ML20058K930

Provides Suppl Info Re Interior Flooding

ML20058K930
Person / Time
Site:	Monticello
Issue date:	08/24/1973
From:	Mayer L NORTHERN STATES POWER CO.
To:	Ziemann D US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 9104260285
Download: ML20058K930 (11)

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Mr. Dennis L Ziemann, Chief (- /

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Operating Reactors Branch #2 h[.

Directorate of Licensing United States Atomic Energy Cor:raission Y .,

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Washington, D C 20545 'yj,g;

Dear Mr. Ziemann:

MONTICELLO NUCLFM GENERt."ING PIANT Docket No. 50-263 License No. DPR-22 Supplementary Infornation on Interior Flooding ,

Pursuant to your August 3,1972 letter, we provided information regarding interior floo6 potential resulting from postulated equipt ant failures. In our response, dated September 28, 1972, we identified tuo areas wherein consideration was being given to providing modifications which would reduce the potential for adverse interactions. The modiffcations considered were the upgrading of the condensate transfer lines in the RHR-CSS pump rooms to seismic category I equivalent and the installation of flooding alarros in the condenser hotvell area. The engineering has been started to determine the scope of these modifications and a proposal is currently being evalu-ated which also includes upgrading the condensate transfer line section in the HPCI room and also the installation of flood alarms in the circu-lating water punp bay. The proposed flood probes considered for both areas will include multi-level alarms and a circulating water pump trip at the high level. The installation will be generally in accord with IEEE-279 except that all channels will converge at a common board in the control room, h do not believe that this jeopardizes proper functioning of the alarm trip system, or in any way compromises safety.

A seismic analysis of the condensate transfer lines has shown that no modifications are required to enable the secdon in the RHR-CSS pump rooms to withstand the safe shutdown earthquake (SSE). 'lowever, the section in the HPCI room will require a single horizontal restraint. The decision to in-clude th c section was not restricted to flooding considerations in that the i backup system for the HPCI is unaffected by this event end the reactor can be shat down safely withcut the HPCI. From a flooding stLndpoint, it is considered good design practice and, also, tFe upgrading would enhance the integrity of the CRD pump suction which is taken off the CST section in the HPCI room.

9104260285 730824 "

6b' CF ADOCK 05000763 CF

NORT. ;R N CTATEO POWER COh ANY

' In response to a request from AEC-Regulatory Operations, Region 111, a supplemental invesr{ ;ation was conducted to determine the ef fects of cir-culating water pump bellows failure in the circulating water pump bay. As teported previously, levels would be limited by the river water level.

Though this is ultimately true, it can be demonstrated that the river level can be exceeded for a short tbne following the event. As the IcVel increases following the event, the pump motors are flooded out before the water exceeds the operating floor level. The circulating water pump coastdown was measured to require approximately 60 seconds. It was found that the water level would exceed the operating floor level before the pump stopped. The overflow would spill into the intake structure access tunnel and cculd possibly enter the turbine building. The maximum amount of water overflowing is estimated to be approximately 4000 ft.3 Although no significant equipment damage is expected for this amount of watet, flood probes will be installed in the pump bay.

The water level in the suction bay was assumed to be 916' MSL which provides a suction head of 13' to the circulating water pumps. The level corresponds to the maximen level for closed cycle operation. It is expected that with the addition of flood probes and the pump trip, that under most suction conditions, water would not overflow the pump bay.

As we determined in our previous review, redundant trains of engineered safeguards equipment are not coincidently effected by flooding or spraying damage from postulated Class II line failures. However, multiple component failures can be postulated to result from flooding or spraying damage to emergency switchgear and motor rantrol centers. These interactions were reviewed and it has been determined that no corrective actions are required to ensure availability of core cooling. Tables 1 and 2, attached, summar-ize the results of that review. Table 1 identifies affected electrical distribution equipment along with associated safety system loads. Table 2 identifies principal Class II systems along with points of interactions with Class I equipment including that of Table 1. A comparison of loads, noted on Table 1, with effected equipment on Table 2 shows that for the postulated flooding incident, equipment losses are covered by the remaining backup components. As is generally the case, correctise actions are planned more to reduce postulated damage than to ensure adequate availability of core cooling. There is only one case identified in this review wherein concern can be raised regarding the availability of core cooling following the incident.

That is the case of the feedwater line break in the east side of the turbine building. Corrective action.

