ML18031A554

Proposed Tech Specs,Revising Limiting Conditions for Operation & Surveillance Requirements of Rod Sequence Control Sys & Rod Worth Minimizer.Justification & NSHC Determination Encl

ML18031A554
Person / Time
Site:	Browns Ferry
Issue date:	06/04/1986
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML18031A553	List: ML18031A552 ML18031A554
References
TAC-61960, TAC-61961, TAC-61962, NUDOCS 8607110144
Download: ML18031A554 (27)

Text

ENCLOSURE 1 PROPOSED TECHNICAL SPECIFICATION REVISIONS BROGANS FERRY NUCLEAR PLANT UNIT 1, 2, AND 3

~ .'(TVA BFNP TS 220) 8b07110144 8b0b04 t PDR *DOCK 05000259 p eon !

PROPOSED CHANGES UNIT 1

LIHITING CONDITIONS FOR OPERATION SURVEILLANCE RE UIREHENTS 3.3.B. Control Rods 4.3.B Control Rods control rod directional control a~ Verify that the control rod valves disarmed electrically. is following the drive by This requirement does not apply observing a response in the In the refuel condition when the nuclear instrumentation reactor is vented. Two control each time a rod is moved rod drives may be removed as when the reactor Is long as Specification 3.3.A.I is operating above the pre-set met. power level of the RSCS.

2. The control rod drive housing b. Mhen the rod i s . fu I I y support system shall be in place withdrawn the first time during reactor power operation after each refueling outage or when the reactor coolant or after maintenance, system is pressurized above observe that the drive does atmospheric pressure with fuel not go to the overtravel in the reactor vessel, unless position.

all control rods are fully inserted and Specification 2. The control rod drive housing 3.3.A.I is met. support system shall be inspected after reassembly and Mhenever the reactor is in the the results of the inspection startup or run modes below 20$ rated recorded.

power the Rod Sequence Control System (RSCS) shall be operable, except that the RSCS constraints may be suspended 3.a. I The Rod Sequence Control System by means of the individual rod bypass (RSCS) shall be demonstrated to switches for be operable for a reactor startup by the following checks:

(I) special criticality tests, or a~ Per formance of the comparator (2) control rod scram timing per check of the group notch 4.3.C.I. circuits within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to control rod withdrawal for the Mhen RSCS is bypassed on individual purpose of making the reactor rods for, these exceptions RMH must be critical.

operable per 3. 3.B. 3.b and a second party verification may not be used in b. Selecting and attempting to lieu of RMH. withdraw an out-of-sequence control rod after withdrawal of the first insequence control rod.

Ce Attempting to withdraw a control rod more than one notch prior to other control rod movement after the group notch mode is automatically initiated.

122

LIMITING CONDITIONS FOR OPERATION SURVEILLANCE RE UIR H 3.3.8 Control Rods 4.3.8 Control Rods

2. The Rod Sequence Control System (RSCS) shall be demonstrated to be operable for a reactor shutdown by tho following checks:

a. Performance of the comparator check of the group notch circuits within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to automatic initiation of the group notch mode.

b. Attempting to insert a control rod more than one notch prior to othor control rod movement after

b. Whenever the reactor is the group notch mode'is in the startup or run automatically initiated.

modes below 2(C rated power tho Rod Worth c. Selecting and attempting to move Hinimimr (RWH) shall bo an out-of-sequence control rod operable. With the RWH after insortlon of the first inoperable, verify insequonce control rod after control rod movement and roaching a black and white rod compliance with the pattern.

prescribed control rod pattern by a second '3.b. I The Rod Worth Hinimlzor (RWH) shall licensed operator or bo demonstrated to be operable for a other technically reactor startup by the following qualified member of the checks:

plant staff who is present at the reactor By demonstrating that the control consolo. control rod patterns and Othorwise, control rod sequence input to the RWH movomont may bo only by computer are correctly loaded actuating tho manual following any loading of tho scram or placing the program into tho computer.

reactor modo switch in the shutdown position. b. Within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to withdrawal of control rods for tho purpose of making the reactor critical, vorify propor annunciation of the selection error of at least one out-of-sequenco control rod.

