ML25353A596

Application to Revise Technical Specifications to Adopt TSTF-601, Extend Shield Building Completion Time After Refueling

ML25353A596
Person / Time
Site:	Millstone
Issue date:	12/18/2025
From:	James Holloway Dominion Energy Nuclear Connecticut
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
25-301
Download: ML25353A596 (0)

Text

Dominion Energy Nuclear Connecticut, Inc 5000 Dominion Boulevard, Glen Allen, VA 23060 DominionEnergy.com December, 18, 2025 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNITS 3 if;; Dominion

iiiii" Energy Serial No.

NRA/NDM:

Docket No.:

License No.:

25-301 RO 50-423 NPF-49 APPLICATION TO REVISE TECHNICAL SPECIFICATIONS TO ADOPT TSTF-601, "EXTEND SHIELD BUILDING COMPLETION TIME AFTER REFUELING" Pursuant to 10 CFR 50.90, Dominion Energy Nuclear Connecticut, Inc. (DENC) is submitting a request for an amendment to the Technical Specifications (TS) for Millstone Power Station Unit 3 (MPS3).

DENC requests adoption of Technical Specifications Task Force (TSTF) Traveler 601, "Extend Shield Building Completion Time After Refueling," which is an approved change to the Standard Technical Specifications (STS), into the MPS3 TS. TSTF-601 revises the shield building TS to add a new Action that is applicable prior to criticality following a refueling outage. of this letter provides a description and assessment of the proposed change. Attachment 2 provides marked-up MPS3 TS pages showing the proposed changes. Attachment 3 provides marked-up MPS3 TS Bases pages showing the proposed changes. The TS Bases mark-ups are provided for information only.

DENC requests that the amendment be reviewed under the Consolidated Line Item Improvement Process (CLIIP).

Approval of the proposed amendment is requested within 6 months of completion of the NRC's acceptance review, to support the MPS3 Fall 2026 Refueling Outage. Once approved, the amendment shall be implemented within 90 days.

This letter contains no new regulatory commitments.

In accordance with 10 CFR 50.91(b), a copy of this amendment request is being provided to the State of Connecticut.

Serial No.: 25-301 Docket No.: 50-423 Page 2 of 3 If you have any questions or require additional information, please contact Nick Maynard at (804) 273-3910.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on December, 18, 2025 Sincerely, James E. Holloway Vice President - Nuclear Engineering and Fleet Support Attachments:

1. Evaluation of the Proposed Change

2. Marked-up Technical Specification Pages for MPS3

3. Marked-up Technical Specification Bases Pages for MPS3 (For Information Only)

cc:

U.S. Nuclear Regulatory Commission Region I 475 Allendale Road, Suite 102 King of Prussia, PA 19406-1415 Theo L. Edwards Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop O-8C04 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station Director, Radiation Division Department of Energy and Environmental Protection 79 Elm Street Hartford, CT 06106-5127 Serial No.: 25-301 Docket No.: 50-423 Page 3 of 3 EVALUATION OF THE PROPOSED CHANGE Dominion Energy Nuclear Connecticut, Inc.

Millstone Power Station 3 Serial No.: 25-301 Docket No.: 50-423

1.0 DESCRIPTION

Serial No.: 25-301 Docket No.: 50-423, Page 1 of 4 Dominion Energy Nuclear Connecticut, Inc. (DENC) requests adoption of Technical Specifications Task Force (TSTF) Traveler 601, "Extend Shield Building Completion Time After Refueling," which is an approved change to the Standard Technical Specifications (STS), into the Millstone Power Station Unit 3 (MPS3) Technical Specifications (TS).

TSTF-601 revises the shield building TS to add a new Action that is applicable prior to criticality, following a refueling outage.

