ML11187A338

OL -

ML11187A338
Person / Time
Site:	Watts Bar
Issue date:	06/20/2011
From:	Office of Nuclear Reactor Regulation
To:	Division of Operating Reactor Licensing
References
Download: ML11187A338 (6)

Text

WBN2Public Resource From: Poole, Justin Sent: Monday, June 20, 2011 3:41 PM To: Crouch, William D Cc: garent@tva.gov; Bryan, Robert H Jr; WBN2HearingFile Resource Attachments: WB2-Audit-June.docx

Bill, Here is a draft version of the Audit plan for next weeks trip to Westinghouse. Please pass this on.

Justin C. Poole Project Manager NRR/DORL/LPWB U.S. Nuclear Regulatory Commission (301)4152048 email: Justin.Poole@nrc.gov 1

Hearing Identifier: Watts_Bar_2_Operating_LA_Public Email Number: 425 Mail Envelope Properties (19D990B45D535548840D1118C451C74D8CB267B7F1)

Subject:

Sent Date: 6/20/2011 3:40:56 PM Received Date: 6/20/2011 3:40:58 PM From: Poole, Justin Created By: Justin.Poole@nrc.gov Recipients:

"garent@tva.gov" <garent@tva.gov>

Tracking Status: None "Bryan, Robert H Jr" <rhbryan@tva.gov>

Tracking Status: None "WBN2HearingFile Resource" <WBN2HearingFile.Resource@nrc.gov>

Tracking Status: None "Crouch, William D" <wdcrouch@tva.gov>

Tracking Status: None Post Office: HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 270 6/20/2011 3:40:58 PM WB2-Audit-June.docx 22154 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

AUDIT PLAN for the SECOND AUDIT of WATTS BAR NUCLEAR PLANT UNIT 2, COMPLETION of LICENSING ACTIVITIES, DOCKET NO. 50-391 On March 15th, the SRXB staff conducted an audit at the applicants fuel vendor office in Rockville, Maryland, in order to understand the bases for certain accident analyses, reported in the applicants FSAR [1]. At that time, the vendor was unable to provide immediate responses to some of the staffs questions. Many of the responses, that were provided after the audit [2] [3],

were deemed by the staff to be incomplete and/or inadequate. Consequently, the SRXB staff requests a second audit at the applicants fuel vendor facility, in order to obtain the information the staff needs to complete its review.

This audit would give the staff access to material that might be proprietary in nature, to technical experts who are familiar with said material.

Audit Agenda The audit is scheduled to begin on June 28th at Westinghouses office in Cranberry, PA, and could continue for another three days (until July 1st).

Topics to be considered Steamline break analyses and methods The applicants analyses of the major steamline break, reported in Chapter 15 of the FSAR, indicate that the most severe case, identified as the 1.4 ft2 break, without offsite power available, produces a post-trip peak power level of three percent. The most severe case, in other plants of WB2s size and design, is identified as the 1.4 ft2 break, with offsite power available, and can produce a post-trip peak power level that is up to ten times greater. The staff plans to discuss these analyses with the applicants fuel vendor, Westinghouse, and review Westinghouses supporting documentation (e.g., topical reports, calculation notes, computer input and output, correspondence, and technical literature) in order to understand WB2s unexpected analytical results.

Mass addition event analyses and methods The analysis results of the inadvertent operation of the ECCS at power, and the CVCS malfunction events have been received, and appear to be in order. The audit will provide the staff an opportunity to review the analyses with the applicant and confirm the staffs understanding of the methods and results.

RCS and main steam system overpressure analysis

The results of WB2s overpressure analysis have also been received. The staff will review the analyses with the applicant and make any necessary clarifications. This part of the audit will be guided by SRP 5.2.2, Overpressurization Protection.

LOCA analyses and post-LOCA boron precipitation The applicants post-LOCA long-term core cooling and boric acid precipitation calculation will be reviewed and discussed, in order to assess its adequacy, and to determine whether further analysis is necessary to demonstrate compliance with 10 CFR 50.46.

The staff wishes to receive and review transient plots of the following parameters for the limiting large break LOCA (with respect to downcomer boiling) transient:

a. Downcomer level and fluid temperatures

b. Containment pressure

c. RCS pressure

d. Heat transfer coefficient at the hot spot

e. PCT

f. Sink Temperature at the PCI location

g. Core level

h. LPSI and HPSI injection mass flow rates

i. Heat transfer from the barrel wall and thermal shield

j. RWST temperature Westinghouse will also be asked to provide information, previously requested by the staff, which pertains to:

1. Condensation model and maximization of condensation 2 The effect of the time step size on the results, down to and including 0.001 sec.

3. Confirmation of the correct conductivity in the downcomer walls

4. Values for the lateral k-factors in the downcomer (e.g., based on Idlechik)

5. The decay heat multiplier used in the limiting large break LOCA analysis

6. The nodalization diagram for the WCOBR/TRAC model.

7. The WB2 specific analysis of a bottom-mounted instrument tube failure Watts Bar 2 incore system (WINCISE)

The audit will be used by the staff to discuss the information it has requested regarding the WINCISE, in order to gain the understanding it needs to complete its review of the system.

Audit Team The audit team will consist of:

Samuel Miranda, Reactor Systems Branch Anthony Mendiola, Branch Chief of Nuclear Performance Code Review Branch Leonard Ward, Nuclear Performance Code Review Branch Sunil Weerakkody, Deputy Director of Division of Safety Systems Paul Clifford, Division of Safety Systems And other reviewers that may be asked to attend by their branch chiefs The following support personnel are requested:

Licensing staff from the Tennessee Valley Authority (TVA)

A manager from the TVA with the authority to request supporting services from Westinghouse Cognizant staff engineers from Westinghouse Electric Company A manager from Westinghouse with the authority to supply the requested supporting services Documentation of Audit Within 45 days of the audit exit, the NRC staff will prepare a detailed audit report documenting the information reviewed during the audit, and any open items that might be outstanding after the audit. The audit report will be provided to the applicant in draft form for proprietary markup.

References

[1] NRC letter to TVA dated April 27, 2011, Watts Bar Nuclear Plant, Unit 2 - Audit Report of Westinghouse Documents Relating to Final Safety Analysis Report Accident Analyses (TAC NO. ME4620)

[2] TVA letter to NRC dated May 13, 2011, Watts Bar Nuclear Plant (WBN) Unit 2 -

Additional Responses to Request for Additional Information Regarding (1) Large Break Loss of Coolant Accident, (2) Steam Line Break, and (3) Miscellaneous Analysis

[3] TVA letter to NRC dated May 24, 2011, Watts Bar Nuclear Plant (WBN) Unit 2 -

Additional Responses to Request for Additional Information Regarding (1) Bottom Mounted Instrument (BMI) Tube Failure and (2) Mass Addition Events