Ce Within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to withdrawal of control rods for the purpose of making tho reactor critical, the rod block function of the RWH shall be verified by moving an out-of-sequence control rod.

123

'I

~ ~

~

~

LIHITING CONOITIONS FOR OPERATION SURYEILLANCE REQUIREMENTS

'$.>.B Control Rods 4.>.B Control Rods 3.b.2. The Rod Worth Minimizer (RWH) shell be demonstrated to be operable for a reactor shutdown by the following checks:

a. By demonstrating that the control rod patterns and sequence input to the RWH computer are correctly loaded following any loading of the program into the computer.

b. Within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to RWM automatic initiation when reducing thermal power, verify proper annunciation of the selection error of at least one out-of-sequence control rod. 0 Co Within one hour after RWM automatic initiation when reducing thermal power, the rod block function of the RWM shall be verified by moving an out-of-sequence control rod.

3.b.5. When the RWH is not operable a second licensed operator or other technically qualified member of the plant staff shall verify that the correct rod program is followed except as specified in 5.>.B.>.a.

123a

LIMITING CONOITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.3.8 Control Rods 4.3.8 Control Rods ce If Specifications 3.3.8.3.a through .b cannot be met the reactor shall not be started, or 4. Prior to control rod if the reactor is in the run or withdrawal for startup or startup modes at less than 2(C during refueling, verify that rated power, control rod at least two source range movement may be only channels have an observed the manual scram or by'ctuating count rate of at least three placing the reactor mode s~itch counts per second.

in the shutdown position.

5. When a limiting control rod

4. Control rods shal I not be pattern exists, an instrument withdrawn for startup or functional test of the RBM refueling unless at least two shall be performed prior to source range channels have an withdrawal of the designated observed count rate equal to or rod(s) and at least once per greater than three counts per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> thereafter.

second.

C. Scram Insertion Times

5. During operation with limiting control rod patterns, as I. After each refueling outage all determined by the designated operable rods shall be scram time qualified personnel, either : tested from the fully withdrawn position with the nuclear system

a. Both RBM channels shall be pressure above 800 psig. This operable or testing shall be completed prior to exceeding 4(4 power. Below 20%

b. Control rod withdrawal power, only rods in those shall be blocked. sequences (AI2 and A34 or BI2 and 834) which were fully C. Scram Insertion Times withdrawn in the region from IS@

rod density to 5'od density I. The average scram insertion shall be scram time tested. The time, based on the sequence restraints imposed upon deenergization of the scram the control rods in the I00-50 pilot valve solenoids as percent rod density groups to the time zero, of all operable preset power level may be removed control rods in the reactor by use of the individual bypass power operation conditions switches associated with those shall be no greater than: control rods which are fully or partially withdrawn and are not 5 Inserted From Avg. Scram Insertion within the l00-50 percent rod Times (net) density groups. In order to 5 0.375 bypass a rod, the actual rod axial 20 0.90 position must by known; and the 50 2.0 rod must be in the correct 90 3.500 in-sequence position. As required by 3.3.B.3.a a second licensed operator may not be used in lieu of RWM for this testing.

124

PROPOSED CHANGES UNIT 2

I HIT ING CONDITIONS FOR OPERATION SURVEILLANCE RE UIREHENTS 3.3.8. Control Rods 4 '.8 Control Rods control rod directional control a. Verify that the control rod valves disarmed electrically. is following the drive by This requirement does not apply observing a response in the in the refuel condition when the nuclear instrumentation reactor is vented. Two control each time a rod is moved rod drives may be removed as when the reactor is long as Specification 3.3.A.I is operating above the pre-set mot. power level of the RSCS.