2.0 ASSESSMENT

2.1 Applicability of Safety Evaluation DENC has reviewed the safety evaluation for TSTF-601 provided to the Technical Specifications Task Force in a letter dated March 6, 2025. This review included the NRC staff's evaluation, as well as the information provided in TSTF-601. DENC has concluded that the justifications presented in TSTF-601, and the safety evaluation prepared by the NRC staff are applicable to MPS3 and justify this amendment for the incorporation of the changes to the MPS3 TS.

TSTF-601 and the NRC's safety evaluation discuss the application of STS Limiting Condition for Operation (LCO) 3.0.4.b when using the new Action. While not based on the STS, the MPS3 TS contain a similar allowance and the discussion is applicable.

2.2 Variations DENC is proposing the following variations from the TS changes described in TSTF-601 or the applicable parts of the NRC staff's safety evaluation.

MPS3 Variations The MPS3 TS 3.6.6.2, "Secondary Containment," is equivalent to the STS 3.6.8, "Shield Building." The Secondary Containment serves the same purpose as the Shield Building described in the STS.

The MPS3 TS are not based on the STS and the MPS3 TS Actions are not formatted in the "Condition / Required Action I Completion Time" style used in the STS. To accommodate this difference, the TSTF-601 changes to the TS Actions are formatted to be consistent with the MPS3 TS without changing the intent.

The MPS3 TS Actions use Mode labels, provided in MPS3 TS Table 1.2, instead of the Mode numbers used in the STS. However, the Modes and Mode labels correspond to the STS Modes.

These differences do not affect the applicability of TSTF-601 to the MPS3 TS.

3.0 REGULATORY ANALYSIS

3.1 No Significant Hazards Consideration Serial No.: 25-301 Docket No.: 50-423, Page 2 of 4 Dominion Energy Nuclear Connecticut, Inc. (DENC) requests adoption of TSTF-601, "Extend Shield Building Completion Time After Refueling," which is an approved change to the Standard Technical Specifications (STS), into the Millstone Power Station Unit 3 (MPS3) Technical Specifications (TS). TSTF-601 revises the MPS3 secondary containment TS to add a new Action that is applicable prior to criticality following a refueling outage.

1.

Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No The proposed change provides a longer time for the enclosure building or secondary containment to be inoperable in Hot Standby and Hot Shutdown following the refueling of the reactor and prior to reactor criticality. The enclosure building and secondary containment are not initiators of any accident previously evaluated. As a result, the probability of an accident during the extended time is not significantly increased. The consequences of a previously analyzed accident during the extended time are no different than the consequences of the accident during the existing time. Further, the limitations on the use of the extended time ensure that the consequences are reduced from those that would occur when at power. Hence, the consequences are not significantly increased.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2.

Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No The proposed change provides a longer time for the enclosure building or secondary containment to be inoperable in Hot Standby and Hot Shutdown following the refueling of the reactor and prior to reactor criticality. No new or different accidents result from utilizing the proposed change. The change does not involve a physical alteration of the plant (i.e., no new or different type of equipment will be installed). Permitting the enclosure building and secondary containment to be restored in Hot Standby and Hot Shutdown instead of Cold Shutdown does not create a significant change in the methods governing normal

Serial No.: 25-301 Docket No.: 50-423, Page 3 of 4 plant operation. In addition, the changes only affect a TS Action and therefore do not alter the assumptions made in the safety analysis.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

3.

Does the proposed amendment involve a significant reduction in a margin of safety?

Response: No The proposed change provides a longer time for the enclosure building or secondary containment to be inoperable in Hot Standby and Hot Shutdown following the refueling of the reactor and prior to reactor criticality. The proposed change does not adversely affect existing plant safety margins or significantly affect the reliability of the equipment assumed to operate in the safety analysis.

As such, there are no changes being made to safety analysis assumptions, safety limits or limiting safety system settings that would adversely affect plant safety as a result of the proposed change.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above, DENC concludes that the proposed change presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of "no significant hazards consideration" is justified.

3.2 Conclusion In conclusion, based on the considerations discussed above, (1) there is 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 amendment will not be inimical to the common defense and security or to the health and safety of the public.

