ML20074A802

Discusses Actions Taken to Identify & Resolve Potential DS-416 Reactor Trip Breaker Problems Per IE Bulletin 83-01. Schedule,W/Finalized Implementation Dates,To Be Submitted by 830531.Emergency Operating Procedures Encl

ML20074A802
Person / Time
Site:	Farley
Issue date:	05/10/1983
From:	Clayton F ALABAMA POWER CO.
To:	Varga S Office of Nuclear Reactor Regulation
Shared Package
ML20074A803	List: ML20074A802 ML20074A811 ML20074A818
References
REF-SSINS-6820 IEB-83-01, IEB-83-04, IEB-83-1, IEB-83-4, NUDOCS 8305160094
Download: ML20074A802 (7)

Text

Mallir.g Address Alabim3 Power CompIny

. 603 North 18th Streat Post Offica Box 2641 Birmingham. Alebama 35291 Telephone 205 783-6081 F. L. Clayton, Jr.

Senior vice President g3h3g3 gg Flintridge Building the southern electic system May 10, 1983 Docket Nos. 50-348 50-364 Di rector, Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washi ngton, D.C. 20555 Atte nti o n: Mr. S. A. Varga Joseph M. Farley Nuclear Plant - Units 1 and 2 Reactor T rip B reakers, DS-416 _

Gentl eme n:

In letters dated March 4,1983 and March 25, 1983 Alabama Power Company described the actions taken in response to I.E. Bulletins 83-01 and 83-04 related to the reactor trip breakers (Model DS-416) at the Farley Nuclear Plant. Since the initial discovery of potential DS-416 breaker problems, Alabama Power Company and Westinghouse have worked in concert to identify and resolve problems associated with the undervoltage (UV) devices. Actions taken by Alabama Power Company have included:

1. Replacement of UV devices with modified devices that have all identified manuf acturing problems corrected and with modified grooves to accomodate imp roved retai ni ng ri ngs.

2. Installation checks on the installed modified UV devices to verify proper alignment and interf ace with the breaker trip shaf t.

3. Testing and maintenance of the DS-416 breakers in accordance with Westi nghouse recommendations. The documentation of actual testing and maintenance, plus procedures by which these activities were conducted, was sent to the NRC Staff on May 2, 1983.

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8305160094 830510 PDR ADOCK 05000348 G PDR l

Mr. S. A. Va rga May 10, 1983 Page 2

4. Licensed operators at Farley Nuclear Plant were notified of the Salem and San Onof re events and were provided a description of the Farley trip breaker operation. In addition, licensed operators received a ref resher review of Emergency Operating Procedures (E0P) related to Anticipated Transients Without Trip (ATWT).

Alabama Power Company has completed all recommended correcti ve actions described in Westinghouse letter dated April 21, 1983 and NRC requi red actions described in I .E. Bulletins 83-01 and 83-04. Alabama Power Company believes that, by completing the recommended corrective actions provided by Westinghouse and NRC, the concerns of potential for misoperation associated with the subject breakers have been adequately addressed. Alabama Power Company currently provides explicit guidance for manual reactor trip in the E0Ps to the licensed operators.

In addition to the actions described above, during telecons on May 3,1983 and May 5,1983, NRC staff personnel identified additional actions that should be performed in order to further assure the reliability of the subject breakers. These actions, which were evaluated by Alabama Power Company and Westinghouse, were discussed with the NRC staf f via telecon on May 6,1983. As a result, Alabama Power Company hereby commits to the following additional actions during a six month period commenci ng May 6,1983:

1. Six Month Interval Bench Test and Maintenance (Main and bypass breakers)

a. Obtain the following "as found" data:

i) Breaker response time measured during 3 consecutive tests of tripping each by UV and by shunt coils.

ii) Measu rement of force requi red to actuate trip bar.

iii) Measu rement of force exerted by UV device output.

Note: The performance of item ii) and iii) is

( predicated on the ability of Alabama Power Company and Westinghouse to develop "in-the-field" test techniques with appropriate acceptance criteria, which will provide baseline data to be considered in future breaker maintenance activities. Development of procedu ral guidance is scheduled for August 1983.

b. Perform breaker preventive maintenance:

Alabama Power Company will perform preventive maintenance including lubrication, cleaning, etc.