2. The control rod drive housing b. Mhon the rod is .fully support system shall bo in place withdrawn the first time during reactor power operation aftor each refueling outage or when tho reactor coolant or after maintenance, system is pressurized above observe that the drive does atmospheric pressure with fuel not go to the ovortravel in the reactor vessel, unloss position.

all control rods are fully insortod and Specification 2. The control rod drive housing 3.3.A.I is mot. support system shall be inspected after reassembly and 3.a Mhenover tho reactor is in tho tho results of the inspection startup or run modes below Zlg ratod recorded.

power the Rod Soquenco Control Systen (RSCS) shall be operable, except that the RSCS constraints may bo suspended 3.a.l Tho Rod Sequence Control System by means of the individual rod bypass (RSCS) shall be demonstrated to switchos for be operable for a reactor startup by the following chocks:

(I) special criticality tests, or Por formance of tho comparator (2) control rod scram timing por check of tho group notch 4.3.C.I. circuits within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to control rod withdrawal for the Mhen RSCS is bypassed on individual purpose of making the reactor rods for thoso exceptions RMH must be critical.

operable por 3.3.8.3.b and a second party verification may not bo used ln b. Selecting and attempting to lieu of RMH. withdraw an out-of-sequence control rod aftor withdrawal of the first insoquonce control rod.

c Attempting to withdraw a control rod moro than ono notch prior to other control rod movement after the group notch mode is automatically initiated.

122

N FO OP RATION SURVEILLANCE RE UIREHENTS

$ .5.8 Control Rods 4.5.8 Control Rods

2. The Rod Sequence Control System (RSCS) shall bo demonstrated to be operable for a reactor shutdown by the following checks:

a. Performance of tho comparator check of the'roup notch circuits within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to automatic initiation of the group notch mode.

b. Attempting to insert a control rod more than one notch prior to other control rod movomont aftor

b. Mhenover the reactor is tho group notch mode is in the startup or automatically initiated.

run'odes below 2(4 rated power the Rod Morth c. Selecting and attempting to move Hinimizor (INH) shall bo an out-of-sequence control rod operable. Mith the RMH after insertion of the first inoporable, verify 'nsoquonco control rod after control rod movemont and roaching a black and white rod compliance with tho pattern.

proscribed control rod pattorn by a socond >.b.l Tho Rod Morth Hinimizor (RWH) shall licensed operator or be demonstrated to bo operable for a other technically reactor startup by the following qualifiod member of the chocks:

plant staff who is present at the reactor By demonstrating that the control console. control rod patterns and Otherwise, control rod soquenco input to the RWH movomont may bo only by computer aro correctly loaded actuating the manual following any loading of tho scram or placing tho program into tho computer.

reactor modo switch in the shutdown position. b. Mithin 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to withdrawal of control rods for the purpose of making the reactor critical, vorify proper annunciation of the soloction error of at loast ono out-of-soquonco control rod.

Ce Mithin 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to withdrawal of control rods for tho purpose of making tho reactor critical, tho rod block function of tho RMH shall be 123 verified by moving an out-of-sequence control rod.

LIMITING CONDITIONS FOR OPERATION S I 3.3.8 Control Rods 4.3.8 Control Rods 3.b.2. The Rod Worth Minimizer (RWH) shall be demonstrated to be operable for a reactor shutdown by the following checks:

a~ By demonstrating that the control rod patterns and sequence input to the RWM computer are correctly loaded following any loading of the program into the computer.

b. Within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to RWH automatic initiation when reducing thermal power, verify proper annunciation of the selection error of at least one out-of-sequence control.

rod.

c Within one hour after RWH automatic initiation when reducing thermal power, the rod block function of the RWH shall be verified by moving an out-of-sequence control rod.

5.b.3. When the RWH is not operable a second licensed operator or other technically qualified member of the plant staff shall verify that the correct rod program is followed except as specified in 3.3.B.3.a.

