ML20203B214

Safety Evaluation Supporting Amend 218 to License NPF-3

ML20203B214
Person / Time
Site:	Davis Besse
Issue date:	12/02/1997
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20203B189	List: ML20203B185 ML20203B214
References
NUDOCS 9712120373
Download: ML20203B214 (10)

Text

__-_ _ - - - - _

"%g n

i UNITED STATES j

[

j NUCLEAR REGULATORY COMMISSION "o

R WASHINGTON, D.C. 30666 0001 s

l S

%.....,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 218 TO FACillTY OPERATING LICENSE NO. NPF-3 TOLED0 EDISON COMPANY CENTER 10R SERVICE COMPANY AND THE CLEVELAND ELECTRIC ILLUMINATING COMPA81 DAVIS-BESSE NUCLEAR POWER STATION. UNIT 1 DOCKET NO 50-346

1.0 INTRODUCTION

By letters dated December 11, 1996 (as supplemented January 6, 1997),

January 30, 1997 (as supplemented September 15,1997), and April 18, 1997, Toledo Edison Company, Centerior Service Company, and The Cleveland Electric Illuminating Company, the licensees for the Davis-Besse Nuclear Power Station (DBNPS), Unit 1, requested NRC approval to implement amendments to its operating license NPF-3, by incorporating modifications to the Technical Specifications (TSs). The NRC staff reviewed taese submittals and by letter dated June 11, 1997, the staff requested additional information.

Da July 10, 1997, a conference call was held with the licensees to further discuss the d

staff request, and on August 21, 1997, a meeting was held with the licensees to discuss their responses.

By letter dated September 15, 1997, the licensees provided clarification to their original submittals.

In accordance with the licensees' eubmittals, the licensees have:

(a)

Proposed revisions to extend surveillance requirement intervals from 18 to 24 months based on the results of the DBNPS Instrument Drift Study; (b)

Proposed setpoint revisions based on the results of the DBNPS Instrument Drift Study and guidance in NUREG-1430, Revision 1,

" Standard Technical Specifications, Babcock and Wilcox Plants,"

dated April 1995; (c)

Proposed revisions to TS 2.2, " Limiting Safety System Settings,"

based on the results of revised Framatome Reactor Protection System string error and setpoint allowable value calculations and guidance in NUREG-1430, Revision 1; and (d)

Proposed administrative revisions supporting the preceding areas of revision.

9712120373 971202 1

PDR ADOCK 05000346 P

PDR

i 4

l 2 2.0 0LCKGROUND Improved reactor fuels allow licensees to consider an increase in the duration of tne fuel cycle for their facilities. The staff has reviewed requests for individual plants to modify TS surveillance intervals to be compatible with a 24-month fuel cycle. The staff issued Generic Letter (GL) 91-04, " Changes in Technical Specification Surveillance Intervals to Accommodate a 24-Month Fuel Cycle," on April 2,1991, to provide generic guidance to licensees for preparing such license amendment requests.

TSs that specify an IB-month surveillance interval could be changed to state that these surveillances are to be performed once per refueling interval.

The notation for surveillance intervals would then be changed to include the definition of a " Refueling Interval" with the existing "R" notation for surveillances that are generally performed during a refueling outage.

The frequency for the interval indicated by this notation would also be changed from 18 n,nths to "at least once every 24 months." The TS provision to extend surveillances by 25 percent of the specified interval would extend the time limit for completing these surveillances from the existing limit of 22.5 months to a maximum of 30 months.

Licensees must address instrument drift when proposing an increase in the surveillance interval for calibrating instruments that perform safety funt.tions whicn includes providing the capability for safe shutdown. The effect of the increased calibration interval on instrument errors must be addressed because instrument errors caused by drift were considered when determining safety system setpoints based on design basis accident analyses.

In accordance with GL 91-04, to provide an acceptable basis for increasing the calibraticn interval for instruments that are used to perforn safety functions, the licensees should:

(1)

Confirm that instrument drift as determined by as-found and as-left calibration data from surveillance and maintenance records has not, except on rare occasions, exceeded acceptable limits for a calibration interval; (2)

Confirm that the values of drift for each instrument type (make, model number, and raage) and application have been determined with a high probability and a high degree of confidence.

