Text

Draft Proposed Tech Spec Pages Re Amend to License NPF-43 to Include Provisions for Enabling Oscillation Power Range Monitor (OPRM) Upscale Function in Average Power Range Monitor (APRM)
	ML20210J164
Person / Time
Site:	Fermi
Issue date:	07/30/1999
From:	; DETROIT EDISON CO.
To:	;
Shared Package
ML20210J153	List: ML20210J164; NRC-99-0048, Application for Amend to License NPF-43 to Change TS to Include Provisions for Enabling Oscillation Power Range Monitor (OPRM) Upscale Function in Average Power Range Monitor (Aprm).Draft TS Pages Encl;
References
	NUDOCS 9908040216
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Enclosure 3 to NRC-99-0048 Page 2 1

ENCLOSURE 3 PROPOSED TECIINICAL SPECIFICATION MARKED UP PAGES INCLUDED PAGE(Sh 3.3-1 3.3-1(i) 3.3-3

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3.3 7

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3.3-9

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3.4-1 3.4-2 3.4-3 B 3.3.1.1-7

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l B 3.3.1.1-11

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B 3.3.1.1-21 B 3.3.1.1-22 B 3.3.1.1-23 B 3.3.1.1-24 B 3.3.1.1-25

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B 3.4.1-2 l B 3.4.1-4 B 3.4.1-6 B 3.4.1-7 B 3.4.1-8 B 3.4.1-9 B 3.4.1-10 P

1 RPS Instrumentation 3.3.1.1 3.3 INSTRUMENTATION ,,

3.3.1.1 Reactor Protection System (RPS) Instrumentation LCO 3.3.1.1 The RPS instrumentation for each Function in Table 3.3.1.1-1 shall be OPERABLE.

APPLICABILITY: According to Table 3.3.1.1 1.

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ACTIONS

..................................... NOTE------------ \

Separate Condition entry is allowed for each channel.

CONDITION l REQUIRED [0N COMPLETION TIME A. One or more required A.1 Plac a in 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months channels inoperable. trip.

A. -

NOTE - -

Jo applicable for unct1 ns 2.a. 2.b.

2.c.

)

l 2. dga nd2.f. .

J

........... 7 ..

Plate associated trip 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months system in trip.

(continued)

FERMI UNIT 2 3,3 1 Revision 2. 01/18/99

RPS Instrumentation 3.3.1.1 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIFI S. ...- --- NOTE -

B.1 Place channel in one 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months Not applicable for trip system in trip.

Functi s 2.a. 2.b.

l 2.c. .

avd2.0) @

B.2 Place one trip system 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months One or more Functions in trip.

with one or more recuired channels inoperable in both trip systems.

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l I FERMI UNIT 2 3,3 1(i) Revision 2. 01/18/99

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RPS Instrumentation 3.3.1.1 ACTIONS (continued) l CONDITION -

REQUIRED ACTION COMPLETION TIME H. As required by H.1 Isolate all main 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months Required Action D.1 steam lines.

and referenced in Table 3.3.1.1-1. OR 1

H.2 Be in MODE 3. 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months I. As required by I.1 Initiate action to Immediately '

Required Action D.1 fully insert all and referenced in insertable control Table 3.3.1.1 1. rods in core cells containing or u more fuel lies.

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~RMI UNIT 2 3.3 3 Revision 0 04/03/98

Insert A J. As required by J.1 Initiate alternate 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months Required Action D.1 method to detect and referenced in and suppress Table 3.3.1.1 1. thermal hydraulic instability oscillations.

AND

... .. .. .NOT E- .-.--

LCO 3.0.4 is not applicable.

J.2 Restore required 120 days channels to OPERABLE.

K. Required Action and K.1 Reduce THERMAL 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months associated POWER to <25%

Completian Time of RTP, Condition J not met.-

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1 RPS Instrumentation ,

3.3.1.1 l l

SURVEILLANCE REOUIREMENTS (continued)

SURVEILLANCE FREQUENCY SR 3.3.1.1.16 Verify Turbine Stop Valve-Closure and 18 months !

Turbine Control Valve Fast Closure Functions are not bypassed when THERMAL POWER is = 30% RTP.

SR 3.3.1.1.17 - -- --- -......N0TES . - .. .-- -.- -

1. Neutron detectors are excluded.

2. For Functions 3 and 4 channel sensor response times are not require to be measured.

3. For Function 5 n* equals h els for the purpose of deter in~ng STAGGERED TEST BASIS F e y.

Verify the RPS RESPONSE within 18 months on a limits. STAGGERED TEST BASIS r ^7em 7

5R 3.3.1.1,18 .............. .N t...................

Neutron detector re excluded.

Perform CHANNEL CALIBRATION. 24 months 3R 3.3.1.1.19 Perform LOGIC SYSTEM FUNCTIONAL TEST. 24 months

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n FERMI UNIT 2 3.3 7 Revision 2 01/18/99

Insert il SR 3.3.1.1.20 Venfy OPRM is not bypassed when APRM 24 months Simulated Thermal Power is > 28% and recirculation drive flow is <60% of rated recirculation drive flow.

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I RPS Instrumentation 3.3.1.1 Table 3.3.1.1 1 (page 2 of 3)

Reactor Prattetion System Instrumentation '

APPLICABLE CONDITIONS MODES OR REQUIRID REERENCED OTER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SGtVEILLANCE ALLDWABLE FUNCTION CONDITIONS SYSTEM ACTION D.1 REQUIREENTS VALUE

2. Average Pcuer Range Monitors (continued)

c. heutron 3(C)

Flux - Upscale 1 F SR 3.3.1.1.2 s 120r RTP SR 3.3.1.1.3 SR 3.3.1.1.8 SR 3.3.1.1.12 SR 3.3.1.1.18

c. Inop 1.2 3(C) G SR 3.3.1.1.12 hA

e. 2 out of 4 voter 1.2 2 G 3.3.1.1.2 NA 3.3.1.1.12 g < 3.3.1.1.17 3.3.1.1.19 3 Reactor $esselSteam 1.2 2 G .1'1.1 Dome Pressure - Hign . s 1113 psig SR .3.1.1.9 SR 3.3.1.1.10 SR 3.3.1.1.14 I SR 3.3.1.1.15 SR 3.3.1.1.17 4

keacto* Vessel Water 1.2 2 SR 3.3.1.1.1 Level - Low. Level 3 a 171.9 inenes SR 3.3.1.1.9 SR 3.3.1.1.10 SR 3.3.1.1.14 SR 3.3.1.1.15 SR 3.3.1.1.17 i " sin Steam Isolation 1 F SR 3.3.1.1.9 walve - Closure s 121 closec SR 3.3.1.1.14 SR 3.3.1.1.15 SR 3.3.1.1.17 6 =ain Steam Line 1.; 2 Aaciation - Hign H SR 3.3.1.1.1 s 3.6 I full SR 3.3.1.1.9 mr SR 3.3.1.1.14 backgroteld SR 3.3.1.1.15 i

' 0 -1' Geessure - Hign 1; ;

j G SR 3.3.1.1.1 s 1.88 psig 2 3.3.1.1.9 s SR 3.3.1.1.10 ,

SR 3.3.1.1.14 SR 3.3.1.1.15 (centinvec)

Iac" APD' cnannel provioes inputs te Dotn trip srstems.

