ML20054C988

Advises That NRC Position Modified Re Reactor Protection Sys & ESF Actuation Sys.Proposed Tech Specs Encl

ML20054C988
Person / Time
Site:	Maine Yankee
Issue date:	03/31/1982
From:	Clark R Office of Nuclear Reactor Regulation
To:	Garrity J Maine Yankee
References
TAC-7089, NUDOCS 8204220215
Download: ML20054C988 (3)

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DJSTRIBUTION:

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-Ol(o MAR 311982 VD eket File NRC POR L PDR i

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Docket No. 50-309 ORB #3 Rdg a;

03 DEisenhut JHeltemes OELD 8

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g Mr. John H. Garrity, Senior Directof 8E Nuclear Engineering and Licensing Gray File Maine Yankee Atomic Power Company PMKreutzer-3 83 Edison Drive RAClark 9

Augusta Maine 04336 Econner CNelson 4

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Dear Mr. Garrity:

By letter dated July 15, 1981, you informed the staff that the infor-mation requested in our letter of April 16,1981 on Reactor Protection System (RPS) and Engineered Safety Features Actuation System (ESFAS) logic would be provided by the end of the 1982 refueling outage. Since issuance of the April 1981 letter, we have modified our position r

slightly. Two options are provided for licensees to follow.

Option 1 would allow the bypass of an inoperable channel for a period not to exceed 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> at which time the inoperable channel must be placed in the trip mode. Option 2 would allow the bypass of an inoperable channel in accordance with the requirements delineated in the Techni-cal Specifications (TS) Enclosure 1 Action Statement 2.

Option 2 is less restrictive than Option 1.

Option 1 The original TS proposed by the staff for plants requesting to operate as a two-out-of-three system was to require that the inoperable channel be placed in the tripped condition within one (1) hour. Subsequent to this requirement, 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> bypass was approved by the staff on various operating plants (Calvert Cliffs. St. Lucie 1, and Arkansas Nuclear One Unit 2) based on the staff's review of the RPS and ESFAS sensor channels for the adequacy of physical and electrical independence.

Based on all reviews of Combustion Engineering (CE) designed plants completed to date, we now conclude that there is no technical or safety basis for limiting the bypass of a channel to one hour rather than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.

Permitting 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> rather than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> prior to placing an inoperable channel in trip may, in fact, be a benefit to pla.nt safety by reducing the probability of inadvertent protection system actuations and by providing greater flexibility in performing maintenance and/or testing on an inoperable channel. SeTectfon of this option should result in application for TS in the form of Enclosure 3 to our letter of April 16, 1981.

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1 Option 2 If it can be verified that three protection system channels in two-out-of-three logic are sufficient to satisfy all protection system criteria, then one channel of a four channel system may be bypassed for a lengthy period of time with no degradation to safety. Action Statement 2 of the Enclosure 1 TS pages (San Onofre - Unit 2) may be proposed in place of Action 2 of Enclosure 3 of our April 16, 1981 letter.

delineates the criteria which must be satisfied to ensure that three channels are sufficient for plant protection. However, we believe that it is prudent that an inoperable channel be repaired and returned to service as quickly as practicable. Action Statement 2 of Enclosure 1 would allow the flexibility of continued plant operation with an inoper-able channel in bypass where it is not feasible to repair the channel (for example, if the failure is inside the containment in a location inaccessible during plant operation). The model TS however, do place responsibility on the licensee to repair the channel as quickly as possible and in any event during the first cold shutdown after the failure has occurred.

Option 1 may be implemented by a request from you without any further analyses or review of the protection system by either the staff or yoursel f.

Option 2 should be implemented only after you have requested this option and have verified to the staff that you have reviewed the plant design and determined that it complies in all respects to the criteria delineated in Enclosure 2.

No review would be required by the staff unless a significant question arises related to your review.

Application for the Option 1 or Option 2 TS should be submitted any time within the next 6 months. The issue should be resolved before startup from the subsequent scheduled refueling outage.

