ML051260283

STP Characterization Process

ML051260283
Person / Time
Site:	South Texas
Issue date:	05/21/2004
From:	Michael Webb NRC/NRR/DLPM/LPD4
To:	Schinzel G Office of Nuclear Reactor Regulation
Webb M, NRR/DLPM, 415-1347
Shared Package
ML051600374	List: ML051260197 ML051260208 ML051260274 ML051260279 ML051260281 ML051260282 ML051260283 ML051600345
References
Download: ML051260283 (4)

Text

Michael Webb - STP Characterization Process Page 14 From: Michael Webb To: Schinzel, Glen Date: 5/21/04 3:10PM

Subject:

STP Characterization Process Glen, I have attached comments that were forwarded to me by the staff of the Safety Programs Section of the Probabilistic Safety Assessment Branch regarding the South Texas Project characterization process as discussed in STP letters dated October 7, 2003, and March 4 and 16, 2004.

After you and your colleagues have had a chance to evaluate them, we can set up a call to discuss them further. We will target late morning on Tuesday, June 1st, as a possible time for the call.

Thanks, Mike Webb NRC Project Manager for South Texas Project 301-415-1347 CC: crgrantom@stpegs.com; Head, Scott DI ,

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.TP Mail Envelope Properties (40AE5431.2A6: 5: 21368)

Subject:

STP Characterization Process Creation Date: 5/21/04 3:10PM From: Michael Webb --

Created By: MKW@nrc.gov Recipients Action Date & Time nrc.gov owf2_po.OWFN_DO Delivered 05/21/04 03:1OPM SCD1 BC (Stephen Dinsmore) Opened 05/21/04 03:10PM nrc.gov owf4.po.OWFNDO Delivered 05/21/04 03:1OPM MKW BC (Michael Webb) Opened 05/21/04 03:1 IPM stpegs.com Transferred 05/21/04 03:10PM crgrantom CC (crgrantom@stpegs.com) geschinzel (Schinzel, Glen) smhead CC (Head, Scott)

Post Office Delivered Route owf2_po.OWFNDO 05/21/04 03:1OPM nrc.gov owf4_po.OWFNDO 05/21/04 03:10PM nrc.gov stpegs.com Files Size Date & Time STPCategorization .wpd 10229 05/21/04 02:56PM MESSAGE 1377 05/21/04 03: 1OPM Options Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard Reply Requested: No Return Notification: None Concealed

Subject:

No Security: Standard To Be Delivered: Immediate Status Tracking: Delivered & Opened

Change to South Texas Project's Categorization process Change 1, Letter October 7, 2003, Clarification of the up-date interval The procedural change clarifies the difference between updating the PRA, re-calculating the SSC risk-rankings with the PRA, and finalizing the risk-rankings in the Working group. All the PRA manipulations, including recalculations of the SSCs risk-rankings are done o the 36 month schedule. The working group must review and approve the SSC rankings and incorporate any changed rankings into the implementation documentation and processes. This is to be done in a "timely manner" after recalculating the SSCs risk ratikingsr/'

Evaluation: d;a the The original documentation could be interpreted to req thatthe n eded to complete the review, approve, and incorporation of the new SSC rankihgs intoAI implerintationjprocesses by the end of the 36 month interval. STP correctly notes that this would requirea 'less than 36 month update schedule for the PRA because it takes some months for the WG to cothplete its work.

The 36 month interval is not a derived value but a selected value intended to assure that periodic updates are performed. Allowing some extra time to incorporate and change into the processes does not defeat the intent of periodicfpdateX;

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Conclusion:==

5, t::'-e This clarification is reasonable. A/ -8 Change 2?L6tter MarcI,4:,2004, Change inhwthe out-of-service for maintenance sensitivity study isl6onducted.

Initially, all the SSCs thate'might be out for maintenance were set in an unavailable state and the risk-rankingrall -otheSSSCs evaluat6d. This illustrates the safety significance of the population of SSCs during the maintenance activities. The licensee will now increases the unavailability of the SSGs that might be out for maintenance by a factor of ten instead of setting them to unavailable.

Evaluation:

s noted in the icen e's letter the SE states that "equipment planned to be out of service.. Is et to unavailable." The licensee process no longer complies with this statement. Further discussion'withithe license is warranted to clarify what the sensitivity study was intended to investigate and how the old and new method supports this investigation.

Change 3: Letter dated March 16,2004, Change in the use of quantitative sensitivity study results in the categorization process.

After approval of the GQA program, all SSCs were placed in the highest safety-significance category indicated by the base line results and all of the sensitivity studies. The expert panel was not authorized to reduce the ranking. STP now ranks the SCC according to its baseline ranking and provides the results of the sensitivity study for consideration by the expert panel in case they want to increase the significance.

Evaluation; Both the GQA RG and the staff's SE allow for the plai significance of the base-line result, and providing the sensitivity studies for their consideration.

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Conclusion:==

The change results in a process that fully comports w of the more conservative process that was used earlier.