ST-HL-AE-4281, Application for Amends to Licenses NPF-76 & NPF-80, Respectively,Changing TS to Revise Value of Soluble Boron Concentration in Refueling Canal,Rwst & in SI Accumulators as Described in STP UFSAR & TSs

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Application for Amends to Licenses NPF-76 & NPF-80, Respectively,Changing TS to Revise Value of Soluble Boron Concentration in Refueling Canal,Rwst & in SI Accumulators as Described in STP UFSAR & TSs
ML20127L989
Person / Time
Site: South Texas  STP Nuclear Operating Company icon.png
Issue date: 01/14/1993
From: Rosen S
HOUSTON LIGHTING & POWER CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20127L992 List:
References
ST-HL-AE-4281, NUDOCS 9301280075
Download: ML20127L989 (20)
v • d • e


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The Light c o mp a ny llouston Ughting & l'ower 5 ""d' Texn l'n. jut uninc cennadnpianon i>. o, nos m u .amoron Tein 77m January 14, 1993 ST-ilL-AE-4 2 81 File No.: N3.07.04 G31.02 10CFR50.90 10CFR50.91 10CFR50.92 U. m. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 South Texas Project Units 1 and 2 Docket Nos. STN 50-498; 50-499 Proposed Licensing Amendment Concerning the RWST and SI Accumulators Allowable Boron Concentration Ranaes

Reference:

Letter ST-HL-AE-4277 from S. L. Rosen, dated December 9, 1992 to USNRC Document Control Desk

The purpose of this proposed licensing change is to revise the value of the soluble boron concentration in the refueling canal (during refueling), the Refueling Water Storage Tank (RWST), and in the SI Accumulators as described in the South Texas Project Updated Final Safety Analysis Report (UFSAR) and the Technical specifications.

The proposed change is part of an extensive reanalysis being performed by HL&P in support of a fuel redesign and upgrade. The current refueling boron concentration minimum of 2500 ppm places a design restriction at beginning of life on the STP reactor core.

To increase core design flexibility and improve fuel economy, HL&P proposes to increase the minimum soluble boron concentration required for refueling, while maintaining the current required degree of subcriticalit.*. This proposed increase in boron concentration will cause e.) increase in the required minimum boron concentration in the refueling water storage tank and the safety injection accumulators.

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contained borated water volume in the Boric Acid Storage Tanks An increase in the required minimum during shutdown is also required.

9301280075 930114 PDR P ADOCK 05000490- l PCR j TSc\92-343.001 A Subsidiary of Houston Industries incorporated J (

llouston Lighting & Power Company South Texas Project Electric Generating Station ST-HL-AE-4281 i File No.: N3.07.04 -

G31.02 i

The proposed change in the boron concentration is the first of-two separate changes to the STP Technical Specifications.relati/e H to the reanalyses. A second (OTAT-related) change will follow which will change reactor . protection setpoints and- provide-additional operating margin for STP.

Changing the safety injection accumulator boron concentration '

requires a plant shutdown and would be best implemented for Unit 2 during the Spring 1993, refueling outage. If this propor t change-receives NRC review and approval prior to-Unit 2 resta t .com its Spring-1993 refueling outage, STP Unit 2 will be-able te v.plement 4 the OTAT-related: changes in mid-cycle. Otherwise,. the chenges will be implemented in Unit 2 not later than its fourth refueling. outage in Fall, 1994. Changes are expected to be implemented in Unit 1 during its fifth refueling outage-in Spring,-1994. If the change can not be implemented in the Unit 2 Spring outage, HL&P.will-revise this application socordingly since Unit I would then be the lead unit.

HL&P has reviewed the attached proposed amendment pursuant to 10CFRSO.92 and determined that it involves no significant hazards considerations. The' basis for thla determination is provided in the attachments. In addition, based on the information contained in this submittal and the NRC Final Environmental Assessment for STP Unit 1 anct 2, HL&P has concluded that, pursuant ~to 10CFR51, there are no significant radiological or nonradiological impacts -

associated _ with the proposed action and the proposed license amendment will not have a significant effect on.the quality of the ,

environment.-

The STPEGS Nuclear Safety Review Board has reviewed- and

approved the proposed changes.

