ML20063H738

Discusses Info Re Use of Bypass Test Capability for Instrumentation Maint

ML20063H738
Person / Time
Site:	Vogtle
Issue date:	02/10/1994
From:	Mccoy C GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LCV-0290, LCV-290, NUDOCS 9402220164
Download: ML20063H738 (3)

Text

Georgia Power Company 40 inverness Center Parkway Post Off ce Box 1295 Birming sam. Alabama 35201 Teleonone 205 877 7122 Georgia Power C. K. McCoy Vce Premdent NucNr Vogys Progect the SO: Ahem citx:tlnc system February 10, 1994 LCV-0290 j

Docket Nos. 50-424 50425 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 Gentlemen:

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VOGTLE ELECTRIC GENERATING PLANT USE OF BYPASS TEST CAPABILITY -

FOR INSTRUMENTATION MAINTENANCE By letter dated September 30,1993, the NRC approved changes to the Vogtle Electric Generating Plant (VEGP) Unit I and 2 Technical Specifications (TS) that allow routine testing of the engineered safety features actuation system (ESFAS) and reactor trip system (RTS) instrumentation in bypass without the use of temporaryjumpers or lifted leads. Prior to the NRC approval of September 30,1993, Georgia Power Can.pany (GPC) responded to an NRC request l

for additional information by letter dated July 26,1993. In that letter, GPC stated that "the BTI l

was designed with the intent to bypass a channel only for the purpose of the following:

Surveillance testing with the comparator outputs bypassed rather than tripped.

e Surveillance testing on an active channel in the presence of an existing channel failure j

which caused a redundant channel to be declared inoperable."

On Febmary 2,1994, a Unit 1 pressurizer pressure transmitter began to exhibit drill and it was taken out of service for maintenance. In keeping with the above statement from the July 26, 1993, letter, the affected channel was placed in the tripped condition rather than use the bypass capability. Subsequently, as the transmitter was being removed, an isolation valve on its associated reference leg was bumped and the reference leg was momentarily vented. This reference leg is shared by a second pressurizer pressure transmitter, and the momentary venting caused the second transmitter to sense a low pressure condition which, in the presence of the trip signal from the first channel, was sufficient to result in a reactor trip and safety injection. Had the inoperable channel been placed in bypass prior to the maintenance, a reactor trip and safety injection could have been avoided.

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f U. S. Nuclear Regulatory Commission LCV-0290 Page 2 di i The existing VEGP TS allow 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> for placing an i

of the RTS and to use the bypass capability for maintenance as well as f h

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l nnot be could be placed in the bypassed condition for a maximum of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. If the c an i

restored to service in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, it will be placed in the tripped condit on.

NRC Safety Evaluation Report (SER) for Westinghouse Topical Reports Supplement 2 and WCAP-10271 Supplement 2, Revision 1, " Evaluati Frequencies and Out of Service Times for the Enginee i

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f Systems," dated February 22,1989.

the analog channels may be in bypass for the duration of the maintenance f

py of the that they are placed in the tripped condition after 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. (See enclosure or a co fhb ss subject SER.) All administrative controls that are presently applied to the us d

ELV-03878, dated capability will remain in effect as described to the NRC in our correspon enceFurthe March 1,1993, and LCV-0061, dated July 26,1993.

hi h has expand the use of the bypass capability to any other instrumentation othe i

the already been presented to the NRC in ELV-03878. F i

t t er of the bypass capability states that the approved ame i

t trip or ESFAS actuation.

Therefore, based on our recent experience, existing administrative controls f

dNRC and the fact the proposed use of the bypass capability is supported by the above re SERs, GPC believes that the proposed use of the bypass capability is s purpose of avoiding unnecessary reactor trips and ESFAS actuation d it is our telephone conversation was held with NRC-Region II, NRC-NRR, and GPC an bility.

understanding that the NRC staff agrees with the propo the bypass capability for maintenance purposes.

Sincerely, l

C. K. McCoy CKM/NJS Enclosure

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U. S. Nuclear Regulatory Commission LCV-0290 Page 3 xc:

Georgia Power Company Mr. J. B. Beasley, Jr.

