ML20087P951
| ML20087P951 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 04/03/1984 |
| From: | Gucwa L GEORGIA POWER CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| NED-84-186, TAC-54433, TAC-54607, NUDOCS 8404100144 | |
| Download: ML20087P951 (5) | |
Text
o Georgia Power Company '
4 333 Pedmont Avenue Atlanta. Georgia 30308 Telephone 404 526f526 Mahng Address:
Post Ofhce Box 4545 A!!anta. Georgia 30302 Georgia Power L T. Gucwa
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Manager Nuclear Engineering NED-84-186 and chief Nuclear Engineer April 3, 1984 Director of Nuclear Reactor Regulation Attention: Mr. John F. Stolz, Chief Operating Reactors Branch No. 4 Division of Licensing U. S. Nuclear Regulatory Cannission Washington, D. C.
20555 NRC DOClerS 50-321, 50-366 OPERATING LICENSES DPR-57, NPF-5 EDWIN I. HATCH NUCLEAR PLANT UNITS 1, 2 xtwedT TO CHANGE TECHNICAL SPECIFICATIONS APIN/RIE/ TECH SPEC IMPROVEMENIS Gentlenen:
Our letter of February 6,1984, requested an APIN/RIN/IECH SPEC (AWS) technical specification anendment.
Enclosed are hardwaro descriptions and drawings which are suhr.itted' in support of the review of that amendment.
Specifically, enclosed are:
EDI No. RWHA Rev. O and 1 FDI No. RJKA Rev. O and 1 Also, revisions to pages 1 through 4 of Attachnent 2 of our February 6, 1984, subnittal are enclosed.
These-revised pages supersede the original
'pages 1 through 4 and more clearly define the reasons that ARTS changes will l
.not result in a significant hazards consideration.
GEORGIA POWER CCMPANY B404100144 E :'M
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PIAs L. T. Gucwa DLTAnb Enclosure
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J. T. Beckhan, Jr. (w/o drawings)
H. C. Nix, Jr. (w/o drawings)
Senior Resident Inspector (w/o drawings) i j J. P. O'Reilly (w/o drawings) _
J. L. Ledbetter (w/o drawings)
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GeorgiaPowerg AmcmmT 2 NRC DOCKETS 50-321, 50-366 e
OPERATING LICENSES DPR-57, NPF-5
- EDWIN I. HA'ICH NUCLEAR PIANT UNITS 1, 2 RiDuursr 'IO CHANGE TECHNICAL SPECIFICATIONS, APIN/RIN/PECH SPEC IMPROVEMENTS Pursuant to 10 CFR 50.92, the following statenents provide a stanary of and the basis for the proposed changes:
1.
Change the
' slope of-the-flow-biased Average Power Range
. Monitor / Simulated %ermal Power Monitor (APIN/ STIM) scram and rod block setpoints fra 0.66 to-0.58 and change their intercept values such that, at rated L core flow, the setpoints are unchanged from their current values.
. BASIS:
- %e Extended Ioad Line Limit Analyses (ELLIA), NEDC 30260, provide the analytical: bases.for raising the APBM scram and rod block lines at the bottom of the flow' control range by reducing the flow biasing slopes
~fra 0.66 to 0.58.
Analyses - have shown. that the consequences of. events initiated fra within the region of the Power-Flow operating map made accessible by this 1 changes, are bounded by the consequences of ' the same events
" initiated from the licensing basis condition.
Changing the slope of these lines has the potential to increase the power-flow ratio following a?two-pop trip event.
Standard core stability ' calculations were performed for. this scenario.
Se results meet the acceptance criteria
- defined by the NRC.
Adjusting the zero-drive-flow intercept values as indicated assures that the rated-flow setpoints maintain the margins existing under current analyses. %is proposed change therefore has no
~ dverse: effects on the probability -or. consequences of previously a
postulated accidents. - Because no physical: change is required - to operate.
in' the ELLIA region, the proposed change does not create the possibility L
-of a new, previously unanalyzed accident. As stated above, because the consequences of events-initiated within the m 1A region are bounded by the consequences of, the sane' events initiated -fr a licensing basis conditions, margins of safety are not reduced. Furthermore, the results of f this change are clearly within all acceptance criteria as presented
- in the licensing basis docment, GESTAR'II.