C. \

FERM: UNIT 2 3.3 9 Revision 2. 01/18/99 l

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Insert C

f. OPRM Upscale 225% 3'd J SR 3.3.1.1.2 NA J RTP SR 3.3.1.1.8 SR 3.3.1.1.12 SR 3.3.1.1.18 SR 3.3.1.1.20 i

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I Recirculation Loops Operating 3.4.1 i 3.4 REACTOR COOLANT SYSTEM (RCS) 3.4.1 Recirculation Loops Operating LCO 3.4.1 '

I _ ea rc sh no exhibit e ther hyd uli d in abi 'ty ope he "Scr or " R s.

J

a. Two recirculation locas with matched recirculation loop jet pump flows shall )e in operation:

dd 2 One recirculation loop may be in operation provided:

1. LC0 3.3.1.1. " Reactor Prot ion System (RPS)

Instrumentation." Functi .b (Average Power Range Monitors Simulated Ther 1 wer-Upscale) Allowable Value of Table 3.3.1. is s t for single loop operation, when in E : an

2. THERMAL POWER is 67. TP.

Required allowable ation for single loop operation and THE I R' imitation may be delayed for up to 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months aft from two recirculation loop operations to culation loop operation.

APPLICABILITY: MODES 1 and 2.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. Recirculation jet pump A.1 Declare recirculation 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months loop flow mismatch not loop with lower flow:

within limits. "not in operation."

(continoed) l l

FERMI UNIT 2 !

3.4-1 Revision 10. 07/09/99 l J

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Recirculation Loops Operating 3.4.1 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIMI Readorcareoperating l

-l .....! NOTE-he "EyAt Region. festart an idle [

/ recircu)tionloopAr p

/1n / '

/

resett' g a recipfulati g

_ /

/ '

/ / '

flow imiter i not al wed. &L B. Ini iate a ion to Immedia* ly I 1 aert Co rol rods

. incre e core fl w to rest e operati n

/ outsid the "Exi

/

Regio . g

/\ I gd tJo recirculation loops coeratin Be in M

gfplyly yf@ @3 e [i % i gt,@

0. 40r[ circ ation ocefa:1n while ops jd.1 / reactor Im._diately ,

E 1.

j t , sw/tch in

ie /

/ p e n n posit n. /

{ f.: / '

/ / '

/

! Re ::or to e opera: 1ng if :ne - ram Re;1on /

/

,/

[.

/r.: / I l" l I., '

/

,/

Cxettnermal hycrau]1e insIaD111:y evicentec. '

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m m- I FE ".! UrJIT 2 3.4 2 Revision 2. 01/18/99

l Recirculation Loops Operating 3.4.1 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY

$ .4.1.1 ..................wE/...............

On1 required o be per ormed en del' op .ating in he ".ta ility areness" glon.

/

Verify he reac r core not exht iting / 1houj

( core t. ermal h draulic i stability'.

5;. 3.4.1 ........ . .

.N0TE............-......

Not required to be performed until hours after both recirculation loops ar operation.

Verify recirculation loop 'et p flow 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mismatch with both recirc

ion ops in operation 15:

a. 5 10% of rated r fl when operating at c 7 ated core flow; and D. : 5: of rat c e flow wnen operating at e 70: of .

c core flow.

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E R."! UNIT 2 3.4 3 Revision 2 01/18/99 1 L I

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RPS Instrumentation B 3.3.1.1 i

BASES l

{

APPLICABLE SAFETY ANALYSES. LCO, and APPLICABILITY (continued) i 1

Averaoe Power Ranoe Monitor l The APRM channels provide the primary indication of neutron flux within the core and respond almost instantaneously to neutron flux increases. The APRM channels receive input i

- signals from the local power range monitors (LPRMS) within '

the reactor core to provide an indication of the power distribution and local power changes. The APRM channels average these LPRM signals to provide a continuous i

indication of average reactor power from a few percent to l

greater than RTP.3 M The APRM System is divided into 4 PRM channels and 4 2-out-of 4 voter channels. Each APRM c el provides inputs to each of the four voter channels four voter channels are divided into two groups of tw ac with 4th providing inputs to one RPS designed to allow one APRM 3 sy each group of two

. The APRM System is ,p p s

to be bypassed. A trip from el ,

t no voter channels.

one unbypassed APRM will 9+p i

result in a " half trip' all ur vo .:hannels. but no l

trip inputs to either RP 6 ystem. 1p from any two unbypassed APRM chi Tresult i s full-trip in each of the four voterA el which in turn results in two trip inputs into ea rip logic channel (Al, A2 Bl.

}

T#yt F and B2). AThre voter cnann are ur APRM channels and all four of the single failur ired to be OPERABLE to ensure that no ill precitMe a scram on a valid signal. In addition. to p adecuate coverage of the entire core.

consistent witn e cesign bases for APRM Functions 2.a.

2.b. and 2.c. at least 20 LPRM inputs, with at least three l

LPRM inputs from each of the four axial levels at which the LPRMS are located. are recu1 red for each APRM channel. 9

'JP# 2.a Averaoe Power Rance Monitor Neutrnn Flux-Voscaja (Setoown)

For operation at low power (i.e.. MODE 2), the Average Power Range Monitor Neutron Flux-Upscale (Setdown) function is capable of generating a trip signal that prevents fuel damage resulting from abnormal operating transients in this power range. For most operation at low power levels, the Average Power Range Monitor Neutron Flux-Upscale (Setcown)

Function will provide a secondary scram to the Intermediate Range Monitor Neutron Flux-High Function because of the relative setpoints. With the IPfis at Range 9 or 10. it is possible that the Average Power Range Monitor Neutron FERMI UNIT 2 B 3.3.1.1 - 7 Revision 2 01/18/99

Insert D Each APRM also includes an Oscillation Power Range Monitor (OPRM) Upscale Function which monitors small groups of LPRM signals to detect thermal-hydraulic instabilities.

Insert E APRM trip functions 2.a,2.b,2.c, and 2.d are voted independently from OPRM Upscale Function 2.f. Therefore, any Function 2.a,2.b,2.c, or 2.d Insert F Similarly, a Function 2.f trip from any two unbypassed APRM channels will result in a full trip from each of the four voter channels.

Insert G For the OPRM Upscale Function 2.f. LPRMs are assigned to cells of 4 detectors, with a total of 30 cells assigned to each APRM channel. A minimum of 21 cells per channel, each with a minimum of 2 LPRMs per cell, must be OPERABLE for the OPRM Upscale Function 2.f to be OPERABLE. The OPRM Upscale Trip Setpoint limits are calculated in accordance with methodologies outlined in Reference 16.

