ML20113G888

Application for Amend to License NPF-3,revising TS 3.1.1.2, Reactivity Control Sys-Boron Dilution & Associated TS Bases 3/4.1.1.2

ML20113G888
Person / Time
Site:	Davis Besse
Issue date:	05/01/1992
From:	Myers T CENTERIOR ENERGY
To:
Shared Package
ML20113G887	List: ML20113G885 ML20113G888 ML20113G890
References
2007, NUDOCS 9205130184
Download: ML20113G888 (7)

Text

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. Docket Number 50-346 License Number NPF-3 Serial Number 2007 Fnclosure

'Page 1 f.PPLICATION FOR AMENDMENT I

T0 i -CILITY Ci'ERATING LICENSE NPF-3 DAVIS-BESSE NUCLEAR POVLR STATI0h UNIT NUMBER 1 S

Otached are requested changes to the 6 avis-Besse Nuclear Power . ?,

stion, Unit Numbet 1 Facility Operacing License Number NPF-3. Also ' y'

luded is the tafety Assessment and Significant Hazards N.

Consideration.

The proposed chaages (submitted under cover letter Serial Number 2007) concern:

Appendi:s A, Technical Specification 3/4.1.1.2, Reactivity Control Systems-Boron Dilution Appendix A, Technical Specification Bases 3/4.1.1.2, Boron Dilutior.

For: D. C. Shelton Vice President, Nuclear By: m T. . yers D e or - Technical Services Sworn and Subscribed before me this 1st day of May, 1992.

YUll?fhh Y. A IM) '

Notary Ptytille,~ State of Ohio EVELYN L DRESS NOTARY FtEliC, STATE OF OHK)

UmEr;esMy23,1994 9205130194 DR 920501 ADOCK 050007~6 PLR

Docket Number 50-346 License Nucher NPP-3 Serial Number 2007 Enclosure

'Page 2 The following information is provided to support issuance of the requested changes to Davis-Besse Nuclear Power Station, Unit Numbet 1

) Operating License Number NPT-3, Appendix A, Technical Specification (TS) 3.1.1.2, Reactivity Control Systems-Boron Dilution, and its associated Bases.

A. Time Required to Implement: This change is to be implemented within 90 days after NRC issuance of the License Amendment.

B. Reason-for Change (License Amendment Request Number 91-0022, Revision 0):

Certain maintenance activities during plant outages may require that the RCS 1cvel be reduced below the level of the reactor Ni$(f(

• 12' - vessel flange. For example, in order to install steam generator nozzle dams, the RCS is drained covn to approximately 18" above

..d the RCS hot leg centerline. At this level, to prevent vortexing 9-@@2S and Decay Heat Removal (DHR) pump cavitation, DHR flow rate is

(;'h( procedurally limited to slightly less than 2800 gpm. In this situation, TS 3.1.1.2 restrictions vould apply. That is, with iwig 33' DHR flovrate belov 2800 gpm any water added to the RCS would be

' required to be of higher boron concentration than the RC3.

In accordance with TS 3.9.1, during Mode 6 (refueling), the boron concentration of all filled portions of the Reactor Coolant System (RCS) and the refueling canal must be maintained uniform and sufficient to ensure that the more restrictive of two reactivity conditions is met keff < 0.95, or boron concentration of > 1800 ppm.

The proposed change to TS 3.1.1.2 vould add a iootnote that provides an exception applicable in Mode 6 (Refueling).

Specifically, with the flow rate of reactor coolant through the -

RCS less than 2800 gpm, the footnote would allow the addition of water of lover boron concentration than the RCS provided that the boron concentration of the water to be aaded is equal to or greater than the boron concentration corresponding to the more restrictive reactivity condition specified in TS 3.9.1. A related change is proposed clarifying Bases 3/4.1.1.2.

