ML20129F061

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Application for Amend to License NPF-43,revising Tech Spec 4.8.4.3 Re Periodic Testing Requirement for Thermal Overload Protection Devices
ML20129F061
Person / Time
Site: Fermi DTE Energy icon.png
Issue date: 09/25/1996
From: Gipson D
DETROIT EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20129F066 List:
References
CON-NRC-96-0085, CON-NRC-96-85 NUDOCS 9610010241
Download: ML20129F061 (10)
v • d • e


Text

I

, s Dzugiss R. Clpson. ,

Seruor Vee Pres 4ent l Nuclear Generation Form 12 6400 North Dsse Hghway Newport.M.chgan 48166 p13) 58t%5249 September 25,1996 .

NRC-96-0085 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

Reference:

Fermi 2 NRC Docket No. 50-341 NRC I,icense No. NPF-43

Subject:

Proposed Technical Specification Change (License Amendment) - Periodic Testing Requirement for Thermal Overload Protective Devices

This application proposes to delete the requirement for the periodic testing of Thermal Overload (TOL) Devices. Also, this change clarifies the situational testing requirement. This change is proposed to improve the reliability of safety related Motor Operated Valves (MOVs), increase overall plant safety, and eliminate related F

testing costs. In addition, the Bases of Technical Specification 3/4.8.4 is being revised to reflect the proposed changes.

The change to delete the requirement for periodic testing of TOL protective devices is being submitted as a Cost Beneficial Licensing Action. This proposalinvolves an increase in plant safety and will save over $500,000 through the life of the plant, not .

. including costs of replacement power. Cost savings are based on avoiding the costs of performing each work activity associated with the periodic testing of the TOL protective devices.

The description and evaluation of the changes are included in Attachment 1 to this letter. Attachment 2 contains the proposed Technical Specification page revisions.

[f I 9610010241 960925 PDR.' ADOCK 05000341L P PDR '

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USNRC l

September 25,1996 i' NRC-96-0085

Page 2 Detroit Edison requests that this amendment be approved with an implementation time period of"within 60 days."

Detroit Edison has evaluated the proposed Technical Specification change against the criteria of 10CFR50.92 and determined that No Significant Hazards Consideration is

, involved. The Fermi 2 Onsite Review Organization has approved and the Nuclear Safety Review Group has reviewed the proposed Technical Specification and concurs

with the enclosed determinations. (to be venfiedprior to submittal) in accordance with 10CFR50.91, Detroit Edison is providing a copy of this letter to the State of j Michigan.

3 No commitments are made in this letter. If you have any questions, please contact j Joseph Conen at (313) 586-1960.

Sincerely, b

J 4

i

Attachments

! cc: A. B. Beach A. J. Kugler j M. J. Jordan A. Vegel i

Supervisor, Electric Operators, Michigan

, Public Service Commission, J. R. Padgett o

USNRC September 25,-1996 l NRC-96-0085

' Page 3 I, DOUGLAS R. GIPSON, do hereby affirm that the foregoing statements are based on facts and circumstances which are true and accurate to the best of my knowledge and belief.

DOUGLAS R. CflPSON Senior Vice President On this 23 d day of Mb .1996 before me personally appeared Douglas R. Gipson, being first duly sworn and says that he executed the foregoing as his free act and deed.

<4 otary Public JUDITH A. RAY Notary Putgic, Wayne County, Mt My Conrusion Expires Apr.4,1998

' Cfdad t&w

Attachment I to NRC-95-0085

, Page 1

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I ATTACHMENT 1 DESCRIPTION AND EVALUATION OF PROPOSED TECHNICAL SPECIFICATION CHANGE TO

. DELETE PERIODIC TESTING REOUIREMENT FOR i

THERMAL OVERLOAD PROTECTIVE DEVICES 9

4 Attachment I to i i- NRC-95-0085

Page 2 i J

INTRODUCTION i

j The purpose of this proposed amendment is to modify Technical Specification 4.8.4.3

to delete the requirement for periodic testing of Motor Operated Valve (MOV) l thermal overload protective devices and clarify the situational testing requirement for l

