ML20058L847

Safety Evaluation Supporting Amend 53 to License NPF-43

ML20058L847
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Site:	Fermi
Issue date:	07/27/1990
From:	Office of Nuclear Reactor Regulation
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SAFETY EVALUATICN BY THE OFFICE OF NUCLEAR REACTOR REGULATION i

RELATED_TO AMENDMENT NO.53 TO FACILITY OPERATING LICENSE NO. NPF-43 DETROIT EDISON COMPANY FERMI-2 l

DOCKET NO. 50-341 1

1.0 INTRODUCTION

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- By letter dated August 4,1988 as supplemented August 18, 1989, the Detroit Edison Company (Deco or the licensee) requested amendment to the Technical i

Specifications (TS) appended to facility Operating License No. NPF-43 for L

Fermi-2. The proposed amendment would change the Technical Specifications to I

allow extended operation of Fermi-2 at reduced power with a single l

recirculationloopinoperation(SLO).

4 2.0 EVALUA110N 2.1 Single Loop Operation Current fermi-2 TS require shutdown of the reactor within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> when only one recirculation loop is in operation. proposals for TS changes to allow extended operating time under SLO conditions have been accer,ted in recent years for a large number of BWRs with similar restrictions. Thermal hydraulic stability (THS) concerns have been largely resolved for SLO by the introduction of TS requiring avoidance of potentially unstable regions of the power flow map and surveillance in neighboring regions. More recently, interim operating l-procedures requirements described in NRC Bulletin No. 88-07 and Supplement I to that bulletin (Ref. 4) have been ie. sued to address THS.

NRC Generic Letters 86-02 and 86-09 (Refs. 6 and /) present staff positions in the areas of SLO l

and related THS surveillance requirements.

1 In addition to the THS changes, it is necessary to reexamine the analyses of abnormal operational transient and accident events under SLO conditions and I

provide for required changes, including TS changes, of trip set points and operating and safety limits resulting from the changed reactor conditions.

The necessary analyses are provided in the GE report (Ref 3), and DECO has

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i proposed the necessary changes to the TS. These analyses and changes are I

similar to those approved in previous reviews of SLO operations.

1 GE has provided (Ref. 3) the results of the reexamination, and where required reanalysis, of transients and accidents relevant to SLO. The events examined are the same as those considered and approved in previous staff reviews of SLO. These include the abnormal operational transients involving flow increase, y'j'8080226 90o727 p

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t flow decrease, cold water injection, pressurization and rod withdrawal events.

Events requiring analysis have been analyzed with standard, staff approved methodology as described in GESTAR II (Ref. 5). For SLO, these events begin at a maximum power level abcut 30 percent less than that for two loop operation (TLO). Thus maximum transient conditions are for the most part less severe than those analyzed for TLO. Average Power Range Monitor (APRM) and Rod Block Monitor (RBM)tripsetpointequationsrequireadjustmentfortheseanalysisand for operations under SLO conditions to account for the changes in actual core flow versus measured flow as a result of backflow in idle jet pumps. These changes in trip equations in turn require TS changes for SLO.

As is ncrmally the case, the reex6ntination of these transient events by GE resulted in change to safety limits. The operating limit minimum critical powerratio(MCPR)remainsunchangedasdeterminedbyTLO. These results are expected and acceptable.

The safety limit MCPR does change, however. Two of the uncertainties i'volved in the detern.ination of this safety limit are increased b Theseare(1) the random noise for the neutron flux detector readings (y SLO.calledtheTIP*eadings) used for power determination, ar.d (2) core flow measurement uncertainty. The atalyses for these increet uncertainties are the same as has been preser.ted and accepted in previous SLO reviews. The result is an increase of 0.01 in the safety limit MCPR. This is a reasonable and acceptable change.

The only accident event, other than LOCA relevant to SLO is the recirculation pump seizurt. accident.

Itwasnotspecific611yreanalyzedforFermi-2. However, previous reviews for a range of reactors (including a large BWR4 similar to Fermi-2) requesting SLO have provided enalyses, approved by the staff that have shownthattheeventresultsinaMCPRsignificantlyabovetheSLOsafetylimit.