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RPS Instrumentation B 3.3.1.1 BASES APPLICABLE SAFETY ANALYSES. LCO. and APPLICABILITY (continued) 2.d. Averaoe Power Ranoe Monitor-Inoo This Function provides assurance that a minimum number of APRMs are OPERABLE. For any APRM channel, any time: 1) its mode switch is in any position other than 'OPER": 2) there

-- is a loss of input power: 3) the automatic self test system detects a critical fault with the APRM channel: or 4) the firmware/ software watchdog timer has timed out, an Inop trip signal is sent to all four voter channels. Inop trips from two or more unbypassed APRM channels result in a trip output from all four voter channels to their associated trip system. This Function was not specifically credited in the accident analysis, but it is retai d for the overall redundancy and diversity of the R s required by the NRC approved licensing basis.

There is no Allowable Value r this nction.

This function is required to OPERABLE in the MODES where the APRM Functions are r ire 2.e. 2 out of 4 Vot tO e 2 out of 4 Vote I g the APRM Func such, it is n

on provides the interface between e final RPS trip system logic. As ir t be OPERABLE in the MODES where the APRM Functions quired and is necessary to support tne safety analysis icable to each of those Functions.

Therefore. the 2 ut of 4 Voter Function is required to be OPERABLE in MODES I and 2.

Both voter channels in each trip system (all four voter cnannels) are reou1 red to be OPERAELE. Eacn voter channel also inciuoes seif diagnostic functions. If any voter channel detects a critical fault in its own processing, an Inop trip is issueo from that voter channel to the associated trip system.

I W AS There is no Allowable Value for this Function.

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FERMI UNIT 2 i B 3.3.1.1 - 11 Revision 2 01/18/99 l l

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Insert H 1

, including the OPRM Upscale Function, i In*rt I The 2-out-of-4 Voter Function votes APRM Functions 2.a. 2.b,2.c, and 2.d independently of Function 2.f. The voter also includes separate outputs to RPS for the two independently voted sets of Functions, each of which is redundant (four total outputs). The voter Function 2.e must be declared inoperable if any ofits functionality is inoperable. However, due to the independent voting of APRM trips, and the redundancy of outputs, there may be conditions where the voter Function 2.e is inoperable, but trip capability for one or more of the other APRM Functions through that voter is still maintained. This may be considered when determining the condition of other APRM Functions resulting from partial inoperability of the Voter Function 2.e.

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Insert J 2.f. Oscillation Power Rance Monitor (OPRM) Upscale The OPRM Upscale Function provides compliance with GDC 10 and GDC 12, thereby providing protection from exceeding the fuel MCPR safety limit !

(SL) due to anticipated thermal-hydraulic power oscillations. !

References 14,15, and 16 describe three algorithms for detecting thermal-hydraulic instability related neutron flux oscillations: the period based detection algorithm, the amplitude based algorithm, and the growth rate based algorithm. All three are implemented in the OPRM Upscale Function, but the safety analysis takes credit only for the period based detection algorithm. The i remaining algorithms provide defense in depth and additional protection l against unanticipated oscillations. OPRM Upscale Function OPERABILITY l for Technical Specification purposes is based only on the period based l detection algorithm. ;

The OPRM Upscale Function receives input signals from the local power range monitors (LPRMs) within the reactor core, which are combined into cells for evaluation by the OPRM algorithms.

The OPRM Upscale Function is required to be OPERABLE when the plant is at 225% RTP, the region of power-flow operation where anticipated events could lead to thermal-hydraulic instability and related neutron flux oscillations. Within this region, the automatic trip is enabled when THERMAL POWER, as indicated by the APRM Simulated Thermal Power, is 228% RTP and recirculation drive flow is <60% of rated flow, the operating region where actual thermal-hydraulic oscillations may occur. The lower bound,25% RTP, is chosen to provide margin in the unlikely event of a power increase transient that could occur without operator action while the plant is operating below the 28% automatic OPRM Upscale trip enable point.

An OPRM Upscale trip function trip is issued from an APRM channel when the period based detection algorithm in that channel detects oscillatory changes in the neutron flux, indicated by the combined signals of the LPRM detectors in a cell, with the period confirmations and relative cell amplitude exceeding specified setpoints. One or more cells in a channel exceeding the trip conditions will result in a channel trip. An OPRM Upscale trip is also issued from the channel if either the growth rate or amplitude based algorithms detect growing oscillatory changes in the neutron flux for one or more cells in that channel.

Three of the four channels are required to be operable. Each channel is capable of detecting thermal-hydraulic instabilities, by detecting the related

neutron flux oscillations, and issuing a trip signal before the MCPR SL is exceeded. There is no allowable value for this function. The OPRM Upscale Trip Setpoint limits are calculated in accordance with methodologies outlined in Reference 16.

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I RPS Instrumentation B 3.3.1.1 BASES ACTIONS (continued)

A.1 and A.2 M Because of the diversity of sen rs available to provide trip signals and the redundan of the RPS design, an allowable out of service ti of 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months has been shown to l be acceptable (Refs. 9@ to permit restoration of any inoperable channel to OP; status. However, this out of service time is only acceptable provided the associated Function's inoperable channel is in one trip system and the Function still maintains RPS trip capability (refer to Required Actions B.1. B.2 and C.2 Bases). If the inoperable channel cannot be restored to OPERABLE status within the allowable out of servic time, the channel or the associated trip system must be pl in the tripped condition per Required Actions . and A.2. Placing the inoperable channel in trip (or e sociated trip system in trip) would conservatively nsa or the inoperability, restore capability to acco a ingle failure, and i allow operation to continue. Iternatively, if it is not desired to place the cha 1( rip system) in trip (e.g..

as in the case where pla inoperable channel in trip would result in a f and its Required i sc m). Condition D must be entered ta n.

Q g 2,7 As noted. Reg n_A.2 s not applicable for APRM l Functions 2. .b . .Gf>dMA Inoperability of one required APRM n affects both trip systems: thus.

Required Action must be satisfied. This is the only action (other th restoring OPERABILITY) that will restore capal:ility to accommodate a single failure. Inoperability of more than one recuired APRM channel of the same trip function results in loss of trip capability and entry into Concition C. as well as entry into Condition A for each channel.

B.1 and B.2 Condition B exists when, for any one or more Functions at least one recu1 rec channel 1s inoperable in each trip system. In tnis condition. provided at least one channel per trip system is OPERABLE. the RPS still maintains trip caDability for that Function. but cannot accommodate a single failure in either trip system.

Required Actions B.1 and B.2 limit the time the RPS scram logic, for any Function, would not accommodate single FERMI UNIT 2 B 3.3.1.1 - 21 Revision 2 01/18/99

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RPS Instrumentation B 3.3.1.1 BASES l

ACTIONS (continued) failure in both trip systems (e.t].. each trip system remains in a one out of one arrangement for a typical four channel '

Function). The reduced reliability of this logic arrangement was not evaluated in References 9 and 13 for the 12 hour1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months Completion Time. Within the 6 hour6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months allowance. the associated Function will have all required channels OPERABLE or in trip (or any combination) in one trip system.

Completing one of these Required Actions restores RPS to a reliability level equivalent to that evaluated in References 9 and 13. which justified a 12 hour1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months allowable out of service time as presented in Condition A. The trip system in the more degraded state should be placed in trip or, alternatively, all the inoper channels in that trip system should be placed in trip .. a trip system with two inoperable channels could i more degraded state than a trip system with four n per channels if the two inoperable channels are in me nction while the four inoperable channels are all i ifferent Functions). The decision of which trip s em n the more degraded state should be based on prude nt and take into account current plant condit' s .e , what NODE the plant is in).

