TXX-9803, Application for Amends to Licenses NPF-87 & NPF-89, Increasing RWST low-low Level Setpoint

Application for Amends to Licenses NPF-87 & NPF-89, Increasing RWST low-low Level Setpoint

ML20203K852
Person / Time
Site:	Comanche Peak
Issue date:	02/27/1998
From:	Terry C, Walker R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20203K855	List: ML20203K862 TXX-9803, Application for Amends to Licenses NPF-87 & NPF-89, Increasing RWST low-low Level Setpoint
References
TXX-98033, NUDOCS 9803050253
Download: ML20203K852 (10)

Text

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M EE .= Log # 1XX 98033 3 File # 916 (3/4.3) 10010 7t/ ELECTRIC Ref. # 10CFR50.90 10CFR50.36 c, % % February 27, 1998 sense w e m us.c

& PrincipelNwlear ORlcer i

U. S. Nucitar Regulatory Commission Attn: Document Contro' Desk

! Washington. DC 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET NOS. 50 445 AND 50 446 l

SUBMITTAL OF LICENSE AMENDHENT REQUEST 98 001 REVISION TO RWST LOW LOW LEVEL SETPOINT REF: 1) TV Electric Letter, logged TXX 97173, "LER 445/97 002 01,"

from C. L. Terry to NRR dated August 15, 1997.

2) TV Electric Letter. logged TXX 97105, from C. L. Terry to NRR dated May 15, 1997.

Gentlemen:

Pursuant to 10CFR50.90, TU Electric hereby requests an amendment to the CPSES Unit 1 Operating License (NPF 87) and CPSES Unit 2 Operating License (NPF l'9) by incorporating the attached changes into the CPSES Units 1 and 2 Technical Specifications. These changes apply equally to CPSES Unit I and Unit 2.

TV Electric proposes to increase the RWST Low Low level setpoint from "240%" io "a45%" of span for CPSES Units 1- and 2. While reviewing concerns regarding the Containment Spray Switchover to Recirculation reported in Reference 1, TU Electric concluded that the RWST Low Low level setpoint should be raised in order to increase the volume available to complete containment spray switchover without turning off the containment spray cumps. The impact of increasing the RWST Low Low level setpoint is conservative with respect to the current Technical Specifications, but necessitates submittal of a License Amendment Request to ensure the Technical Specifications reflect the new setpoint and allowables for RWST Low Low. Administrative controls are already in place to ensure the licensing basis for ECCS injection is maintained.

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TXX.98033 Page 2 of 2 Attachment 1 is the required affidavit. Attachment 2 provides a detailed I description of the proposed changes, a safety analysis of the proposed changes and-Til Electric's determination that the proposed changes do not l involve a significant hazard consideration. Attachment 3 provides the l af fected Technical Specification pages marked up to reflect the proposed

-changes. Attachment 4 provides a mark up of the Improved Technical S)ecification pages submitted in reference 1 to reflect the proposed c1anges from reference 2.

TV Electric requests approval of this proposed license amendment 18 months from the date of this letter, with implementation of the Technical Specification changes to occur within 30 days 6fter NRC approval.

In accordance with 10CFR50.91(b), TU Electric is providing the State of Texas with a copy of this proposed amendment.

Should you have any questions, please contact Mr. Jimmy Seawright at .

(254) 897 0140.

Sincerely, S. 8, 7bAAq' .

C. L. Terry By: ofG18-Roger 4. Walker Regulatory Affairs Manager JDS/grp Attachments: 1. Affidavit 2, Description and Assessment __

3. Affected Technical Specifications pages as revised by all a) proved license amendments

4. Affected ITS Tec1nical Specification Pages

5. Letter logged TXX 97173, dated August 15, 1997

6. Federal Register Vol. 51, No. 44. Rules and Regulations, March G. 1986, page 7751

7. TXX 97105, dated May 15, 1997 (clo) c- Mr. E. W. Herschoff, Region IV Hr. T. J. Polich, NRR Hr. J. I. Tapia. Region IV Resident Inspectors. CPSES Mr. Arthur C. Tate Bureau of Radiation Control Texas Department of Public Health 1100 West 49th Street Austin, Texas 78704

l Attachment 1 to TXX 98033 Page 1 of 1 UNITED STATES OF AMERICA l NUCLEAR REGULATORY COMMISSION l

l In the Matter of )