Provide a summary of the methodology and assumptions used to determine the rate of instrument drift with time based upon historical plant calibration data; (3)

Confirm that the magnitude of instrument drift has been determined with a high probability and a high degree of confidence for a bounding calibration interval of 30 months for each instrument type (make, model number, and range) and application that pe'rforms a safety function.

Provide a list of the channels by TS section that identifies these instrument applications;

~

. - - - - _ - - = _.

, (4)

Confirm that a comparison of the projected instrument drift errors ha< been made with the values of Mrift used ir the setpoint analysis.

If this results in revised setpoints to accomodate larger drift errors, provide proposed TS changes to update trip setpoints.

If the drift errnrs result in a revised safety analysis to support existing setpoints, provide a sumary of the updated analysis conclusions to confirm that safety limits and safety analysis assumptions are not exceeded; (5)

Confirm that the projected instrument errors caused by drift are acceptable for control of plant parameters to effect a safe shutdown with the associated instrumentation; g6)

Confirm that all conditions and assumptions of the setpoint and safety analyses have been checked and are appropriately reflected in the acceptance criteria of plant surveillance procedures for channel checks, channel functional tests, and channel calibrations; (7)

Provide a sumary description of the program for monitoring and assessing the effects of increased calibration surveillance intervals on instrument drift and its effect on safety; and (8)

Maintain a program to monitor calibration results and the effect on instrument drif t that will accompany the increase in calibration intervals.

For other 18-month surveillances, licensees should evaluate the effect on safety of the change in surveillance intervals to accomodate a 24-month fuel cycle. This evaluation should support a conclusion that the effect on safety is small.

In addition, licensees should confirm that historical maintenance and surveillance data do not invalidate this conclusion.

Licensees should confirm that the performance of surveillance at the bounding surveillance interval limit provided to accomodate a 24-month fuel cycle would not invalidate any assumption in the plant licensing basis.

In consideration of these confirmations, the licensees need not quantify the effect of the change in surveillance intervals on the availability of individual systems or components.

3.0 EVALUATION The licensees have proposed the following changes to the TSs:

Proposed Chance TS Table 1.2, " Frequency Notation," change the notation "R" to "E" to define a frequency of "at least once per 18 months," and redefine "R" to "at least once per 24 months." Also, the feltnote with an asterisk has been revised to add that 24 months is defined to be 730 days.

l l

\\

o

=.

, Evaluation The proposed change to TS Table 1.2 is an administrative change only consistent with the proposed revised surveillance interval, and is, therefore, acceptable.

Proposed Chance This license amendment request will extend surveillance testing intervals for selected instrumentation from every 18 months to each refueling interval (24-month fuel cycle plus 25% allowable tolerance).

The licensees proposed replacing "at least once per 18 months" with "at least once each REFUELING INTERVAL" for t' a TSs described below:

(a)

TS Table 4.3-1, " Reactor Protection System (RPS) Instrumentation Surveillance P.cquirements," Functional Units 3, 4 (a change to Notation 7), 5, 6, 7, 14, and 15; (b)

TS Table 4.3 2, " Safety Features Actuation System (SFAS)

Instrumentation Surveillance Requirements," functional Units Id, le, Sa, 5b, and 3 (manual actuation switch only);

(c)

TS Table 4.3-6, " Remote Shutdown Monitoring (RSM) Instrumentation Surveillance Requirements," functional Units 2 through 6; (d)

TS Tame 4.3-10, " Post Accident Monitoring (FAM) Instrumentation Surveti ance Requirements," Functional Units 1 through 5, 6a,10 l

through 13, 15 through 17, 2nd 19; (e)

TS Table 4.3-11

" Steam and Feedwater Rupture Coi. trol System (SFRCS)

Instrumentation Surveillance Requirements," Functional Units Ib and 2;

(f)

TS Section 4.4.3, " Safety Valves and Pilot Operated Relief Valve -

Operating," CHANNEL CALIBRATION surveillance interval for pressurizer PORV; (g)

TS Section 4.4.6.1.b, " Reactor Coolant System Leakage," CHAdNEL CALIBRATION surveillance interval for containment sump level and flow monitoring system; (h)

