ML20148H166

Forwards RAI Re Mod to Svc Water Head Tanks at Plant,Unit 2. Response to RAI Requested within 20 Days of Receipt of Ltr

ML20148H166
Person / Time
Site:	Calvert Cliffs
Issue date:	06/04/1997
From:	Dromerick A NRC (Affiliation Not Assigned)
To:	Cruse C BALTIMORE GAS & ELECTRIC CO.
References
TAC-M98093, NUDOCS 9706090261
Download: ML20148H166 (6)

Text

_ . . _ . _ _ _ = _ _ . _ _ __ _ . _ _ _ _ _ _ _ _ _ __ _ _ _ . . _ _ _ _

-. Mr. Charles H. Cruse June 4, 1997 Vice President - Nuclear Energy -'

Baltimore Gas and Electric Company.

Calvert Cliffs Nuclear Power Plant i 1650 Calvert Cliffs Parkway _

L Lusby, MD 20657-4702-

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING MODIFICATION TO SERVICE WATER HEAD TANKS AT CALVERT CLIFFS NUCLEAR POWER PLANT,  ;

UNIT NO. 2'(TAC NO. M98093) i

Dear Mr. Cruse:

i The NRC staff has completed a preliminary review of the Baltimore Gas and Electric Company's March 6,1997, request to make modifications to the service water head tanks at Calvert Cliffs Unit 2, including a review of the licensee's response to the staff's request for additional information that was submitted on March 26, 1997. However, as discussed in the enclosure, the staff has determined that additional information is required in order to ,

complete this review.

.Your response to this request for additional information is requested within 20 days of receipt of this letter. Should you have any questions, please do

-not hesitate to contact me at (301) 415-3473.

Sincerely, ORigiNM SiONED By:

Alexander W. Dromerick, Sr. Project Manager Project Directorate I-1 >

Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation -

! Docket No. 50-318 i

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Enclosure:

Request for Additional '

Information ,

j. cc w/ enc 1: See next page DISTRIByrION:

1 Docket File; A. Dromerick L. Doerflein, RI b PUBLIC S. Little PDI-l R/F OGC g

l S. Varga ACRS l

L RIRC HLE CENTER COPY DOCUMENT NAME: G:CCl-2\M98093.RAI To receive a copy of this document, indicate in the box: "C" - Copy without

' attachment / enclosure "E" - Copy with attachment / enclosure "N" - No copy OFFICE PM:PM 1 jA lE LA:PDI-1 j Q, l DiPgfy s // l DD DRPE N l l l

NAME ADr W SLittleM ADfjne M k(A) JZwolinski V l DATE 06 M /P7 06/m3 /97 06/ A /97 06/d'/97 l Offictal Record Copy

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9706090261 970604 PDR ADOCK 05000318 P PDR l

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So arouq L - $4 UNITED STATES g NUCLEAR REGULATORY COMMISSION 2 WASHINGTON, D.C. 2055H001 4

9 . , , g ,d June 4,1997 Mr. Charles H. Cruse  :

Vice President - Nuclear Energy Baltimore Gas and Electric Company Calvert Cliffs Nuclear Power Plant

.1650 Calvert Cliffs Parkway i Lusby, MD -20657-4702

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING MODIFICATION TO SERVICE WATER HEAD TANKS AT CALVERT CLIFFS NUCLEAR POWER PLANT, i UNIT N0. 2 (TAC N0. M98093) ,

Dear Mr. Cruse:

The NRC staff has completed a preliminary review of the Baltimore Gas and )

Electric Company'_s March 6,1997, request to make modifications to the service water head tanks at Calvert Cliffs Unit 2,-including a review of the licensee's response to the staff's request for additional information that was l submitted on March 26, 1997. However, as discussed in the enclosure, the

! staff has determined that additional information is required in order to complete this review. ]

Your response to this request for additional information is requested within 20 days of receipt of this letter. Should you have any questions, please do i not hesitate to contact'me at (301) 415-3473.

Sincerely, i 1

l

, & NJ A exandir W. Dromerick, Sr. Project Manager 1 l

l Project Directorate I-1 l Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-318

Enclosure:

Request for Additional Information

! cc w/ encl: See next page 1

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i 7-Mr. Charles H. Cruse Calvert Cliffs Nuclear Power Plant Baltimore Gas & Electric Company Unit Nos. I and 2  ;

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cc:

! President Mr. Joseph H. Walter, Chief Engineer Calvert County Board of Public Service Commission of Commissioners Maryland 1 175 Main Street Engineering Division l Prince Frederick, MD 20678 6 St. Paul Centre Baltimore, MD 21202-6806 James P. Bennett, Esquire Counsel Kristen A. Burger, Esquire  ;

Baltimore Gas and Electric Company Maryland People's Counsel P.O. Box 1475 6.St. Paul Centre Baltimore, MD 21203 Suite 2102 Baltimore, MD 21202-1631- ,

Jay E. Silberg, Esquire Shaw, Pittman, Potts, and Trowbridge Patricia T. Birnie, Esquire '

2300 N Street, NW Co-Director

. Washington, DC 20037 Maryland Safe Energy Coalition l P.O. Box 33111 l Mr. Thomas N. Prichett, Director Baltimore, MD 21218 ]

NRM Calvert Cliffs Nuclear Power Plant Mr. Loren F. Donate 11 1 1650 Calvert Cliffs Parkway NRC Technical Training Center Lusby, MD '20657-4702 5700 Brainerd Road Chattanooga, TN 37411-4017 Resident Inspector U.S. Nuclear Regulatory _

Commission P.O. Box 287 ,

St. Leonard, MD ~20685- l Mr. Richard I. McLean .

