ML20134P984

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Application for Amend to License NPF-15,which Would Clarify in Note Which Relays Will Not Be Response Time Tested Until Next Songs,Unit 3 Refueling Outage to Satisfy SR 3.3.5.6 of TS 3.3.5, ESFAS Instrumentation
ML20134P984
Person / Time
Site: San Onofre Southern California Edison icon.png
Issue date: 02/21/1997
From: Nunn D
SOUTHERN CALIFORNIA EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20134P987 List:
References
NUDOCS 9702260193
Download: ML20134P984 (9)
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e h $O01Hf RN CAuf 0RNIA Dwight E. Nunn

{ Vice President An EDISON INTIRNATIOML Company l February 21, 1997 U. S. Nuclear Regulatory Commission Attention: Document Control Desk '

Washington, D.C.20555 Gentlemen:

Subject:

Docket Nos. 50-362 Engineered Safety Features Response Time Testing Proposed Technical Specification Change Number 480, Supplement 1 San Onofre Nuclear Generating Station, Unit 3

Reference:

February 18, 1997 letter from R. W. Krieger (Edison) to William H. Bateman (NRC),

Subject:

Engineered Safety Features Response Time Testing Proposed Technical Specification Change Number 480, San Onofre Nuclear Generating Station, Unit 3 Enclosed is Supplement 1 to Amendment Application Number 152 to Facility Operating License NPF-15 for the San Onofre Nuclear Generating Station (SONGS), Unit 3. The Amendment Application consists of Proposed Technical Specification Change Number 480 (PCN-480), Supplement 1.

As discussed with the NRC Project Manager for San Onofre Units 2 and 3, this supplement revises the Note being added to Surveillance Requirement 4 (SR) 3.3.5.6. This revision is to clarify in the Note which relays will not i be response time tested until the next San Onofre Unit 3 refueling outage to satisfy SR 3.3.5.6 of Technical Specification (TS) 3.3.5, " Engineered Safety Features Actuation System (ESFAS) Instrumentation." In addition, the discussion is updated to reflect that all the ESFAS subgroup relays in Unit 3 ,

that can be response time tested on-line have been tested. l If you would like additional information regarding this Amendment Application, please let me know. I Sincerely, ME L l x ao003 Enclosure cc: J. E. Dyer, Acting 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 j M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3

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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Application of SOUTHERN CALIFORNIA EDIS0N COMPANY, ET AL. 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, Supplement 1.

SOUTHERN CALIFORNIA EDISON COMPANY, ET AL. pursuant to 10 CFR 50.90, hereby submit Amendment Application No 152, Supplement 1. This amendment application consists of Proposed Technical Specification Change No. 480, Supplement 1 to Facility Operating License NPF-15. Proposed Technical Specification Change No. 480, Supplement 1 is a request to revise TS 3.3.5, " Engineered Safety Features Actuation System (EFSAS) 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 , day of Vlubr7 7 , 1997.

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Respectfully submitted, SOUTHERN CALIFORNIA EDIS0N MPANY ByIv k 3

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Dwight E. Nuran Vice President l

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State of California '

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CountyofSapDiego r On _? r 71 I Q 0 beforeme,l,?[kflll110) LM b;W h sona11y appeared D0lGhP6kht MB , personally known to me to be the person whose name is subscribed to the within instrument and acknowledged to me that he executed the same in his authorized capacity, and that by his signature on i 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. -

MAmANE SANCHE2 ,

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COMM. # 1033763 Notcry Public - Co;fe g

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DESCRIPTION AND SAFETY ANALYSIS OF PROPOSED CHANGE 480 This is a request for an exigent Technical Specification (TS) change to revise Surveillance Requirement (SR) 3.3.5.6 of TS 3.3.5, " Engineered Safety Features '

Actuation System (ESFAS) Instrumentation" for San Onofre Nuclear Generating Station (SONGS), Unit 3.

Existing SONGS Specification:

Unit 3: See Attachment "A" l

Preposed 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 30 subgroup relays Mehtifiedith thsifebruary,318M1997? Edison;1etter is not applicable until return f6~MBde

~4"ffoin'thE~ Unit *3^Cicle"9"fefneling outage? with the additional commitments made in the February 18, 1997 Edber, letter. The safety  :

justification for not performing this testing is also included in the 1 February 18, 1997 letter.

DESCRIPTION OF CHANGES 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 the 30 rubgroup relays in the Engineered Safety Features Actuation System (ESFAS) listed in Attachment C. In the event of a planned or unplanned shutdown of Unin s . ar to the Cycle 9 refueling outage, testing of these 30 relays in accord _.._ .,2 SR 3.3.5.6 will be completed prior to increasing in Modes from that shutdown.

