ML18024B050

Evaluation of Environ Effects on Nonsafety-Related Sys Resulting from Postulated High Energy Pipe Failures Inside & Outside Primary Containment.

ML18024B050
Person / Time
Site:	Browns Ferry
Issue date:	10/05/1979
From:	TENNESSEE VALLEY AUTHORITY
To:
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ML18024B049	List: ML18024B048 ML18024B050
References
NUDOCS 7910120148
Download: ML18024B050 (12)

Text

EVALUATION OF ENVIRONMENTAL EFFECTS ON NONSAFETY RELATED SYSTEMS RESULTING FROM POSTULATED HIGH-ENERGY PIPE FAILURES INSIDE AND OUTSIDE PRIMARY CONTAINMENT FOR BROWNS FERRY NUCLEAR PLAIT UNITS 1, 2, AND 3 OCTOBER 5, 1979

INTRODUCTION'VA has performed a systematic evaluation of the environmental effects on nonsafety-related systems resulting from postulated high-energy pipe failures inside and outside containment. Halfunctions were then evaluated for a potential effect on safety systems. Those systems relied upon to mitigate the consequences of a high-energy pipe break and those required to obtain and maintain the plant in a cold shutdown following. such a postulated event were examined and whgre applicable previous pipe break studies formed the basis for the evaluations in this report.

ANALYSIS METHOD In analyzing the potential effects of a high-energy line break on nonsafety-related systems, the following general approach was used:

(1) The location of the system was determined. Particular attention was given as to whether or not a system had portions inside or penetrating the primary containment or inside secondary containment.

(2) The system was examined to det'ermine if it had physical or electrical interfaces with components in a safety-related system.

(3) If the system:

(a) was.inside or penetrated primary containment; or, (b) was inside secondary containment; or, (c) interfaces with a component in a safety-related system, then the system was examined to determine what control functions were in the zone of influence of a high-energy line break.

(4) If the system was determined to have control functions in the zone of influence of a high-energy line break, then the potential effects of a malfunction of that control function were examined, especially with regard to affectittg safety-related systems.

(5) If a malfunction was determined to have a potentially adverse effect on a safety-related system, the environmental qualifications of the components postulated to fail were examined. The worst case environment was assumed to exist.

ANALYSIS CONTINUED In determining if a nonsafety-related system had components within the zone of influence of a high-energy line break, specific break sizes and locations were not used. Instead, bounding assumptions were used as a conservative approach. A component in the zone of influence of a break was assumed to fail for analysis purposes.. If failure led to a potentially adverse effect on plant safety, the specific conditions were used to determine if the component was qualified. Worst case conditions were assumed for qualification purposes even though a small break or critical crack could result in an adverse malfunction that would not occur with a large break. Although the adverse environment due to' small break or critical crack may not be as severe as that for a large break, in this study, it was assumed to be for conservative purposes.

In several cases, nonsafety-related system components could malfunction, giving spurious annunciations and indications in the main control room.

No cases were found where these spurious signals affected safety-related equipment. The plant operators are instructed to rely on the safety-related indications and annunciators. We do not consider spurious indications for nonsafety systems to be a plant safety hazard.

CONCLUSION In our evaluation we found no cases where a nonsafety-related system could malfunction so as to have an adverse effect on plant safety.

The conclusions and summary of TVA's evaluation are presented in Table I which follows.

Y>> YES TABLE I HATRIX FOR POTENTIAL N ~ NO CONTROL INTERACTIONS BETWEEN SAFETY AND NON-SAFETY SYSTEHS Portions Inside Primary Portions Inside Secondary Interfaces with Safety System Experiences Malfunction That Containment Related S stem ersel Comments S stem Containment Ma Ad N Effects on safety Hain Steam system previously (Steam Tunnel) analyzed N Outside zone of Extraction Steam influence Results of mal-Reactor Feedwater N function bounded by (Steam Tunnel) t)e galyses of FSAR Condensate N N Outside zone of influence N Outside zone of Heater Drains & Vents N influence Turbine Drains N N Outsade zone of influence N

Malfunction results Off-Gas System N N in loss of vacuum-analyzed in FSAR ...

