ML17252A704

Forwards Final Evaluation of SEP Topic VI-10.B, Shared Sys for Multiple Unit Stations. Evaluation Will Provide Basic Input to Integrated Safety Assessment for Facility

ML17252A704
Person / Time
Site:	Dresden
Issue date:	06/20/1981
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:	Abel J COMMONWEALTH EDISON CO.
References
LSO5-81-06-074, LSO5-81-6-74, NUDOCS 8106290452
Download: ML17252A704 (11)

Text

Docket No. 50-237/10 LSOS-81-06-074 Mr. J. S. Abel e

9 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 June 20, 1981 Director of Nuclear Licensing Commonwealth Edison Company Post Office Box 767 u,s, KJCUA11 tEGUlATOft

... j COMMliSIOM

/-...

Chicago, Illinois 60690

SUBJECT:

SEP TOPIC VI-10.B, SHARED SYSTEMS FOR MULTIPLE UNIT STATIONS, DRESDEN 1 AND 2 Enclosed is a final copy of our evaluation of SEP Topic Vi-10.B, Shared Sys-terns for Multiple Unit Stations. This report has been *revised to

• .reflect the comments provided by your letter of May 2, 1979 and current format for topic evaluations.

This evaluation will be a bisic input to th~ integrated safety assessment for your facility unless you identify changes needed to reflect the as-built conditions at your facility.

This topic assessment may be revised in the future if your facility design is_ changed, if NRC criteria relating to this topic are modified before the integrated assessment is completed or pending certain findings as outlined in our evaluation.

Enclosure:

As stated cc w/enclosure:

See next page Sincerely, Llt1LJ~**

Dennis M. Crutchfield, Chi Operating Reactors Branch o. 5 Division of Licensing 5£0.f.

~ 1/1

-J)su. us4 1=')(lf.)

9

Mr. J

• S. Abe 1 cc Isham, Lincoln & Beale Counselors at Law One First National Plaza, 42nd Floor Chicago, Illinois 60603 Mr. B. B. Stephenson Plant Superintendent Dresden Nuclear Power Station Rural Route #1 Morris, Illinois 60450 Natural Resources Defense Council 917 15th Street, N. w.

Washington, D. c.

20005

u. s. Nuclear Regulatory Commission Resident Inspectors Office Dresden Stat ion RR #1 Morris, Illinois 60450.

Mary Jo Murray Assistant Attorney General*

Envi~onmental Control Division 188 w. Randolph Street Suite 2315 Chicago, Illinois 60601 Morris Public Library 604.Liberty Street Morris, Illinois 60451 Chairman Board of Supe~visors of Grundy County Gru11dy County Courthouse Morris, Illinois 60450*

John F *. Wolfe, Esquire 3409 Shepherd Street Chevy Chase, Maryland 20015 Dr. Linda w. Little 500 Hermitage Ori ve Raleigh, North Carolina 27612 Illinois Department of Nuclear Safety 1035 Outer Park Drive, 5th Floor Springfield, Illinois 62704

u. S. Environmental Protection Agency Federal Activities Branch Region V Office ATTN:

EIS COORDINATOR 230 South Dearborn Street Chicago, Illinois 60604 Dr. Forrest J. Remick 304-East Hamilton Avenue Chicago~ Illinois. 60604.

SEP REVIEW OF SHARED ENGINEERED SAFETY FEATURES, ONSITE EMERGENCY POWER, AND SERVICE SYSTEMS FOR MULTIPLE UNIT STATIONS*

TOPIC VI-10.B

• This evaluation deals only with non-EI&C equipment and structures and should be combined with the EI&C review of this topic when it is comp.l eted.

• ~*

'-***--* *-*-**-*-*. ---~--....... ----*--..---....... --- **--. --

I.

INTRODUCTION The safety objective of Topic VI-10.B is to assure that:

(1) the interconn~ction of ESF, on-site emergency power, and service systems between *different units a~e not such that a failure, maintenance or testing operation in one unit will affect the accomplishment of th~

protection function of the system(s) in other units, (2) the required coordination beb1een unit operators can cope with an incident in one unit and accomplish safe shutdown of the remaining unit(s), and (3) system overload conditions will not arise as a consequence of an acci-dent in one unit coincident with a spurious accident signal or any other single failute in another unit. This objective. appli~s only to safety related equipment and structures.

