ML20138L101

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Application for Amend to License NPF-15,to Defer Implementation of SR 3.3.5.6 of TS 3.3.5, ESFAS Instrumentation, for 30 Subgroup Relays Until Next Refueling Outage on Songs,Unit 3
ML20138L101
Person / Time
Site: San Onofre Southern California Edison icon.png
Issue date: 02/18/1997
From: Nunn D
SOUTHERN CALIFORNIA EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20138L106 List:
References
NUDOCS 9702210067
Download: ML20138L101 (9)
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g so - cio.o. m EDISON  ?"S""  !

'An unsonirtwnom came.n l T

l February 18, 1997

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'i O. S. Nuclear Regulatory Commission i Attention: Document Control Desk l Washington, D.C.20555 j Gentlemen: l l

Subject:

Docket Nos. 50-362 'l Engineered Safety Features Response Time Testing Proposed- j Technical Spectfication Change Number 480 i' San Onofre Nuclear Generating Station, Unit 3

Reference:

.-February 16, 1997 letter from R. W. Krieger (Edison) to-William H. Bateman (NRC),

Subject:

. Request for Enforcement Discretion, Engineered Safety Features Response Time Testing, San Onofre Nuclear Generating Station, Unit 3 Enclosed is Amendment Application Number 152 to Facility Operating License

.NPF-15, for the_ San Onofre Nuclear Generating Station (SONGS), Unit 3. The l

Amendment Number 480_ PCN-480) Ap(plication

. This isconsists a requestoffor Proposed an exigentTechnical Technical Specification Change l Specification Change as a followup to the Request for Enforcement Discretion l referenced above. j The proposed change is requested to defer implementation of Surveillance i Requirement- (SR) 3.3.5.6 of Technical Specification (TS) 3.3.5, " Engineered l Safety Features Actuation System (ESFAS) Instrumentation" for 30 subgroup  !

relays until the next refueling outage on San Onofre Unit 3. The need for {'

[ 'this recuest results from an error in implementation of this SR.This SR was

. believec to be satisfied by a surveillance which included a bounding allowance  ;

a for the subgroup relays, in lieu of actually testing these relays. l This change is not being requested for Unit 2 because Unit 2 is currently i

shutdown for a_ refueling outage. The ESFAS subgroup relays.in Unit 2 will be j tested:in accordance with SR 3.3.5.6 prior to return to Mode 4. l i- The-Southern California Edison Company requests this amendment be issued as an exigent TS change, effective as of its date of issuance. The exigent i
' . circumstances for this TS amendment request exist because it would avoid'an  !

4 undesirable transient associated with an unnecessary plant shutdown and thus i minimize potential safety consequences and operational risks associated with l such' action. In the event of a planned or unplanned shutdown of Unit 3, prior :l to_the Cycle 9 refueling outage, testing in accordance with SR 3.3.5.6 will be j i I

completed prior to increasing in Modes from that shutdown. j j P. O. Box 128 P k M !6 pg g a lh -

j San Clemente CA 92674 0128  !

714-368 148o  !

. Fax 714 3681490 l y 3

e Document Control Disk If you would like additional information regarding this Amendment Application, please let me know.

5 Sincerely

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l Enclosure cc: L. J. Callan, Regional Administrator, NRC Region IV K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 & 3 M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3 t

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Document Control Desk UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Application of SOUTHERN CALIFORNIA )

EDIS0N COMPANY, ET 6L. for a Class 103 Docket No.

License to Acquire, Possess, and Use 50-362 a Utilization Facility as Part of Amendment Unit No. 3 of the San Onofre Nuclear Application Generating Station No 152.

SOUTHERN CALIFORNIA EDISON COMPANY, ET AL. pursuant to 10 CFR 50.90, hereby submit Amendment Application No 152. This amendment application consists of Proposed Technical Specification Change No. 480 to Facility Operating License NPF-15. Proposed Technical Specification Change No. 480 is a request to revise TS 3.3.5, " Engineered Safety Features Actuation System (EFSAS) l Instrumentation." The proposed change defers implementation of Surveillance Requirement 3.3.5.6, " Verify ESF RESPONSE TIME is within limits" until the Unit 3, Cycle 9 refueling outage.

Subscribed on this 'b d ay of dI)f'll OL NA , 1997.

J Respectfully submitted, SOUTHERN CALIFORNIA EDIS0N COMPANY F

Dwight E. Nunn Vice President

Document Control Desk State of California County of an Diego tr On b lf 47 _

beforeme,[,'tTIl4 s_ N4Cb M rsonally <

appeared Olts i%htM Alluut, personally known to me to be the person whose i nameissubscribedtothewithininstrumentandacknowledgedtomethat he executed the same in his authorized capacity, and that by his signature on the instrument the person, or the entity upon behalf of which the person acted, executed the instrument.

