2CAN108704, Application for Amend to License NPF-6,changing Tech Spec to Decrease Boron Concentration Required in Boric Acid Makeup Tank.Review & Approval of Encl Matl in Order to Issue Amend Prior to Next Refueling Outage on 880212 Requested.Fee Pai

Application for Amend to License NPF-6,changing Tech Spec to Decrease Boron Concentration Required in Boric Acid Makeup Tank.Review & Approval of Encl Matl in Order to Issue Amend Prior to Next Refueling Outage on 880212 Requested.Fee Paid

ML20236H165
Person / Time
Site:	Arkansas Nuclear
Issue date:	10/28/1987
From:	Tison Campbell ARKANSAS POWER & LIGHT CO.
To:	Calvo J Office of Nuclear Reactor Regulation
Shared Package
ML20236H167	List: 2CAN108704, Application for Amend to License NPF-6,changing Tech Spec to Decrease Boron Concentration Required in Boric Acid Makeup Tank.Review & Approval of Encl Matl in Order to Issue Amend Prior to Next Refueling Outage on 880212 Requested.Fee Pai ML20236H172
References
2CAN108704, NUDOCS 8711030490
Download: ML20236H165 (9)

Text

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ARKANSAS POWER & LIGHT COMPANY CAPIT0L TOWER BUILDING /P. O. BOX 551/LITTLE ROCK, ARKANSAS 72203/(501) 377 3525 T. GENE CAMPBELL Vice President October 28, 1987 Nuclear Operations 2CAN108704 U. S. Nuclear Regulatory Commission 7920 f:arfolk Avenue Bethesda, Maryland 20814 ATTN: Mr. Jose Calvo, Director Project Directorate IV i

SUBJECT:

Arkansas Nuclear One. - Unit 2 Docket No. 50-368 License No. NPF-6 Technical Specifications Change Request Boric Acid Makeup Tank Boron Concentration Reduction

Dear Mr. Calvo:

The Arkansas Power & Light Company (AP&L) hereby requests an. amendment to its Operating License No. NPF-6 for Arkansas Nuclear One - Unit 2 with the enclosed submittal of proposed changes to the~ Technical Specifications.

These Technical Specification changes provide safety and operational enhancements specifically suited to future extended cycle cores.at ANO-Unit 2. We wish to implement these improvements in conjunction with '

Cycle 7. Therefore, we would' appreciate your review and approval of the ,

enclosed material so that the Operating License Amendment can be issued prior to the start of our next refueling outage which is scheduled to begin on February 12, 1988. The circumstances of the proposed amendment, however, are not of an exigent or emergency nature.

The proposed Technical Specification changes involve decreasing the boron concentration required in the boric acid makeup tanks (BAMTs). The BAMT boron concentration reduction offsets the impact of increased _ concentrations in the refueling water tank and safety injection tanks proposed in a concurrently submitted Technical Specificati noamendment request.

Considered together, these revisions result in:small changes tu the-calculated value of the containment inventory of boron after a LOCA such that the effect on precipitation i.n the reactor vessel and on containment solution pH is~ minimal.

The BAMT boron concentration proposed is sufficiently reduced to warrant the removal of heat tracing from Technical Specification operability requirements. The proposed changes reduce the potential for operational 8711030490 871028 h

PDR ADOCK 050003 8 , {

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L Mr.. Jose Calvo, Director October-28,-1987-

. problems associated with cleanliness.and' corrosion due to' boric'a'cid precipitation. The proposed changes should therefore' improve plant' operations and thereby.. improve plant safety.

AP&L has evaluated.the proposed changes in accordance with 10CFR50.91(a)(3) u' sing the criteria in 10CFR50.92(c) and has determined that these. changes involve no significant hazards consideration. The bases for these-determinations are' included in the enclosed submittal.-

A copy of this amendment request and enclosure has been sent.to Ms.: Greta-Dicus, Acting Director, Division'of Environmental' Health Protection,StateDepartmentofHealthinacc'ordancewith10CFR50.91(b)(1).

A check in-the amount of $150.00 is included herewith as an application ~ fee inaccordancewith10CFR170.12(c).

