ML20005H112

Application for Amend to License DPR-57,replacing Existing Trip Unit Circuit Boards in Alternate Rod Injection Sys W/ Circuit Boards Mfg by Different Mfg

ML20005H112
Person / Time
Site:	Hatch
Issue date:	01/15/1990
From:	Hairston W GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20005H113	List: ML20005H112 ML20005H118
References
HL-839, NUDOCS 9001240156
Download: ML20005H112 (9)

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WCleN ffet@ s HL-839 January 15, 1990:

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V. S Nuclear Regulatory Commission-W:n .  : Attention: Document-Control. Desk

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on PLANT HATCH - UNIT 1 q NRC DOCKET 50-321 .

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. OPERATING. LICENSES DRP-57 I ;, '

' REQUEST TO REVISE TECHNICAL SPECIFICATIONS:

CHANGES'T0'ATWS-RPT SPECIFICATION j

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3 Gentlemen:

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Lin accordance with the provisions offl0 CFR 50.90, as required by. 1

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"A 10CFR 50.59(C) (1), Georgia Power Company (GPC) he'reby proposes changes to the Plant Hatch Unit l Technical Specifications, Appendix A to Operating

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u The. Technical Specifications for Plant Hatch Unit 1 currently provide 't requirements' for the Anticipated Transients Without Scram - Recirculation .

. Pump Trip (ATWS-RPT) . On December 14, 1988, the NRC issued to Georgia  !

Power Company. the, results of'its review of this system with regard to the i WWS ' rul e, : .10CFR . 50.62. In this letter, the NRC required upgrades of the  ::

< - PlantLHatch design by replacing the existing trip unit circuit boards in  ;

the Alternate Rod Insertion (ARI) system with circuit boards manufactured i l 4

by a different manufacturer, to modify RPT actuation to a different logic, {

andLto provide testability of'the ARI system while at power. This letter i also: indicated'GPC's commitment to complete these changes in the Unit 1  ;

c- 1990' outage. t

i In order to implement these changes on Unit 1, the specifications  !

Ldealing with the ATWS-RPT. system require revision. Therefore, GPC proposes ENo that the Technical Specifications be revised to provide for the upgraded

,O design'.. Since the Plant- Hatch Unit 1 outage may end as early as mid-May 6

@Q' o ~ n1990, GPC requests that this amendment be approved and' issued by the NRC no Llatar than that date. Similar plant modifications are planned for the next 1

O Unit 2 outage, currently scheduled for the Spring of 1991. GPC will 7@88 M request a Unit 2- Technical Specifications change in a time frame

commensurate with implementation of the Unit 2 modificaticns, 1"O

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ite d, Enclosure 1 provides the detailed descriptions of the proposed changes coce and the circumstances necessitating the change request. d.

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• U.1S-lN'uclear Regulatory Commission qh, R nuhry.15, 1990 ,

4- Page 2-N Enclosure' 2 details the bases for. our determination that-the proposed

p. 1 changes do not involve significant hazards considerations.

r Enclosure 3~provides page change instructions for incorporating the-proposedichanges into the Technical specifications. The proposed changed pages for Unit 1 follow. Enclosure 3.

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. To allow time for procedure revisions and orderly incorporation into copies-of the Technical . Specifications, GPC requests the proposed amendment, once approved.by the NRC, be issued with an effective date to be no.later than 60 days from the date of issuance of the amendment.

-In- accordance >to the requirements of 10CFR 50.91, a copy of this letter and all applicable-enclosures will be sent to Mr. J. L. Ledbetter of I the Environmental Protection Division of the Georgia Department of Natural l Resources.

Mr. W. G.'Hairston, III states he is Senior Vice President of Georgia Power Company and is authorized to execute this oath on. behalf of Georgia li Power Compa'ny and to.the best of his knowledge and belief, the. facts set forth in this letter are true. ]

GEORGIA POWER COMPANY j l

l BY: /M C W. G. Hairston, III-SworntoandsubscribedbeforemethisJ5$dayof Go uomu , 1990. .

A N~ota bI Public MY COMM4 ON EXPlREG DEC.15,1992 WGH,'l ll :CRP/kdc

Enclosures:

1. Basis for Change Request.

2. 10 CFR 50.92 Evaluation.

3. Page Change Instructions.

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' V; S.- Nuclear Regulatory Commission J2nu.ry 15, 1990.

