ML20085J953

From kanterella
Jump to navigation Jump to search
Requests Enforcement Discretion Re TS LCO Re Div 2 DC Electrical Power Sources
ML20085J953
Person / Time
Site: Clinton Constellation icon.png
Issue date: 02/16/1995
From: Jackie Cook
ILLINOIS POWER CO.
To: Martin J
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20085J955 List:
References
JGC-084-95, JGC-84-95, NUDOCS 9506230094
Download: ML20085J953 (8)


Text

w,,

4thnois Powar CompIny Chnton Power Station -

P.O. Box 678 Chnton. IL 61727 Tel 217 935-5623 Fan 217 935 4632 John G. Cook i Vice Presdent  !

P(uWER u.602420 L47-95( 02 - 16 )LP 8E.100a JGC-084-95 Docket No. 50-461 February 16,1995 Mr. L B. Martin Regional Administrator, Region III /

U.S. Nuclear Regulatory Commission 801 Warrenville Road

[jh/ '

Lisle, Illinois 60532-4351

Subject:

Request for Enforcement Discretion Regarding Technical Specification Limiting Condition for Operation Related to Division 2 DC Electrical Power Sources  :

Dear Mr. Martin:

Events have occurred at Clinton Power Station (CPS) which require your prompt attention as Illinois Power (IP) requests enforcement discretion regarding the Technical Specification Limiting Condition for Operation specified for the Division 2 DC electrical power sources. Due to a failure of the Division 2 battery charger that occurred at 7:40 a.m. February 16,1995, Action A.1 of Technical Specification 3.8.4 has been entered. Action A.1 requires that if an inoperable Division 2 DC source (i.e., battery charger) cannot be restored to operable status in 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, then the plant is to be in Hot Shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. IP is specifically requesting that enforcement discretion be granted with respect to the requirement to restore the battery charger in 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> as specified in Required Action A.1 of CPS Technical Specification 3.8.4, as IP desires additional time to effect replacement and subsequent testing of the battery charger.

In order to replace the battery charger and perform the required post-maintenance testing, more time is required than pennitted in the Action Statement of Technical Specification 3.8.4. Therefore, IP requests enforcement discretion to allow for an additional 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to restore the Division 2 battery charger to operable status. I Consistent with this request, IP requests that the Division 2 battery charger be allowed to j remain inoperable until 9:40 a.m. on Febmary 17,1995 before the plant would enter the 12-hour Hot Shutdown requirement of Technical Specification 3.8.4, Required Action C.I. If this request is not approved, CPS must be in at least a Hot Shutdown  ;

condition by 9:40 p.m. on February 16,1995.  !

i O 1 /

II

c. -

A sJ g 8 0

h e

I A

cluiu t %% ews %s  % & g ,

N o ^1t *  % t\%bw %bs accWA (so-H,h, 3%% ,

a%R en W

e

U-602420 Page 2 4

A more detailed description of the condition, including the circumstances surrounding the event, an evaluation of the safety significance, justification for this request, and a discussion of why this request does not involve a significant hazards consideration is provided in Attachment 2 of this letter. Copies of the relevant portions of CPS Technical Specification 3.8.4 are provided in Attachment 3 for reference. In addition, an aflidavit supporting the facts set forth in this letter and its attachments is provided in Attachment 1.

IP has reviewed this request against the criteria of 10CFR51.22 for categorical exclusion from environmental impact considerations. The request does not involve a significant hazards consideration, or significantly increase the amounts or change the types of effluents that may be released offsite, nor does it significantly increase individual or cumulative occupational radiation exposures. Based on the foregoing, IP concludes that the proposed request meets the criteria given in 10CFR51.22(c)(9) for a categorical exclusion from the requirement for an Environmental Impact Statement and also therefore, does not involve irreversible environmental consequences.

This request has been reviewed by the CPS Facility Review Group and they have determined that it does not constitute an unreviewed safety question.

Sincerely yours, b

.G. Cook ice President TAB /csm Attachments .

l cc: NRC Clinton Licensing Project Manager NRC Resident Office, V-690 l

Illinois Department of Nuclear Safety l

l l

I l

Attachment I to U-602420 J. G. Cook, being first duly sworn, deposes and says: That he is Vice President ofIllinois Power; that this request for Enforcement Discretion has been prepared under his supervision and direction; that he knows the contents thereof; and that to the best of his knowledge and belief said letter and the facts contained therein are true and correct.

Date: This /b day ofFebruary 1995 Signed:

J.G. Cook STATE OF ILLINOIS l SS.

f '

D0dfr COUNTY J Subscribed and sworn to before me this /6 0 day ofFebruary 1995.

r:::::::::::: ,,,,,,,,, _

' OFFCIAL S2AL ' J s -c '

nnothy A Br.m !W~

~' ~

Noh7 Pde S;;;3 cf Brenots ot Publ'c)

%r com
cca,Wes 11/207 ;

': :::: ::. .~. ~ n.,,, _,;;

Attachment 2 to U-602420 Page1of5 Description of Condition / Reason for Request On February 16,1995 at approximately 7:40 a.m., it was determined that the Division 2 battery charger had failed. As a result, the battery charger was declared inoperable and the associated Actions of the Clinton Power Station (CPS) Technical Specifications (TS) were entered.

