ML20085G437

Safety Evaluation Supporting Amend 64 to License NPF-30

ML20085G437
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Site:	Callaway
Issue date:	10/09/1991
From:	Office of Nuclear Reactor Regulation
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c,, v j SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. M 10,,F Atlll1Y OPERATING _ LICENSE NO. NPF-30 UNION ELECTRIC C0FpANY EALLAWAY PLXRT. UNIT'T TEET NO. 5TN 50-483

1.0 INTRODUCTION

Dy letter dated March 19, 1991, the Union Electric Company (the licensee) requested changes to the Technical Specifications (Appendix A to f acility Operating License No. NpF-30) for the Callaway plant, Unit _1.

The proposed changes would be in accordance with the staf f's safety evaluations (SEs) and supplemental safety evaluations (SSEs) described below to modify the engineered safety features actuation systems (ESFAS) and reactor trip system (R15) instrumentation surveillance and testing.

2.0 BACKGROUND

in response to growing concerns over the impact of current testing and main-tenance requirements on plant operation, particularly as related to instrumen-tauon systems the Westinghouse Owners Group (WOG) initiated a program to develop a justification to be used to revise generic ano plant-specific instrumentation technical specificationc.

Operating plents have experienced inadvertent reactor trips and safeguards actuations during performance of instrumentatior, surveillances, causing unnecessary transients and challenges to saf ety systems.

Significant time end eff ort on the part of plant operating staff s have been devoted to performir.g reviewing, documenting, aled tiacking the various surveillance activities.

In response to this concern, the WOG submitted WCAP-10271, " Evaluation of Surveillance Frequencies and Out-of-Service Times for the Reactor protection Instrumentation System," to the NRC on Fcbruary 3,1983.

In July 1983, the NRC requested additional information f rom the WOG (letter f rom C.O. Thomas to J. J. Sheppard dated July 28, 1963). The WOG responded in October 1983 with Supplement 1 to WCAP-10271, which contained the additional information requested. Specifically, Supplement 1 demonstrated the applicability of the Justificattoa contained in WCAP-10271 to the Reactor Trip System (RTS) for two, three, and tot.r loop plants with either relaj or solid state logic.

Additionally, this supplement extended the evaluation to topics not addressed in the original Westinghouse report, such as the interdependence of surveillance intervals and hardware f ailure rates.

(1) an increase in The NRC issued an SE in February)19GS that allowed for:from nonthly to quarterly; (2) an surveillance test intervals (STI in the time allowed for an inoperable channel to be placed in the tripped 1

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, condition from 1 to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />; (3) an increase in the allowable out of service tine for surveillance and maintenance; and (4) testing in bypass for analog channels of the RTS.

The SE also required quarterly testing to be conducted on a staggered basis.

Subsequently, the licensee submitted on October 16, 1985, a request for a revision to the Callaway Technical Specifications (TSS) in accordance with the SE cited above.

These were approved in License Amendment No.17 issued on September 8,1986.

This license apenament revised TS Table 3.3-1, "RTS Instrunentation," and TS Table 4.3-1, "RTS Instrumntation Surveillance Requirements," to increase the allowable out-of-service tine (A0T) for the RTS analog channels and to extend the surveillance test interval (STI) for the analog channel operational tests (ACOTs). These changes were in accordance with WCAP-10271 and WCAp-10271, Supplenent 1, as approved by the NRC staf f in its SE dated February 21, 1985.

Specifically, the revisions approved by the NRC in License Anendment No.17 allowed the licensee, f or the RTS analog channels only, to:

(1) perform STis quarterly on a staggered basis; (2) tale 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to place an inoperable channel in a tripped mode; (3) increase A0Ts for test up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and for maintenance up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />; and (4) do testing in bypass.

On March 20, 1986, the WOG submitted WCAP-10271, Supplement 2. " Evaluation of Surveillance Frequencies and Out of Service Times for the Engineered Safety features Actuation Systems." On May 12, 1987, the WOG submitted WCAP-10271, Supplenent 2, Revision 1.

After reviewing these additional Westinghouse reports, the NRC issued another SE on February 22, 1989 (letter f rom C.E. Rossi to R. A. Newton).

This SE extended the staff's approval of the same changes that it had previously approved for the RTS analog channels only to the ESFAS analog channels.

Staggered testing sas not required for ESFAS analog channels and this requirenwnt was removed from the RTS analog channels.