In accordance with 10CFR50.91(b), HL&P is providing the State of Texas with a-copy _of this proposed-amendment.

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Houston Lighting & Pcwer Company South Texas Project Electric Generating Station ST-HL-AE-4281 File No.: N3.07.04 G31.02 Page 3 If the NRC should have any questions concerning this matter, please contact Mr. A. W. Harrison at (512) 972-7298 or me at

. (512) 972-7138.

7 S. U. Rosen Vice President, Nuclear Engineering SDP/ag Attachment (s): 1) Summary and Description of Change

2) Determination of No Significant Hazards
3) Marked-Up Technical Specifications for Implementation on Unit 2 only
4) Marked-Up UFSAR Sections for Implementation on Unit 2 only
5) Marked-Up Technical Specification for Final Implementation
6) Marked-Up UFSAR Sections for Final Implementation l

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l TSC\92 343.001

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, ST-HL-AE-4281 File No.: N3.07.04 G31.02-Page!4 h UNITED STATES OF AMERICA i NUCLEAR REGULATORY COMMISSION l

l In the Matter )

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i Houston Lighting & Power ) Docket Nos. 50-498t 50-499--

Company, et al., -;

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i South Texas Project )

Units 1 and 2 )

i i AFFIDAVIT 3

! S. L. Rosen being duly sworn, hereby' deposes and says that he is Vice President, Nuclear Engineering, ~ of Houston Lighting-& Power

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Company; that he is duly . authorized to ~ sign . and . file with ' the Nuclear Regulatory Commission-the proposed amendment concerning the -

!- RWST and SI accumulators allowable boron-concentration ranges;.is i familiar with the content thereof; and:that.the matters set forth i- - therein are true and correct to the best of-his knowledge and:

i belief.

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j S. L. Rosen j Vice President, Nuclear Engineering i

STATE OF TEXAS )

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I Subscribed and sworn t efore me, a Notal.y'Public in and

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for The State of Texas this / . day.of dMah ,.1997.

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Notary Public:in~and fcr the E y A Mg vy commuon dve ns.u State of Texas j _ -H-( - -

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4 Houston Lighting & Power Company ST-HL-AE- 4 2 81 South Texa: Project Dectric Generating Stat.ion File No.: N3.07.04, G31.02 Page 5 l cc:

Regional Administrator, Region IV Rufus S. Scott Nuclear Regulatory Commission Associate General Counsel 611 Ryan Plaza Drive, Suite 400 Houston Lighting & Power Company Arlington, TX 76011 P. O. Box 61867 Houston, TX 77208 George Dick, Project Manager 1 U.S. Nuclear Regulatory Commission INPO 2 Washington, DC 20555 Records Center 4 1100 Circle 75 Parkway i

J. I. Tapia Atlanta, GA 30339-3064 Senior Resident Inspector Dr. Joseph M. Hendrie c/o U. S. Nuclear Regulatory

! Commission 50 Bellport Lane P. O. Box 910 Bellport, NY 11713 4

Bay City, TX 77414 D. K. Lacker J. R. Newman, Esquire Bureau of Radiation Control Newman & Holtzinger, P.C., STE 1000 Texas Department of Health

1615 L Street, N.W. 1100 West 49th Street Washington, DC 20036 Austin, TX 78756-3189 D. E. Ward /T. M. Puckett
Central Power and Light Company l P. O. Box 2121 1 Corpus Christi, TX 78403 J. C. Lanier/M. B. Lee City of Austin Electric Utility Department P.O. Box 1088 Austin, TX 78767 i K. J. Fiedler/M. T. Hardt 4

City Public Service Board P. O. Box 1771 San Antonio, TX 78296 Revised 10/11/91 l

