ML20115E746

License Amend Request 92-06 to License NPF-87,revising TS to Increase Boron Concentrations for Refueling Water Storage Tank & ECCS Accumulators

ML20115E746
Person / Time
Site:	Comanche Peak
Issue date:	10/19/1992
From:	William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20115E749	List: ML20115E746 ML20115E811
References
TXX-92469, NUDOCS 9210220103
Download: ML20115E746 (12)

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$ e M Log # TXX-92469 ll""" ':::T:ll File # 916 (3/4.1)

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916 (3/4.9) clo 10010 7UELECTRIC Ref. # 10Crns0.90 10CFR50.36 wmi.im J. cant. Jr. October 19, 1992 n,.i. v,. e rm.am V. S. Nuclear Regulatory Commission Attn: Document Cont rol Desk Washington, DC 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC 5 TAT 10N (CF5CS)- UNIT 1 DOCKET N0. 50-445 SUBMITTAL OF LICENSE AMENOMENT REQUEST 92 06 INCREASE IN RWST AND ACCUMULATOR BORON CONCENTRATION Gentlemen:

Pursuant to 10CFR50.90, TU Electric hereby requests an amendment to the CPSES Unit 1 Operating License (NFP-87) by incorporating the attached changes into the CPSES Unit 1 Technical Specifications, in general, the proposed changes revise the CPSES Unit 1 Technical Specifications by increasing the boron concentrations f or ibc Ref ueling Water Storage Tan 6 and the Emergency Core Cooling System (ECCS)

Accumulators. These changes support operation with extended fuel cycles (currently planned f or Cycle 4). Attachment 2 prov. des a detailed description of the proposed changes, a safety analysis of the changes, ard TU Electric's determination that the proposed changes do not involve a significant hazards consideration. Attachment 3 provides th.s affected Technicai Specification pages (HUREG 1399), marke.1 up to reflect the proposed changes.

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Since Cycle 4 operation is presently scheduled for December, 1993, TV Electric requests NRC review and approval of thrse changes no later than September 30, 1993, to support refueling operations, TV Electric requests that the approval transmittal for this proposed amendment identify an implementation period which starts following the shutdown for Cycle 3 and ends prior to the startup for Cycle 4, as required by the Cycle 4 reload safety evaluation, i

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9210220103 921019 l l PDR ADOCK 05000445 " R olin S'r"' LB.81 Dalla $.Texa$ 7520 P pop < '

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T X X - 9 24(.9 Page 2 of 2 In accordance with 10CFR50.91(b). TV Electric is providing the State of lexas with a copy of this proposed amendment.

Should you have any questions, please contact Mr. Jimmy D. Seawright at (214) 812 4375.

Sincerely,

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William J. Cahill, Jr.

JDS/grp Attachments: 1. Affidavit

2. Description and Assessment

3. Affected Technical Specification pages (NUREG 1399)

Enclosures:

1. Westinghouse Safety Evaluation, ' Plant Operation at a Modified Primary Coolant Chemistry pH Regimen,'

SECL-92-235.

2. NUREG-0800 Standard Review Plan, Section 6.5.2, Rev. 1 July 1981.

3. NUREG 0B00. Standard Review Plan, Section 6.5.2, Rev. 2 - December 1988.

4. Techiical Specificationt, South Texas Project Units No I and No. 2. Title Page and Page 3/4 5-10 J. Federal Register 48FR14870 Vol . 48 N067 c- Mr. J. L. Hilhoon, Region IV Hr. B. E. Holian, NRR Mr, 1. A. Bergman, NRR Resident inspectors, CPSES (2)

Mr. D. K. Lacker Bureau of Radiation Control Texas Department of Public Health 1100 West 49th Street Austin, Texas 78704

Attachment I to TXX 92469 Page 1 of 1 l

UNITED STATES OF AMERICA I NUCLEAR REGULATORY COMMISSION l i

In the Matter of )

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Texas Utilities Electric Company ) Docket Nos. 50-445

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(Coman;he Peak Steam Electric ) License No. NFP-87 Station, Unit 1 ) )

AFFIDAVIT William J. Cahill, Jr. being duly sworn, hereby deposes and says that he is Group Vice President, Nuclear of TV Electric, the lead Applicant herein:

that he is duly authorized to sign and file with the Nuclear Regulatory Commission License Amendment Request 92 06, concerning boron concentration changes for the RWST snd the ECCS Accumulators; that he is familiar with the content thereof; and that the matterr set forth therein are true and correct to the best of his knowledge, information and belief.

