ML20100B936
| ML20100B936 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 11/07/1984 |
| From: | Kemper J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| CON-#185-081, CON-#185-81 OL, NUDOCS 8503280669 | |
| Download: ML20100B936 (6) | |
Text
09>l p,CORRESPONDENGE o
PHILADELPHIA ELECTRIC COMPANY
.rc 2301 MARKET STREET P.O. BOX 8699 PHILA D ELF 8Fil A. lPA.#1910i'lIO3 NOV 071984 2:si s4i.4so2 l
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Richard W. Starostecki, Director Docket Nos. 50-352 CL Division of Project and Resident Programs 50-353 o '
United States Regulatory Ccmnission - Region 1 631 Park Avenue King of Prussia, PA 19406 1
SUBJECT:
Limerick Generating Station, Units I and 2 Technical Review of the Emergency Service Water System by Brookhaven Natlonal Laboratory j
REFERENCE:
Letter, R. W. Starosteckl to J. S. Kenper dated October 4, 1984
Dear Mr. StarosteckI:
This is in response to the referenced letter which requested our corrments on the Technical Reviews of the Emergency Service Water System by Brookhaven Natlonal Laboratory (BNL).
As a preliminary matter, it appears to us that the use of the system level fault trees, as was done by BNL to identify key portions of ESW reliability, has the potential of assuring an effective technical review. However, we do not believe that the areas of concen-tration for this inspection reflect insights or understandings gained q
as a result of the PRA. Most areas of Investigation were related to construction or procedures completion status. Some of the PRA system
" Insights" which were pursued are not germane to the reliability of the ESW system or the plant.
We believe that the effectiveness of PRA based Inspections would be enhanced if our Engineering Department was contacted in advance of all such future inspections.
In this way we will be able to provide individuals familiar with the design and PRA modeling of systems being reviewed.
Our responses to each of the open items identified in Section 10.1 of the Technical Review report are as follows:
4 1)
Debris in control room cabinets At the time of the inspection it was noted that the EWS control room cabinet contained dirt and debris.
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1 This is not sn unexpected situation given the construction status of the plant at the time of the BNL site i
visit. A construction cleanup of all Control Room cabinets and panels was perforvned in September to remove debris.
2)
Recalibration of instruments i
The Inspection report notes that a program did not i
appear to exist to assure periodic calibration of ESW control room instrunents.
l These instrunents are on a 2 year cycle for recalibration. Relevant ESW Instrunents are verified to be within this 2 year calibration period during each l
Surveillance Test.
3)
Automatic return of ESW valves The Inspection report properly describes the design for those ESW valves which are automatically operated. Each of i
the two ESW loops Is supplied wIth cooling water by two ESW l
punps which are powered from separate electrical divisions.
Automatic, redundant, Isolation valves are employed at the Interfaces with non-safety grade service water systems.
These valves are interlocked with the breakers for the ESW l
punp corresponding to their electrical division. Thus, the ESW supply and return line interfaces are designed to withstand a single active failure. This is the system configuration which was rnodeled in the LGS PRA. The inspection report states that this design may be contrary to IEEE-279 para. 4.16 and NRC Bulletin 80-06 Item 2.
The system is automatically actuated when the diesel generators start (ESF actuation signal). The diesel l
generator start signal (diesel. generator up to speed or i
diesel generator connected to its respective safeguard bus, and safeguard bus voltage is sufficient) causes the ESW purp to start. The ESW system aligrynent valves autcznatically line-up to supply the ESW purp flow to selected plant loads and to block the nonnat service water flow to those loads.
These valves are only required to operate when the ESW purps start and continue to run.
.The ESW system continues to operate in the emergency mode even after the diesel generator start signal is reset.
The ESW system is' tripped off either by deliberate operator t
action to manually trip the ESW punps or by operation of
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protective devices as identified in EWS system design basis.
These two actions cause the ESW pums to trip off and the ESW system alignment valves to return to their nonnel position, conpletely-shutting down the ESW system. Manual control of the pums and the system aligrvnent valves remain available to the operator.
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We believe the present design of the ESW is safe, sufficient and fully meets the requirements of IEEE-279 para.
1 4.16 and NRC Bulletin 80-06 Item 2.
The ESW system starts and aligns to the emergency mode when the ESF actuation l.
signal is sensed and continues to operate in the emergency mode until reset by deliberate operator action to manually trip the system or by operation of protective devices as Identified in the ESW system design basis; fully meeting the I
requirement of IEEE-279 para. 4.16.
When operating in the J
emergency mode after an ESF actuation signal is sensed, the ESW system wil: not reset and automatically return to the j
normal mode when the ESF actuation signal is reset, fully meeting the requirements of NRC Bulletin 80-06 Item 2.