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WITNESS my hand and official seal. j mewan COMM.# 1033763

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l Notory Pub 8c - Cotfornia p ( ORANGE COUNTY My Comm. Expires OCT 14.19 Signaturk O (Ibf e- -

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l DESCRIPTION AND SAFETY ANALYSIS )

0F PROPOSED CHANGE 480  ;

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This is a request for an exigent Technical Specification (TS) change to revise l Surveillance Requirement (SR) 3.3.5.6 of TS 3.3.5, " Engineered Safety Features Actuation System (ESFAS) Instrumentation" for San Onofre Nuclear Generating I Station (SONGS), Unit 3.

Existing SONGS Specification:

Unit 3: See Attachment "A" Proposed SONGS Specification:

- Unit 3: See Attachment "B"

- The following Note will be added to SR 3.3.5.6:

Verification of the RESPONSE TIME of the subgroup relays is not applicable until return to Mode 4 from the Unit 3 Cycle 9 refueling outage with the l additional commitments made in the February 18, 1997 Edison letter. The .

safety justification for not performing this. testing is also included in the February 18, 1997 letter. ,

Description of Chances SUMARY The proposed change is requested to defer implementation of Surveillance Requirement (SR) 3.3.5.6 of TS 3.3.5, " Engineered Safety Features Actuation System (ESFAS) Instrumentation" until the Unit 3, Cycle 9 refueling outage for i the 30 subgroup relays in the Engineered Safety Features Actuation System (ESFAS) listed in Attachment C. In the event of a planned or unplanned shutdown of Unit 3, prior to the Cycle 9 refueling outage, testing of these 30 relays in accordance with SR 3.3.5.6 will be completed prior to increasing in Modes from i that shutdown.

DISCUSSION i

On February 14, 197 Southern California Edison (Edison) recognized that the 3

existing Unit 3 surveillances of record did not fully satisfy SR 3.3.5.6. The SR requires verification that the ESF Response Time is within limits, which requires that the response time of the subgroup relays be measured. Although it ,

may be possible to perform this test with the Unit in Mode 1 for the 30 subgroup relays listed in Attachment C, it would involve testing these relrys inside the ESF cabinets using temporary jumpers and power supplies for safety significant ,

components (main steam isolation valves, feedwater valves, reactor coolant pump

bleedoff, instrument air, and component cooling water), as well as defeating the safety function of these. relays during testing. Performance of this testing in Mode 1 would involve more risk of inadvertent actuation of ESF equipment and  ;

trip of the Unit. .

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After reviewing existing documentation, however Edison believes that the subgroup relays are fully functional and capable of performing their intended safety functions,-.as demonstrated by satisfactory performance during'other surveillance testing, the margin available fortrelay operation, and the .recent l

maintenance history of the relays, j

-System Description j The subgroup relays are part of the Enginecred Safety Features (ESF) systems.- l The safety-related instrumentation and controls of the ESF systems' include the i

. ESFAS, which consists of. the electrical and mechanical: devices and circuitry L(fromsensorstoactuationdeviceinputterminals)involvedingeneratingthose signals,that actuate the required ESF systems, and the arrangement of components ,

that perform protective actions after receiving a signal from either the ESFAS

or the operator. ,

The-ESFAS includes sensors'to monitor selected safety significant parameters; The following actuation signals are generated.by the ESFAS when the monitored variables reach the levels that.are indicative of conditions which require protective. action:  ;

  • Safety'InjectionSystem
  • Containment Isolation .
  • Containment Cooling-  !

t The signals from the ESFAS actuate the ESF equipment. .For the above actuation ,

systems, two-out-of-four coincidence of like initiating trip signals from four  ;

independent measurement channels is required to actuate the ESF system.  !

The response time of the ESF systems may be measured by means of any series of ,

sequential, overlapping, or total steps so that the entire response time is  !

measured. At San Onofre the total response time has been determined by i sequentially adding the response times determined for separate segments of the

~ESF. systems. Response times have been measured during each surveillance from the sensor / transmitter to the subgroup relay and from the subgroup relay until '

the ESF equipment is capable of performing its safety function. However, instead of being measured during each surveillance, a bounding time response allowance was used for the subgroup relays based on measurements and an ,

engineering evaluation performed in 1983. The bounding time was based on testing '

completed from a large sample of relays tabulated by relay type.

