ML20217C219
| ML20217C219 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 09/11/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20217C205 | List: |
| References | |
| NUDOCS 9710010267 | |
| Download: ML20217C219 (22) | |
Text
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panacg y k UNITED STATES s* NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. SomeHe01 e...+
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ,
RELATED TO AMENILM,31 NO. No TO FAClllTY OPERATING LICENSE NO. OPR 52 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT. Ugli 2 DOCKET NO. 50 260
1.0 INTRODUCTION
By letter dated June 2. 1995 the Tennessee Valley Authority (the licensee) requested amendments of the Technical S Nuclear Plant (BFN) Units 1. 2, and 3. pecifications The pror,osed (TS) for theprovides amendment Browns Ferry changes required to implement an improved power range neutron monitor (PRNM) system, designated by the licensee as Group A changes,. The proposed amendment also includes changes re block monitor TS (ARTS), quired for revised average power range monitor and rod and maximum e.. tended load line limit (MELLL) analyses, which the licensee designated as Group B changes.
The licensee submitted revisions to the original submittal on March 6,1997, and supplemental information on May 13, 1997 and August 20. 1997. The-revisions and supplemental information do not affect the staff's proposed finding of no significant hazards consideration.
This safety evaluation addresses T3 amendments for BFN Unit 2 only.
Implementation of the PRNM and ARTS /MELLL upgrade for BFN Uni'. 3 is planned for the fall of 199B, it is expec wd that improved TS, submitted by the licensee on September 6,1996, will W in effect by that time. Therefore, the custom TS changes requested in the June 2. 1995 and March 6. 1997 letters will not be required for BFN Unit 3. An amenoment pro >osing PRNM and ARTS /MELLL changes in the improved TS format were submitted )y the licensee en April 11, 1997, and are expected to be incorporated into the BFN Unit 3 improved TS.
BFN Unit 1 is in an extended shutdown. The improved TS will be implemented before that unit restarts. Therefore, changes to the custom TS for implementation of the PRNM and ARTS /MELLL analysis are not required.
2.0 DESCRIPTION
OF GROUP A CHANGES The proposed Group A changes reflect design changes that upgrade the existing analog power monitoring system in BFN Unit 2 with a General Electric (GE)
Company Digital Nuclear Measurement Analysis and Control Power Range Neutron Monitor System (NUMAC-PRNMS), including an Oscillation Power Range Monitor (OPRM) function.
Enclosure 2 E
P 288 n:ho PDR ,
2 By letter dated September 5.1995, the staff approved GE licensing topical report (LTR) NEDC 32410P. " Nuclear Measurement Analysis and Control Power Range Neutron Monitor (NUMAC PRNM) Retrofit Plus Option 111 Stability Trip Function." The staff review of this topical report determined that NEDC 32410P contains acceptable guidance for replacing the existing power range monitors in a boiling water reactor (BWR) with a digital NUMAC PRNMS.
NEDC 32410P also contains guidance to ensure digital upgrade issues, relevant standards and guidelines, and TS are adequately addressed.
The licensee's proposed TS amendments applicable to the Average Power Range Monitor (APRM) portion of the BFN TS are to be implemented following installation of the NUMAC PRNMS. The OPRM functions will be operated in the
" indicate only" test mode for one fuel cycle. Following Nuclear Regulatory Comission (NRC) staff review and ap)roval of the operating data, the OPRM trip function will be connected to tie reactor protection system (RPS) channels, and OPRM specific TS amendments will be implemented. During this test period, the existing interim corrective actions for determining and mitigating power oscillations will remain in effect.
Using the existing local aower range monitors (LPRM) and the recirculation coolant loo) flows, the NJMAC PRNMS provides APRM and OPRM trip signals to the RPS. The A)RM system averages LPRM signals, processes flow signals from the reactor core recirculation flow instrumentation, and then compares the results to RPS trip set points. The OPRM detects and suppresses reactor core power instabilities using the Option III approach described in LTR NED0 31960. "BWR Ch'ners' Group Long-Term Stability Solutions Licensing Methodology," dated June 1991, which was approved by the NRC staff.
The GE NUMAC PRNMS consists of four APRM channels and four voter channels.
Trip signals from each of the four APRM channels are sent to all four voter channels. One voter module is dedicated to each RPS trip relay. A reactor trip occurs when two or more of the four APRM functions, or two or more of the four OPRM functions calculate a trip condition. The voters perform a vote of the OPRM channel trip outputs separate from the APRM trip out)uts. For example, an OPRM trip in one channel and an APRM trip in anotler channel will not result in a reactor trip from two of four voters in a trip state. .
3.0 EVALUATION OF GROUP A CHANGES As stated in the staff's safety evaluation of NEDC-32410P. to receive NRC approval of a NUMAC-PRNMS installation, the licensee must confirm:
- 1. The applicability of NEDC 32410P. including clarifications and reconciled differences between the specific plant design and the topical report design descriptions,
- 2. The anlicability of the BWR Owners' Group topical reports that address the NJiAC-PRNMS and associated instability functions, set points and margins,
" 3. Plant-s)ecific revised TS for the NUMAC-PRNMS functions are consistent with NE)C-32410P, Appendix H. and Supplement 1.
p
3-
- 4. Plant specific environmental conditions are enveloped by the NUMAC PRNMS equipment environmental qualification values.