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. c: Georaia Power Comnany Mr. H. C. Nix,- Jr. , General Manager. - Hatch Mr. J. D.- Heidt, Manager, Licensing and Engineering - Hatch GO-NORMS U.' S. Nuclear Reaulatory Commission. Washinaton. D.C.

Mr. L. P. Crocker, Licensing Project Manager.- Hatch-

'4 U. S. Nuclear Reaulatory Commission. Reaion 11

' Mr. S. B. Ebneter, Regional Administrator Mr. J. E. Menning, Senior Resident Inspector - Hatch State of Georcia +

Mr. J. L. Ledbetter, Commissioner - Department of Natural Resources t

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m 4, ENCLOSURE l-PLANT HATCH - UNIT 1 l 4 '

NRC DOCKET 50-321  ;

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. OPERATING LICENSE DRP CHANGES-TO ATWS-RPT SPECIFICATION p

. BASIS FOR CHANGE RE0 VEST PROPOSED CHANGE l':

Certain proposed changes to the Unit 1 Technical Specifications in Table 3.2-9 are necessary due to the modifications being made to. achieve. .

consistency with the ATWS rule 10CFR50.62. In Table 3.2-9, the required 1 operable channels per trip system are being changed from "1" to "2" and

. notes.are being added or modified to provide for a "two-out-of-two" logic L

scheme. In this scheme, either of the two ATWS-RPT trip systems can trip both recirculation pumps. Each ATWS-RPT system will trip if "2-out-of-2"

, reactor water level 2 signals or "2-out-of-2" reactor high pressure signals.

are received, t-'

In addition, consistent with the "two-out-of-two" logic scheme, provisions have been made for continued plant operation with an inoperable channel placed in its trip condition.

Basis for Proposed Chanae 1:

The current Plant Hatch, Unit 1 ATWS-RPT initiation logic design uses' a <

"one-out w f-two" logic scheme. The trip signal is. initiated by either one t of two reactor vessel low water level or one of two reactor vessel high pressure signals. -The NRC staff, in their letter to GPC of December 14, 1988, determined that a different logic would be more consistent with the ATWS Rule guidelines in minimizing inadvertent actuations. Georgia Power Company selected a "two-out-of-two" logic design. Accordingly, these changes are being made within Table 3.2-9 of the Unit 1 Technical Specif'7ations to provide for a "two-out-of-two" logic scheme.

The. provision to place an inoperable channel in its tripped condition and allow continued plant operation is consistent with the current BWR Standard Technical' Specifications for a "two-out-of-two" logic system. Single failure ~ protection of the plant logic system is maintained while the channel is in the tripped condition.

The provision which allows up to fourteen days operation with an inoperable trip system is being maintained. This LCO time is consistent with the

current Plant Hatch Unit 2 Technical Specifications and is similar to the BWR Standard Technical Specifications.

PROPOSED CHANGE 2:

Certain proposed changes to the Unit 1 Technical Specifications are being made in order to be consistent with the current BWR Standard Technical Specifications, and the philosophy of Analog Transmitter Trip System (ATTS) design as previously approved by the NRC.

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I ENCLOSURE'lt(continued)

,- REQUEST TO REVISE TECHNICAL SPECIFICATIONS:  :

CHANGES TO'ATWS-RPT SPECIFICATION BASIS'FOR CHANGE RE0 VEST _ j In Table 3.2-9, the " trip settings" are being chanaed to be consistent with the-instrument's allowable values; the analytical limit for the RPT Water Level 2 trip setting has been lowered to be consistent with the other Reactor Water Level 2 trip settings; and an editorial change has been made to identify the reactor vessel water level trip as a " Level 2" trip.

In Table 4.2-9, it is~ proposed that the surveillance frequencies for. the ATWS-RPT reactor vessel. water level and reactor pressure instrument be changed to "once per shift".for the instrument check minimum frequency and "once per month" for the instrument functional test minimum frequency.