) .l Texas Utilities Electric Company ) Docket Nos. 50 445 i ) 50 446 l (Comanche Peak Steam Electric ) License Nos. NPF 87 Station, Units 1 & 2) ) NPF 89 AFFIDAVIT Roger D. Walker being duly sworn, hereby deposes and says that he is Regulatory Affairs Manapar of TV Electric, the licensee herein; that he is tiuly authorized to sigh and file with the Nuclear Regulatory Commission this License Amendment Request 98 001: that he is familiar with the content thereof; and that the matters set forth therein are true and correct to the best of his knowledge, information and belief, h4P4 A y R69VrQjfhalker Regulatory Affairs Manager STATE OF TEXAS )

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Sybscribed an't sworn to before me, on this j'[ek day of JA42a1 u . 1998.

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v ATTACHMENT 2 te TXX 98033 DESCRIPT13N AND ASSESSMENT s

• Attachment 2 to TXX 98033 Page 1 of 6 DESCRIPTION AND ASSESSMENT

1. BACKGROUND While reviewing Refueling Water Storage Tank (RWST) level setpoint calculations, to determine if the empty alarm setpoint could be lowered, an invalid assumption was identified. It was originally assumed that the containment spray pump switchover from the RWST to the sumps would take less than one minute. Contrary to this assumption, design information showed the stroke time for the sump valves and the tank isolation valves to be 120 seconds each. Therefore. considering operator response times, complete isolation of the RWST could take between 4 and 5 minutes.

TV Electric determined that the identified sequence of events is a more limiting condition than the current analysis assumed in the licensing basis and therefore concluded that the availible volumes in the RWST were outside of the CPSES design basi . This condition was reported pursuant to 10CFR50.'/2 [Ref. 1).

The valve stroke times were later found to be 20 and 120 seconds for the sump and tank isolation valves, respectively. It was determined that through modifications to the RWST isolation valve operator, the closing time for the minimum tank isolation achievable spray valve could be reduced to 90 seconds. The aump switchover time was concluded to be 170 seconds. Additionally, t1e design and licensing basis require a caution in the a)propriate emergency operating procedures to stop any ECCS pump still ta cing suction from the RWST on receipt of the empty alarm. The procedure also contains com>ensatory steps to stop ECCS pumps associated with a suction v:lve from tie sump if the suction valve fails to open, (single active failure) to protect the pumps against a loss of net positive suction head (NPSH). These additional actions can add to the time required to complete containment spray switchover.

An anglysis of containment spray pump switchover, sta:' ting at the RWST empty alarm and using the times determined above, was performed to address this condition. It was concluded that the switchover alone coulci be completed: however, there was insufficient volume in the RWST to complete switchover and to provide time for sto) ping any operating pumps per the caution statement. An analysis of t1e ECCS pump loss of NPSH protection caution at recei)t of empty alarm showed that there was sufficient volume to protect bot 1 ECCS and spray pumps; however. there was insufficient instrumentation accuracy for a separate caution for the spray pumps after receiving an empty alarm on the RWST. The option of j stopping the spray pumps and re 4arting them after the valves were re-aligned was evaluated. This option affects containment heat removal f (for loss of Coolard Accident and offsite radiological dose (LOCA) and Main calculations Steam Line Break (MSLB))

(for LOCA). In addition, stopping the spray pumps for switchover would increase the probability l

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.- Attach ent 2 to TXX 98033 Page 2 of 6 of their malfunction through a subsequent failure to start. The conclusion presented in this analysis was Stat spray pump switchover must begin prior to the empty alarm.