4.0 ENVIRONMENTAL CONSIDERATION

A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement.

However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or a significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.

Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Serial No.: 25-301 Docket No.: 50-423, Page 4 of 4 Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

Serial No.: 25-301 Docket No.: 50-423 MARKED-UP TECHNICAL SPECIFICATIONS PAGES FOR MPS3 Dominion Energy Nuclear Connecticut, Inc.

Millstone Power Station Unit 3

CONTAINMENTS. STEMS FOR OPERATIOJ S&:ond:i Containment shall be OPERABLE.

AP:PU ABJLITY!

MODE l _ J_ a:nd 4.

ACTTO :

Un:113 TS Insert Serial No.: 25-301 Docket No.: 50-423 Page 1 of 2

~wtti:rS:ecm1tta1ry OJ11iitaim1rem inopaiab're, 1&mre 3ecouda,1 O:.iu,caimnem m OP~

• withi.fl 24 hotns er he i:r1 ftt leti:5t HOJ STANilQY 'N~thi11 the fte:,(;l ti hettrs flitn l iH COLD

~ithin the-mlfowi:ng 30 h~

T 4.6.16.. I OPERABl LITY of oildary Conl:!inmen! sha!J be di?monsttated at 1h frequency spec:ified iu lhe SllJ'veitlanc Frequency Control Pm.gram by 1,1erifying Lhat eacb iloor in each access openin is d olled except wbcn the access open.in,g is being used for 11on:nnl tram.it,entry and ex.[1..

.6:6.1.2

. t,he frequency specified in uh Survei,Uance Freq111.'tlC

'on.tro,1 h-ogr.un. verif).1 each Supp lementmy Leak Colle tion and Relea e System produc a: negative pressm of great~r than or equal l:o 0.4 inch wnter gaug in *th Auxili,ary BuiJding a:t 24'-6" el v11rian ~ iilhia.I:!.

.seconds after tart ign ~.

MILLST NE -. lT 3

+.B;~.

_".2j8-

Unit 3 TS Insert With the Secondary Containment inoperable, Serial No.: 25-301 Docket No.: 50-423 Page 2 of 2

a. If in HOT STANDBY or HOT SHUTDOWN, and STARTUP has not been entered following refueling, restore the Secondary Containment to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />; or

b. Restore the Secondary Containment to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

Serial No.: 25-301 Docket No.: 50-423 MARKED-UP TECHNICAL SPECIFICATIONS BASES PAGES FOR MPS3 (FOR INFORMATION ONLY)

Dominion Energy Nuclear Connecticut, Inc.

Millstone Power Station Unit 3

CONTAJNMENI SYSTEMS B

E 3}4. ),6.2 Serial No.: 25-301 Docket No.: 50-423 Page 1 of 5

'f'h Sec{l1t<lary -onm.inmen!l

• oomprised of the comainnJ.ent enclosur b1..1ildi11g mid. all co:rniguoui; bui]dings. main. sleam valve buildililg [partially], e.ngiim~ring safety feature buildiing (partial.l:y], hydrogen.FOCO!ilbi.oer building [parlia:tl. ], and auxil,i:iry bui ldin.. ). The s~oonda.cy Couln.i.t1menl s!'ial.l exist hem.:

a, Each door-iH each access open.1ng ~ dosed except wlien the ac es.s opmin_g is being used fo. noll'lllllll tr.m i1 entry and exit,

b.

Th s afing mechanism assa inited 'II '{h each p 11e1rarimi (.g. welcl:s.. bellow:, o O-rings) is OPERABLE.

• *-ondary ontainmenit ensures that till.? relea of diinactivc male"rials from !he primary c011L11inn1ent.aunosph.ere

'LI her.tricte.d to ilios leakage. paths and a&so.cia1ed leak rat asi,,.i11. d in1 1he a:fel:y analyses. Th.is re lr:iction, in eonj11Dclion w:ilh operation of llie S upplemenhlcy Leak

• oliedion and Rclea

• y~um1. and.uxiliary1 Buikli:ng Filter y rem ill Iin1il 1h fTE. BOUND RY radiation doses to wi"lhir:i the rl se !,'lLirleline valu of 10 CFR 50.67 dw:in.g accide:in ocmwtions.

