ML20091M564

Forwards Requested Addl Info to Complete Review of Responses to Questions Re Control Sys Failure Evaluation Analyses & Info to Close SER Open Item 13

ML20091M564
Person / Time
Site:	Limerick
Issue date:	06/05/1984
From:	Kemper J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Schwencer A Office of Nuclear Reactor Regulation
References
NUDOCS 8406110344
Download: ML20091M564 (8)

Text

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PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET P.O. BOX 8699 PHILADELPHIA. PA.19101 JUN 0 51984 JOHN S. KEMPER vaCE PRE $1 DENT acessmaa nene Asso massances Mr. A.

Schwencer, Chief Docket Nos.:

50-352 Licensing Branch No. 2 50-353 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C.

20555

Subject:

Limerick Generating Station, Units 1&2 Control Systems Failures

Reference:

Letter from A. Schwencer to E. G. Bauer, Jr.

dated February 1, 1984.

File:

GOVT 1-1 (NRC)

Dear Mr. Schwencer:

Your reference letter requested additional information to complete the review of our responses to questions 421.10 and 421.11.

Attached are the responses to the questions transmitted by the reference letter.

The attachment to this letter completes our submittal of information necessary to satisfactorily close open item thirteen of the Limerick SER.

Sincerely, JLP/gra/0515841015 cc:

See Attached Service List t

940611034484060g2 -

gl PDR ADOCK 050003 E

PDR g

w.

L cc: -Judge Lawrence.Brenner (w/ enclosure)

-Jud<p Richard F. Cole (w/ enclosure)

(w/ enclosure)

Troy B. Conner, Jr., Esq.

' (w/ enclosure)

Ann P.' Hodgdon, Esq.

Mr. Frank R. Panano (w/ enclosure)

Mr. Bobert L. Anthony (w/ enclosure)

Charles W. Elliot, Esq.-

(w/ enclosure)

Zori G. Ferkin, Esq.

(w/ enclosure)

Mr. 'Ihtsnas Gerusky (w/ enclosure)

Director, Penna. Dnergency (w/ enclosure)

Management Agency Angus R. IcVe, Esq.

(w/ enclosure)

David hersan, Esq.

(w/ enclosure)

Bobert J. Sugarman, Esq.

(w/ enclosure)

Spence W. Perry, Esq.

(w/ enclosure)

Jay M. Gutierrez, Esq.

(w/ enclosure)

Atomic-Safety & Licensing (w/ enclosure)

Appeal Board Atanic Safety & Licensing (w/ enclosure)

Board Panel Docket & Service Section (w/ enclosure)

Martha W. Bush, Esq.

(w/ enclosure)

Mr. James Wiggins (w/ enclosure)

Mr. Thnothy R. ' S. Canpbell (w/ enclosure)

Ms. Phyllis Zitzer (w/cnclosure)

Judge Peter A. Morris (w/ enclosure) i I

9 m.

m.

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RESPONSES TO REQUESTS FOR ADDITIONAL INFORMATION ON LIMERICK CONTROL SYSTEM FAILURE EVALUATION ANALYSES 1.

Appendix 8 of the " Control Systems Failures Evaluation Report" provides the criteria for elimination of systems and components from the control systems failure analysis.

Regarding these criteria:

(a) Criterion N6 eliminates systems not used during normal power operations.

Start-up, shutdown and refueling systems are not evaluated.

It is the staff's concern that control system failures during plant evolutions where water level, pressure or reactivity are changing in response to turbine load or an operator's command may be of greater consequence than failures at steady state conditions.

Therefore, the evaluation should be revised, or additional justification provided to support this criterion.

(a) RESPONSE:

The methodology employed in the Control Systems Failures Evaluation is directed towards analyzing the automatic transient response of the plant during normal power operations.

The startup, shuidown and refueling modes, in general, pose a less threatening condition than normal power operations.

To further address this question, in the case of the Limerick Generating Station note that the application of Criterion N6 resulted in the exclusion of fourteen (14) systems.* Five (5) of these systems (Olesel Oil Storage and Transfer, Fuel Oil Storage and Transfer, Auxiliary Boiler,.iuxiliary Steam, and Refueling Interlock) were also eliminated by Criterion N5.