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i NRC SUBMITTAL-PACKAGE

! for the '

! Proposed Revision-to'the_ _

- Refueling Water Storage Tank and'SI Accumulators Allowable Boron concentration Ranges i

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1 ATTACHMENT 1 Safety Evaluation for the i Proposed Revision to the Refueling Water Storage Tank and SI Accumulators l Allowable Boron Concentration Ranges I

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F Attachment 1 i- ST-HL-AE-4281

-Page 1 of 9

! safety Evaluation i for the

Proposed-Revision to the
Refueling Water Storage Tank and SI Accumulators Allowable Boron Concentration Ranges 1.0 Summary The purpose _of this proposed licensing _ change is to revise the ~

. value of the-soluble boron concentration in the refueling canal I (during refueling), the Refueling Water Storage Tank (RWST), and in

' the SI Accumulators as described in the South Texas Project Updated Final Safety Analysis Report (UFSAR) and_ the Technical i Specifications. ,

The proposed change increases the minimum _ soluble- boron concentration in the-reactor coolant system ~and refueling canal to

. 2800 ppm during refueling. The required soluble boron i concentration range in the RWST_is increased from 2500 to 2700 ppm

( to a range of 2800 to 3000 ppm and the soluble boron concentration

! range in-the SI Accumulators is changed from 2400 to 2700 ppm to a range of 2700 to 3000 ppm.

l The changes also cause a change in-the required minimum. contained borated water volume in the Boric Acid Storage System - during shutdown from 2900 gallons to 3200 gallons.- This change is needed

! to-support the increased boron concentration needed in the reactor coolant system-during shutdown and refueling.._ The post-LOCA: hot leg switchover time is reduced from 13.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to 10.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> due to the increased boron concentrations.

l_ NRC review and approval permitting, the proposed changes will-be

implemented in Unit 2 during its refueling outage in Spring, 1993.

l Otherwise, Unit 2 'will -inpicment the changes.not--later than'its

fourth refueling outage in: Fall 1994. Implementation in Unit 1 l will occur during its' refueling outage'in Spring, 1994. If:the NRC L approval. is not supportive of Unit 2 implementing the change in its

(- Spring, 1993 _ outage, HL&P- will_ revise _ the_ proposed _ change l accordin' gly since Unit 1.will then implement the change first. A

,- set of changes to both the Technical Specifications.and the South L

Texas ' Project Updated Final Safety Analysis. Report during the

" Unit 2. Only Implementation"- and the" Final: Implementation" are proposed.

L The effects' of the proposed changes do not pose a significant

. increase'in-hazards.

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Attachment 1-ST-HL-AE-4281 Page 2 of 9 Bafety Evaluation for the Proposed Revision to the

Refueling Water Storage Tank and SI Accumulators
Allowable Boron Concentration Ranges 1

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l 2.0 Purpose The purpose of this proposed licensing change is to revise the

value of the soluble boron concentration in the refueling canal
(during refueling) , the Refueling Water Storage Tank (RWST), and in i the SI Accumulators
in the South Texas Project Updated Final Safety--

j Analysis Report (UFSAR) and the Technical.5pecifications. This

licensing change is requested to support the more reactive cores 1 needed for longer fuel cycle lengths.
In order to attain longer cycle lengths and higher fuel burnups,

, more reactive' cores are needed. However,:the current refueling l boron concentration minimum of .2500 ppm places a restriction at

! beginning of life on the-design of the reactor core. In order to

' maintain the required degree of subcriticality-during refueling, i the soluble boron concentration in the reactor coolant system and the refueling canal should be increased to a minimum of 2800 ppm.

Therefore, the allowable boron concentration range in the RWST needs to be changed to a range of 2800 ppm to 3000 ppm to

accommodate the more reactive cores. The allowable range of boron--

l concentration for the SI Accumulators is also adjusted to be consistent:with the proposed RWST boron-concentration range.

l An increase in the required minimum contained' borated water volume

, in the Boric--Acid Storage System during shutdown is also required.