The operability requirements (during Modes 1,2, and 3) for the Division 2 battery charger, including the actions to be taken if the Division 2 battery charger is inoperable, are specified in CPS Technical Specification 3.8.4. (See Attachment 3 of this submittal.)

R equired Action A.1 requires that with the Division 2 DC electrical power source inoperable, the inoperable DC source must be restored to operable status within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

If the inoperable DC source cannot be restored within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, the plant must be in Mode 3 within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in Mode 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

Based on the troubleshooting completed to date, it has been determined that the malfunction of the charger can be attributed to a failure of the firing card associated with the silicon-controlled rectifiers in the "C" phase of the charger. Replacement of the failed firing card was initially considered as a fix, however, due to uncertainties as to the root cause of the card failure and the fact that there are no spare cards available on site, it was decided to replace the entire charger with a spare charger. The replacement charger has been tested in the shop and functions properly. It is expected that replacement and testing of the charger will take approximately 12-16 hours.

pescription/ Sequence of Work to be Performed IP intends to replace the failed Division 2 battery charger with a spare charger. While the charger is being replaced, the Division 2 bus (IB) is being powered by the Division 2 battery. Non-essential loads have been shed from the IB bus and the Division 2 battery is currently discharging at a rate of 8 amps. It is expected that it will be in excess of 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> before the battery voltage will drop below 105 volts which is the rated voltage of the battery and the minimum voltage required to support operation of the associated DC loads. Once the replacement charger is installed and connected to the subsystem, a load test will be performed in accordance with CPS Technical Specification surveillance requirement (SR) 3.8.4.6. Following the load test, the charger will be returned to service, and providing the Division 2 battery meets its Technical Specification limits, the Division 2 DC electrical power supply subsystem will be restored to operable status. The charger will then be monitored to ensure there are no additional problems. IP currently estimates that this work may take up to an additional 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> beyond the required 12-hour shutdown statement. To support completion of this work, IP requests a 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> extension of the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> completion time for TS 3.8.4 Required Action A.I.

i l

  • ~ '

Attachment 2 to U-602420 Page 2 0f 5 1 Justification for Proposed Reauest As described in USAR Section 8.3.2, the DC power system provides DC control and 1 motive power for vital equipment during normal as well as emergency conditions of the l plant. The safety-related DC power system consists of four Class IE,125-volt DC  ;

subsystems [each with its own Motor Control Center (MCC), distribution panel, charger, j and accessory equipment). They are electrically isolated and physically separated so that i any failure involving one source cannot jeopardize the function of the other source.

l The system design allows for the single failure or loss of any redundant DC subsystem -

during simultaneous accident and loss of offsite power conditions without adversely affecting safe shutdown of the plant. Only Division 1, Division 2, and Division 3125-volt DC subsystems are required to be considered for safe shutdown analysis of the plant.

During normal operation the 125-volt DC bus voltages are maintained and the divisional batteries are kept fully charged by battery chargers. The 125-volt DC MCCs and each of i the 125-volt DC distribution panels normally are fed from their primary (charger) and secondary (battery) sources operating in parallel in a " float-charge" configuration. For  ;

each Division 1, Division 2, and Division 4 DC power system (the Division 3 design is -  !

slightly different and is not affected by this request), an ammeter and a voltmeter are provided in the main control room to monitor the battery charge / discharge current and DC  !

i bus voltage, respectively. DC bus undervoltage, bus grounding, opening of the battery or battery charger breakers, and charger trouble alarms are also provided in the main control  ;

room. A DC bus high voltage condition is monitored by the bus voltmeter. High ,

discharge rate of the battery is monitored through the ammeter.

i With respect to the current status of other systems at CPS important to safety, only the Division 2 battery charger and inverter remain out of service at this time (as of Febmary 16,1995). All essential loads on the Division 2 DC bus remain energized. The ' .

Division 1,3, and 4 DC electrical power subsystems are operele and there have been no  ;

indications of problems with any of the other chargers. No systems or equipment important to safety which are associated with the redundant safety-related division (Division 1 and 3) will be removed from service for planned maintenance or testing during the extended time interval. t f

Regarding the need for maintaining the plant on-line, CPS is presently supportmg -

approximately 22 percent of the total electrical IP customer load. It is estimated, ,

however, that ifCPS must shut down, IP can only meet demand by purchasing ,

approximately 500 MW electric of replacement power. Notwithstanding the current load  !

demand, IP wishes to avoid an unnecessary plant shutdown as further described in this [

submittal.

l i

f

--+s'_ 1-_- s__-- _ _ - - - - - - . - - - , - - - _ . - . - - _ . _ _

~' '

Attachment 2 to U-602420 Page 3 of 5 Compensatory Actions As stated above, the Division 2 bus is currently being energized by the Division 2 battery.

All essential loads continue to be powered (with the Division 2 inverter being supplied by its alternate AC power source which is capable of being powered by the Division 2 diesel generator) and it is expected at the current rate of discharge, the battery will continue to provide this load for at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />.