This latest SE also concluded that 4-hour test and 12-hour maintenance A0Ts ate acceptable f or ESFAS automatic actuation logic and actuation relays.

On April 30, 1990, the NRC issued an SSE for WCAp-10271, Supplement 2, Revision 1 (letter from C.E. Rossi to G.T. Goering). This SSE approved A0T and STI exten', ions for the ESFAS functions which are non-Standard Technical Specifications and also approved 4-hour test and 12-hour maintenance A01s for the RTS actuation logic. No changes were approved for the test and nelntenance A0Ts for the reactor trip breakers.

The reduction in testing associated with these changes is expected to result in fewer inadvertent reactor trips and less frequent spurious actuations of ESFAS components. As stated in the staff's SEs and SSEs cited above, the increase of A0Ts and STis for the ESFAS analog channels ond A0Ts for tne actuation logic and relays will result in a slight increase in the probability of core damage accidents. The staf f concluded that an overall conservative upper bound for the core damage frequency (CDF) increase due to the proposed STI/A0T changes is slightly less than 6 percent for Westinghouse pWR plants.

The staff also concluded that actual CDF increases for individual plants are expected to be substantially less than 6 percent.

o 3-The staf f considered this CDF increase to be small compared to the range of uncertainty in the CDF analyses and therefore acceptable.

Based on the WOG analyses and subsequent staff review, the staff concluded that the proposed STl and A0T changes for the ESFa? and Ris would have only a small and, therefore, deceptable impact on overall p? ant risk.

In both its SE dated February 22, 1989, and its SSE dated April 30, 1990, the NRC encouraged licensees to propose changes to their technical specifications which are consistent with the guidance provided by the staf f.

An acceptable fonnat for proposing technical specification changes based on the Westinghouse reports cited above was provided to the WOG in the SE dated February 22, 1989.

In order for the staff to find the licensee's submittals acceptable, the licensees must:

1.

Confirm the applicability of the generic analyses of WCAP-10271, Supplement 2, and WCAp-10271, Supplement 2, Revision 1; and 2.

Confinn that any increase in instrument drif t due to the extended ST!s is properly accounted for in the setpoint calculation methodology. (Licensees were to use the letter from C. E. Rossi to R. F. Janecek, dated April 27, 1988, for guidance on this issue.)

3.0 EVALUATION As discussed above, in order for the generic technical specification changes to be acceptable for specific plants, licensees nost address two specific issues.

The licensee must first confirm the applicability of the generic analyses of WCAp-10271, Supplenent 2, and WCAP-10271, Supplement 2, Revision 1, to its facility.

In its letter of March 19, 1991, the licensee stated that the methodology of WCAP-10271 and its supplements were applied to specific RTS and ESFAS functions implenented in the Callaway facility via the Westinghouse Solid State Protection System (SSPS).

The licensee performed a review to determine that the functions used in the generic analysis and the use of the SSPS to perfurm ESFAS functions, as described in the generic analysis, are applicable to the Callaway design.

Based on its review, the licensee concluded that the Westinghouse reports cited above are applicable to the Callaway design.

The second issue that needed to be addressed was the staff's concern regarding instrument drif t over the extended Sils.

In its submittal, the licensee stated that instrument drif t data f rom previous analog channel operational tests had been examined and concluded that a review of the data confirmed that the setpoint drift which could be expected under the extended ST!s remains within the existing allowance in the instrument setpoint calculation.

In addition, the licensee committed to review "as found" and "as left" data for those channels with increased STis for a 1-year period to verify that setpoint drift remains within the existing allowance in the instrument setpoint calcu'aticn.

The specific changes proposed by the licensee to the Callaway Technical Specifications include t1e following:

I

o l 1.

Tabhs 3.3-1 and 4.3-1, functional Unit 14 Notes 1 and 15 are deleted f rom Tables 3.3-1 and 4.3-1, respectively, for f unctional Unit 14. These notes deal with channels that are shared by both the RTS and ESFAS; however, functional Unit 14 of Tables 3.3 1 and 4.31 (RCP Undervoltage Reactor Trip) is unrelated to functional Units 6.f and 8 of Tables 3.3-3 and 4.3-2 (Loss of Offsite Power-Start Turbine Driven Auxiliary Feedwater Pump and Loss of Power). The fomer deals with 13.8 kv power supplies (buses PA01 and PA02) whervas the latter deal with 4.16 kv power sup)1ies (buses NB01 and NB02). These notes were inadvertently added to unctional Unit 14 via References 1 r

and 2.