Mr. M. Sheibani NORMS U. S. Nuclear Regulatory Commission Mr. S. D. Ebneter, Regional Administrator Mr. D. S. Hood, Licensing Project Manager, NRR Mr. B. R. Bonser, Senior Resident Inspector, Vogtle 1

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UNITED STATES

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NUCLEAR REGULATORY COMMISSION

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Tog *er A. Newton stinghouse Owners Group 3;

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WESTIt!GHOUSE TOPICAL REPORTS WCAP-10271 SUPPLEMENT 2 A 534 6BJECT:

WCAP-10271 SUPPLEMENT 2 REVISION 1, "EYALUATION OF

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SURVEILLANCE FRE00ENCIES AND OUT OF SERVICE TIMES FOR TH

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23I ENGINEERED SAFETY FEATURES ACTUATION SYSTEH" 4'3 O'

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QT3M ij5 De'ar Mr. Newton:

We have completed our review of the subject topical reports submitted by the Westinghouse Owners Group by letters dated March 20, 1986 and May 12, 1987.

!U provides our Safety Evaluation Report (SER), which was prepared

=c2 52; g after reviewing the Technical Evaluation Report (TER attached to the SER) i We concur with Ef; developed under contract by Brookhaven National L6boratory.

the findings contained in the TER.

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'As noted in the enclosed SER, applicants for proposed Technical Specification 3!s

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changes for individual plants must:

Confirm the applicability of the generic analyses of WCAP-10271 Supplement 2

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and WCAP-10271 Supplement 2, Revision 1.

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Confirm that any increase in instrument drift due to the extended STIs is

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(For aeditional properly accounted for in the setpoint calculation nethodology.

gp i oated information on this issue, see letter from C. E. Rossi to F. F. Janecek, 3,

i l 3." 2 April 27, 1988.)

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c provides an acceptable format for proposed TS Changes baseo on lEEE i Our review WCAP-10271 Supplement 2 and WCAP-10271 Supplement 2, Revision 1.

7.! 3 of plant-specific changes will consider the applicabilities of the topical Jil; ;

reports to the specific plant.

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Lict.nsees and applicants are encouraged to propose changes to TS that are JI consistent with the guidance provided in the enclosures. Proposed license e.', j 3 amendments conforming to this guidance will be expeditiously reviewed by the NRC Project Manager for the facility. Proposed amendrents that oeviate from

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Please contact the 7*:i this guidance will recuire a longer, more detailed review.

jj]i Project Manager if you have ouestions on this catter.

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1 Fi.5 3 21989 Pursuant to 10 CFR 2.790, we have determined that the enclosed evaluation does not contain proprietary infomation. However, we will delay placing the evaluation in the Public Document Room for a period of ten (10) working days from the date of this letter to provide you with the opportunity to coment on the proprietary aspects only.

If you believe that any information in the enclosure is proprietary, please identify such information line by line and define the basis pursuant to the criteria of 10 CFR 2.790.

In accordance with procedures established in NUREG-0390 " Topical Reports Review Status," we request that the Westinghouse Owners Group publish accepted revisions of WCAP-10271 Supplement 2 and WCAP-10271 Supplement 2. Revision 1, both proprie-tary and non-proprietary, within three months of receipt of this letter. The accepted versions should (1) incorporate this letter and the enclosed Safety Evaluation Report including the Technical Evaluation Report, between the title

.I page and the abstract and (2) include an - A (designated accepted) following the report identification symbols.

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Should our acceptance criteria or regulations change so that our conclusions as to the acceptability of the reports are no longer valid, the Westinghouse Owners Group and/or the applicants referencing these topical reports will be expected to revise and resubmit their respective documentation, or submit justification for

,i the continued applicability of the topical reports without revision of their ji documentation.

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ENCLOSURE 1 SAFETY EVALUATION BY THE OFFICE OF HUCLEAR REACTOR REGULATION

" REvil'WTWBTTiiGHOUSE RUDhT WCAP-10271 SUFPLEMENT 2 AND WCAP-10271 5bEPLEMENT 7 13 ION 105'lVIIIIATIDN OF SUhiflI[lhCE FREGUEWCIll UT OF SERitt TTRIl W THE ENGINEERED,LAF @ lElluRES ACTUA,T,10L Si M !!

ie-1.0 EUMMARY The staff has reviewed the Westinghouse Topical Reports WCAP-10271, Supplement 2 and WCAP-10271 Supplement 2, Revision 1 " Evaluation of Surveillance Frecuencies and Out of Service Times for the Engineered Safety Features Actuation System",

supported by the Westinghouse Owners Group (WOG) for purposes of proposing extensions of surveillance test intervals (STIs) and test and maintenance allowed 38

[s outage times (A0Ts) for the Engineered Safety Features Actuation System (ESFAS).

Specifically, bases were provided for increasing the ST! for the analog channels or from 1 month to 3 months; no STI changes were requested for the combinational logic, or the master or slave relays.