If this action wouh r ul in a scram, it is permissible to place the other trip or its inoperable channels in trip.

The 6 hour6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months C Time is judged acceptable based on the remaining capab to trip, the diversity of the sensors available to pro e the trip signals. the low probability of extensive numbers of inoperabilities affecting all diverse Functions, and the low probability of an event requiring tne initiation of a scram.

Alternately. if it is not desired to place the inoperable channels (or one trip system) in trip (e.g., as in the case where placing tne inoperable channel or associated trip system in trip would result in a scram). Condition D must be entered and its Recu1 red Action taken. _

2. d , a nd 2.. +'. )

As noted. Condition is~not applicable for APRM Functions l 2.a. 2.b. 2.c CvfqNc0 Inoperability of an APRM channel affects both trip systems and is not associated with a specific tr1D system as are the APRM 2 out of 4 voter and i other non APRM channels for which Condition B applies. For an inoperable APRM channel. Recuired Action A.1 must be satisfied, ano 1s the only action (other than restoring l 1

l FERMI UNIT 2 B 3.3.1.1 - 22 Revision 2 01/18/99 l l \

RPS Instrumentation B 3.3.1.1 BASES ACTIONS (continued)

(2.d, and 2.TC OPERABILITY) that will restore capability to commodate a single failure. Inoperability of a function n more than y

] one required APRM channel results in loss of rip capability and entry into Condition C as well as entr into Condition b forN4 l A for each channel. Because Conditions A d C provide

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Required Actions that are appropriate for the inoperability IfuncO*8) l of APRM Functions 2.a. 2.b. 2.c.Of#Er.Asnd these Functions are not associated with specific trip systems as h are the APRM Condition 2 out B does notofapply.

4 voter and other non APRM channels.

L.1 Required Action C.1 is intended t ensure that appropriate actions are taken if multiple. o able, untripped channels within the same trip te or the same Function result in the Function not n inirI"FRPS trip capability.

A Function is considered to b ntahning RPS trip capability when sufficierf cha els are OPERABLE or in trip (or the associated trip s1 in trip). such that both trip systems will gen at m t'p ' signal from the given Function on a valid al r the typical Function with one out of two tak t e gic 6nd the IRH and APRM Functions. this e re both trip systems to have one channel OPE n ip (or the associated trip system in trip). F c o 5 (Main Steam Isolation Valve-Closure). would require both trip systems to have each channel ass ted with the PSIVs in three main steam lines (not necess ily the same main steam lines for both trip systems) OPERABLE or in trip (or the associated trip system in trip).

For Function 8 (Turbine Stop Valve-Closure). this would recuire both trip systems to have three channels, each OPERABLE or in trio (or the associated trip system in trip).

The Completion Time is intended to allow the operator time to evaluate. and repair or place in trip any discovered inoperabilities that result in a loss of RPS trip operability. The I hour Completion Time is acceptable because it minimizes risk wnile allowing time for restoration or tripping of channels.

FERMI UNIT 2 B 3.3.1.1 - 23 Revision 2. 01/18/99

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l RPS Instrumentation l B 3.3.1.1 I i

BASES ACTIONS (continued)

(L1 Required Action D.1 directs entry into the appropriate l Condition referenced in Table 3.3.1.11. The applicable Condition specified in the Table is Function and MODE or other specified condition dependent and may change as the Required Action of a previous Condition is completed. Each time an inoperable channel has not met any Required Action of Condition A. B. or C and the associated Completion Time l has expired. Condition D will be entered for that channel i and provioes for transfer to the appropriate subsequent i Condition, g,g }

I

' E.1.F.1.G.I.H.I.((M)H.2A w

If the channel (s) is not res"Ad t FERABLE status or placed in trip (or the assod tr 5. system placed in trip) within the allowed Co on Time, the plant must be placed in a MODE or oth epe d condition in which the LCO does not apply. Alt . fcr Condition H, the associated MSLs may i (Required Action H.1). and. '

if allowed (i.e. , ty analysis allows operation with an M5L isola ation with that MSL isolated may continue. Iso g ffected MSL accomplishes the l safety funct' o h Hnoperable channel. The allowed Completion 1 s ar r'easonable, based on operating experience, to 'a the specified condition from full power conditions in an .derly manner and without challenging clant systems. n addition the Completion Time of Required l Acticyf V.lM54 Consistent with the Completion Time provided in LLO 3.2.2. ' MINIMUM CRITICAL POWER RATIO (MCPR)."

Aeltans E.I and K.l ar e}

CERMI UNIT 2 B 3.3.1.1 - 24 Revision 2 01/18/99

RPS Instrumentation B 3.3.1.1 BASES ACTIONS (continued)

L.1 If the channel (s) is not restored to OPERABLE status or placed in trip (or the associated trip system placed in trip) within the allowed Completion Time, the plant must be

- placed in a H0DE or other specified condition in which the LC0 does not apply. This is done by immediately initiating action to fully insert all insertable control rods in core cells containing one or more fuel assemblies. Control rods in core cells containing no fuel assemblies do not affect the reactivity of the core and are, therefore, not required to be inserted. Action must continue until all insertable control rods in core cells contain' g one or more fuel W{ /, y assemblies are fully inserted.

SURVEILLANCE As noted at the beginning o REQUIREMENTS SR the Srs for each RPS instrumentation Functio are I ated in the SRs column of Table 3.3.1.1 1.

The Surveillances d ie by a Note to indicate that when a channel is di an inoperable status solely for performance of r '

veillances. entry into associated Conditions an 'r Actions may be delayed for up to 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months , pro ed ssociated Function maintains RPS trip capability, t case of the APRM Functions 2.a. 2.b.

2.c. and 2.d. R ip capability is maintained with any two

' OPERABLE APRMs r 31ning. Upon completion of the Surveillance or expiration of the 6 hour6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months allowance, the l channel must be returned to OPERABLE status or the applicable Condition entered and Required Actions taken.

This Note is based on the reliability analysis (Ref. 9) assumption of the average time required to perform cnannel Surveillance. That analysis demonstrated that the 6 hour6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months testing allowance aces not significantly reduce the probability that the RPS will trip when necessary.

SR

?.3.1.1.1 and SR 3 3.1.1.2 Performance of the CHANNEL CHECK once every 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and once every 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months ensures that a gross failure of instrumentation has not occurred. A CHANNEL CHECK is normally a comparison of the parameter indicated on one channel to a similar parameter on other channels. It is based on the assumption that instrument channels monitoring FERMI UNIT 2 B 3.3.1.1 - 25 Revision 2. 01/18/99

1 i

Insert K L1 If OPRM Upscale trip capability is not maintained, Condition J exists. References 13 and 17 justified use of alternate methods to detect and suppress oscillations for a limited period of time. The alternate methods are procedurally established consistent with the guidelines identified in References 18 and 19 requiring manual operator action to scram the plant if certain predefined events occur. The 12 hour1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months allowed action time is based on engineering judgment to allow orderly transition to the alternate methods while limiting the period of time during which no automatic or alternate detect and suppress trip capability is formally in place. Based on the small probability of an instability event occurring at all, the 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months is judged to be !

reasonable.

