ML20045D591

Proposed TS 3.5-3 Re Operability of RHR & Core Spray Sys During Mode Changes & 3.5-4 Re Operability of Suppression Pool Spray Loop & Drywell Spray Loops

ML20045D591
Person / Time
Site:	Duane Arnold
Issue date:	06/18/1993
From:	IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT
To:
Shared Package
ML20045D587	List: ML20045D586 ML20045D591
References
NUDOCS 9306290190
Download: ML20045D591 (11)

Text

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DAEC-1 LI . TING CONDITION FOR OPERATION SURVEILLANCE REQUIREMENT l 3. The LPCI Subsystem shall be 3. LPCI Subsystem Testing shall be l OPERABLE whenever irradiated fuel .as follows:

is in the reactor vessel, and Item Frecuency prior to reactor startup from a i COLD CONDITION, except as a. Simulated Annual specified in 3.5.A.4, 3.5.A.5 and Automatic '

3.5.G.3 below. Actuation Test  ;

b. Pump Once/3 months Operability

c. Motor Operated Once/3 months Valve Operability

d. Pump Flow Once/3 months Rate Three LPCI pumps shall deliver 34,400 gpm against a system head corresponding to a vessel pressure of 20 psig-based on individual pump tests.

e. Once.per shift visually inspect and verify that RHR-valve panel lights and instrumentation are functioning normally, i

4. With one RHR (LPCI) pump  !

inoperable provided the remaining  ;

RHR (LPCI), active components, both Core Spray subsystems, the containment spray subsystem, and  ;

the diesel generators are verified )

to be OPERABLE, restore the l

l inoperable RHR (LPCI) pump to h LfC1sdsysh de" U l OPERABLE status within 30 days. g) & __k 4 1*, -m*) l

5. Wi t = " " (LPCI p-- =

J g g bli,_ gjyid;)- ot Core Se. LPCI sdsysh^

5 pray subsystems, t e containment spray subsystem, and the diesel _ _ _ _

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Amendment No. 174 3.5-3 09/91 l 9306290190 930618 PDR- ADOCK 05000331 P PDR

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DAEC-1 LIMITING CONDITION FOR OPERATION SURVEILLANCE REQUIREMENT

6. Otherwise, be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

B. Containment Spray Coolina B. Containment Sprav Coolina Capability Capability

1. The suppression pool and drywell spray modes of the residual heat Surveillance of the containment I removal (RHR) syst m spray loops shall be performed as l OPERABLE with tw in c cadcat foll0WS:

l loops each when the re r ater i temperature is greater than 212*F 1. During each five year period, an except as specified in 3.5.B.2 and l

i 3.5.B.3. air test shall be performed on the drywell and suppression pool spray

2. With one suppression pool spray headers and nozzles, loop and/or one drywell spray loop erable, restore the inoperable l=pb to OPERABLE status within 30 ays or be in at least HOT SHUTDOWN l within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in I COLD SHUTDOWN within the following

( 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

3. With both suppression pool spray loops and/or both drywell spray loops inoperable, restore at least one loop o OPERABLE status with N 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> o be in HOT SHUTDOWN within the ext 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTD0 4 within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

OEeachSyujhte (sgresse pot .A bp=ll i

l Amendment No. 174 3.5-4 09/91

- - = . . . . .. = . .- . _ _ _ _ - _ _ _ _ _

DAEC-1

. 1 3.5 BASES A. Core Spray and LPCI Subsystems o

This specification assures that adequate emeroency cooling capability is )

available whenever irradiated fuel is in the reactor vessel.

NE n.DC-23185-P l

l Based on the loss-of-coolant accident (LOCA) evaluation models described in

! General Electric Topical Report @(5^jb (Ref. 2), the results of the LOCA analysis given in Reference 3 and Subsection 6.3 of the Updated FSAR'and in accordance with the acceptance criteria of 10CFR50.46, any of the following Cebidh hoolingsystemsprovidessuffiientcoolingtothe ore to dissipate the  !

des e Asis 4 l energy associated with theg oss-of-coolant accidentj t: ' Sit calculated l-fuel c!;d te per:ture to 1000 than 2200*F t :::ure that core gccmetry l -em:in 4 tact, and te '-it clad -^tal water rc:ction te 10;; than 1%:  ;

f either of the two core spray subsystem; and the L"CI subsystem.