Three st'andard deviations were applied to the average of the relay times and the  ;

result was conservatively rounded up to 0.300 seconds.

Subgroup Relays

! The subgroup relays are Potter & Brumfield Motor Driven Relays. These relays  :

' utilize a coil-to. rotate a shaft which causes the contacts to open and close.

Although earlier versions of these relays have had a history of petformance problems, theseLissues have been addressed and resolved as discussed below.

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During a Unit 2 integrated ESF test in November, 1987, one subgroup relay did not function properly. Examination of the relay revealed the presence of contamination and corrosion products in the motor housing. These materials were present on and around the bearing surfaces and in bushing to shaft spaces where the buildup of material caused the relay to mechanically jam.

The failure mode was found to be predominately one of relay binding due to "out-gassing" of corrosive material in the insulating varnish of the relay coil.

The out-gassed material would condense on the internal surfaces of the relay, such as the shaft and shaft bearing surface, causing corrosion and binding. The (temperature) primary driving force for the problem was excess heatgenerated b voltage.

Edison and other utilities worked with Potter & Brumfield to correct all the problems experienced. The changes included using an epoxy coil coating instead of varnish to eliminate chlorine, replacement of the brass spacers with stainless steel for enhanced corrosion resistance, tolerance changes to alleviate shaft binding, and replacement of the coil PVC insulating sleeves and neoprene grommets in the motor base with inert materials to eliminate these sources of corrosive out-gassing materials.

Revision controlled drawings were instituted with the vendor guaranteeing no changes to subgroup relays purchased by San Onofre without Edison approval.

Unique part numbers were assigned to further track changes and subsequent replacement of existing subgroup relays. On-site Quality Control inspection and testing was used to " qualify" the vendor for the new design subgroup relays.

The subgroup relays in ESF systems with varnish coils were replaced in the 1989 to 1993 time frame.

Justification of Operability Edison has completed a number of activities including 1) an assessment of the total time sequence for the individual ESF subgroup relays, 2) initial Unit 2 relay testing, 3) a maintenance history search for relay reliability, and

4) an evaluation of recent channel test results.

The tables in Attachment D provide the individual relay and component timing data for both Units 2 and 3 Trains A and B ESF equipment. The information in the tables was pulled from plant records on February 14 - 17, 1997 and is the best available information. The tables list the individual relays, the associated valve or pump that is actuated, timing data for the trains, the technical specification limit for the component, and allowable " margin" to the limit. Note that the table shows a "zero" time for the subgroup relays. This "zero" time is shown so that the allowable margin column effectively shows the time available to accomodate the actual response time for these relays.

As shown in the attached tables, there are 118 subgroup relays in the ESF relay cabinets. Edison has further evaluated each relay and actuated component. Of these 118 relays, 99 are required to be response time tested to comply with SR 3.3.5.6. As a result of the integrated ESF testing, response time data is credited for 10 of these relays. Of the remaining 89 relays, 59 can be response time tested on line. The remaining 30 relays cannot be response time tested 3

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on-line without rendering their associated equipment inoperable and incapable of .

performing their safety functions. These 30 relays close valves that are  !

required to be open while the plant is operating in systems such as main steam '

isolation, main feedwater, reactor coolant pump bleedoff, component cooling water noncritical loop, and instrument air.  ;

-In response to this missed surveillance, Edison placed a Mode 4 restraint on the i Unit 2 refueling outage, and a complete retest was immediately initiated and has ,

-been completed of all the ESFAS subgroup relays addressed by SR 3.3.5.6.

Additionally, response time testing was initiated on the Unit 3 ESFAS subgroup relays that can be tested on line. Response time data collected on' subgroup.

relays tested on Unit 2 shows time responses-in the range of 0.032 seconds to 0.119 seconds. This' testing includes a. sample of over 100 relays. Response time data collected on_ Unit 3 subgroup relays (currently, response time. testing on 52 of 59 relays has been completed on line) shows time response in the range of 0.029 seconds to 0.115 seconds. These results are an improvement over data obtained in 1983 for the previous version subgroup relays and support the 1 bounding time response allowance of 0.300 seconds used for the subgroup relays. l

-A' maintenance history search for ESF subgroup relay failures was completed.

This search found no failure on either San Onofre unit since the 1989-1993 time ,

period after the relays were replaced.  ;

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In addition,'all ESF trains have successfully passed the following surveillance tests: ,

1. Channel Functional Test (SR 3.3.5.2, SR 3.3.5.3, SR 3.3.5.7, SR3.3.6.1,andSR3.3.6.3) i
2. Channel Calibration Test (SR 3.3.5.4 and SR 3.3.5.5) -l
3. Subgroup Relay Test (SR 3.3.6.2)

The ESF trains have satisfied the above surveillance test acceptance criteria, which provides assurance that the ESF trains are operable. .

