ML20077E194

Application for Amend to License NPF-29,deleting Several Refs to Operation of Reactor Recirculation Sys in non-loop Manual (Automatic) Mode of Flow Control

ML20077E194
Person / Time
Site:	Grand Gulf
Issue date:	05/30/1991
From:	Cottle W ENTERGY OPERATIONS, INC.
To:
Shared Package
ML20077E175	List: ML20077E166 ML20077E194 ML20077E197
References
NUDOCS 9106060214
Download: ML20077E194 (6)

Text

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1 BEFORE Tile UNITED STATES NUCLEAR REGULATORY COMMISSION LICENSE NO. NPF-29 110CKET NO. 50-416 IN Tile MATTER OF MISSISSIPPI POWER & LIGitT COMPANY and SYSTEM ENERGY RESOURCES, INC.

and SOUTil MISSISSIPPI ELECrRIC POWER ASSOCI ATION and ENTERGY OPERATIONS, INC.

AFFIRMATION I, W. T. Cottle, being duly sworn, state that I am Vice President, >

Operations GGNS of Entergy Operations, Inc.; that on behalf of Entergy Operations, Inc. , System Energy Resources , Inc., and South Mississippi Electric Power Association I am authorized by Entergy Operations, Inc. to sign and file with the Nuclear Regulatory Commission, this application for amendment of the Operating License of the Grand Gulf Nuclear Station; that I signed this application as Vice President,tOperations-GGNS of Entergy Operations, Inc.; and that the statements made and the matters l set forth therein are true and correct to the best of.my knowledge, information and belief.

w F C-W.'T. Cottle STATE OF MISSISSIPPI l COUNTY OF CLAIBORNE SUBSCRIBED AND SWORN TO befor me, a Notary Public, in and for the County and State above named, this- -day of TT C , 1991, d

(SEAL) crbMa bnbnn% ~

Notary p>l Mg'commissionexpires:

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A. SUBJECT

1. NPE-90/02 Removal of References to the Non-1.oop Manual Flow Control Mode of the Reactor Recirculation System

2. Affected Technical Specifications:

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a. Figure 3.2.3-1, HCPR , Page 3/4 2-5 7

b. Figure 3.2.4-2, LUGRFAC , Page 3/4 2-7b f

q c. LCO 3.4.1.1.b.2, " age 3/4 4-1

d. Action Statement 3.4.1.1.g, Pagn 3/4 4-la

! c. Surveillance Requirement 4.4.1.1.3, Page 3/4 4-la

f. Bases 3/4.2.3~ ' ages B 3/4 2-4, 2-4a, and 2-6 4

g. Bases 3/4.2.4, Page 3/4 2-7 E

h. Bases 3/4.4.1, Page B 3/4 4-1 B. DISCUSSION i 1. Entergy Operations, Inc. is requesting revisions to the Technical Specifications (TS) and Bases which make reference to

or infer operation of the Reactor Recirculation System in the Non-Loop Manual mode of flow control. This mode of operation -

has been permanently disabled by a control circuit design change implemented during the fourth refueling outage.-

.2. Prior to the design change, the reactor recirculation flow control system was capable of controlling the two loop flow-control valves either individually in Loop Hanual (manual)~

control or in unison via Non-Loop Manual (automatic) flow control. The automatic mode was comprised of~ circuitry which adjusted total core flow via simultaneous signals to both-valves. This maintained either an established turbine-generator demand, a desired reactor neutron flux level, or a set total recirculation drive flow, depending upon operator preference. :

The Non-Loop Hanual mode was removed by permanently installing wiring which prevents transferring the flow control system out

-of the Loop Manual mode under any circumstances.

, 3. This design modification was made because it was determined that operation in the automatic flow control mode, while originally intended for operational flexibility, provided little or no benefit compared to manual operation. In fact, having the-capability to employ Non-Loop Manual flow control resulted in several inconvenient and costly requirements being placed on plant operation and maintenance. It was also=necessary to perform additional plant transient analyses specifically addressing. this mode for. each reload.