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Redundancy is designed into the ESW system so that any j
single active failure, including loss of an ESW punp, will not prevent ESW from satisfying its safety design basis.
4)
Wet pit level detection The inspection report properly describes the design of the water supplies to the ESW pum wet pits. The wet pits can be supplied frcm either the spray pond or the cooling tower basins. One of the potential modes of ESW failure j
modeled in the LGS PRA was loss of wet pit water suppl.y.
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i This failure mode was assigned a probability appropriate for the design configuration. During the site Inspection, it was noted that providing-a wet pit level alarm could further increase the reliability of ESW and thereby reduce core t
damage frequency.
I Examination of the ESW fault tree Indicates that inclusion of a wet pit level alann would have an inconse-quential effect on ESW reliability.g Even if such an alann were to be provided, operator action would be required within a short period of time to avoid loss of punp suction in the l
unilkely event that all of the water supplies to the wet pits.
were closed.
If the pums did trip due to such an occurrence, operator action to reestablish flow to the wet pits' and restart the pums will allow ESW system restoration.
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5)
Ability of one ESW pum to provide design flow rate The BNL report notes some apparent discrepancies in the ESW pum discharge flow rates.
At the time of the BNL site visit, preoperational testing and flow balan:Ing of the ESW system had not been l
fully completed. Testing has subsequently been completed to verify adequate flows to all essential Unit 1 equipment on both the "A" and "0" ESW loops and operating procedures have been Irmlemented which 5 0 strict operation to modes which have i
been fully denonstrated by test.
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_4 6)
No preoperational tests done on ESW manual valves and check valves The BNL report notes the operability of certain ESW system check valves and manual valves was not verified as part of the LGS Preoperational Test Program.
The operability of the ESW check valves was verified E
under ESW system Surveillance Tests (ST1-011-490-1, ST6-011-231-0, ST6-011-232-0). System manual valves were i
verified to be operational as part of the relevant component
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i tests and system operating procedures ("S" procedures).
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h 7)
Setpoints not included in all Annunciator Response Cards j
The inspection report properly states that' Annunciator e
Responses Cards (ARC's) had not been cormleted for ESW and a
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i nmt>er of other systems at the time of the site visit.
1 ARC's have now been prepared for all safety-related control room annunciators. These ARC's include alarm setpoints in accordance with our FSAR Chapter 13 conmitment.
7 8)
No off-normal procedures for ESW The BNL report notes that there were no procedures for off-normal operation of ESW.
As described in 5, above, the ESW operating procedures have been required to include restrictions on off-normal riodes of operation which have not yet been fully verified by test.
9)
Program for locked valves and contrpi room key-locked handswitches N
i The inspection report states that the program for 4
lock / key control for control room handswitches was not finalized and that system valve lineup check-off IIsts did
-not fully reflect the valve locking conmitments. The "cenmitments" which BNL referred to regarding locked closed valves Is believed to refer to the modeling of valve position In the PRA system level fault trees. Sultably low probabilities were assigned to misalignment of valves which h
were Indicated on the PSID's to be physically locked closed h
or provided with a key-locked switch in the control roon.
The appropriate information on locked valves has been included in the system check off IIsts. Keys for valve locks
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will be controlled by the Shift Supervisor via the procedure for the controlled key cabinet and issuance system. Keys for key-locked handswitches will also be controlled by this l
procedure.
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- 10) Tech. Spec. Outage time review for shared systems The BNL report states that credit has been teken in the Technical Specifications for the availability of all four ESW pumps for Unit 1 operation and that the limits so derived may not be appropriate for two unit operation.
The current Technical Specifications for ESW reflect the
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requirements of operation for two unit operation. However, i
we concur that a thorough review of the Tech. Specs. for shared systems should be perfonned before Unit 2 becomes operatlonal.
Please contact me if you require any additional Information.
Sincerely, ARD/dg/10318407 Copy to: See Attached Service List A. Schwencer i
1
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-e cc: Judge Helen F. Hoyt Judge derry Harbour Judge Richard F. Cole Judge Christine N. Kohl Judge Gary J. Edles Judge Reginald L. Gotchy Troy B. Conner, Jr., Esq.
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Ann P. Hodgdon, Esq.
Mr. Frank R. Romano Mr. Robert L. Anthony Ms. Phyllis Zitzer Charles W. Elliot, Esq.
Zori G. Ferkin, Esq.
Mr. Thomas Gerusky Director, Penna. Emergency Management Agency Angus R. Love, Esq.
David Wersan, Esq.
Robert J. Sugarman, Esq.
Martha W. Bush, Esq.
Spence W. Perry, Esq.
Jay M. Gutlerrez, Esq.
Atomic Safety & Licensing Appeal Board Atomic Safety & Licensing Board Panel Docket & Service Section Mr. James Wiggins Mr. Timothy R. S. Campbell 9
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