(Refer to Section 7.0 of this SE.) It is noted that Table 3.6-9 of Reference 3 analyzed for unavailability effects on the start

.of the auxiliary feedwater pump associated with RCP bus undervoltage and that this functional relationship is included in the Westinghouse Standard Technical Specifications (STS).

flowever, this design does not apply to Callaway.

2.

Table 3.3-1 Functional Units 17 and 20 Per Reference 4 and Apaendix D to Reference 3, test and maintenance A0Ts for SSPS logic ca)inets are extended. New Action Statement 31 provides for these test and maintenance A0T extensions. The extended test A0T for the RTS logic surveillance includes bypassing the associatd reactor trip breaker (i.e., racking in the bypass breaker) for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

Since Functional Unit 17 is i glemented in the SSPS logic given that the action statement changes on page D-7 of Reference 3 were approved in Reference 4, this new Action Statement 31 applies to both the RTS safety injection input from engineered safety features (ESF) as well as the automatic trip and interlock logic. Current Action Statement 9 will apply only to the reactor trip breakers, functional Unit 19, and has been clarified as such.

3.

Tables 3.3-1 and 4.3-1 With the approval of the ESFAS changes discussed in References 3,4 and 5, the A0Ts and STls for RTS and ESFAS analog channels are now the same.

Note 1 of Table 3.3-1 and Note 15 of Table 4.3-1 have been revised appropriately.

4.

Table 4.3-1 Per References 3 and 5, staggered testing is no longer required for RTS analog channels.

Note 14 has been deleted appropriately.

5.

Table 3.3-3 Per Reference 5 which approved changes for ESFAS functions in the Westinghouse STS, as given in Appendix Al of Reference 3, (i.e., Callaway functional Units 1.c,1.d, 2.c, and 3.b.3) and Reference 4 which approved changes for non-STS ESFAS functions, as Diven in Appendix A2 of Reference 3, (i.e., Callaway Functional Units 1.e, 4.c 4.d 4.e, 5.b, and 6.d), A0Ts

t

-S-for ESTAS analog channels are exter ded. Revised Action Statement 16 provides for an extended A0T (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 surveillance testing of analog channels of Functional Units 2.c and 3.b.3). New Action Statement 33 allows 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to piece an inoperable channel in the tripped mode as well as an extended A0T (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 surveillance testing of analog channels of Functional Units 1.c, 1.d.1.e. 4.c. 4.d. 4.e 5 b, and 6.d (see item 11 below). New Action Statenent 32 provides similar A0T extensions for functional Unit 7.b, as further discussed in item 12 below. Current Action Statenent 19 remains applicable to Functional Units 6.g. 8.a and 8.b which are associatedwiththeBalanceof-PlantESFAS(BOP-ESFAS)andtheLoad Shedding and Emergency Load Sequencing (LSELS) systems. These systems were not included in the Reference 3 analyses.

(This is discussed in item 1.a on Page 9, Attachnent 1, of the licensee's letter dated March 19, 1991.)

6.

Table 3.3 3 Per Reference S. A0Ts for the ESTAS automatic actuation logic and actuation relays _in the SSPS are extended. Revised Action Statenent 14 provides for these test and maintenance A0T extensions for Functional Units 1.b.,

2.b 3.a.2,intenance A0T extensions for Functional Units 4.b and 6.b.3.b.2, and 7.a. Ne test and ma Current Action Statement 21 remains applicable to functional Unit 6.c which is associated with the BOP ESFAS not included in the Reference 3 analyses.

(This is also discussed in Item 1.a on Page 9, Attachment 1, of the licensee's letter dated March 19,1991.) Revised Action Statenent 27, r

applicable only to Functional Unit 5.a, also provides for the above test and maintenance A0T extensions. The requirement to be in at least HOT STANDBY within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> in revised Action Statements-14 and 27 as well as in new Action Stateaents 31 and 34 reflects the approved 12-hour maintenance A0T.

7.

Table 3.3-3, functional Unit 6 9 The du-energiration of one train of BOP-ESFAS actuation logic and actuation relays will render two of the four main feedwater pump pressure switches inoperable. This situation impacts both Functional Units 6.c and 6.g.

