ML20054C820
| ML20054C820 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun, San Onofre  |
| Issue date: | 03/31/1982 |
| From: | Clark R Office of Nuclear Reactor Regulation |
| To: | William Jones OMAHA PUBLIC POWER DISTRICT |
| References | |
| TAC-7089, NUDOCS 8204210726 | |
| Download: ML20054C820 (10) | |
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31 W DISTRIBUTION:
docket File NRC PDR Docket No. 50-285 NS ORB #3 Rdg
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g DEisenhut JHeltemes t
Mr. W. C. Jones g
Division Manager Production O
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t' "#ER 8 98b 2 Operations
'I' I&E Omaha Public Power District Gray File 1623 Harney Street Omaha, Nebraska 68102 C
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Dear Mr. Jones:
4 ur ny ro By letter dated July 22, 1981, you made application for a license change with regard to the independence of the four channel Reactor Protection System (RPS) and the Engineered Safety Features Actuation System (ESFAS) measurement logic in response to our April 16, 1981 letter. Since issuance of the April 1981 letter, we have modified our position 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 inoparable channel must be placed in the trip mode.
Option 2 would allow the bypass of an in-operable channel in accordance with the requirements delineated in the Technical 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 plant safety by reducing the probability of inadvertent protection system jactuations and by providing greater flexibility in performing maintenance and/or testing on an inoperable channel. Select' ion of this option should result in application for TS in the form Lf Enclosure 3 to our letter of April 16, 1981 8204210726 820331 PDR ADOCK 05000285 P
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OFFICIAL RECORD COPY usom mi-muo anc rosu m oomscu oua
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 Er. closure 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.
Your July 22, 1981 application is of the Option 1 form and can be issued when the additional information, requested orally by the staff, is submitted.
It is our understanding that Option 2 is not being considered at this time. However, we feel obligated to offer Option 2 in case you desire in the future to undertake a plant design review to determine the degree of compliance with the criteria delineated in Enclosure 2.
Sincerely.
Original signed by Robert A. Clark Robert A. Clark, Chief Operating Reactors Branch #3 Division of Licensing Enclosures : As stated cc: See next page E',$.$.kefk.IE.:
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Omaha Public Power. District cc:
Marilyn T. Shaw, Esq.
LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.
Washington, D. C.
20036 Mr. Jack Jensen Chairman, Washington County Board of Supervisors Blair, Nebraska 68023 U.S. Environmental Protection Agency Region VII ATTN: Regional Radiation Representative 324 East lith Street Kansas City, Missouri 64106 Mr. Frank Gibson W. Dale Clark Library 215 South 15th Street Omaha, Nebraska 68102 Alan H. Kirshen, Esq.
Fellman, Ramsey & Kirshen 1166 Woodmen Tower Omaha, Nebraska 68102 Mr. Larry Yandel.1 e
U.S.N.R.C. Resident Inspector P. O. Box 309 Fort Calhoun, Nebraska 68023 Mr. Charles B. Brinkman Manager - Washington Nuclear Operations C-E Power Systems Combustion Engineering, Inc.
4853 Cordell Avenue, Suite A-1 Bethesda, Maryland 20014 Regional Administrator Nuclear Regulatory Commission, Region IV Office of Executive Director for Operations 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011
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4 ENCLOSURE I e
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TABLE 3.3-1 (Continued)
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TABLE NOTATION With the protective system trip br'eakers in the closed position, the CEA n
drive system capable of CEA withdrawal,.and. fuel in the reactor vessel.
The provisions of Spec'fication 3.0.4 are not applicable.
~4% of RATED THERMAL POWER; bypass Trip [may be manually bypassed above 10shal1 be automatic
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(a) e to 10 '% of RATED THERMAL POWER.
Trip may be manually bypassed belos 400 psia; bypas (b) equal to 400 psia; Trip tilay be manually bypassed below 10'4% of RATED THERMAL P0W shall be ' automatically removed when THERMAL POWER is greater than.or (c)
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During testing pursuant to equal to 10 *% of RATED THERMAL POWER.
Special Test Exception 3.10.3, trip may be manually bypassed be RATED THERMAL POWER;. bypass shall 'be automatically' remove POWER is greater than or equal to 1% of RATED THERMAL' POWER.
Trip ::iay be bypassed during testing pursuant.to Special Test (d)
. Exception 3.10.3.
(e)
See Speciai Test Exception 3;10.2.
Each channel shall' b'e comprised of two trip, breakers,; actual trip l (f) shall.be. one-out-of two taken twice.
(g)'. Trip Jmay be bypassed,below 55% RATED THERMAL POWER.
l ACTION STATEMENTS With the number of channels OPERABLE one less than require l
the Minimum Channels OPERABLE requirement,, restore the ACTION 1 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 /> o E
at least HOT STANDBY within the next 6-hours and/or open the protective system trip-breakers.,
With the number of channels OPERAB'LE ACTION 2 provided the inoperable channel is placed-in the bypassed 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 bypassed condition shall be reviewed in accordance w OPERABLE status no later than during the next COLD SHU Specification 6.5.1.6k.
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SAN CNOFRE-UNIT 2
x MD E & M V l0PY ADMINISTRdTIVE CONTROLS MEETING FREOUENCY 6.5.1.4 The OSRC shall meet at least once per calendar month and as ' convened by the OSRC Chairman or his designated alternate.