It is concluded that this result is also applicable to Fermi-2.

SLO affects LOCA calculations primarily by decreasing core flow more rapidly than for TLO and thus decreasing the time to departure from nucleate boiling.

To examine this and other effects of SLO, LOCA enelyses were performed using standard, approved methodology and covering a spectrum of large break sizes.

These analyses result in a required reduction factor of 0.90 for Fermi-2 current fuel assembly maximum average planar linear heat generation rate (MAPLHGR) limits. With this limit reduction factor, the large and small break LOCA results reuain within required limits of 10 CFR 50.46. This type of analysis and the reduction factor (of similar n,agnitude) have been reviewed and approved in previous SLO reviews and is acceptable for Fermi-2.

in addition to relevant transients and accidents, GE has examined several other areas possibly associated with SLO. These include containment analysis, ATWS, fuel mechanical performance, and pressure vessel internal vibrations.

As in previous SLO reviews, because of the more limited power flow region of SLO, the reactor conditions associated with these areas for Fermi-2 SLO generally fall within previously analyzed TLO bounds, with results within required limits.

However, to assure conservatism, and in keeping with previous SLO submittals and approvals, there are proposed TS requiring (1) limitations on power (70 percent of rated) and flow (one punp speed 75 percent of rated), (2) additional surveillance on recirculation loop differential tenperature to prevent

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stratification and associated stresses, and (3) manual flow control to prevent possible control oscillations. These are measures approved in previous SLO reviews and are acceptable for Fermi-2.

2.2 ThermalHy,d,r,6ulicStability(THS) l The proposed Technical Specification changes are intended to avoid problems with thermal hydraulic instability which have been a focus of NRC attention followingtheLaSalleinstabilityeventofMarch1988. This attention has i

resulted in the issuance of NRC Bulletin 88-07 and Supplement 1 to that bulletin L

(Ref.4). These provide NRC action requests for utilities to provide operator training, instrunientation verification and operating procedures intended to minimize instability potential or consequences. The requested operating p'rocedures of Supplement 1 are based primarily on the General Electric (GE)

Interin. Recommendations for Stability Actions" (IRSA). The IRSA are presen.ed in an attachnent to the supplement.

Supplement I also requests (1) that ple its without effective autonatic scram protection for regional oscillations (IRSA group 2 plants) should initiate manual scrani upon loss of both recirculation pumps, and (2) that the region boundaries of IRSA be reevaluated and justified for core loading with fuel other than that supplied by GE.

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The IF.SA, along with the other NRC staff requests presented in the supplement, ccostitute current itRC recommendations for BWR THS related operations. They are the result of calculations and reviews by the itRC, GE, the BWR Owners' Group and associated consultants. The bulletin supplement requested that licensees implen;ent the IRSA (and other associated requests) by modifying rt1(vant procedures. Modification of TS was not specifically requested since it is expected th6t long term solution implementation, to replace the interim reconnendations, will begin soon. However, several licensees have niodified their stability TS to correspond to the bulletin requests, rermi-2 currently has THS restrictions procedures and relevant power-flow map regions, but they differ in many dett 41s fron. those requested in Supplement 1.

furthermore, Fern.i-2 is a IRSA group 2 plant (havirs a filtered APRM flow biased l

ncutronfluxsignaltoprovideasimulatedthermalpowermonitor),andhas l

current and future core fuel loadings consisting of GE P8x8R and GE 8x8B fuel l

assen blies. This requires changes in Fermi-2 operations and power flow m6p region boundaries to ccmply with the Supplement I requests. DECO has therefore subr.itted proposed TS changes and justifications to provide specifications which comply with the NRC requested changes.

Tht IRSA specify three regions (A, B, C) on the power-flow niap involving l

different degrees of allowed or prohibited operation. These are bound 5d by constant flow lines or control rod lines (lines of flow variation with other reactor parameters, particularly control rod position, held constant). Region A is above the 100 percent rod line (intercepts 100 percent rated power at 100 percentratedflow)andbelow40percentflow.

Region B 's between the 80 and 100 percent rod lines and below 40 percent flow.