Mr. S. A. Varga May 10, 1983 Page 3

2. Monthly testing (main breakers in-place)

a. Functional test of UV devices by Reactor Protection System (RPS) actuation including response time testing of the breaker.

Note: Presently 'the capability to measu re the response time of breaker actuation is not possible using installed equipment. A design to allow such response time testing is expected to be completed in June 1983. Installation 1

of this change, which is expected to requi re a pl. ant outage, will be completed du ri ng the fi rst outage of sufficient duration after completion of design and receipt of material. Confidence in the response capability of the UV devices is currently provided by the following:

i) Monthly RPS test of the UV device will be conducted for each train which includes verification that the breakar opens promptly. Monthly testing of both t ra will next be perf ormed by June 6,1983.

Currently, the UV device testing is done on a monthly basis, ii) Response time testing of the subject breakers was successfully performed during bench testing in April 1983.

b. Functional manual test of shunt device.

Note: The present Farley Nuclear Plant design does not ,

allow the performance of this functional test f rom the breaker cabi net usi ng i nstalled equipment. A design to allow this testing is expected to be complete during June 1983. Upon finalization, the design will be provided to NRC for app roval . Installation of this change, which is expected to requi re a plant outage, will be completed during the first outage of sufficient duration af ter completion of design and receipt of material.

3. Pre-startup testing (main breakers)

These pre-startup tests will be conducted an both train breakers prior to each criticality unless such testing has been completed within the past seven days.

a. Functional test of the reactor trip breakers via the main control board trip switches.

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Mr. S. A. Varga May 10, 1983 Page 4

b. Functional independent test of shunt devices f rom the breaker cabi net.

Note: As presently designed, independent testing cannot be performed with installed equipment. In conjunction with the design change described in Item 2.b above, the capability to independently test these devices will be 3

added.

4 Provide RPS Actuation of the Shunt Trip' In conjunction with the design change described in Items 2.b and 3.b, this capability will be added. This design is expected to be consistent with that of the Westinghouse Owners Group. Upon finalization, the design will be provided to NRC for approval.

5. UV Device Confirmatory Life Testing Alabama Power Company and Westinghouse are developing a program for confirming, via test and/or calculation, the expected life of the UV

, de vi ces . The scope and objectives of this program are expected to be completed during June 1983. Upon finalization, the program will be provided to NRC for approval.

6. Procedural Modification and Operator Training

a. Procedural Modifications After discussions held with the NRC staff on May 6 and May 9, 1983 concerning operator actions during an ATWT condition, Alabama Power Company has modified the E0Ps related to ATWT and Reactor Trip. These modifications more clearly delineate

, operator response in order to preclude potential op- ator j inaction as a result of surveying various plant i nt rumentation unnecessarily (i .e., failure to manually trip reactor in a timely manner). Attached are copies of the revised E0Ps (E0P-5 and E0P-15) .

During these discussions, considerable interest was expressed concerning the rationale for the steps appearing in the procedures for observing "all full length rods fully inserted and nuclear power decreasing" as confirmation of a reactor t ri p . The following discussion is provided as basis for retai ning this procedu ral provision.

Farley Nuclear Plant has two licensed operators per unit called the Operator at-the-Controls (0ATC) a1d Unit Operator (U0). The 0ATC is stationed in the At-the-Controls area of the control l

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Mr. S. A. Varga May 10, 1983 Page 5 room at all times; his work station (i .e., desk and chai r) is located di rectly in f ront of the reactor control panel. This panel is where the key instrument stion and controls equipment discussed below are located. If a reactor trip has occurred, the OATC need only glance at the Digital Rod Position Indication (Figure 1) which displays in prominent f ashion with bright red lights each rod's actual rod position. On this same panel in the same area, indicators and recorders prominently display Reactor Power for the 0ATC (Figure 1). This verification process would be completed almost instantaneously by the 0ATC.