II.

REVIEW CRITERIA The sharing of structures, systems and components important to safety*

• for a multiple unit facility can result in a reduction of the number and of the capacity of on-site systems to below**that which -normally is provided for the same number of units 16cated at separate sites.

NRC Genera 1 Design Criteria 5, "Sharing of structures, systems and components,".

was developed to ensure that sharing of structures, systems and components

. important to safety among nuclear pciwer units will not significantly impair their ability to perform their safety functions, including, in the event of an accident in one unit, orderly shutdown and cooldown Qf the re~aining units.

III.

RELATED SAFETY TOPICS AND INTERFACES The scope of review for this topic was limited to avoid duplication of effort s i nee some aspects of the review have been or wi.11 be perfprmed.

under related topics.

The related topics and the subject matter are identified below.

• Each of the related topic reports contains the acceptance criteria and review guidance for its subject matter.

• UI-1

• r II-2

-..II 1.:.3~ A III-4.A III-4.B III-4.C III-12 Classification of Structures, Components and Systems (Seisr:nic and Quality).

Wind and Tornado Loadings.

Effects of High Water Level on Str~ctuies Tornado Missiles Turbine Missiles Internally Generated Missiles Environmental Qualification of Safety Related Equipment

VI-4 IX-3 IX-5 i

IX-6 Containment Isolation Systems Station Service and Cooling Water Systems Ventilation Systems Fire Protection NUREG-0737 Item III.D.3.4 Control Room Habitability IV.

EVALUATION This evaluation addresses only the non-Electrical, Instrumentation and Control (EI&C) portions of' this topic, i.~.* fluid systems and.components and structures.

The staff has identified the following structures, systems and components as being shared or capable of being cross-connected between units at Dresden Station:

1.

Service.Water System (Units 2 and 3)

2.

Fire Protection Water System (Units l; 2 and 3)

3.

Condensate Storage (Units 1, 2 and 3)

4.

Diesel Generator Mechanical Auxiliaries (Units.2 and 3)

5.

Instrument and Service Air Systems (Units l, 2 and 3)

6.

Control Room (Units l, 2 and 3)

7.

Ventilation and Air Conditioning (Units 2 and 3)

8. *Reactor Building Closed Cooling ~ater (Units 2 and 3)

9.

Crib House Structure (Units 2 and 3)

10. Standby Gas Treatment Sys tern (Uni ts 2 and 3)

11. Radwaste Building and System (Units 2 and 3)

12. Cardox Ctiz ~ire Protectiori System (Units 2 and 3)

13. Process Sa~pling System (Units 2 and 3)

• 14; Makeup Wat~r System (Units l, 2 and 3)

These systems are discussed below.

Service Water System

• .Unit T has an independent service water system (SWS). *Units 2 and 3 share one common SWS which. provides cooling. water to components and systems. (.such as the control room chillers) which may be essential for the plant's safe shutdown during normal and emerg~ncy operating con-ditions.

In addition, the SWS is used to fornish water t.o the station fire protection system and to the Diesel Generator Cooling Water Syst~m.

'*.r *,

The SWS consists of five pumps, three strainers and a common distribution header.

Normal operation requires biO pumps and one strafoer for each unit with one pump and one strainer serving as standby componerits for both units.

The pumps are located in the crib house and take their suction from the common intake structure for Units. 2 and 3.

The dis-charge fro~ any four of the five service water pumps passes through two of any of the three strainers to a common header which distributes

\\'1ate'r to various systems for both Units 2 and 3.

The common discharge header renders the system susceptible to a passive failure which would disable the entire system.

The significance of this failure, as well a~ other postulated. SWS failures will be determined in the SEP review of Topic IX-3, "Station Service and Cooling Water* Systems. This information is necessary for completion of our evaluation of the SWS for Topic VI-10.B.

Therefore, final resolution of this issue is pending the completion of. Topic IX-3.

Fire Protection Water System A description and !valuation of the Fire Pr6tection Water System is contained in ~n NRC letter dated March 22, 1978 (G. Lear to C. Reed) transmitting Operating License Amendment Nos. 25, 26, and 33 for Dresden Units 1, 2 and 3 respectively.