14.5 - Outside zone quahBek isolation Reactor Water Clean Up valves Can be manually con-Auxiliary Boiler nected to HPCI 6 RCIC (Separated by manuaQy~

closed valves and needs spoolpicco installation Outside zone of Lubrication Oil System influence Control system is Nuclear Boiler qualified for adverse (RPV Head Vent) environment

Portions Inside Primary Portions Inside Secondary Interfaces with Safety System Experiences Malfunction that S stem Containment. Containment Related S stem Ha Adverselv Affect Plant afe v Comments Condensate Storage Has qualified isolation from safety systems Chemical Cleaning N N N N Used preopcrational only Reactor Building Closed Y Qualified isolation Cooling Water (Fuel Pool Cooling)

Breathing Air N N N Outside zone of influence Radwaste Y Qualified isolation (Conaects to drywell Y'Connects to drains (RHR) & manual normally equipment drain sump) and sumps) closed valves Condenser Circulating N Outside zone of influence Fuel Pool N Y N Valves & controls Demineralizer are outside break zone of influence Condensate . N N N Outside zone of Demineralizer influence Makeup to Water N N N N Outside zoae of Treatment influence Potable Water N N No interface with a safety system, mal-function will not affect safety related systems Raw Water Yard N See RSW & Fire Prot: See RSW & Fire Prot. Outside zone of influence Portions Inside Primary Portions Inside Secondary Interfaces with Safety System Experiences Malfunction That S stem Containment Containment Related S stem V Comments Cleanup Filter N N N Outside zone of Demineralizer influence Rav Water N N N Outside zone of Chlorination influence Fuel Oil N N Y 0+side zone of (D.G. 7-day supply) influence Gland Seal Water N N N No interfaces Mith safety related equipment - malfunc-tion cannot affect safety related equipment Insulating Oil N N N Outside zone of refluence Storage, Fire N N N N Outside zone of CO2 Prot., Purging influence Raw Cooling Water N Y N Qualified isolation (EECW) valves and check valves separate systems - no RCW failure can affect EECW operation Compressed Air Y Manually isolated (Station Service) (SLC) from SLC vith locked Compressed Air for N

'N N Malfunction cannot Condensate Demin. afflict safety system Rackvash

- No interfaces exist Portions Inside Primary Portions Inside Secondary uter aces t a ety System Experiences Halfunction That S stem Containment Containment Related S stem Adve se fe Connects Control Air includes Y N Loss of air is iso-Orywell Control Air (ADS or HSIV's, but lated from ADS 6 HSIV have accumulators) accumulators by check valves in series Vacuum Priming Y Isolatxon valve not (EECM) affected by adverse environment Hydrogen for Cen. Cooling N N N Outside zone of influence Fire Protcctin and Raw N N N Previously evaluated Service Mater spurious spray-requires operator action within I hour due to flooding Station Drains Reactor Y Y Qualified isolation Bldg. (Primary Containmcnt valves Isolation)

Secondary Chem. Feed N N N Outside zone of influence Demineralized Mater Y N Hanual isolation Distribution (SLC) valves that are normally closed Condenser Tube Cleaning N N N Outside zone of influence Containment Inerting Y N System isolated by qualified valve HVAC Y Y Qualified isolation (Drywall HVAC) (Containmcnt Isolation) valves for Secondary Containment Isolation

Portions Inside Primary Portions Inside Secondary er ac s a System Experienkes Malfunction That S stem Containment Containment Related S stem Ma Adverselv Affect Plant Sefet Comments Building Heating Y Qualified isolation (cxcept Control Bay HVAC) (Containment Isolation) valves for Secondary Containment isolation

'lectrically isolated Lighting by qualified means from safety-related equipment N

Electrically isolated, Communications by qualified means from safety related equipment Y Isolated by normally Process Sampling closed manually (Containment Isolation) operated valves Qualified for adverse Safety/Relief Valves environment (non-ADS)

Outside xone of Fuel Handling Equipment influence Electrically isolated Process Radiation Monitoring N by qualified means (Honsafety-related portions) from safety-related equipment Electrically isolated Area Radiation Monitoring N by qualified means .

from safety-related equipment Electrically isolated Normal A-C Auxiliary Power Y by qualified means from safety-related equipment Electrically isolated Auxiliary D-C Power by qualified means .

from safety-related equipment N Qualified for adverse Suppression Pool environment Temperature Monitoring Failures previously Turbine Control analyzed in FSAR Portions Insi e Primary Port ons Insi e econ ary nter aces w t a ety System Experiences Malfunction Ihat mments S stem Containmcnt Containment Related S stem Reactor Manual Control Does not interface with safety-related equipmcnt Neutron Monitoring N Does not interface (Nonsafety portions) with safety-related equipment Process Computer N Electrically isolated by qualified means from safety-related equipment Recirculation Plow N N Failures previously Control System analyted in FShR Reactor Core Isolation Qualified isolated Cooling valves J7 S~

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