In summary, Edison is confident that the Unit 3 ESF trains remain operable and l that the time response of the subgroup relays is within the assumed allowance of 0.300 seconds because: ,

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1. There is sufficient available margin for subgroup relays that are '

not currently timed (see Attachment D tables),

2. Results of Unit 2 subgroup relay testing conducted on I February 14 - 17, 1997 demonstrated that the timing of the subgroup ,

relays was consistent with and bounded by the 1983 assessment, ,

3. There~is no history of ESF subgroup relay failure since the

'1989-1993 time period.  !

4.- Surveillance requirements for ESF Channel Functional Tests, ESF Channel Calibration Tests, and ESF Subgroup Relay Tests have been satisfied.

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In-addition, based on the current tests of record for the Unit 3 integrated ESF '

test per.SR 3.8.1.19, 10 subgrou ) relays plus actuated components were demonstrated to be well within t1eir overall response time requirement.

Probabilistic Risk Assessment

.The core damage and significant radioactive release risk impact of continued Unit 3 operation without performing the subject ESF surveillance testing has been determined negligible. -Since the engineering assessment concludes that the overal1 ESF 79sponse time remains within allowable design margins, no events modeled in the San Onofre Units 2 and 3 living probabilistic risk assessment are impacted. The impact on core damage risk from a forced unit shutdown to perform.

the subject surveillance test is estimated to be IE-6, which is non-negligible.

Therefore, the safest course of action is to remain at power and conduct the surveillance testing during the next outage.

This proposed change is requested to defer implementation of SR 3.3.5.6 until the next refueling outage on Unit 3 for 30 ESFAS subgroup relays. This proposed ,

change will preclude the need to shut down Unit 3 before the refueling outage for the sole purpose of performing this SR. The start of the Unit 3 Cycle 9 refueling outage is currently anticipated for April 12, 1997.

SAFETY ANALYSIS' The proposed change described above shall be deemed to involve a significant hazards consideration if there is a positive finding in any one of the following areas:

1. Will operation of the facility in accordance with this proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No The proposed change would defer completion of Surveillance Requirement (SR) 3.3.5.6 of Technical Specification (TS) 3.3.5 for 30 Emergency Safety .

Feature Actuation System (ESFAS) subgroup relays until the Unit 3, Cycle 9 refueling outage.

l Operation of the facility would remain unchanged as a result of the proposed change and no assumptions or results of any accident analyses are affected. Based on other surveillance testing, the response time margin available for these subgroup relays, results of response time testing on Unit 2 relays, and the history of no failures since the 1989 to 1993 time period, the capability of these ESFAS subgroup relays to perform their specified safety function has been demonstrated and they are operable.

Therefore, the proposed change will not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Will operation of the facility in accordance with this proposed change create the possibility of a new or different kind of accident from any accident previoucif evaluated?

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i Response:No  ;

The proposed change would defer completion of SR 3.3.5.6 of TS 3.3.5 for

.30.ESFAS subgroup relays _until the Unit 3, Cycle 9 refueling outage. l Operation of the facility would remain unchanged as a result of the  ;

proposed change. No equipment change or operating procedure change is  :

being made. Therefore, the proposed change will not create the  ;

i possibility of a new or different kind of accident from any accident i previously evaluated.  ;

3. Will operation of the facility in accordance with this proposed -

change involve a significant reduction in a margin of safety?  ;

Response:No The proposed change'would defer completion of SR 3.3.5.6 of TS 3.3.5 for  !

4 30 ESFAS subgroup relays until the Unit 3, Cycle 9 refueling outage. i 7

Based on other surveillance testing, the response time margin available

for these subgroup relays, and results of testing on Unit 2 relays,-the
capability _ of these ESFAS subgroup relays to perform their specified ,

safety. function has been-demonstrated and they are operable. Therefore, i this proposed change does not involve a significant reduction in a margin  :

of safety. j Safety and Significant Hazards Determination  ;

. dased on the above Safety Analysis, it is concluded that: (1) the proposed  ;

change does not constitute a significant hazards consideration as defined by ,

. 10 CFR 50.92 and (2) there is reasonable assurance that the health and safety of the public will not be endangered by the proposed change. Moreover, because  !

this proposed change does not involve a significant hazards consideration, it  ;

will also not result in a condition which significantly alters the impact of the i

station on the environment as described in the NRC Final Environmental  !

q Statement.

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