I~ addition to the fire fighting function, the system must supply makeup water to the secondary si~e of1}he isolation condenser for safe shutdown and cooldoWn of Unit 2.-.

The postulated accident, for which the fire protection systems may be required to function, is a fire in one of the three units.

The topic sa.fety objective (Item 3) assumes a single failure (active failure) in the system at some time after the fire starts.

The largest quantity of water flow required for fire fighting is approximately 2700 gpm based on the flow of the largest automatic sprinkler demand (19~0 gpm) plus

\\

750 gpm additional for fire hose flow. i!f the isolation condenser is to be used for shutdown and cooldown of Unit 2, the required makeup flow to the condenser i2*1375 gpm commencing approximately 20 minutes

• after r.eactor shutdown.- \\The present pumping capacity is supplied

. 'by the Unit 1.diesel pump (2500 gpm), the Unit 2/3. diesel. pump. (2000 gpm),

• *a~di.'.:!:~.~*-Se.rvice Wa.ter System pumps (15,000 gpm each).

The fire water.

flow is sufficient to fulfill the fire demand and isolation condenser mak~up if the S~rvice Water pumps are used.

These 3

~an be powered from either.offsite or onsite ~lectrical power sources.-

JI See* the SEP Review of Safe Shutdown Systems for Dresden. 2.

fl Based on proposed ANS Standard 5.1 (1973) for decay heat calculation.

y It should be noted here that other means, which do not require the fire protectiori water system, are available to shutdown and cooldown the Dresden Z facility. These are identified in the SEP Review of*

Safe* Shutdown Systems.

)

) Based on this evaluation, we conclude that the sharing of the Fire Protection Water-System meets the safety-objective of Topic VI-10.8 and is in conformarice with GDC 5.

Condensate Storage Tanks (Units 1, 2 and 3)

The Conden~ate Storage Tanks (CST) for Dresden Station are three*

tanks (contaminated: CST 2/3A and 2/3B and the Unit 1.contaminated demineralized water tank, T-105A).

CST 2/38 supplies water to the High Pressure Coolant Injection (HPCI) systems for both Units 2 and

3.

If necessary, CST 2/3A could be 1 ined up manually to supp.ly the HPCI systems.

Each of these tanks is designed to main.tain a minimum of 90,000 gal. of condensate for HPCI use.

All three tanks are capable of being cross-:connected.

CST 2/3A and 2/38 are normally connected.

Based on our review of the Unit 2 and 3 CST and Unit 1 contaminated demineralized water storage arrangements, we have concluded that the*

condensate storage design meets the safety Dbjective of Topic VI-10.B.

Diesel Generator Mechanical Auxiliaries The Diesel Generator Mechanical Auxiliaries are the cooling water, fuel.

transfer and air start systems.

The Diesel Generator Cooling Hater System consists of three pumps* in.the c~ib house - one for th~ Unit 2 diesel, one for the Unit 3 die~el and one for the shared Unit 2/3 diesel.

These pumps can be cross,-connected so that each pump can supply any of the other pumps' cooling loads, except for the diesel generatorst The pumps are normally isolated fbom each othe~ and operated as separate subsystems.

Thus a failure in one.

subsystem.would not affect the safety function of the other cooling water subsystems.

For additional reliability, the Service Hater System can.be used to supply any or all of the subsystems cooling loads.

The Diesel Oil Transfer Systems and the Air Start -Systems are separate systems for each diesel and are not.shared.

The Unit 3 Diesel Oil Transfer System also supplies the Unit 2/3 diesel fire pump.

However,.

,, the Technical Specifications for Units 2 and 3 (Section 4.12) require the fire pump diesel engine fuel day tank to contain sufficient fuel for 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> of fire pump operation. This is considered to be sufficient for any postulated fire fighting needs, Therefore, no safety concern_s arise because of the potential demand on the quantity of *stored fuel during simultaneous operation of the fire pump and the Unit 3 diesel generator. The Dresden 2 and 3 Technical Specifications (3.9.0)

• requfres a minimum of 10,000 gallons of diesel fuel supply to be kept on si~e for each diesel genefator.

/

The diesel generators are each housed in separate structures such that the failur~ of one.structu~e will not result in the failure of more than one diesel *generator.

Based on the above discussion, we conclude that the diesel mechanical au~iliaries do not constitute ~hared systems and that these systems meet the safety objective of Topic VI-10.B.