- 5. Administrative controls are provided for manually bypassing APRH/0PRM channels or protective functions, and for controlling access to the APRH/0PRM panel and channel bypass switch, and
- 6. Any changes to the plant operator's panel have received human factors reviews per plant specific procedures.
The licensee's actions with regard to the above conditions are discussed in the following sections.
3.1 Acolicability of the NUMAC-PRNMS Desion to the BFN Plant Desian The staff compared the anlicable BFN design features with the corresponding design features in LTR NDC-32410P. The three BFN units are GE BWR/4s. a BWR design addressed in the LTR. Consistent with the LTR system description, the six APRM channels currently used in the BFN units will be combined into four 2 out of 4 logic channels that will provide inputs through dedicated RPS channel voters to the four RPS channels.
Additionally the licensee is increasing the number of recirculation flow instrument(eight channels channels transmitters). from two total flow channels (four transmitters) to four These >roposed design modifications conform to the NUMAC PRNMS design description in VEDC 32410P, and are compatible with the existing plant neutron monitoring system and RPS. Therefore, the staff finds that the NUMAC PRNMS design is applicable to the BFN units.
3.2 PRNMS Instability Functions. Set Points. and Harains The licensee will test the PRNMS instability function (0PRM), including the adecuacy of the setpoint values and margins during the first fuel cycle of OPPF operation. uting the methodology described in LTR NEDO-32465-A. "BWR Owners Group Reactor Stability Detect and Suppress Solutions Licensing Basis Methodology and Reload Applications, dated August,1995. At the end of the fuel cycle, folhing NRC staff review and ap3roval of the operating data, the OPRM trip function will M connected to the R)S channels, and OPRM TS changes will be implemented. The staff approved the initial period for OPRM confirmatory testing in the safety evaluation of NEDC 32410P, and, therefore, finds the licensee approach acceptable.
3.3 Plant Soncific Rev_ised Technical Soecifications 3.3.1 Paae 3,,l/4.1 3. Table 3 1.A.
The minimum nuxber of operable instrument channels per trip system requirement for the APRM High Flux (Flow Biased). High Flux (Fixed Trip). High Flux, and Inoperative trip functions were revised from two channels to three channels.
These changes are consistent with the required channels per trip system in LTR NEDC 32410P Custom TS (CTS) Table 3.1.A. Reactor Protection System (SCRAM)
't Instrumentation Requirements which was previously approved by the staff, and, therefore, are acceptable.
l The APRM Downscale function was deleted in accordance mth the staff approved !
LTR. This change, therefore, is also acceptable. l The two out of four voter function, with. associated operability recuirements, notes, operating modes, and action statements, was added, in accorcance with the staff approved LTR recommendations, and is therefore acceptable.
The APRM High Flux trip and Inoperative channels requirements for Refueling Mode operations have been deleted. This change is in accordance with the staff-approved LTR, and is, therefore, acceptable.
Note 1 Action E (1.E) was added for the APRM High Flux (Flow Biased) trip. ;
High Flux (Fixed Trip), High Flux tri), and Inoperative trip functions. '
Note 1 Action F (1.F) was added for tie voter function. These additions are consistent with the approved LTR CTS, and, therefore, are acceptable.
3.3.2 Paae 31/41-5. Note 1 Actions for Table 3.1. A.
Action 1.E and Action 1.F requirements were added to the Table 3.1.A Note 1 actions. BFN Action 1.E ap) lies to the APRM High Flux (Flow Biased) tri High Flux (Fixed Trip). Hig1 Flux trip, and Inoperative trip functions. p.This Action states:
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 />. If two or more channels are inoperable for one or more trip functions, restore trip capability within I hour.
l This Action statement note is consistent with the approved LTR CTS Table 3.1.A Action 1.E. and, therefore, is acceptable.
BFN Action 1.F states:
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 associate 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, 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 initiate alternate action listed in the table. If two required voter channels are w
inoperable in onealternate 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or initiate trip system, restore action tripthe listed in capabilitke.ithin tab These actions are consistent with the required actions in the approved LTR CTS, and, therefore, are acceptable.
3.3.3 h gt 3.1/4.1 5. Note 5 - Intermediate Renae Monitors (IRMS)
BFN Table 3.1.A Note 5 currently states:
i IRMs are bypassed when APRMs are onscale and the reactor mode switch is in the RUN position.
The proposed change revises Note 5 to state:
IRMs are b position, ypassed when the reactor mode switch is in the RUN This change is consistent with the existing BFN TS Bases, page 3.1/4.1-16, which state:
In the power range. the APRM s Reference Section 7.5.7 FSAR.Thus, ystemtheprovides IRM system required protection.
is not required in the RUN mode. .. .
The requested change, therefore, is acceptable.
3.3.4 Paae 3.1/4-1-6. Note 7. and Notes 11. 12. and 13 BFN TS Table 3.1.A Note 7.E (APRM 15 percent scram) is being deleted. This deletion reflects the deletion from Table 3.1.A of the requirement for the APRM scram function in the Refuel mode. Although not removed from the Notes in the approved LTR CTS. this change is consistent with the operability requirements in the approved LTR CTS Table 3.1.A (APRMs not required to be OPERABLE in Refueling mode), and, therefore is acceptable.