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b^5"E O p (g)

The /imitina /onditionsgef-/peration3in Specification 3.5.A.1 through

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3.5.A.6 specify the combinations of iI'e}able]subsystemstoassurethe availability of the minimum cooling systems noted above.

l Amendment No. 88 3.5-14 94/83

Insert A:

{ Indent 5 spaces}

a. Two LPCI pumps, one Core Spray loop, the Automatic Depressurization system, and the HPCI system (14, single Diesel-Generator failure).

b. Two LPCI pumps, one Core Spray loop, and the Automatic Depressurization system (la, ;

Division II 125V battery failure).

c. Four LPCI pumps, two Core Spray loops, and the Automatic Depressurization system (iA, HPCI failure).

d. Two Core Spray loops, the HPCI system, and the Automatic Depressurization system (la, LPCI injection valve failure).

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DAEC-1 1

C. ore spray distribution has been shown, in full-scale tests of systems similar in design to that of o exceed the minimum requirements. In addition, cooling effectiveness has been demonstrated at less than half the rated flow in simulated fuel assemblies with heater rods to duplicate the decay heat characteristics of irradiated fuel. The accident analysis is addit' conservative in that no credit is taken vesse for spray coolant entering the reactor3 before the internal pressure has fallen to 150 psi 9.

g96 The LPCI subsystem is des'gned to provide emergency to ing to the core by flooding in the event of a loss .-coolant accident. Thishfunctions in combination with theforefprayget--topreentexcessivefuelcladtemperature. The LPCI subsystem  ;

and the fore )Ipray subsystemfprovide adequate cooling for break areas of approximately  !

0.2 square feet up to and including the double-ended recirculation line break without assistance from the high pressure emergency core cooling subsystems. -

The allowable repair times are established so that the average. risk rate for repair would be no greater than the basic risk rate. The method and concept are described in Reference 1.

Using the results developed in this, reference, the repair period'is found to __ l _

be 1/2 the test interva{This assumes that the_ hre fpray subsystems and constitute a 2 cut of ? r . ; however, the combined effect of any cf the two subsystems to limit excessive c d tem eratures must also be considered.

bd cf s 'Mems l The surveillance requirements provide adequate assurance that the Core Spray I subsystems and the LPCI subsystem will be when required.

(Inser

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Coolh\S Should the loss of one " pump occur, a nearly full co, ement of core and g containment spray equi ment is available. The remaining three 4-PG.I. pumps and forefpraysubsystem ill perform the core cooling function. Because of the availability of the ma ority of the core cooling equipment, which will be

, verified to be a ,L e rn r stified. If the LPCI I sub able 3:t . ::" LPCI g ap uj 3 available to fulfill the qcr,tair pig g function.

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7 day repair period b :i:. l EMC Fm%is M,ne M uca.E.guind asis, gyeoaed .Hus+ 2tA t

l Amendment No. 174 3.5-15 4P rsare. W ie Lw s.Rscy u 09/91 l l @p=f eo D.5.s.Ah

Insert B: .

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In addition to the OPERABILITY requirements of having a hydraulic flowpath from the l Suppression Pool to the Reactor Pressure Vessel (RPV) at the required head and flowrate (3 RHR pumps @ 14,400 gpm with the RPV @ 20 psig), the LPCI subsystem must also be i capable of directing this flow into the appropriate Reactor Recirculation loop. Consequently, the LPCI " Loop Select Logic" instrumentation (Specification 3.2.B) and LPCI " Swing Bus" (Buses IB34A and IB44A) must also be OPERABLE to support the LPCI function.