Action Statewnt 21 for Functional Unit 6.c provides for. operation with an A0T with one B0P-ESTAS logic train de-energized. However, operation is not permitted under current Action Statement 19 for Functional Unit 6 9 with two pressurc switches inoperable. As such, Specification 3.0.3 would be entered.

Therefore, for clarification, a new footnote indicated by 3 asterisks has been added which states that Action Statement 21 applies to both functional Units 6.c and 6.g in this situation

-(1.e., it applies to both the B0P-ESFAS logic and to the AFW start on trip of both main feedwater pumps if one train of BOP-ESFAS logic is de-energized).

8.

Table 3.3-3, Action Statenent 22 Action Statement 22 is clarified regarding the :;equence of actions in a manner similar to Action Statements 1,10, and 18.

~. - -. - - - -. -..

a l 9.

Table 3.3-3, Action Statement 35 Action Statement 35 (previously 27(a) in Reference 6) is grammatically corrected such that tie plurality of the object of a prepositional phrase matches that of the subject being described (i.e., "... channels in the affected protection sets...."). This is consistent with Action Staternents 7 and 36 (previously 27(b) in Reference f, and represents the changes as requested in Reference 7.

10. Table 4.3-2 As discussed in the background for Item 5 above, quarterly STis for analog channel operational testing (ACOT) were aporoved in References 3, 4 and S.

Therefore, the 5T1 for Functional Units 1.c,1.d 1.e, 2.c, 3.b.3, 4.c, 4.d. 4.e. 5.b, 6.d and 7.b (see Item 11 below), and t

11.a is changed from monthly to quarter y.

11. Tables 3.3-3 and 4.3-2, Functional Units 6.d and 7.b A0T extensions for surveillance testing and STI extensions for the ACOT of analog channels of Functional Unit 7 b, RWST Level Low-Low Coincident with Safety Injection (for Automatic Switchover to Containment Sump),

were not approved as a part of the generic Technical Specification Optimization Program (TOP) discussed in References 3, 4 and 5 nor did the generic program consider the effects of the Environmental Allowance Modifier (EAM) and Trip Time Delay (TTO) added to the steam generator level analog channel circuitry as discussed in References 6, 7 and 8.

A separate evaluation was performed which demonstrated that the unavailability and risk results presented in Reference 3 for the A0T and STI increases are indicative of, or conservative with respect to, the results expected for increasing the A0T and STI of the analog channels of Functional Unit 7.b. Refertnce 3 demonstrated that the effects of the analog channel changes have a minimal inpact on overall reliability and risk, based en the small relative contribution of analog channels in general to RTS/ESFAS unavailability. The unavailability of the RWST low-lod-1 (2 out of 4) signal would be expected to be on the saine order of magnitude as that for the OT-Delta T, OP-Delta T, and High Pressurizer Pressure reactor trip signals due to similarities in logic coincidence and circuit cards in the inst Table 4.4-3 of WCAP-10271-P-A establishes this value as 10~gunent loops.

This apprcximate unavailability for the RWST low-low-1 signal is generally an order of magnitude less than the Case 1 safety injection signal unavailabilities given on Table 3.6-6 of Reference 3.

Therefore, this separate evaluation concludes that the A0T and STI extensions for functional Unit 7.b should be acceptable since the safety injection signal (515) unavailability, increases to which were accepted by the staf f, would be expected to dominate the automatic switchover signal unavailability (i.e., slight increases in RWST level signal unavailability would be outweighed by the SIS unavailability whose coincidence is necessary for automatic switchover).

1 1

f In addition to the generic conclusions regarding the relative insignificance of the analog channels to ESFAS unavailability, the A0T and STI extensions For Functional Unit 6.d are supported by the following considerations:

1)

As discussed in Section 3.4.2 of WCAP-11083, submitted via Reference 8 for the EAM/TTD modificatio', and as described in Section !.5 of the RTD Bypass Licensing Report attached to Reference 9 (i.e., the Delta-T input to TTD), the mean time between failure (ItTBF) values fer the 7300 printed circuit cards used in these nodifications are suf ficiently high that the reliability of the protection systems it, net degraded.

ii) Although the TTD timer modules are unique to Functional Unit 6.d (see Functional Unit 13.c of Table 3.3-1), they are disabled above 20% rated thertui power as discussed in Reference 8.

iii) Extended A0Ts a'id STls were approved f or RTS Functional Unit 13 of Tables 3.3-1 and 4.3-1 Steam Generator Water Level Low-low in References 0 and 6. Since these level channels are conmon to both the RTS and ESFAS, consistent A0Ts and STis are desirable. (This is discussed in item 2.d on Page 12, Attachment 1, of the licensee's letterdatedMarch19,199'.)

