ML081440107

Requests for Additional Information on STP 3 & 4 Cola

ML081440107
Person / Time
Site:	South Texas, 05200012, 05200013
Issue date:	05/20/2008
From:	Richards K South Texas
To:	Document Control Desk, Office of New Reactors
References
+reviewedgfw, ABR-AE-08000037
Download: ML081440107 (14)

Text

Nuclear Operating Company South Texas ProLect Electric GeneratinqStation PO gox28,9 adsworth, Tes 774.83 AA,-

May 20, 2008 ABR-AE-08000037 10 CFR 52 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville MD 20852-2738 South Texas Project Units 3 and 4 Docket Nos.52-012 and 52-013 Requests for Additional Information on STP 3 &4 COLA Attached are responses to Nuclear Regulatory Commission Request for Additional Information letter numbers 05, 06, 12, 13, 14 and 22 related to Part 2, Tier 2, Sections 10.3 and 10.4. This submittal includes responses to Question numbers 10.03-1, 10.03-2, 10.04.01-1, 10.04.03-1, 10.04.03-2 and 10.04.03-3. When a change to the COLA is indicated by a question response, the change will be incorporated into the next routine revision of the COLA following NRC acceptance of the question response.

There are no new commitments made in this letter.

If you have any questions, please contact Greg Gibson at (361) 972-4626 or Bill Mookhoek at 361-972-7274.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on 562O O' /Jo /s Kevin Richards Group Vice President South Texas Project, Units 3 & 4 gsc Attachments

1. Question 10.03-1

2. Question 10.03-2

3. Question 10.04.01-1

4. Question 10.04.03-1

5. Question 10.04.03-2

6. Question 10.04.03-3 7_Lx 7

ABR-AE-08000037 Page 2 of 2 cc: w/o attachment except*

(paper copy) (electronic copy)

Director, Office of New Reactors U. S. Nuclear Regulatory Commission Loren R. Plisco One White Flint North U. S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852-2738 Thad Hill Marty Ryan Regional Administrator, Region IV Harry Holloway U. S. Nuclear Regulatory Commission Steve Winn 611 Ryan Plaza Drive, Suite 400 Brad Porlier Arlington, Texas 76011-8064 Eddy Daniels NRG South Texas 3/4 LLC Richard A. Ratliff Bureau of Radiation Control Jon C. Wood, Esquire Texas Department of State Health Services Cox Smith Matthews 1100 West 49th Street Austin, TX 78756-3189 J. J. Nesrsta R. K. Temple C. M. Canady Kevin Polio City of Austin L. D. Blaylock Electric Utility Department CPS Energy 721 Barton Springs Road Austin, TX 78704

• Steven P. Frantz, Esquire A. H. Gutterman, Esquire Morgan, Lewis & Bockius LLP 1111 Pennsylvania Ave. NW Washington D.C. 20004

• George F. Wunder Two White Flint North 11545 Rockville Pike Rockville, MD 20852

Question 10.03-1 ABR-AE-08000037 Attachment 1 Page 1 of 2 Question 10.03-1 QUESTION:

The SRP Section 10.3: Main Steam System Section 10.3.7.1, "Procedures to Avoid Steam Hammer and Discharge Loads," of the ABWR DCD (design Certification Document) states that the COL applicant will provide operating and maintenance procedures that include adequate precautions to avoid steam hammer and discharge loads. Also, Section 10.3.3, "Evaluation," of the DCD describes that all components and piping for the main steam supply system (MSSS) are designed in accordance with the codes and standards listed in Section 3.2 of the DCD to insure that the MSSS accommodates operational stresses resulting from static and dynamic loads, including steam hammer and normal and abnormal environmental conditions. Additionally, SRP Section 10.3, Item 1.5, "COL Action Items and Certification Requirements and Restriction," describes that for a COL application referencing a DC, a COL applicant must address COL action items included in the referenced DC. Further, Item 2 of "SRP Acceptance Criteria" (SRP Section 10.3, Item I), describes that the system (MSSS) should adequately consider water (steam) hammer and relief valve discharge loads to assure that system safety functions can be performed and should assure that operating and maintenance procedures include adequate precautions to prevent water (steam) hammer and relief valve discharge loads. However, the site specific supplement provided in the COL application (i.e., FSAR Section 10.3.7.1) does not provide these procedures for NRC staffs review, as stated in this COL license information item. In order to ensure the adequacy of the MSSS and its compliance with the criteria in the SRP and the DCD, please provide these procedures for staffs review and evaluation. Also, explain the elements of these procedures and how they comply with the SRP criteria and the codes and standards identified in Section 3.2 of the DCD.