L2 The alternate method to detect and suppress oscillations implemented in accordance with J.1 was evaluated (References 13 and 17) based on use up to 120 days only.

The evaluation, based on engineering judgment, concluded that the likelihood of an instability event that could not be adequately handled by the alternate methods during j this 120 day period was negligibly small. The 120 day period is intended to be an {

outside limit to allow for the case where design changes or extensive analysis might be required to understand or correct some unanticipated characteristic of the instability detection algorithms or equipment. This action is not intended and was not evaluated as a routine alternative to returning failed or inoperable equipment to OPERABLE status. Correction of routine equipment failure or inoperability is expected to normally be accomplished within the completion times allowed for Actions for Condition A.

A note is provided to indicate that LCO 3.0.4 is not applicable. The intent of that note is to allow plant startup while operating within the 120-day completion time for action J.2. The primary purpose of this exclusion is to allow an orderly completion ,

l of design and verification activities without undue impact on plant operation in the event of a required design change to the OPRM function as described in the paragraph above. It is not intended as an alternative to restoring inoperable equipment to OPERABLE status in a timely manner.

I 1

RP5 Instrumentation E 2.3.1.1 EASE 5 1URVEILLANCE REQUIREMENTS (continued)

The Frequency of SR 3.3.1.1.11 is Dased upon a 184 cay calibration interval in the determination of the magnituae of equipment drift in the setpoint analysis. The Freauency of SR 3.3.1.1.14 is based upon = 18 month calioration interval in the determination of the magnitude of eculpment drift in the setpoint analysis.

SR 3.3.1.1.12 A CHANNEL FUNCTIONAL TEST is performed on each reouired channel to ensure that the entire channel will perform :ne intended function. For the APRM Functions, this test supplements the automatic self test functions that coerate continuously in the APRM and voter channels. The APRM CHANNEL FUNCTIONAL TEST covers APRM channels (including for Function 2.b only, the rec' 21ation flow input function. excluding the flow a tier), the 2 out of-4 voter channels, and the in Face ections to the RPS trip systems from the vot nne Any setpoint adjustment shall be consis ith the assumptions of the current plant specifici po methodology. The 184 day Frequency of SR 3.3.1. 's sed on the reliability 1 analysis ofG4/e/eev:. : The actual voting logic of the 2 out of 4 v. .e c a ne s is tested as part of SR 3.3.1.1.19.)

One is ed rf)

For Funct1 .

e that reau1res this SR to be performed in ours of entering MODE 2 from MODE 1 1s prov1aea. Te of the MODE 2 APRM Function cannot De performea in 1 without utili:1ng .)umpers or liftea leaas. This No allows entry into MODE 2 from MODE 1 if the associated Frecuency is not met per SR 3.0.2.

SR 3.3.1.1.15 and SR 3.3 1.1.19 and0F'Rk)

The LOGIC SYSTEM FUNCTIONAL TEST cemonstral es tne OPERABILITY of ine reau1 red tilp logic for Ia specific cnannel. The functional testing of control roas (LCO 3.1.3), ana SDV vent and arain valves :LCO 3.1.3).

overlaos this Surveillance to provice complete testing of the assumed safety function. For the 2-out of-4 Voter l Function. tne L5FT includes simulating APRM trip conal: 1ons at the APRM cnannel inputs to the 2 out of wp trap voter channel to cneck. all comD1 nations of two tripped inouts to the 2 out of-4 trip voter lo~gic in the voter cnannels.

NI2 5 3.3.1.1 - 31 Revision.6. 15/28/99 1

RPS Instrumentation E 3.3.1.1 EASE 5 SURVEILLANCE REQUIREMENTS (continued)

SR 3.3.1.1.18 A CHANNEL CALIBRATION is a complete check of the instrument 1000 and the sensor. This test verifies that the cnannel responds to the measured parameter within the necessary range and accuracy. CHANNEL CALIBRATION leaves the cnannel adjusted to account for instrument drifts between successive calibrations consistent with the plant specific setpoint methodology. For the APRM ~5imulated Thermal Power - Voscale Function, this SR also includes calibrating the associated recirculation loop flow cnannel.

SR 3.3.1.1.18 is modified by a Note that states that neutron detectors are excluded from C L CALIBRATION because they are passive devices. with mini rift. and because of tne difficulty of simulating a me ful signal. Changes in neutron detector sensitivit mpensated for by performing the 7 day calor me ric Hibration(SR3.3.1.1.3) and the 1000 MWD /T LPRM ca tion against the TIPS (SR 3.3.1.1.8).

The Frequency of SR 3. is based upon 24 month y calibration inter in he determination of the magnitude U of equipment or th setpoint analysis.

]

We/ , . -

EFERENCE3 T

1. UFSAR. 4 9ur 7.2 2.

2. UFSAR. Se. ,1on 15.4.1.2.

3.

NED0 23842. " Continuous Control Rod Witnorawal in :ne Startup Range. Aor11 18. 1978.

4 UFSAR. Section 5.2.2.3.

5. UFSAR. Section 15.4.9.

6. UFSAR. Section 6.3.3.

7 UFSAR. Cnacter 15.

3.

P. Chett (NRC) letter to G. Lainas (NRC'. "BWR Scram Distnarge System Safety Evaluation. December 1. 1980.

TERMI UNIT : E 3.3.1.1 - 34 Revision'6. 05/28/99

i E

l I

l Insert L SR 3.3.1.1.20

! This SR ensures that scrams initiated from the OPRM Upscale Function (Function

! 2.f) will not be inadvertently bypassed when THERMAL POWER, as indicated by

the APRM Simulated Thermal Power, is 228% RTP and recirculation drive flow is l ..<60% rated flow. This normally involves confirming the bypass setpoints. The bypass setpoint values are considered to be nominal values as discussed in Reference

.20, and have been adjusted for power uprate. The surveillance ensures that the OPRM Upscale Function is enabled (not bypassed) for the correct values of APRM Simulated Thermal Power and recirculation drive flow.

If any bypass setpoint is nonconservative (i.e., the OPRM Upscale Function is bypassed when APRM Simulated Thermal Power 228% and recirculation drive flow

<60% rated), then the affected channel is considered inoperable fr le OPRM Upscale Function. Alternatively, the bypass setpoint may be adjus. to place the channel in a conservative condition (unbypassed). If placed in the unbypassed condition, this SR is met and the channel is considered OPERABLE.

The Frequency of 24 months is based on engineering judgment and reliability of the components.

l l

l RPS Instrumentation 3 3.3.1.1 EASE 5

EFERENCES (continued)

9. NED0 30851-P A . " Technical Specification Improvement Analyses for SWR Reactor Protection System.

Marcn 1988.

10. UFSAR. Table 7.2-4

11. NEDC 31336. " Class III. October 1986. General Electric 1 Instrument Setpoint Methodology."

12. NE00 32291. " System Analyses for Elimination of Selected Response Time Testing Requirements. January 1994: and Ferm12 SER for Amenoment 111. cated toril

18. 1997.

