ML20136F725
| ML20136F725 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/06/1997 |
| From: | Abney T TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20136F731 | List: |
| References | |
| NUDOCS 9703170034 | |
| Download: ML20136F725 (54) | |
Text
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Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabama 35609-2000 March 6, 1997 TVA-BFN-TS-353R1 10 CFR 50.4 10 CFR 50.90 10 CFR 50.91 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
)
Docket Nos. 50-259 j
Tennessee Valley Authority
)
50-260 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) - UNITS 1, 2, AND 3 -
TECHNICAL SPECIFICATIONS (TS) CHANGE 353R1 - POWER RANGE NEUTRON MONITOR (PRNM) UPGRADE WITH IMPLEMENTATION OF AVERAGE POWER RANGE MONITOR (APRM) AND ROD BLOCK MONITOR (RBM) TS (ARTS) IMPROVEMENTS AND MAXIMUM EI"1NDED LOAD LINE LIMIT (MELLL) ANALYSES - REVISION 1 On June 2, 1995, TVA submitted amendment request TS-353 (Enclosure 1, Reference 1) to licenses DPR-33, DPR-52, and DPR-68 to revise the TS for Units 1, 2,
and 3 to include changes associated with implementation of the PRNM upgrade,
)
and to incorporate changes related to ARTS and MELLL Analyses.
The previous TS-353 submittal was based, in part, on Licensing Topical Report NEDC-32410P, Nuclear Measurement Analysis and Control Power Range Neutron Monitor (NUMAC PRNM)
Retrofit Plus Option III Stability Trip Functions, March 1995.
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U.S. Nuclear Regulatory Commission Page 2-March 6, 1997 NEDC-32410P was subsequently accepted for use in licensing applications as documented in an NRC Safety Evaluation Report (SER) dated' September 5, 1995.
This submittal is being provided to account for changes made to the Topical Report (issued as NEDC-32410P-A) during the review process and to address several plant specific items listed in the SER.
This submittal supersedes in entirety the June 2, 1995,.
version of TS-353.
These proposed TS include the necessary TS revisions for the planned replacement of the power range monitoring portion of the existing Neutron Monitoring System with the advanced digital PRNM upgrade.
Implementation of the PRNM system will allow TVA to proceed with implementation of the long-term stability solution designated as Option III in NEDO-31960 and NEDO-31960, Supplement 1, "BWR Owners' Group Long Term Stability _ Solution Licensing Methodology" relating to Generic Letter 94-02.
The PRNM upgrade will be installed first during the Fall'1997 Unit 2 refueling outage for operation during the following fuel cycle (10).
During cycle 10, all PRNM functions will be in service with the exception of the stability monitor trip functions of the Oscillation Power Range Monitor (OPRM) module of the PRNM which will be operated in the " indicate only" mode for one cycle, and be fully enabled for cycle 11 operation.
For Unit 3, the PRNM will be installed in late 1998 for operation in cycle 9, and the OPRM trips enabled for the following fuel cycle (10).
Prior to enabling the OPRM trip function, related TS changes will be submitted.
Additionally, these proposed TS changes are needed for TVA's planned implementation of the ARTS /MELLL improvements.
The purpose of the ARTS /MELLL changes is to enhance operating flexibility and efficiency by implementing RBM design improvements, incorporating APRM/RBM TS improvements,
U.S. Nuclear Regulatory Commission Page 3 March 6, 1997 and expanding the current allowable operating domain to the MELLL region of the power / flow map.
NEDC-32433P, Maximum Extended Load Line Limit and ARTS Improvement Program Analyses for Browns Ferry Nuclear Plant Unit 1, 2,
and 3, was provided in the previous TS-353 submittal, and continues to be the primary basis document for the ARTS /MELLL changes. to this letter provides the~ description and evaluation of the proposed change, the significant hazards and environmental impact considerations, and other supporting information.
A copy _of NEDC-32433P is enclosed as to Enclosure 1 for reference.
This engineering report contains information proprietary to General Electric i
(GE) Company, and GE requests that the document be withheld from public ' disclosure in accordance with 10 CFR 2.790 (a) (4).
An affidavit supporting this request is provided in accordance with 10 CFR 2.7S0 (b) (1). to includes a confirmation of plant-specific actions as required by the SER for NEDC-32410P.
) contains copies of the appropriate marked-up TS pages from Units 1, 2,
and 3 to show the proposed changes.
' forwards the revised TS pages for Units 1, 2,
and 3 which incorporate the proposed changes.
In Enclosure 4,_
commitments are provided to implement the PRNM/ ARTS /MELLL changes prior to the restart of Unit 1 and Unit 3 in cycle 9.
TVA has determined that there are no significant hazards considerations associated with the proposed changes and that the TS change qualifies for a categorical exclusion from environmental review pursuant to the provisions of 10 CFR 51. 22 (c) ( 9 ).
The BFN Plant Operations Review Committee and the BFN Nuclear Safety Review Board have reviewed this proposed TS change anc, determined that operation of BFN Units 1, 2,
and 3 in accordance with the proposed change will not endanger the health and safety of the public.
Additionally, in accordance with 10 CFR 5 0. 91 (b) (1), TVA is sending a copy of this letter and
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U.S. Nuclear Regulatory Commission l
Page 4 i,
March 6, 1997 4
enclosures to the Alabama State Department of Public Health.
l TVA requests that the revised TS be approved by j
August 19, 1997, (30 days prior to shutdown of Unit 2 for its next refueling outage).
TVA requests that the revised TS be made effective according to the following milestone schedules a
{
Unit 1 - Effective 30 days after issuance.
Unit 2 - Effective prior to the restart of Unit 2 in l
Cycle 10 Unit 3 - Effective prior to the restart of Unit 3 in Cycle 9 Unit 1 is currently in a non-operational status, and TVA has no specific installation schedule for Unit 1.
However, the j
subject modifications will be installed prior to the i
return of Unit 1 to service, hnd so approval of the Unit 1 TS j
changes is requested.
4 i
An additional submittal will be provided in the near future requesting analogous TS changes in Improved Standard
]
Technical Specifications (ISTS) format to maintain l
consistency with proposed TS-362 which is the previously i
submitted conversion package of the custom TS to ISTS format.
Since, however, the implementation schedule for ISTS may be later than the restart of Unit 2 this coming Fall, approval j
of the requested TS changes in custom format may be necessary i
E to support installation of the PRNM system hardware, l
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U.S. Nuclear Regulatory Commission Page 5 March 6, 1997 4
If you have any questions about this change, please contact me at (205) 729-2636.
i Sincerely, i
/
i b
T. E. Abney Manager of Li ensin and Industry Efai s Enclosures cc: see page 6 Subscribed and sworn to before me on this Ld h day ofM(hch 1997.
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J U.S. Nuclear Regulatory Commission Page 6
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March 6. 1997 l
Enclosures cc (Enclosures) :
Chairman
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Limestone County Commission 310 West Washington Street Athens, Alabama 35611
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Mr. Mail S. Lesser, Branch Chief U.S. Nuclear Regulatory Commission F
-Region II 101 Marietta Street, NW, Suite 2900 i~
Atlanta, Georgia 30323 3
NRC Resident Inspector Browns Ferry Nuclear Plant i
10833 Shaw Road 3
Athens, Alabama 35611 y
j Mr. Joseph F. Williams, Project Manager U.S. Nuclear Regulatory Commission i
One White Flint, North
}
11555 Rockville Pike i
Rockville, Maryland 20852
]
Dr. Donald E. Williamson l'
. State Health Officer 1
Alabama State Department of Public Health c
434 Monroe Street j
Montgomery, Alabama 36130-3017 i
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__..___._...__.m.-..._.-._
HNCLOSURE 4 TENNESSEE VALLEY AUTHORITY-UNITS 1 AND 3 TS-353R1 PRNM/ ARTS /MELLL l
COMMITMENT
SUMMARY
1.
Prior to the restart of Unit 1, TVA will implement the PRNM/ ARTS /MELLL changes described in TS-353R1.
2.
Prior to the. restart of Unit 3 in Cycle 9, TVA will implement the PRNM/ ARTS /MELLL changes described in TS-353R1.
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l ATTACHMENT 1 i
1 i
Maxhnum Extended Load Line Ilmit and ARTS Improvement Program Analyses for Browns Ferry Nuclear Plant Unit 1,2 and 3, NEDC-32433P 3
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4
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t 1-1
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i ENCLOSURE 1 l
ATTACHMENT 1 l
Maximum Extended Load Line Limit and ARTS Improvement Program Analyses for Browns Ferry Nuclear Plant Unit 1,2 and 3, NEDC-32433P i
i The above Attachment of this Package Contains Proprietary Information 1
ENCLOSURE 1 TENNESSEE VALLEY AUTHORITY l
BROWNS FERRY NUCLEAR PLANT (BFN)
UNITS 1, 2, and 3 PROPOSED TECHNICAL SPECIFICATIONS (TS) CHANGE TS-353R1 DESCRIPTION AND EVALUATION OF THE PROPOSED CHANGE INDEX I.
DESCRIPTION OF THE PROPOSED CHANGE El-2 II.
REASON FOR THE PROPOSED CHANGE El-25 III.
SAFETY ANALYSIS El-34 IV.
NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION El-41 V.
ENVIRONMENTAL IMPACT CONSIDERATION El-44 VI.
REFERENCES El-45 VII. ATTACHMENTS I GE Report, Maximum Extended Load Line Limit and ARTS Improvement Program Analyses for Browns Ferry Nuclear Plant Units 1, 2 and 3, NEDC-32433P.
Plant Specific Information Required for NUMAC PRNM Retrofit J
I.
DESCRIPTION OF THE PROPOSED CHANGE This proposed change to BFN TS consists, broadly, of two groups of changes, Group A and Group B.
The changes related to Group A are discussed below followed by the description of Group B changes.
Group A-The following proposed changes support the replacement of the power range portion of the existing Neutron Monitoring System (NMS) with a General Electric (GE) digital Nuclear Measurement Analysis and Control Power Range Neutron Monitor (NUMAC PRNM) retrofit design.
As part of the planned modification, the number of Average Power Range Monitor (APRM) instrument channels will be reduced from six to four.
The Local Power Range Monitor (LPRM) inputs to the APRMs will also be reconfigured.
