ML20002A348
| ML20002A348 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 11/11/1975 |
| From: | Burger A Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8011130316 | |
| Download: ML20002A348 (6) | |
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UNITED STATES g.,.;;;;
V NUCLEAR REGULATORY COMMISSIG2
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DOCKET NO.:
50-29 DATE:
November.11, 1975 7:
- LICENSEE:
Yankee Atomic Electric Company (Yankeel
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FACILITY:
-Yankee-Rowe
~C.Z SUhB!ARY OF MEETING HELD ON NOVEMBER 6, 1975, TO DISCUSS DIE CORE XII ECCS SUBMITTAL IN REGARDS TO SINGLE FAILURES E:==
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On November 6, 1975, we met with representatives of Yankee to discuss' single failures in the Yankee-Rowe ECCS, in connection with Yankee's ECCS submittal for operation of Yankee-Rowe with Core XII.
'3 A list of attendees is attached.
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During the review of Yankee's ECCS cooling performance evaluation for
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Core XII'(scheduled for operation by December 1,1975), the staff 51 identified several manually-controlled, electrically-operated valves'
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in the.ECCS which could adversely affect ECCS performance if any one SE4E of these valves failed toJfunction due to operator error or spurious
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failure.
In their Core XII submittal-Yankee proposed to remove valve operating switch handles and place them under administrative control
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to preclude single operator errors..However, Yankee did not propose any FR ?.
measures to preclude spurious valve failures. The staff had advised b *;
Yankce that measures to preclude spurious failures of ECCS valves at Yankee-Rowe must be implemented in order to meet the single failure
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assumption ~ in the Core XII ECCS analysis for Yankee-Rowe.
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The purpose of this meeting was to review the operation of the ECCS
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components including valves in detail and' to explore what acceptabic measures can be taken to preclude valve failures that could adversely affect the ECCS performances.
The significant highlights of this meeting are summarized below.
Yankee described in detail the operation of the ECCS from receipt of a safety injection signal through the long-term recirculation
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heat removal phase.
Yankee explained the function of each valve which the staff had previously identified as not meeting the
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single failure criterion ~(see Attachment).
Yankee stated that they had no,t proposed measures to preclude
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spurious fcilures of motor operated valves (MOV's)-because they thought that spurious (passive) failures of MOV's need not be considered in the short-term phase of ECCS operation.
For the
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long-term at spurious failure of MOV's (except two valves in the recirculation system cross-over to the hotleg) can be tolerated because'of the availabic redundant flow path in the ECCS. We 80n13o3/6 g
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. November 11, 197S explained to Yankee that this is not in accordance with the staff's position and exampics were given Yankee why short-term spurious failures of MOV's cannot be ignored.
A discussion of functions of each valve identifed in the attachment showed that the Yankee-Rowe ECCS has redundant flow paths and associated MOV's.
The ECCS also has capabilitics provided by several MOV's for operating flexibility that could be removed (by racking out power) without decreasing the safety margins in the ECCS cooling performance evaluation or steam line break accident analysis.
The staff's position is that racking out power from the MOV breakers
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with the valve in the operating position is an acceptable short-term fix to preclude spurious valve motion.
In cases where the operating positions of M0V's must be changed, manual restoration of power to p
the valves is acceptable provided sufficient time (--15 minutes) is
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available before valve motion is necessary.
j-Examination of the control equipment for the ECCS MOV's has shown
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that several have breakers which are located in a motor control center that would be inaccessible following a LOCA.
Therefore, manual restoration of power to these MOV's would not be possible.
Many of the MOV's with breakers in the inaccessible area could be permanently racked out, with consequent loss of some operating ficxibility but without loss of safety margins.
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Valves Sl-MOV-4 and S1-MOV-46 are powered from a single bus.
Yankee agreed to connect the valve motors to separate busses.
Also, these valves are connected to breakers which are inaccessible following a LOCA.
Therefore, a temporary fix to preclude spurious operation does not appear to be feasible, because restoration of power to these valves is required for performance of ECCS functions.
Spurious opening of solenoid valves (S1-SV-56 or SI-SV-57) at the time of LOCA could significantly reduce the nitrogen pressure in the accumulator. Yankee was requested to provide information that will show that such a single failure would not reduce injection flow from the accumulator below that assumed in the ECCS analysis.