• this accident will be more appropriately addressed in the report on high energy line failures, which will follow shortly.

It is concluded that the original criteria employed in the design of Monticello provides adequate separation of redundant components of safeguards equipment to afford protection from postulated singic failures other than the feedwater line break. Although loss of off-site power was implicitly assumed in estab-lishing the availability of safeguards equipment following a flooding incident, it was not consistently applied in assessing flood potential since loss of off-site power will in most cases terminate flooding faster than operator action.

NOR1 ERN OTATEO POWER Col ANY

-3 All modifications discussed above will be completed prior to the end of the 1975 refueling outage.

i Yours very truly, f OIKo ( yy 'muj, &~

L 0 Mayer, PE Director of Nuclear Support Services 1

LOM/DWJ/br cc: B H Grier G Charnoff Minnesota Pollution Control Agency Attn. K Dzugan Attachments l

TABLE 1 AFFECIED ESSENTIAL 125 VOLT D.C. ELECTRICAL DISTRIBUTIai MCC D111 location: 911 Level West Ibrbine Building Feeder: Distribution Panel D-ll Safety System Loads: No.103, 480V Load Center Nomal No. 104, 480V Load Center Standby  !

No. 11 Diesel Generator Control Panel No. 12 Diesel Generator Control Panel No. 15 4KV Switch Gear Nomal  :

No. 16 4KV Switch Gear Standby  !

No.11 Diesel Generator Field Flashing MCC D211 Location: 931 Level West Turbine Building Feeder: Distribution Panel D-21 Safety System Loads: No. 104, 480V Load Center Nomal No. 103, 480V Load Center Standby No. 12 Diesel Generator Control Panel ,

No. 11 Diesel Generator Control Panel No. 15 4KV Switch Gear Standby No. 16 4KV Switch Gear Normal No. 12 Diesel Generator Field Flashing AFFECTED ESSENTIAL 480 VOLT ELECIRICAL A.C. DISTRIBUTIQi l MCC B33 Location: 911 Level East Turbine Building Feeder: No. 103 Icad Center Safety Systen Loads: SBLC Pump A RHR Loop A Discharge to Containment Spray MOV (2)

RHR Loop A Suction MOV RHR Loop A Suction Cross Tie MOV Core Spray Discharge Isolation MOV Core Spray Suction Isolation MOV Core Spray Test MOV  !

RHR LPCI Suction Isolation Bypass MOV RHR Heat Exchanger Bypass MOV RHR Loop A Test to Torus MOV j RHR Loop A Test to Spray MOV  !

RHR Loop A Test Isolation MOV RHR Loop B Discharge to LPCI MOV (2)

A

i TABLE 1 (cont) $

MCC B42 Location: 931 Level East Turbine Building Feeder: No.104 load Center Safety System Loads: SBLC Pump B f RHR Loop B Discharge to Containment Spray MOV RHR Heat Exchanger Bypass MOV RHR Loop B Test Isolation MOV i,

MCC B43 f Location: 931 Level East Turbine Building Feeder: No. 104 Load Center ,

Safety System Loads: RHR Loop B Suction Cross Tie MOV '

RHR Loop B Suction MOV Core Spray Discharge Isolation MOV Core Spray Suction MOV Core Spray Test MOV RHR Loop A & B Cross Tie MOV RHR Ioop B Test to Torus MOV RHR Loop B Test to Spray MOV RHR Loop B Discharge to Containment Spray MOV RHR to Reactor Head Cooling MOV HPCI Reactor Outlet Isolation MOV RHR Loop A Discharge to LPCI MOV (2)

LOAD CENTER 103 Location: 911 Level NW Turbine Building '

Feeder: 4KV Bus No.15 .

Safety System Loads: MCC B33 LOAD CENTER 104 i

Location: 931 Level NW Turbine Building Feeder: 4KV Bus No. 16 ,

Safety System Loads: MCC B43 and B42 4KV BUS NO. 15 Location: 911 Level NW Turbine Building Feeder: Nos.11, IR, lAR Transfomers or No. 11 Diesel ,

Safety System Loads: Load Center 103 1

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TABLE 1 (cont) 4KV BUS NO. 16 i

Location: 931 Level NW Turbine Building Feeder: Nos.11, IR, IAR Transfomers or No. 12 Diesel Safety System loads: Load Center 104 AFFECTED ESSENTIAL 250 VOLT D.C. ELECTRICAL DISTRIBUTION MCC D312 Iocation: 896 Level HPCI Room Reactor Building Feeder: Distribution Panel D31  !