Instrument and Service Air Systems (Units 1, 2 and 3)

The Unit 2 and 3 Instrument'and Service Air Systems are shared between ihese units.

The Unit 1 Service Air System is not normally cross tied to the Unit 2/3 Service Air System.

The Unit 1 Instrument Air System is capable of being cross-connected to the Unit 2/3 In~trument Aii System, but these systems are normally isolated from each other.

None of the safe shutdown systems for Units 1 or 2 require air system~

for their operation.

The safe shutdown systems for Unit 3 were not evaluated in the SEP.

Therefore, the systeITT is not considered to be important to safety and does not need.to be evaluated under Topic VI-10.B.

I Cohtrol ~oom (Units 1, 2 arid 3)

The control room for Dresden Units l~ 2 and 3 is a common structure whi~h is inte~nally subdivided into control areas for each unit.

Besides the structure 0*itself, the control room shares a common 1

ventilating and air conditioning system (discussed below).

This evalua-tion is to determine if *sharing of the control room significantly impairs the ability to perform its safety functions..

I In order to conclude on the acceptability of this arrangement, two issues must be resolved*; _survival of the enclosing structure and habitability of i~s contained ~tmosphere. Structure survival is address~d by a number of SEP topics (as listed in Section III), and habitability is a TMI issue (see NUREG-0737, JII.D.3.4). Pending acceptable findings on both items, we have coricluded th~t the shared control room meets the safety objecti~e of Topic VI-10.B and is in conformance with General De~ign Criteria

. (GDC) 5..

Ventilation and Air Conditioning Systems (Units 2 and 3)

The Ventilation and Air Conditioning (VAC) system for the.control room for Units 1, 2 and 3. is a shared system because the-control room structure is common to all three units. Other shared portions of the VAC system are the Radwaste Building Ventilation and Ventilati~n Pressure Control for the Reactor Buildings for Units 2.and 3.

VAC ~ystems for Dresden Station will be reviewed under SEP Topic IX-5, "Ventilation Systems."

Th~ findings of Topic IX-5 are necessary for inp~t for the Topic VI-10.&*eval~ation of the VAC system.

Therefore, fin~l resolution of this issue is pending the completion of Topic IX-5.

i I

- Reactor Buildin-g Closed Cooling Water System (Units 2 and 3)

The Reactor Building Closed Cooling Water System (RBCCWS) provides cooling water to components and systems in the reactor buildirg.

The RBCCWS atts as an intermediate heat sink for the components and receives its codling water from the SWS.

Each unit has its independent RBCCWS;.there is no interaction between the RBCCWS for Unit l and the RBCCWS for Unit 2 or Unit 3.

However, there are cross-ties between the RBCCHS for Unit 2 and the RBCCWS for Unit 3.

- The system for Unit 2 or.Unit 3 is a closed loop system consisting of two 50 percent capacity pumps and two50 percent capacity heat exchangers.

In addition, a third 50. percent capacity pump and.a third 50 percent capacity heat exchanger, shared by Uriit 2 and Unit 3, will serve as standby components to provide redundan~y. Connections havi.

been provided such that the standby pump or heat exchanger can be aligned to supply cooling water to ~ither unit.

All connections between unit RBCCWS are via normally shut and locke3 manual:valves; and, therefore, they are not operated as shared systems.

We have concluded that the RBCCWS for Units 2 and 3 meet the safety objective of Topic v1~1ci.B and are in conformance with GDC 5.

The Closed Cooling ~~ater Systems at Dresden Station v1ill be further:

reviev-1ed under.SEP Tqpic IX-3, "Stat.ion Service and Cooling Water.

Systems.

11 Crib House Structure (Units 2 and 3)

The Unit 2/3 Crib House.contains portions of several systems which are i~portant to safety.

Th~se systems are Die~el Generator Cooling Water, Diesel Fire Pump,

~nd Service Water.

This structure will be evaluated during the review of SEP structural related topics and design basis events.

Pending acceptable findings from these related topics, we

~onclude that the objectives of Topic VI-10.B meet.

Standby Gas Treatment, System.,,,._.. ;,<;>**"'...

One standby gas treatment system (SGTS}, shared by Unit 2 gnd Unit 3, is provided to maintain a small negative pressure in the reactor building bf either unit following a LOCA.