Very truly yours, I Afn i

.T. Gene Campbel,..

i TGC/sd j l

L Attachments / Enclosures cc: Ms. Greta Dicus, Acting Director Division of Environmental Health Protection-State Department of Health a 4815 West Markham Street l l 'Little Rock, AR 72201 '

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.STATEOFfARKANSAS L) . ,

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I~,'T.' Gene Campbell, being duly sworn, subscribe-to and say;'that I am

'Vice President'of Nublear Operations'for. Arkansas-Power & Light' Company;-

that I have-fu11' authority to execute this: oath;. that I have' rea'd the' l

' document numbered 2CAN198704 and know the content's thereof;"and that=to the; best of.my. knowledge,'information and belief'the statements.Lin;it are.true, a

> f T. Gene:Campbelt i

a SUBSCRIBED AND SWORN T0 before me, a Notary Public in and'for the-County.and State above named, this 2 b day;of ( 2/ 6 ,.

1987.

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ENCLOSURE >. .

LROPOSEDTECHNICAlfSPECIFICATION.CHNNGES P <

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1 PROPOSED CHANGES The proposed amendments to Technical Specifications 3.1.2.1, 3.1.2.2, 3.1.2.6, 3.1.2.7, and 3.1.2.8, Surveillance-Requirements 4.1.2.1, 4.1.2.2; -)

4.1.2.7, and 4.1.2.8 and Bases 3/4.1.? are indicated on-the revised copies i of the pages in Attachment 1. Technical Specifications 3.1.2.7 and 3.1.2.8, '

and Bases 3/4.1.2 also contain changes from the' concurrently' submitted amendment request on the increase in boron concentration in the refueling water tank (RWT) and safety injection tanks (SIT). Attachment 2 is provided to further describe the individual changes and clearly indicate the source j of the changes.  ;

i DISCUSSION Arkansas Power & Light (AP&L) is proposing to reduce the boron concentration required to be maintained in the boric acid makeup tanks (BAMTs), and .

eliminate operability requirements on-the heat tracing associated with these j tanks. The BAMTs serve as a source of borated water for providing '

reactivity control. These tanks are presently required by Technical Specification to contain between 5.0 and 12.0 weight per cent boric acid concentrations depending upon solution temperature and the quantity of boric acid stored in the tank. The BAMTs and the suction lines from the tanks to the charging pumps are heat traced to assure that elevated temperatures are maintained such that the boric acid does not precipitate.

i A concurrently submitted Technical Specification amendment request proposes  ;

an increase to the boron concentration of the RWT and SIT. The proposed reduction of the BAMT concentration of this amendment request offsets the RWT and SIT increase such that the total boron inventory available in containment following a LOCA is not significantly changed. Therefore, the-effects of long term boron concentration in the reactor vessel and the post LOCA containment pH calculations are not significantly changed.

The proposed BAMT concentration requirements will provide adequate control of reactivity. The decrease in concentration will require an increase in available volume. This is accomplished by coordinating the total boron inventory of the BAMTs with the RWT inventory. An option of meeting the BAMT volume requirements by combining the contents of both tanks has also been added because at very low concentrations the required volume exceeds the capacity of a single tank. When both tanks are required, two independent flow paths from each tank must be operable.

The concentration of boric acid currently maintained in the BAMTs creates operational problems. The concentrated boric acid solution presents corrosion and cleanliness problems since any leakage from the system will create highly corrosive crystallized boric acid deposits. The high boric i acid concentrations also create a sustained possibility of pipe plugging due '

to crystallized boric acid precipitation if failure in the heat tracing remains undetected.

The heat tracing requirements for the boric acid makeup tanks and associated flow paths are no longer necessary because the maximum boron concentration in the tanks has been reduced to less than or equal to 3.5WT%. ' Chemical e_______-________________ _ _ _ _ _ _ _ - ~

analyses have shown that a 3.5WT%. solution of boric-acid will' remain dissolved (i.e. , will not precipitate or " plate 'out") at solution temperatures above 50 F. ' Surveillance requirements for verifying flow path and BAMT solution temperature are unchanged except for the new minimum temperature'of 55 F which is a 5 F margin over the maximum precipitation

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temperature. This margin is considered sufficient since the BAMTs and flow paths are housed in areas normally heated for personnel comfort.

In summary, the proposed revision to reduce th'e required BAMT boron concentration will support the proposed increase in concentration of_the RWT and SIT, will maintain reactivity control requirements, and will eliminate

.the operational problems associated with maintaining high boron-concentrations in these tanks.

DETERMINATION OF SIGNIFICANT HAZARDS Arkansas Power & Light Company has performed an analysis of the proposed changes in accordance with 10 CFR 50.91 (a)(1) regarding no significant hazards consideration using the standards in 10 CFR 50.92(c).