RESPONSE:,

FSAR Section 10.3.7.1 does address the COL action item in ABWR DCD Tier 2 Section 10.3.7.1, which in turn addresses the provision in SRP Section 10.3, SRP Acceptance Criterion 2. Specifically, FSAR Section 10.3.7.1 states that "Operating and maintenance procedures that include precautions to avoid steam hammer and relief valve discharge loads are prepared in accordance with the Plant Operating Procedures Development Plan described in Subsection 13.5.3.1."

At the COL application stage of the project, it is neither necessary nor appropriate to develop and issue operating and maintenance procedures. For example, with respect to operating procedures in general, Regulatory Guide 1.206, Section C.1.13.5 states: "Ingeneral, the FSAR is not expected to include detailed written procedures. The FSAR should provide a brief description of the nature and content of the procedures and a schedule for the preparation of appropriate written administrative procedures (see Section 13.5.1.1)." This general provision is applicable to the operating and maintenance procedures related to steam hammer and relief valve discharge loads. STPNOC will supplement FSAR Section 10.3.7.1, as indicated below:

Question 10.03-1 ABR-AE-08000037 Attachment 1 Page 2 of 2 10.3.7.1 Procedures to Avoid Steam Hammer and Discharge Loads The following site-specific supplement addresses COL License Information Item 10.4.

Operating and maintenance procedures that include precautions to avoid steam hammer and relief valve discharge loads are prepared in accordance with the Plant Operating Procedure Development Plan described in Subsection 13.5.3.1. These precautions include a sufficiently Iong main steam line warm-up period, including a turbine soaking period, during which the low point drain 1 valves are opened to ensure that no condensed steam remains in the main steam lines. 1-7

,when the drain valves are closed. Additionally, maintenance procedures provide for the routine inspection of the low point drain collection pots to ensure that they are operating properly.

Question 10.03-2 ABR-AE-08000037 Attachment 2 Page 1 of 2 Question 10.03-2 QUESTION:

In FSAR Section 10.3, "Main Steam System," standard departure STD DEP 10.3-1, "Main Steam Line Drains," expands the discussion from the ABWR DCD, to state that the main steam system also serves as the "alternative leakage path" to contain the radioactive steam which passes the main steam isolation valves before they close to isolate the reactor under emergency conditions. STD DEP 10.3-1 provides information concerning the alternate leakage path that does not appear to be consistent with the information provided in ABWR DCD/Tier 2, Section 3.2.5.3, "Main Steam Line Leakage Path." Also, some of the information that is characterized as a departure is already reflected in DCD Section 3.2.5.3 and it is not clear why this information is included in the proposed departure; the proposed departure refers to "alternate leakage path" and it is not clear why the term "alternate" is used; and it is not clear whether any credit is taken for plate-out in the steam line drains. Therefore, the staff requests the .applicant to provide additional information and be more clear and specific with respect to the departure that is being proposed for the main steam system.