The

• LCRS and the ABF fans and filtration unit are located in the auxiliary building. TI1 LCR is descnoodl in the Millstone

• nir I o. J FS R. ection. 6.2. 3.

ln mrl.er to erumre a negative pr sure i11 all areas\\,.*1!1in the e,i:oru:Ioory Con'taiil1trent uncter most meieomlagical comli1ioni, !:he negative pre sw-e acceptanc criterion at 'the 111easuredi location (i.e..., 24' 6" elevation illl the auxiliary building) is. 0.4-inches Yater gauge.

Th condary oniaim.nent OPERABILITY must be maintained to ensure pmp r op ration of tbe LCR and tile auxiliary buil<l.ing lille:r. stem and o limit radioacti e I aka~ e from the CQ:lltainment lo I.ho p;itb. and.leakage n tes assumed in th accident anal}

A1mlic-af.i.iiitv Main.taillling eoondal'}' Cou:tai.mue.nt OPERABJ.lJTY prevents leakag of ruaioaclive material from lhe econdary ontainm nt. Radioactiv marerial ma enter the Secondary ontafom nil from th. co.nminme-11l foJlowing a LO

. Th r.efore, &condary Con,taim:nerit is. requrired in MODE I, 2,. and. 4 when a design ha..*iis acddc11t sud:i as a LOCA oould release radiioa.tiv material t.o th conllrilllll 11.t allrno phere.

M!LLSTONE -

TJ R 3/46-7 AIDendme1lit No. 81-, _

.dRC Verbal

• ck11.o lwgment: ff7l05/ 7

BA ES 3/4.6.6..

YSTEMS Serial No.: 25-301 Docket No.: 50-423 Page 2 of 5 Tu MODES 5 and 6 d1e prdbabili,y a11d. conse-quetu;;es.of.a DBAare low due to the RC tem,perature and pressure. limitation in these MODES. Therefore ecot1dary Collitainment is not n:quireJ inMODES 5 and 6.

[n the e.,.ent Secoru:lary CMtainment OPER.AI:HLITY is. 11ol m:ainitained, Secondary Coutainmefll OPERA8ILITY must be res.ta.red i,vithw 24 hoW:,!:'.-Twenty-four hours *.i a r1::-asonable Completion T1me consi.deri t1g the limitecl leak..1:ge design ofcontai:nment and' the low probabiri ofa DBA,occuning during lhi time per1od.

Unit 3. Bases lnserl IBo:perab1lity pf the Secondary Containrn nt docs not make the LCR. fans and filte *~

inoperable, Therefore; wh tle

• i:n th.is ACTION Sta.temer;it-solely ilu to moperabi'lity of the

• econdary Containm~nt,. tl'1e,oondirions.aud requireJ ACTiO, S associatedw,ith Speci-fic:nion

",().. ()_ I (i.e... uppleineutary l.eak Collecfiotl am! R'.el~se System) are not t-cqui.red to be-ntered.

lfthe S 1.."-0ri.dalJ' Cor1tai1nnet1t OP'ERABILJTY caoo.ot be restored to OPERABLE statmrw.ill:tin th.e.req1ui.red oomplet1on time the plant. mu:,.--t be bn~ugh,t to a MODE i 11 whi h. the LCD does not apply. To achieve this 1m1tus, th.e plan,t must be brought io at I,am M

• DE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and lo MODE 5 within. be fol l,ow:ing JO hour&. The a!Io,;ved Completion Time are reasomjble, based on qp *ratillg--expeci nee, to reach 1he requ.icrod plant con,Ht.ious from full-power condition 111. an orderly manner and witibout challenging plant systems.