Basis for Proposed Chanae 2:

'The trip settings for the ATWS-RPT currently in the Unit 1 Technical Specifications are analytical limits for the reactor vessel low water level and the reactor vessel high pressure instrument functions. These. trip i settings are proposed to be changed from analytical limits to allowable '

values based on the setpoint calculation methodology approved by the NRC

-for ATTS in/ Amendment 103 to the Unit 1 Technical Specifications. This methodology calculated allowable values of 1095 psig for the high pressure

~ and -47 in. fi20 for the low water level ATWS-RPT trip settings based on

'" analytical limits of; 1120 psig and -58 in. H2O respectively. The analytical limit for the reactor vessel low water level trip is therefore proposed to be lowered from the current analytical limit of -38 in. H2O to

-58 in. H20. This creates a consistent analytical limit and trip setting for. all the Reactor Vessel Level 2_ trip functions.

Lowering the analytical limit for the reactor low water level trip setting ,

from -38'in. H20 to -58 in. H2O is acceptable since the transient and accident analysis in the plant FSAR will be insignificant 1y affected. This i is because the safety function of the RPT is to mitigate the consequences of anticipated transient without scram (ATWS) events. However, for most ATWS scenerios, the RPT on Level 2 is a secondary signal to the RPT on high reactor' pressure. The only exception is the ATWS event of loss of feedwater flow. The-loss of feedwater flow is a mild ATWS event since the fuel would not experience boiling transition and the suppression pool pressure and temperature are unchanged. The change of the RPT analytical limit from -38 in, to -58 in, will'not affect these results because the fuel will still be sufficiently covered and the reactor will not be isolated (MSIV isolation is at Level 1). Therefore, the analytical limit of -58 in, for the RPT is acceptable for Plant Hatch Unit 1.

Based on analytical limits of 1120 psig and -58 in. H2 O for the reactor high pressure and reactor vessel low water level functions respectively, the trip settings in the Unit 1 Technical Specifications of 1095 psig and

-47 in. H 02 are calculated using NRC accepted methodology. Therefore, these trip settings are conservative with respect to their analytical limits.

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,' ENCLOSURE:1;(continued)-

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.,. REQUEST 10 REVISE TECHNICAL SPECIFICATIONS:

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L CHANGES TO ATWS-RPT' SPECIFICATION DASIS FOR CHANGE RE0 VEST

The editorial remark of' adding " Level 2" to the trip condition nomenclature.

for-the reactor vessel water level instrument is purely editorial in nature, is more descriptive, and does not indicate a modification to plant design.

The changes to Table 4.229 will result in more frequent instrumentation checks and-. functional testing than is presently specified in the Unit 1

. Technical Specifications, and would therefore provide equal or better

assurance of system availability.

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- ' ENCLOSURE 2

-C s .

PLANT HATCH ' UNIT 1

.NRC DOCKET 50-321

.- , OPERATING LICENSE DRP-57 c . CHANGES TO ATWS RPT SPECIFICATION 3 10CFR 50.92 EVALUATIONS PROPOSED CHANGE 1:

As discussed in the' basis for change request, certain proposed changes to

the Unit'l Technical Specifications in Table 3.2-9 are necessary due to the ,

' modifications being.made to achieve consistency with the ATWS Rule 10CFR i 50.62. . In Table 3.2-9, the required operable channels per trip system are i being changed from "1" to "2" and notes are being added or modified to provide for a "two_out-of-two" logic scheme, in this scheme, either of the two ATWS RPT-trip systems can trip both recirculation pumps. Each ATWS-RPT

- system will' trip if "2-out-of-2" reactor water level 2 signals or "2-out-of-2" reactor high pressure signals are received.

I In addition, consistent with the "two-out-of-two" logic scheme, provisions' have been made for continued plant operation with an inoperable channel placed in its trip condition.

Basis for Proposed Chanae 1:

See Enclosure 1 for a description of the safety basis for the proposed change.

This change does not involve a significant increase in the probability or

-consequences of an accident, because the "two-out-of-two" logic scheme is designed to reduce inadvertent actuations of the ATWS-RPT trip system.

Therefore, overall plant reliability is increased. This design meets the 10CFR50.62, paragraph (c)(5) requirement to automatically trip the reactor coolant recirculation pumps. The proposed changes do not change, degrade or prevent any. actions or assumptions in the current ATWS analyses.

'The possibility of a different kind of accident from any analyzed previously._is not- created by this change, since the proposed change is consistent with the ATWS Rule guidelines. The'ATWS-RPT logic is proposed

!' to be_ changed to "two-out-of-two" to minimize inadvertent actuations and to allow maintenance testing or calibration during power operation.