DISCUSSION On February 14, 1997, Southern California Edison (Edison) recognized that the 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 relays 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 it:

Mode 1 would involve more risk of inadvertent actuation of ESF equipment and l trip of the Unit.

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e 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 for relay operation, and the recent {

maintenance history of the relays. '

System Description  ;

The subgroup relays are part of the Engineered Safety Features (ESF) systems. l The safety-related instrumentation and controls of the ESF systems include the j ESFAS, which consists of the electrical and mechanical devices and circuitry (from sensors to actuation device input terminals) involved in generating those signals that actuate the required ESF systems, and the arrangement of components i 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 Injection System
  • Containment Isolation ,
  • Containment Cooling ,

i The signals from the ESFAS actuate the ESF equipment. For the above actuation 1 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 neans 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 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 wn based on testing completed from a large sample of relays tabulated by relay type.

Three standard deviations were applied to the average of the relay times and the  !

result was conservatively rounded up to 0.300 seconds.

Subgroup Relays j 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. l Although earlier versions of these relays have had a history of performance 1 problems, these issues have been addressed and resolved as discussed below.

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 2

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i present on and around the bearing surfaces and in bushing to shaft spaces where '

the buildup of material caused the relay to mechanically jam.

1The 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  ;

primary driving force for the problem was excess heat (temperature) generated by t coil voltages 10% or more above nominal operating voltage. ,

Edison and other utilities worked with Potter & Brumfield to correct all the '

i 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 l' 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 i 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 _infonnation. 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 accommodate the actual response time for these relays.

A:, 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 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.

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In response to this missed surveillance,' Edison placed a Mode 4 restraint on the.  !

Unit'2 refueling outage, and a complete retest was immediately initiated and has  !

! been completed g et all the ESFAS subgroup relays addressed by SR 3.3.5.6. .

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! Additionally, response time testing was initiated )mdjtoeg'Risp5nse liiiie data Unit 3ESFASsubgrouprelaysthatcanbetestedonkliEs7  !

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 j j

100 relays. Respons,e

.... __ __ co time data m, u collected on t___Unit 3 ?..a__

sub roup relays ( rr:.'ly,

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' range gjjygtiilitMiClie]6Eds'tT07115'~sEE6Kd(s7^TnsiiIn[sults of"0 029Tec are an improvem l data obtained in 1983 for the previous version subgroup relays and support the i bounding time' response allowance of 0.300 seconds used for the subgroup relays.  !

1 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 I period after the relays were replaced.

In addition, all ESF trains have successfully passed the following surveillance }

tests. 4 i

1. Channel Functional Test (SR 3.3.5.2, SR 3.3.5.3, SR 3.3.5.7, i i

SR3.3.6.1,andSR3.3.6.3)  ;

l 2. Channel Calibration Test (SR 3.3.5.4 and SR 3.3.5.5)  !

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3. Subgroup Relay Test (SR 3.3.6.2) l 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

! that the time response of the subgroup relays is within the assumed allowance of 0.300 seconds because:

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 February 14 -17, 1997 demonstrated that the timing of the subgroup l 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, f

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

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  • In addition, based on the current tests of record for the Unit 3 integrated ESF  ;

L test per SR 3.8.1.19, 10 subgroup relays plus actuated components were 3

demonstrated to be well within their overall response time requirement.

, Probable Risk Assessment j 4

l 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 overall ESF response time remains within allowable design margins, no events modeled in the San Onofre Units 2 and 3 living probable 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 l surveillance testing during the next outage.

This proposed change is requested to defer implementation of SR 3.3.5.6 until l the next refueling outage on Unit 3 for 30 ESFAS subgroup relays. This proposed 1 change will preclude the need to shut down Unit 3 before the refueling outage j for the sole purpose of performing this SR. The start of the Unit 3 Cycle 9 l refueling outage is currently anticipated for April 12, 1997.

SAFETY ANALYSIS j

. 8 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 tMs proposed  ;

change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No l

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.  ;

Operation of the facility would remain unchanged as a result of the I 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 pr9 posed 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 previously evaluated?

l 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.

i Operation of the facility would remain unchanged as a result of the proposed change. No equipment change or operating procedure change is l

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being made. Therefore, the proposed change will not create the possibility of a new or different kind of accident from any accident 1

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 l 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. Based on other surveillance testing, the response time margin available for i 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, l this proposed change does not involve a significant reduction in a margin of safety. 1 Safety and Significant Hazards Determination  ;

Based 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 j station on the environment as described in the NRC Final Environmental Statement.

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ATTACHMENT A (Existing Specifications)

Unit 3 i I

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