TS Sections 4.7.1.2.1.d, 4.7.1.2.1.e, and 4.7.1.2.2, " Auxiliary Feedwater System," CHANNEL CALIBRATION surveillance interval for Auxiliary Feedwater Pump (AFP) Turbine, Steam Generator Level Control System, AFP Suction Pressure Interlock, and AFP Turbine Inlet Steam Pressure Interlock; (i)

TS Section 4.5.1.d, " Emergency Core Cooling System," verification that each core flood tank isolation valve opens automatically and is I

s i interlocked against closing whenever the RCS pressure exceeds 800 psig; and (j)

TS Section 4.5.2.d, " Emergency Core Cooling System," verification that the interlocks for the Decay Heat Isolation Valves, pressurizer heater and borated water storage tank (BWST) low-low level interlock trip perform their function.

(Note:

The TS text change to

" REFUELING INTERVAL" was addrested in Amendment No. 216, issued simultaneously with this amendment.)

Evalualha The proposed changes allow the continued application of TS 4.0.2.

This TS permits surveillance intervals iLO be increased up to 25% on a non-routine basis (30 months) in accordance. with GL 91-04.

A paragraph was added (Amendment 213, dated February 10,1997) to TS Bases 4.0.2, consistent with GL 91-04, that ensures that surveillances are performed in an operational mode consistent with safe plant operation.

This TS Bases section already included clarification that the allowable tolerance not be used es a convenience to repeatedly schedule the performance of surveillances at the maximum time limit permitted by the TS.

The licensees performed a safety assessment for the proposed changes to the surveillance test intetvals in accordance with the GL 91-04 guidance stated above.

This assessment entailed reviewing the historical maintenance and surveillance test data at the bot.nding surveillance interval limit, performing an evaluation to ensure that a 24-month surveillance test interval would not invalidate any assumption in the plant .ensing bases, and the determination that the effect on safety of the surveillance intervai extension is small.

Only the period since 1985 was reviewed. However, this is most representative of current plant operating conditions since many changes to DBNPS occurred after the loss of feedwater event in 1985.

This period includes five refueling outages and four operating cycles of test data and results.

The licensees performed analyses of drift for all affected instrument loops in order to establish the effect of a 30-month (24 months plus 25% allowable tr,ierance) calibration frequency on instrument performance using the in-house gvedure, " Drift Data Analysis Methodology and Assumptions," Revision 1, datad May 8, 1996. The analyses were performed to verify that the surveillance interval extensions have an insignificant effect on plant safety and would not invalidate any assumptions in the plant licensing basis.

Statistically based drift values were deterrined for the instruments involved.

In the evaluation of drift data time dependency and the determination of a projected 95/95 confidrnce interval for expected 30-month drift, the licensees used one of the following three approaches:

(a)

Drift is time independent, and the 95/95 confidence interval calculated from historical as-found/as-left data applies to a 30-month calibration interval;

~

O

! 1 (b)

Drift is time dependent, and each individual drift data point (calculated for calibration intervals less than 30 months) is extrapolated to 30 months using a linear method; and (c)

Drift is time dependent, and each individual drift data point is extrapolated to 30 months by using the square root method.

If this method is used, a justification is provided.

e The above drift evalection approaches are consistent with GL 91-04 and are, therefore, acceptable to the staff.

In GL 91-04, the staff identified the issues discussed in the background settim. of this evaluation pertaining to increasing the interval of instrument surveillance and identified specific actions that licensees should take to address these issues. The staff has evaluated the licensees' submittals to verify that the licensees have addressed these issues and provided an acceptable basis for increasing the calibration interval for instrumenti that are used to perform safety functions.

Based on the evaluation as described above, the staff concludes that the licensees have confirmed that safety limits and safety analysis assumptions will not be exceeded after the worst case drift is considered for the instruments indicated above for which surveillance intervals will be extended to 24 months, Proposed Chanag The licensees proposed the following setpoint changes required as a result of the DBNPS Instrument Drift Study and based on NUREG-1430 Revision 1:

(a)

TS Table 3.3-12, "SFRCS instrumentation Trip Setpoints," Functional Unit 2, aliceable value has been changed from 215.6" to 216.9" and the trip setpoint has been deleted.