The four APRM instrument channels will be combined in four 2-out-of-4 trip logic channels which provide input to the Reactor Protection System (RPS) trip channels.
The number of recirculation flow instrument channels associated with the APRMs will be increased from two total flow channels (four transmitters) to four total flow channels (eight j
transmitters).
BFN TS changes proposed in support of the planned Group A modifications are provided below. These changes are consistent with the TS changes recommended in Section 8 of Reference 2 for implementation of the NUMAC PRNM retrofit.
i TS page numbers are presented in the format "Page x.z/y.z-U1/U2/U3" where U1, U2, and U3 are the respective Unit 1, Unit 2, and Unit 3 page' numbers.
Where only one number is given, the TS page number is the same for all three units.
El-2
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- =.. -
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1.
Page 3.1/4.1-3/3/2.
For the APRMs, Table 3.1.A currently reads:
Min. No. of Operable Instr.
Channels For Trip Trip Level Shut.
Startup/
svetam ft)(211 Tri n Functinn sateina down narum) f7)
Hot Meandhv g
Action (1) l APRM (14) (24)
(25) l l
2 High Flux See Spec.
X
- 1. A or 1.8 j
(Flow Biased) 2.1.A.1 2
High Flux s 120%
X 1.A or 1.B (Fixed Trip) 2 High Flux 515% rated X(21)
X(17)
(15) 1.A j
power 2
Inoperative (13)
X (21)
X(17)
X 1.A 2
Downscale 23 (11)
(11)
X(12) 1.A or 1.B Indicated on Scale The proposed change revises the minimum operability requirements and actions, deletes the APRM Downscale trip function, deletes requirements for APRM trip functions in the Refuel mode, adds a 2-out-of-4 voter trip function, and adjusts associated notes.
The revised table is provided below.
Min. No. of Operable.
Instr.
Channels For Trip Trip I.evel Shut.
Startup/
Svaten (1)f231 Tr4 n Funteinn aateina h
Refuel f71 Mot eennAhv h
lee i nn (1)
APRM (16) (24)
(25) 3 (11)
High Flux See Spec.
X 1.A, 1.B.
(Flow Biased) 2.1.A.1 or 1.E 3 (11)
High Flux A 120%
X 1.A, 1.B.
(Fixed Trip) or 1.E 3 (11)
High Flux s15% rated (21)
X(1?)
(15)
- 1. A or 1.E power 3 (11)
Inoperative (13)
(21)
X (11)
X
- 1. A or 1.E 2
2-Out-of-4 (12)
(21)
X X
1.A or 1.F Voter El-3
2.
Page 3.1/4.1-5/5/4.
The proposed change adds the following actions to Note 1 of " Notes for Table 3.1.A":
E.
For the APRM trip functions, if one required APRM channel is inoperable, restore it to OPERABLE status or place the channel in trip within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
- f two or more required APRM channels are inoperab'e for one or more trip functions, restore t rip capability within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or initiate alternate: action listed in the table.
F.
For the APRM trip functions, if one required voter channel is inoperable, restore the channel to OPERABLE status, place the channel in trip, or place the associated trip system in trip within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
If one required voter channel is inoperable in both trip systems, restore one channel to OPERABLE status, place one channel in trip, or place one trip system in trip within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, or initiace alternate action listed in the table.
If two required voter channels are inoperable in one trip system, restore trip capability within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or initiate alternate action listed in the table.
3.
Page 3.1/4.1-5/5/4 Note 5 in " Notes for Table 3.1.A for Intermediate Range Monitors (IRMs) currently reads:
5.
IRMs are bypassed when APRMs are onscale and the reactor mode switch is in the RUN position.
The proposed. change revises Note 5 to read:
5.
IRMs are bypassed when the reactor mode switch is in the RUN position.
4.
Page 3.1/4. :L-6/6/5.
In Note 7 of " Notes for Table 3.1.A",
the proposed change deletes Note 7.E ("APRM 15 percent scram").
This reflects deletion of the requirement for the APRM scram function in the Refuel mode.
El-4
Notes 11, 12, and 13 in " Notes for Table 3.1.Aa currently read:
d
- 11. The APRM downscale trip function is only active when the reactor mode switch is in RUN.
- 12. The APRM downscale trip function is automatically bypassed when the IRM instrumentation is OPERABLE and not high.
The proposed change revises Notes 11, 12 and 13 to read:
- 11. Each APRM channel provides input to both trip systems.
- 12. Any combination of APRM upscale or inoperative trips from two or more non-bypassed APRM trip functions will trip all of the 2-out-of-4 voter trip functions.
- 13. Less than the required minimum number of OPERABLE LPRMs will cause an instrument channel inoperative alarm.
5.
Page 3.1/4.1-3/3/2 and Page 3.1/4.1-6/6/5.
In Table 3.1.A, the proposed change adds application of Note 21 to IRM High Flux in the Refuel mode, and revises Note 21 in " Notes for Table 3.1.A" as specified below.
Note 21, which currently provides an indirect requirement for enabling the Source Range Monitor (SRM) nor. coincidence High Flux scram, reads as follows:
(21)
Only required with any control rod withdrawn from a core cell containing one or more fuel assemblies.
The APRM High Flux and Inoperative Trips do not have to be OPERABLE in the REFUEL Mode if the Source Range Monitors are connected to give a noncoincidence, High Flux scram at El-5
I 4
d i
d 5 x 105 cps.
The SRMs shall be OPERABLE per Specification.3.10.B.1.
The removal of l
eight (8) shorting links is required to provide noncoincidence high flux scram protection from
~
the Source Range Monitors.
]
i.
The proposed change revises Note 21 to be a direct requirement for shorting link removal.
The revised j
Note 21 reads:
(21)
In the REFUEL Mode unless adequate shutdown margin has been demonstrated per Specification i
4.3.A.1 and the one-rod-out control rod block is l
OPERABLE per Specification 3.10.A.1,-whenever l
any control rod is withdrawn from a core cell
.containing one or more fuel assemblies either (a) shorting links shall be removed from--the.RPS circuitry to' enable the Source Range Monitor (SRM) noncoincidence high-flux scram function or j
(b) the indicated APRM trip functions shall be 8
OPERABLE per the requirements applicable in the STARTUP/ HOT. STANDBY Mode.
If the SRM noncoincidence high flux scram function is L
enabled, the SRMs shall be OPERABLE per l-Specification 3.10.B.1.
The removal'of eight
[
(8) shorting links is required'to provide
[
noncoincidence high-flux-scram protection from-i the SRMs.
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6.
Page 3.1/4.1-8/8/7.
In Table 4.1.A the Surveillance Requirements (SRs) for.APRMs currently read as follows:
5 aroun fni runce4anat Tame ne i a 4 -um p r-u -a.-v i1)
I.
3 APRM High Flux (15% seren)
C Trip output Relays (4) once/ Week (9)
- High Flux (Flow Biased)
B Trip Output Relays (4)
Once/ Week I
High Flux (Fixed Trip)
B Trip output Relaya (4) once/ Week Inoperative B
Trip Output Relays (4) once/ Week
~Downseale B
Trip output Relays (4)
Once/ Week Flow Bias B
(s)
(s) 4 h
El-6
The proposed change deletes the APRM functional testing " group" assignments, deletes requirements for the APRM Downscale and Flow Bias trip functions, revises the minimum functional test frequency for the APRM trip functions, adds testing requirements for the 2-out-of-4 voter trip function, specifies a 1
weekly test of the scram contactors initiated from the 2-out-of-4 voters, and adjusts associated notes.
The revised table is provided below:
Croun (2)
Punc*innal Test Minimum Premianc v (1)
J i
Trip output Relays (4) (S)
Every 6 months (9)
High Flux (Flow Biased)
Trip output Relays (4) (4)
Every 6 months High Plux (Fixed Trip)
Trip Output Relays (4) (5)
Every 6 months Inoperative Trip output Relayr (4) (5)
Every 6 monthe 2-Out-of-4 Voter Trip output Relays (4)
(5)
Every 6 monthe 2-Out-of.4 voter logic (10)
Each Refueling Outage Trip Scram Ce s vtors (11)
Once/ Week 7.
Page 3.1/4.1-10/10/9.
In " Notes for Table 4.1.A" the proposed change replaces Note 5 and Note 6 and adds new Notes 10 and 11.
Notes 5 and 6 currently read as follows:
5.
(Deleted) 6.
The functional test of the flow bias network is performed in accordance with Table 4.2.C.
The proposed change reads as follows:
5.
The channel functional test shall include both the APRM channels and the 2-out-of-4 voter channels.
6.
The channel functional test shall include both the APRM channels and the 2-out-of-4 voter channels plus the flow input function, excluding the flow transmitters.
El-7
- 10. Functional test consists of simulating APRM trip conditions at the 2-out-of-4 voter channel' inputs to check all combinations of two tripped inputs to the 2-out-of-4 voter logic in the voter channels.
- 11. Functional test consists of manually tripping the
]
2-out-of-4 voter trip outputs, one voter channel at a time, to demonstrate that each scram contactor for each RPS trip system channel (A1, A2, B1, and B2)' operates and produces a half-scram.
8.
Page 3.1/4.1-11/11/10.
In Table 4.1.B, the proposed change deletes group designations for APRM High Flux
" Output Signal", " Flow Bias Signal" and "LPRM Signal".
The proposed change also-indents "LPRM Signal" parallel with " Output Signal" and " Flow Bias Signal".
9.
Page 3.1/4.1-12/12/11.
Note 7 currently reads:
The Flow Bias Signal calibration will consist of calibrating the sensors, flow converters, and signal offset networks during each operating cycle.
The instrumentation is an analog type with redundant flow signals that can be compared.
The flow comparator trip and upscale will be functionally tested according to Table 4.2.C to ensure the proper operation during the operating cycle.
Refer to 4.1 Bases for further explanation of calibrating frequency.
The proposed change revises Note 7 to read:
The flow bias signal calibration will consist of calibrating the analog differential pressure flow sensors once per operating cycle.
Calibration of the flow bias processing system is done once per operating cycle as part of the overall APRM instrumentation calibration.
El-8 1
10.
Page 3/1/4.1-14/14/13.