This change is needed to support the increased' boron concentration j needed in the reactor coolant system during shutdown and refueling.

l The increased boron-concentrations-require that the' post-LOCA hot

' leg switchover time be reduced to prevent exceeding the' maximum boron concentration in the vessel..

l 3.0 Description of Changes

, The proposed ' change revises the minimum required soluble : boron 1 concentration in the reactor coolant system and refueling canal during refueling _(Mode 6) from 2500 ppm to 2800 ppm. This change E causes a: revision to-the soluble boron concentration range in the

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[ RWST from 2500 to 2700' ppm to a range of 2800 to 3000 ppm. Also, the required soluble boron concentration range in the SI i, Accumulators is increased from 2400 to 2700 ppm to a range of 2700 to 3000 ppm.

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! Attachment 1 4- ST-HL-AE-4281 Page 3 of 9 Safety Evaluation

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Proposed Revision to.the i Refueling Water Storage' Tank _and SI Accumulators-Allowable Boron Concentration Ranges l

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These changes also cause a change in the required minimum contained -

! borated water volume in the Boric Acid Storage; System ~ during l' refueling from 2900 gallons to-3200 gallons. The post-LOCA hot _ leg-switchover time is reduced from 13.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to 10.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> due to the

! increased boron concentration.

I- The proposed changes will be implemented in Unit . 2 during its -

t refueling outage _at the end of the current' cycle .(Spring,- 1993)'.

! Implementation in Unit 1 will occur during its refueling outage at f the conclusion of cycle 5 (Spring,.1994). A set of changes to both the Technical ~ Specifications and the: South Texas Project Updated i

Final Safety. Analysis Report during'. the " Unit 2- Only.

Implementation" and the " Final-Implementation" are proposed.

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! To accommodate the above changes, the following changes to the Technical Specifications are proposed:

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a. Specification 3.1. 2. 5 ' is revised to reflect- the proposed-change of the ' required minimum contained borated-water volume F in_the Boric Acid-Storage Tanks during shutdown; i b. Specification 3.1. 2. 5 is revised to . reflect the - proposed change of the required soluble' boron concentration range-in l- the RWST during shutdown and refueling;- . _
c. Specification 3.1. 2. 6_ is - revised - to _ reflects the proposed l change of the required. soluble boron concentration range in L the RWST.during. operation;-
d. Specification 3.5.1 is revised to. reflect the proposed change l?

! of-the required soluble boron concentration range.in-the.SI

' Accumulators; l

e. Specification 3.5.5 is revised to reflect the proposed; change of . the . required soluble boron concentration range . in the -)
i. RWST;- _l l- f. Specification 3.9.1 is revised to reflect the_ proposed change l

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-of the-required minimum soluble boron concentration range--in.

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the reactor coolant. system and refueling- canal- in-- Mode.' 6; i and, i g. The Bases for-Specifications-3.1.2'and 3.9.1lare revised to' reflect the above changes.

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! ST-HL-AE-4281 Page 4 of 9 safety Evaluation for the Proposed Revision to the j Refueling Water Storage Tank and SI Accumulators Allowable Boron Concentration Ranges

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! These changes are shown on the marked-up Technical Specification.

I section(s) in Attachment 3 for the Unit 2 implementation and Attachment 5 for the final implementation.

! Accordingly, the following chanoes to the Updated Final Safety

', Analysis Report (UFSAR) are prcpused:

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a. Section 6.3.2.4 is revised to reflect the proposed change to i the post-LOCA hot leg switchover time;
b. Table 6.3-1-is revised to reflect the proposed change of the required soluble boron concentration range in both the SI Accumulators and the RWST; i c.' Tables 6.5-3 and 6.5-4 are revised to reflect the proposed i change of the required soluble boron concentration range in
both the SI Accumulators and the RWST; i d. Cection 9.1.4.2.2 is revised to reflect-the proposed change of the required soluble boron concentration in the refueling j canal water during refueling operations;
e. Table 9.1-4 is revised to reflect the proposed-change of the required minimum boron concentration in.the spent-fuel pool;

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j. f. Table 9.3-9 is revised to reflect the proposed change of_the i minimum amoupt of boric acid' solution required in the Boric Acid Storage Tanks during shutdown.

