ML20212D176

Application for Amend to License NPF-39,revising TS Section 3/4.1.3.6,to Exempt Control Rod 50-27 from Coupling Test for Remainder of Cycle 7,provided Certain Conditions Are Met

ML20212D176
Person / Time
Site:	Limerick
Issue date:	10/24/1997
From:	Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20212D181	List: ML20212D176 ML20212D185
References
NUDOCS 9710310028
Download: ML20212D176 (9)

Text

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st uonsupporto.portm.nt 10CFR50.90 PECO NUCLEAR nco s o c -

'?  : A Ow or PECO $mucy ' $$$$$$

Wayne. PA 19087-5091 October 24,1997 e Docket No. 50-352 License No. NPF-39

' L U.S; Nuclear Regulatory Commission -

' Attn: Document Control Desk

Washington, DC 20555

Subject:

Linierick Generating Station, Unit 1 ._

Technical Specifications Change Request No. 97-05-1

Dear NRC Officials:

PECO Energy Company is submitting Technical Specifications (TS) Change Request No.97-051, in accordance with 10CFR50.90, requesting an amendment to the TS (Appendix A) of Operating License No. NPF-39 for Limerick Generating Station (LGS), Unit 1. This proposed N

change will revise TS Section 3/4.1.3.6, " Control Rod Position Indication," to exempt control

- rod 50 27 from the coupling test for the remainder of Cycle 7 at LGS Unit 1, provided certain conditions are met. :Information supporting this TS Change Request is contained in

, - Attachment 1 to this letter, and the marked up pages showing the proposed change to the LGS Unit 1 TS are contahed in Attachment 2. This information is being submitted under affirmatica, and the required affidavit is enclosed.

~ We request that, if approved, the amendment to the LGS, Unit 1 TS be issued as soon as possible, and become effective within 30 days of issuance.

.lf you have any questions, please do not hesitate to contact us.

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Very truly yours, f.

. G.1 A. Hunger, Jr. 14 Drector- Licensing

= Enclosure, Attachments 4'

cc 3 LH.J.Milpr, Administrator, Region I, USNRC (w/ enclosure, attachments)

A.L.Burritt, USNRC Senior Resident inspector, LGS (w/ enclosure, attachments) l

R.R.Janati, PA Bureau of Radiological Protecthn (w/ enclosure, attachments)

' $9710310028 971024 ~U

>PDR ADOCK 05000352f P' 'OR5 h ,. - . __ _ _ . . . _ _ . _ . . . , - - .,

1. . 'O COMMONW5ALTH OF PENNSYLVANIA  :

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-' COUNTY OF PHILADELPHIA  :

9. B.- Cction, being first duly sworn, deposes and says:

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That he is Vice President of PECO Energy Company, the Applicant herein; that he has read the foregoing Application for Amendment of Facility Operating License

. No. NPF-39 (Technical Specifications Change Request No. 97-05-1), to exempt control rod 50-27 from the coupling test for the camainder of Cycle 7 at LGS Unit 1, provided certain conditions are met, and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, <

information and belief.

Vice President s

1 cSubscribed and sworn to -

before me thisd[ day-

,, cof) 1997.

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• NOTARIAL SEAL carol A. WALToN. Notary Pubte

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4 ATTACHMENT 1

.,p . ': LIMERICK GENERATING STATION

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7 UNIT 1 g '

A; DOCKET NO. 50-352

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LICENSE NO. NPF , ev' ' Ii j_'s 1

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TECHNICAL SPECIFICATIONS CHANGE REQUEST

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'?  : NO. 97-03-1 <

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zu Supporting Information for Change - 6 Pages

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M " TEMPORARY--SUSPENSION OF REQUIREMENT '

TO FULLY INSERT AND DISARM u

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- CONTROL ROD 50-27 IF UNCOUPLED"

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, ,; []9e Docket No. 50-352 License No. NPFo39

>.1 PEDO Energy Company, under Facility Operating License No. NPF-39 for Limerick i

Generating Station (LGS), Unit i requests that the Technical Specifications (TS) contained in Appendix A to the Operating License be amended as proposed herein, to ,

- revise TS Section 3/4.1.3.6 to exempt control rod 50-27 from the coupling test for the l

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remainder of_ Cycle 7 at LGS Unit 1, provided certain conditions are met. Unit 1, Cycle 7 is currently scheduled to end in April 1998.