C. Safety Assessment and Significant Hazards Consideration: See Attachment

. Docket Number 50-346 License Number NFF-3 Serial Number 2007 Attachment

'Page 1

! SAFETY ASSESSHENT AND SIGNIFICANT HAZARDS CONSIDERATION TITLE:

Revision of Technical Specification (TS) 3.1.1.2, Reactivity control Systems-Doron Dilution, and Associated TS Bases 3/4.1.1.2 to Add an Exception Applicable in Mode 6.

DESCRIPTION:

The purpose of the proposed changes is to modify the Davis-Besse Nuclear Power Station (DBNPS) Operating License NPF-3, Appendix A Technical Specification (TS) 3/4.1.1.2 (Reactivity Control Systems -

Boron Dilution) and its associated Bases.

Technical Specification 3.1.1.2 currently states: "The flow rate of reactor coolant through the Reactor Coolant System shall be 22800 gpm whenever a reduction in Reactor Coolant Systet boron concentration 's being made." As described in TS Bases 3/4.1.1.2, "A minimum flow rate of at least 2800 GPH provides adequate mixing, prevents stratification and ensures that reactivity changes vill be gradual through the Reactor Coolant System in the core during boron concentration reductions in the Reactor Coolant System."

The proposed change to TS 3.1.1.2 adds a footnote that provides an eyeeption applicable in Mode 6. Specifically, with the flow rate of reactor coolant through the Reactor Coolant System (RCS) less than 2800 gpm, the footnote allovs the addition of vater of lower boron concentration than the existing RCS concentration provided that the boron concentration of the water to be added is greater than the boron concentration corresponding to the more restrictive reactivity condition specified in TS 3.9.1, Refueling Operations - Boron Concentration (copy attached). This exception is acceptab), since as long as the boron concentration of the vater to be added to the RCS is equal to or greater than the refueling boron concentration, the resulting RCS boron concentration is assured to remain greater than the required refueling concentration. Therefore, in this situation, even if incomplete mixing did occur, it would be of no adverse safety consequence.

The proposed change to T5 Bases 3/4.1.1.2 adds a discursinn of the proposed Mode 6 exception to TS 3.1.1.2.

Certain maintenance activities during refueling may require that the RCS level be reduced below the level of the reactor vessel flange. As the RCS level is reduced, procedural limits are placed on maximum Decay Heat Removal (DHR) flow rate to prevent vortexing and pump cavitation.

Since the available DHR pump suction pressure decreases as RCS level is decreased, DHR flow rate is procedurally restricted at reduced RCS levels. Reactor Coolant System temperature is closely monitored to ensure that the flow rate is adequate to cemove decay heat. Vith DHR flow rate procedurally restricted to less than 2800 gpm, the proposed change to TS 3.1.1.2 vould result in greater flexibility in the choice of water addition sources when RCS vater addition is necessary.

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. .l Docket = Number?50-346

. . License Number NPF-3 Serial Number 2007 Attachmeat J

'Page'2-SYSTEMS, COMPONENTS,-AND'ACilVITIES AFFECTED: i RCS Boron Dilution in Mode 6 (Refueling)

LSAFETY FUNCTIONS OF THE AFFECTED SYSTEMS, COMPONENTS AND ACTIVITIES:

The TS 3.1.1.2 (Reactivity Control Systems-Boron Dilution) Limiting Condition for Operation (LCO) is based on the requirement to maintain a minimum RCS flow rate in order to provide adequate mixing of the RCS.

Adequate mixing prevents stratification,-and ensures that ceactivity changes vill _be gradual through_the RCS in.the core during boron concentration reductions. A gradual' reactivity changa rate ensures that the boron concentration reduction evolution vill be within the operator's capability to recognize and control.

' Maintaining the boron concentration of all filled portions of the-RCS >

and thej refuelf < canal suf Cicient to meet the more restrictive of the two reactivity conditions listed in TS 3.9.1 ensures that there vill be adequate reactivity control and that the required shutdown margin vill be maintained.