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William J. Mhill, Jr.

Group Vice President. Nuclear STATE OF TEXAS )

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COUNTY OF 6* M %

Subscribed and sworn to before me, on this [ day of 0 0 70 d'% /ffA

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j Attachment 2 to TXX-92469 j Page 1 of 9 t

l- SIGNIFICANT RAZARDS CONSIDERATION j PROPOSED CPSES UNIT 1 TECHNICAL SPECIFICATTON CHANGE i

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l 1. BACKGROUND i

The intent of these changes is to allow for higher boron concentrations for the fluids in the Refueling Water Storage Tank (RWST) and Emergency Core Cooling . System ; (ECCS)

Accumulators. This' increase in boron concentration is j neesssary to accommodate shutdown margin and safety analysis j requirements associated with 18 month reload cycles. Other system aspects may also be'affected by the proposed move to j- exte.nded cycle designs. In addition, .the impact _on primary j system components of operating the fuel cycle with increased

boron concentration has alsoLbeen evaluated.

4 j The higher boron concentration requirements during-the~early I j portion of the extended fuel cycles could af fect the basis  ;

for the Fr.ergency Boration System,= the basis for the 30 gpm I boration flow rate requ'rement in Tech Spec 3.1.1.1 and.

4 3.1.1.2, and the required volumes in the Refueling: Water j Storage Tank (RWST) L and ?oric Acid Storage LTank :(BAST) . In-addition, core performance restraints _ described in the Core- -

Operating Limits Report as well as other safety-related i parameters could also be affected.

i j For each cycle of operation, the validity of the existing safety analysis is reconfirmed-or axre-analysis is-i performed. Such a cycle-specific analysis-is-documented in j the Relcad Safety Evaluation.

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4 II. DESCRIPTION OF TECHNICAL' SPECIFICATION CHANGE' REQUEST 4

4-The proposed-changesErevise Technical-Specificationc~

4 3/4.1.2.5, 3/4.1.2.6, 3/4.5.1, 3/4.5.4,-and 3/4.9.1, and the

}- BASES-for 3/4.1.2, 3/4.5.4,Jand-3/4.9.1. The changes _

increase the boron concentration ~of the fluid-in the RWST to

}- the range of 2400 to 2600. ppm and the ECCS' Accumulators to the' range of.2300 to 2600_ ppm.

These changes enable the-use of extended reload cycles.

.Specifically, T/S 3/4.l.2.5,- 3/4.1'.2.6:and 3/4.5.'4-are '

t revised'to' increase the minimum boron concentration for the j kWST from 2000 to 2400 ppm.. In addition,.3/4.1.2.6 and 3/4.5.4 are revised to increase the maximum boron-concentration for the RWST from 2200 to 2600.

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Attachment 2 to TXX-92469 Page 2 ot' 9 T/S 3/4.5.1 is revised to increase the allowed boron j concentration range for the ECCS Accumulators from 1900-

! 2200 ppm to 2300-2600 ppm.

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T/S 3/4.9.1 is revised to increase the minimum boron 3

concentration during refueling operations for the Reactor l Coolant System (RCS, and the refueling canal from 2000 ppm j to 2400 ppm. j 4

i T/S BASES 3/4.1.2 is revised to reflect the increased 1 minimum boron concentration for the RWST.

4 T/S BASES 3/4.5.4 is revised to reflect the slight decrease l in the minimum equilibrium Containment Sump solution pH (8.5 )

to 8.25) that results from the increased acidity of the more l I

highly borated solutions.

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T/S BASES 3/4.9.1 is revised to' reflect the increased j minimum boron concentration during refueling operations for the RCS and the refueling canal.

III. ANALYSIS The changes to the CPSES Technical Specifications associated

! with this submittal involve an increase in the boron

, concentration of various fluids. Specifically, chey

, includet (1) increasing the RWST boron concentration to the range of 2400-2600 ppm, (2) increasing the Emergency Core Cooling System (ECCS) Accumulator boron concentration to the range of 2300-2600 ppa and (3) increasing the minimum refueling operations boron concentration to 2400 ppm.

l The increased boron concentration provides core designers

with necessary flexibility for designing reload configurations for 18 month reload cycles. The increased boron concentration enables the design of such cores while complying with the various safety analyses requirements.