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3 4. ' Marked-up TS:and Bases pages ret'lecting the desired changes are 4

attached.

5. A minor editorial change is also being made to Bases Page B-3/4 2-7a. This change deletes the continuation heading atop the page to correct an editorial error made in Amendment No. 73 to NPF-29.

C. JUSTIFICATION

1. The Non-Loop Manual flow control mode of the Reactor

Recirculation System was' permanently disabled during the fourth l refueling outage in order to accommodate the plant operating ,

staff's preference for system operation exclusively in the Loop i Manual mode. A number of reasons were identified for this prefererne, including compatibility with core monitoring software, reduction in I&C maintenance and calibration efforts, and increased operating margin thermal limits gained through less restrictive reload licensing analyses.-

4 A design change was implemented to accomplish the required .

circuit modifications. Prior to installation, this. design change was reviewed against the critoria of 10CFR50.59 and determined not to be an unreviewed safety question. It-was also determined that a TS revision was not required prior to making the change since no operating conditions or actions in the TS require that the system be placed into: the Non-Loop Manual J

mode.

2. In the determination of the. Cycle 5 thermal limits for. Linear j

llent Generation Rate (LilGR) and Minimum Critical Power Ratio (MCPR), analyses were performed for both Loop Manual and

] Non-Loop Manual operation. TS Figures 3.2.3-1 (MCPR,).and i 3.2.4-2 (LilGRFAC,) nach contain curves reflecting both modes.

The curves in ca6h TS Figure for Non-Loop Manual mode are<being deleted by this change. These curves'aro not required since this mode of flow control is no longer possible.: .This change in-no way affects the basis or availability of:the correct thermal:

operating limit information. In fact, deletion of.the curves'

] reduces the possibility of unintentional- use of an incorrect -

curve, as well as removing superfluous, unnecessary-information.

Additionally, Non-Loop Manual operation after Cycle 5,will.not be supported by reload analyses and the curves. cited above will likely be inaccurate.

3. The Bases discussions oflthe above thermal operating-limits curves (Dases 3/4.2.3 and 3/4,2.4) are also'being modified toi

. reflect the disabling of.the Non-Loop Manual mode. This is necessary to ensure that the description of Lthe derivation and .,

basis of those curves is-accurate and~ complete.

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4. TS 3.4.1.1.b.2 requires t hat single recirculntion loop operation be conducted in thn Loop Manual flow control mode only. In addition, Action g of TS 3.4.1.1 states 7 the steps to be taken in the event flow control is determined not to bo in the manual mode, and Surveillanco Requirement 4.4.1.-l.3 apecifies the criteria for determining that flow control .in.the operating loop l

, is in manual. This change will delete these portions of j TS 3.4.1.1. ,

4 The design modification discussed in C.1 above permanently

disabled the Non-Loop Manual mode of flow control. This was i done by installing wiring which. electrically prevents transferring out of the manual mode with the controls availablo to the operator. Intentional or inadvertent operation in the aut.omatic modo is thus not credible without physical hardware changes to the control circuitry.

i Since it is now not physically possible to operate in other than t.he manual modo, stipulations requiring Loop Manuni flow control while in singin recirculation loop operation are no longer

] necessary. This is also true of the surveillanco-verifying manual flow control. This change does not affect the validity of the analyses supporting single loop operation, or in any way relax the requirements which must be met in order to operate-

! with one recirculation loop out of service.

5. Dasns 3/4.4.1 must also be revised to reficct the above changes. .

This is necessary to ensuro that the description of the analysis of single recirculation loop operation is accurato and complete.-

6. There are currently no TS which requiro or rely on operation of the Reactor Recirculation System exclusively in the Non-Loop Manual modo. The ability to operate in this modo is not needed_

to ensure that the assumptions of'any applicable safety analyses s remain valid. The changes requested are intended only to 4

onhanco the clarity and accuracy of the affected Specifications

- -and Bases by deleting references to automatic flow control which  ;

may prove confusing or misleading now that this, modo is .no longer availabin. Thus, thosn changes are considered to be administrative.

