating bank, and the associated total inte-grated radial peaking fa.ctor and find that it provides a conservative fit to the actual power limit and is, therefore, acceptable.
The measurement uncertainty on CEA position is applied directly to the input value of CEA position used in PSINCA whereas the other applicable uncertainties and biases are included in either the BASSS algorithm or the PSINCA computer code. These uncertainties are:
I temperature measurement, 2
flow measurement.
3 power measurement.
4 pressure measurement.
5) integrated radial peaking factor measurement, and 6) axial shape index measurement.
The values of these uncertainties are not provided as part of this report and, therefore, were not evaluated during this review. A con-current review effort is underway to provide an evaluation of these uncertainties in a separate topical report (Ref. 3).
We have reviewed the modificatic $ b the Technical Specifications for l
l Calvert Cliffs Units 1 and 2 %uiryt ih order to implement the BASSS and find these modificatiorf 1pr ale.
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Evaluaiica Procedure The review of topical report CEN-119(B)-P has been conducted within the guidelines provided by the Standard Review Plan (NUREG 75/087). Suf-ficient infomation has been presented in the repcrt and in responses to our questions to pemit the conclusion that the BASSS methodology is a suitable technique to infer the core average axial shape index in order to assess the operating margin of the Calvert Cliffs Units I and 2.
Regulatory Position Based on our review of the areas described above, we conclude that the subject report is an acceptable reference for the general methodology of-the BASSS to detemine core average axial shape index from incore detector readings and to provide an alam on power when the DNB-LCO is exceeded for the Calvert Cliffs Units 1 and 2.
The BASSS is valid for CEA insertions of CEA bank 5 from all rods out (ARO) to 55 percent inserted. Operation of the Calvert Cliffs units with insertions greater than 55 percent of bank 5 will require monitoring of the DNB-LCO with the excore DNB axial flux offset control limits. The values for the uncertainties used in the BASSS are intentionally excluded from this review and are presently under review in a separate effort (Ref. 3).
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References 1.
CENPD-145, " INCA-Method of Analyzing Incore De;. tor Data in Power Reactors," April 1975.
2.
Letter from A. E. Lundvall to R. A. Clark, Responses to NRC Questions on BASSS (CEN-119(B)-P), March 4, 1981.
3.
CEN-124(B)-P, " Statistical Combination of Lincertainties, Part 1, 2, and 3," March 1980.
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