ML20058A594

Requests Addl Info Re Review of Probability Safety Assessment of Facility

ML20058A594
Person / Time
Site:	South Texas
Issue date:	10/18/1990
From:	Dick G Office of Nuclear Reactor Regulation
To:	Hall D HOUSTON LIGHTING & POWER CO.
References
TAC-73009, TAC-73010, NUDOCS 9010290030
Download: ML20058A594 (4)

Text

(7 October 18, 1990 Docket Nos. 50-498 and 50-499 Mr. Donald P. Hall L

Group Vice-President, Nuclear Houston Lighting & Power Company P. O. Box 1700 Houston, Texas 77251

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE REVIEW 0F THE PROBABILITY SAFETY ASSESSMENT (PSA), SOUTH TEXAS PROJECT, UNITS 1 AND 2 (TAC NOS. 73009 and 73010)

During the review of the PSA, we have determined the need for additional l

information.

Enclosed is a list of questions developed during the review of i

i the external events (other than fire) sections of the PSA.

If clarification of the request is required by your staff, please have them contact me.

f Sincerely,

)

OriginalSigned Bv:

George F. Dick, Jr., Project Manager i

Project Directorate IV-2

~

Division of Reactor Projects - III, IV, V and Special Projects j

Office of Nuclear Reactor Regulation

Enclosure:

'Docketfiled E. Jordan DISTRIBUTION South Texas PSA Questions ~

NRC PDR ACRS (10).

1 cc w/enclousre:

Local PDR OGC See next page D. Crutchfield H. Vandermolen M. Virgilio E. Chelliah PDIV-2 R/F G. Kelly PDIV-2 Plant File W. Beckner E. Peyton.

M. Wohl y

G. Dick A. Singh (R-IV)

M. Cunningham W. Jones (R-IV)'

l N. Chokshi-R. Kenneally j

j](l$C J. Linville j

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Document'Name:

SOUTH TEXAS PSA 73009/73010 g fo (

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9010290030 901018-

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PDR ADOCK 05000498

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G PNU j

Mr. Donald P. Hall.

cc:

Senior Resident Inspector Jack R. Newman, Esq.

U.S. Nuclear Regulatory Commission Newman & Holtzinger, P.C.

P. O. Box 910 1615 L Street, N.W.

Bay City, Texas 77414 Washington, D.C.

20036 Mr. J. C. Lanier Licensing Representative Director of Generation Houston Lighting and Power Company City of Austin Electric Utility Suite 610 721 Barton Springs Road Three Metro Center Austin, Texas 78704 Bethesda, Maryland 20814 Mr. R. J. Costello Bureau of Radiation Control Mr. M. T. Hardt State of Texas City Public Service Board 1101 West 49th Street P. O. Box 1771 Austin, Texas 78756 San Antonio, Texas 78296 Rufus S. Scott Mr. R. P. Verret Associate General Counsel Mr. D. E. Ward Houston Lighting & Power Company Central Power and Light Company P. O. Box 61867 P. O. Box 2121 Houston, Texas 77208 Corpus Christi, Texas 78403 INPO Records Center 1100 Circle 75 Parkway Atlanta, Georgia 30339-3064 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 i

Arlington, Texas 76011 Mr. Joseph M. Hendrie 50 Be11 port Lane Be11 port, New York 11713 l

Judge, Matagorda County Matagorda County Courthouse 1700 Seventh Street Bay City, Texas 77414 l

Mr. M. A. McBurnett l

Manager, Operations Support Licensing 1

l

~ Houston Lighting & Power Company-P. O. Box 289 l

Wadsworth, Texas 77483 l

l

j SOUTH TEXAS PROJECT, UNITS 1 AND-2 DOCKET NOS. 50-498 AND 50-499 PROBABILISTIC SAFETY ASSESSMENT REVIEW OF EXTERNAL EVENTS REQUEST FOR ADDITIONAL INFORMATION 1.

Discuss the basis for generic initiating event frequencies used in the spatial interaction analyses.

For example, for flood analysis, discuss what is a pipe section and how the failure frequencies of 8.0E-7 and 8.0E-6 are arrived at? Similarly, discuss basis for missiles generated by rotating machinery and pressurized canisters.

2.

Were any of the components which might impact seismic results found to be anchored by plug welds? If so, discuss the fragility calculations of these components with respect to capacity of plug welds.

3.

In the context of falling objects, Section 3.4.1.3.1, was the potential seismic interaction associated with the movable in-core flux mapping system considered? Portions of the in-core flux mapping system located above the seal table may not have been seismically analyzed.

Failure of this equipment during a seismic event could cause multiple failures at the seal table resulting in equivalent small-break LOCA.

4.

As discussed in the draft IPEEE generic letter (88-20, Supplement 4) and guidance document (NUREG-1407), for many external events (other than seismic and fire), if it can be ascertained that a plant has been designed-to meet current criteria (1975 Standard Review Plan), additional analysis may not be needed to evaluate severe accidents initiated by those external events.

In light of this, it would be very instructive to compare FSAR design criteria (flood level, wind speed, RGs used, etc.) with initiating event frequencies and corresponding criteria used in the PRA analysis in a~ tabular form.

(It is realized that such information is discussed in various sections throughout the PRA, however an organized comparison could be very useful).

It would also'be useful to know whether any changes have occurred at or near the site to alter the design information described in the FSAR, for example, construction of'a new facility or stacks, or changes related to transportation, chemical or other similar hazards.

5.

The flooding event associated with failure of the upstream dams, considers-two dams, the Mansfield and Buchanan dams.

The PRA analysis indicates l

that the water level at the site due to the failure of these two dams would be at El. 32.0 ft.

The following have not been addressed in this analysis.

Please explain:

I a.

Failure /effect of the Columbus Bend or other proposed / built dams.

l b.

Effect of upstream dam breaks on Main Cooling Reservoir (MCR) and Essential Cooling Pond (ECP).

.g.

P 6.

Several recovery actions are identified in Tables 15.5-12 through 15.5-17 with respect to seismic initiated sequences.

Discuss the basis for error rates associated with these actions under seismic environment.

Also, discuss impact of not including these recoveries on seismic induced core damage frequencies.

Recovery actions HECH03 and HECH04 are associated with starting Technical Support Diesel Generator (TSDG) and the Positive Displacement (PD) Pump; however, discussion in the seismic section implies guaranteed failure of TSDG with seismic induced loss of offsite power (LOOP), and Table 3.4.4-4 indicates very low capacity of the TSDG.

In light of this, clarify how these recovery actions are used in the analysis.

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