It was also proposed that 1) the A0Ts for test for the analog channels be increased from 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for both solid state and relay systems, 2) the ACTS for test for all components be increased to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> in solid state systems, and

3) in relay systems, the A0Ts for test for the logic trains and master relays be increased to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and for the slave relays to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

Additionally, it was recuested that the A0T for maintenance for all components be extended to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for both relay and solid state systems. All components except the analog channels would be in bypass during the maintenance A0T, with an analog channel trippeo af ter spending 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> in bypass.

Finally, it was reouested that a staggered test requirement not be implemented for analog channels in the ESFAS and that this reouirement be removed for analog channels in the Reactor Protection System (RPS) (Ref. 1), many of which are common with ESFAS channels.

The staff has concluded that the analyses presented in WCAP-10271 Supplement 2 and WCAP-10271 Supplement 2, Revision 1, augmented by a Brookhaven National Laboratory (BHL) technical evaluation report (TER) are acceptable for resolving the STI and A0T extension issues, subject to any limitations and conditions presented herein.

Additionally the staff concludes that a staggered test strategy is no longer i

teouired for RPS analog channel testing, as originally stipulated in Ref. 1.

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2.0 BACKGROUND

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Iten. 4.5.3 of Generic Letter 83-26 (Ref. 2) requested that all licensees anc applicants review the existing RPS on-line functional test intervals requireo by Technical Specificatiens (TS). They are to ensure that current and proposed Th I

intervals (Ref.1) f or such testing are consistent with a goal of achieving high CD RPS availability. Extensions te RPS ST!s have been granted for Westinghouse th.

PWR plants.

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The ESFAS shares some comon instrumentation with the RPS. On the averagt, the re:

number of ESFAS analog channels sensing either process or nuclear parameters is tes

58. with 20 channels dedicated to the ESFAS and 38 channels common between ESFAS ass l

and RPS.

It is therefore worthwhile from an operational viewpoint to consicer pra extensions of STIs f or all ESFAS analog channels. Additionally, plant operational ef f ectiveress is enhanced by considering STI extensions for the ESFAS logic l

r cabinets and master ano slave relays. At the s ae time, consideration of extensice of test and maintenance A0Ts will allow more effective test ano maintenance This will reduce human error rates in these activities and the operations.

number of inacvertent actuations of engineered safety features.

Its due The 3.0 APPROACH exp The Westinghouse Owners Group (WOG) approached resolution of this issue to 1 generically. The unavailabilitics of the ESFAS signals were calculated by acce The Westinghouse /WOG (Ref.'s 3 and 4) for both relay ano solid state systems.

analyses show that the unavailabilities of the relay and solid state ESFAS Base ans' signals are of similar magnitude.

wou' The WOG originally evaluateo the impact of the proposeo STI and A0T changes on a te core damage frequency (CDF) and public health risk on the Hillstone Unit 3 plant.

the The staff and This plant has a solic state ESFAS with 2-out-of-4 (2/4) logic.

its contractor. Brookhaven National Laboratory (BNL). had a concern that Millstone Acci Unit 3 reight not fully bound the change in CDF due to the proposed ST! and A0T itp1 changes for all Westinghouse plants. Sonie plants have either a 2-out-of-3 (2/3) anal the logic or a corbination which may have higher unavailability than that associated with a 2/4 logic such as at Millstone Unit 3.

In response to this crmeern, abf)

Westinghouse perf ormed an analysis, documented as WCAP-102?1 SuppMent 2.

Revision 1, Acdendum 2 to determine the ef f eet on the change in tne Millstone 5,0 This resulted in 3 CDF of an assumed change of the ESFAS logic from 2/4 to 2/3.

a CDF increase for the 2/3 logic over the 2/4 logic of less than 1 percent of Baser the base case CDF for the solid state system. The staff concludes that the conc relay plants would exhibit similar relative CDF changes with respect to the Will repr(

1mpact of 2/3 vs. 2/4 logic.

analy llevit 4.0 NRC ACTION III f The staf f engaged the services of Brookhaven National Laboratory (BNL) to review This Adett the approach used and the an61yses performed in the Westinghouse reports.

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3 review was performed to determine the accouacy of the methods used to establish the technical bases for the proposed modifications of Sils and A0Ts for the g Westinghouse PWR ESFAS instrumentation and actuation relays, o bi The BHL review calculations yielded, for the proposed ESFAS ST!/A0T changes, a high CDF increase of 2.8% f or solid state plants, which is in good agreement with the 2.4% increase calculated by the WOG.