. _L The proposed change to the LGS, Unit 1 TS is indicated by markups on TS pages 3/4 1-11.and 3/41-12.LThe TS pages showing the proposed change are contained in Attachmerd 2.

i iWe request _that,'_if approved, the_ TS change proposed herein be issued as soon as possible, and become effebtive within 30 days of issuar,ce.

oThe'NRC has previously approved similar TS changes at Peach Bottom Atomic Power 4 Station (PBAPS), Unit 3 by letter dated July 10,1991, and LaSalle, Unit i by letter L dated February 3,11987.-

%This TS Changs_ Request provides a discussion and description of the proposed TS s . change, a safety assensment of thel proposed TS change, information supporting a -

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• Afinding of No Significant Hazards Consideration,' and information supporting an

Environmental Assessment.

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?ey 1 1 Dim =. ion anr1 Description of the'Prooosed Chanae J he proposed Technical Specifications (TS) Change Rec,uest will revise Limerick Generating Station (LGS); Unit 1'TS Section 3/4.1.3.6 to exempt control rod 50-27 from tthe coupling test for the remainder of Cycle 7 at LGS Unit 1, provided certain conditions

are met <

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- On August 31,1997, during the weekly exercise test of control blade 50-27, when the -

blade was inserted one notch from the full-out position 48 to position 46 and then

• l rsturned to full out, the full-out position indication of 48 was lost. A continuous 4 -withdrawal signal was selected to restore position indhation which resulted in a " rod i overtravel" alarrn, indicating de-coupling of the drive from the control blade. In accordance with existing procedures, power was reduced to below 60%, followed by full insertion of blade 50-27 to position 00 and its being disarmed. Upon subsequent frl, - troubleshocting, the blade _was fully withdrawn (again, without receiving position

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' indication for the full-out position of 46) Blade movement was verified during the withdrawal by monitc, ring Lncal Power Range Monitors (LPRMs). The blade was t judged to be coupled since an overtravel alarm was not received following selection of a continuous withdrawal signal after the blade was judged to be fully withdrawn; however, since the full-out position indication of 48 was not received, the blade could

' inot procedurally be' determined to be coupled and was therefore re-inserted fully to n y position 00 and disabled by hydraulic block in accordance with TS requirements.

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, '(" A Docket No. 50-352 Ucense No. NPF 39 i

. i c.) Limking Condition for Operation 3.1.3.6.a.2. requires that if recoupling is not

' accomplished in the first attempt, the rod is to be declared inoperable, fully inserted, (and disabled electricolly or hydraulically. Survnills.1ce Requirement 4.1.3.6.b. requires

/ that the coupling test be performed any time the control rod is withdrawn to the full out M, ,

• p position. The only way to verify rod coupling, as descrit,ed in existing plant procedures

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f ' '(Control Rod Exercise and Control Rod Coupling Check) is to fully withdraw the blade

? : to position 48; and then apply a continuous withdrawal signal to verify that no overtravel alarm occurs. By the nature of the problem with blade 50-27, an indication

.- of 48 cannot be received; hence, it cannot be positively ascertained that the blade is

'9 fully out in order to apply the withd:awal sigrwi to check for overtravel. Since the blade t

4 ,_ con not be assured of being'cou@ d, it must be assumed to be not coupled. Tha '

f proposed TS change would suspend the requirement to fully insert and disarm the

' subject blade for the remainder of Cycle 7 at LGS Unit 1.

iThe proposed Technical Specifications (TS) Change Request will revise Limerick

'G/ Generating Station (LGS), Unit 1 TS Section 3/4.1.3.6 to exempt control rod 50-27 from y.J (c . l the coupling test for the remainder of Cycle 7 at LGS Unit 1, provided certain conditions yg q.

