ML20217N371

Safety Evaluation Supporting Amends 111,111,104 & 104 to Licenses NPF-37,NPF-66,NPF-72 & NPF-77,respectively

ML20217N371
Person / Time
Site:	Byron, Braidwood
Issue date:	10/13/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20217N369	List: ML20217N363 ML20217N371
References
NUDOCS 9910280199
Download: ML20217N371 (6)

Text

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.111 TO FACILITY OPERATING LICENSE NO. NPF-37. AMENDMENT NO.111 TO FAC'LITY OPERATING LICEN6E NO. NPF-66, l - AMENDMENT NO.' 104' TO FACILITY OPERATING LICENSE NO. NPF-72. AND AMENDMENT NO.104 TO FACILITY OPERATING LICENSE NO. NPF-77 COMMONWEALTH EDISON COMPANY BYRON STATION. UNIT NOS.1 AND 2 i );- BRAIDWOOD STATION. UNIT NOS.1 ANQ2 ] . DOCKET NOS. STN 50-454. STN 50-455. STN 50-456 AND STN 50-457 1.0 ' INTRODUCTION . By letter. dated June 30,1949, Commonwealth Edison Company (Comed, the licensee) requestad an amendment to Operating License Nos. NPF-37 and NPF-66 for_ Byron Station, i

Units 1 and 2, and Operating License Nos. NPF-72 and NPF-77 for Braidwood Station, Units 1 I

- and 2. The amendments correct an oversight that occurred in Technical Specification (TS) 3.8.5, *DC Sources - Shutdown," during the implementation of the Improved Standard -Technical Specification (iSTS). Also included in the request are administrative changes to Braidwood's TSs to delete a number of references to AT&T batteries since all AT&T batteries have been replaced with batteries manufactured by Charter Power Systems, Inc. (C&D). The request also requested removal of the one-time Allowed Outage Time (AOT) extension approved for Braidwood in Amendment Nos. 99 and 99, because the activities addressed by those amendments (replacement of AT&T batteries) are complete. X . 2.0, ' BACKGROUND During the implementation of the iSTS, an oversight occurred in Limiting Condition for LOperation (LCO) 3.8.5 "DC Sources -- Shutdown.* The present LCO 3.8.5 requires two sources of DC power when required by LCO 3.8.10, " Distribution Systems - Shutdown"; i however, neither source is permitted to be powered via the DC cross-tie breakers to the j fopposite unit.L The requested _ change will permit the use of the DC cross-tie breakers to supply ' power from the operating unit to one DC bus of the other unit when in Mode 5, Mode 6, or i during the movement of irradiated fuel assemblies. 9910290199 991013 I j 7" " SE i _ c-

I The request also resolves an inconsistency between LCO 3.8.5 and LCO 3.8.4, Conhtion C. Condition C addresses "one DC electrical power division cross-tied to opposite unit DC electrical power subsystem with an inoperable source, while the opposite unit is in Mt.de 5, 6, or is'defueled."; This provision is included explicitly to accommodate maintenance andOr testing o < the' shutdown' unit's DC subsystems. ' Comed replaced all'AT&T r und cell batte.ies at Braidwood with C&D batteries Administrative changes are included in the request to delete various references to AT&T batteries in LCO 3.8.4, *DC Sources - Operating;" LCO 3.8.5, "DC Sources - Shutdown;" LCO 3.8.6, " Battery q Cell Parameters;" and LCO 3.8.9, " Distribution Systems - Operating." Also included in the request is the removal of the AOT approved in TS Amendment Nos. 99 and 99 for Braidwood. j i 3.0 EVALUATION 3.1 QQ_Qross-Tie Breakers Between Units ' The proposed TS change will allow one required source of DC for a unit in Mode 5,6, or durin ~ the movement of irradiated fuel assemblies to be provided by the DC bus cross-tie from the Lopposite unit, or by the associated battery aM either the associated charger or a temporary j 1 charger, or the associated charger alone. This change removes the requirement from LCO 3.8.5, item b, to have at least one cross-tie breaker open. This cross-tie breaker requirement will now apply only to LCO 3.8.5, item a. 1 The present TS 3.8.5, "DC Sources - Shutdown," of Byron and Braidwood, reads as fo!bwe: 3.8.5' DC Sources - Shutdown . LCO 3.8.5 The following shall be OPERABLE with at least one unit cross-tie breaker per division open: . a.- One DC electrical power subsystem capable of supplying one division of the = onsite Class 1E DC electrical power distribution subsystem (s) required by LCO 3.8.10, " Distribution System - Shutdown"{ and b.' One source of DC electrical power, other than that required by LCO 3.8.5.a, capable ' of supplying the remaining onsite Class 1E i DC electrical power distrit.ution c subsystem (s) when required by LCO 3.8.10. I The requested changes will read as follows: LCO 3.8.5~ L The forosving shall be OPERABLE: v U

g ii. 1 One DC electrical power subsystem a. capable of supplying one civision of the onsite Class 1E DC electrical power- - distribution subsystem (s) required by LCO - 3.8.10, " Distribution System - Shutdown," with at least one unit cross-tie breaker open: and b.