! These changes are shown on the marked-up sections of the Updated l Pinal Safety Analysis Report in Attachment 4 for . the Unit 2 implementation and Attachment 6 for the final implementation.

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4.0 Safety Evaluation i*

The purpose of this section is to discuss the impact of the i proposed change on the design andLlicensing basis of'the plant.

Reference 6.1 documents the evaluations presented in sections 4.1:

through 4. 7, . below. The proposed . changes were ' reviewed i with 3 respect to the following technical areas:  ;

L -l l- LOCA-related. analysis Non-LOCA transients

.LOCA mass and energy releases j l

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l Attachment 1 ST-HL-AE-4281

Page 5 of 9 1

Safety Evaluation for the-

. Proposed Revision to the Refueling Water Storage Tank and SI Accumulators Allowable Boron Concentration Ranges j

Post-LOCA sump solution pH Steam generator tube rupture

. Instrumentation and Chemistry Considerations

' Fluid systems design Refueling Criticality Limits l Impact of Cold Weather Operation Each of these areas is discussed below.

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I 4.1 LOCA-Related Analysis (UFSAR Sections 6.3.2.4 and 15.6.5]

4 No credit is taken for boron concentration in the core for the LOCA

- ECCS analysis for either large or.small. breaks. Thus, LOCA ECCS?

. analyses are unaffected by the boron concentration in the RWST and SI Accumulators.

Only the post-LOCA subcriticality and post-LOCA boric acid

l. precipitation calculations following a LOCA in UFSAR Section 15.6.5 j could be affected by this proposed change. With regard to post-

! LOCA subcriticality, the reactor must remain shutdown by borated ECCS water. Since credit is not taken for the control rods in large break LOCA, the borated ECCS water from-the RWST and the SI-

, Accumulators must have a concentration such that, when mixed with i other sources of water, will result in the reactor core-remaining

! subcritical assuming all control-rods-withdrawn.- Increasing the l boron concentration would tend to make the reactor more

! subcritical', as compared to the current analysis- of~ record.

l Therefore, the current analysis is conservative with respect to the i proposed change. This conclusion is confirmed- with each fuel l reload through the normal reload evaluation process.

L The increased' SI Accumulator and RWST ' boron concentration was evaluated . with- respect- to the pot'ential- for boric acid precipitation. _ This evaluation considered. a maximum boric acid-concentration of 3000 ppm in the RWST and the SI Accumulators and 2800 ppm in the rector coolant system (RCS). The results of the.

evaluation show :Lhac the maximum allowable boric acid concentration of 23.53 weight percent (the solubility limit less 4 - weight percent) will not be exceeded in the vessel if hot leg injection is L initiated 10.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> after the inception of a LOCA.- This is a reduction from the current analysis of record which specifies a

time of 13.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

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Y f Attachment 1 ST-HL-AE-4281 Page 6 of 9 safety Evaluation

} for the Proposed Revision to the

! Refueling Water Storage Tank and SI Accumulators j Allowable Boron Concentration Ranges i

i j 4.2 Non-LOCA Transient Analysis j (UFSAR Sections 15.1 through 15.6.1)

Engineered Safeguards Features such as the safety injection (SI) i system and -SI Accumulators are actuated to mitigate the
consequences of the following non-LOCA events

[ UFSAR Section 6.2.1.4 Mass - and Energy Release Analysis for

! Postulated Secondary System Pipe Ruptures Inside Containment UFSAR Section 15.1.4 Inadvertent Opening of alSteam Generator

Relief or Safety Valve Causing .a l Depressurization of the Main Steam System i

f UFSAR Section 15.1.5 Spectrum of Steam System Piping Failures i Inside and Outside Containment i

l The minimum RWST and SI Accumulator-boron concentrations currently j in the Technical . Specifications- are assumed in the analysis of i record for each of these events. For the events analyzed ' in j Sections 15.1.4 and 15.1.5, the analysis criterion is based upon -

l meeting DNB. limits. The current analyses of record do meet the DND.