BFN TS Table 3.1.A Note 11 currently states:
The APRM downscale trip function is only active when the reactor mode switch is in RUN The proposed change states:
Each APRM r.hannel provides input to both trip systems.
This change reflects the deletion of the APRM downscale function from Table 3.1.A. and the addition of a note describing the connection of each APRM channel to both reactor trip systems. These chan approved LTR CTS, and, therefore, are acceptable.ges are consistent with the Revised Note 11 was added to the " Min. No Of Operable Instr. Channels Per Trip System" column of Table 3.1.A for the APRM High Flux (Flow Biased), High Flux (Fixed Trip). High Flux, and Inoperative trip functions. This change is consistent with the approved LTR CTS Table 3.1.A and, therefore, is acceptable.
BFN TS Table 3.1.A Note 12 currently states:
The APRM downscale trip function is automatically bypassed when the IRM instrumentation is OPERABLE and not high.
, l 6-The proposed change states:
Any combination.of APRM upscale or inoperative trips from two or 1
' more non bypassed APRM trip functions will trip all of the l 2 out of-4 voter trip functions.
This change reflects the deletion of the APRM downscale function from Table 1 3.1.A. and the addition of a note describing the connection of each APRM 1 channel to all four voters. These changes are consistent with the approved
. LTR CTS, and, therefore, are acceptable. !
i Revised Note 12 was added to the Tri !
I the 2 out-of-4 voter trip function. p Level Settingiscolumn This change of Table consistent 3.1.A &
with the '
approved LTR CTS Table 3.1.A and, therefore, is acceptable, j BFN TS Table 3.1.A Note 13 currently states:
Less than 14 OPERABLE LPRMs will cause a trip system trip.
} The proposed change states:
Less than the required minimum number of OPERABLE LPRMs will cause an instrument channel inoperative alarm.
l
' This change is consistent with the approved LTR CTS, and, therefore, is acceptable.
Revised Note 13 was added to the Trip Level Setting column of Table 3.1.A for i the inoperative trip function. This change is consistent with the approved LTR CTS Table 3.1.A and, therefore. is acceptable.
3.3.5 Paae 3.1/4.1-3 and Paae 3.1/4.1-6. Note 21 The pro osed change revises Note 21 in the Notes for Table 3.1.A. The existin Note 21 states, 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 5 X 105 cps. The SRMs shall be OPERABLE per Specification 3.10.B.1. The removal of eight (8) shorting links is required to provide noncoincidence high flux scram protection from the Source Range Monitors.
1 The licensee states that the proposed change revises Note 21 to be a direct j requirement for shorting link removal. The revised Note 21 states:
~
In the REFUEL Mode, unless adequate shutdown margin has been demonstrated >er S>ecification 4.3.A.1 and the one-rod-out control rod block is OPERA 3LE per Specification 3.10.A.1. whenever any control rod is withdrawn from a core cell containing one or more i
. . . - . . . - , _ _,~r . _. - , - --
7-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 (b) the indicated APRM trip functions shall be OPERABLE per the recuirements applicable in the STARTUP/ HOT STANDBY Mode. If the SRF noncoincidence high flux scram function is enabled, the SRMs shall be OPERABLE per Specification 3.10.B.1. The removal of eight (8) shorting links is required to provide noncoincidence high flux scram protection from the SRMS, The approved LTR CTS Note 21 states:
Unless adequate shutdown margin has been demonstrated per Specification (plant specific reference), whenever any control rod is withdrawn from a core cell containing one or more fuel assemblies, shorting links shall be removed from the RPS circuitry to enable the Source range Monitor (SRM) noncoincidence high flux scram function. The removal of eight (8) shorting links is required to provide noncoincidence high-flux scram protection from the SRMS.
Although the approved LTR CTS does not include the BFN pro osed alternative (b), which requires APRM High Flux (s15 % rated power) tri function operability if the eight SRM shorting links are not remove , the proposed revision to Note 21 does not change the existing BFN TS Table 3.1.A operab',lity requirements: therefore, the proposed change is acceptable.
In the cu is 5 x 10[ rent cps. BFN TS, the trip The proposed setpoint revision for thethis removes SRM High value Flux from thetrip BFN function TS.
This revision is consistent with the approved LTR CTS, and, therefore, is acceptable.
3.3.6 Pace 3.1/4.1-8. Table 4.1.A. APRM Surveillance Reauirements 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 weekly test of the scram contactors initiated from the 2 out-of-4 voters, and adjusts associated notes. These changes are described in the following paragraphs.
The existing Table 4.1.A assigns a Group (B) designation to the APRM High Flux (Flow Biased), APRM High Flux (Fixed trip), APRM Inoperative. APRM Downscale, and APRM Flow Bias trip functions. The Group (B) designation applies to devices that utilize an analog sensor followed by an amplifier and a bistable trip circuit. Replacement of these devices with digital equipment allows the removal of the Group (B) designation from these trip functions, and, therefore is acceptable.