The increased boron concentration could impact CPSES in several ways.- Reviews were performed for these various impacts and are summarized below. However, specifically excluded from this process is consideration of.the ability i

of any specific core design to comply with the safety-related design requirements. Compliance with such requirements will be demonstrated during the normal reload analysis procese.

The increased boron concentration will result in fluid

-- chemistry changes. Some equipment may therefore be exposed to an environment different, and potentially more limiting, than that for-which it had previously been evaluated.

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Attachment 2 to TXX-92469 l Page 3 of 9 '

Equipment could be subjected to in-line exposure (piping, valve internals), exposure to containment spray (in-containment equipment) and/or exposure to High Energy Line Break (HELB) sprays.

With rospect to the in-line exposure of equipment, these ,

components are composed of materials which have been previously qualified for boron concentrations up to 2200 ppm. A review of the general chemistry pr operties of the slightly higher boron concentration fluid indicates no mechanism that would result in an appreciable increase in the in-line component failure rate. While the corrosive nature of the fluid will increase, .this increase will be only minimal.

It has been determined that a modified lithium control program provides an acceptable coolant pH range during power nparation. Operation in the specified chemistry regimen is concluded to be acceptable for system chemistry and corrosion control. The impact on steam generator tube stress corrosion cracking has been assessed and plant specific fuels and material reviews have been performed. It is concluded that operation with a modified lithium control program in conbination with increased boron concentrations will~have no adverse effect on the reactor core and associated ope.;ating systems (Reference 1) .

For components located inside containment, and thus exposed to containment spray effects, the critical consideration is the pH of the containment spray. The Containment Sump pH l and Spray pH were recalculated using the plant design basis i

fluid system operating scenarios, but with the higher boron concentration. The revised calculation indicates that with the ir.:reased boron concentration, the range in pH' extremes is smaller. However the calculation did identify that the minimum equilibrium-Containment Sump pH willEbe approximately 8.25, as compared to the_ current minimum pH of 8.5. This small decrease does.not result in a significant change in evaluated equipment performance.

With respect to the impact of HELB sprays, the review results are the same as those for_the in-line component review. The chemical nature of the 2600 ppm borated fluid is not appreciably different from the' of 2200 ppm borated fluid. There are no mechanisms which_would result in any substantial increase in the sprayed equipment failure rates.

The impacc of the decrease in the minimum pH of the containment sump and spray on the radioisotope retention characteristics has been evaluated. The minimum equilibrium i

sump pH of 8.25 is slightly below the minimum value

Attachment 2 to TXX 92469 Page 4 of 9 considered in Section 6.5.2 of the Standard Review Plan, Revision 1 (Reference 2). A review of the design basis for CPSES indicated that the decontamination factor for off-site dose consequences wea assumed to be 100. Due to CPSES characteristics, an iodine partition factor' of approximately 5000 is consistent with this decontamination factor. Based upon tne guidelines of reference 3 and a review of the CPSES design bases, it was determined that the assumed partition factor of 5000 will continue to be valid with the new boron concentrations and the slightly lower pH. Thus, the radiological consequences of the calculated decrease in the minimum equilibrium sump pH are bounded by the current CPSES design analysis.

The impact of the Containment Spray, with a lower pH equal to 8.25, upon the combustible gas production rate was also  !

evaluated. No mechanism for-increased combustible gas production was identified. i The Emergency Boration System ie required to deliver a sufficient flow of a sufficiently borated fluid-in order to bring the plant from hot full power conditions, equil " '

xenon to hot stand by, 1% shutdown (k g, < 0. 99) , over e minute period, and then to compensate for the complete ducay of the xenon over the subsequent 90 minute period.

Calculations have been performed to verify that the bases remain valid. Boron worths and boron concentrations which are expected to bound future reload cycles were considered in this evaluation; however, the centinuing applicability of the evaluation must be reconfirmed on a cycle-specific basis.

