ML101450084

Request for Additional Information Regarding Licensee'S Final Safety Analysis Report Amendment Related to Reactor Systems, Nuclear Performance and Code Review, Ansd Plant Systems

ML101450084
Person / Time
Site:	Watts Bar
Issue date:	06/23/2010
From:	Joel Wiebe Watts Bar Special Projects Branch
To:	Bhatnagar A Tennessee Valley Authority
Wiebe, Joel NRR/DORL/WBSP, 415-6606
References
TAC ME2731
Download: ML101450084 (7)

Text

June 23, 2010 Mr. Ashok S. Bhatnagar Senior Vice President Nuclear Generation Development and Construction Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801

SUBJECT:

WATTS BAR NUCLEAR PLANT, UNIT 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSEES FINAL SAFETY ANALYSIS REPORT AMENDMENT RELATED TO REACTOR SYSTEMS, NUCLEAR PERFORMANCE AND CODE REVIEW, AND PLANT SYSTEMS (TAC NO. ME2731)

Dear Mr. Bhatnagar:

By letters dated November 24, 2009, December 14, 2009, and January 11, 2010, Tennessee Valley Authority (TVA) submitted Final Safety Analysis Report Amendments 95, 96, and 97, respectively.

The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the portion related to reactor systems, nuclear performance and code review, and plant systems and determined that further information is required to complete its assessment of TVAs submittals. In the enclosed request for additional information (RAI), the NRC staff has listed the requested information.

A response is required within 30 days of receipt of this letter.

If you should have any questions, please contact me at 301-415-6606.

Sincerely,

/RA/

Joel S. Wiebe, Senior Project Manager Watts Bar Special Projects Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-391

Enclosure:

RAI cc w/encl: Distribution via Listserv

Mr. Ashok S. Bhatnagar Senior Vice President Nuclear Generation Development and Construction Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801

SUBJECT:

WATTS BAR NUCLEAR PLANT, UNIT 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSEES FINAL SAFETY ANALYSIS REPORT AMENDMENT RELATED TO REACTOR SYSTEMS, NUCLEAR PERFORMANCE AND CODE REVIEW, AND PLANT SYSTEMS (TAC NO. ME2731)

Dear Mr. Bhatnagar:

By letters dated November 24, 2009, December 14, 2009, and January 11, 2010, Tennessee Valley Authority (TVA) submitted Final Safety Analysis Report Amendments 95, 96, and 97, respectively.

The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the portion related to reactor systems, nuclear performance and code review, and plant systems and determined that further information is required to complete its assessment of TVAs submittals. In the enclosed request for additional information (RAI), the NRC staff has listed the requested information.

A response is required within 30 days of receipt of this letter.

If you should have any questions, please contact me at 301-415-6606.

Sincerely,

/RA/

Joel S. Wiebe, Senior Project Manager Watts Bar Special Projects Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-391

Enclosure:

RAI cc w/encl: Distribution via Listserv DISTRIBUTION: RidsOgcRp Resource RidsRgn2MailCenter Resource PUBLIC RidsNrrDorlLpwb Resource RidsNrrDciCvib Resource LPWB Reading File RidsNrrLABClayton Resource RidsNrrPMWattsBar2 Resource RidsAcrsAcnw_MailCTR Resource RidsNrrDorlDpr RidsNrrDssSrxb RidsNrrDssSnpb RidsNrrDssSbpb ADAMS Accession No. ML101450084 OFFICE LPWB/PM LPWB/LA SRXB/BC SPNB/BC SBPB/BC OGC/NLO LPWB/BC (A)

NAME JWiebe BClayton AUlses AMendiola GCasto DRoth SCampbell DATE 06 / 01 /10 05 / 27/10 6 / 2 /10 6 / 2 /10 06 / 7/10 6 / 11 /10 6 / 23 /10 OFFICIAL AGENCY RECORD

REQUEST FOR ADDITIONAL INFROMATION WATTS BAR NUCLEAR PLANT, UNIT 2 FINAL SAFETY ANALYSIS REPORT AMENDMENTS 95, 96, and 97 TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-391 By letters dated November 24, 2009 (Agencywide Document and Management System Accession No. ML093370274), December 14, 2009 (ML093570464), and January 11, 2010 (ML100191426), Tennessee Valley Authority (TVA) submitted Final Safety Analysis Report (FSAR) Amendments 95, 96, and 97, respectively.

The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the portion related to reactor systems, nuclear performance and code review, and plant systems and determined that further information is required to complete its assessment of TVAs submittals. The following additional information is required to proceed with NRC staff review.

Reactor Systems (SRXB)

Question 1:

Section 5.2.2.4.2 of FSAR Amendment 97, Pressure Transient Analyses, includes an evaluation of low temperature overpressure transients (Section 5.2.2.4.2.1), but no evaluation of at-power overpressure transients. Please provide an evaluation of at-power overpressure transients, consistent with the guidelines of Section 5.2.2 of NUREG-0800.