Three (3) other systems (RHR Service Water Radiation Monitoring, Primary Containment Post LOCA Radiation Monitoring and Post Accident Sampilng) were also eliminated under Criterion N2.

Two (2) systems (Olesel Generator and Diesel Generator Enclosure Ventilation) were also eliminated under Criterion N8.

One (1) system (MSIV LCS) was miso excluded under both Criterion N5 and l

Criterion N6.

The remaining three (3) systems (Coe.bustible Gas l

Control, Fire Protection and Suppression, and Remote Shutdown) are not used in normal startup, shutdown, and/or refueling operations.

Note also that the Remote Shutdown System is powered by a 1E source.

• Complete System Elimination List Attached.

Page 1 of 6 I

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k (b) Criterion N2 eliminates operator actions as a result of Indica-tions.

It is the staff's concern that operator response to erroneous indication could exacerbate the control system failure.

Therefore, the evaluation should be revised or additional justification provided to support this criterion.

l (b) RESPONSE:

The methodology of Control Systems Failure Analysis deals with electrical failure only, and as such, does not model operator actior.s.

This approach is consistent with the original questions (421.10 and 421.11) leading to the Analysis.

Electrical failures within systems provide indications to an operator, but the resultant operator action is not part of the analysis.

Operator error is, however, considered in the events analyzed in the FSAR Chapter 15.

(c) Criterion N5 eliminates systems or components which cannot affect reactor parameters within 30 minutes of the loss.

It is I

the staf f's concern that the 30 minute criterion may not allow sufficient time to detect a failure and either restore the failed components,to opJrable status or place the reactor in safe condition.

Therefore, the evaluation should be revised or additional justification provided to support this criterion.

(c) RESPONSE:

The FSAR/ Licensing criteria for operator response is that no action is credited as mitigating the event until 10 minutes l

past event initiation.

All the major reactor parameters are i

monitored and alarmed for all systems, including the contrn1 systems, so that appropriate steps can be taken to detect a failure and place the reactor in a safe condition.

Using a 30 minute time frame is then conservative and with control room Indication of the power loss, should provide more than sufficient time to restore the failed component to an operable status or to begin placing the reactor in a safe condition.

(d) Criterion N8 eliminates safety systems except for their response i

to conditions brought about by control systems failures.

The l

evaluation should be revised to include a confirmation that l

where a safety system response was required one additional random, non-mechanistic failure was considered within the responding safety system.

(d) RESPONSE:

The original question (421.10 and 421.11) did not include a requirement for the assumption of one additional random failure.

However, all events considered here are bounded by Chapter 15 analyses which consider the effects of additional single failures or operator errors.

In addition, assuming an additional failure beyond the initiating event would change the frequency classi-fication from a transient event to an accident event.

Accident Page 2 of 6 m.

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4 events are less frequent than transient events and therefore, less restrictive limits would be applied to the results of the analysis.

2.

Although the criteria for elimination of systems and components from the " Common Sensor Evaluation Report" has not been provided, it appears from statements contained in Section 3.1 of the Report that the criteria from the " Control Systems Failure Evaluation Report" were used.

Provide the criteria used for the " Common Sensor Evaluation Report" to eliminate systems and components from the evaluation.

If this criteria is the same criteria used for the " Control Systems Failure Report" address those concerns identified in Question 1 above.

2.

RESPONSE

The same criteria for the elimination of systems and components was used for the " Common Sensor Evaluation Report" as for the " Control Systems Failure Evaluation Report." The responses to Question 1 apply equally to both reports.

3.

The NRC Staff's question on instrument sensing line failures (421.11) requested confirmation that a single failure in a common instrument line or tap would not defeat required protection system redundancy.

Section 4.0 of the " Common Sensor Failure Evaluation Report" which includes a summary of the results of the study does not address this concern.

From a review of Table 4.1 it appears that certain failures can disable redundant engineered safety feature functions (e.g.,

instrument line #3 - manual initiation of MSIV leakage control inoperable).