Thermal Overload (TOL) protective devices.

j The specific anicle to be revised is as follows:

i j Surveillance Requirement 4.8.4.3 is being revised. Currently, a sample of TOL

! protective devices are required to be periodically tested every 18 months to assure high MOV reliability. However, as discussed below, data has been collected through

years of testing at Fermi 2 showing that the tests are unnecessary and do not improve i reliability of MOVs. Funhermore, the test themselves are the only significant cause

{ for TOL protective device degradation and actually cause an adverse effect to plant j safety as discussed later. By no longer conducting periodic tests on the TOL

protective devices, needless wear will be eliminated, thereby increasing reliability of
the component and MOVs. Also, the length of online system outages would be

). reduced. The purpose of the proposed change is to prevent degradation of TOL 4 protective devices, increase overall plant safety, and to diminish related testing costs.

i i In addition, the situational testing requirement of TOL protective devices is being

clarified. The current wording could literally require that TOL protective devices be -

tested afler any maintenance on the motor starter. However, maintenance on the

motor starter does not always impact the TOL protective devices. Thus, the
proposed change requires that the TOL protective devices be tested only following l any maintenance that could affect their performance and upon initial installation.

Technical Specification Bases 3/4.8,4 is being revised to reflect the above changes.

EVALUATION

TOL protective devices are used to protect the motors on MOVs from overload ,

conditions, up to stall condition (locked rotor currents). If a foreign object is lodged in the MOV or there is some other event that prevents the closing of the valve, the motor will be subjected to increasing heat due to the high current. The TOL protective devices break the circuit at a certain trip setpoint, thus terminating the current and protecting the motor. This is accomplished by a heater inside the TOL i protective device that uses the current to heat a bi-metallic element. At a certain '

J

temperature, the bi-metallic element will bend enough due to the heat to open control contacts, stopping current flow to the motor through de-energizing of the starter

, contactor.

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Attachment I to  !

l NRC-95-0085 '

1 Page 3 l

Under normal conditions, safety related MOV TOL protective devices are not *

! exposed to any significant amount of heat or current. This is due to infrequent operation of the motor and relatively low normal current levels. However, the a periodic TOL testing submits the TOL protective devices to prolonged exposure to i high heat and current; both are above the conditions normally experienced. The ,

j testing itself has an adverse effect on the TOL protective devices and is the only significant source ofdegradation as confirmed by maintenance history. Continuing to

  • j periodically subject the TOL protective devices to the tests could decrease their  ;
reliability. Besides the degradation of the components and decreasing reliability, the j testing presents other adverse effects to plant safety.

i In addition to degrading the TOL protective devices, another safety concern is that i the testing requires the MOV to be removed from service for approximately eleven j hours or more. Often, a single MOV removed from service will render an entire i safety system / division inoperable. Typically,40 MdVs are tested each operating 4 cycle.

l The periodic testing also creates a potential hazard to plant personnel. Due to the use i of test ovens, temporary electrical connections, and the high amperages involved in j the testing, there is a risk of burns and electric shock to personnel.

i i, NRC Regulatory Guide 1.106, Revision 1, published in March of 1977 expressed

concern related to the implementation of TOL protective devices. The concern was j that industries would take conservative methods to protect the motor instead of j completing the safety function of the MOV. Since there was little test experience at i

the time, there was a concern that the trip setpoints may drift over time. More specifically, the TOL protective devices could trip prematurely. The valve stroke i would be incomplete and the intended safety function would not be finished. The

! periodic testing requirement was initiated to make certain that the trip setpoints

would not drift over time causing premature trips. This regulatory guide was to ensure the safety and reliability of MOVs.