1 Sincerely,

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Original signed by Robert A. Clark Robert A. Clark, Chief Operating Reactors Branch #3 Division of Licensing

Enclosures:

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Maihe Yankee ' Atomic Power Company ec:

E. W. Thurlow, Pr'esident Mrs. L. Patricia Doyle, President Maine Yankee Atomic Power Company SAFE POWER FOR MAINE Edison Drive Post Office Box 774 Augusta, Maine.04336 Camden, Maine 04843 Mr. Donald E. Vandenburgh First Selectman of Wiscasset Vice President - Engineering Municipal Building Yankee Atomic Electric Company U. S. Route 1 20 Turnpike Road Wiscasset, Maine 04578 Westboro, Massachusetts 01581 John A. Ritsher, Esquire Atonic Safety and Licensing Board Ropes & Gray U.S. Nuclear Regulatory Commission 225 Franklin Street Washington, D. C.

20555 Boston, Massachusetts 02110 David Santee Miller, Esq.

Mr. Rufus E. Brown 213 Morgan Street, N. W.

Deputy Attorney General Washington, D. C.

20001 State of Maine Augusta, Maine 04330 Mr. Paul Swetland Resident Inspector / Maine Yankee Mr. Nicholas Barth c/o U.S.N.R.C.

Executive Director P. O. Box E Sheepscot Valley Conservation Wiscasset, Maine 04578 Association, Inc.

P. O. Box 125 Mr. Charles B. Brinkman Alan, Maine 04535 Manager - Washington Nuclear Operations

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Combustion Engineering Inc.

Wiscasset Public Library Association 4853 Cordell Avenue, Suite A-1 High Street Bethesda, Maryland 20014 Wiscasset, Maine 04578 Mr. Robert H. Groce Mr. Torbet H. Macdonald, Jr.

Senior Engineer - Licensing Office of Energy Resources Maine Yankee Atomic Power Company State House Station #E3 1671 Worcester Road Augusta, Maine 04333 Framingham, Massachusetts 01701 Robert M. Lazo, Esq., Chairman Atomic Safety and Licensing Board U.S. Environmental Protection Agency U.S. Nuclear Regulatory Commission Region I Office Washington, D. C.

20555 ATTN:

Regional Radiation Representative JFK Federal Building Dr. Cadet H. Hand, Jr., Director Boston,' Massachusetts 02203 Bodega Marine Laboratory University of California Bodega Bay, California 94923

.Mr. E. C. Wood, Plant Manager Maine Yankee Atomic Power Company State Planning Officer P. O. Box 3270 Executive Department Wiscasset, Maine 04578 189 State Street Augusta, Maine 04330 Regional' Administrator Nuclear Regulatory Commission, Region I Office of Executive Director for Operations 631 Park Avenue King of Prussia, Pennsylvania 19406

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ENCLOSURE I

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TABLE 3.3-1 (Continued)

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TABLE NOTATION

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With the protective system trip breakers in the closed position, the CEA x

drive spstem capable of CEA withdrawal, and fuel in the reactor vessel.

The provisions of Specification 3.0.4 are not applicable.

-4% of RATED THERMAL POWER; bypass Trip 'may be manually bypassed above 10shall,, e automatically

'(a) to 10)% of RATED THERMAL POWER.

Trip may be manually bypassed below 400 psia ~; bypass shall 'be automatically removed whenever pressurizer pressure is greater than.or -

(b) e, qual to 400 psia.

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-4% of RATED THERMAL POWER; bypass Trip may be manually bypassed below 10 (c) shall be autecatically removed when THERFAL POWER is greater than.or equal to 10 *% of RATED THERMAL POWER.

During testing pursuant to Special Test Exception 3.10.3, trip r.ay be manually bypassed below 1% of RATED THERMAL POWER; bypass shall be automatica11y' removed when THER POWER is greater than or equal to 1% of RATED THEP. MAL POWER. '

Trip may be bypassed during testing pursuant.to Special Test (d)

. Exception 3.10.3.

,(e)

See Speciai Test Exception,3'.10.2.

