ML102510313
| ML102510313 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 09/17/2010 |
| From: | Justin Poole Watts Bar Special Projects Branch |
| To: | Bhatnagar A Tennessee Valley Authority |
| Poole Justin/DORL/LPL3-1/ 301-415-2048 | |
| References | |
| TAC ME4074 | |
| Download: ML102510313 (5) | |
Text
September 17, 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 FINAL SAFETY ANALYSIS REPORT AMENDMENT RELATED TO SECTION 9.2 (TAC NO. ME4074)
Dear Mr. Bhatnagar:
By letter dated May 27, 2010 (Agencywide Documents Access and Management System Accession No. ML101610290), the Tennessee Valley Authority (TVA) submitted Final Safety Analysis Report (FSAR) Amendment No. 99 for Watts Bar Nuclear Plant (WBN), Unit 2. The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information provided by TVA in FSAR Amendment No. 99.
In an effort to complete the NRC staff review, enclosed is a request for additional information regarding FSAR Section 9.2 Component Cooling System.
A response is required by October 1, 2010.
If you should have any questions, please contact me at 301-415-2048.
Sincerely,
/RA/
Justin C. Poole, Project Manager Watts Bar Special Projects Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-391
Enclosure:
Request for Additional Information 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 FINAL SAFETY ANALYSIS REPORT AMENDMENT RELATED TO SECTION 9.2 (TAC NO. ME4074)
Dear Mr. Bhatnagar:
By letter dated May 27, 2010 (Agencywide Documents Access and Management System Accession No. ML101610290), the Tennessee Valley Authority (TVA) submitted Final Safety Analysis Report (FSAR) Amendment No. 99 for Watts Bar Nuclear Plant (WBN), Unit 2. The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information provided by TVA in FSAR Amendment No. 99.
In an effort to complete the NRC staff review, enclosed is a request for additional information regarding FSAR Section 9.2 Component Cooling System.
A response is required by October 1, 2010.
If you should have any questions, please contact me at 301-415-2048.
Sincerely,
/RA/
Justin C. Poole, Project Manager Watts Bar Special Projects Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-391
Enclosure:
Request for Additional Information cc w/encl: Distribution via Listserv DISTRIBUTION:
RidsOgcRp Resource RidsRgn2MailCenter Resource PUBLIC RidsNrrDorlLpwb Resource RidsNrrDssSbpb Resource LPWB Reading File RidsNrrLABClayton Resource RidsNrrPMWattsBar2 Resource RidsAcrsAcnw_MailCTR Resource RidsNrrDorlDpr GPurciarello, NRR ADAMS Accession No. ML102510313
- via memo OFFICE LPWB/PM LPWB/LA SBPB/BC OGC LPWB/BC NAME JPoole BClayton GCasto*
DRoth/NLO SCampbell DATE 09 / 08 /10 09 / 08 /10 9/6/10 09 / 15 /10 09 / 17 /10 OFFICIAL AGENCY RECORD
Enclosure REQUEST FOR ADDITIONAL INFROMATION WATTS BAR NUCLEAR PLANT, UNIT 2 FINAL SAFETY ANALYSIS REPORT AMENDMENT 99 TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-391 RAI CCS-1 Watts Bar Nuclear Plant (WBNP), Units 1 and 2, are apparently designed such that if a design basis accident occurred in one unit, the other, non accident unit would be placed in hot standby.
This is stated in the following Final Safety Analysis Report (FSAR) Sections:
FSAR Section 9.2.2.4, Safety Evaluation, which states:
Design basis safe shutdown for Watts Bar Nuclear is the hot standby mode. If one unit is in an accident condition, the other unit should be maintained at hot standby (if it can not be maintained in its operating mode) until the accident unit cooldown is accomplished.
FSAR Section 9.2.2.2, System Description, which states:
(1) If the non-accident unit is utilizing RHR [Residual Heat Removal] cooling it will be necessary to close the CCS [Component Cooling System] supply to these heat exchangers. RHR cooling will be terminated when the non-accident unit is in RHR cooldown with the reactor coolant system not vented.
However, FSAR Section 3.1.2, WBNP Conformance with GDCs [General Design Criteria],
WBNP states their intent in meeting Title 10 of the Code of Federal Regulations Part 50 Appendix A, GDC 5.