Although the periodic testing was beneficial by confirming that there is no non-J conservative setpoint drift over time, it has been demonstrated that periodic testing of the TOL protective devices utilized at Fermi 2 no longer provides benefit. The periodic testing does not ensure or improve the reliability of MOVs, and it is no i longer necessary. Fermi 2 has been testing the TOL protective devices in accordance with NRC Regulatory Guide 1.106, and through the course ofover 300 test evolutions, there have been only two instances of failure. In these instances, the failures were a result of trip times that were approximately ten percent above the maximum allowed. The trip times that were above the maximum allowed criteria 4

were in the conservative direction from a standpoint of plant safety because although this offers less protection for the MOV motor, the valve will have already completed s

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Attachment I to )

NRC-95-0085 l

Page 4 i i

its stroke, finishing its intended safety function. Other than the two tests in which the

trip times were greater than the acceptance criteria, maintenance history shows that
there were no degradation or failures of TOL devices other than those which were at'ributable to testing. A recent problem involving MOV thermal overloads was documented in plant Deviation Event Report (DER) 95-0926. The cause of the prob?cm was excessive heat from the TOL testing process had caused the TOL relay

! casings to crack. Additionally, in over nine years of plant operations, there has been

! no instance of a safety related MOV failure due to degradation or failure of TOL i

devices.

j A survey of four other plants that have been periodically testing TOL protective j devices provided similar supporting data.

Also, per Technical Specification (TS) Bases 3/4.8.4, the operability requirements for the thermal overload protection ensure TOL protection will not prevent safety related valves from performing their function. The TS purpose is not to ensure that the

safety related valves have thermal overload protection.

While MOV TOL devices have actuated to perform their function, there have been no

] failures or degradation of TOL devices causing failure of a safety related MOV. The

! testing proposed to be eliminated esm only detect problems with TOL devices, not

problems with MOVs leading to actuation of the TOL.

4 Continued reliability of MOVs is demonstrated per the Fermi 2 Inservice Testing Program for Generic Letter 89-10 valves. This program contains testing to demonstrate satisfactory performance of Generic Letter 89-10 globe and gate MOVs

on a periodic basis.

4

j. In addition to increasing overall plant safety, the proposed change would also save i unnecessary costs associated with the periodic testing. For example, the work hours
of the scheduled MOV maintenance activities would be reduced, which would reduce maintenance cost. The need for specific scheduling work and the time needed for i Operations personnel in the Control Room to approve the performance of the j surveillance would be eliminated. The administrative werkload would be reduced.

The cost and bulk of archival of surveillance packages would be eliminated.

! To summarize, this submittal proposes to delete the requirement for periodic testing of the TOL protective devices. This change is proposed on the basis of 1) the increase of plant safety due to the elimination for the need to remove safety related equipment from service to test TOL devices 2) the decrease in safety hazards to plant personnel 3) the increase in TOL protective device reliability due to the elimination of TOL protective device degradation,4) the documented history showing no

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1 Attachment I to NRC-95-0085 j' Page5 benefits or increased MOV reliability as a result ofperiodic testing, and 5) the

}

j reduction in costs associated with testing.

l The surveillance requirement for the situational testing of the TOL protective devices

is also being clarified. Testing will be conducted after any maintenance that could affect the performance of the TOL protective devices and upon initial installation.

i Maintenance on the motor starter may not always have an impact on the TOL

protective devices. The proposed change is to ensure that the TOL protective devices are tested only when necessary.

1 SIGNIFICANT HAZARDS CONSIDERATION In accordance with 10CFR50.92, Detroit Edison has made a determination that the proposed amendment involves no significant hazards considerations. To make this t determination, Detroit Edison must establish that operation in accordance with the l proposed amendment would not: (1) involve a significant increase in the probability

) or consequences of an accident previously evaluated, or (2) create the possibility of a i new or different kind of accident from any accident prefiously evaluated, or (3) involve a significant reduction in a margin of safety. The proposed amendment will delete the surveillance requirement for periodic testing of TOL protective devices and j clarify the circumstances when TOL testing will be conducted.