The existing switchover procedure initiated the containment spray switchover on level indication prior to receipt of the empty alaro:

however, under design basis accident conditions and assumptions. it could not be assured that both ECCS and containment spray switchover could be completed without stopping the spray pumps. Therefore, -

containment spray flow might be stopped for several minutes while the spray transfer was being completed with non operating pumps. An analysis was performed to demonstrate that the RW$T volume between the new Low Low alarm and the empty alarm was sufficient to allow for the RWST/ sump switchover. TU Electric revised the calculations and setpoints to demonstrate that switchover can be completed without stopping the containment spray pumps in the event of loss of coolant accident. Under design basis accident scenarios, the )revious existing condition was outside the current. licensing basis and led the >otential to increase the radiological consecuences as presented in the :SAR due to the temporary stopping of the spray pumps.

These changes to the plant Technical Specifications are specific to CPSES Units 1 and 2. and are needed to ensure that the RWST level is properly accounted for in the Technichi Specifications.

II. DESCRIPTION OF TECHNICAL SPECIFICATIONS CHANGE REQUEST TV Electr1c proposes changing Technical Specification Table 3.11, item from ">40%" to "245t" of span. The change requires the allowable values for each unit for this setpoint to be increased by the same St.

Additionally, the improved Technical Specifications submitted by

-Reference 3 are impacted: therefcre, revised ) ages to the improved Technical Specifications are also provided. T11s change is consistent with the Westinghouse Improved Standard Technical Specifications (NUREG.

1431, Revision 1).

III. ANALYSIS TV Electric revised the calculations and setpoints to demonstrate that raising the RWST Low Low setpoint is acceptable. The following analyses have been completed fo" coth Units J and 2 and are described below.

• EFFECT ON RWST VOLUMES Maximum RWST volumes previously calculated are unaffected.

Minimum RWST volumes for RWST ECCS injection prior to switchover

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.: Attach ent 2 to TXX 98033 Page 3 of 6 1

is reduced by 3) proximately 25,000 gallons due to r41 sing the Low-Low setpoint. T1e calculation of the minimum ECCS injection volume includes the level between the Tech Spec 3/4.5.1 minimum elevation and the low low setpoint plus full loop instrument uncertainty.

This conservatively minimizes the calculated volume assuming a (two out of four) control signal at the highest possible tank elevation.

EVALUATION OF ECCS INJECTION TIME REQUIREMENTS The revised RWST Low Low setpoint of 45% was evaluated to essure that the 10 minute ECCS injection time without operator action is maintained. By raising the RWST Low. Low setpoint 25 inches (5%),

approximately 25,000 gallons of available RWST volume is reallocated from )rior to reaching the Low Low setpoint to after reaching the Low .ow setpoint of 45%. Changing Low Low Setpoint from 40% to 45% yields a minimum ECCS injection volume, as described above, that continues to satisfy the CPSES licensing basis for the minimum time requirement for ECCS injection.

EVALUATION OF THE CONTAINMENT ECCS TRANSFER LEVEL ECCS switchover is conservatively assumed to occur at the RWST Low Low setpoint plus instrument uncertainty as described above.

• EFFECT "N CONTAINMENT FLOOD LEVELS Minimum Centainment flood levels are impacted by the RWST setpoint changes.

The above described reduction of injectics volume by raising the Low Low setpoint reduces the minimum containment level at the' time of RHR switchover to the sump by about 6 inches from 810' 3" to 809' 9". This is acceptable for RHR pump NPSH. NPSH analyses at a worst case pump runout flow of 4900 gpm show a margin of > 5 feet at an elevation of 808' 0" which is the containment floor elevation (i.e. a full sump).

Each RHR and spray pump suction pipe intake has a conical intake to prevent cavitation and is covered by a grating cage to protect against vortexing. Full scale model testing was performed in 1981.for the CPSES

sump design. The effectiveness of the grating cage was demonstrated during these tests. The minimum specified flood level for the testing was 810' 8". The minimum tested level and flow for a single suction line that confirmed the anti vortex design was approximately 810' 3" at up tu 8858 gpm. Since the maximum RdR runout flow is 4900 gpm, significantly less then the minimum tested flow of 8858 gpm. vortexing is not expected with a water level 21" above the full sump. Even if 4

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Attach:ent 2 to TXX 98033 Page 4 of 6 minor vortexing were to occur at RHR switchover, it would be quicky {

terminated by rising water level. In addition, the new minimum flood l 1evel is only an interim level since the spray pumps continue to inject RWST water during '.he entire ECCS switchover. The full scale model testing performed in 1981 confirmed the antivortexing design for both l the RHR and Containment spray pumps running. Since the b 21 at the l point in time that the containment spray pumps suction is shifted to the i sumps is greater than tested, and the total flow is less than tested.

l vortexing in the sump would not occur. Therefore, the reduction in minimum containment flood level for ECCS switchover does not significantly affect the RHR pump performance.

