ML17221A713

Forwards Addl Info on Proposed License Amend Re Boric Acid Concentration Reduction,Per NRC 880310 Telcon Request

ML17221A713
Person / Time
Site:	Saint Lucie
Issue date:	04/06/1988
From:	Conway W FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
L-88-168, NUDOCS 8804120332
Download: ML17221A713 (11)

Text

REGULA Y INFORMATION DISTRIBUTIO YSTEM (RIDS)

ACCESSION NBR: 8804120332 DOC. DATE: 88/04/Ob NOTARIZED: NO DOCKET 0 FACIL: 50-335-St. Lucie Planti Unit ii Florida Power 5 Light Co. 05000335 AUTH. NAME AUTHOR AFFIL1ATION CONMAY> W. F. Florida Power 5 Light Co.

RECIP. NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Forwards addi info on proposed license amend re boric acid concentration reductions per NRC 880310 request.

DISTRIBUTION CODE: A001D COPIES RECEIVED: LTR i ENCL I SIZE:

TITLE: OR Submittal: General Distribution REC IP IENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-2 LA 1 0 PD2-2 PD 5 5 TOURIGNY> E 1 1 INTERNAL: ACRS 6 6 ARM/DAF/LFMB 1 0 NRR/DEBT/ADS 7E 1 1 NRR/DEST/CEB 8H 1 1 NRR/DEST/ESB 8D 1 1 NRR/DEST/MTB 9H 1 1 NRR/DEST/RSB 8E 1 1 NRR/DOEA/TSB 11 1 1 ILRB12 1 OQC 15-B-18 1 0 01 1 1 RES/DE/EIB 1 EXTERNAL: LPDR 1 NRC PDR NSIC 1 1 TOTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 24

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'APRIB 0 6 1988 L-88-168 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:

Re: St. Lucie Unit 1 Docket No. 50-335 Request for Additional Information Boric Acid Concentration Reduction Per letter L-88-37 dated January 22, 1988, Florida Power Light Company (FPL) submitted a proposed license amendment concerning boric acid concentration reduction at St. Lucie Unit l. A telephone conference call was held between FPL and the St. Lucie NRC Project Manager on March 10, 1988 to discuss questions relating to this submittal. The purpose of this letter is to provide FPL's response to certain of these questions as discussed during the conference call.

Should there be further questions, please contact us.

Very truly yours, W. F. Con y Acting Group Vice President Nuclear Energy WFC/MSD/gp Attachment cc: Dr. J. Nelson Grace, Regional Administrator, Region USNRC II, Senior Resident Inspector, USNRC, St. Lucie Plant MSD.RAI

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ST. LUCIE UNIT I rc Acro coNcErrrorrrrorr REovcrrO FPL RESPONSE TO NRC RE(VEST FOR ADDITIONAL INFORMATION I. Containment Sum and S ra H Evaluation The following abstract is provided to delineate the methodology employed to evaluate the effect that reduced boric acid concentrations would have on the Containment Sump and Spray pH:

As part of the boric acid concentration reduction program, the existing Florida Power

& Light Containment Sump and Spray pH calculation was revised to reflect the new operating parameters for the Boric Acid Makeup (BAN) Tanks as specified by Combustion Engineering (Reference CE Letter No. F-CE-10325 dated October 27, 1987). Based on the results of the revised calculation, the operating concentration range for Sodium Hydroxide (NaOH) in the Chemical Storage Tank (CHST) is amended to reflect lower boric acid concentrations as delineated in proposed Technical Specification 3.6.2.2.

To analyze the worst case pH conditions, the calculation involved an iterative process whereby the maximum and minimum boric acid concentrations and water volumes for all available borated water inventories were considered. The calculation was separated into two parts: 1. Containment Sump pH Evaluation; and 2. Containment Spray pH Evaluation.

The Containment Sump pH Evaluation determined the high and low sump pH considering worst case mixing of available borated water inventories. The Containment Spray pH Evaluation determined the high and low containment spray nozzle pH during both injection and recirculation modes. The Containment Spray pH Evaluation required the analysis of the following conditions: off-site, power available, no failures; off-site power available, single containment spray pump available; and loss of off-site power, single diesel generator available. When the calculation was revised for this task, all parts were reworked to determine potential impact on the operating pH limits.

Based on the results of the Containment Spray pH Evaluation, the pH at the containment spray nozzles was found to exceed the maximum allowed pH of 11.0. This condition was found to exist during the beginning of recirculation for each of the three cases identified above. In order to maintain containment spr ay pH within the allowable range of 8.5 - 11.0, the CHST NaOH concentrations were adjusted and iterations performed until tank concentrations were consistent with the required pH values at the spray nozzles. The proposed modification to Technical Specification 3.6.2.2, Chemical Storage Tank NaOH concentrations, (from 30% - 32% to 28.5% - 30.5%

by weight) reflect thecalculation results.

II. Reactor Auxiliar Buildin Tem erature Measurement QUESTION:

In regards to the surveillance required when the Reactor Auxiliary Building air temperature is less- than 55 F and considering the physical size of the multi-level building, please discuss the location(s) where the air temperature(s) will be taken and the relationship between the location(s) and the location(s) of all components of the BAMU system.