The existing Table 4.1.A assigns a Group (C) designation to the APRM High Flux (15% Scram) function. As stated in the BFN TS Bases:
l
Y 8-Group (C) devices are active only during a given portion of the operational cycle. For exam)le, the IRM is active during the STARTUP/ HOT STANDBY and REFUEL (with any control rod withdrawn from a core cell containing one or more fuel assemblies) Modes and inactive during full power operation. Thus, the only test that is meaningful is the one performed prior to entering the applicable Mode (i.e., the tests that are performed prior to the use of this instrument). Since testing of the IRM functions is not practical in the RUN Mode, testing is not required to be completed until 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after entering the STARTUP/ HOT STANDBY Mode from the RUN Mode. Twelve hours is based on operating experience and in consideration of providing reasonable time in which to complete the test.
The NUMAC PRNMS APRM scram functions are self tested ap>roximately once each 15 minutes. Conse uently, the staff finds acceptable tie removal of the APRM High Flux (15%) trip function Group (C) designation.
The APRM Downscale trip function will be removed from Table 3.1.A.
Consequently,from requirements Table 4.1.A is acceptable. removal The existing of the APRM APRM Flow Downscale Bias trip function is being replaced by the APR1 High Flux (Flow Biased) trip function.
Consequently, removal of the APRM Flow Bias functional test requirements from Table 4.1.A is acceptable. .
The minimum functional test frequency for the- APRM trip functions was changed from once per week to once per 6 months. This chan approved LTR CTS testing frequency, and, therefore,ged is consistent with the is acceptable.
Testing requirements for the 2 out of-4 Voter trip function were added to Table 4.1.A. The corresponding changes are consistent with the approved LTR CTS, and, therefore are acceptable.
3.3.7 Pace 3.1/4-1-10. Table 4.1. A Notes 5. 6.10. and 11
- The proposed Note 5 states that the channel functional test of the tri) output relays shall include both the APRM channels and the 2 out of 4 voter clannels, I
which is consistent with the approved LTR CTS, and, therefore, is acceptable.
1 Note 6 was changed to reflect replacement of the existing APRM Flow Bias trip function with the APRM High Flux (Flow Biased) tri) function. The revised .
channel functional test is required to test both tie APRM channels and the 2-out of 4 voter channels plus the flow input function, excluding the flow l transmitters - This change is consistent with the approved LTR CTS, and,
! therefore, is acceptable.
i-
' Note 10 was added to Table 4.1.A for the 2-out-of-4 voter looic test. The Note 10 functional test requirement consists of testing of all combinations of two tripped inputs to the 2-out-of 4 voter logic in the voter channels. This i
change is consistent with approved LTR CTS Table 4.1.A Note 9 and its 4
application to the 2-out-of-4 voter logic testing, and, therefore. is .
acceptable.
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- 9 Note 11 was added to Table 4.1,. A for the 2 out of 4 Voter Trip Scram Contactor test. The Note 11 functional test requirement consists of manually tripping the 2 out of 4 voter trip outputs, one voter channel at a time in order to demonstrate that each scram contactor for each RPS trip system channel (A1.
A2 Bl. and B2) operates and produces a half scram. This requirement is consistent with approved LTR CTS Table 4.1.A Note 11 and its application to the 2 out of-4 voter trip scram contactor testing, and, therefore is acceptable.
3.3.8 Paae 3.1/4.1-11. Table 4.1.B. Calibration Reauirements The existing Table 4.1.B assigns a Group (B) designation to the APRM High Flux Dutput signal. APRM High Flux (Flow Biased) signal, and the LPRM signal. The Group (B) designation applies to devices that utilize an analog sensor followed by an amplifier and a bistable trip circuit. Replacement of these devices with digital equipment allows the removal of the Group (B) designation from these trip functions, and, therefore is acceptable.
Additionally..because the NUMAC PRNMS design processes LPRM signals differently than the existing power range monitor design, the LPRM signal calibration will be performed as part of the APRM High Flux channel calibration, Consequently, the proposed change acceptably indents "LPRM Signal" to incorporate the LPRM channel testing into the APRM High Flux channel testing.
3.3.9 Paae 3.1/4.1 12. Table 4.1.9 Note 7 Note 7 currently states:
The Flow Bias Signal calibration will consist of calibrating the sensors. flow converters. and signal offset networks during each operating cycle. The instrumentation is 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 calibration frequency.
The proposed Note 7 states:
The flow bias signal calibration will consist of calibrating the analog differential pressure flow sensors once per operating cycle. Calibration of the flow bias )rocessing system is done once per operating cycle as part of tie overall APRM instrumentation calibration.
The approved LTR CTS Note 7 states:
The flow Bias Signal Calibration will consist of calibrating the analog differential pressure flow sensors once per operating cycle. The output from these sensors is processed by the APRM chassis (same hardware as for the APRM channel) to provide a
j i
l 10 - '
digital total flow signal. The same hardware that performs the ,
rod block monitor (RBM) functions also com '
signals provided to each APRM. four total, topares each theother.
total flow Self-test monitoring of the APRM chassis includes the equipment that t performs the flow signal processing. Calibration of the flow bias processing system is done once per operating cycle as part of the overall APRM instrumentation calibration.