It is the staff's concern that a single failure such as a plugged instrument tap could result in failures of multiple instrument channels.

Such failures in combination with a design basis event may not be bounded by a Design Basis Event, therefore, evaluation should be revised to address the above stated concerns.

3.

RESPONSE

Section 2.0, which provides the generalized conclusions of the report, states that a single failure in a common instrument line would not defeat the required protection system redundancy.

Section 4.0 details the interaction of consequences arising from the analysis.

The example iterated in the question.is not an exception since in each case listed, there is a loss of 1-out-of-2 only (one is a back-up to the loss of the other).

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MPL SYSTEMS REASON VI.

LEAK DETECTION SYSTEMS I

M25 MAIN STEAM LINE LEAK DETECTION l

M25 RCIC SYSTEM LEAK DETECTION l

M25 RWCU SYSTEM LEAK DETECTION l

M25 HPCI SYSTEM LEAK DETCTION l

M43 RECIRC. PUMP SEAL LEAK DETECTION l

M25 RHR SYSTEM LEAK DETECTION l

M61 DRYWELL LEAK DETECTION N2 M61 SAFETY / RELIEF VALVE LEAK DETECTION l

N2 M41 REACTOR VESSEL HEAD LEAK DETECTION l

M52 CORE SPRAY SYSTEM LEAK DETECTION l

l l

VII.

RADIATION MONITORING SYSTEMS AREA RADIATION MONITORING l

M26 SOUTH STACK EFFLUENT RADIATION MONITORING l

NORTH STACK d

MAIN STEAM LINE RADIATION MONITORING REACTOR ENCLOSURE VENT. EXHAUST REFUELING FLOOR VENT. EXHAUST RAD. MONITORING l

CONTROL ROOM VENT. RADIATION MONITORING l

CONTROL ROOM EMERGENCY FRESH AIR l

PRIMARY CONTAINMENT POST-LOCA RAD. MONITORING l

N6/N2 RHR SERVICE WATER RADITION MONITORING l

N6/N2 STAND-BY GAS TREATMENT SYSTEM l

CHARCOAL OFF-GAS TREATMENT VENTILATION l

CHARCOAL OFF-GAS TREATMENT EFFLUENT l

RECOMBINER COMPARTMENT H

/0 ANALYZER l

2 2

STEAM SEAL EFFLUENT RADIATIOM MONITORING l

RADWASTE ENCLOSURE VENT. EXHAUST l

AIR EJECTOR OFF-GAS EFFLUENT l

PRIMARY CONTAINMENT LEAK DETECTION l

HOT MAINTENANCE SHOP VENT. EXHAUST l

N3 LIQUID RADWAST DISCHARGE l

M26 SERVICE WATFR RADIATION MONITORING l

l l

VIII.

RADWASTE SYSTEM i

M69,70 GASEOUS RADWASTE l

N3 M61,62, LIQUID RADWASTE l

N3 63,64 l

M66,67 SOLID RADWASTE l

N3 1-0402 5/3/84

.MPL S_YSTEMS REASON III.

AUXILIARY SYSTEMS I

M20 DIESEL GENERATOR l

N6/N8 M20 DIESEL OIL STORAGE & TRANSFER l

N5/N6 M20 FUEL OIL STORAGE & TRANSFER l

N5/N6 M20 AUXILIARY BOILER l

N5/N6 M21 AUXILIARY STEAM l

N5/N6 NON-CLASS 1E BATTERY l

CLASS 1E BATTERY M22 FIRE PROTECTION & SUPPRESSION N6

-M15 COMPRESSED AIR SYSTEM l

l M24 CHLORINATION SYSTEM l

N5 M68 PLANT WASTE WATER EFFLUENT l

N3 M13 REACTOR ENCLOSURE COOLING WATER l

4 M14 TURBINE ENCLOSURE COOLING WATER l

M19 LUBE' OIL (OTHER THAN TURBINE) l N1 i

M9,10 SERVICE WATER ll COMMUNICATION N3 REFUELING INTERLOCK NS/N6 M23 PROCESS SAMPLING N1 4

M17 MAKE-UP WATER TREATMENT N5 M18 MAKE-UP WATER DEMINERALIZER l

NS

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l IV.