> 1. The proposed change does not involve a significant increase in the probability or

, consequences of an accident. The deletion of the requirement for testing of the

TOL protective devices lessens degradation to the components which can 3 improve MOV reliability. Based on historical data through the years of testing, there is no significant drifling of the trip setpoints of the TOL protective devices.

The probability of an accident would not increase since terminating the periodic

testing or clarifying the situational testing requirements cannot cause equipment to operate inadvertently and so cannot cause an accident. The periodic testing of the TOL protective devices can temporarily render MOVs inoperable due to the
removal of the components from service and can cause safety systems / divisions to become unavailable. The deletion of the periodic testing requirement would
increase the availability of safety systems insuring that they would be able to respond to accident conditions. The consequences of an accident will not increase since eliminating the periodic testing and clarifying the situational testing requirements will improve reliability of safety-related MOVs to respond to an accident and will not increase the failure rate of equipment. The clarification of I

the situational testing ensures that the test will be conducted after any maintenance that could affect the performance of the TOL protective devices.

Thus, the proposed change increases reliability of the MOVs and increases plant safety. Therefore this change will not result in a significant increase in the )

probability or consequences of an accident.

Attachment I to NRC-95-0085

. Page 6 3

2. The proposed change does not create the possibility of a new or different accident
from any previously evaluated. The TOL protective devices are not an accident j initiator, they only protect equipment provided to mitigate the consequences of an accident. For this reason, no new or different type of accident is created by this .

i change.

3. The proposed change does not involve a significant reduction in a margin of
safety. The trip setpoints of the TOL protective devices depend upon both the

, current and the length of time the current is applied. The trip setpoints for TOL protective devices are much higher than conditions normally experienced during an MOV stroke and are meant to protect the motor from stall and overload conditions. The difference between the current of the trip setpoints and the

normal conditions is great enough that a premature trip of the TOL protective device is highly unlikely, even at degraded voltages. The TOL protective device protects the motor from the stall conditions. Not conducting the periodic testing i of the TOL protective devices would not cause the MOVs to fail, nor would the performance of the MOVs be adversely affected. Throughout the life of the plant, there has never been an instance of a safety related MOV failure due to
degradation or failure of TOL protective devices. Further, based on maintenance l history, the elimination of the periodic testing would eliminate any significant potential degradation of the TOL protective devices, thereby increasing their
reliability. Finally, with the removal of the periodic testing of the TOL protective  ;

~; devices, fewer MOVs would have to be removed from service for testing. Since necessary components would no longer be inoperable due to the periodic testing, 4

there would be an increase of availability time of safety systems / divisions.

Deletion of the periodic testing could reduce the durations of online system outages. Clarifying the situational testing requirements would better define when the testing of the TOL protective devices is necessary which would ensure operability. The testing would be based on installation or any maintenance that l could affect the TOL protective device. For these reasons, the proposed change

! does not involve a significant reduction in the margin of safety.

ENVIRONMENTAL IMPACT ,

^

Detroit Edison has reviewed the proposed Technical Specification changes against the criteria of 10CFR51.22 for environmental considerations. The proposed changes do not involve a significant hazards consideration, nor significantly change the types or j increase the amounts of effluents that may be released offsite, nor increase individual l or cumulative occupational radiation exposures. Based on the foregoing, Detroit Edison concludes that the proposed Technical Specifications meet the criteria given in

, 10CFR51.22(c)(9) for a categorical exclusion from the requirements for an Environmental Impact Statement.

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. o Attachment I to NRC-95-0085 Page 7 CONCLUSION Based on the evaluations above: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's -

regulations, and the proposed amendment will not be inimical to the common defense and security or the health and safety of the public.

Detroit Edison requests that the proposed license amendment be effective within 60 days of approval by the Commission.

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