The first and last sentences of the pro)osed Note 7 are the same as the first and last sentences of the approved LTR CTS Table 4.1.B Note 7. The licensee incorporated the remaining discussion in approved LTR CTS Note 7 into the BFN TS Bases discussion. This intercedin recuirements on the Flow Bias Signal,g discussion and, therefore,does not impose calibration is appropriately adcressed in the BFN TS Bases. The proposed changes, therefore, are acceptable.
3.3.10 Pace 3.1/4.1-14. Descriotion of the APRM System This proposed change deletes the last sentence of the sixth paragraph which states:
Three APRM instrument channels are provided for each protection trip system.
The licensee proposes adding the following description of the APRM System:
The APRM system is divided into four APRM channels and four 2 out-of 4 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 tri)" in all four of the voter units, but no trip in)uts 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 in)ut signals from forty-three (43) local Power Range Monitors (L)RMs). A minimum of twenty (20) LPRM inputs with three (3) per axial level is required for the APRM instrument channel to be 0)ERABLE. 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.
The first paragra>h is consistent with the suggested description in the approved LTR CTS 3ases. The last paragraph is consistent with the APRM system descri tion in the anroved LTR STS Bases. The staff, therefore, finds the descri tion of the A>RM system to be acceptable.
j 3.3.11 Pace 3.1/4.1 15. Descriotion of the IRM System This proposed change revises the first two sentences of the first paragraph on this page, and deletes the third sentence of the paragraph. The current description states:
Each protection trip system has one more APRM than is necessary to meet the minimum number required per channel. Th1:, allows the bypassing of one APRM per protection tri) system for maintenance, testing or calibration. Additional IRi channels have also been provided to allow for bypassing one such channel... The bases for....
The proposed description states:
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 channel per protection trip system for maintenance, testing or calibration. The bases for....
These changes are consistent with the approved LTR CTS Bases, and, therefore, are acceptable.
3.3.12 Pace 3 1/4.1-16. APRM Downscale Function Descriotion The existing description of the APRM downscale function states:
Because of the APRM downscale limit of =3 yercent when in the RUN mode and high level limit of s15 oercent wien in the STARTUP mode, the transition between the STARTU) and RUN Modes must be made with the APRM instrumentation indicating between 3 percent and 15 percent of rated power.
The proposed revision states:
Because of the APRM downscale rod block limit of a3 percent when in the RUN mode and high level flux scram limit of s15 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 1 5 percent of rated power.
These changes are consistent with the approved LTR CTS Bases, and, therefore, are acceptable.
3.3.13 Pace 3.1/4.1-17. Tables 4.1. A and 4.1.B Descriotion The current BFN TS Bases state:
The channels listed in Tables 4.1.A and 4.1.B are divided into three groups for functional testing.
The proposed revision states:
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.
This revision is consistent with the aroposed APRM design and the corresponding revisions of the two ta)les, and, therefore, is acceptable.
3.3.14 Paaes 3.1/4.1-19 and 3.1/4.1 20. APRM and Voter Self test Functions and Periodic Manual Test Reauirements The proposed change deletes the description of APRM Flow Biasing Network calibration, and adds three paragraphs describing the APRM and voter self test functions and periodic manual test requirements. The first and third paragraphs are consistent with the approved LTR CTS Bases discussion. The second paragraph restates Note 11 from the revised Table 4.1.A. which discusses the use of the 2 out of 4 voter channels to test to RPS scram contactors.
This revision is consistent with the NUMAC-PRNMS APRM design, the 2-out of 4 voter desi therefore,gn, and the corresponding revisions of the Table 4.1.A, and, is acceptable.
3.3.15 Paae 3 2/4.2 25. Table 3.2.C Revisions Acolicable to the RPS The proposed revision changes the APRM rod block Minimum Operable Channels Per Trip Function from "4" to 3" and deletes requirements for the " Flow Bias Comparator" and the " Flow Bias U) scale" rod block functions. These changes are consistent with the NUMAC-PRIMS APRM design, and, therefore, are acceptable.
3.3.16 Paaes 3.2/4.2-26 and 3.2/4.2-27. Notes 5.10.b. and 10.c for Table 3.2.C Note 5 currently states:
.During repair...not more than one SRM or RBM channel nor more than two APRM or 1RM channels may be bypassed....
The proposed change states:
During repair...not more than one SRM, RBM, or APRM channel nor more than two IRM channels may be bypassed....
This change is consistent with the NUMAC PRNMS design configuration, which has been changed from three APRM channels per reactor trip system to two APRM channels per reactor trip system, and, therefore, is acceptable.
Note 10.b APRM inoperative trips (1), (2), and (3) currertly state:
(1) local " operate-calibrate" switch not in operate.
(2) Less than 14 LPRM inputs.
(3) Circuit boards not in circuit.
The proposed change revises these notes and adds Note 10.b (4). The proposed change states:
~
(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.
The approved LTR CTS Note 10.b (2) states: ,
(2) Less than (20] LPRM inputs or [3] LPRM detector inputs per level.
The proposed Note 10.b (2) is consistent with the approved LTR STS, which has been accepted by the staff, and, therefore, is acceptable.
Note 10.c. Rod Block Monitor (RBM) inoperative trip (1)-and (2) currently states:
(1) Local "cperate calibrate" switch not in operate.
(2) Circuit boards not in circuit.
The proposed change revises this note and adds Note 10.c (5). The proposed change states:
(1) local RBM chassis mode switch not in operate.
