ST-HL-AE-2940, Application for Amends to Licenses NPF-76 & NPF-80, Reflecting Reperformed Dose Analyses Incorporating Effects of HVAC Heater Failures Identified in Revised Failure Modes Analysis Calculations

Application for Amends to Licenses NPF-76 & NPF-80, Reflecting Reperformed Dose Analyses Incorporating Effects of HVAC Heater Failures Identified in Revised Failure Modes Analysis Calculations

ML20246K898
Person / Time
Site:	South Texas
Issue date:	07/14/1989
From:	Rosen S HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20246K903	List: ML20246L039 ST-HL-AE-2940, Application for Amends to Licenses NPF-76 & NPF-80, Reflecting Reperformed Dose Analyses Incorporating Effects of HVAC Heater Failures Identified in Revised Failure Modes Analysis Calculations
References
ST-HL-AE-2940, NUDOCS 8907180294
Download: ML20246K898 (9)

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co mp a nyS uth Texas Project Electric GeneratingP.Station O. Box 289 Wadsworth, Texas 77483 Houston Lighting & Power July 14, 1989 ST-HL-AE-2940 File No.: G09.17, G09.18, C20, G21, M08.05, M08.06, N02.06 10CFR100 11 10CFR50.59 10CFR170.12 10CFR51.22 10CFR50.90 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 South Texas Project Electric Generating Station Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Application for License Amendment for FSAR Change for LOCA And Fuel Handling Accident Dose Analyses Reference (1) Letter ST-HL-AE-2942 from M.A. McBurnett to USNRC Document Control Desk, dated January 30, 1989 Recently, evaluations of LOCA doses, (offsite, Control Room and TSC) and fuel handling accident doses were submitted to the NRC that addressed the effect of unconsidered filter heater failures in the Fuel Handling Building (FHB) and Control Room HVAC Systems. Subsequently, dose analyses have been reperformed to incorporate the effects of HVAC heater failures identified in revised FMEA calculations. The dose analyses affected by the HVAC heater failures include the LOCA offsite doses, the LOCA Control Room and TSC doses, and the fuel handling accident offsite doses (accident in Fuel Handling Building only).

In addition, we have processed a pending FSAR change which incorporates LOCA and Gaseous Waste Processing fystem (GWPS) failure dose reanalysis results. The LOCA reanalysis was performed to account for a Control Room HVAC recirculation system configurat-ion which could allow the introduction of 235 cfm of makeup air to the Control Room which does not pass through the Control Room recirculation filter units and revised iodine plate-out values due to a reduction in the surface area available for plate-out. The GWPS failure reanalysis included final atmospheric dispersion factors for a GWPS failure. The analyses reflect the original plant design; i.e., no modification is involved.

8907180294 890714 PDR ADOCK 05000498 p PNU S3/LIC001/ew A Subsidiary of Houston Industries incorporated CDl E-_ -_ - _ - - _ _ _ _ _ _ _ _ _ _ _ - - _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ]h

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Houston Lighting & Power Company ST-HL-AE-2940 File No.: G09.17, G09.18,

. S6uth Texas Project Electric Generating Station G20, C21, M08.05 M08.06, N02.06 Page 2 Although the doses increased, they remained below the limits established in GDC 19, SRP 6.4, SRP 15.7.4 and 10CFR100. HL&P does not believe the dose analysis change affects the staff's conclusions in the STP.SER. However, it meets the criterion of 10CFR50.59 for being a

" change" where the consequences of an accident have increased and is therefore considered an unreviewed safety question. In this case,

" change" is considered to be a case where data is available which was not reviewed by the staff in developing its SER.

The changes provided in this letter include the revised FMEAs and the revised dose analyses. The annotated FSAR pages, description of the changes, and safety evaluation s.re attached. HL&P will incorporate the I changes into the STP Updated FSAR subsequent to their approval by NRC staff.

The doses presented in this change supersede thore previously transmitted by Reference 1, " Voluntary LER 88-066". There are slight changes which resulted from the dose reanalysis committed to as one of the corrective actions given in LER 88-066.