Safety System Loads: HPCI Turbine Gland Seal Condenser Blower HPCI Gland Seal Condenser Drain Pump  :

HPCI Auxiliary Oil Pump HPCI Reactor Outlet Isolation Valve MO 2035 i HPCI Reactor Outlet Isolation Valve MD 2036 Supp Pool to HPCI Pump Isolation Valve M0 2061 Supp. Pool to HPCI Pump Isolation Valve MO 2062 HPCI Pump Suction to Condensate Tank Valve MO 2063 HPCI Pump P207 Discharge Valve MO 2067 HPCI Pump Discharge to Reactor Valve MO 2063 HPCI Pump Discharge to Condensate Tank Valve MO 2071 HPCI Pump Discharge to Condensate Tank Valve MO 2072 MCC D313 Iocation: 962 level MG Set Room Reactor Building j Feeder: Distribution Panel D31 Safety System Loads: Evacuation Alarm Siren Recire. Pump A MG Set Emergency Lube Oil Pump Recire, Pump B MG Set Emergency Lube Oil Pump Primary Steam Lines Drain MO 2374 i RHR Loop A LPCI Suction Isolation Valve MO 2030 RHR Loop A to Reactor Head Cooling valve MO 2026 Reactor Outlet to Cleanup System Valve MO 2393 .

RHR System B to Radwaste System Valve MO 2407 P

. l TABLE 2 CIASS II SYSTD4S COPUNICATION WITH ESSENTIAL EQUIPMENT

1. System: FIREbATER (FW)

Capacity: 2-1500 gpm pumps, 1 on nomal AC, 1 diesel driven, 1-50 gpm jockey pump, normal AC.

Estimated Max. Flood: 15,000 gallons (10 min operation of 1 pump)

Termination: Operator Action r

INTERACTIONS Cor rective Component Location Hazard to: Action Req.

4" FW Line N. Turb. Bldg. EL 911 MCC-Dill None Trans. Deluge Dist. Hdr. Diesel Gen. Bldg. #12 Dies. Gen. Centr. None Hose Station Recire. MG Set Rm EL 962 MCC-D313 None Hose Station HPCI Bldg. MCC-D312 None 6" W Line Intake Struct. RHRSW Pump #11 None 4" FW Line Intake Struct. RHRSW Pump #11 None  !

i

2. System: SERVICE WATER (SW) '

Capacity: 3-6000 gpm pumps, nomal AC Power Estimate Max. Flood: Indeterminant Termination: Loss of Offsite Power, or Operator Action i INTR.RACTIONS  ;

Corrective  !

Component Location Hazard to: Action Req.  !

12" SW-3 W. Turb. Bldg. EL 931 MCC D211 None ,

24" SW-1 E. Turb. Bldg. EL 931 MCC B42 & B43 None 8" Screen Wash Intake Structure RHRSW #12 6 #14 None 24" SW-1 Intake Structure RHRSW #11 & #13 None l

3. System: CONDCiSATE (CI)

Capacity: 2-7187 gpm pumps, nomal AC Power  ;

Estimated Max. Flood: 80,000 gallons w/o Loss of NAC Termination: loss of Off-Site power, or Operator Action, or System Runout '

a I INTERACTIONS I Corrective j Component Location Hazard to: Action Req. I 30"-CI-A or CI-B N. Turb. Bldg. EL 911 MCC-D111 None

]

16"-CZA or CZB N. Turb. Bldg. EL 911 MCC-Dill None 1

4. System: FEEDWATER Capacity: 2-7820 gpm pumps, normal AC Power Estimated Max. Flood: 80,000* gallons w/o loss of N-AC Temination: Loss of Off-Site Power, or Operator Action or, system runout

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TABLE 2 (cont) f INTERACTIONS Corrective  ;

Component location Hazard to: Action Req. j FW2A & FW2B East Turb. Bldg. EL 911 MCC-B33 See Note FW2A & FW2B E. Turb. Bldg. EL 931 MCC-B42 & B43 FW2A & FW2B MSL Chase HPCI l

I NOTE: Concern interfaces with high energy line break review. As MCC's are subject to sLmultaneous exposure, corrective action is required.

This is discussed in high energy line break report. .