The bases for Technical Specifications 3.1.14 1 and'3.1.1.2 indicate that 30 gpm of fluid with a boron concentration y

greater than 7000 ppm is to be used to compensate for the maximuu. yenon burnout rate. Calculations have been performed t; verify that the bases remain valid. Boron worths and boron concentrations whien are expected to bound futuro reload cycles were considered in this evaluation; however, the continuing applicability of the evaluation must be_ reconfirmed on a cycle-specific basis.

The bases for the required RWST and BA3T volumes, shown in Section 3/4.1.2 of the BASES, have also been reviewed.

Although values of key parameters have been used in-the affected calculations which are expected to bound future (

cycles, the continued validity of thesa volumes must be I reconfirmed on a cycle-specific basis.

Becaure of the increased boron concentration, post-LOCA

, boron calculations:were performed to determine thelpost-l 1

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LOCA sump boron concentration conservatively using the minimum boron concentrations of the contributing water  ;

3 sources. The calculations demonstrated that the post-LOCA  ;

sump boron concentration is adequate to koop the reactor suberitical during post-LCCA long term cooling.

Furthermore, calculations were performed to determine the i time at which switchover is required for the initiation of hot leg recirculation phase to assure boron solubility i within the core. Boron worths and boron concentrations

! which are expected to bound future reload cycles were

! considered in this evaluation, however, the continuing

applicability of the evaluation must be reconfirmed on a cycle-specific basis.

The boron solubility limit at 35'F coolant temperature is i 4900 ppm. An increase in the boron concentration to 2600 i ppm will not cause crystallization of the RWST contents because Technical Specifications require the RWST

{ temperature to be no less than 40*F.

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The accident analyses have been reviewed to assess the impact of the increased RWST boron concentration. The

, inadvertent actuation of the ECCS event, described in FSAR

Section 15.5.1, could be cdversely affected. This event is

analyzed to demonstrate that the minimum DNB ratio remains i

! greater than the acceptance limit. As currently noted in 1

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the.FSAR, the DNB ratio increases from its initini value throughout the event. The increased RWST boron

concentration, and thus, the increased ECCS fluid boron i

concentration, will affect the timing of the sequence of events; however, es concluded in the current FSAR, the time at which reactor trip occurs is of little concern for this transient. Based on the current evaluation of this event, j no changes in tne event consequences are anticipated; ~

however, the continued validity of this conclusion-wil1 be

reconfirmed on a cycle-specific basis.

In License Amendment 10 to the CPSES Unit 1 Technical l Specifications, the requirements for the operability of the i Boron Dilution Mitigation System were' waived while the adequacy of the system and the methodology for'the analysis

^ of the inadvertent boron dilution event were being investigated. This waiver expires _six months after Cycle 3 criticality. Thus,_this isaue will be addressed prior to j the start of Cycle 4 operation.

' The transition to the extended cycle will not affect the conclusions of the inadvertent boron dilution event analysis, regardless of the final analytical methodology.

As is the case for all reloed safety evaluations, the parameters which could affect the conclusions of the

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Attachment 2 to TXX-92469 Page 6 of 9 inadvertent boron dilution event are evaluated on a cycle specific basis for continued applicability. If necessary, the event is reanalyzed with the revised values of key safety parameters. If required, additional restrictions, such as increased shutdown margins, mry be imposed to ensure that the applicable event acceptance criteria will be sacisfied.

In conclusion, as a result of the reviews conducted regarding the effect of the increased boron concentrations, ,

no significant impact was identified. ~

IV. SIGNIFICANT HAZARDS CONSIDERATION DETERMIHhTION Tn Electric has evaluated the significant hazards consideration involved with the proposed change by focusing on the throe standards set forth in 10 CFR 50.92 (c) as diccussed below:

Does the proposed change:

1. Involve a significant increase in the probability or consequences of an accident previously evaluated?

The proposed changes are related to the boron concentration in the RWST anc ECCS Accumulators. This

, increased concentration does not constitute a change expected to increase the probability of a previously evaluated accident. The means by which the proposed changes might result in increased radiological consequences of various accidents are discuosed below.

The first mechanism is that the higher boron concentrations may result in increased probability of equipment failure that is, in-containraent or in-process equipment taing exposed to an environment more severe t!.an that to which it is qualified. A review indicates that no significant impacts result from this mechanism. Thus there is no significant increase in the consequences of any accident due to an increase in the probability of equipment failure.