(2) RBM module unplugged....
(5) Self test detected critical fault.
This change is consistent with the NUMAC PRNMS design, and, therefore, is acceptable.
3.3.17 Egge 3 2/4.2 50. Table 4 2.C The proposed change deletes surveillance requirements for " Flow Bias Comparator" and " Flow Bias Upscale." The recirculation flow instrumentation for flow bias purposes is automatically tested at 15 minute intervals by the same self-test functions as applied to the NUMAC PRNMS APRM function for the RPS. This change, therefore, is acceptable.
This revision changas the calibration frequency for the APRM Upscale and Downscale Rod Block trip functions and the RBM Upscale and Downscale trip functions from "once/3 months" and from "once/6 months" respectively, to 1
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- "once/ operating cycle". These changes are consistent with the approved LTR CTS, and, therefore, are acceptable.
This revision also changes the instrument check frequency from "once/ day" to "N/A" for the RBM lbscale. Downscale, and Inoperative rod block trip functions. These c1anges are censistent w1*h the approved LTR CTS and, therefore, are acceptable. .
3.3.18 Paae 3.2/4.2 59. Notes for Tables 4.2. A thouah 4.2.L. Exceot 4.2.D and
.W The curre,it Note 1 states:
- 1. Functional tests shall be performed once per month.
The proposed change revises Note 1 to state:
- 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.
This change is consistent with the approved LTR CTS. and, therefore, is acceptable.
- 3.3.19 Paae 3.2/4.2 60. Notes for Tables 4.2.A thouah 4.2.L. Extent 4.2.0 and W
The proposed change deletes Note 15 and Note 20, which address analog flow bias comaarator testing. The flow bias comparator function is now performed by the NJMAC-PRNMS. These chan and, therefore, are acceptable.ges are consistent with the approved LTR CTS, 3.3.20 Paae 3.2/4.2-68. 3.2 Bases The proposed change revises the description of the control rod block functions in the BFN TS 3.2 Bases. The sentence to be revised currently states:
The trip logic for this function is 1-out of-n: e.g., any trip on one of the six APRMS, eight TRMs or four SRMs will result in a rod block.
The revised sentence states:
The trip logic for this function is 1-out-of n: e.g., any trip on one of the four APRMS, eight IRMs or four SRMs will result in a rod block.
This change is consistent with the approved LTR CTS, and, therefore, is acceptable.
3.3.21 Pace 3.2/4.2 73a. 4.2 Bases This proposed revision adds the following discussion to the end of the 4.2 Bases section:
The electronic instrumentation comprising the APRH 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 on the drift characteristics of the limited number of analog components, recognizing that most of the processing is performed digitally without drift of setpoint values.
This change is consistent with the NUMAC PRNMS design and with the approved LTR CTS, and, therefore, is acceptable.
The staff finds that the proposed BFN TS and associated Bases conform to the staff-approved model TS and approved LTR CTS in NEDO 32410P A, Appendix H, and Supplement 1. The staff further finds that the aro)osed amendments to the BFN TS are consistent with the design of the NUMAC-)RNiS, and the existing design of the BFN units, and, therefore, are acceptable.
3.4 Plant-Soecific Environmental Conditions On May 13, 1997, the licensee provided the BFN plant-specific environmental conditions for temperature, humidity, pressure, and radiation. These environmental conditions are compared to the NUMAC PRNMS environmental qualification values in the table below.
~
BFN NUMAC PRNM$
Temperature 15.6*C to 4*C 5*C to 50*C (60'F to 104'F) (41'F to 122'F)
Humidity 10% to 90% RH 10% to 901 RH (noncondensing)
Pressure 14.7 psia to 14.72 psia 13 psia to 16 psia Radiation 1E-3 Rads /hr (carbon) dose rate 1E 3 Rads /hr (carbon) dose rate 1
350 Rads (carbon) total integrated 1000 Rads (carbon) total integrated dose dose This table shows that the BFN environmental conditions are enveloped by the NUMAC-PRNMS qualification values, and, therefore, are acceptable.
The staff reviewed the seismic response spectra for the BFd units and conclude that the BFN seismic qualification is within the NUMAC-PRNMS seismic qualification envelope, and, therefore, is acceptable.
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The approved LTR states that new equipment and plant modifications should not produce unacceptable levels of noise emissions that could adversely affect NUMAC equipment, or the licensee is to take action to prevent these emissions from reaching potentially sensitive equipment. These measures apply for both \
noise susceptibility and emissions. The BFN design procedures require that all digital equipment systems to be installed or used within the plant shall be evaluated for susceptibility and emissions of electromagnetic interference (EMI) in accordance with the NRC-approved EPRI Guideline TR 102323. The staff finds this approach acceptable for ensuring the EMI environment conforms to the requirements of General Desi The staff reviewed the licensee'gn Criterion (GDC) 4 of 10 CFR 50 Appendix A.
s evaluation of environmental conditions in the BFN plants and concludes that the BFN environmental conditions are envelo>ed by the GE equipment qualification parameters established for the NUMAC-)RNMS modtfication.
As described in the approved LTR, the PRNMS uses the same panel interfaces as the existing power range monitor equipment. High frequency filters are installed on the ac power supply, and shielded cables for all signal leads will be used in lieu of testing nonsafety equipment noise effects on the PRINS.
