ML110680444

Comment (1) of Biff Bradley, on Behalf of Nuclear Energy Institute, Supporting Draft NUREG-1953 Re Confirmatory Thermal-Hydraulic Analysis Risk Models - Surry and Peach Bottom

ML110680444
Person / Time
Site:	Peach Bottom, Surry, Nuclear Energy Institute
Issue date:	02/23/2011
From:	Bradley B Nuclear Energy Institute
To:	Cindy Bladey Rulemaking, Directives, and Editing Branch
References
75FR80544 00001, NUREG-1953
Download: ML110680444 (3)

Text

N9UCLEAR EHEIGY IHSIITUTE Biff Bradley 4~2~ DIRECTOR RISKASSESSMENT

,/Jy~j~L~ 4 ZNUCLEAR GENERATION DIVISION February 23, 2011 / -=

Fl ~r1 Ms. Cindy K. Bladey Chief, Rules, Announcements and Directives Branch (RADB)

Office of Administration U.S. Nuclear Regulatory Commission NO Washington, DC 20555-0001 Cr n

Subject:

Industry Comments on Draft NUREG-1953, Confirmatory Thermal-HydraulicAnalysis Risk Models - Surry and Peach Bottom (FederalRegisterof November 10, 2010, 75 FR 69140-69141; Docket iD NRC-2010-0344).

Project Number: 689

Dear Ms. Bladey:

The subject FederalRegister notice issued for public comment a draft U.S. Nuclear Regulatory Commission Regulation NUREG document, Confirmatoty Thermal-HydraulicAnalysis Risk Models -

Surry andPeach Bottom. This draft NUREG documents in-depth analysis of the thermal-hydraulic aspects of the Standardized Plant Analysis Risk (SPAR) models for Surry and Peach Bottom, and suggests numerous changes to improve the consistency of the SPAR models with licensee-generated analyses.

The industry has reviewed the draft NUREG, and appreciates that the document both clearly summarizes the results and adequately details the specific analysis performed to arrive at those results. The industry also notes that several changes to the document could improve its clarity and ensure that future uses of the results are appropriate; comments regarding these changes are provided in an attachment. In addition to the comments provided in this attachment, NEI endorses the comments submitted by Exelon on December 15, 2010, and recommends that the NRC also carefully consider those comments prior to issuance of the final NUREG.

67 WW 5 t 1776 1Stieet, NW I Suite 400 1Washington, DC 1 20006-3708 1P: 202.739.8083 1 F:202ý533.0107 1 reb~nei.org I www.nel.org

Ms. Cindy K. Bladey February23, 2011 Page 2 We appreciate your consideration of the enclosed comments. If you have any questions or require additional information, please contact me at 202-739-8083; rebbneieorg or Victoria Anderson at vka(nei.oro; 202-739-8101.

Sincerely, Biff Bradley Attachment c: Mr. Kevin Coyne, NRC Mr. Donald Helton, NRC NRC Document Control Desk

ATTACHMENT Detailed Industry Comments on Draft NUREG-1953, Confirmatory Thermal-HydraulicAnalysis Risk Models - Surry andPeach Bottom Description of Major Plant Characteristics: In the description of the major plant characteristics in Section 4.1, it is suggested that for Surry, it be noted that successful sump recirculation function requires containment heat removal through the recirculation spray system.

Plant Representation in MELCOR: In describing the plant representation used for the study, it is stated that the core nodalization assumed 10 axial and 5 radial regions. Clarification of the sensitivity of this nodalization assumption would be helpful in illustrating its impact.

SLOCA Case Assumptions: It appears that accumulator injection was credited for all SLOCA cases discussed in this report; however, probabilistic risk assessments normally do not credit accumulator injection for SLOCA mitigation. The impact of this should be explored before issuance of the final NUREG.

Additional Sensitivities to Consider: While the work described in the draft NUREG involved extensive analysis evaluating sensitivities, the industry suggests two other sensitivities to consider.

The first is the impact of crediting manual actions to trip the Reactor Coolant Pumps in accordance with existing guidance, as such credit was not assumed in the analysis. The second suggested sensitivity that the, industry suggests evaluating is the impact of the Safety Relief Valves at Peach Bottom sticking open due to elevated gas temperatures, as the State-of-the-Art Reactor Consequence Analysis identified this as a significant sensitivity.