The second mechanism is that the changes in containment spray and sump solution pH may change the radioisotope removal and partition characteristics. 'A review indicates that while-the relevant characteristics are affected, the resulting limiting coefficient values associated with the pH changes are bounded by the values used in CPSES design calculations. Thus, no adverse impact on the radiological consequences arising from this mechanism has been identified.

Attachment 2 to TXX-92469 Page 7 of 9 Another mechanism for affecting the radiological consuquenco is the change in Containment Spray and Sump solution pE which may change the containment combustible gas profile. A review of this phenomena concluded that there-is no significant increase in the >

containment combustible levels; thus there is no significant increase in the consequences of any accident previously analyzed.

The higher boron concentration could have an adverse impact on th:r inadvertent actuatien of the ECCS event.

Althouth the timing of the sequence of events may be affected, the DNB ratio continues to increase from its initial value throughout the event. Based on a review of this event, no changes in the event probability or concenquences are anticipated; however, the continued validity of this conclusion will be reconfirmed on a cycle-specific basis.

2. Create the possibility of a new or different kind of accident from any accident previously evaluated?

The proposed change is a passive change-associated with fluid boron concentration. No new or different accident sequences have been identified. Furthermore, a review of heat tracing requirements indicates that there are no additional' requirements resulting from the boron concentration increase. There are no previously unconsidered failure mechanisms.

3. Include a significant reduction in the margin of safety?

The decrease in the containment spray and sump solution pH could be expected to result in higher airborne iodine concentrations. The accident source terma could be impacted by variations in the iodine spray removal and partition factors. A comparison of the coefficients for the minimum equilibrium containment sump solution pH'to those used-in the CPSES design analyses, indicated that the expected. coefficient values would remain bounced by the values used'in the previous anelyses. Thus, no significant reduction in the margin of scfety has been identified as associated with this phenomana.

t I Attachment 2 to TXX-92469 Page B of 9 The parameters contained in the Technical Specifications for which the~ changes are requested are used when performing design analyses. .In particular, these parameters are used for confirming compliance of the core design with'the requirements. The changes requested are therefore not in themselves sesociated with any significant decrease in the margin of safety in regards to the Chapter 15 analyses.

The commission has provided some guidance concerning the application of the standards for determining whether a significant hazards consideration exists, by providing certain examples (48 FR 14870 - Ref. 5) of amendments that are considered.not likely to involve a significant hazards consideration.

These changes fall under example (vi), a change that may result in some increase to the consequences of a previously analyzed event, but where the change is within acceptable criteria. It is noted that Reference 3 allows Sump Solution pH within the range 7.0-10.5 with regards to the mitigation of radiological consequences of an accident.

Based on the above evaluations, TU Electric concludes that the activities associated with the proposed changes satisfy the no significant hazards consideration standards of 10CFR50. 92 (c) and, accordingly, a no significant hazards consideration finding is justified.

V. ENVIRONMENTAL EVALUATION TU Electric has evaluated the proposed changes and has determined that the changes do not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increaJe in the amount of any effluents that may be released off-site, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed change moets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22 (c) . Therefore, pursuant to 10 CFR 51.22 (b) , an 4

environmental assessment of.the proposed change is not required.

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Attachment 2 to TXX-92469 Page 9 of 9

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! VI. REFERENCES 4

) 1. Westinghouse Safety Evaluation, " Plant Operation at a Modified Primary Coolant Chemistry pH Regimen,"

SECL-92-235.

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2. Standard Review Plan 6.5.2 Rev. 1, " Containment Spray as a Fission Product Cleanup System".

) 3. Standaro Review Plan 6 7.2 Rev. 2

[ "Containm9nt Spray as a Fission Product Cleantip System" 1

4, NUREG 1346, Technical Specifications South Texas.

4 Project, Unit Nos. 1 and 2, Appendix A, License Nos.

i NPF-76 and NPF-80.

i j 5. Federal Register 48 FR 14870 Vol. 48 N067 I

VII. PRECEDENTS There are precedents for operating with an elevated boron concentration in order to support extonded cycle operations.

One example of Technical Specification limits for operation with an elevated boron concentration in the RWST to the range of 2500 to 2700 ppm at South Texas Project Units No. 1 and No. 2 (Reference 4).

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