HL&P has reviewed the proposed change in accordance with the requirements of 10CFR50.59 and 10CFR50.92. The results indicate that an unreviewed safety question (USQ) is involved. HL&P has reviewed the USQ and concluded there is no resulting significant hazard.

Based on the information contained in this submittal and the NRC Final Environmental Assessment for South Texas Units 1 & 2, HL&P has concluded that pursuant to 10CFR51.22 there are no significant radiological or non-radiological impacts associaced with the proposed change and that the proposed license amendment will not have a significant effect or the quality of the human environment. 1 The South Texas Project Nuclear Safety Review Board has reviewed and approved the attached proposed revision and concurs with the 10CFR50.59 1 determination.

In accordance with 10CFR50.90, HL&P therefore requests that licenses NPF 76 and NPF 80 for STP Units 1 and 2 be amended to allow incorporation of the dose reanaP sis.

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 & Power Company ST-HL-AE-2940 .

• File No.: G09.17, G09.18, S6uth Texas Project Electric Generating Station ,

C20, G21, M08.05 M08.06, N02.06 Page 3 l

If you should have any questions on this matter, please contact Mr.

A. W. Harrison at (512) 972-7298.

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S. L. Rosen Vice President Nuclear Engineering and Construction AWH/dv

Attachment:

1) Description of Change

2) Safety Evaluation

3) Proposed FSAR Revisions S3/LIC001/ew

t' i ST-HL AE-2940 File No.: G09.17, G09.18, Houston Lighting & Power Company S6uth Texas Project Electric Generating Station G20, G21, M08.05, M08.06, N02.06 Page 4 cc:

Regional Administrator, Region IV Rufus S. Scott Nuclear Regulatory Commission' Associate General Counsel 611 Ryan Plaza Drive, Suite 1000 Houston Lighting & Power Company Arlington, TX 76011 P. O. Box 1700 Houston, TX 77001 George Dick, Project Manager U.S. Nuclear Regulatory Commission INPO Washington, DC 20555 Records Cettter 1100 circle 75 Parkway Jack E. Bess Atlanta, GA 30339-3064 Senior Resident Inspector / Unit 1 c/o U.S. Nuclear Regulatory Dr. Joseph M. Hendrie Commission 50 Bellport Lane P. O. Box 910 Bellport, NY 11713 Bay City, TX 77414 D. R. Lacker J. I. Tapia Bureau of Radiation Control Senior Resident Inspector / Unit 2 Texas Department of Health c/o U.S. Nuclear Regulatory 110 W. 89th St.

Commission Austin, Tx. 78756-3189 P. O. Box 910 Bay City, TX 77414 J. R. Newman, Esquire Newman & Holtzinger, P.C.

1615 L Street, N.W.

Washington, DC 20036 R. L. Range /R. P. Verret Central Power & Light Company P. O. Box 2121 Corpus Christi, TX 78403 R. John Miner (2 copies)

Chief Operating Officer City of Austin Electric Utility 721 Barton Springs Road Austin, TX 78704 R. J. Costello/M. T. Hardt City Public Service Board P. O. Box 1771 I

San Antonio, TX 78296 J

Revised 12/21/88 S3/LIC001/ew i

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ST-HL-AE-2940 I File No.: C09.17, etc. .{

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UNITED STATES OF AMERICA  ;

1 NUCLEAR REGULATORY COMMISSION 1

In the Matter )

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Houston Lighting & Power ) Docket Nos. STN 50-498 Company,.et al , ) STN 50-499

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South Texas Project )

Units 1 and 2 )

1 AFFIDAVIT S. L. Rosen being duly sworn, hereby deposes and says that he is Vice President, Nuclear Engineering and Construction of Houston Lighting & Power Company; that he is duly authorized to sign and file with the Nuclear Regulatory Commission the attached proposed revision to the Final Safety Analysis Report for changes to llVAC FMEA's and LOCA doses (Offsite, Control Room and TSC), GWPS failure doses and fuel handling accident doses; is familiar with the content thereof; and that the matters set- forth therein are true and correct to the best of his knowledge and belief.

