ML101610689

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OL - for Your Review - Watts Bar Unit 2 - Preliminary RAIs - Snpb
ML101610689
Person / Time
Site: Watts Bar Tennessee Valley Authority icon.png
Issue date: 06/10/2010
From:
Office of Nuclear Reactor Regulation
To:
Division of Operating Reactor Licensing
References
Download: ML101610689 (5)
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Text

1 WBN2Public Resource From:

Lamb, John Sent:

Thursday, June 10, 2010 12:31 PM To:

Arent, Gordon; wdcrouch@tva.gov Cc:

WBN2HearingFile Resource; Raghavan, Rags; Milano, Patrick; Wiebe, Joel; Haag, Robert

Subject:

For Your Review - Watts Bar Unit 2 - Preliminary RAIs - SNPB Attachments:

Prelim SNPB RAI - 4 3 & 4 4.docx Gordon & Bill, Attached, for your review, are preliminary Request for Additional Information (RAI) questions regarding Watts Bar Nuclear Plant (WBN), Unit 2. Please review to ensure that the RAI questions are understandable, the regulatory basis is clear, there is no proprietary information contained in the RAI, and to determine if the information was previously docketed. Please also let me know how much time Tennessee Valley Authority (TVA) needs to respond to the RAI questions.

Thanks.

John

Hearing Identifier:

Watts_Bar_2_Operating_LA_Public Email Number:

21 Mail Envelope Properties (BE1CC4A72435624D84F8699734202B3E1FAC07F809)

Subject:

For Your Review - Watts Bar Unit 2 - Preliminary RAIs - SNPB Sent Date:

6/10/2010 12:30:49 PM Received Date:

6/10/2010 12:30:54 PM From:

Lamb, John Created By:

John.Lamb@nrc.gov Recipients:

"WBN2HearingFile Resource" <WBN2HearingFile.Resource@nrc.gov>

Tracking Status: None "Raghavan, Rags" <Rags.Raghavan@nrc.gov>

Tracking Status: None "Milano, Patrick" <Patrick.Milano@nrc.gov>

Tracking Status: None "Wiebe, Joel" <Joel.Wiebe@nrc.gov>

Tracking Status: None "Haag, Robert" <Robert.Haag@nrc.gov>

Tracking Status: None "Arent, Gordon" <garent@tva.gov>

Tracking Status: None "wdcrouch@tva.gov" <wdcrouch@tva.gov>

Tracking Status: None Post Office:

HQCLSTR01.nrc.gov Files Size Date & Time MESSAGE 520 6/10/2010 12:30:54 PM Prelim SNPB RAI - 4 3 & 4 4.docx 30616 Options Priority:

Standard Return Notification:

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Recipients Received:

PRELIMINARY REQUEST FOR ADDITIONAL INFORMATION FOR WATTS BAR NUCLEAR PLANT, UNIT 2 TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-391 Below, for your review, are preliminary Request for Additional Information (RAI) questions regarding Watts Bar Nuclear Plant (WBN), Unit 2. Please review to ensure that the RAI questions are understandable, the regulatory basis is clear, there is no proprietary information contained in the RAI, and to determine if the information was previously docketed. Please also let me know how much time Tennessee Valley Authority (TVA) needs to respond to the RAI questions.

By letters dated November 24, 2009 (Agencywide Document Access and Management System Accession No. ML093370274), TVA submitted Final Safety Analysis Report (FSAR)

Amendment No. 95. The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information provided by the TVA in FSAR Amendment No. 95.

Nuclear Performance and Code Review (SNPB)

All references to WBN Unit 1 are from the approved FSAR Amendment No. 7. All references to WBN Unit 2 are from Amendment No. 95.

Chapter 4.3.2

1. Discuss the initial core loading strategy for WBN Unit 2.
2. In Table 4.3-1 (p 4.3-40) define the two numbers given for the following in the Fuel Assemblies section:
a. Diameter of Guide Thimbles (upper part)
b. Diameter of Guide Thimbles (lower part)
c. Diameter of Instrument Guide Thimbles
3. In Table 4.3-1 (p 4.3-40) should the Clad Material under the section Fuel Rods read ZIRLO instead of Zircaloy?
4. Table 4.3-1 (p 4.3-41) in the Rod Cluster Control Assemblies section has information which looks to be carried over from WB1 which is no longer used in WB N Unit 2, such as the information for the boron carbide (B4C) control rods. According to the table, B4C control rods will not be used in WBN Unit 2, but all of the parameters are still provided in the table. Correct the table to make it consistent with the Rod Cluster Control Assemblies which will be used in WBN Unit 2.
5. In WBN Unit 2 Amendment No. 95 section 4.3.2.2.4, the definition of axial offset (p 4.3-10), differs from the definition of axial offset from WBN Unit 1 UFSAR Amendment No.7 section 4.3.2.2.4. Which definition is correct?
6. In WBN Unit 2 Amendment No. 95 section 4.3.2.2.5, show the equation used to determine the average linear power.
7. In WBN Unit 2 Amendment No. 95 section 4.3.2.2.5, the total core power is assumed to be limited to 118-percent by a reactor trip, but WBN Unit 1 assumes the total core power to be limited by 121-percent by reactor trip. Provide an explanation for this difference.
8. In WBN Unit 2 Amendment No. 95 section 4.3.2.2.6, describe the impacts of using BEACON with fixed incore detectors on the uncertainties listed in this section. Discuss any other impacts of using BEACON with fixed and not moveable incore detectors. Has BEACON been implemented with fixed detectors in other cores?
9. In WBN Unit 2 Amendment No. 95 section 4.3.2.3.2, when the moderator coefficient is calculated for the various plant conditions, is the moderator temperature varied by adding 5°F to each of the mean temperatures, or by adding and subtracting 5°F to each of the mean temperature (p 4.3 4.3-18)?
10. In WBN Unit 2 Amendment No. 95 section 4.3.2.4.2, what is 4EF (p 4.3-20)?
11. In WBN Unit 2 Amendment No. 95 section 4.3.2.8.5 and section 4.3.3.2, LEOPARD is referenced as reference 17, however, according to the references section, Reference 17 was deleted by Amendment 92. Why was the amendment deleted?