Conseguently, this change twill not' result in~a significant hazards consideration.
' 2'., :%e ARTS improvenents have been divided into two areas.of changes, those
. associated with the APIN/ STIM setdown and those associated with the Rod-
-Block ;. Monitor ' (RIM).. %e changes have been analyzed collectively and the results reported in NEDC-30474-P, " General Electric BWR ' Licensing
. Report:; Average. Power -Range Monitor, Rod Block Monitor and Technical l-l Specification Duprovement (ARTS)~ Program for Edwin I.
Hatch Nuclear L
Plant, Units 1 and.2."'
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page-2
' A description of and the basis for the proposed ARTS changes is given below.
A.-
Delete the requirenent for setdown of the APBM/STPM flow-biased scran and rod block setpoints, _ when core maximtsn fraction of limiting power d_ensity (MFLPD). exceeds the fraction of core rated Ibermal power.(core total peaking factor exceeding design peaking factor).
In order to maintain function and margins, replace the setdown requirenent with new multipliers to the MCPR and APIRGR
~
, operating limits when core power or flow conditions are less than the licensed conditions.
BASIS:
%e setdown requirenent originated frm the obsolete Hench-Levy Minimtzn Critical Heat Flux Ratio (MCHER) thermal limit criterion. %e change to GETAB/GEXL -with its de-emphasis of local thermal-hydraulic conditions makes the use of APW/STM trip setdown (based on core total peaking
- factor) much less meaningful for the purpose of assuring that onset of transient boiling does not occur.during anticipated. operational
-transients initiated fra power levels less than rated.
Further, the analysis :of limiting transient events with primary reliance on anticipatory scran trips - (e.g., turbine. control valve and stop valve position 'scran trips) and with reduced reliance on APFM fim-biased flux scrans has~ led to a more effective and operationally acceptable alternative 'to the setdown requirenent.
ARTS proposes that alternative.. ARTS uses results fra analyses of -limiting operational transients - and of the design. basis loss of l coolant accident to define thermal 1 operating Elimits. ~ %ese limits assure that the applicable fuel licensing criteria stated in GESTAR II
- (NEEE-24011-P-A-6 and NEDE-240ll-P-A-US-6) and in the E. I. Hatch Uhit 1 FSAR, Chapter 14, are satisfied without the setdown of the APW /STE flow biased scram and rod block trips.
Adninistration of fuel thermal limits is more direct and
. fewer manual setpaint adjustments are required.
As part of' the justification for renoval.of the-setdown requirenent, it is necessary to define the operating limit MCPR (OIMCPR) such that no postulated transient events initiated' fr m off-rated power or flow conditions may result in. violation of the MCPR Safety Limit. ' Analyses ofithe limiting. transients, presented in NEDC-30474-P, show ' that the ARrS. power-dependent multiplier, (k ),
when multiplied by the p
rated-power, rated-flow operating limit MCPR, conservatively bounds the operating 'MCPR ' needed ' to insure the MCPR safety. limit. is not. violated
~
- during any. anticipated transient.
Se flow-dependent MCPR requirenent introduced by ARTS, MCPRp, was _ derived fra results of analysis ' 'of slow-flow runout events and, - thus, serves the sane purpose as the Kf
' multipliers, which it. replaces.
No MCPRp is required for Autmatic
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-Attachment 2 page 3 1
Flow Control because that mode of operation will not be used.
%e governing MCPR limit for any power and flow condition is the greater of the values determined based on core power considerations (MCPF ) or p
core flow consideratons (MCPRy).
6 In. the absence of the APM scrm setdown requirenent, new limits are
. also substituted to assure ' cepliance with the fuel thermal-mechanical l
' design. base given in GESTAR II.
Power-dependent limits on linear heat generation rate were generated from the. sane transient calculations used
'to determine-the power dependent MCPR multiplier, Kp.
- Also,
' flow-dependent linear heat' generation rate requirenents were derived such that the peak transient during slow-flow runout transients will not
- increase' above -the GESTAR II design basis values.
For ease of a&ninistration, the ARTS linear heat generation ' rate limits are defined as multipliers, MAPFACp and - MAPFAC, which apply to the existing F
' fuel-type _ and exposure-dependent MAPIRGR limits.