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A S. L. Rosen Vice President, Nuclear Engineering and Construction STATE OF TEXAS )

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l Subscribed and sworn po before me, a Notary Public in and for the State of Texas this l9 ih day of J otI , 1989.

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arf e Notary Publicoin and for the State of Texas S3/LIC001/ew

'i a Attachment 1 ST-HL-AE-2940 Page 1 of 3 i DESCRIPTION OF CHANGE 1

l HL&P has reperformed Control Room, Technical Support Center (TSC) and offsite dose analyses to include effects due to hestar failure in the Control-Faom or FHB HVAC systems which were not previously considered and finalized design calculations which have not yet been incorporated in the FSAR.

Contributions to the revised dose analyses are from the following sources:

1. Reduced surface area for iodine plate-out subsequent to LOCA resulted from a recalculation of the reactor containment heat sink inventory. Reduced plate-out increases iodine concentration in the containment atmosphere and consequently increases Control Room, TSC and offsite doses from postulated containment leakage.

2. A flow imbalance condition can be postulated to occur in the Fuel Handling Building HVAC exhaust system (without a single failure) such that flow through one train of filters is insufficient for operation of the heaters, reducing filtration efficiency in that train. This condition is alarmed to the operators, and credit for operator action is taken at 30 minutes to restore exhaust flow through filter units with heaters in operation. This condition affects Control Room LOCA doses, LOCA offsite doses and FHB fuel handling accident offsite doses.

3. A Control Room recirculation condition can exist in which 235 cfm of makeup air to the Control Room is filtered only by the Control Room maker- filter units,- bypassing the Control Room cleanup filter unit This situation arises when one of the three trains of Control Room filtration does not start after'the accident. Under those circumstances, as much as 235 cfm of makeup air can infiltrate the Control Room through the idle train, increasing Control Room doses.

4. Postulating a heater failure in one train of Control Room makeup filters reduces the efficiency of the carbon filter units and consequently increases dose in the Control Room. This condition has been analyzed and determined to be not limiting in the Control Room dose analysis.

5. Postulating a heater failure in one bank of FHB HVAC exhaust filters similarly reduces filtration efficiency. This heater failure increases FHB fuel handling accident doses, but was analyzed and determined to be not limiting for the Control Room LOCA doses and LOCA offsite doses.

6. Higher fan shaf t inleakage to the TSC was determined during testing and is used in the TSC dose analyses. The shaft inleakage flow is introduced directly to the TSC, bypassing the filters. This item I

affects the TSC doses only.

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Attccha nt 1 ST-HL-AE-?C40 Page 2 of 3

7. The X/Q vclues for the GWPS failure analysis were finalized using value,s which were rounded from three significant figures to two.

This contributes only to the offsite dose. (X/Q values for the Control Room dose were determined in a separate, unaffected, calculation.)

Item 1 affects all LOCA doses, i.e. , offsite, Control Room and TSC, and is not the result of a single failure. Item 2, as identified above, is also not the result of a single failure, and affects the LOCA doses from ESF leakage to Control Room and offsite, as well as the FHB fuel handlin5 accident cases. Item 7 affects the offsite GWPS failure accident doses only. Items 3, 4 and 5 affect doses when considering single failures; these items are analyzed one at a time to determine the limiting doses. The limiting failure for the LOCA offsite doses and Control Room doses was determined to be the failure of a single standby diesel generator.

During reperformance of the Control Room dose calculations, it was determined that the reduced occupancy factors were not considered for the ESF leakage contribution dose. The revised doses reflect occupancy factors of 100%

for 0-24 hours, 60% for 1-4 days and 40% for 4-30 days, as prescribed in SRP-6.4.