Eacn channel shali'be comprised of two trip breakers; actual trip logic (f) shall be. one-out-of two taken twice.

(g)', Trip.may be bypassed below 55% RATED THERMAL POWER.

ACTION STATENENTS With the number of channels OPERABLE one less than required by ACTION 1 restore the the Minimum Channels OPERABLE requirement, inoperable channel 'to OPERABLE status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or be'in

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at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and/or open the

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protective system trip breakers.,

With the number of channels OPERABLE one less than the To Number of Channels, STARTUP and/or POWER OPERATION may contin ACTION 2 provided the inoperable channel is placed-in the bypassed or.If t tripped condition within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.

bypassed, the desirability of maintaining this channel in the bypassed condition shall be reviewed in accordance with-The channel shall be returned to Specification 6.5.1.6k.

OPERABLE status no later than during the next COLD SHUTDOWN..

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U ADMINISTRATIVE CONTROLS MEETING FRE00ENCY -

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6.5.1.4 The OSRC shall meet at least once per calendar month and as ' convened by the OSRC Chair 5an or his designated alternate.

OUORUM 6.5.1.5 The minimum quorum of the OSRC necessary for the peric-- ace of the '

OSRC responsibility and authority provisions of these Technical Specifications shall consist of the Chair =an or his designated alternate and four members including alternates.

, RESPONSIBILITIES

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6.5.1.6 The Onsite Review Committee. shall be res'ponsible for:' '

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Review of 1) all procedures required by Specification 6.8 and changes a.

thereto, 2) all programs required 'by Specification 6.8 and changes-thereto, 3) any other proposed procedures or changes thereto as

, determined by the Station Manager to affect nuclear safety.

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b.

Review of all proposed tests and experjeents that affect nuclear safety.

c. ' Review of all proposed changes to Append.ix "A" Technical Specifications.

d.

Review of all proposed changes or modifications to unit systems or equipment that affect n'uclear safety.

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e.

Investigation of all violations of the Technical Specifications' including the preparation and forwardi,ng of reports covering.

evaluation and r,ecommendations to prevent recurrence to the Nuclear

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Control Board (NCB).

f.

Review of events requiring 24-hour written notification to the Commission.

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. Review of unit operations to detect potential nuclear safety hazards.

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Performance of special reviews, investigations or analyses and reports thereon as req 6ested by the Station Manager or the NCS.

1 1.

Review of the Security Plan and implementing procedures and shall l

submit recommended changes to the NCB.

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Revie'w of the Emergency Plan and implementing procedures and 'shall submit recommended changes to the NCB.

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Review and documentation of judgment coricerning prolonged operation irr bypass, channel trip, and/or repair of defective protection channels l

of process variables placed in bypass since the last OSRC, meeting.

SAN ONOFRE-UNIT 2 6-7

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. E14 CLOSURE 2

'DESIGft CRITERIA

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In'present and various past Combustion Engineering (CE) applications, applicants have proposed to operate four-channel protection systems (Reactor protection System and specific Engineered Safety Feature Systems) with one of the four channels of a given process variab'le in bypass for an indefinite period of time.

Operating reactor licensees who.. desire to use the' Technical Specifications of Enclosure 1 must verify that they have re- ~

viewed the design and installation of their protection system and determined th'at the system meets.the criteria below.

The iicensees must also confirm.

that detailed information verifying compliance with the criteria is avail -

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able at the licensee's facilities -Por staff audit.

Until the licensee's confirmation, that the protection system meets the criteria below has been completed and submitted to the staff,' bypass of a protection system channel -

should be limited to 48 hburs at which time the channel shall be placed in the trip mode.

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1.

High Energy Line Break The protection system should be reviewed for the ef.fects of high energy line breaks.

Each licensee must analyze the protection. system to verify that high energy'l.ine hazards in coincidence with the bypass of' a channel will not negate the minimum acceptable redundancy required by IEEE Std. 279-1971.