123a

LIHITING CONDITIONS FOR OPERATION SURVEILLANCE RE UIREMENTS

3. 3.B Control Rods 4.3.B Control Rods C, If Specifications 3.3.B.3.a through .b cannot bo met tho reactor shall not bo started, or 4. Prior to control rod if the reactor is in the run or withdrawal for startup or startup modes at less than 2(C during refueling, verify that rated power, control rod at least two source range movement may be only by channels have an observed actuating the manual scram or count rate of at least three placing the reactor mode switch counts per second.

in the shutdown position.

5. When a limiting control rod

4. Control rods shall not be pattern exists, an instrument withdrawn for startup or functional test of the RBH refueling unless at least two shell be performed prior to sourco range channels have an withdrawal of the designated observed count rate equal to or rod(s) and at least once per greater than three counts per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> thereafter.

second.

C. Scram Insertion Times

5. During operation with limiting control rod patterns, as I. After each refueling outage all detormined by the designated operable rods shal I be scram time qualified personnel, either : tested fran the fully withdrawn position with the nuclear system

a. Both RBH channols shall be pressure above 800 psig. This operable or testing shall bo completed prior to exceeding 4(4 power. Below 2(4

b. Control rod withdrawal power, only rods in those shall be blocked. sequences (AI2 and A34 or BI2 and 834) which were fully C. Scram Insertion Times withdrawn In the region from IOlg rod density to 5% rod density I. The average scram insertion shall be scram time tested. The time, based on the sequence restraints imposed upon deenergization of tho scram the control rods in the IOO-50 pilot valvo solenoids as percent rod density groups to tho time zero, of all operablo preset powor lovol may be removed control rods in the reactor by use of tho individual bypass power operation conditions switches associated with those shall bo no greator than: control rods which aro fully or partially withdrawn and are not 5 Inserted From Avg. Scram Insertion within the l00-50 percent rod Times (net) density groups. In order to 5 0.375 bypass a rod, the actual rod axial 20 0.90 position must by known; and the 50 2.0 rod must be in the correct 3.500 in-sequence position. As required by 3.3.B.3.a a second licensed operator may not be used in lieu of RWH for this testing.

124

PROPOSED CHANGES UNIT 3

LIHITING CONDITIONS FOR OPERATION SURVEILLANCE RE UIREMENTS

2. The control rod drive housing 2. The control rod drive housing support system shall be in place support system shall be during reactor power operation or inspected after reassembly when the reactor cooling system is and the results of tho pressurized above atmospheric inspection recorded.

pressure with fuel in the reactar vessel, unless all control rods are fully inserted and 5.a. I The Rod Sequence Control Specification S.'3.A.I is met. System (RSCS) shall be demonstrated ta be operable 5.a Whenever the reactor is in tho for a reactor startup by the startup or run modes below 2(5 following checks:

rated power the Rod Sequenco Control System (RSCS) shall bo a. Performance of the comparator operablo, excopt that the RSCS check af the group notch constraints may be suspended by circuits within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior means of tho individual rod bypass ta control rod withdrawal for switches for tho purpase of making tho reactor critical.

(I) special criticality tests, ar b. Selecting and attempting to (2) control rod scram timing per withdraw an out-of-sequenco 4.>.C.I. control rod after withdrawal of tho first insoquenco When RSCS is bypassed on control rod.

individual rods for these exceptions RWH must be operable c. Attempting to withdraw a per S.S.B.b.b and a second party control rod more than one verification may not be used in notch prior to other control lieu of RWH. rad movement after the group notch mode is automatically initiated.

