ML20235S773

Application for Amend to License DPR-62,changing Reactor Water Level Setpoint for Isolation of Group 1 Primary Containment Isolation Valves from Low Level 2 to Low Level 3.Proprietary GE Topical Rept NEDC-30106-P Encl.Fee Paid

ML20235S773
Person / Time
Site:	Brunswick
Issue date:	09/29/1987
From:	Eury L CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML19304B551	List: ML20235S773 ML20235S790
References
NLS-87-173, NUDOCS 8710090133
Download: ML20235S773 (3)

Text

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CD&L Carolina Powet & Light Company .

SERIAL: NLS-87-173 SEP 2 91937 87TSB18 10CFR50.90 United States Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-324/ LICENSE NO. DPR-62 REQUEST FOR LICENSE AMENDMENT MSIV WATER LEVEL SETPOINT CHANGE  !

Gentlemen:

SUMMARY

l 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 i

Specifications (TS) for the Brunswick Steam Electric Plant (BSEP), Unit No. 2. The proposed changes to Section 3/4.3.2 change the reactor water level setpoint for the isolation of the Group i primary containment isolation valves from Low Level 2 to Low Level 3. The revisions also correct the existing master trip unit numbers to agree with-l current plant conventions.

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) DISCUSSION Lowering the main steam isolation valve (MSIV) setpoint from Low Level 2 (LL2) to Low Level 3 (LL3) is an NRC Staff recommendation to meet NUREG-0737, item II.K.3.16 requirements relating to safety / relief valve (S/RV) challenges. This change has also been '

recommended by the General Electric BWR Owners' Group and has been implemented at other BWRs to which it applies.

The following benefits will be realized as a result of the MSIV setpoint change:

1. Reduction in the probability of MSIV closure (reactor isolation). Reactor isolation leads to a loss of feedwater flow to the vessel, thereby making the feedwater system unavailable for level control, and the main condenser unavailable as a heat sink. Instead, high pressure coolant injection (HPCI) and  ;

reactor core isolation cooling (RCIC) would be required for level control, with the suppression pool serving as the heat sink. By reducing the probability of MSIV closure, use of HPCI and RCIC for level control and the suppression pool as a heat sink could be reduced.

2. Reduction in S/RV challenges. When the MSIVs close, the main condenser is not available as a heat sink and the pressure rises in the vessel causing the S/RVs to open and discharge steam to the suppression pool. Changing the setpoint (

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(thereby reducing the likelihood of MSIV closure) will reduce containment duty caused by steam discharge to the suppression pool. In addition, S/RV

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maintenance and the possibility of a S/RV becoming stuck open would also be reduced since S/RV challenges would be reduced.

3. Prevention of unnecessary use of the suppression pool as a heat sink. As stated above, the suppression pool is used as the heat sink for core decay heat in the event that the main condenser is unavailable. If the MSIVs close and an ATWS event takes place, there could be excessive suppression pool heatup. Lowering the MSIV setpoint would reduce the possibility of such an event, thereby limiting use of the suppression pool as a heat sink.

4. Possible increase in the life expectancy of the feedwater sparger. Use of HPCI, without the benefit of feedwater, may. result in cold water injection into the vessel, causing thermal cycles at the feedwater sparger. This could contribute- ]

i to feedwater sparger fatigue. Lowering the MSIV setpoint would reduce the >

1 possibility of HPCI use without feedwater and thereby reduce the probability of sparger fatigue. i The level setpoints for the main steam line drain valves (B21-F016 and B21-F019) and the ,

reactor water sample line valves (B32-F019 and B32-F020) are also being lowered from ]

LL2 to LL3. These valves, together with the MSIVs, are the current Group 1 primary .I containment isolation valves. Lowering the water level setpoint for these valves will  !

maintain the present Group 1 structure and functions, thereby eliminating possible operator confusion and training problems. .

I SIGNIFICANT HAZARDS 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: l

1. The proposed amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated. The setpoint change was evaluated with respect to several operating parameters, including the minimum critical power ratio (MCPR), peak vessel pressure, radiation I release, and shutdown capability during ab 1ormal operational transients. Fuel I cladding integrity during a loss of coolant accident (LOCA) and the reactor response during an ATWS event were at::o evaluated. Results of this evaluation are provided in the GE Topical Report NEDC-30106-P, " Safety Review of Water Level Setpoint Change for Brunswick Steam Electric Plant, Units 1 and 2." As stated in Sections 4.2.3 and 4.2.4 of that report, the change will not cause a reduction in MCPR, an increase in the peak pressure, an increase in radiation release, a cause for equipment damage, a reduction in plant shutdown capability, or a decrease in core cooling capability. The MSIV level setpoint change has no impact on LOCA events previously evaluated, nor does it cause any safety concerns during an ATWS event. Thus, the probability or consequences of accidents previously evaluated will not be increased.

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l Document Control Desk NLS-37-173 / Page 3-i

2. The proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated. The LL3 Group 1 automatic trip circuitry will meet the current single active failure criteria and separation criteria. Thus, the possibility for malfunction of equipment important to safety is not created, nor are any new accidents or transients, different than those previously evaluated, created. j

3. The proposed amendment does not involve a significant reduction in the margin of safety. The LL3 reactor water level setpoint for the Group 1 PCIS valves still" ensures the effectiveness of the instrumentation used to mitigate the consequences of accidents" as justified by Sections 4 and 5 of NEDC-30601-P.

Therefore, the margin of safety is not reduced. l l

Based on the above reasoning, CP&L has determined that the proposed changes involve j no significant hazards consideration.

ADMINISTRATIVE INFORMATION The revised BSEP TS pages are provided in Enclosure 1. 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) 836-6242. l; Yours very truly, ff tf/26 L.W.E Senior Vice resident Operations Support LWE/ mss (5262 BAT)

Enclosure cc: Dr. J. Nelson Grace Mr. W. H. Ruland Mr. E. Sylvester Mr. Dayne H. Brown L. W. Eury, having been first duly sworn, did depose and say that the information contained herein is true and correct to the best of his information, knowledge and belief; and the sources of his information are officers, employees, contractors, and agents of Carolina Power & Light Company..

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