OUORUM The minimum quorum of the OSRC necessary for the performance of the 6.5.1.5 OSRC responsibility and authority provisions of these Technical Specifications shall consist of the Chairman or his designated alternate and four members including alternates.
RESPONSIBILITIES 6.5.1.6 The Onsite Review Committee, shall be res'ponsible for:'
..y Review of 1)'all procedures required by Specif.ication 6.8 and chang s a.
thereto, 2) all programs required by Specification 6.8 and changes
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thereto, 3) any other proposed procedures or changes thereto as
. determined by the Station Manager to affect nuclear safety.
Review of all proposed tests and exp.erjments that affect nuclear
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safety.
- c. ' Review of all proposed changes to Append.ix "A" Technical Specifications.
Review of all proposed changes or modifications to unit systems or d.
.,.l-equipment that affect nuclear safety.
. Investigation of all violations of the Technical Specifications'
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- including the preparation and forwardi.ng of reports covering e.
evaluation and r.ecominendatioris to prevent recurrence to the Nuclear
9 Control Board (NCB).
si Review of events requiring 24-hour written notification to the f.
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Commission.
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, Review of unit operations'to detect potential nuclear safety hazards.
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Performance of special ieviews, investigations or analyses and reports thereon as requested by the Station Manager or the NCS.
h.'
Review of the Security Plan and irnplementing procedures and shall i.
submit recommended changes to the NCS.
Review of the Emergency Plan and implementing procedures and 'shall j.
submit recommended changes to the NCS.
Review and documentation of judgment concerning prolonged operatio bypass, channe1. trip, and/or repair of defective protection chann
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of process variables placed in bypass since the last OSRC.rneeting.
6-7 SAN ONOFRE-UNIT 2
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ENCLOSURE 2
-DESIGN CRITERIA In present and various past Combustion Engineering (CE) applications, ap'plicants 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 ~proce'ss variable in~ bypass for an indefinite period of time.
Operating reactor licensees who. desire to use
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the' Technical Specifications of Enclosure 1 m t verify that they have re-viewed the design and installation of their protection system and determined that the system meets the criteria below; The licensees must also confirm.
that deta'iled information verifying compliance with the criteria is avail--
able.at_ the licensee's facilitiesfor. staff audit.
Until the licensee's confirmation. that the p,rotection system meets the criteria below has
.been coii:pleted and submitted to the staff,' bypass of a proteci. ion system ch should be' limited to 48 hburs. at which time the channel shal) 5e placed in the trip mode.
1.
High' Energy Line Break.
The protection system should be reviewed for the effects of high energy line breaks.
Each licensee must analyze the protection. system to, verify that high energy'line hazards in coincidence with the bypass of' a channel will not negate the mir.imum, acceptable redundancy required by IEEE Std. 279-1971.
It should be noted that credit is not to be taken for the " fait-safe" mode of the channels affected by high energy.
line breaks.
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Sinole Failure In Combination With prolonaed Byoass Th'ere may be cases where the prolonged bypass pf a specific protectio ~n 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 licensea should review the accident analyses..(i.e, rod drop accident, rpd: ejection,:.etc.) to verify that the bypass of a specific,p,otection. channel in coincidence r
with a single failure of a redundant channel will not prevent re-A quired protection for a'ny ' transient or accident.
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3.
. Channel Indepenifence
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7, The four protei: tion channels must be revieweh for physical'in-e.
'I-Each lice'nsee should confirm ~that the four protection dependence.
channels as installed meet the physical independence criteria of
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Independence of the Vital Buses _ _
Each plant mus.t be reviewed for independence of the vital-buses.
The Combustion Engineering (CE) reactor protection system (RPS) is made up of foui- (4) protection channels for each trip parameter, l '.
Each p'arameter channel consists of bistable relays and associated l
l contacts which are arranged into six logic AiiDs (AB, AC, AD, B CD matricies) which represent all possible coinc.idences of two com-(
binations (e.g., combinations of two-aut-of-four logic).
1 Each logic matrix is powe ed by two of four Class 1E in~ dependent 120 Vac v. ital. buses as shown in Figure 1.
This arrangement may challen the isolation and hence independence of the. redundant :c vital power
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It <is typiial of licensees using the CE design to assure
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that the independence of these buses is maintain ~ed through th'e use
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of qualified isolato'rs'
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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. vital buses.
The. tests.
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and supporting information should inglude;.
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a) -The use of a plant.-specific mock-up representing one l
piotection. 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 isolation circuitry)..
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b) The application of surges (internal and external transient voltages) and faults '(including continuous phase-to-phase. -
short-circuits, phase-to-ground short-circuits an,d the application of continuous external high voltages) to t'he ;
simulated 120 Vac vital bus supplying power to an associated
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matrix power su'pply, c) 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 cond'ubtors (trans' verse mode),
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 o'..ler bus, g
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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
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relays, bistable power supplies, bistable trip units', and isolation circu,itry),
b) 1he application of surges (internal and external transient voltages) and faults (including continuous phase-to-phase short circuits, phase-to-ground short-circuits 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 any.effect on the logic matrix circuitry as a resul't of application of the faults or. surges,
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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 testing exceed the maxirmm worst-case failures which could occur within the protection systems circuits.
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