123

SURVEILLANCE RE UIREHENTS Reactivi Control 4.5. Reactivi Control

2. The Rod Sequence Control System (RSCS) shall be demonstrated to be operable for a reactor shutdown by the following checks:

a. Performance of the comparator check of the group notch circuits within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to automatic initiation of the group notch mode.

b. Attempting to insert a control rod more than one notch prior to other control rod movement after

b. Whenever the reactor is the group notch mode is in the startup or run automatically initiated.

modes below 2'ated power the Rod Worth c. Selecting and attempting to move Hinimizer (RWH) shall be an out-of-sequence control rod operable. With the RMH after insertion of the first inoperable, verify insequence control rod after control rod movement and reaching a black and white rod compliance with the pattern.

prescribed control rod pattern by a second >.b.l The Rod Worth Hinimizer (RWH) shall licensed operator or be demonstrated to be operable for a other technically reactor startup by the following qualified member of the checks:

plant staff who is present at the reactor By demonstrating that the control console. control rod patterns and

'Otherwise, control rod sequence input to the RWH movement may be only by computer are correctly loaded actuating the manual following any loading of the scram or placing the program into the computer.

reactor mode switch in the shutdown position. b. Within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to withdrawal of control rods for the purpose of making the reactor cr'itical, verify proper annunciation of the selection error of at least one out-of-sequence control rod.

Ce Within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to withdrawal of control rods for the purpose of making the reactor critical, the rod block function of the RWH shall be verified by moving an out-of-sequence control rod.

124

ND TIONS FOR OPERATION SURVEILLANCE RE UIREHENTS S.b.2. The Rod Worth Minimizer (RWH) shall be demonstrated to be operable for a reactor shutdown by the following checks:

ao By demonstrating that the control rod patterns and sequence input to the RWH computer are correctly loaded following any loading of the program into the computer.

b. Within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to RWM automatic initiation reducing thermal 'hen power, verify proper annunciation of the selection error of at least one

'ut-of-sequence control rod.

c Within one hour after RWH automatic initiation when reducing thermal power, the rod block function of the RWM shall be verified by moving an out-of-sequence control rod.

5.b.5. When the RWM is not operable a second licensed operator or other technically qualified member of the plant staff shall verify that the correct rod program is followed except as specified in 5.5.8.>.a.

125

LIHITING CONDITIONS FOR OPERATION SURVEILLANCE RE UIREHENTS 4.$ .8 Reactivit Control Ce If Specifications 5.S.B.3.a through .b cannot be met the reactor shall not be started, or if the reactor is in the run or startup modes at less than 2(4 rated power, control rod movement may be only by actuating the manual scram or placing the reactor mode switch in the shutdown position.

126

ENCLOSURE 2 Description and Justification Browns Ferry Nuclear Plant (BFN)

Units 1, 2, and 3 Descri tion of Chan e Section 3.3.B.3.a is being revised to improve readability and to change a reference to be consistent with the new numbering scheme (page 122 unit 1, 123 unit 3). 'age Unit 2 only, page 122 section 3.3.B.3.a is being revised to specify when the Rod Sequence Control System (RSCS) constraints may be bypassed. for individual control rods. This provision is already included in units 1 and 3 technical specifications (TS).

Sections 4.3.B.3.a and 4.3.B.3.b for units 1 and 3, and section 4.3.B.3.a for unit 2, are being revised to require a more suitable surveillance to prove RSCS operability for a startup or shutdown, respectively (pages 122 and 123 for units 1 and 2, pages 123 and 124 for unit 3).

Section 3.3.B.3.b is being deleted (page 123 units 1 and 2, page 124 unit 3).

Section 3.3.B.3.c is being reidentified as 3.3.B.3.b, and is being revised to more clearly specify acceptable alternatives when the Rod Worth Minimizer (RWM) is not operable (page 123 units 1 and 2, page 124 unit 3).

Sections 4.3.B.3.c is being re-identified as 4.3.B.3.b for units 1 and 3, and all units are being revised to require a more suitable surveillance to prove RWM operability for a startup or shutdown, respectively (pages 123 and 123a units 1 and 2, pages 124 and 125 unit 3).