The proposed change deletes the last sentence of the sixth paragraph which reads:
Three APRM instrument channels are provided for each protection trip system.
Following deletion, the proposed change adds:
The APRM system is divided into four APRM channels and four 2-out-of-4 trip voter channels.
Each APRM channel provides input to each of the four voter channels.
The four voter channels are divided into two groups of two each with each group of two providing input to one RPS trip system.
The APRM system is designed to allow one APRM channel, but no voter channels, to be bypassed.
A trip from any one unbypassed APRM will result in a " half-trip" in all four of the voter units, but no trip inputs to either RPS trip system.
A trip from any two unbypassed APRM channels will result in a full trip in each of the four voter channels, which in turn results in two trip inputs into each RPS trip system resulting in a full scram.
Each APRM instrument channel receives input signals from forty-three (43) Local Power Range Monitors (LPRMs).
A minimum of twenty (20) LPRM inputs with three (3) per axial level is required for the APRM instrument channel to be OPERABLE.
Fewer than the required minimum number of LPRM inputs generates an instrument channel inoperative alarm and a control rod block but does not result in an automatic trip input to the 2-out-of-4 voters.
11.
Page 3.1/4.1-15/15/14.
The proposed change revises the first two sentences of the first paragraph on this page, and deletes the third sentence of the paragraph.
The paragraph currently reads:
Each protection trip system has one more APRM than is necessary to meet the minimum number required per channel.
This allows the bypassing of one APRM per protection trip system for maintenance, testing or El-9 n
calibration.
Additional IRM channels have also been provided to allow for bypassing one such channel.
The bases for....
The revised paragraph will read:
Each protection trip system has one more IRM than is necessary to meet the minimum number required per channel.
This allows the bypassing of one IRM per protection trip system for maintenance, testing or calibration.
The bases for....
12.
Page 3.1/4.1-16/16/15.
The proposed change revises the sentence (approximately middle of the page) describing the APRM downscale function which currently reads:
Because of the APRM downscale limit of 2 3 percent when in the RUN mode and high level limit of s 15 percent when in the STARTUP Mode, the transition between the STARTUP and RUN Modes must be made with the APRM instrumentation indicating between 3 percent and 15 percent of rated power or a control rod scram will occur.
The proposed change revises the sentence to read:
Because of the APRM downscale rod block limit of 2 3 percent when in the RUN mode and high level flux scram limit of s 15 percent when in the STARTUP Mode, the transition between the STARTUP and RUN Modes must be made with the APRM instrumentation indicating between 3 percent and 15 percent of rated power.
13.
Page 3.1/4.1-17/17/16.
A sentence currently reads:
The channels listed in Tables 4.1.A and 4.1.B are divided into three groups for functional testing.
The proposed change revises this sentence to read:
Except for the APRMs which take credit for self-test capability, the channels listed in Tables 4.1.A and 4.1.B are divided into three groups for functional testing.
El-10
14.
Page 3.1/4.1-19/19,20/18,19.
The proposed change deletes the paragraph describing calibration of the APRM Flow Biasing Network which currently reads:
The frequency of calibration of the APRM Flow Biasing Network has been established at each refueling outage.
There are several instruments which must be calibrated and it will take several hours to perform the calibration of the entire network.
While the calibration is being performed, a zero flow signal will be sent to half of the APRMs resulting in a half scram and rod block condition.
Thus, if the calibration were performed during operation, flux shaping would not be possible.
Based on experience at other generating stations, drift of instruments, such as those in the Flow Biasing Network, is not significant and therefore, to avoid spurious scrams, a calibration frequency of each refueling outage is established.
The proposed change adds the following paragraphs describing the APRM self-test functions and periodic manual test requirements before the paragraph beginning "The sensitivity of LPRM detectors...":
The APRM and 2-out-of-4 voter channel hardware are provided with a self-test capability which automatically checks most of the critical hardware at least once per 15 minute interval whenever the APRM channel is in the operate mode.
This provides a virtually continuous monitoring of the essential APRM trip functions.
In the event a critical fault is detected, an " inoperative" trip signal results.
A fault detected in non-critical hardware results in an " inoperative" alarm.
Following receipt of an
" inoperative" trip or alarm signal, the operator can employ numerous diagnostic testing options to locate the problem.
The automatic self-test function is supplemented with a manual APRM trip functional test, including the 2-out-of-4 voter channels and the interface with the RPS trip systems.
In combination with the virtually continuous self-testing, the manual APRM trip El-11
functional test provides adequate functional testing of the APRM trip function.
Therefore, the six-month test frequency for the manual testing provides an acceptable level of availability of the APRM.
In addition to the above tests, the 2-out-of-4 voter is used to test the RPS scram contactors.
The output of each voter channel is tripped to produce a scram signal into each of the RPS trip system channels (A1, A2, B1, and B2) to individually operate the respective scram contactors.
The weekly test interval provides an acceptable level of availability of the scram contactors.
Each APRM teceives the output signals from two analog differential pressure flow transducers, one associated with recirculation loop A and the other with recirculation loop B.
These differential pressure signals are converted into representative digital loop flow signals within the same hardware that performs the APRM functions and are added to determine a total recirculation flow.
The total recirculation flow value is used by the APRM to determine the flow biased setpoints.
Each total recirculation flow signal developed by an APRM is compared in the hardware that performs the RBM functions to the signals from the remaining three APRMs.
An alarm is given if a preset compare level setpoint is exceeded.
The flow processing is integrated with the APRM processing and is covered by the same self-test and alarm functions described earlier.
As a result of the virtually continuous monitoring of the equipment performing the flow processing and the automatic comparison of redundant flow signals, it is acceptable to calibrate this equipment once per operating cycle.
15.
Page 3.2/4.2-25/25/24.
In Table 3.2.C, for the APRM rod block functions the proposed change revises the Minimum Operable Channels Per Trip Function from "4"
to "3" and deletes requiremente for the " Flow Bias Comparator" and " Flow Bias Upscale" rod block functions.
El-12
-- -.....=
=
- l Additional proposed changes in Table 3.2.C are described under the second group of changes, Group B.
16.
Page 3.2/4.2-26,27/26,27/25,26.
In " Notes for Table 3.2.C" the proposed change revises Note 5, Note 10.b, and Note 10.c as described below.
I Note 5 currently reads:
5.
During repair...not more than one SRM or RBM channel nor more than two APRM or IRM channels may be bypassed....
1 i
The proposed change revises Note 5 to read:
5.
During repair...not more than one SRM, RBM, or i
APRM channel nor more than two IRM channels may be bypassed....
4 Note 10.b, APRM inoperative trips (1), (2), and (3) currently read:
4 4
(1) Local " operate-calibrate" switch not in operate.
(2) Less than 14 LPRM inputs.
I (3) Circuit boards not in circuit.
The proposed change revises these notes and adds Note 10.b (4).
The proposed change reads as follows:
(1) Local APRM chassis mode switch not in operate.
(2) Less than the required minimum number of LPRM inputs, both total and per axial level.
(3) APRM module unplugged.
(4) Self-test detected critical fault.
1 Note 10.c, Rod Block Monitor (RBM) inoperative trip (1) and (2) currently reads:
(1) Local " operate-calibrate" switch not in operate.
3 El-13
i l
(2) Circuit boards not in circuit.
The proposed change revises this note and adds Note 10. c. ( 5 ).
The proposed change reads as follows:
i (1) Local RBM chassis mode switch not in operate.
1 (2) RBM module unplugged.
(5) Self-test detected critical fault.
Additional proposed changes in Notes for Table 3.2.C are described under the second group of changes, Group B.
17.
Page 3.2/4.2-50/50/49.
In Table 4.2.C, the proposed change deletes surveillance requirements for " Flow Bias Comparator" and " Flow Bias Upscale" and revises test frequency requirements as follows:
Calibration frequency changes from "once/3 months" to "once/ operating cycle" for the APRM Upscale and Downscale rod block trip functions.
Calibration frequency changes from "once/6 months" to "once/ operating cycle" for the RBM Upscale and Downscale rod block trip functions.
Instrument check frequency changes from'"once/ day" to "N/A" for the RBM Upscale, Downscale and Inoperative rod block trip functions.
The additional proposed change in Table 4.2.C is described under the second group of changes, Group B.
18.
Page 3.2/4.2-59/59/58.
In " Notes for Tables 4.2.A Through 4.2.L, Except 4.2.D and 4.2.K",
Note 1 currently reads:
1.
Functional tests shall be performed once per month.
El-14
i l
The proposed. change revises Note 1 to read:
i 1.
For IRMs and SRMs, functional tests shall be performed once per month.
For APRMs and RBMs, functional tests shall be performed once per 6 months.
19.
Page 3.2/4.2-60/60/59.
In " Notes for Tables 4.2.A Through 4.2.L, Except 4.2.D and 4.2.K",
the proposed change deletes Note 15 and Note 20 which currently read:
- 15. The flow bias comparator will be tested by putting one flow unit in " Test" (producing M scram) and adjusting the test input to obtain comparator rod block.
The flow bias upscale will be verified by observing a local upscale trip light during operation and verified that it will produce a rod block during the operating cycle.
- 20. Calibration of the comparator requires the inputs from both recirculation loops to be interrupted, thereby removing the flow bias signal to the APRM and RBM and scramming the reactor.
This calibration can only be performed during an outage.
20.
Page 3.2/4.2-68/68/67.
The proposed change revises a sentence in "3.2 Bases" describing control rod block functions.
The sentence currently reads as follows:
The trip logic for this function is 1-out-of-n:
e.g.,
any trip on one of six APRMs, eight IRMs or four SRMs
.will result in a rod block.
The revised sentence will read:
The trip logic for this function is 1-out-of-n:
e.g.,
any trip on one of four APRMs, eight IRMs or four SRMs will result in a rod block.
El-15
21.
Page 3 2/4.2-73/73a/72.
The proposed change adds the following new discussion of APRM and RBM rod block function test frequency at the end of the current "4.2 Bases" section:
The electronic instrumentation comprising the APRM rod block and Rod Block Monitor functions together with the recirculation flow instrumentation for flow bias purposes is monitored by the same self-test functions as applied to the APRM function for the RPS.
The functional test frequency of every six months is based on this automatic self-test monitoring at 15 minute intervals and on the low expected equipment failure rates.