+ limits. Boron is used to mitigate reactivity. excursions in these-transients and as such, a_ higher concentration of boron only acts-to improve the results of these transients'.- ForJmass-and' energy release-transients, mass and energy can be affected by return to power. Since' increased boron concentrations-result in less core

reactivity this would -result in slightly lower mass and . energy-
j. -releases as compared to-the: current analysis of record.

$ 4.3 LOCA Mass and Energy Releases (UFSAR Section 6.2]' -

l  : Increasing boron concentration levels for the SI Accumulators and

, RWST does not adversely affect LOCA short. term!or long term mass and energy release analysis. These changes - do not affect the-4- normal plant operating 1 parameters, system actuations, accident _

1 mitigating capabilities or assumptions-important to the LOCA mass

{ and energy release analyses or create conditions lmore limiting than

[ those considered in ' the ' analysis of record. Total delivered-C

. injection ~ flow -is :the- critical characteristic- of the --SI

-Accumulators and RWST for these analyses. Therefore,- the i conclusions presented in.the UFSAR remain valid with respect to these analyses with the implementation of1the proposed. change in j boron concentration.

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Attachment 1 ST-HL-AE-4281 Page 7 of 9 Bafety Evaluation for the Proposed Revision to the Refueling Water Storage Tank and SI Accumulators Allowable Boron Concentration Ranges i

4.4 Post-LOCA Sump Solution pH (UFSAR Section 6.5.2)

The current Technical Specifications assure that the recirculation fluid pH control system contains sufficient trisodium phosphate to a raise the pH of the sump solution in the range of 7.0 to 9.5. The existing analysis of record for the sump solution pH falls within the acceptable range. Additional analysis has confirmed that with the proposed changes to the SI Accumulator and RWST boron concentrations, the acceptable sump solution pH range continues to be met. In addition, the sump pH remains within the range used in the analysis of the iodine spray removal effectiveness.

, 4.5 Steam Generator Tube Ruptute (UFSAR Section 15.6.3]

The Steam Generator Tube Rupture (SGTR) analysis conservatively models margin to overfill and offsite radiological consequences.

The current analysis meets the criteria for margin to overfill and offsito doses are a small fractio.4 of the guidelines presented in 10 CFR Part 100. SI Accumulator injection does not occur in a SGTR event and thus the accumulators' boron concentration has no effect on SGTR analysis results. However, SI injection from the RWST does occur. The increased baron concentration in the RWST reduces the reactivity of the core and does not have an adverse effect on the

, SGTR analysis results.

4.6 Instrumentation and Chemistry Considerations Based on an evaluation of the post-accident chemistry, conditions expected in the containment following a design basis LOCA or steamline break fall within acceptable ranges. Thus the assumptions and conclusions of the equipment qualifications /

chemistry evaluations documented in WCAP-12861 (Reference 6.2) are unaffected. The RCS chemistry will continue to be controlled according to the guidelines provided in UFSAR Section 5.2.3.2.1.

4.7 Fluid Systems Design The impact of the change in SI accumulator and RWST boron concentration on auxiliary fluid systems have been reviewed. A change to the Boric Acid Storage Tank volume for Mode 6 is required in order to meet the Mode 6 reactor coolant system concentration requirements. This is based on a reasonable value of 2800 ppm which is expected to bound future cores. The current boration requirement is 1600 gallons (2900 gallons contained, 1300 gallons unusable). For Unit 2, cycle 4, the value required is 1880 TSC\92-343.001

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Safety Evaluation i for the Proposed Revision to the Refueling Water Storage Tank and SI Accumulators Allowable Boron Concentration Ranges i

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! gallons. The Technical Specification value of 2900 gallons should i be revised to 3200 gallons (1300 gallons unusable +'1880 gallons -

for boration requirements). There is no tank level setpoint associated - Lwith this volume. The volume change will have no

{_ adverse effect on auxiliary fluid systems.