Section 4.3.B.3.d for units 1 and 3, and section 4.3.B.3.c for unit 2, are being reidentified as 4.3.B.3.b.3, and are being revised to more clearly specify surveillance requirements for continued rod movement with the RWM inoperable (page 123a units 1 and 2 page 125 unit 3).

Section 3.3.B.3.d is being reidentified as 3.3.B.3.c, and is being revised to change actions to be taken if 3.3.B.3.a 6, b cannot be met (page 124 units 1 and 2, page 126 unit 3).

To improve the readability of sections 3.3.B.3 and 4.3.B.3, for units it has been necessary to introduce a new page, number 123a, 1 and 2 only,

ENCLOSURE 2 (Continued)

Reason for Chan e This change is a general revision to the TS sections 3.3.B.3 and 4.3.B.3 in order to:

l. Incorporate administrative changes to present RSCS and RWM surveillance requirements in a more orderly fashion, and to clarify the limiting condition for operation (LCO) existent with the RWM inoperable (as requested by the NRC letter to TVA from J. M. Taylor, dated August 5, 1985).

2. Achieve consistency between units.

3. Adopt Standard Technical Specification requirements for RSCS and RWM operability.

~ ~

Justification of Chan es The RWM and RSCS are monitoring systems which ensure that the reactor operator adheres to a predetermined sequence of control rod withdrawals or insertions when the reactor is operating at low power levels. The rod withdrawal and insert sequence (insertions are made in a reverse order of withdrawals) is designed to limit the worth of any single control rod so that a postulated rod drop accident will not result in peak fuel enthalpies greater than 280 calories/gram.

l. Administrative Changes The proposed revision to section 3.3.B.3.a of units 1 and 3 is purely administrative in nature to correct a sentence grammatically and to re-number a section. The proposed revision to section 3.3.B.3.b is administrative because it clarifies the LCO with the RWM inoperable.

This clarification is consistent with the wording found in Standard Technical Specifications.

2. Changes to Achieve Consistency Between Units The proposed revision to section 3.3.B.3.a of the unit 2 TS will allow suspension of RSCS constraints for individual rods to allow special criticality testing and scram timing, provided that the RWM remains operable. This is consistent with the LCO for units 1 and 3, and ensures that an automatic constraint on control rod patterns remains in place at low power conditions when RSCS constraints are reduced. The scram timing provision is already allowed by Technical Specification 4.3.C.1 and the criticality test provision is supported by the safety evaluation report for Amendment No. 76 to the BFN unit 1 TS.

3. Changes to Adopt Standard Technical Specification Requirements The proposed revision to section 4.3.B.3.a and 4.3.B.3.b affects the startup and shutdown surveillance requirements for RSCS and RWM. These proposed requirements will demonstrate that each function of RSCS and RWM is operable. prior to when that function is required to enforce rod movement constraints, hence ensuring system operability, The RSCS surveillance requirements prior to a reactor startup of (1) a comparator check that meets the same intent as the will'onsist current TS requirements to ensure operability of the group notch circuitry, (2) testing the sequence mode by attempting to withdraw an out-of-sequence rod "after the first in-sequence rod move has been made, and (3) attempting, to move a control rod beyond allowable group notch limits when the group notch mode is automatically initiated to test the operability of the group notch mode. The first testing requirement has not changed in intent and has only been reworded to meet Standard Technical Specification format. The second testing requirement is less extensive than current TS because it only demonstrates the capability of the sequence being used to apply a rod block to another sequence. The proposed requirement is consistent with Standard Technical Specifications and has therefore been found to be acceptable by NRC. The third test requirement is in addition to current TS requirements and is consistent with Standard Technical Specifications.