Administrator - Radioecology )

Department of Natural Resources j 580 Taylor Avenue 1 Tawes State Office Building, B3 i Annapolis, MD 21401 <

Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406

l..

REQUES1 FOR ADDITIONAL INFORMATION REGARDING i MODIFICATIONS TO THE SERVICE WATER HEAD TANKS AT CALVERT CLIFFS UNIT 2 The NRC staff has reviewed the licensee's response of March 26, 1997, to the staff's initial request for additional information dated March 13, 1997, and has determined that the following additional information is required in support of the licensee's request to modify the service water system head tanks at Calvert Cliffs Unit 2:

1. Discuss the relevant aspects of the design and design basis of the service water system in sufficient detail to enable the staff to understand how the system function and design basis is affected by the planned modification, and what the specific requirements are for maintaining system operability. For example:

• Describe the various modes of operation of the service water system that are allowed by the Technical Specifications (TSs) and final safety analysis report (FSAR) that do not require entry into a TS Limiting Condition for Operation Action Statement. For example, operation with one service water heat exchanger out for maintenance and the two subsystems cross-connected is referred to in note (a) of FSAR page 9.5-21.

• Discuss the required service water system response for accident conditions, and describe the worst-case situation for the Generic Letter (GL) 96-06 scenario, including (for example) initial operating conditions and system alignment, sequencing and timing of equipment (including valves) and basis for the timing sequence, and relevant parameters and assumptions. Discuss how the system  ;

response will be affected by the planned modifications. I

• Describe any system leakage restrictions necessary to assure system operability, including measures that are taken to assure that i allowed leakage rates are not exceeded. l

• Provide a simplified system diagram that identifies the various components and valves, including component identification.

2. Describe the specific design requirements and limiting assumptions for the nitrogen overpressurization system that are relied on to assure that the service water system is operable. For example:

• Explain the limiting assumptions for sizing the nitrogen accumulators (e.g., head tank level, temperature, system leak rate, etc.). Also, discuss why it is necessary to designate the nitrogen pressurization system and accumulators " safety-related."

• Describe the specific head tank pressure, level, and temperature requirements (maximum and minimum) necessary to assure system operability, including basis. (Examples: explain how 14 psig was

arrived at as minimum required pressure, including limiting assumptions; assuming that 14 psig are required in the head tanks to Enclosure

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avoid saturation in the service water system, what is the minimum.

pressure requirement assuming the maximum allowed pump degradation, l

instrument uncertainties, maximum system. leak rate, isolation times l for non-essential loads, etc.). Describe the measures that will be taken to assure that these head tank parameters are maintained in the required band.

. Explain how the head tank level and pressure alarm setpoints were .

t established.

• Describe the worst-case accident response scenario for the service

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i water system (post modification) relative to the water hammer, two- )

phase flow, and thermal overpressurization concerns expressed in j GL 50-06 (assuming single active failure, ultimate heat sink '

conditions, system leakage, etc.); discuss the minimum time available to boiling.

• Discuss the impact (if any) that the water hammer, two-phase flow, f and thermal overpressurization concerns of GL 96-06 have on the station blackout coping analysis.

• Discuss the results of the failure modes and effects analysis relative to the water hammer, two-phase flow, and thermal .

overpressurization concerns expressed in GL 96-06. Note: this .

should not be limited only to the newly installed components but l should include all component failures that can have an impact, such  !

as system valve failures, electrical failures, air system failures,  ;

failure of fans to shift speed, failure of breakers to trip, etc. '

3. Discuss the measures that are or will be taken to assure that the turbine building return check valves do not leak excessively (e.g.,

periodic testing, inspection, trending). In particular, explain what the specific program requirements are for these check valves.

4. Fer the FSAR, the service water heat exchanger is limited to 200 'F. Is this or any other temperature or design limitation exceeded as a ,

consequence of the planned modifications? Expl ain.

5. Discuss the potential for vapor binding of the service water pumps during normal operation and during accident conditions (post modification).

6. Explain what effect (if any) nitrogen saturation of the service water  !

will have on heat transfer and accident analysis assumptions.

7. Recognizing that head tank indication and alarm instrumentation is not safety-related, discuss measures that will be taken to assure that operator indications of head tank conditions are a'ccurate (e.g.,

temperature, pressure, level, alarms). t i e I

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8. Describe and justify any aspects of the proposed modification that will not conform to the design basis requirements for Calvert Cliffs Unit 2.

9. Describe'any post modification testing, periodic testing,, and periodic .

surveillances that will be credited for assuring system operability. '

10. Discuss personnel safety and operational limitations associated with head tank nitrogen leakage, and discuss measures that will be taken to assure that these limitations are not exceeded,

11. Describe any TS surveillance requirements that will be implemented to i assure continued operability of the service water system.

12. Recognizing that the service water system is a closed loop system that consists primarily of demineralized water, explain the basis for  :

assuming a 50% reduction in water hammer loads due to " dissolved gasses," including a discussion of supporting test data. Also, discuss to what extent the water hammer loads were increased (including basis for the determination) to account for system-structure interaction effects.

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