One source _of DC electrical power, other than that required by LCO 3.8.5.a. capable

of supplying the remaining onsite Class 1E DC electrical power distribution subsystem (s) when required by LCO 3.8.10. { The applicability, actions' and surveillance requirements will not change. The licensee analyzed the impact of the change on the plant operation and summarized four i cases: - 3.1.1' Case 1: One unit shutdown in Mode 5,6, or moving irradiat.ed fuel assemblies, and the other unit is operating in Mode 1,2,3, or 4; and one of the shutdown unit's DC source becomes inoperable (maintenance or failure of the battery cr the charger). When the inoperable source is cross-tied to the opposite bus, the operating unit will be in LCO 3.8.4, condition C, and associated required action must be performed. Required action C.1 requires that the DC bus load of the opposite unit is verified to be equal or less than ' 200 amps once per 12 hours when the opposite unit has an inoperable battery. Required action C.2 is to "open at least one cross-tie breaker between the cross-tied divisions with a completion time of 7 days," and ensures that measures are being taken to restore the inoperable htttery or battery charger. If the DC bus on the' shutdown unit that is cross-tied is the bus credited in LCO 3.8.5, item a, the shutdown unit will be in LCO 3.8.5, Condition A, and the required actions must be performed. Action A.1 specifies that the shutdown unit either immediately declare the affected . required feature (s) inoperable or immediately follow required actions A.2.1 - A.2.5 to suspend core alteration, suspend movement of irradiated fuel assemblies, initiate action to suspend positive reactivity additions, initiate action to restore required DC electrical power subsystems to . operable status, and declare affected Low Temperature Overpressure Protection feature (s) . Inoperable. These actions minimize.the probability of the occurrence of postulated events and - ensure that actions are immediately taken to restore the DC power. , 3.1.E Case 2 Both units are shutdown and a shutdown unit's DC source (battery or charger) becomes incperable (maintenance or failure). When the ' bus with an inoperable source is cross-tied to the opposit6 unit, the requested TS ichange to LCO 3.8.5 will permit the continuation of evolutions of the shutdown unit with the - inoperable source, as long as the cross-tied bus on the unit with the inoperable source is the 't i i )

m j -t. 1 -41 bus credited for LCO 3.8.5, item b. The other shutdown unit will be in LCO 3.8.5, Condition B, 2 with Required Action B.1 to verify the opposite unit's DC bus load is less than or equal to 200 amps once per 12 hours. Action B.1 is modified by a note stating that "only required when opposite unit has an inoperable battery ".The load limit of 200 amps ensures that the unit ' specific DC subsystem will not be overloaded in the event of a concurrent event on both units. ) . LCO 3.8.5, Required' Action B.2, requires the associated cross-tie breaker to'be opened within 17 days so measures.are taken t.o restore the inoperable battery charger to operable, and '} reestablish independence of the DC subsystems. These provisions exist in the present TS and. { existed in the TS prior to the conversion to the iSTS. i 3.1.3 Case 3: One unit is shutdown in Mode 5, 6, or moving irradiated fuel assembly. The j other unit is operating in Mode 1, 2, 3, or 4, and one of the operating unit battery { chargers becomes inoperable _(maintenance or failure). j ' In this case, the operating unit is in LCO 3.8.4, Condition A. ' Req $ ired Action A.1 allows the use - { of the cross-tie to the opposite unit within two hours to restore the electrical power to the affected divisionf Action A.2 requires the battery charger to be restored to OPERABLE within 24 hews: The two-hour time is adequate to evaluate the cause of the battery charger failure, to deterNne if the DC bus of the opposite unit is available for support, and to perform the cross-tie procecare. The 24 hours to limit the cross-tied condition is a reasonable time for repairs. 3.1.4L Case 4: Use of temporary battery charger in conjunction'with the associateil battery on a shutdown unit. t If the DC bus on the ' hutdown unit credited in LCO 3.8.5, item b, is using a temporary charger, s then shutdown unit evolutions may continue without restriction. If the DC bus on the shutdown 'l unit credited in LCO 3.8.5, item a, is using a temporary charger, then the shutdown unit will be in LCO 3.8.5, Condition A, as described above. ~ The staff agrees with the licensee's analysis of these four cases and finds that it demonstrates the. acceptability of the proposed changes for various operational modes. in addition, the Byron and Braidwood Updated Final Safety Analysis Report, Section 8.3.2.1.1,' states that the i interconnection between each unit's Class 1E 125V DC systems via the cross-tie is limited by procedural and administrative controls,. The criteria specifying the allowable combinations of ) maintenance and test operations are govemed by the plant TS. i The cross-tie between the 125V DC ESF buses are each provided with two normally locked open, manually operated circuit breakers. No interlocks are provided since the interconnected buses are not redundant. The cross-tie load is limited to 200 amps and the breakers are i coordinated with the DC bus main breakers io' assure that due to a f:: ult the cross-tie will be i isolated., The cross-tie breaker " closed" is alarmed to alert the ope ator when the units are cross-tied.~ ~ The TSs in effect prior to the implernentation of the ISTS, LCO 3/4.8.2.1, "DC Sources - ! Operating / and LCO 3/4.8.2.2, "DC Sources - Shutdown," allowed operation as proposed by i this change. Previously, LCO 3/4,8.2.2, required only one DC bus on a shutdown unit to be