Question 2:

As an incident of moderate frequency, the Inadvertent Operation of Emergency Core Cooling System event (reported in Section 15.2.14 of FSAR Amendment 90), must not generate a more serious plant condition without other faults occurring independently. To meet this requirement, Section 15.2.14 states that, Westinghouse currently uses the more restrictive criterion that a water-solid pressurizer condition be precluded when the pressurizer is at or above the set pressure of the pressurizer safety relief valves (PSRVs). This addresses any concerns regarding subcooled water relief through the plant PSRVs, which are not qualified for this condition. Should water relief through the pressurizer power-operated relief valves (PORVs) occur, the PORV block valves would be available, following the transient, to isolate the [reactor coolant system] RCS.

The NRC staffs position is outlined in Regulatory Issue Summary (RIS) 2005-29. Please provide an evaluation of the Inadvertent Operation of Emergency Core Cooling System event that is consistent with RIS 2005-29 and the guidelines of NUREG-0800, Rev 3.

Enclosure

Nuclear Performance and Code Review (SNPB)

All references to Watts Bar Nuclear Plant (WBN), Unit 1 are from the approved FSAR Amendment 7. All references to WBN Unit 2 are from Amendment 95 that is currently under review.

Chapter 4.1

1. Why is the density of fuel pellets different between WBN Unit 1 and WBN Unit 2 (compare Table 4.4-1 in each FSAR)?

2. Identify which control rods are being used, WBN Unit 2 FSAR makes multiple references to both Ag-In-Cd control rods and B4C with Ag-In-Cd tips. If WBN Unit 2 is transitioning from B4C with Ag-In-Cd tips (as approved in WBN Unit 1) to solely Ag-In-Cd control rods, provide justification for such a transition.

Chapter 4.2.1

1. Why is the yield strength correlation appropriate for irradiated cladding if the irradiated properties are attained at low exposures and the fuel/clad interactions that lead to minimum margin occur at much higher exposures?

2. In WBN Unit 2 FSAR Amendment 95 Section 4.2.1.2.2 under the heading Guide Thimble and Instrument Tube (p 4.2-8), should paragraph 3 read ZIRLO instead of Zircaloy?

3. Should the References given in Section 4.2.1.1.1 for WBN Unit 2 match those for WBN Unit 1?

a. Why is reference [25] removed from WBN Unit 1 FSAR, but used in WBN Unit 2 FSAR?

b. Why are [31], [32], and [35] referenced for WBN Unit 1 and not WBN Unit 2?

4. In WBN Unit 2 FSAR Amendment 95 Section 4.2.1.2.2 under the heading Grid Assemblies (p 4.2-9), should paragraph 5 read ZIRLO instead of Zircaloy?

5. In WBN Unit 2 FSAR Amendment 95 Section 4.2.1.3.1 under the heading Materials -

Fuel Cladding (p 4.2-10), should paragraph 3 read ZIRLO instead of Zircaloy?

6. In WBN Unit 2 FSAR Amendment 95 Section 4.2.1.3.2 under the heading Stresses and Deflections (p 4.2-17), should paragraph 1 read ZIRLO instead of Zircaloy?

Chapter 4.2.2

1. In WBN Unit 2 FSAR Amendment 95 Section 4.2.2.2 under the heading Upper Core Support Assembly (p 4.2-25), do the support columns also contain the thermocouple supports?

2. Have the changes to WBN Unit 2 FSAR Amendment 95 Table 3.9-5 been reviewed and approved?

Chapter 4.2.3

1. Confirm that the burnable absorber rods will be designed so that the absorber material will be maintained below 1492 °F and that the structural elements will be designed to prevent excessive slumping.

2. Does WBN Unit 2 have any part-length CRDMs?

3. FSAR Amendment 95 for WBN Unit 2 Table 4.1-1 (page 4.1-6) indicates the control rods for WBN Unit 2 are Ag-In-Cd. FSAR Amendment 7 for WBN Unit 1 Table 4.1-1 indicates the control rods for WBN Unit 1 are B4C with Ag-In-Cd tips. FSAR Amendment 95 for WBN Unit 2 Section 4.2.3.2.1 under the heading Rod Cluster Control Assembly indicates the control rods are identical to WBN Unit 1, B4C pellets, which are stacked on top of the extruded Ag-In-Cd slugs. Are the control rods in WBN Unit 1 and WBN Unit 2 the same, B4C with Ag-In-Cd tips, or does WBN Unit 2 have different control rods as indicated in Table 4.1-1 of its FSAR? Additionally, make the appropriate updates to WBN Unit 2s FSAR.