RESPONSE

As delineated in Figure 1, the affected heat traced piping/components which comprise the Boric Acid Makeup system (i.e. the boric acid makeup tanks, boric acid makeup

located in rel atively ping and piping to th~uction of the chargingthepumps~re p>

'lose proximity on the minM 0.5 ft. elevation of ReaCWI Auxiliary Building. The 32.75 ft.

exception is the boric acid makeup tanks, which have tank tops at elevation as shown on Figure 2.

to In addition, the Reactor Auxiliary Building Ventilation System is designed Safety maintain a uniform temperature throughout the building (

Reference:

Final Analysis Report Section 9.4.2.2. 1). Based upon the above, the Reactor Auxiliary Building air temperature measurement will be taken at the Boric Acid Makeup Station as shown on Figure 1.

III. Boric Acid Makeu Tank Concentration QUESTION:

Proposed Technical Specification 3. 1.2.8.a. requires a boric acid weight percent range of 3.2 / to 3.5 /. Proposed T.S. 3. 1.2.8.b. requires a similar range. Please explain these two proposed Technical Specifications in relationship to (1)Figure the proposed bases statements per the proposed Page 63/4 1-2 Insert, (2) proposed

3. 1-1, (3) FPL's boric acid concentration reduction safety evaluation, and (4)

Combustion Engineering Report CEN-353.

RESPONSE

As delineated in proposed Technical Specification Figure 3. 1-1, proposed Page B3/4 1-2 Insert, and the Combustion Engineering Report CEN-353, the reduction of boric acid concentration to 2.5/o to 3.5%%u by weight requires borated water volumes of 13,300 (2.5/o wt.) to 8350 (3.5/. wt.) gallons. The boric acid makeup tanks are capable of holding 9450 gallons each (the high level alarm is set at 97.5/ of the 9700 gallon tank capacity). In order to maintain the required borated water inventory in one boric acid makeup tank and comply with the proposed Technical Specifications, the boric acid concentration must be no lower than 3.2X by weight.

Technical Specifications 3. 1.2.8.a. and 3. 1.2.8.b. are written to delineate the boric acid concentration requirements (3.2/. to 3.5/) when only one boric acid makeup tank is credited with being in service.

IV. Boric Acid Concentration Reduction Uncertainties QUESTION:

Page 3 of the Florida Power & Light boric acid reduction safety evaluation specifies the uncertainties considered. Please provide: 1) a brief discussion of the uncertainties utilized for scram worth, moderator temperature coefficient and Ooppler coefficient; and 2) an explanation for the omission of boron measurement uncertainties from the analysis.

RESPONSE

A combined bias and uncertainty of 10% was applied to'he scram worth data supplied to Combustion Engineering from Florida Power 5 Light. This combined bias and uncertainty is, consistent with the licensing methodology used by Florida Power 5 Light's Unit' fuel vendor (ANF) to calculate shutdown margin. The scram worth is additionally conservative because it is assumed tnat tne most worthy control element assembly is stuck out of the core during the scram.

A conservative correction was applied to the moderator cooldown curve supplied to Combustion Engineering from Florida Power 8 Light. Since Combustion Engineering did

not generate the modera~ temperature coefficient correction was applied to~is curve to make it (~ curve, a conservative consiste~with the methods used by Combustion Engineering when generating a cooldown curve for the most negative technical specification MTC limit of -0.00028 delta rho/ F.

The application of a bias of 15 /o and an uncertainty of 151 to the Doppler coefficients is consistent with the licensing methodology used for analog plants.

These factors were used inthe analysis.

A boron measurement uncertainty was included in the Louisiana Power & Light physics data when the natural circulation scenario assumed that the boronometer concentration would be used to verify reactor coolant system (RCS) boron concentration. A very conservative boronometer measurement uncertainty (50 ppm) was added to the RCS boron requirements. A review of the cooldown scenario shows that the addition of a boronometer measurement uncertainty to the RCS boron requirements is unnecessary. The cooldown scenario in CEN 353(F) identifies the minimum volume of boric acid makeup tank water will ensure that the RCS is adequately borated. The boronometer readings will not be used during the cooldown as a criteria to reduce the amount of boric acid makeup tank water delivered to the RCS during this cooldown. In conclusion, boronometer measurement uncertainties need not be included in the boration requirement curves for either plant.

V. FIGURE 3.1-1 QUESTION:

In regard to proposed Figure 3. 1-1, please explain why it is necessary to have at the bottom of the figure the expression" 1720 ppm in the RWT."

RESPONSE

have reviewed Figure 3. 1-1 and have determined that the expression "1720 ppm in We the RWT" at the bottom of the figure is 'ot necessary. Therefore, we propose to remove this expression (See attached revised Figure 3. 1-1). r VI. Boration S stem Bases Ouring a telephone call on March 16, 1988 between the Nuclear Regulatory Commission St. Lucie Project Manager and Florida Power & Light, a follow up question was discussed regarding boric acid addition volumes as delineated in Technical Specification Bases Pages B3/4 1-2 and B3/4 1-3. The boron addition capability for Modes 5 and 6, as discussed on Bases Page B3/4 1-3, included conservatisms outlined in CEN-353(F), "Boric Acid Concentration Reduction Effort." However, the boron addition capability for Modes 1-4, discussed on Bases Page B3/4 1-2, do not include the conservatisms outlined in CEN-353(F). In order to provide consistency in the Bases discussion, we propose to revise the boron ranges for Modes 1-4 to include the appropriate conservatisms.(See attached revised insert Page B3/4 1-2).

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