GDC 5 states:
Criterion 5--Sharing of structures, systems, and components. Structures, systems, and components important to safety shall not be shared among nuclear power units unless it can be shown that such sharing will not significantly impair their ability to perform their safety functions, including, in the event of an accident in one unit, an orderly shutdown and cooldown of the remaining units.
The CCS and the Essential Raw Cooling Water System (ERCW) will each be a shared system between Unit 1 and Unit 2 and are used in plant shutdown and cooldown. In the event of an accident in one unit, the CCS and ERCW should be capable of performing their safety functions for the accident unit and an orderly shutdown and cooldown of the non-accident unit per GDC 5.
While FSAR Section 3.1.2 expresses the licensees intent to comply with GDC 5, it appears in FSAR Sections 9.2.2.4 and 9.2.2.2 the units do not comply with GDC 5.
Furthermore, in a possible scenario where both units are required to enter Technical Specification (TS) 3.0.3 at approximately the same time, the capacity to cooldown both units within 37 hours4.282407e-4 days <br />0.0103 hours <br />6.117725e-5 weeks <br />1.40785e-5 months <br /> will be necessary.
Explain how the CCS and ERCW meet the requirements of GDC 5 and are capable of meeting the requirements of TS 3.0.3 if both units enter TS 3.0.3 simultaneously. Discuss existing analysis and calculations that show that these requirements are met to include the heat loads and CSS flow requirements for each CSS load. The staff requests that the applicant provide the above described design basis for the CCS and update the FSAR accordingly.
RAI CCS-2 The FSAR under Section 9.2.2.2, System Description, describes some operations for Unit 1 operation only. With the licensing of Unit 2, why is there a distinction for Unit 1 operation only?
Please clarify why WBN is making this distinction for Unit 1 and not for Unit 2 and revise the FSAR accordingly.
RAI CCS-3 Section 9.2.2.4, Safety Evaluation, states:
The CCS is comprised of two independent trains (A&B) where the B train header and C heat exchanger serve the Unit 1 Train B engineered safeguards equipment, and the Train A header and Heat Exchanger A serve Unit 1 miscellaneous equipment. Heat Exchanger B serves Unit 2. Each train has the capability to provide the maximum cooling water requirement for the plant.
As stated above, the B train header and C heat exchanger serve the Unit 1 Train B engineered safeguards equipment. What serves the Unit 2 Train B engineered safeguards equipment (ESF)? Please explain.
As stated above, the Train A header and Heat Exchanger A serve Unit 1 miscellaneous equipment. What serves the Unit 1A ESF loads? Please explain.
As stated above, Heat Exchanger B serves Unit 2. What part of Unit 2 does it serve? Unit 2A ESF? Unit 2B ESF? Please explain.
As stated above, The CCS is comprised of two independent trains (A&B). Define the boundaries of each train and revise the FSAR to clearly explain the boundaries.
The applicant needs to answer the questions above and make applicable changes to the FSAR.
RAI CCS-4 The guidance in Standard Review Plan (SRP) 9.2.2 (Sections III.1 and III.6) state that the safety analysis report is to provide information to identify minimum heat transfer and flow requirements for normal plant operations and minimum heat transfer and flow requirements for each accident situation for the required time spans. The information is useful in determining whether the applicant has met the requirements of GDC 44, Cooling water.
The applicant has stated in Section 9.2.2.4 of the FSAR that, Sufficient cooling capacity is provided to fulfill system requirements under normal and accident condition. The applicant has not identified the minimum flow and heat transfer requirements for each load for each accident situation for the required time spans. The Nuclear Regulatory Commission staff does not consider this sufficient information to meet the regulatory guidance as stated above.
The applicant needs to provide minimum flow and heat transfer requirements for each load supplied by the CCS for normal plant operations and for each applicable design-basis accident, including a design basis accident in one unit and a shutdown and cooldown of the non-accident unit.
RAI CCS-5 SRP 9.2.2, Reactor Auxiliary Cooling Water System, states in Section III. Review Procedures, that automatically operated isolation valves separate nonessential portions and components from essential portions. Yet FSAR Section 9.2.2.2, System Description, states that, In event of an accident, non-safety related components are not required: therefore, CCS flow to these components may be manually isolated.
Explain why the CCS as described in the FSAR does not meet the guidelines specified in SRP 9.2.2 regarding automatically isolating nonessential loads during an accident.