EFFECTS ON SAFETY:

-As discussed abuve, with the RCS in a reduced inventory condition, DHR flow rate 1may be limited to less than 2800 gpm. The desired source-of  :

vater (e.g.,; Borated Vater Storage Tank or a Clean Vaste Receiver Tank) to' raise RCS level may be at or belov the RCS boron-concentration. If-the boron concentration ~of the desired-source ~is lover than the RCS boron concentration, the current TS_3.1.1.2 vording prevents the use of that source in this situation,'and requires the use of a source of water of a higher: boron concentration (such as the Boric Acid Addition Tank (BAAT)).- This source-is used(until RCS level in raised high-

-enough to support increasing DHR flow rate above 2800 gpm, at which point.the lover boron concentration source may be used. The need to

-perform this change of: vater addition sources places an extra and unnecessary.burdenaon the operators during the evolution of changing ,

RCS inventory at lov RCS levels. The proposed TS change vould eliminate the need to perform'this source change, reduce the. complexity of.the evolution, remove an unnecessary burden _on the operators, and-1therefore have a positive impact on plant safety.

.As stated in TS Bases 3/4'1.1.2, a flow rate of.at least 2800 gpm vill circulatefan equivalent RCS volume of 12,110_ cubic feet'in approximately 30 minutes. It should.be noted that in Mode 6, there vouldibe no need to reduce DHR; flow rate below-2800 gpm, except in a

-reduced RCS inventory condition. At reduced inventory,'the decreased _

RCS liquid 1 volume significantly compensates for the decreased DHR flow rate,1such that there is less of an impact on the time required to circulate an equivalent RCS volume. Vieved strictly from the standpoint ofivolume turnover rate, this lessens the possibility'of incomplete mixing.

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. Docket Number 50-346~

, ' License: Number NPF 3 Serial Number 2007 Attachment-

'Page 3 Updated Safety Analysis Report (USAR) Section 15.2.4, " Makeup and Purification System Malfunction", describes the results of the analysir of-a boron dilution event due to a Makeup and Purification System malfunction. During refueling or maintenance operations when the reactor closure head has been removed, the sources of dilution water to the_ makeup tank and therefore to the RCS are closed, and the makeup pumps are not operatlic. Nonetheless, the consequences of accidentally filling the makeup tank with dilution water and starting the makeup pumps-has'been evaluated. Updated Safety Analysis Report Section 15.2.4.2.3 states: "The entire water volume from the makeup tank could be pumped into the Reactor Coolant System (assuming that only the coolant in the reactor vessel is diltited); the-reactor vould still be sevet'al-percent suberitical." The boron dilution event eaalyzed is independent of RCS_ flow rate, and therefore the proposed TS changes have no impact on the analysis.

The proposed change to TS 3.1.1.2 would allow the addition of water of lower boron concentration than exists in the RCS, in Mode 6 vith-the flow rate of-reactor coolant through the RCS less than 2800 gpm, provided that the boron concentration of the water to be added is equal to or greater-than the more restrictive reactivity condition specified in TS 3.9.1. This1 exception is acceptable since tha RCS boron concentration is assured to remain greater than the required refueling concentration. Therefore, in this situation, even if incomplete mixing did occur, it vould be of no adverse consequence to safety.

The proposed change to TS Bases-3/4.1.1.2 adds a discussion of the y proposed Mode:6 exception-to TS 3.1.1.2. This proposed Bases change l has.no_ adverse eftect on plant safety, t

SIGNIFICANT,HAZAPDS CONSIDERATION:

The Nuclear- Regulatory Commissiot. has:provided standards in 10 CFR 50.92(c) for determining whether'a significant hazard exists due to a proposed, amendment to an: Operating License for_a facility., A proposed amendment involves no significant hazards if operation of the facility in accordance vith the' proposed changes vould '(1) Not involve a significant-increase-in the probability or consequences of an accident previously evaluated;.(2) Not create the possibility of a new or is ~different kind of accident ftom any accident previously evaluated; or l' (3) -Not; involve a significant reduction in a margin of safety. Toledo l Edison has reviewed the_ proposed change and determined that a i

significant hazards consideration does not exist oecause operation of the' Davis-Besse Nuclear Power Station, Unit Number 1, in accordance with these changes vould:

L la. NotLinvolve a significant increase in the probability of an accident previously evaluated because no accident conditions or assumptions are significantly affected by the proposed changes.