RESPONSE

No performance change to the DCD wording for this function was intended. The addition of the term "alternate" to the phrase "main steam line leakage path" was made in error. STD DEP 10.3-1 is intended to address main steam isolation valve closure (to isolate the reactor) under emergency conditions. Any leakage past the closed main steam isolation valves which will flow in the main steam lines and the main steam drain lines downstream of the corresponding containment isolation valves will be contained. The means of containment is the main steam lines from the containment isolation valves to the turbine stop valvesi the bypass lines from the containment isolation valves to the condenser, the main steam drain lines to the condenser and other main steam lines larger than 2 2inches (e.g. steam lines to the SJAE) up to their automatic isolation valves, and the condenser. Section 15.6.5.5.1.2 (Tier 2 of the DCD) includes plate-out of the steam line drains and condenser as part of fission product release and pathway to the environment modeling.

The wording following the first paragraph in FSAR Section 10.3.2.1 will be revised as follows:

STD DEP 10.3-1 The drains from the steamlines inside containment are connected to the steamlines outside the containment to permit equalizing pressure across the MSIVs during startup and following a steamline isolation.

Question 10.03-2 ABR-AE-08000037 Attachment 2 Page 2 of 2 The Main Steam System ...... r..e. a"c tho "alt'rnato loaktaao path" t6 contains the radioactive steam which passes the main steam isolation valves before they close to isolate the reactor under emergency conditions. This function of containinq steam is done by the main steam piping, turbine bypass piping and steam drain piping discharging to the condenser.

In ardo.r to~ cro acan "altrrnAto loakageo path." t The main steam piping and branch lines, 2-1/2 inches in diameter and larger, from (but not including) the outboard MSIVs to the turbine stop valves and to the turbine byvass valves are Quality Group B in accordance with the construction and quality requirements, ASME B&PV,Section III, Division 1, Subsection NC-Class 2, Nuclear Plant Components. The main steam lines from the seismic restraint on the outboard side of the outermost MSIVs, and all branch lines 2-1/2 inches in diameter and larger (including lines and valve supports), are designed by the use of an appropriate dynamic seismic system analysis, to withstand the safe shutdown earthquake (SSE) design loads for the ABWR standard plant in combination with other appropriate loads, within the limits specified for Class 2 pipe in Section III of the ASME B&PV Code. Lines smaller than 2-1/2 inches in diameter, the rupture of which could result in bypass of the main condenser, are designed to withstand the SSE design loads for the ABWR standard plant in combination with other appropriate loads. The mathematical model for the dynamic and seismic analyses of the main steam lines and branch line piping includes the turbine stop valves and piping to the turbine casing.

In addition to these changes, STD DEP 10.03-1 in Part 7, Section 3.0 will be revised to address main steam isolation valve closure under emergency conditions, and to remove reference to an "alternate leakage path" as follows:

STD DEP 10.3-1, Main Steam Line Drains Subsection 10.3.2.1 of the reference ABWR DCD states that the drains from the steamlines inside containment are connected to the steamlines outside the containment to permit equalizing pressure across the MSIVs during startup and following a steamline isolation. STP FSAR Subsection 10.3.2.1 expands that discussion i state that the Main Steam System seo corvo. as the ,at.rnto ... a.! !j-contains the radioactive steam which passes the main steam isolation valves before they close to isolate the reactor under emergency conditions. 'The,dos

~~j~~7idcc8.@

tho!daaicfdointhtpr'da the AlitQ Rnat ngt~~h7, This departure has been evaluated and determined to comply with the requirements in 10 CFR 52, Appendix A, Section VIII.B.5, as described previously. The change has no adverse impact.

Question 10.04.01-1 ABR-AE-08000037 Attachment 3 Page 1 of 2 Question 10.04.01-1 QUESTION:

Section 10.4.1.2.1, "General Description," of the ABWR DCD describes the main condenser (MC) as a multi-pressure, three-shell, reheating/deaerating unit. The DCD design is modified by STD DEP 10.4-2 in the South Texas Project (STP) RCOL application which states: "The main condenser is a single pass, single pressure, three-shell, deaerating unit." The departure also indicates that the three condenser shells are cross-connected to equalize pressure. In accordance with Standard Review Plan (SRP) Section 10.4.1, Item 111.3.D, design provisions have been incorporated into the MC that will preclude component or tube failures due to steam blowdown from the turbine bypass system. Also, General Design Criteria (GDC) 60 states, "The nuclear power unit design shall include means to control suitably the release of radioactive materials in gaseous and liquid effluents and to handle radioactive solid waste produced.