The staff finds the licensee's evaluation of the EMI environment and the measures taken to reduce adverse EMI affects to be an acceptable approach for ensuring the NUMAC PRNMS EMI environment conforms to the requirements of GDC 4 for protection against adverse environmenul effects.
3.5 Administrative Controls In the safety evaluation of NEDC-32410P the staff found acceptable the NUMAC-PRNMS d? sign features that control access to setpoint adjustments, calibrations, and test points. Since the licensee has not proposed design changes that would override these controls, the staff finds that the licensee has acce) table controls for controlling access to the PRNMS panel and the APRM/0PRi channel bypass switch.
3.6 Confirmation of Human Factors Review The licensee stated that the BFN design change process and implementing
")rocedures require completion of a Human Factors Engineering (HFE) Process Checklist and perforc,ance of an HFE review of changes to the plant operator's panel. The licensee further stated that an HFE review, per appliceble BFN procedures, of the pro >osed changes to the operator's >anel will be performed, and documentation of tlat review will be included in tie fin 31 design package (s) for the PRNMS. The staff finds this commitment acceptable.
4,0 DESCkiPTION OF GROUP B CHANGES Group B proposed changes are related to the implementation of APRM and RBM TS (ARTS) improvements recomended by GE and the proposed operation in an expanded core power / flow domain, the Maximum Extended Load Line Limit (MELLL) region. APRM and RBM setpoint changes required to implement the proposed ARTS /MELLL operation are included in the NUMAC PRNM design.
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MELLL involves:
- 1. Operation above the 100% (control) rod line below 100% flow, with operation permitted at 100% power down to 75% flow in the MELLL region, and
- 2. Operation with increased flow (to 105% at full power) in the increased core flow (ICF) region.
HELLL and ICF involve changes to the APRM rod block and thermal power scram setpoints.
ARTS involves:
- 1. Implementation of power and flow dependent fuel thermal limits to eliminate APRM trip setdown.
- 2. Supports power dependent RBM trips rather than the current flow dependent trips.
- 4. Redefinition of RBM operability requirements.
In support of its request the licensee has submitted a description and evaluation of the changes, the proposed new TS. and a GE report NEDC 32433P describing the changes and presenting the analysis and evaluations used to justify the changes for the BFN Units, and o>eration with the revised analytical and physical systems and within t1e new limits resulting from the changes.
5.0 EVALUATION OF GROUP B CHANGES This section will only deal with the reactor systems aspects of the Group B proposed changes to the Units: that is, operation in the ex)anded operating domain of the power / flow map. These proposed changes for B N are not unique or new for GE reactors. They have all become part of standard " Operating Flexibility Options" and are listed as such in the GE standard application for reactor fuel (GESTAR 11). Extended operating regions. increased core flow have been approved on many BWRs over the past decade, and several ARTS upgrades have been reviewed and approved. The methodologies used for safety analyses involved in the justifications for the changes and the determination of new operating limits have been previously reviewed by the staff. The prol>osed new operating regions, and modes and limits of operation, and changes to the APRM and RBM systems are all bounded by changes previously approved for other BWRs.
The MELLL-ARTS improvements in addition to the >ower-flow operating region expansion consists primarily of the following c1anges:
s .
- 1. The APRM flow biased rod block and thermal >ower scram setpoints are changed (increased) to allow operation in tie expanded region. Th's change includes hardware changes for clamping the trips in the high flod >
region to provide appropriate setpoints in the region from 75 to 105 percent flow.
- 2. The APRM flow biased scram setpoint is replaced by flow and power dependent limits on Maximum Average Planar Linear Generation Rate (MAPLHGR) and Minimum Critical Power Ratio (MCPR). Multipliers, as a function of oower and multipliers as a function of flow modify the operating MA)LHGR and MCPR are developed from the anal Nide operating occurrences described in the BFN UFSAR.ysis These become a of the core.
part of the BFN TS (via the COLR). At any given power / flow state all four limits must be determined, with the most limiting governing the operation.
To justify operation of the BFN Units with ARTS /MELLL and to determine values fer the limits previously described. GE has evaluated the UFSAR core wide transients, considering the extremes within this MELLL scope. The evaluation determined the events most significantly impacted by MELLL. which are based on the BFN Unit 2 Cycle 8 at the current rated power of 3293 MWt. The following criteria were used to assure satisfying the applicable licensing requirements for the BFN Units:
- 1. MCPR safety limit shall not be violated as a result of any anticipated operational occurrence (A00):
- 2. All fuel thermal-mechanical design bases shall remain within the licensing limits described in the generic fuel licensing report GESTAR-II: and
- 3. Peak cladding temperatures and maximum cladding oxidation fraction following a LOCA shall remain within the limits defined in Federal Regulation 10 CFR 50.46.
The operating limits associated with operation in the MELLL region are presented in Table 5 3 of topical report NEDC-32433P.