D. NO SIGNIFICANT HAZARDS CONSIDERATION-

1. Entergy Operations, Inc, is proposing.that TS 3.2.3, 3.2.4 and-

-3/4.4.1.1.be revised to reflect administrativo. changes-caused by3 the climination of the Non-Loop Manual flow control mode' of the -

Reactor Recirculation System. _Those revisions. remove references to the Non-Loop Manual flow control mode which state or imply

- that this -modo is available for use.

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2. The Commission has provided standards for determining whether a no significant hazards consideration exists as stated in' .

10CFR50.92(c). A proposed amendment to an operating license involves no significant hazards 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; or (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.

3. GGNS has evaluated the no significant hazards considerations in its request for a license amendment. In accordance with 10CFR50.91(a), GGNS is providing the following analysis of the proposed amendment against-the three standards in 10CFR50.92.

The hardware modifications made to the flow control circuitry have also been evaluated separat ely and found acceptable as part of the GGNS design change process per the provisions of 10CFR50.59

a. No significant increase in the probability or consequenc(s of an accident previously evaluated results from this change.

4 The Non-Loop Manual mode of operation has been permanently removed and it is no longer possible to operate the Reactor Recirculation System in automatic flow control. Thus, only those plant transient safety analyses which assume manual.

recirculation flow control prior to and during Reactor Recirculation Flow Controller Failure events now apply. The proposed TS changes simply remove references to the use of the automatic flow control modo throughout the TS. The proposed changes in no way increase the. likelihood of a Flow Controller Failure event necurring or make the results of the event analyses more severe. Continuous operation in the hoop Manual mode only may actually. decrease the probability and consequences of the_ analyzed events. This-is due~to less active equipment involved in-the manual modo, as well as only one recirculation loop being_ postulated to fall-Instead of two as when operating in t'.ie Non-Loop Hanual mode. The changes are administrative in nature since th~ey-

, are only removing'information and requirements that are no longer consistent with plant design.

Thus, the probability or consequences of previously analyzed accidents are not increased.

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b. The change would not create the possluility of a new or different kind of accident from any previously analyzed.

Both the Loop Manual and Non-Loop Manual modes of operation ,

have been previously analyzed / evaluated and approved. The proposed changes make the TS consistent with. current plant design,-and no .>.ew operating or failure modes.are created.

The scope of these TS changes is strictly limited to removal f of extraneous rei!rences to automatic Reactor Recirculation System flow control, which is no longer available. There are no new or different surveillance tests or actions required by the revisions. No TS requirements associated.

with operation in the manual flow control mode are affected, and there is no change in the degree of-protection currently af forded by existing surveillances. There is also no addition, deletion, or modification of any Class IE component or circuit involved.

Therefore, the proposed charigo does not create the possibility of a new or different kind of accident from those previously analyzed.

c. The change would not involve a significant reduction in the margin of safoty.

s Both hoop Manual and Non-Loop Hanual modes of flow control have been separately evaluated and approved. No assumptions, methods, or results of applicable safety analyses are changed. The proposed changes do not alter the margin of safety currently realized by implementation of the existing TS for operation in the Loop Manual mode of flow control. Since cperation in-automatic flow control is no-longer possible, there are no margins of safety related to this mode of operation which must be implemented by the TS.

Removal of references to the Non-Loop Manual mode only makes the TS consistent with plant design and avoids potential confusion.

These changes thus do_not involve a significant reduction in the margin of safety.

4. Based on the above evaluation, Entergy Operations has concluded that operation in accordance with the proposed amendment-Involves no significant hazards considerations.

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