during normal 'reactor operation, including anticipated operational occurrences. Sufficient holdup capacity shall be provided forretention of gaseous and liquid effluents containing radioactive materials ...... In order to conform to the SRP Section 10.4.1 guidance and the GDC 60 criteria, please explain the impact of the temperature and pressure surges in the main condenser on the low pressure turbine and condenser internals during the most limiting turbine steam bypass event, including the maximum temperature and pressure that is reached compared to the maximum design values, the impact of blowdown and transient effects on condenser internals, and limiting assumptions that apply. Also, explain how the main condenser design capability for the most limiting case will be confirmed during preoperational testing. In addition, Table 10.4-1, "Condenser Design Data," in Chapter 10, Section 4, of the FSAR indicates that the full power main condenser shell pressure for the STP design is 9.38 kPaA when the circulating water temperature is 32.2 'C. However, Figure 10.1-3, "Reference Heat Balance for Valves Wide Open," in Chapter 21, Section 4 of the STP FSAR shows that the pressure of the main condenser as 6.37 kPa and the rated turbine exhaust pressure as 6.77 kPa. Please explain this apparent inconsistency and confirm that the main condenser shell design pressure range of 0 to 207 kPaA that is specified in the above Table 10.4-1 continues to apply to the STP main condensers. Also, please clarify which pressures are absolute and which are gauge.

RESPONSE

Impact of the Steam Bypass Discharge on the LP Turbine and Condenser Internals The impact on the LP turbine and condenser internals due to steam dump from the steam bypass valves is minimized by design as follows:

" The Main Condenser spray system provides a protective water curtain between the turbine components and the bypass line to shield the turbine from the bypass steam. Main condenser spray is initiated based on Turbine Bypass Valve open signal.

" Bypass steam is admitted to the condenser above the tube bundle and below the low pressure feed water heaters which are installed in the condenser neck. The bypass steam discharge inside the condenser is in the form of a perforated header. The steam exit velocity from the perforated header is expected to be sonic; therefore, condenser internal support members are designed and routed considering the bypass steam jet impingement impact and temperature effect.

Additionally, tubes located at the top of the tube bundle are designed to withstand the resulting velocities and temperatures.

Question 10.04.01-1 ABR-AE-08000037 Attachment 3 Page 2 of 2 Pre-Operational Testing to Verify Condenser Capacity during Bypass Steam Dump "The Bypass Steam system consists of three headers; each routed to one of the three condenser shells.

"The initial test program procedures require thatone of the bypass steam headers be allowed to discharge into the condenser at 75% rated load. At this load, the main steam inlet pressure to the turbine and the bypass flow rate are expected to be at their maximum design values. The procedures also require that the selected header remain open for 5 minutes to verify that no adverse transient conditions could result.

"Following testing, the condenser internal components are visually inspected for any significant damage or erosion.

Condenser Pressure at Low CW Temperatures.

- Table 10.4-1 indicates condenser capability design pressure of 9.38 kPaA which corresponds to the condenser design pressure calculated by turbine heat balance at rated thermal power. The pressure values of 6.37kPaA and 6.77 kPaA indicated in Figure 10.1-3 represent the condenser pressure and turbine exhaust pressure each at the guaranteed condition. Both pressures are absolute.

Condenser Shell Design Pressure.

The condenser shell is designed for a pressure range of 0 to 207 kPaA. The upper value is determined based on the hydrostatic pressure test performed in accordance with the Heat Exchange Institute Standard for steam surface condensers, 9th Edition addenda (equivalent to 15 psig)

No COLA revision is required as a result of this RAI response.