In addition to the transient analysis. GE examined the effect of ARTS /MELLL on overpressure protection. thermal-hydraulic stability. LOCA. containment response, feedwater nozzle and sparger fatigue, flow induced loads and vibration, and standard relevant events in the accident category. These ev61uations considered the areas examined, and followed the methods used in previous staff approved reviews of similar operation extensions. It was determined that with the limits used and derived for the ARTS /MELLL improvement all required safety associated limits within the above areas are met. For thermal-hydraulic stability BFN is operating under the " Interim Recommendation for Stability Actions of NRC Bulletin No.87-07. Supplement 1.
These operations are applicable to the BFN Units operation with ARTS /MELLL. as is the case for other operating reactors with similar systems.
4 These evaluations and transient analyses have examined the same areas examined in previous ARTS /MELLL related reviews by the staff. The method used in the evaluation have been previously approved by the staff and the results and conclusion of the evaluation fall within expected ranges. There are no
< significantly new regions of operation or to those previously reviewed and approved. parameter values or limits comparedThis re safety evaluations contained in the GE re> ort NEDC 32433P justify the proposed ARTS /MELLL improvements and operation K1t11n the power flow and temperature boundaries and operating limits described in the report. As in previous reviews of similar ARTS /MELLL programs for other reactors the instrumentation changes, analyses, methods used, criteria and setpoints proposed are acceptable.
5.1 Technical Soecifications There are changes to limits and operability requirements necessary for ARTS /MELLL operation. These include:
- 1. Deletion of current setdown requirements.
2, New power and flow dependent MCPR and MAPLHGR limits,
- 4. New RBM limits and operability requirements.
Tiiere are a number of TS changes required to implement these changes.
However, most of the TS related changes are proposed to be in thc BFN Core 0)erating Limits Report (COLR). The new values for the RBM and the changes to tie MCFR and MAPLHGR limits, i.e., the new multipliers and limits, which are, or may be, cycle specific are proposed to be in the COLR, which is designed for such parameters. The MCPR and MAPLHGR values already appear in the COLR.
Directions for applying the multiplying factors and new limit curves are also provided in the COLR along with the corresponding limits. NEDC 32433P, which describes the changes and methodology, becomes a reference in the TS Bases.
The review has indicated that the parameters proposed for the COLR are likely -
to be cycle saecific and are directly related to parameters already ap> roved for the BFN COLR. It is appropriate that the instructions for using t1ese parameters to provide the iCPR and MAPLHGR limits for a given reactor state
>oint also be directly associated with the limits in the COLR. This review las also indicated that the material. organization of the material and values in the COLR are reasonable and provide an acceptable change to the COLR. It is thus concluded that the placement of these values in the COLR is acceptable.
5.2 Effect of i'indinas From Inst >ection Reoort 99900003/97-01 NRC Inspection Report (IR) 99900003/97-01 documents an inspection of GE conducted from March 10-14, 1997. The non proprietary version of this inspection report is dated June 11, 1997.
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In this inspection, inspectors focused on evaluation and implementation of RBM o>erability to prevent fuel cladding from exceeding 1 per cent plastic strain.
NRC personnel found deficiencies in GE's design interface with licensees using ARTS for RBM operability. The inspection found that GE itid not adequately inform licensees of the possible effect of ARTS on the strain limit, contributing to failures to ensure adequate TS controls were maintained for RBM operability. This deficiency was cited in a Notice of Nonconformance.
On August 20, 1997. TVA documented that design calculations for BFN Unit 2 had included consideration of the findings of IR 99900003/97-01, and that appropriate RBM operability limits were provided to ensure that the 1 per cent plastic strain limit is not exceeded. TVA also stated that RBH requirements will be reevaluated as necessary for future fuel cycles. Therefore, the deficiency described in IR 99900003/97-01 does not apply to BFN Unit 2.
5.3 Groun B Sumary The TVA has proposed MELLL, and ICF changes to the allowed operating region for BFN Unit 2 and o>erating and physical changes to change to ARTS operation, along with TS and C0.R changes to implement these changes. The staff has reviewed the information. including the GE reports submitted with these proposed changes. Based on this review, the staff concludes that appropriate material has been submitted to justify the changes, that the changes fall within the scope and bounds of past staff reviews in these areas, and that the changes to and values proposed for the BFN Units TS (and COLR) are acceptable.
The use of GE report NEDC-32433P in the TS Bases and in the COLR as a reference to the ARTS /MELLL changes, methodology and analyses approved here is also acceptable.
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6.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Alabama State official i
(Kirk Whatley) was notified of the proposed issuance of the amendment. The State official had no comments.
7.0 ENVIRONMENTAL CONSIDERATION
The amendments change requirements with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes the surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there Is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the a'endments involve no significant hazards
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consideration, and there has been no public comment on such finding l (60 FR 42609). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
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8.0 CONCLUSION
The Comission has concluded, based upon the considerations discussed above, that: (1) the amendments do not (a) significantly increase the probability or consequences of an accident previously evaluated. (b) create the possibility of (c) asignificantly new or different reduce akind of accident margin from of safety: (2 thereany)previously evaluated, or is reasonable assurance thatthehealthandsafety)ofthepublicwillnotbeendangeredbyoperation in the proposed manner: (J such activities will be conducted in compliance with the Comission's regulations: and (4) issuance of these amendments will not be inimical to the comon defense and security or to the health and safety of the public.
Principal Contributors: M. Waterman, R. Frahm. Sr.,-and J. Williams Dated: September 11, 1997