A discussion of these standards as they relate to this amendment. request follows:

Criterion 1 - Does Not Involve a Significant Increase in the Probability or Consequences of an Accident Previously Evaluated.

The proposed reduction in boric acid concentration in the BAMTs and the elimination of operability requirements for the heat tracing does not increase the probability or consequences of a previously evaluated accident.

Additicr,s of. borated water from the BAMTs to the reactor coolant system for reactivity control are not credited in any Chapter 15 accident analysis.

The primary source of borated water addition to the reactor coolant system for controlling reactivity during accidents is the refueling water tank.

The reduced BAMT boron concentration was however, evaluated with respect to a) the effect on the ability to maintain required shutdown margins during a cooldown without letdown reported in SAR Chapter 9, b) the effect on the long term boric acid buildup calculation reported in SAR Chapter 6, and c) the effect on the post-LOCA containment pH value reported in SAR Chapter 6.

The cooldown without letdown analysis is prosented in 9.3.4.4 of the'ANO SAR. The required shutdown margin (SDM) is maintained throughout this event by the addition of borated water during the cooldown. The original analysis assumed that all the boron necessary to achieve the required SDM during the entire cooldown was provided by the BAMT during the initial stages of the event. The new analysis includes a detailed evaluation of SDM requirements as a function of RCS temperature and can thereby credit the boron contribution of the RWT. The total boron inventory of the BAMTs can thus be reduced.

The volume of borated water that is required from the BAMTs is shown in the revision'to Figure 3.1-1 (in Attachment 1) for Modes 1-4. During a cooldown with no letdown available, this figure shows the minimum volume of borated E_-_ _ _ _ _ _ - - - - - - - - - - - - - - . - - - - - - _ _ - - - - - - _ _ _ - - - - - - - - - - -

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water necessary to' maintain the' reqdired shutdown' margin during the initial' 3 stages of plant cooldown and depressurization. 10nce this' volume:of water has.been depleted, the plant has cooled down and depressurized to the pointL '

where:the High Pressure Safety Injection (HPSI)' pumps can deliver RWT water:

to the RCS. .The HPSI flow'will inject sufficient borated water.to meet the shutdown margin requirements for;the remainder of the cooldown by-drawing. '

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-its suction from the RWT. 1Thus, bothithe BAMT(s).'and the-RWTJare required. -j to maintain the shutdown' margin requirements during.the cooldown. Since  ;

both these sources'of borated water are being credited, Figure 3.1-1 shows a,  !

smaller volume of BAMT water necessary when there are higher boron '

concentrations in.the RWT.

Previously, Technical Specification 3.1.2.8 'nas required .at--least one. of:the ,

BAMTs to' meet the requirements.of Figure 3.1-1. The proposed change will add the flexibi_lity of meeting the Limiting-Conditions-for Operation (LCO) by combining'the contents of both BAMTs. .This option was.added.because the j

proposed revision'to Figure 3.1-1 allows the boron concentration in-the j BAMTs to go as low as 2.5WT%. In this case, the volume requirement of

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approximately 13,150 gallons cannot be met with.just a single tank.

However, if the combined contents of both tanks are used to comply wiW the. 1 LCO, Technical Specification 3.1.2.2 has been. modified to' require the . '

operability of two additional flowpaths to maintain consistency with the existing specification.

1 In Mode 5 the volume of borated water that'must be maintained is given-in j the proposed change to Technical Specification 3.1.2.7. Thistamount of boron is sufficient to maintain the required shutdown margin during a-Xenon-free cooldown from 200 F to 140 F.

The contents of the BAMTs are assumed to be added'to the containment sump-inventory in the evaluation of long term ECCS performance. ..-The BAMT inventory is assumed .to be added to the containment. in order to a sess the potential for boric acid precipitation in the reactor vessel during ~1or.g term ECCS operation. Since the proposed change involves decreasing the baron concentration in the BAMT, this change will reduce.the' potential for boric acid precipitation during long term ECCS operation. A concurrently submitted amendment request proposes an increase in.the boron. concentration of the refueling water tank and safety' injection tank. These changes offset one another almost exactly such that there is no-change in' the potential for-boric acid precipitation.