In addition, TS 3.3.2.2 has been modif!ed to be consistent with this change; (b)

TS Table 3.3-4, "SFAS Instrumentation Trip Setpoints," Functional Unit d, allowable value has been changed from 2 1615.75 psig to 2 1576.2 psig and the trip setpoint has been deleted; (c)

TS Table 3.3-4, "SFAS Instrumentation Trip Setpoints," Functional Unit e, allowable value has been changed from 2 415.75 psig to 2 441.42 psig and the trip setpoint has been deleted; (d)

TS Table 3.3-4, "SFAS Instrumentation Trip Setpoints,"

Functional Unit a, for Interlock channels (Decay Heat Isolation Valve and Pressurizer Heater), allowable value has been changed from

< 443 psig to < 328 psig and the trip setpoint has been deleted; and (e)

TS 3.3.2.1, "SFAS Instrumentation," has been modified consistent with (b), (c), and (d) above, t

1 0'

y o.

. Evaluation In their submittal, the licensees stated that their calculations to revise the allowable value (AV) of functional units to support the surveillance test interval extension are based on the methodology described in Framatome documents 32-1172392-02, " Reactor Protection System String Error Calculations," and 32-1257719-02, " Davis-Besse Unit 1-RPS Allowable Values 1

Calculations." This methodology is consistent with the guidance of Regulatory Guide (RG) 1.105, Revision 2, which endorses Instrument Society of America (ISA) S67.04-1982, regarding accounting for uncertainties in setpoint calculations, except for Section 4.3.l(2)(a), which states that the accuracy of test equipment for measuring setpoints shall be included in the allowances between AV and the trip setpoints. The licensees determined that test instrument uncertainty is sufficiently small such that it would not affect the A'! significantly.

Based on this, the staff finds the licensees' setpoint methodology acceptable.

Proposed Chanae The licensees proposed the following changes to TS Section 2.2, " Limiting Safety System Settings," based on the results of the revised Framatome RPS string error and setpoint allowable value calculations and the guidance of NUREG-1430, Revision 1:

4 (a)

TS Table 2.2.1, "RPS Instrumentation Trip Setpoints," Functional Unit 2, High Flux, changed allowable value from < 104.9% to 5 1%.1%;

(b)

TS Table 2.2.1, "RPS _ Instrumentation Trip Setroints," Functional Unit 5, RC low pressure, changed allowable value from > 1900 psig to

t 1900 psig; (c)

TS Table 2.2.1, "RPS Instrumentation Trip Setpoints," Functional Unit 6, RC high pressure, changed allowable value from < 2355 psig to s 2355 psig; and (d)

Deleted the column for trip setpoint.

Evaluation These TS changes are based on an acceptable setpoint methodology as discussed in the previous section of this evaluation and are consistent with NUREG-1430, Revision 1.

Therefore, the staff finds them acceptable.

Administrative Chanaes The licensees proposed the following administrative changes to the TSs:

(a)

All surveillances for instruments in TS Tables 4.3.1, 4.3.2, 4.3.3, 4.3.10, and 4.3.11, which were previously identified as "R" but were

l ss D not changed to the new refueling interval, have been designated as "E" to indicate that the surveillance interval for these instruments remains at 18 month:,;

(b)

TS Section 2.2.1 and its associated ACTION statement have been revised to replace " trip setpoint" with " allowable value";

(c)

TS Sections 4.5.2.d.l.a and 4.5.2.d.l.b have been revised to replace

" trip setpoint" with " allowable value." Also, the allowable value as given in TS Table 3.3-4 was included in place of the trip setpoint value; (d)

TS Sections 4.3.1.1.2, 4.3.1.1.3, 4.3.2.1.2, 4.3.2.1.3, 4.3.2.2.2, 4.3.2.2.3, and 4.3.3.5.2; Notation 7 in TS Table 4.3-1; and Notation 1 in TS Table 4.3-2 were changed to replace "18 months" with

" Refueling Interval";

(e)

TS Section 3.3.2.1 ACTION "a" nas been revised to state, "... trip setpoint adjusted consistent with Table 3.3.4" instead of

... consistent with the trip setpoint value";

(f)

TS Table 3.3-3 Notation "**" has been revised from 600 psig to 660 psig. ACTIONS "13a," "13b," and "14" have been revised from < 438 psig to < 328 psig, and have been modified to clarify that