If the reactor is not tripped as evidenced by all contr ol rods not fully inserted and nuclear power not decreasing, the 0ATC is immediately alerted that an Anticipated Transient Without Trip (ATWT) is potentially occu rring. The 0ATC now proceeds to determine if a condition requiring a reactor trip exists. If the condition does exists, the 0ATC immediately trips the rea ct o r. This decision process of verifying the state of the reactor is engrained in licensed operators by repeated classroom t rai ning, walk-th roughs and simulator t rai ning. It has become an almost automatic response for these personnel.

If the verification of determining that "all full length rods fully inserted and nuclear power decreasing" is not allowed, reactor plant safety could be decreased by the following detrimental ef fects:

1) Requi ring that an operator take action p rior to verification that an off-normal event has occurred may result in an operator taking action counter to safe operating practice.

Such a requi rement is counter to the basic instincts that I are taught and necessary for safety throughout operations.

To require operator performance otherwise might result in an unpredictable operator response.

2) Challenges to reactor safety systems could be increased by tripping the reactor on invalid indications.

Therefore, Alabama Power Company strongly feels that the

' verification of "all rods fully inserted and nuclear power decreasing" is essential for taking safe action during a reactor trip or ATWT.

b. Operator Traini ng Based on I.E. Bulleti n 83-01 dated February 25, 1983, Fa rl ey Nuclear Plant licensed operators were notified of the f ailu re-to-t rip i ncident at Salem and were requi red to perf orm a l

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Mr. S. A. Va rga May 10, 1983 Page 6 ref resher review of the Farley Emergency Operating Procedure related to Anticipated Transients Without Trip prior to relieving the fi rst shif t af ter mid-day on February 26, 1983.

Based on I.E. Bulletin 83-04, Farley Nuclear Plant licensed operators were notified upon thei r arrival on-shif t of the testing failures at San Onof re Units 2 and 3, were reminded of the Salem incident, and were required to perform an additional ref resher review of the Farley Emergency Operating Procedures related to Anticipated Transients Without Trip prior to relieving their first shift commencing with the evening shift on March 15, 1983.

On April 15, 1983, as a result of a possible problem with FNP reactor trip breakers discovered during preventive maintenance change out of each undervoltage-coil (subsequently determined to be non-generic), the Farley Nuclear Plant operators were informed that their Reactor Trip Breakers may not function and symptoms and actions requi red of E0P-5 and E0P-15 were discussed.

I Recently, changes have been made to E0P-5 and E0P-15, as described above, to clarify the symptoms of ATWT. All on-shift licensed personnel and Shif t Technical Advisors (STA's) were required to be briefed on this change by the Shift Supervisor prior to relieving thei r next shif t.

As a result of discussions held with the NRC on May 6 and May 9, 1983 procedure changes have been made to E0P-15 to further clarify the symptoms of ATWT. All on-shif t licensed personnel and STA's will be required to be briefed on this change _ by the shif t supervisor prior to relieving thei r next shif t.

In response to the reactor trip breaker opening failures at the Salem Nuclear Generating Plant, Farley Nuclear Dlant license requalification training has addressed the reactor trip breaker event at Salem. Included in this discussion has been the sequence of events on the two addressed occurrences, the physical operation of Salem's and Farley Nuclear Plant's reactor -~ -

trip breakers, NRC's concerns and responses, and the operator's

. response if such an event occurred at Farley Nuclear Plant.

E0P-5.0, " Reactor T rip" and E0P-15.0 " Anticipated T ransient Without a Trip" were specifically emphasized. The philosophy of performi ng a manual reactor trip anytime the ATWT symptoms were observed was specifically stressed.

Since it has been impossible to finalize the details of the committed design changes, test procedures and confirmatory life program by May 10, 1983, a follow-up status letter will be submitted by May 31, 1983, to provide a more complete schedule with finalized implementation l

Mr. S. A. Varga May 10, 1983 Page 7 dates. Upon completion of the six month test program described above, Alabama Power Company will submit a summary report concerning this testing and will address continued testing.

Please advise if there are any questions regarding these committed a cti vi ti es .

You rs very truly,

?/ % t, p F. L. Clayton, J r.

FLCJ r/RLG: dd r-D22 Attachments cc: Mr. R. A. Thomas Mr. G. F. Trowbridge Mr. J. P. O'Reilly Mr. E. A. Reeves Mr. W. H. B radf ord e dg

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