13. NEDC-32410P A. " Nuclear Mea ment Analysis and Control Power Range Neutrq itor (NUMAC PRNM)

Retrofit Plus 03 tion IIIA a ty Trin Function.

I October 1995.(pod)5uncQ6JmVitA.WW50 s

l l

' E E" dili 2 E 3.3.1.1 - 35 Revision 6. 05/23/99

1 f

f Insert M l 14. NEDO-31960-A, "BWR Owners' Group Long-Term Stability Solutions l

Licensing Methodology," November 1995.

l 15. NEDO-31960-A, Supplement 1, "BWR Owners' Group Long-Term Stability Solutions Licensing Methodology," November 1995.

16. NEDO-32465-A, " Reactor Stability Detect and Suppress Solutions Licensing Basis Methodology for Reload Applications," August 1996.

17. NEDC-32410P-A, Supplement 1, " Nuclear Measurement Analysis and l Control Power Range Neutron Monitor (NUMAC PRNM) Retrofit Plus Option Ill Stability Trip Function," November 1997.

l 18. Letter, L. A. England (BWROG) to M. J. Virgilio, "BWR Owners' Group Guidelines for Stability Interim Corrective Action," June 6,1994,

19. NRC Generic Letter 94-02, "Long-Term Solutions and Upgrade of Interim Operating Recommendations for Thermal 11ydraulic Instabilities in Boiling Water Reactors," July 1994.

20. BWROG Letter 96113, Kevin P. Donovan (BWROG) to L. E. Phillips l

(NRC), " Guidelines for Stability Option III ' Enable Region' (TAC M92882)," dated September 17,1996.

l 1

h

Recirculation Loops Operating B 3.4.1 BASES BACKGROUND (continued) begins to boil, creating steam voids within the fuel channel that continue until the coolant exits the core. Because of reduced moderation, the steam voiding introduces negative reactivity that must be compensated for to maintain or to )

increase reactor power. The recirculation flow control !

system allows operators to increase recirculation flow and sweep some of the voids from the fuel channel, overcoming the negative reactivity void effect. Thus, the reason for having variable recirculation flow is to compensate for reactivity effects of boiling over a wide range of power generation without having to move control rods and disturb oesirable flux patterns.

Each recirculation loop is manual % started from the control room. The MG set provides regu 'on of individual recirculation loop drive flow flow in each loop is manually controlled within i s lished by the recirculation speed contro em.

[GDC of 10 FR 50 dix e f. states that the

( rea or cor and as ocia nt. control and prot tion sy tems s 11 be # ne osur that p er oscil tions ich ca resul i e ee g spe fied f 1 desig imits are no possib e reli ly dete ted and uppressed.

BWR ores t ' cal o ate th the esence f global ux no ' e in y' c le r e whic)(is due o rando boiling f ow noi e. A +

power // low con tions ar,e changed along N1th o* er syst, arame ers (xen n. subco61ing pow r

/ distr but1on./t . ) th thermal- ydraulig/ reactor k netic p fee ack mec,Manism c, be enha ced SUCry/that pert rDations p ma> result /in susta ed limi cycle or/ divergen ycillatJonsinp er and f w. ,

f / '

iwo ma3or modee of oscil tions h e been o erved in BWRs The first moo 1s the f naamenta or core- de oscillatio mooe in wn1 . the enti e core oscillates phase in a o ven axial plan The se nd mode /nvolves r gional oscill clon in which ne nalf o the core / oscillate 180 degrees ut of pnase wifh the oth r half. %tudieshaeindicatedtat acequate acrgin t the SafeAy L1mit M7PR may not e si curing oscillations. /

)

FERMI UNIT 2 B 3.4.1 - 2 Revision 2. 01/18/99

d

)

l

~

Recirculation Loops Operating B 3.4.1 i

BASES l

APPLICABLE SAFETY ANALYSES (continued) her 1 hydr ulic st lity a ysis ( f. 5) s conc de tha proc ures for detect' 9 and su ressin power o illat" ns that ight induced y a the al hy aulic 0 i stabi ity are ecessa to prov 'e reaso able a urance ;

hat t requi ments Referen e 4 are atisfi .

j Recirculation loops operating satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii).

1 LC0 Two recirculation loops are required to be in operation with their flows matched within the limits specified in l SR(KKY.7)to ensure that during caused by a break of e piping of one recirculation the assumptions of the LOCA analysis are satisfied. limits specified in l g Mg \ 4(1/2]notmet,thereci i op with the lower i

f ow must De considered not rat n. With only one recirculation loop in operati difications to the APRM s

Simulated Thermal Power l ca' tpoint (LCO 3.3.1.1) and l a limitation on THERHAL be applied to allow 1 continued operation si ith the assumptions of the safety analysis. }

c F

0p atio tha i ce therm -hydra ic i tabilit a no ermi ed. c ' nally in ord to oid oten al p o 1 ons d to th mal- draulic g ins ilit , op t' n t cer in com nati s of p er - d dF f1 are ot pe e.

r gions re re er ed to asTheee"Scr restr'cted ower an fl m" a " Exit" reg' ns y nd ar defin d by ases Fi ure B .4.1 .

J A Note is provided to allow 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months following the transition to single loop operation from two loop operation to establish the APRM Simulated Thermal Power - Upscale setpoint in accordance with the single loop allowable value, which is specified in Table 3.3.1.11 and to establish i operation at s 67.2% RTP. The 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months period is sufficient to make the adjustments given the relatively small change required. This transition that results in applying the new ;

single loop allowable values to APRM OPERABILITY. is such that any ARPM non compliance with the required allowable ,

value after this 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months allowance results in ACTIONS of LCO 3.3.1.1 being entered: no ACTION of LC0 3.4.1 would apply.

FERMI UNIT 2 -

B 3.4.1 - 4 Revision 10. 07/09/99

Recirculation Loops Operating B 3.4.1 BASES ACTIONS (continted) en eratin in the Exit" r ion (ref to Figur B 3. 1 1). he pot tial for hermal- draulic

/ in abili es is ' creased d suffi ent margi may not be ailabl for o rator re onse to uppress po ential power '

scill ions. herefore action st be ini ated imme ~ately J restore peratio outside o the " Exit" re n. Control rod sertio and/or cor flow incr ases ar desig 'ted as t . means o accompli this ob' ctive. {

Requir Action .1 is mo ified by ate that reclude core low incre es by r start of idle re 'rculati loo , or by re etting recircula n flow miter. ore fl w increas by the e means w not suj, port ti _ly c6mpletion the a ion to re o opert<.1on out ide t

~ Exit" Region. /

u

\t. r l 91 With no recirculat' n lo nFeratidninMOD 2 the

/ plant must be Dr g o ,

in which the LCO does not apply. To achi egh s us, the pitnt must be brought to l MODE 3 within ou this conditi on, the recirculation loops are not 'r to be operating;because of the reduced seve -

2 and minimal dependence on the recirculation [astdown character /lstics. The allowed Completion Tim nours is reasonatlle. based on operating i

l experience. to r '

MODE 3fromMODEf2conditionsinan orderly manner and without challenging plant systems.

