ML20056A775

Forwards Request for Addl Info Based on Review of Probability Safety Assessment at Plant

ML20056A775
Person / Time
Site:	South Texas
Issue date:	08/07/1990
From:	Dick G Office of Nuclear Reactor Regulation
To:	Hall D HOUSTON LIGHTING & POWER CO.
References
TAC-73009, TAC-73010, NUDOCS 9008090180
Download: ML20056A775 (4)

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., August 7, 1990 Doc'ket Nos. S0-498 ,

and 50-499-Mr.. Donald P. Hall 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) i During the review of th'e PSA, we have determined the need for additional infor - ,

mation.- Enclosed is a if.st of' questions-from the NRC technical staff and our contractor concerning primarily the area of huinan reliability analysis. If l clarification of the questions is required by yotr staff, please have-them I

contact me. "

Following ieceipt of the answers, we expect to be able to co:nplete our. review of the internal events portion of the PSA.

Sincerely, OriginalSignedthi George F. Dick, Jr. , Project Manager Project Directorate IV-2

, Division of Reactor Projects - III,.

L IV, V and Special Projects l Office of Nuclear Reactor Regulation l-l-

Enclosure:

South Texas PSA Quertions DISTRIBUTION Doegetfliesy OGC cc w/ enclosure: NRC PDR E. Jordan l- See next page Local POR ACRS (10)

D. Crutchfield J. Wiebe B. Boger E. Chelliah PDIV-2 R/F H. Vandermolen PDIV-2 Plant File M. Cunningham .;

E. Peyton A. El-Bassioni '

9008090180 900807 G. Dick G. Kelly

=PDR .ADOCK 03000498 P- PDC OFC  : PDIV-2/LA  : PDIV-2/PM.  : PDIV-2/  :  :  :

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NAME $E GDick:ye N $CGrime $ $

-DATE : 8/7 /90  : 8/07/90  :  :  :  :

8]/90 OFFICIAL RECORD COPY b Document Name: ' SOUTH TEXAS PSA QUESTIONS

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Mr.-Donald P.; Hall ' h. ';.-

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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 y

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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 76704 Bethe sda , ' Ma ryl and 20814 Mr. R. J. Costello Bureau of Radiation Control >

Mr. M. T. Hardt State of Texas City Publ.ic Service Board 1101 West 49th Street P 0. Box 1771 Austin, Texas- 78756 i San Anton,io, 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 i P. O. Box'2121 Houston, Texas 77208 Lorpus Christi, Texas 78403 ,

INP0 Records Center I 1100-Circle 75 Parkway

~ Atlanta, Georgia 30339-3064 Regional Administrator, Region IV  !]

U.S. Nuclear Regulatory Commission  !

611 Ryan Plaza Drive, Suite.1000 Arlir -ton, Texas 76011 Mr. Joseph M. Hendrie 50 Be11 port Lane Be11 port, New York 11713 p Judge, Matagorda County Mat.agorda County Courthouse '

1700 Seventh Street Bay City Texas 77414 Mr. M. A. McBurnett Manager, Operation: Support Licensing L Houston Lighting & Power Company L 'P. O. Box 289-Wadsworth, Texas 77483

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South Texas Project, Units 1 and 2 Docket Nos. 50-498 and 50-499 Request for' Additional Information South Texas PSA Questions i

' General

1. Since the STP.PRA used a unique Human Reliability Analysis (HRA) Methodo-logy..which is a variation of three other methodologies (SLIM, SHARP, and s THERP), more documentation (in summary form) should be provided. This

' documentation should include: a summary of the deviations from the 'three "

original methodologies, justification for these deviations, and references for the three documents. i t

Sections 15.1 and 15.2 I

1. SLIM is broice int 6 ateps. The variation of SLIM used by the STP included t a step one that was an adaptation of s' as one and two of SHARP. Provide- C more information on what was used from the two steps of SHARP and why this ]

was considered desirable.

2. Provide a definition of a split fraction failure criteria.

3. The scenario sheet form is used to implement step four of the adapted SLIM methodology. It is implied in the documentation that this form is an adaptation of step three from SHARP. However, SHARP documents operating experience and influence parameter as a major portion of the.

step. Step four of the adapted methodology doesn't include either.

Provide an explanation-for this.

4. Provide additional information on the thermal hydraulic analysis _that was used to determine the approximate time windows.

5. A descriptive scaling guide was developed for each of the Performance Shaping Factors (PSFs). Provide infurmation on the history of this e development, i.e., how the guides we"e developed, who was involved, and how the guides were utilized in the analysis.

Section 15L3

1. With respect to certain critical human error probability (HEP) data

'_ (such as miscalibration of level sensors) documented in Appendix D of the South Texas PRA, reference has been made to those HEPs developed in the Seabrook PRA. Provide discussions related to the applicability of the HEPs of the Seabrook PRA (based on the above example).

L Section 15.4 L 1. The PSFs were evaluated using H, M, and L ratings. Provide a discussion on the criteria used to determine which rating was appropriate for a PSF. Also, include information on how the rating system was developed and its advantages.

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2 Section~15.6

-1. Provide-discussions related to the development of a time-dependent cumulative probability distribution function used to characterize the-recovery of the South Texas grid ~and the repair and/or restoration of the onsite diesel generators.

2 Provide discussions regarding the probability distributions associated with the tables on recovery actions, pages 15.6-7, 15.6-8, 15.6-9 and

[T 15.6-16.

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