A plant shutdown was begun within the time requirements of Technical Specification 3.8.4. At 1:15 p.m. an Unusual Event was declared in accordance with the CPS Emergency Plan as a result of reducing reactor power as required by the TS. The intent is to lower the reactor power level to approximately 65%. This is intended to support shutdown to Mode 3 in a timely manner ifit is determined to be necessary. If following the charger replacement it fails to function properly, if Division 2 voltage drops to unacceptable levels, if the time extension permitted by enforcement discretion runs out or if a problem develops with one of the other divisions of DC power, IP will continue to bring the plant to Hot Shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Cold Shutdown in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

Division 1, 3, and 4 DC electrical power subsystems will remain operable during the time required to replace the Division 2 battery charger. No equipment will be taken out of service during this time to limit the potential for a plant transient.

Safety Sinnificance/ Basis for No Significant Hazards Consideration IP does not consider this request to be safety significant in view of the following:

1

1) With respect to safety-related DC power, only the Division 2 battery charger is currently inoperable. Additionally, during this time period, the Division 2 inverter is inoperable because it's power supply was transferred to the alternate AC feed (which is capable of being supplied by the Division 2 diesel generator). Per CPS i TS 3.8.7, the power supply to the Division 2 inverter must be restored to the IB  !

bus within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (i.e., by 0945 hours0.0109 days <br />0.263 hours <br />0.00156 weeks <br />3.595725e-4 months <br /> on February 17,1995). All remaining loads fed by the IB bus will remain operable as a result of being fed by the Division 2 battery. Because offsite power and the remaining divisions of DC l power are available, sufficient redundancy exists to provide DC power to systems required to mitigate the consequences of an accident. In addition, at the current rate of discharge, the Division 2 battery will provide sufficient DC power for the l

current IB bus loads for at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />.

2) Generally, operation under the provi.; ions of an Action Statement is permitted for  ;

limited periods of time. It is recognized that single-failure criteria may not be met i during such operation. IP believes that operation with the Division 2 battery

~~

Attochment 2  :

i to U-602420 Page 4 of 5 charger out of service for a period of time longer than normally allowed but within the requested time limit constitutes no significant increase in risk regarding the safe operation of the facility.

3) In addition, IP does not believe that the present situation should require subjecting the plant to an unnecessary shutdown. Although there is certain risk associated r with the increased allowed out-of-service time, most challenges to plant systems (i.e., increased potential for plant transients or disturbances) occur during startup and shutdown evolutions. Eliminating the risk associated with these events by preventing an unnecessary plant shutdown due to the current Action time limit, is viewed to be a positive increase in plant safety.
4) With respect to executing a safe shutdown of the plant if required, the plant design is such that safe shutdown to a cold condition can be achieved with Division 2 DC power unavailable. Safe shutdown of the plant is not compromised by this request, particularly in view of the operability of all redundant power sources and the operable status of Division I systems important to safety. Further, the remaining capacity of the Division 2 battery will ensure that the Division 2 components ,

receive the necessary DC power to ensure they will be available for at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> at the current bus loading.

According to 10CFR50.92, a proposed change to the license (Technical Specifications) involves no significant hazards consideration if operation of the facility in accordance with the proposed change would not: (1) involve a significant increase in the probability or consequences of an accident previously evaluated, or (2) create the possibility of a new or different kind of accident from any accident previously evaluated, or (3) involve a significant reduction in a margin of safety. This request is evaluated against each of these criteria as follows.

1) As noted above, the proposed one-time request would permit the Division 2 battery charger to be out of service for a longer period of time than normally allowed by the Technical Specifications. However, in view of the operability of all other required on-site DC sources and all required AC sources, IP believes that the proposed request does not constitute a significant increase in risk with respect to the capability of safety systems to mitigate the consequences of an accident.

Additionally, the proposed request would permit a reasonable amount of time to restore the Division 2 battery charger to an operable condition while avoiding an unnecessary plant shutdown and potential challenges to safety systems. Therefore, l the proposed request does not involve a significant increase in thi probability or l consequences of any accident previously evaluated. l l

=-

j

. q. .

3 -;

1 Attachment'2 -

to U-602420  !

Page 5 of 5 j

. . . -t

/ 2) The proposed request does not involve any changes to the design or operation of. l the plant. Since no new failure modes are introduced by the proposed request, the - j proposed request does not create the possibility of a new cr different kind of 1 accident from any accident previously evaluated.

3)- The Technical Specifications permit a reduction in the number of DC sources for a limited period of time. Under the proposed request, the allowed out-of-service j time for the Division 2 batterycharger (although longer than normally allowed)  :

would still be limited to a reasonable period of time. With the Division 1,3, and 4 -l DC sources operable, the proposed change does not involve a significant reduction  !

in the margin of safety normally ensured by the Technical Specifications with_ -i respect to the availability ofDC sources. Further, adequate DC power to the L 3 Division 2 equipment will be assured for at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> at the present loading.  !

1 Based on the foregoing, IP has concluded that this request does not involve a significant '

hazards consideration.

-l i

t I

l i

l 1

l 1

i