In summary, increasing the RWST Low Low setpoint from 40% to 45% restores the CPSES 11 cent,ing basis reported in LER 97 002 01 (reference 1) and continues to comply with the current Technical Specifications.

l IV. SIGNIFICANT HAZARDS CONSIDERATIONS ANALYSIS TU Electric has avaluated whether or not a significant hazaras consideration is involved with the proposed changes by focusing on the j three standards set forth in 10CFR50.92 as discussed below:

f 1. Do the proposed changes involve a significant increase in the probability or consequences of an accident previously evaluated?

The changes in the License Amendment Request proposes more restrictive setpoint Allowable Values for the RWST Low Low setpoint. This more restrictive value assures that all applicable safety analysis limits are being met. Changing an RWST Low Low setpoint from > 40t to a 45% in the Technical Specifications has no impact on the probability of occurrence of any accident previously evaluated. None of the accident analyses were affected, therefore, the consequences of all previously evaluated accidents remain unchanged, f Do the pro)osed changes create the possibility of a new-or different cind of accident from any accident previously evaluated?

The proposed changes involve the use of a more conservative value for the RWST Low Low setpoint. As such, none of the changes effect plant hardware or the operation of plant systems in a way that could initiate an accident. Therefore, the pro)osed changes do not create the possibility of a new or different cind of accident from any accident previously evaluated.

4 Attachment 2 to TXX 98033 Page 5 of 6

3) Do the proposed changes involve a cignificant reduction in a margin of safety?

There were no changes made to any of the accident analyses or safety analysis limits as a r9sult of this pro)osed change.

Further, the proposed change does not affect tie acceptance criteria for any analyzed event. ECCS, Containment spray, and the RWST will remain capable of performing their safety function, and the new requirement will continue to provide adequate assurtence of that capability. Haking the RWST Low Low setpoint 45% will function within the safety analysis limits assumed in the safety analyses as discussed in Chapter 15 of the FSAR. The margin of safety established by the Limiting Conditions for Operation also remains unchanged. Thus there is no effect on the margin of safety.

The Nuclear Regulatory Commission has provided guidance concerning the application of the standards for determining whether a significant hazards consideration exists by providing certain examples (51 FR 7751 Reference 2) of amendments that are considered not likely to involve significant hazards consider; tion. Example (ii) relates to a change that constitutes an additional limitation, restriction, or control not presently included in the technical specification, e.g. a more stringent surveillance requirement. This chang? requires a more stringent RWST setpoint.

{ Based on the above evaluations, TV Electric concludes that the activities associated with the above described changes present no significant hazards consideration under the standards set forth in 10CFR50.92 and accordingly, a finding by the NRC of no significant hazards consideration is justified.

V. ENVIRONMENTAL EVALUATION TV Electric has determined that the proposed amendment would change requirements with respect to the installation or use of a facility component located within the restricted area, as defined in 10CFR20, or would change an inspection or surveillance requirement. TV Electric has I evaluated the proposed changes and has determined that the changes do not involve (1) a significant hazards consideration (ii) a significant '

i change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposuce.

Accordingly, the proposed changes meet the eligibility criterion for categorical exclusion set forth in 10CFR51.22(c)(9). Therefore, pursuant to 10CFR51.22(b), an environmental assessment of the proposed changes is not required.

e Attachment 2 to TXX 98033 Page 6 of 6 VI. REFERENCES

1. TXX 97173 dated August 15, 1997.

2. Federal Register Vol. 51, N<.'. 44, Rules and Regulations.

March 6, 1986, page 7751 i

3. TXX 97105, dated Hay 15, 1997 (clo).

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