Region C is above the 80 percent rod line and between 40 and 45 percent flow. Deliberate entry into regions A and E is not permitted, and if it occurs, immediate exit is required.

For a group 2 plant (such as fermi-2) inmediate scram is required in region A, while the region B control rod insertion or flow increase may be used to exit.

Operations may be conducted in region C, with suitable surveillance, if I

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• required durir.g " start-ups" to prevent fuel damage.

If during operations in B or C instability occurs, the reactor shall be scrammed, with evidence for instability coming from Average Power Range Monitor (APRM) ost.illation greater than10percentorLocalPowerRangeMonitor(LPRM)upscaleordownscale alarms.

The new stability requirements are independent of the number of recirculation loops operating. The new Fermi-2 regions are displayed in the Figure 3.a.10-1.

Iniediate strem is required if region A is entered. The IRSA regions B and C are con,bir.ed,oto a single Region B.

The IRSA operating restrictions of region B were conservatively applied throughout Fermi-2 Region B.

In Regich B, control rods instrtion is required innediately. The proposed regions provide a conservative representation of the Suppleroent 1 request and are acceptable.

The overall conclusion of the review is that the proposed TS changes and tha material suttritted to support the chances are acceptable.

It should be noted, however,thattheNRCstaff,itsconsiltents,theBWROwners' Group (BWROG),

GE, and others are continu N the re',iew of THS concerns. The CWROG is developing several long ters * ';ons for the problem. Any new requiren'ents resultirg from the continuing generic review of THS concerns and CWP0G long terni solutions will be applicable to Fermi-2 and may impact some of the operations, systems surveillence, or TS found to be acceptable in this review.

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3.0 TECMICAL SPECIFICATIONS Deco has proposed that the following TS be changed to provide for SLO and THS 1

requireirents.

For the niost part the reasons for these changts have already been discussed and staff approval indicated.

Specification 2.1.2. - The safety limit MCPR is changed to 1.08 for SLO.

It reiCa'fiii'W T.ID f or TLO. This increase of 0.01 because of increased power and ficw rioise and uncertainty, as previously discussed, is acceptable.

Specification 2.2.1 - Added footnote to specify tinie allowance of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to ccnply vii~th'3LO requirernents. The staff finds four hours is acceptable for not declaring the APRM flow biased instrumentation inoperable.

Table 2.2.1 The APRM trip set point change for SLO is added. This change to accoubt for the difference in rc.easured and actual core flow, as previously discussed, is acceptable. No high flow clamp is required since flow levels are not attainable during SLO.

Specification 3.2.1 - The reduction of 0.90 for the SLO MAPLHGRs is provided.

As discuss'e'(f wow in Section 2.1 the reduction of 0.90 for the SLO MAPLHGRS

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Leeps the large and small break LOCA u.alysis within the limits of 10 CFR 50.46.

Therefore the staff finds the change acceptable.

Specification 3.2.2. - This also changes the APRM trip set point equation 6nd control rcd tNcY's'et points to account for lower core flow ccnditicns under SLO conditions. The staff finds this acceptable.

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Tabic 3.3.6-2. - Along with the scram trip set points, the roo block type set po'ist's are added to the TS for both the AFRM and RBM to account for SLO trips.

The staff finds this acceptable.

S>ecification 3.4.1.1. - This specification receives a nunber of additions and clar.ges to acc'o'uYt'To'r requirements for SLO. These include, in the Action

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section, requirements for flow control in Local Manual mode, awer level not above 70 percent, MAPLHCR limit reduced by 0.90, pump speed rot above 75 percent, differentiel tenperature surveillance for power not above 30 percent or for recirculation flow above 50 percent, and reduction of ApRM and RBM trip set points. These action itenis have been previously discussed and are acceptable.

The associated action times are siniilar to those previously reviewed and approved for SLO and are reasonable and appropriate for Fermi-2. The Vequired sur u illance and frequencies are reasonable 6nd genere11y in accord with previous reviews ar.d are ecceptable.

Specificetion 3.4.1.4. - The proposed ch6nge includes an additional restriction 1

for idfe'YtFp'st'a'r't-up which is based upon thermal hydraulic instability concerns. During an idle loop start-up there is a potentiel for thernial hydraulic instability if thermal power Is not restricted to below the 80% rod line shown in the proposed Figure 3.4.1.4-1.