Question 10.04.03-1 ABR-AE-08000037 Attachment 4 Page 1 of 2 Question 10.04.03-1 QUESTION:

The staff reviewed STP COL FSAR Section 10.4.3.2.2, "System Operation," which contains a modification to the ABWR DCD. The modification states, "The seal steam header pressure is regulated automatically by the sealing steam pressure regulator. Pressure is controlled at approximately 27.6 kPaG. Relief valves protect the sealing steam header from overpressure." The inclusion of a specific controller operating pressure of 27.6 kPaG is an addition to information provided in the ABWR DCD and is without basis or comment on how this approximate pressure was obtained. NUREG-800 Standard Review Plan (SRP)

Section 10.4.3, Item 111.1 specifies that the piping and instrumentation diagrams reflect the source of sealing steam and the disposition of steam and noncondensables vented from the gland seal. In conjunction, General Design Criteria (GDC) 60 from 10 CFR 50, Appendix A, "Control of Releases of Radioactive Materials to the Environment," requires control of liquid and gaseous radioactive effluents and handling of radioactive solid wastes. In order to comply with the SRP Section 10A4.3 criteria and the GDC 60 requirements, the staff requests the applicant to provide additional information sufficient to demonstrate the basis for the controller operating pressure of 27.6 kPaG and how this design objective controls the release of radioactive material from the turbine gland sealing system.

RESPONSE

Basis for controller operating pressure:

Each turbine gland requires sufficient steam to seal. The larger the gland clearance, the greater the steam flow required to seal the gland. Approximately 11 kPaG of steam header pressure is required to supply sufficient steam flow to the maximum clearance gland. The 27.6 kPaG controller operating pressure provides sufficient margin to the required 11 kPaG.

How this design objective controls the release:

The high pressure turbine gland one-line drawing is shown on the attached Figure 1.' The seal steam (gland steam evaporator steam) keeps turbine internal steam from leaking to the stack via the gland steam condenser. When the seal steam pressure is less than 11 kPaG, turbine internal steam is released to the gland steam condenser (see Figure-2).

No COLA revision is required as a result of this RAI response.

Question 10.04.03-1 ABR-AE-08000037 Attachment 4 Page 2 of 2 To To From To FWH main gland steam gland steam condenser evaporator condenser Turbine Atmosphere intTboal

(* Turbine rotor Figure-I HP turbine gland To To From To FWH main gland steam gland steam condenser evaporator condenser Turbine V A]tosphere internal Turbine rotor Figure-2 HP turbine gland (Seal Steam pressure less than 1I kPaA)

Question 10.04.03-2 ABR-AE-08000037 Attachment 5 Page 1 of 1

.Question 10.04.03-2 QUESTION:

FSAR Section 10.4.3.3, "Evaluation," describes that the turbine gland sealing system (TGSS) is designed to prevent leakage of radioactive steam from the main turbine shaft glands and valve stems. Also, FSAR Section 10.4.3.3 states, "The high-pressure turbine shaft seals must accommodate a range of turbine shell pressure from full vacuum to approximately 17.3 MPaA. The low-pressure turbine shaft seals operate against a vacuum at all times." Referring to the ABWR DCD, in the COL application the maximum operating pressure limit for the high-pressure turbine shaft seals is increased from 1.52 MPaA to 17.3 MPaA. Since GDC 60 requires controlling radioactive release to the environment, it is not clear to the NRC staff how the TGSS will be able to accommodate this increased pressure demand for the sealing steam. Therefore, the NRC staff requests the applicant to explain how the system will adequately supply the sealing steam at the 17.3 MPaA limit, and its ability to prevent radioactive releases to the environment.

RESPONSE

The expected maximum shell pressure is actually 1.77 MPaA. The COLA pressure of 17.3 MPaA is in error, and will be revised accordingly. The revised value of 1.77 MPaA is a slight increase over the value specified in the DCD of 1.52 MPaA and can easily be accommodated by the gland seal system. The second sentence in FSAR Section 10.4.3.3 will be revised as follows:

The high-pressureturbine shaft seals must accommodate a range of turbine shell pressure from full vacuum to approximately 52 4-741.77%MPaA.