Si.mre.illam::e Requiremi!ntl

.6.,6.1.1 t\\..faintaining SeeondaryContai11rneru. OPERABIL1TY fequire maiuta'ii:1ing acl1 door i1i each acces,! opeafog in a clo ed :positiotl ex.cEWt when.tile ace opemng is being usoo for normal entry and e'.ltit. The normal time a llow:ed for passa"e of equip1nent and per.:soru1el through each a ca s op,e11ing aJ. a time i, deffoed as 110 1110Fe than 5 minutes. Thie a~.cess opening shall n.ol be blo0ked open. During this time it, i

• riot con idered neces ary lo e.rn:er the ACT[O I statemei1t A 5-minute time Is. considered accepta[)le since fhe ace.. open.ing can be quickly clo~d without

.. pocial pm vi ions.:,tml the p:roha:bili ty of occurrence of a DBA cQ11ourren1 with e,q11 ipme:nl an m personnel tnm i.t time of 5 nu:mrt is Im _

Tfae* surveillanc*e frequenc is 0011trolled tmder tire urveilfunce reqllency Control Program.

MILLSTONE - *, T 3 B '4. 6-8 mendme.nt No. 8+, H6

BAE l contioocd')

Serial No.: 25-301 Docket No.: 50-423 Page 3 of 5 The ability fa

• L. RS to prod11ce. tbe.equired. neg;iti,

• pressure d1rdng 11:1 t !l operati011 within lh required 1:iim provfdi5 ass.l..ir:m e d.1:al: the cco1ioo Containment is adequ11Jtel sealed.

11 1.th the SLCRS in postaccident configuration, the.required.. negative-pressure in the econdaiy Cmna.inmel!lt is achie,,"Cd in I. I. 0 seconds..from th.il tim.e of simulated eJrnergency diesel get'leratorr breaker closw:e. Tim delays of damp rs,mrl logic d lay* must be accountecl for in thi S.tm"eillance. Tiie thne to,achie1r*e the required negati,\\ pressure i l20 s.eoolild& wid1 a 1o -of-off Ole power ofoddenl wi th a. SlS. Th sul'Vllilla[l ve.rifi~ that cme l:rnin of SLCRS in conjUJ1c:li n wtth tl:ie ABF !!l}'Stem w.iU produce all!egariv.i.Pres.Sur

• f0.4 inch water gauge al the 11uxibary lmildililg; 24',6 ' le,,aria.11 relntive to th oursid atmo phere in the-ecom:wy Ctmtai:umenl. or tllle purpose of this iru.rveiil.ance. _pre55ure mensureme:nls. will. he made at the 24' 1" el. vatfori. in the a.u:xiliacy building. This. si.ngie location i oons1cle.red. to be adeq1113,te :md repr,_"'Sfillralive of the entire Se oudary Cm1tainment du to lbe large cross-. ection of tl1e *air prn.-Sll"'

which intercarmect the various btiildlings \\! ithin 1he Secondary Contninmen,t. Jn oro to mure o. l!legati pr sure.in all are~ insid. the &eco.llaaJ)* Com.aimn nt lll.lild r moot.

me:reoratogical cond:iuons _ l.h.e aegati.ve pre s11re acceptll.Tic,e criterion at th meamred location is O.<I* inch warer gauge. It is recognized that there wiJl be an m::casiomd meteorological coad!itim1 1u1der, hi.:11 s:lignlly posi1ive pressure may exist at.some localized portions ofth-e boundn * (e.g.

th -upper e*levat[ons 011 the downawind side,of a bwldi:ng). For e:ica.mpl, :i very low outside temperature eombin~d. \\\\oith a mod fl:-ate wind :;;peed could cause a. sliighdy positive _pressu:re at the upper Jev.arioois ofrhe.containme1;1t encloSl.lnl bu.i:Iding-on i:he l.eeward. face. The pmbabillty of occurrence of m oorotogi'cal com:litioM which 011ld re U!lt in such a pos.1,tive cliff, r.mti.al pressure

.o:ndition i.n the opp r le--.,els oft.h.e:-en !osmre buildi1:1g has been 1ima1.ed I.a be. less Lhan % of diebme.