Yankee agreed to defeat the automatic throwover of the two electrical emergency busses and to use the manual switch for load transfer.
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e Yankee agreed to develop short-term and permanent fixes,using the guidance given by the staff during this meeting.
It was pointed out to Yankee that they should provide the information on proposed H
acceptabic short-term fixes promptly to enable the staff' to complete the Core XII ECCS review in time for their scheduled December 1, 1975, resumption of operation.
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Alfred Burger, Project Manager Operating Reactors Branch #1 Division of Reactor Licensing
Enclosures:
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List of Attendees
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Single Failures cc: See next page i
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Enclosura 1 I
LIST OF ATTENDEES NRC a
A. Burger H. Vandermolen R. Fitzpatrick
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D. Tondi K. I. Pare:cwski S. Kucharski C. Berlinger R. Baer T. M. Novak r.
Yankee F. D. Baxter P. E. Laiko G. Tsouderos P Raincy R. Shonc e
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Enclosurc 2 SINGLE FAILUPIS MOV Co>fPONENT FU'.CTION FAILURE MODE SI-MOV-1 Accumulator Isolation Inadvertent closing of this valve.
valve would stop accunulator flow into system.
CS-MOV-535 Containment Isolation This valve is in series with the valve.
accumulator isolation valvc.-
Inadvertent closing would stop all flow to systen.
SI-MOV-4 Crossover fron LPSI Spurious actuation of this valve discharge to RPSI would prevent the boosting of pumps.
flow to the 11 PSI pe=ps f or small.
break capabilities.
CS-MOV-533 Rel;ulates flow from the Frenature closure can reduce LPS1 puups.
injection to less than required flou rates.
SI-MOV-46 FJow control f rom liPSI If this valve cheu]d spuriously
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pumps.
close flow uould be cut off frc-the UPSI pumps.
SV-16SV-2 Nitrogen pilot relief Pretature opening would result if valves.
decreasing the accunulator driv.;
force.
Cli-MOV-52 3 Isolation valve from closure of these valves during
& Cit-MOV-524 charging pump dischargc long tern cooling rould cut eff header to hot leg of loop flow to hot leg.
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(provides i!.L. Inj. for long term recirc.).
MC-MOV-301 RCS Loop isolation valves Closure of any of these valves 302, 309, would Isolate a RCS loop.
310, 318, 319, 3?5 and 326.
CS-MOV-49 11 PSI Test /Recire. Line Fail closed - overheat purp.
valve (Mini-flow) 1 Cit-MOV-522 Isolation valve between Identified by licensee, not charging pump discharge clear what probica exists for headcr + LPSI discharge this valve.
CS-MOV-532 Recirculdtion valve used opening of this valve during a for testing pump (Lpsy)
LOCA would reduce flow fron LPSI P90Ff'DRIGINAL
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i Meeting Summary for Yankee-Rowe 4--
November 11, 1975 cc: Licensee H.' Denton
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NRC PDR B Grimes
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Local PDR M. B. Spangler R. C. DeYoung R. L. Ballard 1
D. B. Vassallo J. Kastner
="9 W. R. bulter W. P. Gammill
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O. D. Parr Project Manager V. A.-Moore Attorney, OELD J. F. Stol:
OIGE (3) 4 K. Kniel S. M.-Sheppard A. Schwencer NRC Participants D. J. Skovholt R. Fraley., ACRS (16)
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P. F. Collins T. B. Abernathy, DTIE R. H. Vollmer D.-Eisenhut R. W. Houston B. Rusche 7--
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-K. R. Goller.
E. Case R. A. Purple R. Boyd D. L. Ziemann
. EP Project Manager 1
G. Lear
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R. Reid hxx Reading
.l R. P. Denise i
R. A. Clark F
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l T.~ P. Speis p.
D. R. Muller G. W. Knighton g..
G. K. Dicker B. J. Youngblood i
W. H. Regan S. Varga T. J. Carter R. Heineman R. L. Tedesco J. Collins
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G. Lainas V. Benaroya R. R. Maccary
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J..P. Knight S. S. Pawlicki L. C. Shao V. Stello D. F. Ross b
T. M. Novak y
T. A.-Ippolito E{
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