Leakage from the primary containment*

into ~he reactor building will be collected and filtered by the SGTS

• prior to its release to the environment.

\\.

er,

... '\\

The SGTS. consists_ of two 100 percent capacity fan and filter trains.,....

\\

Valves and piping have been provided such that following a LOCA in a specific unit, the system will be aligned to colledt and filter the leakage into the reactor building f9r that unit.

Based on the low probability of a tOCA event in one unit coupled with the probability that a second LOCA would take place in the remaining unit, we conc)ude that the sharing of the: SGTS between.Unit 2 and Unit 3 meets the intent of the GDC 5 and the safety objective of Topic VI-10.B.

• Radwaste Building and Systems The Radfoactive. Waste Control Systems (Ra.dwaste Systems) are designed to collect, process, control, and dispose of potentially radioactivie waste in a safe manner without limiting unit or station operations or availability.

Gaseous, liquid and solid wastes are processed by the Radwaste Systems.

The shared equipment associated with the gaseous radwaste system are the Unit 2/3.effll.ent stack and the Offgas Building -for Units 2' and

3.

The entire liquid radwaste system and the Radwaste Building are shared between Units 2/3.

Also the Maximum Recycle Radwaste Sy"stem and Building are shared between U~its 2/3.

Solid waste is processed within the shared Unit 2/3 Radwaste*Buildihg and the shared Unit 2!3 Orum Stor.age Building.

Unit 1 does not.share any radwaste facilities with Uni*ts 2 and 3.

Based on our evaluation and the continuing operation of the units within their technical specification limits for radioactive effluents, we have determined that the sharing of radwaste systems at Dresden Units 2/3.

does not impair th~ ability of th~ system~ to p~rform their functions and also that the* radwaste systems are not required to perfonn any functions necessary for the safe shutdown and cooldown of Dresden Units 2 and 3.

Therefore, these systems meet the safety objective of Topic YI-10~~ and are in conformance with GDC 5. *

. Cardox C02 Fire Protection System (Units 2 and 3}

• • {...

A COz fire fighting system for Units 2 and 3 is supplied by the generator purging co2 storage unit to the three diesel generator rooms.. This system is not needed for safe shutdown of a unit in the event of an accident in the oth~r unit.

The C02 system has been evaluated from the standpoint of fire protection and the results are contained in the NRC

-lett~r of March 22, 1978 previously mentioned abqve in the Fire Protection

, Water System discussion.

Based on this previous eval~ation we conclude

'that this system meets the safety o.bjective of Topic VI-10.B and is in conformance with GDC 5.

)

.i

(.

'J.Process Sampling System (Units 2 and 3)

Except for portions of the system which perform a containme~t function, this system is not important to safety and does not need to be evaluated under this topic.

Those portions which perform a containment isolation function will be evaluated as part of Topic VI-4, "Containment Isolation Sys.terns.

11 '-'.

Makeup Water System (Units 1, 2 and 3)

( v

)

This system provides makeup water from two tanks at Unit 1 (T-105B and T-108), via a deminefali~ation system to all three units fat various purposes requiring demineralized water with no radioactive contamination.

See the Uni_t 2/3 FSAR Section 10.12 for a system descriptibn.. The system supplies water on demand and is not required to function for any' safety related purpose.

Therefore, the system is not considered to be important to safety and does not ~eed to be evaluated under Topic VI-10.B.

v. I CONCLUSION Based on o~r review of the non~Electrical, Instrumentat~on and Control portions of this topi~, we have concluded that the following shared structuresi systems and components are in coriformance with GDC 5:

1.

Fi re Protection Sys tern

2.

Condensate Storage *

3.

Diesel Generator Mechanical Auxiliaries

4.

Control Room.

5..

Reactor Building Closed Cooling Water

6.

Standby Gas Treatment System

7.

Radwaste Building and System

8.

Cardox. C02 Fire Protection System.

9.

Crib House

)

\\,

The following structures and systems were not considered to be important to safety and therefore, were not reviewed under Topic VI-1.0.B:

• 1.

Instrume'nt and Service Air Sys terns *

2. 1 Process Sampling System

3.

• Makeup Water System The Service Water System arid the Ventilation and Air Conditioning

. portions of this topic will be completed pending acceptable findings on related topics.

. (