-The proposed change to-Technical-Specification (TS) 3.1.1.2 adds an exception, applicable only in Mode 6, that allows water of a-y lower boron concentration than the Reactor Coolant System (RCS)to be added to the RCS with the flow rate of reactor coolant through

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I Docket Number 50-346

~1conse Number lNPF-3 Serial-Number 2007  ;

Attachment

'Page'4 the RCS less than 2800 gpm,-provided-that the water to be added meets the requirements of TS 3.9.1. TS 3.9.1 requires that in Mode 6, the boron concentration of all filled portions of the RCS and the refueling canal shall be maintained uniform and suffic'.ent to ensure that the more restrictive of two reactivity condl uons is met. If the RCS meats these reactivity condition requirements, and water.is added to the RCS that also meets the reactivity condition requirements of TS 3,9.1, then the RCS is assured to remain in compliance with the teactivity condition requirements.

The possibility that the added vater may be of lover boron concentration than-the RCS is, therefore, of no adverse consequence to safety. There is no effect on the initial conditions assumed for the boron dilution incident in the accident analysis.

The proposed change to TS Bases 3/4.1.1.2 is considered to be i administrative in nature.

Ib. Not involve a significant increase in the consequences of an accident previously evaluated because no accident conditions or assumptions are affected by the proposed changes. As discussed in item la. above, the-proposed additior. of the exception to TS 3.1.1.2 vill not cause a condition that would result in the RCS 3 not meeting the requirements of TS 3.9.1. The proposed changes do not alter the source term, containment isolation, or allovable releases. The proposed changes, therefore, vill not increase the radiological consequences of a previously evaluated accident.

l The proposed change to TS Bases 3/4.1.1.2 is considered to be I

administrative in nature,

, 2a. Not create the possi_bility of a new kind af accident _from any accident previously evaluated because no new accident initiators or assumptions are introduced by the proposed changes. The proposed change does not alter any accident sc_enarios. As discussed in item la. above, the proposed addition of the exception to TS 3.1.1.2 vill not cause a, condition that vould result in the RCS not meeting the requirements of TS 3.9.1. The proposed change to TS Bases 3/4.1.1.2 is considered to be administrative in nature. None of the proposed changes creates

.the possibility'of_a new kind of accident from any accident previously evaluated.

2b. Not create the possibility of a different kind of accident from any accident'previously evaluated because no different accident initiators or assumptions are introduced by he proposed changee l- The proposed changes do not alter any accident scenarios. As

[ discussed in item la. above, the proposed addition of the

exception to TS 3.1.1.2 vill not cause a condition that would result-in the RCS not meeting the requirements-of TS 3.9.1. The proposed change to TS Bases 3/4.1.1.2 is considered to be

-administrative'in nature. None of the proposed changes creates the possibility of a-different kind of accident from any accident previously evaluated.

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. . Docket-Number'50-346 '

. License Number NPP-3=

' Serial Number 2007 Attachment '

. 'Page 5' _

3. Not involve a significant reductioncin the margin of safety because:the proposed-change to TS 3.1.1.2,-as described above, vill not cause a condition that would-result in the RCS not meeting the requirements of TS 3.9.1. The margin of safety vill be. maintained by adhering to the limits specified.in that TS. The proposed change to TS Bases 3/4.1.1.2 is considered to be

-administrative in nature.

I CONCLUSION:

On the basis of the above, Toledo Edison has determined that the i License Amendment Request does not involve a significant hazards consideration. ;As this License Amendment Request concerns a proposed change to the. Technical Specifications that must be reviewed by the Nuclear Regulatory Commission, this License Amendment Request does not i constitute an unreviewed safety question.

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. ATTACHMENT:

Attached-are the proposed marked-up changes to the Operating License. ,

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