Insert C:

{1}

In the course of a plant shutdown, during the transition from HOT SHUTDOWN to COLD SHUTDOWN, the RHR system must be re-aligned from its standby-readiness mode (iA, LPCI) to the Shutdown Cooling mode. While the system must be manually re-aligned from the Shutdown Cooling mode back to the LPCI mode upon demand, the LPCI mode may be considered OPERABLE for the purposes of satisfying Specification 3.5.A.5, as the system I will be operating (iA, known to be OPERABLE); this re-alignment is a normal plant I

evolution; and, the risk of a LOCA during this transition from the RHR interlock pressure l (135 psig) to COLD SHUTDOWN is minimal. l l

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DAEC-1 B &'C. Containment Spray and RHR Service Water l

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containment spray subsystem for DAEC consists of-2 l' oops eac'h with 2 l pumps a RHR service water pumps per loop. The water pumped thro the RHR  ;

i heat exchanger ay be diverted to two spray headers in the ell and one l above the suppression 1. The design of these systerr s predicated upon use }I l of 1 LPCI, and 2 RHR service ter pumps for he removal after a design basis -

event. Thus, there are ample spare or gin above the design conditions. , l Loss of margin should be avoided a he eq-ai ment maintained in a state of / I l

operability so a 30-day out- -service time is c n for this equipment. If s ,

I one loop is out-of-s ce, or one pump in each loop is l

, -of-service, reactor- j operation is tted for seven days. The surveillance requi nts provide J l 1 adequa ssurance that the Containment Spray subsystem and RHRSW sys will 1 operable when required.

(Lsert'D]

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l Analyses were performed to determine the minimum required flow rate of'the RHR Service Water pumps in order to meet the design basis case (Reference 4) and the NUREG-0783 requirements (Reference 5). (See Section 3.7.A.1 Bases for a discussion of the NUREG requirements). The results of these analyses justify reducing the required flowrate to 2040 gpm per pump, a 15% reduction in the original 2400 gpm per pump requirement.

Amendment No. 174 3.5-16 09/91-l

Insert D:

The Containment Spray subsystem for DAEC consists of 2 loops, each with 2 RHR pumps, I RHR Heat Exchanger and 2 RHR Service Water (RHRSW) pumps per loop. The water i pumped through the RHR Heat Exchangers may be routed to any combination of two spray l headers in the drywell and one above the suppression pool (iA, Wetwell air space). While there is only one suppression pool header, it can be supplied from either spray loop. The functional requirement of these systems is predicated upon use of one loop consisting of 1  ;

RHR p"mp,1 RHR Heat Exchanger and 2 RHRSW pumps for containment heat removal. )

Thus, tnere are ample spares for margin above the design conditions.

While no credit is assumed in the UFSAR accident analysis for use of Containment Spray l (either suppression pool or drywell) (Reference Section 6.2.1.3.3), their use can be beneficial

( in mitigating certain events. Consequently, loss of margin should be avoided and the I

equipment maintained in a state of OPERABILITY, thus a 30-day out-of-service time is chosen for one loop of each (suppression pool and drywell) spray being inoperable.

For the RHRSW system, having one pump out of service degrades the system but sufficient I redundancy remains to support the safety function; thus, a 30-day out-of-service time is appropriate. If one loop is out of service, or one RHRSW pump in each loop is out of service, reactor operation is permitted for seven days, as the system has lost its required redundancy. The surveillance requirements, including In-Service Testing, provide adequate j assurance that the Containment Spray subsystem and RHRSW system will be OPERABLE l when required.

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.RTS-256 Attachment 3 to NG-93-2195 Page 1 of 2 SAFETY ASSESSMENT By letter dated June 18, 1993, Iowa Electric Light & Power Company (IEL&P) submitted a request for revision of the Technical Specifications (TS) for the Duane Arnold Energy Center (DAEC).

The proposed changes will clarify existing TS requirements for the Low Pressure Core Cooling and Containment Spray systems OPERABILITY within the Limiting Conditions for Operation (LCO) and improve the BASES to reflect the actual requirements for i these systems based upon the Updated Final Safety Analysis Report l (UFSAR) accident analysis.

Assessment:

The proposed-changes to the TS clear up ambiguities concerning allowable combinations of out-of-service equipment for the Low Pressure Coolant Injection (LPCI) and Containment Spray modes of the Residual Heat Removal (RHR) system which were inadvertently introduced in an earlier Amendment (No. 174). A footnote has been added to clarify LPCI OPERABILITY during mode changes while the plant is being shutdown, i.e., during transition from the standby-readiness mode (i.e., LPCI) to the Shutdown Cooling mode of RHR. In addition, the BASES for these functions have been improved to better agree with the safety analysis assumptions and conclusions. The corrections and clarifications will ensure that the LCOs for these functions are properly interpreted and that the safety margins established by the safety analysis will be preserved.