Chapter 4.3.3

1. In WBN Unit 2 Amendment No. 95 section 4.3.3.2, should reference 57 from WBN Unit 1 Chapter 4.3 be added to identify which ENDF/B-VI files are being specified (p 4.3-34)?
2. In WBN Unit 2 Amendment No. 95 section 4.3.3.3, should the reference to Section 4.3.2.2.7 be to Section 4.3.2.2.6 instead?

Chapter 4.4.1

1. In WBN Unit 2 Amendment No. 95 section 4.4.1.1 under the heading Discussion (p 4.4-1), change DBN to DNB.
2. In WBN Unit 2 Amendment No. 95, Table 4.4-1 is inconsistent with Table 4.1-1. Why are the tables inconsistent?

Chapter 4.4.2

2. In WB2 Amendment 95 page 4.4-11, there are multiple locations on the right hand side of the page where equation numbers are pasted in the middle of paragraphs blocking the view of the words. Correct these errors.
3. Confirm that WBN Unit 2 is limited to cores with only RFA-2 fuel and will not use any other type of fuel until an approved transition core methodology is submitted.
4. In WBN Unit 2 Amendment No. 95 section 4.4.2.5, the conclusion is drawn that the minimum DNBR in the hot channel is relatively insensitive to variations in void models.

This conclusion is based on a sensitivity study using the THINC-IV code (which is

Reference 52 of the FSAR). The THINC-IV sensitivity study (Section 5.5 in Reference

52) uses void models than will be used in VIPRE. What, then, is the basis for assuming that the sensitivity study remains applicable to the VIPRE-01 code?
5. In WBN Unit 2 Amendment No. 95 page 4.4-18, there are multiple locations on the right hand side of the page where equation numbers are pasted in the middle of paragraphs blocking the view of the words. Correct these errors. Additionally, these changes to this page were not captured and the page is marked WBNP-73 which signifies it is from Amendment No. 73 and it is not.

Chapter 4.4.3

1. In WBN Unit 2 Amendment No. 95 section 4.4.3.1.3, clarify the first sentence which references the VIPRE-01 THINC-IV computer code.
2. In WBN Unit 2 Amendment No. 95 section 4.4.3.2.1 on page 4.4-23, the definition of FN H should be the definition of FRTP H.
3. In WBN Unit 2 Amendment No. 95 page 4.4-25, there is one location on the right hand side of the page where equation numbers are pasted in the middle of paragraphs blocking the view of the words. Correct this error.

Chapter 4.4.5

1. In WBN Unit 2 Amendment No. 95 section 4.4.5.1, the figure referred to is Figure 4.4-5.

In WBN Unit 2 Amendment No. 98 section 4.4.5.1 the figure referred to is Figure 4.4.6.

While there is a change in the figure number between the two amendments, Amendment No. 98 has the page marked as WBNP-95 which means there have been no changes since Amendment No. 95. What are the criteria that would signify a change and cause the page to be marked WBNP-98?

Quality Assurance RAI

1. The NRC staff has identified multiple inconsistencies, discrepancies, and factual errors in review of WBN Unit 2 Amendment No. 95. Most of the errors identified were inconsistencies (referring to Zircaloy instead of ZIRLO), but some were quite substantial (references to both Ag-In-Cd control rods and B4C with Ag-In-Cd tips, reference to startup testing performed on the rod cluster control assemblies of WBN Unit 2, discrepancies between Table 4.4.1 and Table 4.1.1). TVA submitted Amendment No.

98 to correct the errors in Amendment Nos. 95 and 97, but none of substantial errors identified by the NRC staff were identified or corrected by Amendment No. 98 errors.

Please describe the quality control and assurance process applied to the information contained in Amendment No. 95 (and Amendment No. 98). Explain what assurance TVA can provide the NRC staff that the information contained in the Amendments is factually correct, given the number and magnitude of identified discrepancies and errors identified by the NRC staff. If left uncorrected (especially the discrepancies between Table 4.4.1 and Table 4.1.1) what would the impact of the errors be?

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