Accordingly, the LCO, action and survtillance requiren'ents have been nodified to prohibit idle loop start-up in the region of concern. The proposed change is acceptable.

!!.W..Sf?.C.I.f.if a,t.i,op,.,, 3/,4,d,),0,,Cpy,,T hyJga,1, Hy d ra u l i e S t a b i 11 ty The proposed TS 6dds a new core flow n.ap defining crerability boundaries. The proposed TS ccrcplies with the steff approved interin, stability corrective actions for DWRs using GE fuel and hence is ecceptable.

Sfff.i.f.i.C.6.t,1,cp,,3/,4 ),0,,Sppp,1,a,1,,Tp,s,t,,E,xppp,t i on s R e t i r c u l a t i o n L oo p s j

This specificatioc nas been modified to reflect th61 the provisions which 611 owed epplication of the exception to operation condition-1 is no longer evailat le. This is currently allcwed during the start-up test progr6m; however, the start-up test program has been completed. Therefore, it is proposed to sinplify the specific 6 tion by eliminating reference to the expired provisions.

This is acceptable.

There are minor changes to Bases 2.2.1,3/4.2.1, Bases Table B 3.2.1-1,3/4.4.1 and the new 3/4.4.10 addressing the above TS changes. They suitably reflect the TS changes and are acceptable.

We have reviewed the reports subniitted by DECO for Fermi-2 proposed TS changes relating to SLO and THS.

Cased on the above review, the staff concludes that appropri6te documentation was submitted and th6t the proposed changes satisfy staff positions and requirements in these areas.

Extended SLO operation and THS monitoring in the n.anner thus described, and as augn.ented by con.pli6nce to the requests of NRC Eulletin 88-07 and Supplen.ent 1, is acceptable.

4.0 ENVIRONMENTAL CONSIDERATION

This amendnent involves changes in a requirement with respect to the installa-tion or use of a facility corponent located within the restricted area as

5 defined in 10 CFP Part 20 and ch6nges in surveillance reouiren.ents. We have detert:,ined that this eniendnent involves no significant increase in the arnounts, and no significant change in the types, of any effluents which may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation 0xposure. The Conunission has previcusly issued a proposed finding that this amendment involves no significant hazards considera-tion and ther( has been no public consnent on such finding. Accordingly, this amendrient ineets the eligibility criteria for categorical exclusion set forth in10CFR51.22(c)(9).

Pursuant to 10 CFR 51.22(b), no environn, ental impact staternent or environmental assessment need be prepared in connection with the issuance of this amendment.

5.0 CONCLUS!0]LS I

Fe have concluded basedontheconsiderationsdiscussedabove,that(1) thcreisreascnableassurancethatthehealthandsafetyofthepublicwill not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Con'rrission's regulations, and (3) the issuance of this aniendment will not be inimical to the common defense and security or to the health and safety of the public.

6.0 REFERENCLS 1.

Letter and enclosures from B.R. Sylvia, to NRC, dated August 18, 1989, "Supplen.ent to TS change License Amendment to include Single Loop Operations."

2.

Letter from Williani S. Orser, to NRC, dated August 4,1988, " Proposed Technical Specification changes to include Single Loop Operation (SLO).

3.

GE report HDE-56-0386, " Fermi-2 Single Loop Operation Analysis," April 1987.

4.

NRC Bulletin No. 88-07:

power Oscillations in Boiling Water Reactors (BWRs), Jur,e 15, 1988 and NRC Bulletin No. 88-07, Supplement 1, December 30, 1988.

l 5.

GE report GESTAR 11, NEDE-24011-P-A-6, dated April 1983.

6.

Generic Letter No. 86-02, " Technical Resolution of Generic Issue B-19 Thermal Hyraulic Stability " January 23, 1986.

7.

Generic Letter No. 86-09, " Technical Resolution o,' Generic Issue No.

l B-59-N-1 Loop Operation in BWRs and PWRs," March 31,1986.

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DATE:

July 27,1990 I