ML20078P220
| ML20078P220 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 02/14/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20078P213 | List: |
| References | |
| NUDOCS 9502160331 | |
| Download: ML20078P220 (4) | |
Text
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j NUCLEAR REGULATORY COMMISSION WA8HINGTON. D.C. 2066 Moot 49.....
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION R_fLATED TO AMENDMENT N0.189 TO FACILITY OPERATING LICENSE NO. DPR-68 8
TENNESSEE VALLEY AUTHORITY E0WNS FERRY NUCLEAR PLANT. UNIT 3 DOCKET NO. 50-296
1.0 INTRODUCTION
On March 29, 1994, the Tennessee Valley Authority (the licensee) requested revision of the Technical Specifications (TS) for the Browns Ferry Nuclear Plant (BFN) Unit 3.
The proposed changes reflect a design change adding a load shedding logic system to the BFN Unit 3 480-volt emergency power supplies.
The proposed TS changes include the addition of a Limiting Condition for Operation (LCO) 3.9. A.5.b and a Surveillance Requirement (SR) 4.9.A.3.b for the 480-volt load shedding logic system. The addition of the load shedding logic system is to ensure that the maximum capacity of the 1
emergency diesel generators (ED3s) at BFN Unit 3 would not be exceeded during a postulated loss of offsite powar (LOOP) concurrent with a loss-of-coolant accident (LOCA).
2.0 EVALUATION As part of the design baseline verification program to support restart of BFN Unit 3, the licensee performed an EDG capacity analysis.
This analysis showed that the maximum capacity of Unit 3 EDGs 3A and 3C could be exceeded and overloaded during multiunit operation if a LOOP occurred concurrently with a LOCA.
Therefore, before BFN Unit 3 is restarted, the licensee will implement a design change to automatically shed 480-volt loads not required for short-term post-accident mitigation from the auxiliary power system.
The NRC staff has reviewed the proposed changes in TS Section 3.9/4.9,
" Auxiliary Electrical System" associated with the addition of LC0 3.9.A.5.b and SR 4.9.A.3.b.
The staff's evaluation of each proposed TS amendment for BFN Unit 3 is as follows:
J Logic Systems Limiting Condition for Operation The licensee proposes that current LC0 3.9.A.5 be renamed " Logic Systems," and that its current content be redesignated as LC0 3.9.A.5.a.
In addition, the licensee proposes to add LCO 3.9.A.5.b, which states that the 480-volt load shedding logic system is operable.
ENCLOSURE 2 y
9502160331 950214 PDR ADOCK 05000296 P
. BFN Unit 3 has four EDGs that supply standby power to the Unit 3 auxiliary power system, which consists of:
four 4-kV shutdown boards, two 480-volt shutdown boards, five reactor motor operated valve (RMOV) boards, four motor generator sets, two diesel auxiliary boards, and a standby gas treatment system board.
Currently, the 480-volt auxiliary power system at BFN Unit 3 has provision for undervoltage load shedding only.
With the EDG capacity analysis showing that the maximum capacity of the Unit 3 EDGs 3A and 3C could be exceeded and overload these EDGs during multiunit operation if a LOOP occurs concurrently with a 1.0CA, the licensee plans to install a 480-volt load shedding logic system.
With a LOOP concurrent with a LOCA signal, the system will trip 480-volt loads that are not required for short-term post-accident mitigation from 480-volt shutdown boards, diesel auxiliary boards, and RMOV boards.
This will ensure that the loads on the EDG are within the rated capacity.
To provide appropriate controls on the load shed system availability, the licensee has proposed to revise TS LC0 3.9.A.S.b.
Since the purpose of the auxiliary power system is tc ensure an adequate supply of electrical power for operation of those systems required for safe shutdown of BFN Unit 3, the staff finds that implementation of a design change whereby nonessential loads are shed from the Unit 3 auxiliary power system ensures that the EDGs can supply adequate power under postulated design basis accident (i.e., LOOP and LOCA) conditions.
The licensee also states that BFN Units 1 and 2 share four EDGs, and that there har always been a 480-volt load shedding logic feature for these units from the time the units were licensed.