Calibration frequency of once per operating cycle is based or. the drift characteristics of the limited number of analog components, recognizing that most of the processing is performed digitally without drift of setpoint values.
Group B-The following proposed changes are related to planned implementation of APRM and RBM technical specification (ARTS) improvements recommended by GE and to proposed operation in an expanded core power / flow domain, the Maximum Extended Load Line Limit (MELLL) region.
RBM modifications and APRM netpoint changes required to implement the proposed ARTS /MELLL operation are included in the NUMAC PRNM design.
The proposed expanded operating region above the rated (design) power / flow control line is bounded by the rated (100%) power line and the power / flow control line which passes through the 100% power /75% core flow point (approximately the 121% rod line).
BFN TS changes proposed in support of ARTS /MELLL operation are provided below.
These changes are supported by analyses performed for BFN by GE as documented in Reference 3 and are consistent with the recommendations contained therein.
TS page numbers are presented in the format "Page x.z/y.z-U1/U2/U3" where U1, U2, and U3 are the respective Unit 1, Unit 2, and Unit 3 page numbers.
Where only one number is given, the TS page number is the same in all three units.
El-16
22.
Pages-1.0-7 and 1.0-8:
The proposed change deletes the following definitions under the heading of
" Thermal Parameters":
3.
Core Maximum Fraction of Limiting Power Density (CMFLPD) 5.
Core Maximum Fraction of Critical Power (CMFCP) 23.
Page 1.1/2.1-2.
Under Limiting Safety System Setting (LSSS) 2.1.A.1 a, the APRM flow biased scram setpoint equation currently reads:
Ss(0.58W + 62%).
The proposed change revises this equation to read:
Ss(0.66W + 71%).
24.
Page 1.1/2.1-3.
Under the note in LSSS 2.1.A.1.b.
The proposed change adds the following to the list of thermal hydraulic design criteria.
It also changes the word "either" to "any" for grammatical consistency:
APLHGR within the limits of Specification 3.5.I.
e The proposed change also deletes the following sentence:
Surveillance requirements for APRM scram setpoint are F
given in Specification 4.5.L.
25.
Page 1.1/2.1-7.
The proposed change revises Figure 2.1-2 to show the new APRM Flow Bias Scram Setpoint.
4 26.
Page 1.1/2.1-16.
Under Bases Section 2.1.L the proposed change adds a new reference:
Maximum Extended Load Line Limit and ARTS Improvement Program Analyses for Browns Ferry Nuclear Plant, Units 1, 2,
and 3, NEDC-32433P.
El-17
i
'27.
Page 3.1/4.1-20/20/19.
The proposed change deletes the term "CMFLPD" from the sentence which currently reads, "The technical specification limits of CMFLPD, CPR, and APLHGR are determined...."
28.
Page 3.2/4.2-2.
In Limiting Condition for Operation (LCO) 3.2.C, the entry " DELETE - Now covered by note 7.c" is deleted.
29.
Page 3.2/4 2-25/25/24.
In Table 3.2.C requirements for the RBM functions currently read as follows-Minimum operable Channels Per. Trip J
Punction (S)
Function Trin Level Settina 2(7)
RBM Upscale (Flow Bias)
(13) 2 (7)
RBM Downscale (9) 23%
.I The proposed change revises the RBM functions tc reflect a change from flow-biased to power-biased setpoints.
The revised table entries are provided below.
)
Minimurn Operable I
Channels Per. Trip Function (S)
Function Trin Level Settina 2 (7)
RBM Upscale (Power Bias)
Low Power Range (13)
(14)
Intermediate Power Range (13)
(14)
High Power Range (13)
(14) 2 (7)
RBM Downscale (9) (13)
(15) 30.
Page 3.2/4.2-26/26/25.
In Note 7 of " Notes for Table 3.2.C" the proposed change adds, as Note 7.c, new conditions of power and Minimum Critical Power Ratio (MCPR) where the RBM is not required to be operable.
Previous Notes "7.c" and "7.d" are relabeled as "7.d" and "7.e",
respectively, but their text is not changed.
Note 7.c will read as follows:
El-18
7.c The RBM need not be OPERABLE if either of the following two conditions is met:
(1) Reactor thermal power is 2 90 percent of rated and MCPR is 2 1.44, or (2) Reactor thermal power is < 90 percent of rated and MCPR is 2 1.75.
31.
Page 3.2/4.2-27/27/26.
Note 13 in " Notes for Table 3.2.C" currently reads:
- 13. The trip level setting and clipped value for this setting shall be as specified in the CORE OPERATING LIMITS REPORT.
The proposed change revises Note 13 and adds new Notes 14 and 15.
The revised notes read as follows:
- 13. The RBM rod block trip setpoints and applicable power ranges are specified in the CORE OPERATING LIMITS REPORT (COLR).
- 14. Less than or equal to the setpoint allowable value specified in the COLR.
- 15. Greater than or equal to the setpoint allowable value specified in the COLR.
32.
Page 3.2/4.2-50/50/49.
In Table 4.2.C the parenthetic description of the RBM Upscale function is changed from " Flow Bias" to " Power Bias".
33.
Page 3.3/4.3-8.
The proposed change deletes existing LCOs 3.3.B.5 and SR 4.3.B.5 which are restated below:
3.3.B.5 During operation with CMFCP or CMFLPD equal to or greater than 0.95, either:
a.
Both RBM channels shall be OPERABLE; or b.
Control rod withdrawal shall be blocked.
El-19
4.3.B.5 During operation with CMFCP or CMFLPD equal to or greater than 0.95, an instrument functional test of the RBM shall be performed prior to control rod withdrawal and at least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> thereafter.
34.
Page 3.3/4.3-17.
The proposed change deletes the entire bases section 3.3/4.3-B.5 which reads:
The Rod Block Monitor (RBM) is designed The specified restrictions with one channel out of service conservatively assure that fuel damage will not occur due to rod withdrawal errors when this condition exists.
35.
Page 3.5/4.5-18.
The proposed change revises LCO 3.5.I to implement flow-and power-dependent ~ Average Planar Linear Heat Generation Rate (APLHGR) limits.
LCO 3.5.I currently reads:
3 j
...the Average Planar Linear Heat Generation Rate (APLHGR) of any fuel assembly at any axial location shall not exceed the appropriate APLHGR limit provided in the CORE OPERATING LIMITS REPORT.
The proposed change revises LCO 3.5.I to read:
...the Average Planar Linear Heat Generation Rate (APLHGR) of any fuel assembly.at any axial location shall not exceed the appropriate rated, flow-dependent or power-dependent APLHGR limit provided in the CORE OPERATING LIMITS REPORT.
36.
Page 3.5/4.5-19.
The proposed change revises LCO 3.5.K and SR 3.5.K to implement flow-dependent and power-dependent MCPR operating limits.
LCO 3.5.K currently reads:
The minimum critical power ratio (MCPR) shall be equal to or greater than the operating limit MCPR (OLMCPR) as provided in the CORE OPERATING LIMITS REPORT.
El-20 k
The proposed change revises LCO 3.5.K to read:
The minimum critical power ratio (MCPR) shall be equal to or greater than the appropriate rated, flow-dependent or power-dependent operating limit MCPR (OLMCPR) as provided in the CORE OPERATING LIMITS REPORT.
SR 4.5.K.2 currently reads:
The MCPR limit at rated flow and rated power shall be determined as provided in the CORE OPERATING LIMITS REPORT The proposed change revises SR 4.5.K.2 to read:
The operating limit MCPR shall be determined as provided in the CORE OPERATING LIMITS REPORT 37.
Page 3.5/4.5-20.
The proposed change deletes the APRM setpoint setdown requirements of LCO 3.5.L and SR 4.5.L.
These requirements currently read as follows.
3.5.L.
APRM Setpoints 1.
Whenever the core thermal power is 225%
of rated, the ratio of FRP/CMFLPD shall be 21.0, or the APRM scram setpoint equation listed in Section 2.1.A and the APRM rod block setpoint equation listed in the CORE OPERATING LIMITS REPORT shall be multiplied by FRP/CMFLPD.
2.
When it is determined that 3.5.L.1 is not being met, 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> is allowed to correct the condition.
3.
If 3.5.L.1 and 3.5.L.2 cannot be met, the reactor power shall be reduced to s25% of rated thermal power within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
El-21
~.
.... ~.. - -
.. ~.-. -....... -...
.. ~ ~ _...
O 4
4.5.L APRM Setpoints 2
FRP/CMFLPD shall be determined daily when the reactor is 2 25% of rated thermal power.
1 38.
Page 3.5/4.5-21/20/20a. The 45% core flow value in i
j SR 4.5.M.1.a is changed to 50%.
~
39.
Page 3.5/4.5-22/22a/21.
Figure 3.5.M-1, BFN Power / Flow Stability Regions, is modified to expand i
the Region II area to include the power / flow map area j
between 45% and 50%-core flow and above the 108% rod I
line.
Also, the figure is reformatted to improve readability, l'
l 40.
Page 3.5/4.5-33/31/34.
In Bases 3.5.I the proposed p
change adds the following description of power-and flow-dependent APLHGR limits at the end of the current section:
4 b
At less than rated power conditions, the rated APLHGR limit is adjusted by a power-dependent correction i
factor, MAPFAC(P).
At less than rated flow conditions, the rated APLHGR limit is adjusted by a flow-dependent correction f actor, MAPFAC(F).
!~
The most limiting power-adjusted or flow-adjusted value is taken as the APLHGR operating limit for the j
off-rated condition.
The flow-dependent correction factor, MAPFAC(F),
applied to'the rated APLHGR limit assures that (1) the 10 CFR.50.46 limit would not be exceeded during a LOCA initiated from less than rated core flow conditions and (2) -the fuel thermal mechanical design criteria would be met during abnormal operating transients initiated from less than rated core flow conditions.
MAPFAC (F) values are provided in the CORE OPERATING LIMITS REPORT.
The power-dependent correction factor, MAPFAC(P),
applied to the rated APLHGR limit assures that the fuel thermal mechanical design criteria would be met during abnormal operating transients initiated from less than rated power conditions.
MAPFAC (P) values are provided in the CORE OPERATING LIMITS REPORT.
El-22 v
e - -,.
m
-em-w
. =
41.