The UFSAR for the DAEC describes the analysis of the plant's response to a Loss-of-Coolant Accident (LOCA), with respect to both the ability of the Emergency Core Cooling Systems (ECCS) to prevent core damage, as well as the ability of the RHR system to j remove energy from the Primary Containment and thus preserve its integrity. The results of these analyses are presented in UFSAR Sections 6.3.3 and 6.2.1.3.3, respectively. Due to the " defense-in-depth" philosophy incorporated in the designs of these systems, their overall mission to perform their intended safety functions in responding to a LOCA has been shown in the UFSAR to be satisfied with certain combinations of equipment out of service. Consequently, allowed outage times (A0T) are established within the TS for repairing pieces of equipment within these systems when they are found to be inoperable during various plant operating conditions, as long as the remaining operable equipment is consistent with the analyzed combinations in the UFSAR. The design of the Low Pressure Core Cooling system for the DAEC is based upon a triad of subsystems: Core Spray "A"; Core Spray "B"; and, the LPCI mode of the RHR system. The UFSAR describes the evaluation of the plant's response to a LOCA assuming either the loss of the entire LPCI subsystem (via

.RTS-256 Attachment 3 to ,

NG-93-2195 Page 2 of 2 failure of the inboard injection valve to open) or the loss of a Core Spray subsystem, with acceptable results. Therefore, the TS should provide an allowable outage time for loss of the LPCI subsystem which is commensurate with the AOT for the loss of a Core Spray subsystem. Loss of a single Core Spray subsystem results in a seven day AOT in the existing TS; therefore, a seven  ;

day AOT for the loss of the LPCI subsystem is justified.

I We have compared these TS changes with those of peer plants to the DAEC, i.e., those with custom-formatted TS and designs that pre-date the Standard Review Plan, and found them to be  !

consistent with the requirements contained within the TS for those plants. Also, the proposed changes to the LPCI TS are consistent with the requirements which were in place prior to the

! changes introduced by Amendment 174 to the DAEC TS. The  ;

clarifying footnote for LPCI OPERABILITY during the transition to the Shutdown Cooling mode is consistent with the NRC guidance in l the Standard TS (NUREG-1433) and is therefore judged to be acceptable. -

Based upon the above information, we have concluded that the proposed changes to the DAEC TS are acceptable.

.RTS-256 Attachment 4 to NG-93-2195 Page 1 of 1 I

ENVIRONMENTAL CONSIDERATION j 1

10 CFR 51.22(c)(9) identifies certain licensing and regulatory actions which are eligible for categorical exclusion from the requirement to perform an environmental assessment. A proposed amendment to an operating license for a facility requires no environmental assessment if operation of the facility in accordance with the proposed amendment would not: (1) involve a significant hazards consideration; (2) result in a significant change in the types or significant increase in the amounts of any effluents that may be released offsite; and (3) result in an increase in individual or cumulative occupational radiation exposure. Iowa Electric Light and Power has reviewed this ,

request and determined that the proposed amendment meets the eligibility criteria for categorical exclusion set forth in 10 ,

CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment needs to be prepared in connection with the issuance of the amendment. The basis for-this determination follows:

Basis The change meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9) for the following reasons:

1. As demonstrated in Attachment 1 to this letter, the proposed Amendment does not involve a significant hazards -

consideration. J j 2. The proposed Amendment includes changes which are either clarifications of existing TS requirements or additions which are consistent with NRC Standard Technical Specifications. No changes in either system design or operational strategies will be made as a result of these changes; thus, there will be no increase in either the types or amounts of effluents that may be released offsite.

3. The proposed Amendment includes changes which are either l clarifications of existing TS requirements or additions which are consistent with NRC Standard Technical Specifications. No changes in either system design or operational strategies will be made as a result of these changes; thus, there will be no significant increase in either individual or cumulative occupational exposure.

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