ML18024B050
| ML18024B050 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/05/1979 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML18024B049 | List: |
| 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 N ~ NO TABLE I HATRIX FOR POTENTIAL CONTROL INTERACTIONS BETWEEN SAFETY AND NON-SAFETY SYSTEHS S stem Hain Steam Extraction Steam Portions Inside Primary Portions Inside Secondary Interfaces with Safety Containment Containment Related S stem N
(Steam Tunnel)
N System Experiences Malfunction That Ma Ad ersel Comments Effects on safety system previously analyzed Outside zone of influence Reactor Feedwater Condensate N
N (Steam Tunnel)
N Results of mal-function bounded by t)e galyses of FSAR Outside zone of influence Heater Drains & Vents N
N Outside zone of influence Turbine Drains N
N Outsade zone of influence Off-Gas System Reactor Water Clean Up N
N N
Malfunction results in loss of vacuum-analyzed in FSAR...
14.5 - Outside zone quahBek isolation valves Auxiliary Boiler Lubrication Oil System Can be manually con-nected to HPCI 6 RCIC (Separated by manuaQy~
closed valves and needs spoolpicco installation Outside zone of influence Nuclear Boiler (RPV Head Vent)
Control system is qualified for adverse environment
S stem Condensate Storage Portions Inside Primary Portions Inside Secondary Interfaces with Safety System Experiences Malfunction that Containment.
Containment Related S stem Ha Adverselv Affect Plant afe v Comments Has qualified isolation from safety systems Chemical Cleaning Reactor Building Closed Cooling Water Breathing Air N
N N
N N
Y (Fuel Pool Cooling)
N N
Used preopcrational only Qualified isolation Outside zone of influence Radwaste Condenser Circulating Y
(Conaects to drywell equipment drain sump)
Y'Connects to drains and sumps)
N (RHR)
Qualified isolation
& manual normally closed valves Outside zone of influence Fuel Pool Demineralizer Condensate Demineralizer Makeup to Water Treatment N
. N N
Y N
N N
N N
N Valves & controls are outside break zone of influence Outside zone of influence Outside zoae of influence Potable Water Raw Water Yard N
N N
See RSW & Fire Prot:
See RSW & Fire Prot.
No interface with a safety system, mal-function will not affect safety related systems Outside zone of influence S stem Portions Inside Primary Portions Inside Secondary Interfaces with Safety Containment Containment Related S stem System Experiences Malfunction That V
Comments Cleanup Filter Demineralizer N
N N
Outside zone of influence Rav Water Chlorination N
N N
Outside zone of influence Fuel Oil Gland Seal Water N
N N
Y (D.G. 7-day supply)
N N
0+side zone of influence No interfaces Mith safety related equipment - malfunc-tion cannot affect safety related equipment Insulating Oil N
N N
Outside zone of refluence CO2 Storage, Fire Prot., Purging N
N N
N Outside zone of influence Raw Cooling Water N
Y (EECW)
N Qualified isolation valves and check valves separate systems - no RCW failure can affect EECW operation Compressed Air (Station Service)
Y (SLC)
Manually isolated from SLC vith locked Compressed Air for Condensate Demin.
Rackvash N
'N N
Malfunction cannot afflict safety system
- No interfaces exist S stem Portions Inside Primary Portions Inside Secondary Containment Containment uter aces t
a ety System Experiences Halfunction That Related S stem Adve se fe Connects Control Air includes Orywell Control Air Vacuum Priming Hydrogen for Cen. Cooling N
N Y
(ADS or HSIV's, but have accumulators)
Y (EECM)
N N
Loss of air is iso-lated from ADS 6 HSIV accumulators by check valves in series Isolatxon valve not affected by adverse environment Outside zone of influence Fire Protcctin and Raw Service Mater N
N N
Previously evaluated spurious spray-requires operator action within I hour due to flooding Station Drains Reactor Bldg.
Y Y
(Primary Containmcnt Isolation)
Qualified isolation valves Secondary Chem.
Feed N
N N
Outside zone of influence Demineralized Mater Distribution Y
(SLC)
N Hanual isolation valves that are normally closed Condenser Tube Cleaning N
N N
Outside zone of influence Containment Inerting HVAC Y
(Drywall HVAC)
Y N
Y (Containmcnt Isolation)
System isolated by qualified valve Qualified isolation valves for Secondary Containment Isolation
S stem Portions Inside Primary Portions Inside Secondary Containment Containment er ac s
a Related S stem System Experienkes Malfunction That Ma Adverselv Affect Plant Sefet Comments Building Heating (cxcept Control Bay HVAC)
Lighting Communications Process Sampling Safety/Relief Valves (non-ADS)
Fuel Handling Equipment N
Y (Containment Isolation)
Y (Containment Isolation)
Qualified isolation valves for Secondary Containment isolation
'lectrically isolated by qualified means from safety-related equipment Electrically isolated, by qualified means from safety related equipment Isolated by normally closed manually operated valves Qualified for adverse environment Outside xone of influence Process Radiation Monitoring (Honsafety-related portions)
Area Radiation Monitoring N
Normal A-C Auxiliary Power Y
Auxiliary D-C Power Suppression Pool Temperature Monitoring Turbine Control N N Electrically isolated by qualified means from safety-related equipment Electrically isolated by qualified means from safety-related equipment Electrically isolated by qualified means from safety-related equipment Electrically isolated by qualified means from safety-related equipment Qualified for adverse environment Failures previously analyzed in FSAR
S stem Portions Insi e Primary Port ons Insi e econ ary Containmcnt Containment nter aces w t a ety System Experiences Malfunction Ihat mments Related S stem Reactor Manual Control Does not interface with safety-related equipmcnt Neutron Monitoring (Nonsafety portions)
N Does not interface with safety-related equipment Process Computer Recirculation Plow Control System Reactor Core Isolation Cooling N
N N
Electrically isolated by qualified means from safety-related equipment Failures previously analyted in FShR Qualified isolated valves J7 S~
ll)
.I