The staff has reviewed the current TS for BFN Units 1 and 2, and has confirmed that a load shedding provision similar to that proposed for BFN Unit 3 exists.
The staff finds that proposed LC0 change fcr BFN Unit 3 makes its TS consistent with those of Units I and 2 in this regard.
In addition, the staff has audited the licensee's design change documentation prepared in accordance with 10 CFR 50.59, and finds that it provides adequate basis for implementing the load shedding logic system and assurance that this objective is met.
The staff concurs with the licensee that addition of this system is necessvy and should be addressed in the TS.
On this basis, the staff concludes the proposed LC0 3.9.A.S.b is acceptable.
Load Shed Surveillance Requirements To ensure that the 480-volt load shedding logic system is tested regularly, the licensee proposes to add TS SR 4.9.A.3.b, which states:
Once every 18 months, the condition under which the 480-volt load shedding logic system is required shall be simulateri to demonstrate that the load shedding logic system world initiate load shedding signals on the diesel auxiliary boaros, RMOV boards, and the 480-volt shutdown boards.
The licensee explains that on the basis of its review of NUREG-1433, " Standard Technical Specification (STS), General Electric Plants, BWR/4," and Paragraph 2.a of Regulatory Gui.ie (RG) 1.108, " Periodic Testing of Diesel Generator Units Used as Onsite ilectrical Power Systems at Nuclear Power Plants," the 480-vcit load shedding logic system should be tested every 1
i
)
)
. 18 months.
By testing the system every 18 months, the licensee contends that the capability of the EDGs to supply power during a design basis accident is ensured, thus ensuring minimum performance standards are preserved.
The staff has reviewed SR 3.8.1.19 of NUREG-1433 and Paragraph 2.a of RG 1.108 and finds that the proposed interval is consistent with existing regulatory guidance.
Therefore, the addition of SR 4.9. A.3.b is acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Alabama State official was notified of the proposed issuance of the amendment.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change requirements with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes the surveillance requirements.
The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (59 FR 39597).
Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
5.0 CONCLUSION
The Commission has concluded, based upon the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and (3) issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
Peter Kang Dated: February 14, 1995
Mr. Oliver D. Kingsley, Jr.
BROWNS FERRY NUCLEAR PLANT Tennessee Valley Authority cc:
Mr. O. J. Zeringue, Sr. Vice President Mr. Pedro Salas Nuclear Operations Site Licensing Manager Tennessee Valley Authority Browns Ferry Nuclear Plant 3B Lookout Place Tennessee Valley Authority 1101 Market Street P.O. Box 2000 Chattanooga, TN 37402-2801 Decatur, AL 35602 Dr. Mark 0. Medford, Vice President TVA Representative Engineering & Technical Services Tennessee Valley Authority l
Tennessee Valley Authority 11921 Rockville Pike, Suite 402 3B Lookout Place Rockville, MD 20852 1101 Market Street Chattanooga, TN 37402-2801 Regional Administrator U.S. Nuclear Regulatory Commission Mr. D. E. Nunn, Vice President Region II New Plant Completion 101 Marietta Street, NW., Suite 2900 Tennessee Valley Authority Atlanta, GA 30323 3B Lookout Place 1101 Market Street Mr.. Leonard D. Wert Chattanooga, TN 37402-2801 Senior Resident Inspector I
Browns Ferry Nuclear Plant Mr. R. D. Machon, Site Vice President U.S. Nuclear Regulatory Commission Browns Ferry Nuclear Plant 10833 Shaw Road Tennessee Valley Authority Athens, AL 35611 P.O. Box 2000 Decatur, AL 35602 Chairman Limestone County Commission General Counsel 310 West Washington Street Tennessee Valley Authority Athens, AL 35611 ET llH 400 West Summit Hill Drive State Health Officer Knoxville, TN 37902 Alabama Department of Public Health 434 Monroe Street Mr. P. P. Carier, Manager Montgomery, AL 36130-1701 Corporate Licensing Tennessee Valley Authority 4G Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801 Mr. T. D. Shriver Nuclear Assurance and Licensing Browns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35602 i
.,.