Page 3.5/4.5-34/32/35.
In Bases 3.5.K the proposed 4
change adds the following description of power-and flow-dependent MCPR limits at the end of the current section:
l At less than rated power conditions, a power-dependent MCPR operating limit, MCPR(P), is j
applicable.
At less than rated flow conditions, a j.
flow-dependent MCPR operating limit, MCPR (F), is applicable.
The most limiting power-dependent or flow-dependent value is taken as the MCPR operating limit for the off-rated condition.
i The flow-dependent limit, MCPR(F), provides the thermal margin required to protect the fuel from transients resulting from inadvertent core flow increases.
MCPR(F) values are provided in the CORE a
OPERATING LIMITS REPORT.
The power-dependent limit, MCPR(P), protects the fuel from the other limiting abnormal operating transients, including localized i
events such as a rod withdrawal error.
MCPR (P) values are provided in the CORE OPERATING LIMITS REPORT.
42.
Page 3.5/4.5-34/32/35.
The proposed change deletes Bases Section.3.5.L, which reads:
3.5.L.
APRM Setpoints 4
f The fuel cladding integrity safety limits of Section 2.1 were based on a total peaking factor within design limits (FRP/CMFLPD)2 1.0.
The APRM instruments must be adjusted 5
to ensure that the core thermal limits are not exceeded in a degraded situation when entry conditions are less conservative than design assumptions.
i i
El-23
43.
Page 6.0-26a,b/26a/26a.
The proposed change revises the description of the content of the CORE OPERATING LIMITS REPORT as indicated below:
Current Description Revised Description (1) The APLHGR for The rated APLHGR limit; Specification 3.5.I.
the Flow-Dependent APLHGR Factor, MAPFAC (F) ; and the Power-Dependent APLHGR i
Factor, MAPFAC(P) for Specification 3.5.I.
(2) The LGHR for The LHGR limit for Specification 3.5.J.
Specification 3.5.J.
(3) The MCPR Operating The rated MCPR Operating Limit for Limit; the Flow-Dependent Specification 3.5.K/
MCPR Operating Limit, 4.5.K.
MCPR(F); and the Power-y Dependent MCPR Operating Limit, MCPR(P) for Specification 3.5.K/4.5.K.
(4) The APRM Flow Biased The APRM flow biased rod Rod Block Trip block trip setting for Setting for Specification 2.1.A.1.c Specification and Table 3.2.C.
2.1.A.1.c, Table Table 3.2.C, and Specification 3.5.L.
i (5) The RBM Upscale (Flow The RBM downscale trip Bias) Trip Setting and setpoint, high power trip clipped value for this setpoint, intermediate power setting for Table trip setpoint, and low power I
3.2.C.
trip setpoint, and applicable reactor thermal power ranges for each of the setpoints for Table 3.2.C.
4 El-24
II.
REASON FOR THE PROPOSED CHANGE The proposed TS changes described under Group A are reqdired to support replacement of the existing power range neutron monitoring equipment.
As discussed in Reference 10, BFN is planning to replace the power range monitor portion of the NMS with a GE digital NUMAC PRNM retrofit system.
The new equipment will include capability for an automatic Oscillation Power Range Monitor (OPRM) trip to detect and suppress possible thermal hydraulic instabilities in the reactor.
The new OPRM trip function, when enabled, will implement the Boiling Water Reactor Owners Group (BWROG) defined
" Stability Option III" alternative.
The OPRM portion of the system will be operated in the " indicate only" mode during the first cycle'of operation, and OPRM stability trip function will not be enabled.
Therefore, this proposed change in TS does not include revisions to incorporate the Stability Option III automatic trip function.
All other PRNM functions will be operable, and this package provides the required TS changes for these functions.
The planned modification involves replacement of all of the existing power range monitor electronics with new NUMAC digital PRNM hardware.
The current equipment is mounted in a 5-bay panel in the main control room of each unit.
The modification removes and replaces virtually all of the existing power range monitor equipment within the confines of the main control room panels, but with minor exceptions, leaves the plant level cabling and interfaces undisturbed.
All power range monitor functions are maintained, including LPRM detector signal processing, LPRM averaging, APRM trips, and RBM logic and interlocks.
Recirculation flow signal processing, previously accomplished using separate hardware within the power range monitor control panels, is integrated into the APRM chassis in the new PRNM system.
The six existing APRM channels in the current system are replaced with four APRM channels, each using 1/4 of the total LPRM detectors.
The APRM function is retained, but four 2-out-of-4 trip output voters are added to the input El-25
i!
l to the RPS, two in each RPS trip system.
The trip outputs from all four APRM channels are sent to each voter so that each of the inputs to the RPS is a voted result of all four APRM channels.
The number of recirculation flow instrument inputs to the APRMs is increased from two total-flow instrument loops (four transmitters) to four total-flow instrument loops (eight transmitters),
permitting one recirculation total-flow instrument loop to be assigned to each APRM channel.
)
The reasons for the various individual proposed TS changes described in Group A are as follows:
The required minimum number of operable instrument channels for the APRM scram trip functions is changed to 3 because the new configuration will have 4 total APRM
)
channels combined in a 2-out-of-4 logic.
In the proposed configuration, a minimum of 3 of the 4 channels is required operable to meet single failure criteria for the RPS trips initiated by APRMs.
Note 11 to Table 3.1.A is i
revised regarding the minimum channel number to highlight the way in which the proposed APRM instrument channel configuration differs from the rest of the RPS instrument channels.
Note 13 in Table 3.1.A is revised because in the new configuration, the minimum required number of operable LPRMs changes, and fewer than the required minimum number of operable LPRMs results in an inoperative alarm, not an inoperative trip.
The new required minimum number is provided in a description added to Bases 3.1.
This new requirement is based on analyses performed for BFN by GE which cover the worst case combinations of LPRM input failures and LPRM bypass conditions.
Fewer than the required minimum number of LPRM inputs (20 total, with 3 per axial level) causes an instrument channel inoperative alarm and control rod block, but does not result in an automatic inoperative trip input to the 2-out-of-4 voters.
An automatic APRM inoperative trip is required to occur when the APRM channel is incapable of providing a trip
)
based on normal functions.
However, when the minimum number of LPRM detectors is reached, the APRM still is capable of providing normal protective trips.
- Thus, El-26
applicable LCO action times are allowed to evaluate and correct the situation.
This is consistent with the requirements of Reference 2.
The APRM 2-out-of-4 voter trip function requires a minimum operable' number.of 2 instrument channels per RPS trip system.
This requirement is consistent with the proposed new hardware configuration.
There are 2 voters per RPS trip system, and requiring 2_ voters operable in each of
-the_two RPS trip systems ensures that single failure criteria is met.
Table 3.1.A~and associated Note 12 are revised to reflect the logic of the 2-out-of-4 voter
-trips.
New action' statements are added to Table 3.1.A associated with inoperability of the APRM trip functions or the 2-out-of-4 voters.
If one1 required APRM channel is inoperable,. the new action requirements permit a maximum of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to restore the configuration to one that will withstand single failure (by repairing or tripping an inoperable channel).
If two or more required APRM channels are inoperable (so_that 2-out-of-4 trip capability is lost), 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> is allowed to restore trip capability or to initiate an alternate action.
If one voter channel is inoperable, a 12-hour repair / action time is provided.
If two voter channels (one in each RPS trip system) are inoperable, a 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> repair / action time is allowed.
If two voter channels (both in the same RPS trip system) are inoperable (so that APRM trip capability in the associated RPS trip system is lost), 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> is allowed tx) restore trip capability or take an alternate action.
These allowed repair / action times are. consistent with i
times used in Standard TS and are supported by the PRNM unavailability. analysis as documented in Reference 2.
'l Note 5 of Table 3.1.A is revised to reflect a hardware change which eliminates the APRM Downscale scram trip.
Eliminating the APRM Downscale scram trip reduces the potential for spurious scrams and is consistent with deleting the requirement for a APRM Downscale Trip Function as-documented'in Reference 2.
Operability requirements in Table 3.1.A for APRM Trip Functions;in the Refuel mode are deleted, consistent with the recommendations of Reference 2.
The functions, El-27 1
however, will remain operable in the new hardware configuration.
The proposed TS change revises Note 21 associated with APRM High Flux (15% rated power) and Inoperable Trip Functions in the Refuel mode and adds application of Note 21 to the 2-Out-of -4 Voter Trip Functio)..
Note 21 is revised to replace the previous indirect requirement for removing shorting links with a direct requirement to enable the SRM high flux scram function under appropriate conditions.
The revision to Note 21 retains the existing alternative to take credit for Operability of appropriate APRM Trip Functions (not otherwise required in Refuel mode) in lieu of enabling the noncoincidence SRM high flux scram.
The existing specification does not require the SRM scram function to be enabled when a control rod is withdrawn from a cell which does not contain fuel.
The proposed change also provides additional conditions where enabling the SRM scram function in Refuel mode is not required.
If shutdown margin has been demonstrated and the one-rod-out rod block is Operable, then criticality cannot occur, and enabling of the SRM scram function is not required.
Surveillance frequencies in Table 4.1.A associated with the APRM scram functions are changed to the values recommended in and supported by Reference 2.
These increases in APRM surveillance intervals take credit for the self-test features of the GE NUMAC PRNM equipment to reduce the administrative burden, the manpower requirements, and the risks of spurious trips associated with more frequent surveillances.
New requirements for functional testing of the 2-out-of-4 voter trip logic, described in new Note 10, Table 4.1.A, are consistent with the recommendations in Reference 2.
Functional testing of the RPS scram contactors, previously part of the APRM weekly functional test, continues to be performed weekly by test of the 2-out-of-4 voter trip output, as described in new Note 11.
APRM functional testing " group" assignments are deleted because the existing Bases discussions of these " groups" will no longer apply for testing of the NUMAC APRM equipment.
New separate discussions of the basis for APRM surveillance requirements are added into the appropriate TS Bases sections.
El-28
Because the proposed modification deletes separate flow bias networks by integrating all of the flow-related logic into the APRM/RBM chassis, there are no longer separate operability or surveillance requirements associated with the APRM flow bias function.
All of these functions are tested as part of the APRM/RBM functional tests and calibrations.