m A iThe followind TS changes are proposed:

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, ?4 11.L Limiting ConGion for Operation 3.1.3.6.a.2. has the underlined phrase added:

If'recoupling is not accomplished on the first attempt or, if not permitted by the RWM, T ,

.then except as in 3.1.3,6,d or until permitted by the RWM, declare the control rod inoperable, insoft the control rod and disarm the associated directional control valves either

(The balance of this paragraph remains unchanged.)-

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[j T l2[ Limiting Condition for Operation action 3.1'.3.6.d. is added:

',J' (d.)For control rod'50-27, for the remainder of Unit 1 Cycle 7, if coupling can not be

4 established the uncoupled ~ rod may be' withdrawn when rated thermal power exceeds

!10% ony.'f all the following conditions are satisfied:

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. Lfg The' uncoupled control rod may not be withdrawn past notch position 46, and 1 ~ f 2)1No other uncoupled centrol rod is withdrawn.

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[ 3.0 Surveillance Requirement 4.1.3.6.d. is added:

, ;d.~ When repositioning the uncoupled control rod per Specification 3.1.3.6.d the uncoupled rod's position shall be verified to have followed the control rod drive by neutron instrumentation (LPRM or TIP). If the control blade can not be verified to have v ,

_ ; followed the drive out to its final position, then the rod shall be completely inserted and b ' '

the control rod ' directional valves disarmed as stated in 3.1.3.6.a.2.

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Docket No. 50 352 ff '

License No. NPF 39 f ..

1.[The reason fdr operating the blade in the near full-out position of 46 is to minimize the Sp: ! s, TE3ei opersilon of the core and resultant reduction in thermal limit margin that occurs with the subject blade fully inserted. I g '

d hy j m 10 Safety Assessment

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{ The primary concern for control rod _ coupling integrity is its impact on the potential

_ increase _in the~ probability of a Control Rod Drop Accident (CRDA) as analyzed in the

' L Shfety Analysis Report (SAR).- Procedural changes include full insertion of the subject blade during reactor operation below 10% rated thermal power, whers the CRDA is a

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concern. For occurrence of a CRDA, the drive and control blade must be uncoupled, ithe drive 'must be withdrawn with the control blade otherwise retained in its inserted gg

" . position land then me blade must be subsequently released, falling to the position of

,the drive. Above 10% rated thermal power, the consequences of a CRDA are (negligible, and no restr_ictions on control rod position are required even if the drive and g

blade can not be verified to be coupled.- Therefore, the subject t lade and drive will .

remain fully inserted during any reactor operation below 10% of ' rated thermal power, I Teliminating any consequences from a postulated CRDA.

[ iA secondary concern related to~a potential uncoupling is the inability to ascertain

, control blade position. Since the position indication dispSy is an indication of drive

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_position, the indication may not be an accurate reflectiois of blade position if the drive W' '

' land blade are uncoupled. To minimize the effect of this, during blade 50-27 withdrawal Labose reactor thermal power of 10%, neutron flux information in the vicinity of the blade Jwill be' monitored via' Local Power Range Monitors (LPRM) or Traversing In-Core Probe e

. i(TIP) to verify that the blade tracks with drive movement.1 This will ensure the blade is

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a not sticking and is not separated from the drive.- It is not credible that a withdrawn, uncoupled control blade could be buoyed upward into the reactor core; the velocity limiter at the base of the blade is shrouded by the guide tube and is not subject to lifting force due to core flow.E Cooling flow from the control rod drive pumps averages

, _ approximately 1 gpm per. assembly and is insufficient to overcome the weight of the control blade and velocity limiter.