The RSCS surveillance reauir..oments for roactor shutdorm will consist of (1) a comp rator chock that meets the samo intent as thc cuxr..ent TS reguiromcnts to ensure operability of the group notch circuitry, (2) attempting to move a control rod beyond tho gxoup notch limit" when the group notch nodo i" autonLatically initiated to tost the operability of the group notch mode, and (3) testing tho sequence mode by attempting to insort an out-of-segucnce control rod after the fir t in-sequence rod is inserted during the seguence mode. The fixst testing reguirement has not changed in intent and has only been reworded to moet Standard Tcchnical Specification (STS) fornat. The second testing rcguirement is in addition to cuxxcnt TS requirements and is consistent with STS. Thc third testing r;equircment appears less eztensive than the reguirement as written in the current TS. The proposed testing roquirement .is consistent "!ith STS and the curxent testing xeguirement cannot be performed as written. Therefore, tho proposed testing reguirement constitutos an improvement in safety.

Tho RLJH suz'vcillancc requirement" prior to a reactor staxtup r!ill consist of (1) checking the input data to the RID! computer, (2) verifying that selection of one out-of-segucncc contxol rod will generate a select error, and (3) moving an out-of-seguence control rod to demonstrate rod bloc}: capability. The first requirement has adopted STS rrording to avoid confusion on how to interpret the requirement. :.iisintor.pretation of this xoguirement has resulted in enfor.cement action in the past. The second and third rcguixernents meet the intent of the existing TS. The proposed wording of these rcguixemcnts is con istcnt with STS with c:;coption of the third, which is worded to accommodate allowable insort and withdra':!

errors and altcxnate withdra':! limits. Tire rcguiremcnt of current TS to pcx'form tire Rr;.'i'I computer on-line diagnostic tos t i" being eliminated in order to aciriovc consi tency with STS which do not reauirc such a test.

Because the actual blocking functions r, R'Hii are i>eing to .ted, the capability of tho RHil to perform it" safety functio. i" ad guatcly domon tratod without the on-line diagnostic.

The Rbr! sur.veillance requirements for a reactor irutdown will consi -t of (1) checking tho input data to the PhiH computer, (2) verifying that selection of ono out-of-scquenco control rod r!ill gcncrato a select error, and (3) noving an out-of-seauence control rod to denonstratc x od block capability. The first rcauixemcnt has doptod STS :!ording to avoid confusion on how to inter prot tho reauixcment. !!i -interpretation of thi" rcauiremcnt ha" resulted ir. enforcement action in the past. Tho second requirement meets the ntcnt oi the c:;isting TS and the proposed r!ording i" consi"tent with STS. The third requirement is in addition to thc current TS and i" consist-nt with STS with thc ezccption that it accomodatcs allowable insect and withdraw er ors and alternate insert linits Thc cuxront rcguirement to pcr: orm thc R(ref computer on-linc diagnostic tost is being doletod and i" justified above. Tho current requirement of 4.3.0.3.b.5 to verify proper rod group latching insert error annunciation is being elininated because the noed for the and o tests is obviated by thc proposed now xeauir.cmonts.

03860

. ENCLOSURE 3 Determination of No Significant Hazards Consideration Browns Ferry Nuclear Plant (BFN)

Units 1, 2,. and 3 Descri tion of Amendment Re uest The proposed amendments to BFN units 1, 2, and 3 technical specifications (TS) would be a general revision to the sections covering limiting conditions for operation and surveillance requirements for the'Rod Worth Minimizer (RWM) and the Rod Sequence Control System (RSCS). These changes are proposed t'o make BFN TS consistent with Standard Technical Specifications (NUREG 0123) in the area of control rod pattern constraints under low power conditions.

Specific changes involve:

1. Surveillance testing requirements for RWM and RSCS are being changed to require more suitable tests to ensure system operability.

2. A limiting condition for operation (LCO) which serves no safety function is being deleted.

3. Actions required when RWM is inoperable are being clarified.

4. The action required when sufficient rod pattern controls are not operable is being changed to an action which is more appropriate for the conditions.

The proposed amendment to BFN unit 2 TS would add a provision for bypassing RSCS constraints for individual control rods for the purpose of certain tests.