i 4 , operable with the associated DC bus cross-ties opan. The operation with a DC cross tie closed ~ is within the desigr, bases of Byron and Braidwood Stations and maintains the ability to mitigate I 4 the consequeaces of any accident or transient. The limitation not to use the cross-tie during Shutdown condttions was an overeght during the conversino to the ISTS, Based on the design and proposed operation of the cross-tie feature, the staff concludes that th~is change is acceptable. 3.2 ' Referencetto AT&T Round Cell Batteries At Braidwocd, Comed bad installed AT&T round cell high-specific gravity-type batteries, which exhibited loss of capacity when dischaged nd recharged. The licensee replaced the AT&T batteries with C&D batteries, and req. Jested that all references to AT&T batteries in TS Section l 3.8, " Electrical Power Systems," be deleted. This is considered an administrative change and is acceptable. 3.3 Allowed Outaae Time Extension By license Amendment Nos. 99 and 99, the licensee was allowed a 10-day completion time for replacement of the AT&T batteries at Braidwood Unit 2. This activity is complete and, therefore, the deietion of required action C.2 in LCO 3.8.9, " Distribution Systems - Operating," is acceptable. ( 3.4 Other Administrative Chances The following TS administrative changes are also included in the licensee's request: !n LCO 3.8.4, " Required Action C.1," and in LCO 3.8.5, " Required Action B.1," the a. l change deletes "s100 amps for AT&T (s200 amps for C&D)" and is replaced by "s200 amps." i b. In LCO 3.8.4, Condition D is deleted, Condition E is renumbered to Condition D. and - Condition F is renumbered to Condition E. Whenever Conditions are renumbared, the associated Required Actions are also renumbered. In Surveillance Requirements 3.8A1,3.8.4.7, and 3.8.4.8, and Table 3.8.6-1, " Battery c. Cell Parameters Requirements," rett.rences to AT&T and C&D are deleted. The staff agrees that these changes are appropriaM since AT&T batteries are no longer installed at Braidwood, and the changes, therefore, are acceptable. 4.0

SUMMARY

The staff has reviewed the licensee's requests for TS changes to the requirements related to the cross-tie of DC buses, and severa! administrative changes. The proposed changes are acceptable. J

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l v h m,j L 5.01 STATE CONSULTATION j I I I '#<g ,,,6 in accordance with the Commission's regulations, tne lilinois State official wa's notified of the . proposed issuance of the amendme,ntu Ths State official had no comments. y .x \\.

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2 NI. k' / 6.0K f,NVIRONMENTAL CONSJpERATION ' w' 9 [, 9The amsndments change a requirsment with respect'to the installation'or use of a facility. ~ J

component located within thelestricted aree as defined in 10 CFR Part 20. The NRC staff has o L determined that the amendments involve no significant increase in the amounts, and no -

Lsignificant 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 invoNe no significant hazards consideration, and there has been no public comment on such finding ! (64 FR 43767).LAccordingly, the amendments meet the eligibility enteria for categorical y;.

exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environn' ental f impact statement or environmental assessment need be prepared in connection with the u

~. issuance of the amendments. ~ 7.0 - ' CONCLUSION 1 m 4 ~. JThe Commission has coricluded, based on the considerations discussed above, that: (1) there

• 7 lis reasonable assurance that the health and safety of the public will not be endangered by

{ . operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments'will not be inimical to the - common defense and security o'r to the health and safety of the public. -{ m f Vincipal Contributor: LS.Sabk ] ~ a 3 _ _ _ ' + t Datef L0ctober 13,'(1999) h', y { 1 c 1 l 4 t t i I -I -) ,b m. H T ( ^' W i e A;. '3; . c] '}}