The limiting doses are shown in the proposed FSAR revisions (Attachment 3) and are also shown below:

Control Room Doses Thyroid (reml Whole Body Skin Gamma (rem) Beta (rem)

Containment leakage contribution 17.62 1.5 -5 18.7 ,4 ESP leakage contribution 1.415 5.97 x 10 5 . 6 x 194 Containment purge contribution 0.048 5.4 x 10 8.2 x 10 Direct dose from Containment ---

0.11 --- l Direct dose from cloud of released fission products --- 0.83 ~~~

Iodine filter loading --- 2.21 x 10 -3 ---

Total 19.08 2.44 18.70 TSC Dose

• 28.40 4.80 21.67 LOCA Dose 2

0-2 hour Exclusion Zone Boundary 1.58 x 10 2.29 1.19 0-30 day Low Population Zone 6.24 x 10 0.69 0.43 GWPS Failure Dose Exclusion Zone Boundary 8.5 1.9 ,7 2.5 ,1 Low Population Zone 2.5 5.6 x 10 7.4 x 10 FHB Fuel Handling Accident Dose i Exclusion Zone Boundary 2.84 x 10 2.73x10j 3.58 x 10'I )

Low Population Zone 8.30 8.0 x 10 1.05 x 10 1

• LOCA is limiting accident S3/LIC001/ew

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Attachment'1' ST-HL-ri-2940

'Page 3 of 3

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These doses are within the limits established by regulatory guidance in 10CFR50 Appendix A GDC 19, 10CFR100, SRP 6.4 and SRP 15.7.4 as identified below:-

. Thyroid Whole Body Comma Skin Beta Control Room Dose 30 rea 5 rea 30 rem TSC Dose 30 rem 5 rea 30 rem IDCA Offsite Dose 300.rea 25 rem ---

GWPS Failure Dose 75'res. 6 rem ---

Fuel Handling Accident Dose 75 rea 6 rem - - -

The analyses for equipment environmental qualification have been reviewed,

'and were determined to be not impacted. The total release to containment is not affected; the iodine plateout removal term has been reduced due to lower calculated surface area available for plateout. Since more activity.is

'available for containment leakage. the activity remaining is lower and previously calculated radiation exposure is conservative.

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' Attachment 2 ST-HL-AE-2940 Page 1 of 1 SAFETY EVALUATION FOR SIGNIFICANT HAZARDS CONSIDERATIONS

1) Effect on Probability and Consequences of an Accident:

The proposed change concerns only recalculation of consequences of presently-postulated accidents. No system o?: plant changes are involved. Therefore, there-is no effect on the probability of an accident.

The proposed change documents revised analyses which determined increased Control Room, TSC and offsite doses of postulated accidents. The Control Room and TSC doses remain below the reguintory limits established in CDC 19 and SRP 6.4. Offsite doses for the'affected accidents are minimally affected. Occupational doses per 10CFR51.22 are unaffected. There is no impact on equipment qualification. A detailed evaluation is provided in Attachment 1.

2) Effect on Possibility of a New or Different Kind of Accident:

No plant modifications are involved. There is consequently no effect on the possibility of a new or different accident-. The changes to the HVAC FMEAs are addressed by this revised dose analysis.

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3) Effect on Margin of Safsty as Defined in Technical Specifications:

Although the consequences of the accident have increased slightly, the affected systems (Control Room HVAC and FHB HVAC system, Containment Spray and CWPS) still function within the bounds prescribed by the Technical Specifications. The revised analyses determine the doses considering all i

appropriate parameters and single failures. There is no change in the basis of the STPEGS Technical Specifications. Therefore, the Technical Specification margins are maintained.

EVALUATIONS AND CONCLUSIONS y The analyses performed represent the as-designed and as-built configuration of the plant; the increased doses do not result from proposed modifications. The newly calculated doses remain below limits established in regulatory guidance in GDC 19, SRP 6.4, SRP 15.7.4, and 10CFR100.11. There is no impact on environmental qualification of equipment.

Based on the small magnitude of the change, HL&P has concluded that there is no significant hazard associated with the recalculated doses.

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