Th. probability of wind speed w:ithiin the ReCL'SS.ary nIDderat" b::md, oon1bined with th prob:rbi Ii. of xtreme low tern.pe:ratme, ootubinecl,vith the sma.ll ~ortion of th oom1rlary affected, combined with the.low probabilil of airbome radioactive material migrating to i:he 11ppt'f level eJr1sures that t:h overall effect on th,e design ba i dose calru.la:tim

• is lllSLgni.lic:mL The LCR s.y t.em a:nd ran si.ring was bm ed 011 an estimated infi 11:ration rate_ Th.e f.an Ho, rates are verified wi1Jai.Jr1 a minim:um and. ma..--::.iml.lll!ll on. a monthly basis. l.nitiid test:in~ verrfied that the drawd:own,criterion, as met a we lowest a,cceprabJe flow.rate. he n,e v standard Tcchuica.l

• peci1lcatiolll (NUREG-1.43 l 3...2 suJrVeillance reqwremel'!t requi.re.o; th.at Lhe cli:a"-'GOWll Ml1LSTONE - UNIT 3

.8 3/4 )*

Amendment,

. 81 12

.BAE 3/.Ui6.2 Serial No.: 25-301 Docket No.: 50-423 Page 4 of 5 criteiion b met, hil.e not eX'ceed.ing a ma."::"i1num flov

• rate. U i' assumed thac the purpose of t1'1i tlmv limit is to n ure that mlequate attention i given to mafolai.n the.. [

~

houn.dary iniegr.ity and not usi.ng ::u::ess s., lem capac.i,t to rover for boundary degradation.

The L RS system was designed with minimal n:mg-in and. therefore do not have excess capac:-ity (hat c,an be sub~tit11ted for boundary in1.egrity. dditionall * !.1ne11: SLCRS fa1:1 flow ntes a v dfi d. to be acceptable on a more frequent basis tl1an th.e drawdmvn test survciUan and b means of previous testi t1g the minirulJTTI How rm is acceptable, ve,rifyin

• a flow mte cll11:ring the dra.v dow:n lest would n t pr-0vide an ad.ded. benefit. Hist.o:rical SLCRS flow me

• m:emerat

• show a lack of l."epeal:ability ~sociated with ti! *rnaccui.1

• of tµt* ffo,v m.easureme1:1t As a resu14 tb more 11

• fi h1 verification of !:.'J t m perfo:r.wauce is lhe.iet1:ll11 negative pressure."enerated h the drawd! wn test,and :i mea:rurcd flow rate-wo11lcl add Ii tde_

EOO~"DARY CONTA

• Thi limitation ensures that lih trootural i:nregnty of the eoorulai*y Containment will be maintaiued comparable to the origi.nal desi o s:taud:rril. for the life ofthe facility. tructural in, grit)* is uq11.ired to pro.*.ide a s:e-co:mfary boundary surrouuding dre primary contailnnenl th'li1 can be maintained at a.negative pressure durio.g accident oollditioas. A * ':i.1a,I in pection is sufficient lo demonstra.te this capabilit.

MILL TONE - : IJT 3 B 3/46-10

Unit 3 Bases Insert Serial No.: 25-301 Docket No.: 50-423 Page 5 of 5 If the Secondary Containment is inoperable, it must be restored within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

However, If the Secondary Containment is inoperable in HOT STANDBY or HOT SHUTDOWN, and the unit has not entered STARTUP following a refueling, Secondary Containment OPERABILITY must be restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The Secondary Containment is allowed to be inoperable for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> instead of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> immediately following a refueling when the reactor has not been critical because of the reduced decay heat generation and radionuclide inventory, the limited leakage design of the containment, the OPERABLE TS systems in the applicable MODES, and the low probability of an event requiring the Secondary Containment.