O l Another concern is potential equipment damage from scram loadings. With the drive in

@"g/ 1s' withdrawn position and the blade not coupled to the drive, following a scram initiation,

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< the blade could become separated from the drive during the deceleration phase near 1 the top'of the scram stroke. This'woulo allow the blade to centinue traveling upward, f with the velocity limiter impacting the bc ttom of the fuel support casting. This may y" : cause damage to the velocity limiter, and upon rebound, to the' drive spud and blade Elock plug; however, GE has determined that there is insufficient energy to dislodge the 1 fuel support (or tuel) or to cause a threat to the pressure boundary integrity. This poterdial for damage to the velocity limiter and/or spud is not a safety concern: the function ~of the velocity limiter is to control the free-falling speed of a control rod during a CRDA.' The subject rod will not be withdrawn below 10% thermal power where the 4 effects of a CRDA ar;e significant, therefore postulated damage to the velocity limiter 3

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, Docket No. 50 352

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LkGnse No. NPF 39 jjpp _ ,

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v has. no adverse safety consequence. _ Damage to the drive spud or blade lock plug,

pcardkg their function to couple the drive and blade, is not consequential since they are assumed to be not coupled, and the described mitigating actions assure no adverse effects from the uncoupled condition. The potential for damage to the velocity S L IW and/or spud can be minimized by not scramming under cold depressurized oork,itions, and scram testing, if necessary, from the lowest achievable withdrawn

_ pot} tion.< Scram and insertion performance are not considered to be degraded by 3 # operating with the blade in position 46 since negative reactivity insertion characteristics ' l

are'slightly improved by starting the scram motion from a slightly inserted position.  !

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- Therefore, it is concluded that operation with the subject control blade withdrawn to a <

near full out position of 46 does not lead to any condition adverse to reactor safety.

1 Information Supportiria a Findino of No Sionificant Hazards Consideration

^'s s We hive concluded that the proposed change *o the Limerick Generating Station

, i(LGS),LUnit 1 Technical Specifications (TS) which will reviss TS Section 3/4.1.3.6,

" Control Rod Position Indication," to exempt control rod 50-27 from the coupling test for

g. T the remainder of Cycle _7 at LGS Unit 1, provided certain conditions are met, -

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., does not involve a Significant Hazards Consideration. In support of this determination,

, . Ten evaluation of each of the three (3) standards set forth in 10CFR50.92 is provided below.

,1i , The orooosed Technical Soecifications (TS) chanae does not involve a -

isianificant increase in the probability or conseauences of an accident oreviousiv evaluated.

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, 4 t The probability of occurrence of the analyzed Control Rod Drop Accident -

- (CRDA) is not increased by operating with the subject control blade in a -

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, . condition not known to be coupled since the compensatory measures will assure

, that the blade will remain fully inserted below 10% rated thermal power where  !

< the CRDA is a concern _ Monitoring of nuclear instrumentation responses in the .

(vicinity of the blade when the drive is withdrawn above 10% power will assure Ithe blade is tracking with the drive with no potential to stick and then drop, b ,

Scram impact forces from an uncoupled control rod are of insufficient energy to

, , dislodge the. fuel support (or fuel) or to cause e threat to the pressure bouridary

integrity. No reducticn of system or equipment redundancy is involved.

. The CRDA analyzed in tha Safety Analysis Report (SAR) remains the limiting rod drop accident, and its consequences are unaffected by operation of the 20 i. subject blade in the proposed manner. Operation of the control blade as O; described, i.e., withdrawn no further than the 4S position and in a condition not jdh '

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known to be coupled, has' no adverse effect on scram performance in response

[  ; to sny other postulated accident. The scram insert motion of the rod is not J*

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Docket No. 50 352 License No. NPF 39

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'(.M gg m y # affected by the'potentially uncoupled condition, and since the rod is alretdy 4 < partially inserted at position 43, it should have a slightly better negative reactivity i N insertion characteristic. 5herefore, no potential to increase onsite or offsite radiological consequences beyond those previously analyzed in the SAR is 1

created.

! . Operating the subject control blade in a condition not known to be coupled does '

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. [not result in any onsite or offsite rad _iological consequences different from those

, g previously analyzed in the SAR. The subject control blade will be fully inserted -

below 10% thermal power where the CRDA is a concern and will be monitored

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.1 during _ drive withdrawal above_10% thermal power tp assure it is tracking with y the drive. Scram performance is not adversely affected by operation from the M f 4 near full out position of 46~ Hence, no new failure modes are created and

,,1 consequences of any postulated failures are not increased.