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i. The SI Accumulator - volume-and setpoints are. unaffectedJ by the

{ proposed enange. Also, no change was made to-the volume of the i RWST or to the operating temperature range of the RWST.

l- The performance of the Chemical and Volume Control System-(CVCS),

Emergency Core Cooling System (ECCS), and Containment Spray. System j (CSS) are- not adversely affected by the. -proposed . boron-l concentration changes, since - there are no changes to the - flow resistance characteristics of the pumps-or injection paths. . The j Residual Heat Removal System (RHR) performance is unaffected by the j proposed change.

! 4.8 Refueling Criticality Limits 1 The proposed change in - the minimum boron concentration in the i reactor -coolant. system and refueling canal during refueling i operations allows. greater core design flexibility for Beginning of-z i Life conditions. To minimize problems,-cores are usually designed

to meet the K limit of'less than or equal to 0.95 at-a boron concentration wh .,,ich is less than the minimum specified'in Technical
Specification 3.9.1, rather than specifying a boron-concentration

, which is greater than- the ' minimum allowed. Although . in' either design .the K,,, limit would still be met. In order to continue this-1 philosophy, an l increase of the minimum boron concentration is-needed to allow more reactive coree to be-designed and loaded while i, still' meeting the 0.95.K,,, limit for-reactivity.

l 4.9' Impact of Cold Weath'er Operation i

j The impact of cold weather operation on the' systems containing the j increased - soluble boron has been evaluated.- The fluid systems

! involved are contained within the mechanical- auxiliary building'and reactor containment building. The minimum temperatures for the two-buildings are- greater than that which- would causef boron-precipitation in a 3000 ppm boron solution.

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safety Evaluation for the-l Proposed Revision to the

. Refueling Water Storage-Tank and SI Accumulators j Allowable Boron concentration-Ranges 1

1 5.0 Conclusion i

! The proposed changes to the UFSAR and Technical-Specifications,:as

! described above, are acceptable because the increases in the= boron-j concentrations-in the SI accumulators, RWST, and refueling canal,.

j- and the changes in required volume of the Boric Acid StorageLTanks

do not pose a- significant increase in hazard or -involve a a

significant reduction in a margin of safety.- HL&P requests approval of the proposed changes.

! 6.0 References 6.1 " Implementation of RWST and SI Accumulator Boron

{ Concentrations", Letter .from R.C.- Cobb, Westinghoues

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Commercial Nuclear Fuel- Division, to D.F. Hoppes, Houston i Lighting and Power, dated 11/18/92, ST-UB-HL-1187.

!- 6.2 " Spray Additive Deletion-Chemistry Impact to Qualification'-

of Westinghouse Supplied Class 1E Equipment", March 1991,

' WCAP-12861.;

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, TSC\92 343.001'

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n ATTACHMENT 2 i

i No Significant Hazards Evaluation for the Proposed Revision to the Refueling Water Storage Tank and SI Accumulators Allowable Boron Concentration Ranges 1

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2 TSC\92 343.001 i

4 Attachment 2 ST-HL-AE-4281 Page 1_of 3 No Significant Fr ards Evaluation  ;

fo- .no i Proposed 5 1sion to the Refueling Water Stor J Tank and SI Accumulators Allowable Borta Concentration Ranges Pursuant to 10CFR50.91, this analysis provides a determination that the proposed change to the Technical Specifications does not involve significant hazards considerations as defined in 10CFR50.92.

(1) The proposed change does not involve a significant increase in the-probability or consequences of an accident previously evaluated.

The proposed increase in boron c;ncentrations increases the amount of boron delivered to the teactor core under accident-conditions. This will decrease the reactivity of the core and will not increase the probability or consequences of an accident previously evaluated.