System: REACTOR BLDG, COOLING WATER  :

5.

Capacity: 2-3000 gpm pumps-Emergency AC, 1700 gallon surge tank i Estimated Max. Flood: Closed System, not Significant Capacity Termination: Operator Action l

INTERACTIONS l 6

(No Significant Flooding Hazard)

6. System: TURBINE BLDG. COOLING WATER i

(See SERVICE WATER) i

7. System: DD11N WATER Capacity: 2-100 gpm pumps,1 on Normal AC and 1 on Emergency AC, l 50,000 gallon storage tank, external. l EstLmated Max. Flood: 3000 gallons l Termination: Operator Action INTERACTIONS (No Significant Flooding Hazard)  ;

8. System: HEATING BOILER CONDENSATE Capacity: 2-100 gpm pumps, 2-40 gpm pumps, normal AC Power-pumped from 200 gallon and a 100 gallon receiver tank to a 4" return header to deaerator tank.

Estimated Max. Flood: 300 gallons Termination: System Runout INTERACTIONS Corrective Component Location Hazard to: Action Req.

E. Turb. Bldg. EL 931 MCC-B42 & B43 None

. 4" return Header

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TABLE 2 (cont )

9. System: CONDENSER CIRCU1ATING WATER (CW)

Capacity: 2-140,000 gpm pumps, normal AC Estimated Max. Flood: 1.5 million gallons, w/o automatic trip Termination: Self flooding, loss of Off-Site Power, or Operator Action

_ INTERACTIONS Corrective Component Location Hazard to: Action Req.

Condenser Inlets Cond. Hotvell (1) MCC-D111 Installation of Flood MCC-B33 4 probes 6 pump trip on hi wtr.

CW Pump Discharge Intake Struct. (2) -

(1) Event does not preclude core cooling in that feeders and control power for only one set of redundant equipment are affected. No credit is taken for water retention <

in hotwell area.

(2) Since event probability is established, flood probes and trip will be installed to limit water to CW pimp bay with no overflow to Turbine Bldg.  !

10. System: MAKEUP WATER  ;

Capacity: 2-14,000 gpm pumps  ;

(The function of this system is to provide level control in intake bays. There are no external connections and no equipment could be affected by failure of  ;

this system.)

11. System: POTABLE WATER Capacity: 1-500 gallon and 1-1300 gallon pressurized tank Estimated Max. Flood: 1300 gallons Termination: Runout INTERACTIONS (No Significant Flooding Hazard) i

12. System: CONDENSATE TRANSFER AND STORAGE SYSTEM Capacity: 2-800 gpm pumps, 460,000 Eallon storage capacity ,

Estimated Max. Flood: 460,000 gallons Termination: Operator Action INTERACTICNS Corrective  !

Component Location Hazard to: . Action Req.

ECCS Suction Supply Reactor BldR Basement

" Upgrade line C11-20 " RHR-CSSA

}J sections to i

l

& C12-12 " RHR-CSSB 4 C16-14 " HPCI Class 1 Seismic C18- 4 " HPCI

- . l TAB 12 2 (cont)

13. System: DRAINS It is felt that drains are outside of the scope of the proposed criteria in that multiple failure would be required before significant flooding hazards could be postulated from drains. And, even in that case, both the drain and the line would have to be in a comon area and the line  !

vould have to have sufficient capacity to constitute a flooding hazard on its own.

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AEC DIS

• BUTION FOR PART 50 DOCKET MATE' .L

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(TEMPORARY FORM) CONTROL NO: 6542 FILE:

A A . OMER

$ rthern States Power Company Minneapolis, Minnesota 55401 L. O. Mayer 8-24-73 8-27-73 X , {

TO:

ORIG CC lOTHER SENT AEC PDR X l X i l SENT LOCAL PDR Mr. Ziemann I signed I CLASS UNCLASS PROP INFO INPUT NO CYS REC'D DOCKET NO:

XX 40 50-263 DESCRIPTION: ENCLOSURES:

Ltr re our 8-3-73 ltr. . .. . furnishing info re flood potential resulting from postulated equipment Failures......"W/ Attached Tables 1 & 2' ACH0 WEDGED lEHot Remove --

PLANT NAME: Monticello FOR ACTION /INFORMATION 8-28-73 AB BUTLER (L) SC15JENCER(L) V ZIEMANN(L) REGAN(E)

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