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!NL performed a variety of parametric CDF increase calculations.

Among the the j results was a relay plant CDF increase of 4% assuming concurrent slave relay Another BHL sensitivity study yielded a CDF increase of 5.7%.

testing.

5 is assuming a very conservative secuential testing scheme which is not used in g

ESF AS,

cer practice.

ational BNL also determined that use of Millstone Unit 3 as a reference plant may not l

fully bound the change in C0F due to the proposed STl/A0T changes because of its extensie 2/4 ESF AS logic, which yielded the 2.4% CCF increase. The 2/3 ESFAS logic WOG e

. Analysis. oiscussec earlier, yielded a 3.3% C0F increase.

The staff concludes. therefore that an overall upper bound for the CDF increase due to the proposed ST1/A0T changes is less than 61 for Westinghouse PWR plants.

The staf f also concludes that actual CDF increases for individual plants are expected to be substantially less than 65. The staff considers this CDF increase to be small compared to the range of uncertainty in the C0F analyses and therefore acceptable.

The Basec on the Westinghouse /WOG analyses ano the BNt. audit and sensitivity analyses, the staf f concludes that the proposed STI and A0T changes for the ESFAS BNL issued would have only a small and therefore acceptable impact on plant risk.

a technical evaluation report (Enclosure to this Safety Evaluation) presenting as on 3 plant the details and results of its reviews.

f and Accitionally the staf f concludes that a staggered test strategy need not be Millstc o A0T 1rplemented f or ESFAS analog channel testing and is no longer required for RPS 3 (E/F analog channel testing, as originally stipulated in Ref. 1.

This is based on the small relative contribution of the analog channels to RPS/ESFAS unavail-ociates ability, process parameter signal diversity, and normal operational test spacing.

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Based on a review of the BNL technical evaluation report (TER) the staff at of

, concludes that a 6% CDF increase due to the proposed STl/A0T extensions p

the the i represents an upper bound.

For realistic testing stratecies, tt e Ctf increase 1Willbesubstantiallylessthanthis. The staff therefore cone'.udes that the j analyses presented in WCAP-10271 Supplement 2 and WCAP-10271 Sulplement 2.

Revision 1, suomented by the TER, form an acceptable basis for increasing the STl for ESFAS analog channels f rom 1 month to 3 months.

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Additionally, the staff finds that 1) A0Ts for test for the analog channels o

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may be increased from 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for both solid state and relay systems, 2) the A0Ts for test for all components may be increased to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />

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. l in solid state systems, 3) The A0Ts for test for the logic trains and master relays may be increased to B hours and the A0T for the slave relays to 12

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-be extended _to-1240uts.._for both relay and solid state systems.rAdditTo'na y,

all components except the analog channers'Bre toWWbypWduring the main

• yance A0T, with an analog channel tripped after spending 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> in bypass 3,__

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Further, the staff will not require a staggered test strategy for ESFAS analog channel testing, and will no longer require a staggered test strategy for RPS analog channel testing, as stipulated in the staff SER of February 21, 1985 (Ref. 1). The rem';vai of the staggered test requirement is based on the small relative contributien of the analog channels to RPS/ESFAS unavailability, process parameter signal liversity, and normal operational test spacing, which is neither staggered nor seq;ential, but yields some of the benefits of staggereo testing.

j Table 1 lists plant-specific conditions that each licensee or applicant must meet to make any proposed STI or A0T changes fully acceptable. Table 2 surTnarizes the approved changes.

6.0 REFERENCES

1.

Safety Evaluation by the Office of Nuclear Reactor Regulation WCAP-10271,

" Evaluation of Surveillance Frequencies and Out of Service Times for the Reactor Protection Instrumentation System," February 21, 1985.

2.

Eisenhut, D.

G., NRC Letter to All Licensees of Operating Reactors, Applicants for Operating License, and Holders of Construction Pemits,

" Requested Actions Based on Generic jmplications of Salem ATWS Events,"

July 8, 1983.

3.

Andre, G. R., Howard, R. C., Jansen, R. L., and Leonelli, K., " Evaluation of Surveillance Frequencies and Out of Service Times for the Engineered Safety Features Actuation System," WCAP-10271, Supplement 2 February 1986.

4 Andre, G. R., Howard, R. C., Jansen, R.

L., and Leonelli, K., " Evaluation of Surveillance Frequencies and Out of Service Times for the Engineered Safety Features Actuation System," WCAP-10271, Supplement 2, Revision 1, March 1987.

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