'm- A O

/ / / j I.

/

ope ting with recirc

/

tion pum s in oper 1on in h 1 j

00E oropera+/nginthe Scram" rggion (refa to Bases Fig B 3.4.1/1). or if is Aetected.jtnen unac rgsult.

ptable poyer oscill,ions oremay therrgl

/ hydraul'c ins Therefore. t e reactor Jnode switch must be /the JmmediateJfplaced t shutd6wi

' potential for unactestable po/er oscillations. !

/j Thermal -hycraul instabil is evid nced by a.fsustained' i increase in APF.M or LPRM '

or,more time its initia eaktopeaknoiselevelreach2ng2{

level and occurring with a '

ctraracterlst c period of less than 3 secondst ,

FERMI - UNIT 2 B 3.4.1 - 6 Revision 2. 01/18/99 '

1 1

1 l

l Recirculation Loops Operating B 3.4.1 l

BASES ACTIONS (continued) ~

If own entr[nto thi/conditi onsequen 4 of an is an u voidable well ent, earl initiati n of the ,

equi ed Attic is appr riate. 50 it is ecognizet'that dur' g certa' abnorm conditio 5. it ma become i op ational y necess y to ent the " Scram" or ~E t~

~

t/m j r ion for the purp se of: 1 prote g plant uipment.

i f ich if t were fail co d impa lant saf y. or

) prot cting a fety or el oper ing limi . In the .

cases. the app riate ac onsfor/theregio enteredpould{

be p formed required j j Qh e reQuir ents are consist t with Refbr?nces 5 and 6.)

A A

SURVEILLANCE REQUIREMEf!TS kR 3./1.1 i Thi TR pr ides fr uent ic itoring 'or core t rmol-h draulic 'nsta il' mo itoring RM and LP gnals or a su ained rea i APRM or LPRM peak o

/ peak ng, se leve reachin "

e times ts initia level and ocdurring ith r ct i ic peri d of less an 3 I seco s. The 1 h eqt cy 's base on the sma pot tial f core -hypraulic cillations o occur outside the' ~c .. . L ~ Exit ~/ region . Therefor , frequent y[

g monitoring oberating in i

+ne Ri and LPRM sig als is apprporiate wne'n

/* ability Awaren,ess region./

This SR 15 modyf ed by a $ote th/t states pa formance only recuirecinen operating in/the ~StaDil essty Awarey/s~

region (refer :: Eases figure S'3.4.1 1) .e. in Ine power-to flos recion inat is rysar regione of nigne/

ProDability fc core InerW f.ycraulic 1/istabilit/es). ini /

15 acceptaDie Decause outs 1ct the Stab /llity Awareness" / 'l region, power and f }ow cond/tions are guch that/suf ficieng margin exists to tne potent /lal for core therma 7 hycraulit instability to allow rout 1/le core morritoring./ Any / j j unanticipatec entry into Ine ~5: ability f Awargness" rec /on I would recuire ir.meciate verification of core / stability since the Surveillance -cuic npt De current. /

ERMI UNIT 2 E 3. 4.1 - 7 Revision 2. 01/18/99

Recirculation Loops Operating B 3.4.1 BASES SURVEILLNJCE REQUIREFINTS (continued) l SR 3.4.1 This SR ensures the recirculation loops are within the allowable limits for mismatch. At low core flow (i .e. . {

)

< 70% of rated core . flow). the MCPR requirements provide 4 larger margins to the fuel cladding integrity Safety Limit such that the potential adverse effect of early boiling transition during a LOCA is reduced. A larger flow mismatch ,

can therefore be allowed when core flow is < 70% of rated l core flow. The recirculation loop jet pump flow, as used in (

this Surveillance is the summation of the flows from all of {

the jet pumps associated with a single recirculation loop.

]

The mismatch is measured in terms percent of rated core flow. If the flow mismatch exc s the specified limits.

the loop with the lower flow i c idered "not in operation . The SR is not r re n both loops are not in operation since the mis c limi are meaningless during single loop or natura 1 culation operation. The Surveillance must be pe rme thin 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months after both loops are in operation. 2 our Frequency is consistent with the Surveillan Fr e for jet pump OPERABILITY !

verification and en hown by operating experience to '

be adequate to de +

ormal jet pump loop flows in a timely manner.

l l

l FEMI UNIT 2 E 3.4.1 - 8 Revision 2. 01/18/99

f F.ecirculation Loops Operating B 3.4.1 BASES REFERENCES 1. UFSAR. Section 6.3.3.

2.

NEDE-23785 P A. " SAFER /GESTR Models for the Evaluation of the Loss of Coolant Accident." Revision 1. October 1984.

3. MDE-56 0386. " Fermi 2 Single Loop Operation Analysis."

Rev.1. April 1987, and NEDC-32313 P. "Enrico Fermi Energy Center Unit 2 Single Leop Operation." September 1994.

I 4 CF 50. Appen A. GDC 2.

/

NR Generic ter 94- . "Lo g- rm Solu

ons an U rade of terim 0 ratin ommenda ans for J

P ermal H raulic I stabi s in Bo' ing Wat eactors July 1 4.

6. BWROG etter 9 78. "o er roup Gui elines or Inte m Corr tiveget'o Jun 1994 g

y

)

F EF *d UNIT 2 53.".1-9 Revision 2 01/13/99

Recirculation Loops Operating ,

B 3.4.1 BASES x

f ,

! , ')

f l ,I

\

/ /

/

l

/

Y A TEP.

, ,/

t l

/ r

, /

, ,/

/

/ '

,/ ,/

/ '

, e / '

, ,' /

I .

k

/ / l

{ / /

1 '

/ /

- /

\

/

f t

TriEPyAL . POWER vs COPl' FLOW

/

//\\

f g i

F1gure E 3 A.1 1 ;

l l

i -

- /

FEEMI U!i1T 2 B 3.4.1 - 10 Revision 2. 01/18/99

l Enclosure 4 to NRC-99-0048 t Page1 l

l l

i t

l

[

i ENCLOSURE 4 OPRM CORNER FREQUENCY. PEMOD TOLERANCE, AND MAXIMUM PERIOD DISCUSPION, PROPOSED SETPOINT RANGE REVISIONS, AND ASSOCIATED JUSTIFICATIONS l

1 l

i

Enclosure 4 to NRC-99-0048 Page 2 Detroit Edison Fermi 2 OPRM Corner Frequency, Period Tolerance, and Maximum Period Discussion, Proposed Setpoint Range Revisions, and Associated Justifications

Background

LTR NEDO-32465-A, " Reactor Stability Detect and Suppress Solutions Licensing Basis Methodology for Reload Applications" describes the licensing basis methodology for the Option IIIlong term stability solution. The licensing basis for this solution is the period based algorithm (PBA) which relies on the fact that OPRMs, composed of cells of closely spaced local power range monitors (LPRMs),

can be used to distinguish between thermal-hydraulic instabilities and stable reac'or operation. During normal, steady-sta:e reactor operation, LPRM signals are comprised of a broad range of frequencies that are typically present in a boiling water reactor (BWR). These LPRM signals become more coherent displaying a ,

characteristic frequency in the 0.3 to 0.7 Hertz (Hz) range with the onset of thermal- !

hydraulic instability. The PBA uses the difference in LPRM signal coherence to detect instabilities. The coherence persists when signals from closely spaced LPRMs are combined in OPRM cells.