12. Table 3.3-3, Functional Unit 7.b New Action Stdesnent 32 allows for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to place an inoperable channel in the tripped mode as well as an extended ACT (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 />) fo' surveillance test W or analog channels of Functional Unit 7.b, if thechannelisinop9rabieforanyreasonotherthansurynillancetesting.

The inoperable channel raust be restcred to OPERABLE status witnin 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or the plant must be shut down, if the channel is inoperable because it is being tested, the channel may be tripped for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> fcir the surveillance testing. Current Action Statement 16 does not apply to Functional Unit 7.b since testing or operation in bypass, other than as discussed in item 2.c, on Page 11 Attachmer.t 1, of the licensee's letter dated March 19, 1991, is r.ot applicable to the RWST level channels due to the absence of bypass indication in the control room. Prior surveillance testing of these normally ce-energized, energize-to-actuate channels has been performed with the tested channel's bistable in the tripped condition This new Action Statement limits the duration that an RWST level channel could be tripped, due to its being inoperable or for testing, in order to limit the probability for automatic switchover to an empty containment sump upon receipt of an inadvertent safety injection signal (SIS) coincident with a single failure of another RWST level channel. This sequence of events,(as shown in Figure 7.6-3 of the Callaway Final Safety AnalysisFSAR), wo Report the containment sump RHR suction valves and, af ter treeting the sprop suction valve open position interlock, the RWST RHR suction valves would close.

l l

. The 72-hour restoration tinie for an inoperable channel is consistent with that given in other Callaway TSs affecting RHR operability; e.g.,

TS 3.5.2 for one ECCS train inoperable and TS 3,8.1.1 for one diesel generator inoperable.

13. BASES 3/4.3.1 and 3/4.3.2 References 3, 4 and 5 were added to the BASES with regard to ESFAS surveillance intervals and allowed outage times. A discussion of analog channel by Ass testing was also added for clarification, consistent with the discussion of item 2.c on Page 11. Attachment 1 of the licensee's letter dated March 19, 1991.

14. Table 3.3-6 Action Statement 27 is renumbered to 38.

4.0 STATE CONSULTATION

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

5.0 ENVIRONMEN1AL CONSIDERATION This amendment involves a change to a requirement with respect to the instal-lation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 or a change to a surveillance requirement. The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types of any effluents that may be released offsite and that there it no r.ignifItant increase in indiddual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this anendment involves no significant hazards consideration and there has been no public comment en such finding (56 FR 24221).

Accordingly, this anendment neets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

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

6.0 C,jLNQUSION The staff has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safet be endangered by operation in the proposed manner, (2) y of the public will not such activities will be conducted in compliance with the Commission's regolations, and (3) the issuance of this anendment will not be inimical to the comon defense end security or to the health and safety of the public.

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7.0 REFERENCES

l 1.

Licensee letter dated October 16, 1985.

2.

Amendment No.17 to Facility Operating License NPF-30, dated September 8, 1986.

3.

Westinghouse Owners Group letter to NRC OG-90-38 dated July 20,1990 (transmitting WCAP 10271, Supplement 2, Revision 1 P-A (updated),

" Evaluation of Survnillance Frequencies and Out of Service Times for the Engineered S / Features Actuation System").

4.

USNRC letter from C.E. Rossi to G.T. Goering, dated April 30, 1990 (NRC Supplemental Safety Evaluation for WCAP-10271, Supplenent 2, Revision 1).

S.

USNRC letter from C.E. Rossi to R.A. Newton dated February 22, 1089 (NRC Safety Evaluation for WCAP-10271, Supplement 2 and Supplement 2 Revision 1).

6.

Amendnent No. 43 to Fh 111ty Operating License NPF-30 dated April 14, 1989.

7.

Licensee letter dated February 7,1989, 8.-

Licensee letter dated August 30, 1988.

9.

Licensee lette,r dated April 12, 1990.

Principal Contributors:

H. T. Lynch Date:

October 9, 1991 m----

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