" indicated" reactor coolant pressure is the referenced parameter; (g)

A footnote to TS Tables 3.3-4 and 2.2-1 has been added to include the allowable value for CHANNEL FUNCTIONAL TEST; (h)

TS Section 3.3.2.2 ACTION "a" has been revised to state, "... trip setpoint adjusted consistent with Table 3.3-12" instead of

... consistent with the trip setpoint value";

(i)

TS Table 4.3-10, Instrument 6, " Containment Vessel Post-Accident Radiation," has been revised to list two separate instruments, (6a) Containment High Range Radiation and (6b) Containment Wide

• Range Noble Gas. The containment high range radiation monitor will have the surveillance frequency of 24 months while the containment wide range noble gas monitor will continue to be on an 18-month surveillance interval; (j)

TS Basis Sections 3/4.3.1, 3/4.3.2, 3/4.5.2, and 3/4.5.3 have been revised to include the bases for the changes in surveillance frequency and instrument setpoint/ allowable value discussed previously in this evaluation; and (k)

TS Basis Section 2.2.1 has been revised to change trip setpoints to allowable values and add the new allowable value for high flux.

l

,? :

, Evaluation All of the above changes are administrative in nature as they reflect TS changes for new setpoint/ allowable values, action statements, and surveillance intervals consistent with the 24-month refueling outage surveillance interval as discussed above. Therefore, the changes are acceptable.

Evaluation of Radioloalcal Consecuences TS Amendment No. 181 was issued to DBNPS on November 19, 1993.

This change allowed the licensees to utilize fuel with up to 5% enrichment, and extended fuel assembly average discharge burnup to 60,000 megawatt days per metric ton of uranium (MWD /HTV), so that extended fuel cycles would be possible. This license amendment request to revise certain TS surveillance requirements for conversion to a 24-month fuel cycle will not exceed the allowabla 60,000 MWD /MTU fuel burnup limit.

The licensees identified in the request that three design basis accidents impacted by the proposed changes are the 0.04 square foot small break loss-of-coolant accident, the letdown line break accident, and the steam generator tube rupture accident.

The licensees concluded, and the staff agrees, that these three accidents do not involve any core damage and that only the radiological consequences resulting from the letdown line break accident is affected by the proposed changes. The licensees reanalyzed the radiological consequences resulting from the letdown line break accident and showed that the recalculated doses are higher than those previously reported but they are still within a small fraction of dose criteria specified in 10 CFR Part 100.

The staff reviewed the radiological consequence analysis summary submitted by the licensees for the letdown line break accident and finds it to be acceptable.

Concludina Remarks Based on its review, the staff concludes that the proposed DBNPS TS modifications to extend surveillance intervals for certain safety-related instrumentation components are consistent with the guidance in GL 91-04 and NUREG-1430, Revision 1, in that the licensees have demonstrated that the effect on safety of extending the surveillance interval to 24 months is negligible and the system will continue to perform within assumed limits during the longer surveillance interval. The staff finds that the setpoint methodology, drift analysis and changes proposed for the TS AVs and setpoints are in accordance with the guidance of RG 1.105 and are consistent with design basis accident analyses. Therefore, the staff finds the proposed TS modifications for a 24-month surveillance interval to be acceptable.

4.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Ohio State official was notified of the proposed issuance of the amendment. The State official had no coments.

l

5.0 ENVIRONMENTAL CONSIDERATION

This amendment changes a requirement with respect to in:ta11ation or use of a facility component located within the restricted area as defined in 10 CFR The staff has determined that Part 20 or changes a surveillance requirement.

the amendment involves no significant increase in the amounts, and no significant change in the types, of cny effluent that may be released offsite, and that there is no significant increase in individual or cumulative The Commission has previously issued occupational radiation exposure.

proposed findings that the amendment involves no significant hazards consideration, and there has been no public comment on such findings (62 FR 2194, 62 FR 11498, 62 FR 30645). The supplemental information submitted by the licensees did not affect the proposed findings. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

6.0 CONCLUSION

The staff has concicded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner; (2) such activities will be conducted in compliance with the Commission's regulations; and (3) the issuance of this amendment will not be inimical to the common defense and security or to the health ar.d safety of the public.

Principal Contributor:

H. Garg Date: December 2, 1997

_