1 Therefore, the proposed TS change does not involve an increase in the probability lor consequences of an accident previously evaluated.

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• , _ Y 2 2.J (The crocosed TS chance does not create the oossibility of a new or different -

4 kind of accident from any accident oreviousiv evaluated.~

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%_ i 1The Safety Analysis Report (SAR) analyzed Control Rod Drop Accident (CRDA)

. remains the only type _of accident initiated (or contributed to) by the control rod K

e (drivetcontrol blade interface. The compensatory actions to be taken~when 4

, operating the subject blade in a condition not verified to be couplod assure that

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'! ' _  % no new types of accidents can occur.The subject control blade will be fully inserted below 10% thermal power where the.CRDA is a concern and will be 2

W monitored during drive withdrawal above 10% thermal power to assure it is g , tracking with tha drive.' Scram performance is not adversely affected by

,fa? operation from the near full-out position of 46. Since no adverse effect o,

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insertion or scram performance is expected, the previously analyzed accidents y , encompass any potential consequence of operating with an uncoupled control

%D j p tlade!

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<; V P: The compensatory actions to be_ taken when operating the subject blade in a m condition not verified to be coupled assure that no new failure modes are T (created,' and, therefore, no new type of equipment malfunction is introduced by

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• operat_ing tho' subject control blade in the proposed manner.

g y~ Therefore;the proposed TS change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

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Docket NA 50-352

.;, w p 4 License No. NPF 39 Al ym L.i 3,1 5 The crocosed TS chance does not involve a sionificant reduction in a maroin of

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k~~# t Operation with the subject control blade in a condition not known to be coupled Lfor the' remainder of Cycle 7 at LGS Unit _1, but with the compensatory actions

_ ~J < described below, does not reduce the existing margin of safety determined by m (the analysis'of the Control Rod Drop Accident (CRDA). The CRDA analyzed in t

nths Safety, Analysis Report (SAR) remains bounding in that the subject rod will- l 1  : be fully inseded below 10% rated thermal power whus the CRDA is a concern.

l' Above 10% power, when the associated drive is withdrawn, the nuclear instrumentation in the vicinity of the blade will be monitored to assure the blade tracks.with the_ drive; providing assurance that the position of the blade can be g:yl ascedained by the drive position. If the control blade can not be verified to hove W

followed the drive, then the rod shall be completely inserted and the control rod 1 directional valves disarmed in accordance with existing TS requirements. To

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minimize any scram impact loadings, the blade will be operated at the near full-  ;

e. ;out position of 46 except for intermediate posi;icns temporarily occupied during l

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standard rod withdrawal sequencesc Operating the subject control blade in the

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• proposed manner will have no adverr.e effect on insertion or scram performance

, of the blade and will preserve the margin of safety._

'. *5 Therefore, the proposed TS change does not involve a reduction in a margin of

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Isafety. .

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3 informatiqn Sucoortino an Environmental Assessment LAn environmental assessment is not required for the change prop > sed by this TS 3

4~ Change Request because the requested change to the Limerick Generating Station

- - (LGS), Unit 1 :TS conforms to the criteria for " actions eligible for categorical exclusion"

Las specified in 10CFR51.22(c)(9). - The requested change will have no impact on the W

environment. LThe proposed change does not involve a significant hazards -

ga consideration as discussed in the preceding section.- The proposed change does not Gl "

involve a significant_ change in the types or significant increase in the amounts of any effluents that_ may ba released offsite. In addition; the proposed change does not

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inv64ve a significant increase in individual or cumulative occupational radiation SMposure.

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Adonclusion

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(The Plant Operations Review Committee and the Nuclear Review Board have reviewed

> this proposed change to the Limerick Generating Station (LGS), Unit 1 TS and have x concluded that it does not involve an tinreviewed safety question, and will not endanger ithe health and safety of the public.

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