The reduction in BAMT concentration and correspond'ing reduction in post LOCA boron inventory also impacts the calculations for the pH v'alue of-the solution in containment following a LOCA. -The increase'in RWT and SIT boron.

concentrations proposed in the other amendment request also offsets this change. The result is a slight reduction in the calculated spray and: sump pH values. The maximum spray pH of 11.0 referenced in Technical ,

specifications bases is still bounding while the minimum. equilibrium sump value of 8.9 has decreased to 8.8. The original decontamination factors for iodine are still valed with the reduced pH values so the change hastno significant impact on iodine removal capabilities. Similarly, since the j solution is still basic, there is no significant impact on containment l corrosion characteristics.

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r In summary, the propose'd changes [do not significant1y' affect the abihity of ,

the unit to maintain required shutdown margins during'cooldown, The-proposed changes do not significantly affect the post-LOCA containment pH value.or the long term boric-acid buildup' calculations. Therefore these changes do not involve'a significant' increase in the probability or consequences of an accident previously analyzed.

Criterion 2 - Does Not Create the Possibility of a New or Different Kind of i Accident from any Previously Evaluated <

The proposed reduction in BAMT boron concentration ~and the elimination of

-operability requirements for heat tracing does not create the possibility.of a new or different kind of accident from any previously evaluated. The BAMT boron concentration reduction changes an existing Technical Specification parameter only. No new or modified equipment.is required and existing operating procedures are not significantly changed. Similarly, the-elimination of heat tracing operability requirements does not significantly ~

alter operating procedures and does not create new or substantial.ly modified equipment configurations.

The ability of the BAMT to fulfill its design function is maintained. ~The inventory from the.BAMTs and the RWT.is sufficient to bring the plant to a ,

cold subcritical shutdown condition from end of life (E0C) reactor coolant l system boron concentration. Because of the substantially reduced bron precipitation temperature, system reliability and hence its ability to fulfill its design function is actually enhanced. Since no new or substantially different equipment or operating configurations are introduced, and since the system functional capabilities are maintained, the proposed changes do not create the possibility of a new or different kind of accident from any previously evaluated.

Criterion 3 - Does Not Involve a Significant Reduction in a Margin of I Safety The proposed reduction in BAMT boric acid concentration and the elimination of operability requirements for heat tracing do not involve any significant reduction in a margin of safety. The boric acid' makeup tanks are not considered in any Chapter 15 transient or accident.

Lowering BAMT boron inventory requirements for the cooldown without letdown is accomplished by the reduction of excessive conservatism in the analysis.

The shutdown margin requirements are still satisfied throughout the event.

The option to use two BAMTs to satisfy' volume requirements-includes the corresponding requirement for redundant flow paths. The new operability requirements are therefore, essentially identical to the original.

For the post LOCA boron precipitation calculations, the increased RWT and SIT concentrations of the concurrently submitted amendment request effectively offset the BAMT inventory reduction. There is e'ssentially no change in calculated containment inventory and consequently no impact.on the time requirement for initiation of the core flush flow.

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z iTheLminorfreductionLin post LOCA' containment minimum. calculated pH.has; ;

insignificant.. impaction,both iodine > removal capabilities:and corrosion character.istics.

The. reduced'boricacidconcentrationand-the1correspondingredubed1

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solubility temperature permit;the; elimination'of.heatLtracing operability.

requirements with~a' net, improvement-inJsystem reliability.,

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' Based o.n these'results, the proposed' changes do'not: involve'any:significant reduction in a' margin offsafety.

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CONCLUSION- ,

The: Commission has provided-guidance-concerning the a 'pplication~off the" standards for determining whether;a significant' hazards consideration...

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exists. This guidance' includes-examples-(51 FR 7750) of types'of: amendments that are considered not likely to. involve.significant hazards .

considerations. .The changes p'roposed in this amendment'are.not'directly comparable to any of;the examplescidentified.in"51.FR 7750. However', 'two other licensees have. submitted Technical; Specification ~ amendments to-implement comparable: changes. Lo'uisiana Power' & Light Company. subm_itted 'an.

amendment to reduce the boron concentration- in .the BAMTs by letter dated

- October 1,1986 for the Waterford Nuclear ' Plant Unit-3. This Technical Specification amendment was subsequently approved.~ . Southern California-Edison Company also submitted-amendments'to: reduce'the' boron concentrations-in the BAMTs by letter dated October 9, 1985 for the San 0nofre> Nuclear s

Generating Station Units 2 and.3i These Technical Specification amendments l were also subsequently l approved. j Based on these evaluations Arkansas' Power and Light has. determined that this l

R proposed amendment does not involve any significant hazards considerations.. 1

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