Thus, most requirements previously associated with separate APRM flow bias networks are deleted.
A requirement for once per cycle calibration of the flow bias signal is retained in Table 4.1.B, consistent with recommendations of Reference 2.
Bases sections and various notes applicable to the RPS instrumentation are changed to properly reflect details of the proposed NUMAC hardware.
Changes 8, 9,
and 13 provide new details consistent with the proposed configuration and requirements for the NUMAC APRM equipment.
Changes 10 and 11 adjust existing TS Bases descriptions consistent with the proposed APRM configuration and functional changes.
The control rod block operability and surveillance requirements (Table 3.2.C and associated sections) for APRMs and RBMs are changed consistent with the proposed new APRM/RBM hardware configuration.
Reasons for the changes are, in general, similar to the reasons for changes in the requirements for APRM scram trip functions described above.
In Table 3.2.C the minimum required number of APRM rod block trip channels is changed from "4" to "3"
consistent with the capability to bypass one of the four APRM instrument channels.
This is consistent with, but more conservative than, the minimum of two APRM rod block trip channels proposed in Reference 2.
Table 3.2.C functional and surveillance requirements for Flow Bias Comparator and Flow Bias Upscale are deleted, consistent with recommendations of Reference 2.
I i
Bases sections and various notes for the Control Rod Block Instrumentation are changed to properly describe the I
configuration and features of the proposed NUMAC PRNM hardware.
l El-29 4
j
i Proposed TS changes described under Grouo B are related to implementation of ARTS /MELLL improvements.
These chances are proposed concurrent with the NUMAC PRNM related changes because equipment design, and interface and setpoint modifications required to implement these proposed TS changes will be included as part of the NUMAC PRNM design.
j Implementation of the ARTS improvements requires physical modification of the RBM system.
The proposed modification changes the RBM trip setpoints from flow-biased to power-biased values and reconfigures the LPRM inputs to the RBMs.
These propcscd changes are intended to eliminate limitations of the current RBM system, which was designed in the mid-1960s.
Since that time there have been significant advances in the fields of two-phase heat transfer and electronics.
The current RBM signals do not always correlate well with thermal margin changes during control rod withdrawal, and the system performs its function only at the expense of significant operational penalties due to excessive conservatism inherent in the design of the current system.
The modified RBM system will provide improved correlation of RBM response with changes in fuel thermal margin and will enhance operator confidence in the system by reducing the frequency of nonessential rod blocks.
Also, the proposed changes will upgrade the performance of the RBM system and will provide new RBM setpoint and operability requirements such that the Rod Withdrawal Error (RWE) will not be the limiting transient.
In addition to changes in the RBM system's configuration, setpoints and operability requirements, ARTS improvements eliminate the current TS requirement to lower (setdown) the flow-biased APRM scram and rod block trips when the Core Maximum Fraction of Limiting Power Density (CMFLPD) exceeds the Fraction of Rated Power (FRP).
To support elimination of this requirement, as well as to support the change to power-biased RBM setpoints, new power-dependent and flow-dependent fuel thermal limits are proposed to be implemented.
The proposed replacement of the current APRM trip setdown requirement by more meaningful power-and flow-dependent thermal limits eliminates a need for manual setpoint adjustments and is anticipated to enhance administration of thermal limits compliance.
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The proposed expansion of allowable operation to the MELLL region provides enhanced ability to achieve and maintain operation at rated power.
Because rated power can be maintained with recirculation flow adjustments over a wider flow range, less frequent control rod adjustments are required to compensate for reactivity depletion, and the need for power reductions to perform control rod withdrawal is decreased.
The plant will be able to operate longer at rated power, will have more flexibility to schedule load reductions, and will be able to operate in a more safe, efficient, and economical manner.
The reasons for the various individual proposed TS changes described in Group B are as follows:
1 The TS " Definitions" section is revised to delete definitions for Core Maximum Fraction of Limiting Power Density (CMFLPD) and Core Maximum Fraction of Critical i
Power (CMFCP).
These definitions are no longer needed because the LCOs and SRs which use these definitions are deleted as part of the proposed change.
The LSSS APRM flow-biased setpoint equation 2.1.A.1.a is changed.
This change is needed to support operation in the MELLL region by providing adequate operating margin between boundaries of the MELLL regior and the flow biased APRM scram.
Figure 2.1-2 is revised to show the revised APRM flow-biased scram setpoint.
The APRM flow-biased rod block setpoint, specified in the Core Operating Limits Report (COLR), is also revised as part of the proposed change.
The note in LSSS 2.1.A.1.b is revised because the referenced LCO section (4.5.L) is deleted as part of the proposed change.
The APLHGR limit, now flow-and power-dependent, is listed as one of the thermal hydraulic design criteria on which the new APRM setpoint is based.
The LSSS Bases Section 2.1.L is revised to add a new reference to GE's ARTS /MELLL analysis for BFN which forms the analytical basis for the proposed changes.
In Bases Section 4.1, a reference to "CMFLPD" is deleted, consistent with its deletion from definitions, LCOs and SRs.
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In LCO 3.2.C a reference to note 7.c associated with a previous deletion is being deleted.
The reference is not needed in the existing TS or the proposed TS.
Table 3.2.C for Control Rod Block Instrumentation, is revised to reflect the change from flow-biased to power-biased RBM setpoints.
As discussed in Reference 3, the change to power-biased RBM setpoints improves the correlation of RBM rod blocks with available thermal margin.
At low core power levels where thermal margins are high, long rod withdrawals are permitted; while at l
high core powers where thermal margins are relatively low,
.only short rod withdrawals are allowed.
The new RBM Upscale power-biased setpoints apply over three power 4-ranges, low, intermediate and high.
These three power-range-dependent upscale trip functions are listed under the existing RBM Upscale trip function heading.
The flow-biased RBM setpoints are found in the COLR, and Note 13 for Table 3.2.C is revised to indicate that the 4
j.
proposed power-biased RBM Upscale trip function setpoints and applicable power ranges will be provided in the COLR.
Similarly, new Note 14 to Table 3.2.C is provided to specify that the RBM Upscale Trip Level Settings must be less than or, equal to the setpoint allowable values provided in the COLR.
Also, the RBM Downscale Trip Level setpoint-value is referenced by a new Note 15, which j
requires that the Downscale Trip Level Setting be greater 4
than or equal to the setpoint allowable value provided in j
the COLR.
This proposed change results in all RBM setpoints being located in the COLR.
Note 7 for Table 3.2.C is revised to add new conditions of reactor thermal power and MCPR where operability of the RBM is not required.
This requirement is consistent with the discussion in Section 10.5 of Reference 3 with the exception that an additional adjustment has been added to the MCPR values in notes 7.c. (1) and (2) to account for potential increases in the base MCPR Safety Limit of 1.07 due to variations in core loadings.
The adjusted values are applicable for MCPR Safety Limit values of 1.10 or less.
In Table 4.2.C the REM Upscale function description is revised to reflect the change from flow-biased to power-biased setpoints.
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In TS Section 3.3/4.3, " Reactivity Control", the proposed j
change deletes LCO 3.3.B.5, SR 4.3.B.5, and Bases Section 3.3/4.3-B.S.
The requirement was instituted as part of an earlier revision of flow-biased RBM setpoint values to provide additional RBM limits margin by providing operating limitations.
With the implementation of power-biased RBM setpoints, this specification is no longer needed and is not required by the ARTS analysis.
LCO 3.5.I is revised to reference the proposed implementation of flow-dependent and power-dependent APLHGR limits.
LCO 3.5.K is likewise revised to reflect the proposed implementation of flow-dependent and power-dependent operating MCPR limits.
SR 4.5.K.2 is revised to be compatible with the proposed LCO change.
Bases Sections 3.5.I and 3.5.K are revised to add new discussions of the proposed flow-dependent and power-dependent APLHGR and MCPR limits.
As discussed in Reference 3, implementation of these flow-and power-dependent thermal limits permits more direct administration of thermal limits compliance and supports deletion of the APRM setpoint setdown requirement.
LCO 3.5.L (the APRM setpoint setdown requirement) and associated SR and Bases sections are deleted as justified by the evaluation in Section 5.3 of Reference 3.
The deletion of this LCO eliminates the need to make APRM Setpoint adjustments under Certai". Core power Conditions Eliminating this requirement rcauces administrative and manpower burdens, and eliminates the risks of spurious trips associated with the previously required APRM setpoint adjustments.
Figure 3.5.M-1, BFN Power / Flow Stability Regions, is modified to expand Region II to include the power / flow map segment between 45% and 50% core flow, and above the 108%
rod line.
Also, in SR 4.5.M.1.a the core flow value is raised from 45% to 50% to match the SR to the revised Figure. This change is made to preserve the BFN commitment to use the improved BWROG Guidelines for Stability Interim Corrective Actions.
The BWROG Guidelines include this added Region II segment for plants operating under the MELLL expanded power / flow map.
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In TS Section 6.9.1.7 the description of the Core Operating Limits Report is changed to reflect the proposed change to flow-and power-dependent APLHGR and MCPR operating limits, the proposed elimination of the APRM setpoint setdown requirement, and the proposed changes from flow-biased to power-biased RBM setpoints.
j III.
SAFETY ANALYSIS l
Group A Changes:
These proposed TS changes are associated with replacement of the existing power range neutron monitoring system with a GE digital NUMAC PRNM retrofit design.
GE Licensing Topical NEDC-32410P provides detailed descriptions, discussion, bases, and data applicable to the GE NUMAC PRNM retrofit designs.
NRC has reviewed the subject Topical Report, (issued as NEDC-32410P-A, Reference 2) and issued a Safety Evaluation Report (SER) (Reference 11) which indicated the acceptability of the generic design and accompanying TS changes.
In the SER, NRC requested that licensees address six plant specific issues to take credit for the evaluations provided in Topical Report. of this enclosure provides TVA's responses to the utility actions listed in the SER.
A safety evaluation of the proposed modifications and TS changes is summarized below:
For the functions addressed by the proposed TS change, the NUMAC PRNM has the same design basis requirements as the original power range neutron monitoring system.
The original system was designed to meet IEEE 279-1971 compliance; therefore the requirements of this standard apply to the replacement design.
In addition, NRC Regulatory Guide 1.152 -1985 is applied as a requirement.