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[ Margins of safety are not significantly reduced by this change, since the provision to place an inoperable channel in the tripped condition and allow ,

1 continued plant operation is consistent with the current BWR Standard Technical Specifications for a "two-out-of-two" logic system. While in this "LC0" condition, single failure capability of the plant logic system is being maintained while the channel is in the tripped condition. If a a complete trip system is inoperable, the 14 day LC0 for continued plant operation will be maintained.

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. ENCLOSUREL2.(continued)

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1, f REQUESTLTO REVISE TECHNICAL SPECIFICATIONS: ,

CHANGES 10 ATWS-RPT SPECIFICATION 10CFR 50.92 EVALUATIONS PROPOSED C'HANGE'2:

~ As discussed in the basis for change request, certain proposed changes to

'the Unit- 1 Technical Specifications are being made to be consistent with s the current BWR Standard Technical Specifications, and the philosophy of

' NRC.

Analog Transmitter Trip-System (ATTS) design as previously approved by the

- ~ In Table 3.2-9, the trip settings are being changed to be consistent with the instrument's allowable value; the analytical limit for the RPT Water Level 2 limit;2 and-an trip' setting-has editorialbeen chanlowered to be consistent- with the other level

' vessel water level . trip-as a "ge has 2" Level been trip.made to identify the reactor-Lin Table'4.2-9, itLis proposed that the surveillance frequencies for the ATWS-RPT reactor vessel water level and reactor pressure instrument be

. changed to "onceLper shift"'for the instrument check minimum frequency and "once per month" for the instrument functional test minimum frequency.

Basis for Prooosed Chance 2:

See Enclosure

-change. l'for a description of the safety basis for.the proposed Thisl change does not' involve a significant increase in the probability or

. consequences of, an accident, since lowering the analytical limit for the reactor water low level trip from -38 in. H2 O to -58.in. H2O will not affect the-plant FSAR nor will plant safety be affected. A review of the tra.nsient and accident analysis in the plant FSAR shows that the RPT on low water level has insignificant effect on these analyses. This is because

' the afety. function of the RPT is to mitigate the consequences of anticipated transient without scram (ATWS) events. However, for most ATWS events, pressure.the RPT on Level 2 is a secondary signal to the RPT on high reactor The only exception is the ATWS event of loss of feedwater flow.

The. loss of feedwater flow is a mild ATWS event since the fuel would not experience boiling transition and the suppression pool pressure and

, temperature are unchanged. The change of the RPT setpoint analytical limit 2

fuel will still be 0sufficiently from -38 in. H to -58 in. 2covered H O will and not the affect thesewill reactor results not bebecause the isolated (MSIV isolation is at Level 1). Therefore, the analytical limit

- of -58 in.- H2 0 for the RPT is acceptable for Plant Hatch Unit 1.

to Table 4.2-9 will ' require more frequent instrumentation checks andChanges functional testing than is presently specified, is consistent with the NRC approved surveillances for the ATTS design in Unit 1 Technical Specificaiton Amendment 103, and would therefore provide equal or better assurance of system availability.

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ENCLOSURE 2 (continued)-

1 ,.-

REQUEST TO REVISE TECHNICAL SPECIFICATIONS:

CHANGES TO-ATWS-RPT SPECIFICATION ,

10CFR 50.92 EVALUATIONS The_ possibility of a different kind of accident from any analyzed

'previously is not created by this change, since the proposed change of using allowable-values. for the ATWS-RPT reactor value water level trip function, and the editorial change of identifying the reactor vessel water level _ trip; as Level 9" do not change any plant failure modes.

Margins of safety are not significantly reduced by this change, since lowering the analytical limit for the RPT water level trip setting does not have a significant affect on any plant accident analysis. The ATWS-RPT reactor vessel low water level and reactor high reactor pressure trip settings are calculated using the setpoint calculation methodology approved

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'by the NRC for the ATTS system in Amendment 103 to the Unit 1 Technical Specifications. - This methodology calculated allowable values of 1095 psig for the high pressure and -47 in. H2O for the Level 2 reactor vessel water level ATWS-RPT trip settings. The changes of -38 in. H2O to -47 in. H20 for reactor vessel low water. level and 1120 psig to 1095 psig for reactor high-pressure trip settings are therfore conservative since these changes 1 represent a move away from analytical limits and a move to the _use of allowable values in the Unit 1 Technical Specifications. Allowable values provide ~a conservative margin for a technical specifications value from the

> analytical limit.

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