Question 10.04.03-3 ABR-AE-08000037 Attachment 6 Page 1 of 3 Question 10.04.03-3 QUESTION:

In STP COL FSAR Section 10:4.3.2.1, Figure 10.4-2 is referenced as part of STD DEP 10.4-1.

FSAR Figure 10.4-2 differs from that in the ABWR DCD, with the following deletions and additions:

Deletions: 1) loop seal between the turbine building ventilation exhaust and the condensate drain tank, 2) pressure switch between the exhaust blowers and the condensate storage and transfer line, 3) vent on the condensate drain tank link to the gland steam condenser, 4) flow arrow for the condensate into the gland steam condenser, 5) "*4A, B, and C" labeling for the FWH line, and 6) adjustment of the valve lineup for auxiliary steam. Addition: a gland seal steam line that goes nowhere (found between the relief valve to the condenser and the FWH flow line). Additionally, FSAR Figure 10.4-2 does not show how the gland seal evaporator (GSE) ties in with the turbine auxiliary steam header, main steam lines ahead of the turbine main stop valves, turbine extraction, and condensate described in STD DEP 10.4-1. FSAR Figure 10.4-2 does not show the GSE relief valves that protect the tubeside and shellside from overpressure, the relief valve flow paths, and the modulating control valves. NUREG-800 Standard Review Plan (SRP) Section 10.4.3, Item 111.1 specifies that "P&IDs [piping and instrumentation diagrams]

reflect the source of sealing steam and the disposition of steam and noncondensables vented from the gland seal." Therefore, the staff requests additional information as to how these changes are incorporated into STD DEP 10.4-1, as well as a more accurate depiction of the process flow for the TGSS so that SRP Section 10.4.3, Item 111.1 can be satisfied.

RESPONSE

1) The loop seal between the turbine building ventilation exhaust and the condensate drain tank has been deleted in the Toshiba design. The blower drain line is connected to the U-seal at the bottom of the Gland Steam Condenser instead. The FSAR will be revised as shown on the attached revised Figure 10.4-2.

2) The pressure switch between the exhaust blowers and the condensate storage and transfer line is not needed in the Toshiba design. In the certified design, the standby blower starts on a pressure signal. In the Toshiba design, the standby blower is started manually.

3) The vent on the condensate drain tank line to the gland steam condenser is necessary; however, in the revised design, it is incorporated into the U seal line. The FSAR will be revised as shown on the attached revised Figure 10.4-2.

4) The flow arrow for the condensate into the gland steam condenser was removed in error. The FSAR will be revised as shown on the attached revised Figure 10.4-2. I

5) The "*4A, B, and C" labeling for the FWH line was removed in error. The FSAR will be revised as shown on the attached revised Figure 10.4-2 to reincorporate the labeling.

6) The valve depiction in COLA Revision 1 is incorrect and will be revised as shown on the attached revised Figure 10.4-2.

7) The depiction of the gland seal steam connection in COLA Revision 1 is incorrect and will be revised as shown on the attached revised Figure 10.4-2.

Question 10.04.03-3 ABR-AE-08000037 Attachment 6 Page 2 of 3

8) FSAR Figure 10.4-2 will be revised as shown on the attached revised Figure 10.4-2 to show the gland seal evaporator (GSE) ties with the turbine auxiliary steam header, the main steam lines ahead of the turbine main stop valves, turbine extraction, and condensate as described in STD DEP 10.4-1.

9) FSAR Figure 10.4-2 will be revised as shown on the attached revised Figure 10.4-2 to show the GSE relief valves that protect the tube side and shell side from overpressure, the relief valve flow paths, and the modulating control valves.

-I

GLANDSTEAMto TO COND 0

GLAND STEAM CONDENSER J0 SMAIN CONDENSER note HIGHPRESSURE LoWPRFURE LOWPRESSULWPRRUREI TURBINE TUBINE TUBI UBN No4 FW**4B,C TO*a TOMICNDSE GLAN0 STE0 Figure 10.4-2 Turbine Gland Seal System o 0