Reference 2 includes a " compliance matrix" that correlates the requirements of the Regulatory Guide to the NUMAC PRhH implementing program.
Section 4 of Reference 2 further discusses the design bases and regulatory requirements applicable for the NUMAC PRNM system.
All previous APRM upscale scram trips are retained in the new design.
The proposed design and related LCOs permit one APRM instrument channel to be bypassed at any time for El-34
maintenance or testing while retaining the ability to withstand single failure of one of the remaining instrument channels.
However, because of requirements to meet single failure criteria, bypass of any 2-out-of-4 voter is not permitted.
LCO action times and required actions for fewer than the required number of APRM trip functions or 2-out-of-4 voter functions are consistent with unavailability analyses documented in Reference 2 and with Standard Technical Specifications.
The proposed TS change deletes the previous requirement for APRM operability in Refuel mode, consistent with the recommendation of Reference 2.
In eliminating the APRM operability requirements in Refuel mode, the proposed TS j
change makes explicit the requirement to enable the SRM l
high flux scram function under appropriate conditions.
However, the existing alternative to take credit for APRM trips in lieu of enabling the SRM high flux scram function is retained, provided that the appropriate APRM trip functions are maintained operable in the Refuel mode.
The proposed change also deletes the previously required APRM downscale scram trip in the Run mode.
No postulated event takes credit for this downscale trip, and eliminating the logic for the trip reduces the potential for spurious scrams in testing, maintenance, or operation.
The proposed TS change extends required surveillance intervals of the APRM and RBM equipment to the maximum periods supported by Reference 2.
This reduction in surveillance frequency is supported by the increased reliability and the extensive self-test capability of the new hardware.
Testing of the RPS scram contactors via the APRM system is retained and is performed by weekly testing of the 2-out-of-4 voter trip output function.
Extending APRM surveillance intervals reduces the rotential for spurious trips while testing is being performed, thus enhancing the overall reliability of plant operations.
Group B Changes:
These proposed TS changes are associated with implementing ARTS improvements and with extending operation to the MELLL region of the power / flow map.
The NRC has previously approved implementation of ARTS /MELLL changes at other BWRs (References 4, 5, 6 and 7) and has El-35
i also approved antension of BFN's original operating region to the Extended Load Line Limit (ELLL) region (References 8 and 9).
l Reference 3 documents results of analyses and evaluations performed for BFN by GE to support the proposed ARTS /MELLL changes.
Appendix A of Reference 3 discusses major features of the modified RBM system, and Section 10 provides an in-depth discussion of the RBM system evaluation and requirements to support the ARTS improvement.
Sections 4 and 5 provide a description of APRM improvements and a detailed discussion of the new power-and flow-dependent thermal limits which support elimination of the previous APRM setpoint setdown requirements.
Reference 3 provides documentation of extensive analyses of operation in the MELLL region performed for BFN based on the Unit 2, Cycle 8 fuel core i
loading.
Specific allowable setpoints were generated in a separate GE calculation for BFN (Reference 12) and will be documented in the COLR report for individual fuel cycles.
As discussed in Reference 3, the analyses performed typically yield generic limits which will be applicable to future Unit 2 and Unit 3 core reloads.
Appropriate portions of these analyses will be reconfirmed in j
cycle-specific Reload Analyses.
l The evaluations documented in Reference 3 to justify the safety of operation in the MELLL region consist of two segments.
One segment is that which is not fuel dependent. The other segment is that which is fuel dependent, and therefore, fuel cycle dependent.
In general, the limiting anticipated operational occurrences (AOOs) MCPR calculation and the reactor vessel overpressure protection analysis are fuel cycle dependent.
These analyses as presented in Reference 3 are based on the BFN Unit 2, Cycle 8, core loading at the current rated core thermal power of 3293 megawatts thermal (MWt).
For non-fuel dependent evaluations such as containment responses, an uprated power level of 3458 MWt (105% of the current rated core thermal power) is used.
The non-fuel dependent evaluations are based on hardware design, geometrien, and system performance which are similar among the BFN units.
Thus, these non-fuel dependent evaluations are generically applicable to BFN Units 1, 2,
and 3 for MELLL region operation.
As noted previously, appropriate El-36
i portions of.these analyses will be reconfirmed in the.
cycle-specific' Reload Analyses.
Changes to setpoints, if necessary, will be presented in the cycle specific COLRs
[
in the same manner currently in place _for cycle-specific L
limit changes, i
I Evaluations of the specific TS changes associated with ARTS /MELLL implementation are summarized below:
The TS change revises the flow-biased APRM scram setpoint j
from.Ss 0.58W.+ 62% Rated Thermal Power (RTP) to l
Ss 0.66W +71 % RTP.
The flow-biased APRM scram setpoint maximum (clamped) value of 120% does not change.
The i:
change revises Figure 2.1-2 to show the new flow-biased j
In addition, the flow-biased'APRM i
rod block setpoints documented.in-the COLR will be changed.
These changes incorporate _new setpoints for the I
flow-biased APRM' scram and rod block functions based on the MELLL Analytic Limits documented in Reference 3 and l'
the setpoint calculations in Reference 12, and are based on the incorporation of NUMAC PRNM equipment.
For original plant operation with the maximum load line limited to the rated rod line, the setpoint for the flow-biased APRM scram'line was Ss 0.66W + 54% RTP.
With the first expansion of the power / flow map to allow operation up to the 108% rod line-(References 8 anc 9),
the flow-biased APRM flux scram line was modified to Ss 0.58W + 62%.. With the proposed expansion of the power / flow map to include the MELLL region depicted in-Figure 2-1 of Reference 3, the upper boundary of the-analyzed' operating domain is further extended to the 121% rod line.
The change in flow-biased APRM setpoints maximizes plant operating flexibility, restores the slopes of the flow-biased APRM scram and rod block setpoints to their--original design _ basis values, and restores the original design basis operating margin between the maximum extended load line and the APRM flow-biased scram setpoint.
The= purpose of the flow-biased APRM rod block is to block-control rod' withdrawal'when core power exceeds design bases and approaches _the scram level.
Should operation.
continue _in a manner such that the power / flow condition El-37
exceeds that specified by the APRM rod block setpoint, the flow-biased APRM scram trip setpoint would initiate a
~
The TS change revises LCO Table 3.2.C to reflect the change from flow-biased to power-biased RBM setpoints.
The RBM system is explicitly designed to mitigate the consequences of the rod withdrawal error (RWE) event and is not assumed to be available to mitigate any other AOOs.
The current RBM system configuration is described in detail in Section 10 of Reference 3.
The modified RBM system configuration is also described in Section 10 and Appendix A of Reference 3.
The modified RBM system uses advances in electronics to enhance instrumentation accuracy and improve the signal to thermal margin correlation.
The RBM modifications incorporate power-biased setpoints and provide a system response which more accurately reflects the actual margin to the safety limit at various power conditions.
Coincident with the modification of the RBM system, analyses were performed which generically bound the consequences of the RWE event.
These analyses established boundaries of power level and operating MCPR value.
Outside these values, no RWE event can result in exceeding the MCPR safety limit or jeopardizing the fuel thermal-mechanical design limits.
Inside these boundaries credit for the actions of the RBM is taken to limit the consequences of an RWE event.
This approach to analysis of the RWE event included determining appropriate MCPR requirements and corresponding RBM power-dependent setpoints for the modified RBM system for current fuel designs.
By appropriate selection of the setpoints, the RWE will not be the limiting event and will not determine the operating limit MCPR.
Appropriate RBM setpoints are selected based upon cycle-specific MCPR operating limit values (as determined from non-RWE events).
The RBM setpoints are thus reload-design dependent and are documented in the COLR.
The "S change revises Note 7 for Table 3.2.C to specify RTP and MCPR conditions where operability of the RBM system is not required.
Section 10.5 of Reference 3 documents that with RTP 2 90% and operating MCPR 2 1.40, or with RTP < 90% and operating MCPR 2 1.70, withdrawal of El-38
any single control rod from the full-in to the full-out position will not result in violation of the MCPR safety limit.
The BFN TS adds additional MCPR margin (resulting in MCPR values of 1.44 and 1.75) to account for potential increases for specific reload core analyses over the base 1.07 Safety Limit used in Reference 3.
Thus, under these upper limit conditions, the RBM system is not required to function in order to assure that an RWE has acceptable results.
The TS change deletes LCO/SR 3.3/4.3.B.5 and revises the Bases to eliminate existing restrictions on RBM operation near thermal limits.
These specifications are, in effect, additional requirements on the RBM system to require both RBM channels be operable or block control rod withdrawal when operating within 5% of thermal limits.
This allowed the previous RBM rod block lines to be raised based on the subject administrative TS provisions.
These operational provisions are not necessary with the ARTS analyses, and with use of power-biased RBM setpoints, can be eliminated.
The TS change deletes the requirement for flow-biased APRM scram and rod block setpoint setdown or APRM peaking factor (FRP/CMFLPD) adjustment currently specified in LCO 3.5.L.,
and, in lieu of these requirements, implements flow-and power-dependent thermal limits for APLHGR and MCPR.
LCO 3.5.I and LCO/SR 3.5.K are modified to reflect the change to flow-and power-dependent APLHGR and MCPR limits.
Related Bases sections are revised to reflect deletion of LCO 3.5.L and to include discussion of this new treatment of thermal limits.
Specifically, the change eliminates the requirement for setdown of the flow-biased APRM scram and rod block trip setpoints when the CMFLPD is greater than the FRP and substitutes adjustments to the rated MCPR and APLHGR operating limits that are flow-and power-dependent.
Analyses documented in Reference 3 demonstrate that with the setpoint setdown requirement eliminated and flow-and power-dependent thermal limits implemented, 1) MCPR safety limit will not be violated as a result of any AOOs, 2) all fuel thermal-mechanical design bases will remain within the licensing limits described in the GE generic fuel licensing report GESTAR-II, and 3) peak cladding temperature and maximum El-39
.-m_.
1 i
cladding oxidation fraction following.a Loss of Coolant
. Accident'(LOCA) will remain within the limits defined in i
' Figure 3.5.M-1, BFN Power / Flow Stability Regions, is modified to expand Region II to include the power / flow map segment between 45% and 50% core flow, and above the 108%
rod line.