%e flow-dependent MAPIRGR multiplier,
- MAPFACy, definiton also incorporates 'the requirenents derived fra the IOCA analysis performed under ARTS,
-without taking credit for the existing APBM/STM setdown based on core l
- total peaking - factor.
%e more limiting of the MAPIEGR multipliers at any time is used to calculate the governing MAPIRGR limit at that time.
^
-Analyses' -performed to _ support elimination of the APM setdown requirement were done with methods given__ in GESTAR II, which have been previously reviewed and approved.
The acceptance criteria used in ARTS for ' defining - the off-rated MCPR and APIRGR requirements were the sane criteria defined for fuel-rod integrity in the existing licensing basis 1
(GESTAR II). ' Sere is no reduction in the margin of safety, because all-acceptance criteria' are met under this change.
S e causes of each of the events evaluated in the Plant Safety Analysis chapters of _the Hatch FSARs were considered.
%e probability of occurrence of each of - the causes enumerated would be unaffected by
-operation of either reactor with fuel thermal limits defined as
' described above.
Marthermore, no.new modes that.could lead to occurrence of the FSAR events or.other events could be identified due to use of the. ARPS operating' limits.
Information presented : in. NEDC 30474-P shows_ that the consequences of -
. accidents and transient events which might'be affected by. implenentation
~
of this change -'are bounded by - the consequences of - the same ' events initiated.. fran - current licensing basis conditions, provided the
. appropriate ~ adjustments to the operating limits as ' outlined above are made.
%e proposed Technical Specification. changes will -' assure that needed adjustments are made.
'B.
Replace the-Rod Block Monitor - (RM) flow-biased trip equation with power-dependent setpoint definitions, incorporate RBM filter and time. delay setpoints,~ and change the REM downscale trip setpoint.
- Add -.' appropriate ' RM. operability and surveillance requirenents, including the definition ~ of Limiting Rod Pattern for Rod Withdrawal Error ;(BNE). '
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lGeorgiaPowerI Attachnent 2 page 4 BASIS:
' Revision of the RIM trip logic provides a syste response which more accurately reflects the actual margin to the MCPR safety limit at various power conditions.
An exhaustive, generic Rod Withdrawal Error
- (INE) analysis - was performed to evaluate the upgraded REM syste described in NEDC-30474-P.
It was shown that all requirements for prevention of cladding failure during an RWE are met, if the logic setpoints, filter setpoints, time delays, and downscale trips defined in this change and the power-dependent Minimta Critical Power' Ratio (MCPRp). operating limit adjustment, described in Its A above, are
~ implemented.
%e generic RWE analysis performed for ARTS was also used to determine the pre-RNE MCPR margin that would assure that the complete withdrawal
- of any single control rod would not violate the Safety Limits whenever
~ he operational' MCPR 'is. above the limiting values defined by this t
- change, i.e., the core -is not operating on a limiting rod pattern for RHE..
J-
' %e' ARTS analyses also justify cmplete bypass of the REM systs below 130%.of rated thermal power.
%is part of the mendment also would require a functional test of. the RIM prior to withdrawal of control rods when ' REN operability is required and when only one REM channel is operable.
For Hatch Unit 1, the Limiting Conditions for Operation with only one or
. neither REM channel operable are defined for use when' RIM operability is required.
Hatch Unit 2 Limiting Conditions for Operation are already defined for this condition.
Analyses performed to support the changes to the REM systs were done -
with methods given in GESTAR II, which have been previously reviewed and l
. approved.- he acceptance criteria used in the ARTS Progra for defining
~
the - power-biased REM. setpoints were the same criteria defined for fuel-rod integrity in the original licensing basis given in GESTAR II.
-%ere is no reduction in the margin of safety nor is there any increase L
in the consequence of a postulated RWE, because all acceptance criteria are met-under the new system.
Changes in the REM design and operating permeters will improve RBM reliability and enhance operator interface a
with the RIMY reducing the probability of a rod withdrawal error event due'to operator error, t:
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.%e REN pays no role in any nther. postuated transients. - No _new failure
' modes - that could create the possiblity of a new or different kind of accident are introduced by the proposed changes to RIN systes because no other plant systes are affected.
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