Basis for Pro osed No Si nificant Hazards Consideration Determination The RWM and RSCS are systems which constrain control,rod patterns under conditions of low reactor thermal power. The design basis of both systems is to mitigate the affects of a control rod drop accident by limiting the peak fuel pellet enthalpy in such an event to less than 280 calories/gram.

1. The proposed revisions to the surveillance requirements will adopt the Standard Technical Specification testing requirements. Because the actual system functions remain unchanged and the operability and testing requirements are consistent with NRC guidance, there is no increase in the consequences of the previously analyzed rod drop accident. These revisions do not create the possibility of an accident or malfunction of any different type, since the system will have the same function as before and the worst case accident under these conditions has been analyzed. There is no reduction in the margin of safety as defined in the basis of the TS since the RWM and RSCS will still restrict peak fuel pellet enthalpy to less than 280 calories/gram in the event of a rod drop accident.

ENCLOSURE.3 (continued)

2. The LCO being deleted required that no rod movement be permitted after testing RSCS restraints while shutting down and before reaching, the RSCS enforcing, region. This is not consistent with the proposed testing requirements, since they will test RSCS restraints after the enforcing region is reached. Because all restraints necessary for RSCS to perform its function are unchanged, the probability or consequences of any previously analyzed accident is not increased. Plant procedure in shutting down will not be changed in that RSCS restraints will control rod movement when required, so that no unanalyzed accident possibility is introduced. Finally, since RSCS system operation is unchanged, no margin to safety as defined in the bases for the TS is reduced.

3. The actions required when RWM is inoperable are being reworded to make clear when a second person verification may substitute for RWM control.

This is unchanged in intent from the current LCO and so does not increase the probability or consequences of any previously analyzed accident.

Since no change in plant configuration or procedure will occur, no unanalyzed accident condition is introduced. Because RWM functions are not being changed, no margin to safety as described in the bases of the TS is reduced.

4. The action required when sufficient rod pattern controls are not present is being changed to allow complete suspension of rod movement as an acceptable alternative to immediately shutting down the reactor. This change will not affect the probability or consequences of any previously analyzed accident. By not allowing rod movement after rod pattern controls are lost, no rod pattern may be generated which results in any new, unanalyzed accident. Finally, since no unanalyzed situation may develope, no margin to safety as described in the basis for the TS is reduced.

Based on these findings, it is proposed to determine that this license amendment request involves no significant hazards consideration.

The proposed revision to what is currently section 3.3.B.3.b will delete a limiting condition for operation (LCO) which relates to the RSCS. This LCO currently requires that no control rod movement be allowed after testing RSCS restraints and before reaching the RSCS enforcing region, and that alignment of rod groups be done prior to performing surveillance tests. These requirements do not appear to serve a purpose for two reasons.

1. Rod alignment must be achieved prior to initiation of RSCS restraints in order to avoid total inability to move control rods.

2. Most of the RSCS shutdown checks in the proposed amendment are to be done after the RSCS is enforcing.

Based on these findings, and because deletion of the LCO is consistent with NRC guidance as found in the Standard Technical Specifications, removal of this LCO is judged to be acceptable from a safety analysis viewpoint.

The proposed revision to what is currently section 3.3.B.3.d will change the LCO which applies when either both RWM and RSCS are inoperable, or when RWM is inoperable and a second licensed operator is not available to verify that the RWM sequence is adhered to. Under the proposed LCO, allowing no control rod movement becomes an acceptable alternative to immediately actuating the manual scram or placing the reactor mode switch in the shutdown position. In the event that all automatic constraints on control rod movement are lost, simply prohibiting subsequent control rod movement will ensure that rod patterns which result in high control rod worths cannot be generated, hence fulfilling the intended function of the RWM and the RSCS. Based on these findings, and because this proposed LCO is consistent with NRC guidance as found in the Standard Technical Specifications, this revision is -acceptable from a safety analysis viewpoint.