The reduction in the switchover time for the post-LOCA hot leg injection will ensure that the maximum allowable boric acid concentration will not be exceeded, thus maintaining the current margin to safety.

The proposed increase in the required volume of the Boric Acid Storage Tanks is to ensure that suf ficient-boric acid is available to borate the reactor coolant system and the water in the refueling canal such that-the criticality limit during shutdown and refueling'can be met for future cores.

The increase in the required minimum boron concentration in-the refueling canal in Mode 6 does not modify or_ replace the Kg reactivity limit.- The design of each reload core is checked to ensure that the refueling criticality limit is met.

Therefore, the changes do not involve a .significant _ increase in the probability or consequences of an accident previously evaluated.

(2) The proposed change does not create the possibility of a new or different kind of accident from_any accident previously-evaluated.

TSC\92 343.001

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Attachment 2 L ST-HL-AE-4281 '

l Page 2 of 3 5 No Significant Hazards Evaluation for the

! Proposed Revision to the j Refueling Water Storage Tank and SI Accumulators

Allowable Boron concentration Ranges
The proposed increase in boron _ concentrations increases-the amount of boron delivered to the reactor core under accident conditions. This increase in boron will not create the possibility of a new or different kind of accident from any accident previously evaluated.

j The reduction in the switchover time for the post-LoCA hot

! leg injection will ensure that the maximum allowable boric acid' concentration will not be exceeded. This reduction in i switchover time will maintain the current margin to safety.

l Therefore, the increase in the boron concentration will not-l create the possibility of a new or diff erent kind of accident from any accident previously evaluated.

! The proposed increase in the required volume of the Boric j Acid Storage Tanks during shutdown and refueling is to ensure

the reactor _ coolant system can be adequately borated during i shutdown. This increase in volume does not create the i possibility of a new or different kind of accident from any accident previously evaluated.

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! The increase in the required minimum boron concentration in

_ the refueling canal in Mode 6 does not modify or replace the l K g, reactivity limit. Therefore, the increase in the boron 4

concentration will not create the possibility of a new or i different kind of accident- from any_ accident. previously 3 evaluated.

! The proposed changes do not create the possibility of a new.

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or different kind of accident from any accident _previously

evaluated.

t (3) The proposed change does not involve a.significant_ reduction 3

in a margin of safety.

The proposed increase in boron concentrations increases the

amount of boron delivered to the reactor core under accident l conditions. This will decrease the-reactivity-of the-core and will not cause a decrease in a margin of safety.

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TSc\92 343.001 -

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j -Attachment _2 d

ST-HL-AE-4281

Page 3 of 3 i-No Significant Hazards Evaluation 2

for the 4 Proposed Revision to the j- Refueling Water Storage Tank and SI Accumulators Allowable Boron Concentration Ranges-l i

The reduction in the switchover time for the post-LOCA L hot

leg injection will ensure that the-maximum allowable boric-I acid concentration will not be exceeded, thus maintaining the i current margin of safety.. .

3 The proposed increase in the required volume of the Boric j Acid Storage Tanks is.to ensure that sufficient boric acid is j available to borate the water in the reactor coolant-system-and the ? refueling canal such that the criticality limit' during shutdown and refueling can be met for future cores.

. Also, the ' increase in the. required minimum boron

! concentration in the refueling canal in Mode '6. does not

! modify or replace the K g-reactivity limit. The_ design of each reload core is chNcked to ensure that the ' refueling criticality limit is met. .The proposed changes do not -

l- involve a change to the refueling criticality limit and serve 1 to maintain the current margin of safety.

l. Therefore, the proposed changes do not--involve a significant i reduction in a margin of safety.

l-i The proposed changes to the Technical Specifications are acceptable

, because the they-_do not pose a significant increase in' hazard or

-involve a significant reduction - in a margin af - safety.
HL&P.

requests approval of the proposed changes. ,

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