Also, in SR 4.5.M.1.a the core flow value is 4
. raised from 45% to 50% to match the SR to the revised
{
Figure.
This change is made to maintain compatibility
{
with the improved BWROG Guidelines for Stability Interim Corrective Actions for plants' operating under the MELLL l
expanded power / flow map.
Prior to the implementation of MELLL, the existing APRM rod blocks and load line limitations physically restricted reactor entry in this l
area.
With the MELLL expanded power / flow map and
- j..
increased rod block lines, it becomes possible to operate in this area.
The BWROG Stability _ Guidelines, however, classify this area as a Region II restricted area, and to l-stay' consistent with BFN's commitments to implement the BWROG Stability Guidelines,.the TS Figure is modified to i
include this power / flow map region as Region II area.
]
The TS change revises the description of the Core
{
Operating Limits Report (COLR)in Section 6.9.1.'7.
The COLR already included the APLHGR'and MCPR operating limits i
and the RBM trip setpoints.
.The change to the COLR 4
description is an administrative revision to reflect the
}
changes in these limits and setpoints as described above.
i El-40
l IV.
NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION TVA has concluded that operation of Browns Ferry Nuclear 4
Plant (BFN) Units 1, 2,
and 3 in accordance with the proposed change to the technical specifications does not involve a significant hazards consideration.
TVA's conclusion is based on its evaluation, in accordance with 10 CFR 50. 91(a) (1), of the three standards set forth in 10 CFR 50.92(c).
1.
The proposed amendmant does not involve a sienificant increase in the probability or consequences of an accident previously evaluated.
Group A Changes:
These proposed TS changes are associated with the NUMAC PRNM retrofit design and involve associated changes to plant hardware and modification of the of the LCOs and SRs for equipment designed to mitigate events which result in power increase. transients.
For the APRM system, mitigative action is to block control rod withdrawal or initiate a reactor scram which terminates the power increase when setpoints are exceeded.
For the RBM system, mitigative action is to block continuous control rod withdrawal prior to exceeding the MCPR safety limit during a postulated Rod Withdrawal Error.
The worst case failure of either the APRM or the RBM systems is failure to initiate mitigative action (failure to scram or block rod withdrawal), but no such failure can cause an accident.
Thus, the proposed changes do not increase the probability of an accident previously evaluated.
For the APRM and the RBM systems, the NUMAC PRNM design, together with revised operability requirements (LCOs) and revised testing requirements (SRs), results in equipment which continues to perform the same mitigation functions with reliability equal to or greater than the equipment which it replaces.
Because there is no change in mitigation functions and because reliability of the functions is maintained, the proposed changes do not involve an increase in the consequences of an accident previously evaluated.
El-41
Group B Changes:
These proposed changes are associated with implementation of the ARTS /MELLL analysis.
The proposed change will permit expansion of the current allowable power / flow operating region and will apply a new methodology for assuring that fuel thermal and mechanical design limits are satisfied.
Reference 3 evaluates operation in the MELLL region with assumed implementation of the ARTS changes.
The conclusion of Reference 3 is that for all events and parameters considered, there is adequate design margin for operation in the MELLL region.
Because operation in the MELLL region maintains adequate design margin, the proposed changes do not increase the probability of an accident previously evaluated.
In support of operation in the MELLL region, the proposed change' modifies flow-biased APRM scram and rod block setpoints and implements new RBM power-biased setpoints.
No direct credit for the flow-biased APRM scram or APRM flow-biased rod block is taken in mitigation of design basis events, although it affords an additional margin to thermal limits for events that result in slow power increases such as loss of feedwater heaters.
Reference 3 includes a reanalysis of applicable events and concludes design margins are not degraded by the 4
proposed changes.
l The proposed changes to the RBM system potentially impact mitigation of the RWE.
However, per discussion in Reference 3, the proposed RBM changes, will assure that the RWE is not a limiting event and that the RBM continues to enforce rod blocks under appropriate conditions.
Therefore, the proposed changes do not increase the consequences of an accident previously evaluated.
2.
The proposed===nd==nt does not create the possibility of a new or different kind of accident from any accident previousiv evaluated.
The proposed PRNM and ARTS /MELLL changes involve modification and replacement of the existing power El-42
range neutron monitoring equipment, modification of the setpoints and operational requirements for the APRM and RBM systems, implementation of a new methodology for administering compliance with fuel thermal limits, and operation in an extended power / flow domain.
These proposed changes do not modify the basic functional requirements of the affected equipment, create any new system interfaces or interactions, or create any new system failure modes or sequence of events that could lead to an accident.
The worst case failure of the affected equipment is failure to perform a mitigation action, and failure of this mitigative equipment does not create the possibility of a new or different kind of accident.
Therefore, the proposed changes do not create the possibility of a new or different kind of j
accident from any accident previously evaluated.
3.
The proposed===nd==nt does not involve a sianificant reduction in a marain of safety.
Group A Changes:
These proposed TS changes are associated with the NUMAC PRNM retrofit design.
The NUMAC PRNM change does not impact reactor operating parameters or the functional requirements of the power range neutron monitoring system.
The replacement equipment continues to provide i
information, enforce control rod blocks, and initiate reactor scrams under appropriate specified conditions.
The proposed change does not revise any
.^
safety margin requirements.
The replacement APRM/RBM equipment has improved channel trip accuracy compared to the current system and meets or exceeds system requirements previously assumed in setpoint analysis.
Thus, the ability of the new equipment to enforce compliance with margins of safety equals or exceeds the ability of the equipment which it replaces.
Therefore, the proposed changes do not involve a reduction in a margin of safety Group B Changes:
These proposed changes are 4
associated with implementation of recommendations presented in the ARTS /MELLL analysis (Reference 3).
Operation in the MELLL region does not affect the ability of the plant safety-related trips or El-43
.~. -.
equipment to perform their functions, nor does it cause an increase in offsite radiation doses resulting from any analyzed event.
Analyses documented in Reference 3 demonstrate that, for operation in the MELLL region, adequate margin to design limits is maintained.
Implementation of the ARTS improvements provides flow-and power-dependent thermal limits which maintain existing margins of j
safety in normal operation, anticipated operational occurrences, and accident events.
Implementation of power-biased RBM setpoints improves the margin of safety in a postulated RWE by assuring that the RWE 3
is not a limiting _ event. Thus, the proposed changes do not involve a reduction in a margin of safety.
l V.
ENVIRONMENTAL IMPACT CONSIDERATION The proposed change does not involve a significant hazards consideration, a significant change in the types of or j
significant increase in the amounts of any effluents that may be released offsite, or a significant increase in individual or cumulative occupational radiation exposure.
Therefore, the proposed change meets the eligibility I
criteria for categorical exclusion set forth in 10 CFR 51.22 (c) (9) f rom environmental review.
Therefore, pursuant to 10 CFR 51.22(b), an environmental assessment of the proposed change is not required.
El-44
VI.
REFERENCES 1.
TVA letter to NRC, dated June 2, 1995, Browns Ferry Nuclear Plant (BFN), - Units 1, 2,
and Unit 3 -
Technical Specification (TS) 353 - Power Range Neutron Monitor (PRNM) Upgrade With Implementation of Average Power Range Monitor (APRM) and Rod Block Monitor (RBM) TS (ARTS) Improvements and Maximum Extended Load Line Limit (MELLL) Analyses.
2.
Licensing Topical Report, Nuclear Measurement Analysis And Control Power Range Neutron Monitor (NUMAC PRNM) Retrofit Plus Option III Stability Trip Function, Volumes 1 and 2, NEDC-32410P-A, October 1995. Including applicable parts of NEDC-32410P, Supplement 1, May 1996.
5 3.
GE Report, Maximum Extended Load Line Limit and ARTS Improvement Program Analyses for Browns Ferry Nuclear Plant Unit 1, 2 and 3, NEDC-32433P (included herein as Attachment 1).
4 4.
Letter from NRC to Carolina Power & Light Company, dated October 23, 1990, Issuance of Amendment No. 147 to Facility Operating License No. DPR-71 R?garding Maximum Extended Operating Domain.
5.
Letter from NRC to Carolina Power & Light Company, dated Octraer 12, 1989, Issuance of Amendment No. 168 to Facility Operating License No. DPR-62 Regarding 1
Maximum Extended Operating Domain, 6.
Letter from NRC to Detroit Edison Company, dated May 15, 1991, Amendment No. 69 to Facility Operating License No. NPF-43.
7.
Letter from NRC to PECO Energy Company, dated August 10, 1994, Expanded Operating Domain (ARTS /MELLLA) Technical Specifications, Peach Bottom Atomic Power Station, Unit 2.
4 8.
Letter from NRC to TVA, dated December 18, 1990, Issuance of Amendment (TAC No. 76934) (TS 285)
-[ Extended Load Line Limit Analysis - Amendment 181 to BFN Unit 2 Technical Specifications]
El-45
9.
Letter from NRC to TVA, dated February 24, 1995, Issuance of Technical Specification Amendment for the Browns Ferry Nuclear Plant Units 1, 2 and 3 (TAC Nos.
M89251, M89252, and M89253) (TS 339) (Extended Load Line Limit and Revised Fod Block Monitor Operability Requirements (Units 1 and 3); Deletion of Specific Values.... (Units 1, 2, and 3)]
10.
Letter from TVA to NRC, dated July 10, 1996, Browns 4
Ferry Nuclear Plant (BFN) - Units 1, 2,
and 3 -
1 Installation Schedule for the Stability Long-Term-Solution For NRC Generic Letter (GL) 94-02 11.
Letter from NRC to General Electric, dated September 5, 1995, Acceptance of Licensing Topical Report NEDC-32410P, Nuclear Measurement Analysis and Control Power Range Monitor (NUMAC-PRNM) Retrofit Plus Option III Stability Trip Function (TAC No.
M90616).
12.
GE Calculation, APRM Neutron Flux, Flow-Biased and Scram Clamp and Rod Block, and RBM Neutron Flux Downscale, Power and Trip Setdown Calculations, ARTS /MELLL(NUMAC) ---- Current-Rated Condition for Tennessee Valley Authority, Browns Ferry Nuclear Plant, EDE-28-0990, Revision 1, Supplement F, August 1995 El-46
%.-