It should be noted that credit is not.to be s

taken for the " fail-safe" mode of the channels affected by high energy.

line b'reaks.

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2.

Sinole

• Failure In Combination With-prolonced Byoass Th'ere may be cases where the prolonged bypass of a specific protection channel in combination with a single failure might jeopardize plant protection (i.e., channels remaining will not sufficiently detect associated transients and accidents without causing unacceptable consequences such' as core damage, etc.)

The licensee should review the' accident analyses (i.e., rod drop accident, rod ejection, etc.) to verify' that the bypass of a specific protection channel in coincidence with a single failure of a redundant channel will not prevent re-

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..j quired protection for any transient or accident.

3.

Channel Independence The four protection ch.annels must be reviewed for physical in-

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fd dependence.

Each licensee should confirm',that the fou~r prctection channels as installed' meet the physical independence criteria of Regulatory Guide 1.75.

4.

Independence of the-Vital Buses

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Each plant must be reviewed for independence of the vital buses.

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The Combustion Engineering (CE) reactor protection system (RpS) is made up' of four (4) protection channels for each trip parameter.

Each p"arameter channel consists of bistable relays and associated contacts which are arranged into six log'ic AINDs (AB, AC, AD, BC, BD, '

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d CD matricies) which represent all possible coincidences of two com-binations (e.g., combinations of two-out-of-four logic).

Each logic matrix is powered by two of four Class lE independent 120 Vac' vita,1 buses as shown in. Figure 1.

This arrangement may challenge

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the isolation and hened independence of the redundant ac vital power l

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..' buses.

It.is typical of licensees using the CE design to" assure that the indeperidence of these buses is maintained through th'e use... -

of qualified isolat6rs.

.a Licensees desiring to use the Technical Specifications of Enclosure 1 should confirm that tests and analyses have been performed to demonstrate independence of the redundant vita'l buses.

The. tests-and' supporting information should include:-.

a) The use of a plant.-specific mock-up representing one protection logic matrix system (i.e., two matrix power e

sup' plies, each with its own simulated 120 Vac vital bus supply, matrix relays, bistable power supplies, bistable l

trip units, and isolation circuitry),.

b) The application of surges (internal and external transient voltages) and faults (including continuous phase-to-phase.

short-circuits, phase-to-ground short-circuits and the

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application of continuous external h' gh voltages) to t'he

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i simulated 120 Vac vital bus supplying power to an associated matrix power supply,.

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cJ Application' of 'the surges ind. faults between each matrix power supply input conductor and. ground (common mode) and across (line'-

to-line) the matrix power supply input conductors (trans' verse mode), i d) Monitoring the redundant simulated 120 Vac vital bus supplying power to its matrix power supply 'to measure any effect as a re-sult of application of the faults or surges on the other bus, 4

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formed.

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Licensees desiring to use the Technical Specifications of Enclosure 1 should confirm that sufficient tests and analyses have been per-formed to assure that with a channel bypassed, a vital bus single failure will not negate the required protective function.

The tests and supporting information should include:

a) The use of a plant-specific mock-up representing one pro-tection logic matrix system (i..e;, two matrix power supplies, each with its own simulated 120 Vac. vital bus supply, matrix -

relays, bistable power supplies, bistable trip units', and

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isolation circu,itry),

b) The application of surges (internal and external transient voltages) and faults -(including continuous phase-to-phase short circuits, phase-to-ground short-circutts and the application.of continuous external high voltages) to the simulated 120 Vac vital bus supplying power to an associated matrix power supply, cl. The application of surges and faults between each matrix power supply input conductor and ground (common mode) and across (line-to-line) the matrix power supply input con-ductors (transverse mode),

d) Moni.toring the auctioneered matrix. power supply output to measure l

any effect on th'e. logic matrix circuitry as a resul't of application of th faults or surges, t

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e)

Verification that during and after the application of the

- ' surges and faults, the protection circuits will-perform th'eir protective actions, f)

Justification' that the faults and surges used ~during the

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testing exceed the maximum worst-case failures which could occur within the protection systems circuits.

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