ML20236K638
| ML20236K638 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 08/03/1987 |
| From: | Cutter A CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20236K639 | List: |
| References | |
| 86TSB22, NLS-87-010, NLS-87-10, NUDOCS 8708070203 | |
| Download: ML20236K638 (3) | |
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Carolina Power & Light Company AU8-31987 SERIAL: NLS-87-010 86TSB22 10CFR 50.90 United States Nuclear Regulatory Commission Attention: Dccument Control Desk Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS.1 AND 2 DOCKET NOS. 50-325 & 50-324/ LICENSE NOS. DPR-71 & DPR-62 REQUEST FOR LICENSE AMENDMENT CONTROL ROD BANKED POSITION WITHDRAWAL Gentlemen:
SUMMARY
In accordance with the Code of Federal Regulations, Title 10, Parts 50.90 and 2.101, Carolina Power & Light Company (CP&L) hereby requests a revision to the Technical Specifications (TS) for the Brunswick Steam Electric Plant (BSEP), Unit Nos. I and 2.
The proposed changes to TS 3/4.1.4 and its bases require the use of the Banked Position Withdrawal Sequence (BPWS) as the Rod Worth Minimizer (RWM) Control Rod Program.
DISCUSSION General Electric (CE) has developed BPWS rod patterns applicable to Gi oup Notch Rod Sequence Control reactors, such as the BSEP units. The NRC issued a S ifety Evaluation Report (SER) to GE on October, 11,1985, which allows group notch reactors to take credit for the Control Rod Drop Accident (CRDA) statistical analysis and conclusions previously approved by the NRC for GE in an SER dated October 13,1983 for reactors using BPWS, enforced only by the RWM.
A BWR's control rods are removed from the reactor core from the bottom, thus the possibility that a control rod could become unlatched from its drive mechanism and later fall from the core, resulting in possible fuel failure, must be addressed. One of the mechanisms designed to ensure that fuel failure does not result if a CRDA should occur is the RWM. The RWM tracks control rod movement and generates rod blocks in the high worth area from 100-percent control rod de..alty (all control rods inserted) to appro.ximately 20-percent power. It ensures that a programmed control rod sequence is bei:rg followed when the < eactor is in the high worth area. The BPWS rod patterns have been analytically determined to keep the fuel pellet enthalpy less than 280 calories per gram under worst-case CRDA conditions.
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Document Control Desk NLS-87-010 / Page 2 Currently, Surveillance Requirement 4.1.4.1.2 requires verification that the control rod sequence input to the RWM computer is correct following its loading into the computer.
The proposed revision specifies that this seque%e program be GE's generic BPWS rod pattern program. Brunswick normally implements this program but does not take credit for its use in cycle specific reload topical reports. Specifying the use of BPWS rod patterns allow use of GE's generic CRDA analysis and eliminates the need for performing cycle specific analyses.
SIGNIFICANT liAZARDS ANALYSIS The Commission has provided standards in 10CFR50.92(c) for determining whether a significant hazards consideration exists. A proposed amendment to an operating license for a facility involves no significant hazards consideration if operation of the facility in accordance with the proposed amendment would not: (1) involve a significant increase in the probability or consequences of an accident previously evaluated, (2) create the possibility of a new or different kind of accident from any accident previously evaluated, or (3) involve a significant reduction in a margin of safety. Carolina Power & Light Company has reviewed this request and determined that:
1.
The proposed amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated. A generic, statistical analysis of the Control Rod Drop Analysis (CRDA) has been done by GE for the Banked Position Withdrawal Sequence (BPWS). This analysis verified that the resulting fuel enthalpies in the event of a CRDA would be less than 280 calories per gram as required by the fuel rod enthalpy limits specified in FSAR Section 15.4.6.1. A Safety Evaluation Report was issued by the NRC on October 13,1983, which approved the analysis. The proposed TS changes will enforce the use of BPWS rod patterns in the Rod Worth Minimizer (RWM). Adherence to the BPWS assures that a CRDA will not result in fuel failure.
2.
The proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated. The RWM and the Rod Sequence Control System (RSCS) are designed to protect against reactivity insertions which would result in fuel enthalples greater than 280 calories per gram. The BPWS method of rod withdrawal has been analyzed and determined to be a more ef fective and conservative method of minimizing rod worth during withdrawal of the first 50% of the control rods.
Therefore, no increase in the possibility of an excessive reactivity insertion accident is introduced.
3.
The proposed amendment does not involve a significant reduction in the margin of safety. The area of main concern for the CRDA is the high rod worth area from 100 percent control rod density to approximately 20 percent power. Enforcement of the BPWS by the RWM will prevent inadvertent movement of control rods in these vulnerable areas where a CRDA could cause major fuel damage. A similar unit and cycle specific control rod sequence program is currently in use at BSEP. Incorporation of the BPWS requirement into the TS will mandate its use thereby maintaining the margin of sarety. The NRC has approved this methodology in its SER of October 11,1985 and concluded that it is preferable for Group Notch Rod Sequence Control System plants to have the improved pattern control of the BPWS.
Document Control Desk NLS-87-010 / Page 3 -
Based on the above reasoning, CP&L has determined that the proposed changes involve no significant hazards consideration.
ADMINISTRATIVE INFORMATION The revised BSEP TS pages are provided in Enclosures 1 and 2. The Company has evaluated this request in accordance with the provisions of 10CFR170.12 and determined that a license. amendment application fee is required. A check for $150 is enclosed in payment of this fee.
Please refer any questions regarding this submittal to Mr. Sherwood R. Zimmerman at (919) 836-62t 2.
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A. B. Cutter - Vice President Nuclear Engineering ABC/ BAT /ppo (5091 BAT) 1 Enclosures cc:*
Mr. W. H. Ruland Dr. 3. Nelson Grace l
Mr. E. Sylvester Mr. D. H. Brown
- All with Enclosures 1 and 2 t
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A. B. Cutter, having been first duly sworn, did depose and say that the information l
contained herein is true and correct to the best of his information, knowledge and belief;-
l and the sources of his information are officers, employees, contractors, and agents of i
Carolina Power & Light Company.
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