Specifically, the OPRM combines signals from LPRMs assigned to the OPRM cell and determines each successive pair of OPRM cell maxima and minima. If the maxima / minima have a frequency in the range of 0.3 to 0.7 Hz, the base period is set.

If the subsequent maxima / minima occur within a specified tolerance band of the base period, the oscillation is considered to be a single period confirmation. Subsequent maxima / minima which fall within the specified base period tolerance range cause t.n:

PBA continuous period confirmation (CPC) counter to be incremented by one. This process continues until a maxima / minima is found to be outside the specified base period tolerance range, at which time the CPC counter is reset to zero. The CPC count prior to resetting is termed the maximum continuous period confirmation l I

(MCPC) count.

The CPC for each OPRM cell is evaluated simultaneously. During normal plant operation with large stability margin, non-zero CPC count values are expected due to the random nature of normal neutron flux noise. As shown in the data in Table 1, the largest frequency of occurrence is a MCPC of 1 or greater, with rapidly decreasing frequency of occurrence of higher MCPC counts. The OPRM tuning process, the results of which are discussed in the paragraphs that follow, is intended to optimize the setting values of various OPRM tuning parameters so that the PBA is sufficiently

Enclosure 4 to NRC-99-0048 -

Page 3 sensitive to detect actual core oscillations while not necessarily tripping on normal neutron flux noise.

LTR NEDO-32465-A (Section 3.4.1) describes the acceptable range of values for two OPRM parameters, period tolerance and corner frequency. Both of these parameters can be independently adjusted to tune the OPRM to each plant's unique LPRM noise characteristics. Within the ranges defined for these parameters, the OPRM will provide sufficient CPCs to detect thermal-hydraulic instabilities prior to reaching the PBA amplitude trip setpoint. The ranges presented in NEDO-32465-A were based upon testing the PBA using data taken with analog LPRM signals from several different plants. Data was taken with 50-millisecond sarnple rate during stable and unstable reactor operation. A range for each OPRM setpoint value was defined to ensure that the OPRM is sensitive enough to detect an instability as it develops at low amplitudes while allowing utilities the flexibility to adjust the l OPRM response to their plant's noise characteristics during steady-state operation.

The adjustments to account for noise characteristics are necessary to avoid spurious l

alarms and reactor scrams. Normal operational LPRM signals are viewed by the OPRM as a distribution of MCPCs. The OPRM is tuned based on the MCPC distribution under plant operating conditions that have significant stability margin (i.e., near or at rated conditions). Based upon tuning criteria proposed by GE, the Fermi 2 OPRM setpoints as discussed below provide more than adequate sensitivity. l Fermi 2 Specific Information l

Based on OPRM data collected during Cycle 7, it is apparent that the OPRM is too sensitive when the least sensitive setpoints defined in Table 3-1 of LTR NEDO-32465-A are used (i.e., period tolerance of 100 milliseconds and corner frequency of 2.5 Hz). However, the OPRM design of the PRNM system allows the OPRM period tolerance and corner frequency to be set to less sensitive values than those defined in

' the LTR, i.e., the hardware allows values from 50 to 300 milliseconds and 1.0 to 3.0 Hz, respectively, compared to 100 to 300 milliseconds and 1.0 to 2.5 Hz, respectively, in the LTR. Fermi 2 testing indicates that the OPRM more closely meets the GE tuning criteria under normal operating conditions if a period tolerance of 50 milliseconds and corner frequency of 3.0 liz are allowed to be utilized.

The following factors contribute to the OPRM function being more sensitive than originally anticipated for the Fermi 2 installation:

1) The plant data used to develop the OPRM detection algorithm had a sample frequency of 50 milliseconds. The Fermi 2 PRNM provides LPRM sample data every 25 milliseconds. This sampling rate tends to increase OPRM sensitivity.

2) Fermi 2 noise characteristics differ from those of the reference plants used to test the detection algorithm. Specifically, the PRNM system has improved accuracy,

I l

Enclosure 4 to NRC-99-0048 Page 4 noise immunity, and LPRM signal filtering. The additional LPRM filtering tends to increase OPRM sensitivity, thus producing higher MCPC counts when the plant is operating with a large stability margin.

The maximum oscillation period (T,nax) is the largest expected period which the OPRM would sense if a reactor instability was present. For example, if the time 4 between successive LPRM signal maxima / minima is greater than T,nax, the oscillation is not indicative of an anticipated reactor instability. LTR NEDO-32465-A (Section 4.3.2.4) states that studies of actual instability events indicate that the I expected period is approximately 1.8 to 2.0 seconds. However,it is desirable to consider an oscillation frequency between 0.3 and 0.7 Hz for conservatism. This q corresponds to a T,na, value of approximately 3.30 seconds. The OPRM design allows this parameter to be set in the range of 3.0 to 5.0 seconds. A review of the online test data indicates that Tmax may be set at its lower design limit of 3.0 seconds (frequency of 0.333 Hz) to further ensure adequate sensitivity while balancing the need to avoid spurious OPRM alarms and trips. Based on LTR NEDO-32465-A (Figure 4-5), allowing Tom to be set down to 3.0 seconds does not significantly alter the probability of detecting core instability while helping to minimize the possibility of spurious OPRM alarms and trips.

Table I contains a sampling of Fermi 2 OPRM count data at various OPRM settings collected during Cycle 7 to demonstrate the margin to spurious alarms and trips when the revised OPRM setpoint ranges are utilized. The first two sheets of Table I show data taken at relatively low flow conditions with power at approximately the lower limit of the OPRM-enabled region, while the last two sheets of Table i show data taken at relatively high power and flow conditions with flow above the upper limit of the OPRM-enabled region. The data values highlighted (bolded) in Table I were taken with setting values equal to the final selected values.

fonclusion The OPRM is fully expected to produce enough MCPCs to exceed the alarm and trip setpoints if a thermal-hydraulic instability should occur. Allowing Fermi 2 to use the full range of the tuning parameters allowed by the OPRM design, including the allowance to set the corner frequency, period tolerance, and maximum period up to the limiting value of 3.0 Hz, and down to the limiting values of 50 milliseconds, and 3.0 seconds, respectively, provides acceptable OPRM sensitivity based on upon the foregoing discussions. These setpoint values are slightly outside the ranges described in LTR NEDO-32465-A, which were based on data from a few plants with different power monitoring system designs. However, the values are consistent with the original definition of the PBA in NEDO-31960-A, Supplement 1. The proposed setpoint range changes provide margin to spurious alarms and trips during stable ,

i reactor operation and do not compromise the ability of the OPRM to detect 1

Enclosure 4 to NRC-99-0048 Page 5 instabilities and initiate an automatic reactor scram prior to violating the minimum critical power ratio (MCPR) safety limit for anticipated reactor instabilities.

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