4. In WBN Unit 2 FSAR Amendment 95 Section 4.2.3.3.1, significant discussion is removed from the FSAR that describes the general methods of analysis, specific methods for analyzing the control rods, and specific methods for analyzing the burnable absorber rods. Provide justification for the reason of this removal, specifically addressing the removal of each paragraph.

5. In WBN Unit 2 FSAR Amendment 95 Section 4.2.3.3.1 (p 4.2-44), should paragraph 1 read ZIRLO instead of Zircaloy? If so, should the following calculation be performed for ZIRLO instead of Zircaloy?

6. WBN Unit 2 FSAR Amendment 95 section 4.2.3.4.1 (p 4.2-52) states:

The rod cluster control assemblies were functionally tested, following initial core loading but prior to criticality to demonstrate reliable operation of the assemblies. Each assembly was operated one time at no flow/cold conditions and one time at full flow/hot conditions. The assemblies were also trip tested at full flow/hot conditions. Those assemblies whose trip times fall outside a certain tolerance were tested an additional 3 times at full flow/hot conditions. Thus each assembly was adequately tested to verify that the assemblies are properly functioning.

WBN Unit 2 FSAR Amendment 95 section 4.2.3.4.2 (p 4.2-52) states:

These tests include verification that the trip time achieved by the control rod drive mechanisms meet the design requirement from start of rod cluster control assembly motion to top of dashpot. This trip time requirement was confirmed for each control rod drive mechanism prior to initial reactor operation, as required by Technical Specifications.

Was there an initial core loading for WBN Unit 2 such that this testing was completed? If not, address these two sections.

Plant Systems (SBPB)

RAI 10.4.1-1 In the 1982 Safety Evaluation (SE) for Watts Bar (NUREG-0847), the NRC staff observed that the three pressure zones for the main condenser are designed to produce a turbine back pressure of 1.5 (low pressure - LP), 2.15 (intermediate pressure - IP), and 3.065 (high pressure

- HP) inches of mercury for Units 1 and 2. In Amendment 7 of the WBN Unit 1 FSAR, those values are changed to 1.63 LP, 2.38 IP, and 3.40 HP. For the proposed FSAR for WBN Unit 2, the values for the three pressure zones are 1.92, 2.70, and 3.75 respectively. The NRC staff requests that TVA explain why the values for WBN Unit 1 and the proposed WBN Unit 2 pressure zones for the main condenser are different from the values indicated in the original SE.

RAI 10.4.1-2 In Amendment 7 to the WBN Unit 1 FSAR, TVA shows the Birmingham Wire Gauge (BWG) for the balance of tubes to be 22 BWG, whereas in the proposed WBN Unit 2 FSAR, this value is shown as 12 BWG. The NRC staff requests that TVA explain why WBN Unit 2 has a lower BWG value than WBN Unit 1.

RAI 10.4.1-3 In the original SE for WBN Unit 1 and 2, copper-nickel tubes were used to minimize corrosion and erosion of condenser tubes. In Amendment 7 to the WBN Unit 1 FSAR and the proposed WBN Unit 2 FSAR, the material is listed as SEACURE for tubes. The NRC staff requests that TVA confirm that the SEACURE material is the replacement for the copper-nickel tubing that was originally used for the condenser tubes.

RAI 10.4.1-4 In the original SE, the NRC staff noted that the main condenser design allows for water storage capacity for approximately 3 1/2 minutes of full-load operation. In the proposed WBN Unit 2 FSAR, this value is the same. However, in Amendment 7 of the WBN Unit 1 FSAR, the condenser is shown to handle water storage capacity of 3 minutes at full-load operation. The NRC staff requests that TVA explains the deviation of the WBN Unit 1 storage capacity from the proposed WBN Unit 2 storage capacity for the main condenser.

RAI 10.4.2-1 In the original SE (NUREG-0847), there are listed three mechanical vacuum pumps, an electrical heating coil, a HEPA filter, and a carbon absorber to comprise of the main condenser evacuation system (MCES). In Amendment 7 of the WBN Unit 1 FSAR and proposed FSAR for WBN Unit 2, TVA does not provide the full description of the components of the MCES, nor clarifies if the MCES still comprises of the same components as listed in the original SE, with

the exception of the vacuum pumps. The NRC staff requests that TVA provides a description of the components for the MCES for WBN Units 1 and 2.

RAI 10.4.2-2 In Amendment 7 to the WBN Unit 1 FSAR, TVA indicates that there are two types of radiation monitors for the vacuum pump exhaust. However, TVA describes the vacuum pump exhaust in the proposed WBN Unit 2 FSAR as having three types of radiation monitors. The NRC staff requests that TVA explains the reasoning for WBN Unit 2 having three radiation monitors versus WBN Unit 1 only having two radiation monitors.