HEATING, VENTILATION AIR COND. & COOLING M78 CONTROL ROOM & CONTROL STRUCT. VENT.

L M78 CONTROL ROOM (HVAC)

M78 AUXILIARY EQUIPMENT ROOri (HVAC)

M78 EMERGENCY FRESH AIR SUPPLY j

M78 CONTROL STRUCTURE (HVAC) FROM TURBINE ENCLOUSRE M78 SGTS. EQUIPMENT COMPARTMENT (HVAC)

M78 EMERGENCY SWITCHGEAR & BATTERY COMP. &' BATTERY l 2

M76 REACTOR ENCLOSURE VENTILATION l

j M76 REACTOR ENCLOSURE (HVAC) FOR NORMAL OPERATION l

M76 SAFETY RELATED REACTOR INCLCSURE (AIR COOL)

M79 RADWASTE ENCLOSURE VENTILATION M75 TURBINE ENCLOSURE VENTILATION M76 PRIMARY CONTAINMENT VENTILATION l

M57-CONTAINMENT ATMOSPHERIC CONTROL l

M77 DRYWELL AIR COOLING l

M81 DIESEL - GENERATOR ENCLOSURE VENT.

N6/N8 M81

= SPRAY POND PUMP STRUCTURE VENTILATION-N5 M82 HOT ~ MAINTENANCE SHOP VENTILATION l

N3 M81,80 MISCELLANEOUS STRUCTURE VENTILATION N3

-83 l

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POWER DISTRIBUTION

.NON-CLASS 1E AC

.l-CLASS 1E AC l_

CLASS 1E DC l

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MPL SYSTEMS REASON I.

REACTOR SYSTEMS l

RPS l

N8 M55 HPCI l

N8 M41,42 ADS l

N8 M52 CORE SPRAY l

N8 M51 RHR l

N8 M41,42, PRIMARY CONT.& REACTOR VESSEL ISOLATION l

N8 60 l

M10 RHR SERVICE WATER l

Mll EMERGENCY SERVICE WATER l

N5 M57 COMBUSTIBLE GAS CONTROL l

N6 M57 PRIMARY CONT. VACUUM RELIEF SYSTEM l

N1 M40 MAIN STEAM LINE ISOL. VALVE LEAKAGE CONTROL l

N6/N5/N8 M76 STAND-BY GAS TREATMENT l

M76 REACTOR ENCLOSURE RECIRCULATION l

M76 REACTOR ENCLOSURE ISOLATION l

REMOTE SHUTDOWN l

N6 M48 STAND-BY LIQUID CONTROL (SLC) l N8 M49 REACTOR CORE ISOL. COOL (RCIC)

N8 NEUTRON MONITORING IRM/LPRM/APPM M41 SAFETY RELIEF, VALVE POSITION INDICATION l

N2 M59 CONTAINMENT INST. GAS SYSTEM AND ADS-CONTROL l

REACTOR MANUAL CONTROL l

M43 REACTOR RECIRCULATION l

M44 REACTOR WATER CLEAN-UP l

M30 POST ACCIDENT SAMPLING l

N6/N2 l

l II. TURBINE / GENERATOR SYSTEM l

M1 MAIN TURBINES l

TURBINE CONTROL l

M2 EXTRACTION STEAM l

M7 STEAM SEAL l

M1 TURBINE BY-PASS l

MS,9,2, CONDENSER l

1 l

M7 AIR REMOVAL l

CONDENSER TUBE LEAK DETECTION l

N5 M9,5,6, CONDENSATE PUMPS l

16 l

M2,3,4 HEATERS VENTS & DRAINS l

N5 M16~

CONDENSATE FILTER & DEMINERALIZER l

N5 M8 CONDENSATE & REFUELING WATER STORAGE AND l

N5 TRANSFER l

FEEDWATER/ CONDENSATE GEMERATOR EXCITATION l

M28 H

COOLING & CO PURGE l

2 2

GENERATOR LIQUID COOLING l

SEAL OIL l

BUS DUCT COOLING l

1-0402 5/3/84

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