ML20212P689

Forwards Justifications for Continued Operation for butyl- Rubber & Polyethylene Insulated Cables,In Response to Concerns Resulting from Environ Equipment Qualification Insp During Wk of 860915

ML20212P689
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	03/06/1987
From:	Bordine T CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 8703160200
Download: ML20212P689 (12)

Text

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MMM&q M oeneral off6ces: 1946 West Parnell Road, Jackson, MI 49201 . (517) 788 0550 March 6, 1987 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT -

JUSTIFICATION FOR CONTINUED OPERATION FOR BUTYL-RUBBER AND POLYETliYLENE INSULATED CABLES During the week of September 15, 1986, the NRC conducted an Environmental Equipment Qualification inspection at Big Rock Point. The results of this inspection are documented in NRC IE Inspection Report 86013 dated November 4, 1986. One of the concerns identified in the inspection report involves environmental qualification of Butyl-rubber and polyethylene insulated cables installed at Big Rock Point. As documented in the inspection report, this concern was to be forwarded to NRR for further review and resolution. The principal issue regarding cable qualification was the need to establish similarity between cables described in qualification test reports and those actually installed at Big Rock. The report cited four EEQ files which were inadequate. These four files cover two types of cable insulations Butyl-rubber with a PVC jacket and polyethylene with a PVC jacket.

As a result of meetings at the NRC on March 3 and 4, 1987, to discuss the resolution of cable qualificatien issue, Consumers Power Company committed to submit justifications for continued operation (JCos) for the specific EEQ components which rely on these cable types prior to startup from the current refueling outage and to submit a long-term proposal to resolve the cable concern within 30 days of startup. This submittal provides the JCOs.

In order to strengthen the similarity portion of these files, original plant construction records were searched subsequent to the inspection. Field purchase orders, manufacturers' certificates of compliance, and material test reports were found that provided a complete description of each purchased cable. "'s cable descriptions and specifications are consistent for all purchase orders regardless of manufacturer. On many purchase orders and manufacturers' documents, standards are referenced as a specification requirement.

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. Nuclear Regulatory Commission 2 Big Rock Point Plant Justification for Cont Oper - Insulated Cables March 6, 1987 The qualification reports in the subject EEQ files also provide detailed descriptions of tested cables which closely match the materials, insulation thickness and jacket thickness contained in plant records. We believe this documentation provides sufficient evidence to conclude the cables are of similar construction.

Our correlations indicate that insignificant deviations exist in the manufacturing of these types of cable insulation. The effort was based on the June, 1984. NRC EEQ audit report which stated certain cables should be tested or a more positive effort to show qualification through testing already completed should be initiated. Consumers Power Company believes the present qualification status represents a positive effort as required by the June, 1984, NRC audit report. Qualification reports for cable made of similar material were obtained. Our similarity evaluation is based on information available in the original procurement documentation.

Comments made by the NRC staff during the March 3-4, 1987, meetings revealed that cable similarity arguments would necessarily have to establish that identical materials and construction methods were employed. This impasse resulted in a Consumers Power Company commitment to provide additional JCOs for specific EEQ components which rely on these cable types. Because our qualification effort was based on an option which has subsequently been eliminated, Consumers Power further committed to study the remaining options available to resolve this issue. The results of this study will be provided to you by letter in 30 days.

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ATTACHMENT Consumers Power Company Big Rock Point Plant Docket 50-155 JUSTIFICATIONS FOR CONTINUED OPERATION FOR COMPONENTS UTILIZ1NG BUTYL-RUBBER AND POLYETHYLENE INSULATED CABLES March 6, 1987 9 Pages OC0387-0006A-NLO2

1 Attachment Consumers Power Company believes that the existing EEQ files for the Butyl-rubber and polyethylene cables adequately demonstrate that the cables in use will perform their intended safety functions following exposure to a harsh environment. These qualification files in themselves provide justification for continued plant operation until similarity concerns are resolved, however, functional JCOs are also provided.

The following safety systems needed to mitigate a loss of coolant accident contain cables with the Butyl-rubber and polyethylene insulation under discussion.

• Reactor Protection System

• Containment Isolation System

• Primary Enclosure Spray Actuation

• Primary Core Spray System

• Post Incident Cooling System

• Back-up Enclosure Spray JCOs for these systems were written based upon the JCOs provided to the staff during earlier phases of the EEQ effort.

Consumers Power concludes that this information provides justification for continued operation of Big Rock Point while resolving the similarity concerns and that no unreviewed safety question exists.

PRIMARY ENCLOSURE SPRAY SYSTEM This system automatically actuates the primary enclosure spray valve M0-7064 if containment building pressure exceeds 2.2 psig. Cables which are made of the subject Butyl-rubber and polethylene insulation material serve two devices, PS-636 and PS-637, within this system. These devices are located in the Outside Penetration Room. Post accident conditions for this room are:

1 hr 30 day Radiation dose 8.9 x 103 1.25 x 105 Temp 60-80*F Max Temp 140*F at 100 hrs Normal AMB No other parameters apply to this area.

As discussed in the Consumers Power Company submittal dated March 15, 1982, enclosure spray is required to mitigate the effects of large steam line breaks. For these breaks, spray actuation occurs at approximately 75 seconds into the event. The pressure switches actuate the enclosure spray valve.

Justification for continued operation for these circuits utilizing these cables in based on the following:

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. 2 Attachment A. The equipment'will have performed its safety function prior to failure. With enclosure spray occurring in a short time period after the LOCA, and the cables seeing only limited exposure to the harsh environment, failure prior to actuation is very remote.

B. The plant can be safely shut down in the absence of the cables.

Should the containment pressure rise, the operator can manually.

initiate enclosure spray with circuits not located in a harsh environment.

CONTAINMENT ISOLATION ,

i Containment Isolation occurs on three monitored parameters at Big Rock Point; low reactor vessel level, high containment pressure, or loss of power. As discussed in our March 15, 1982 submittal, for large and intermediate size breaks, reactor low level is reached prior to one minute. For small breaks reactor low level is not reached until up to 45 minutes, however, the isola-tion function is actuated by the containment high pressure within 100 seconds.

Using the above, the following justifications are made with respect to the Containment Isolation schemes containing cable of polyethylene or Butyl rubber insulation construction.

1. The Containment Isolation paths for the containment clean and dirty sump discharge and fuel pool drain lines each contain two air operated control valves, one on each side of containment. The control valves are actuated by solenoid valves which manipulate control air to open or close the control valves. Position switches are also included on each valve.

Containment isolation Path: Clean Sump Discharge Inside Outside CV-4031 Control valve (in process path) CV-4102 SV-4869 Solenoid valve SV-4895 POS-6624 Position switch POS-6628 Containment Isolation Path: Dirty Sump Discharge Inside Outside CV-4025 Control valve (in process path) CV-4103 SV-4891 Solenoid valve SV-4896 i

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electrical' power cause the isolation valves to,elosa.

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, cables /for' equipment in'ide s containment. However,'outsid's containment in the steam tunnel area .where redundant equipment is located, the immediate

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! A. The equ'1pment will have perforiad its.safetyffundtiva prior,to failure.' With Containment Isolation occurring in n'short time period f

p. af ter ehe cLOCA, the, equipment i,ees" only' limite.d exposure to, ':he harsh '

j envirorasent und failsre prio to actuation is very remote.

B. Redundant equipment is,.evailable to substitute for a failure of the

, ,f components located inside; cont %inment.

2. The,$<sttainment Isolation,. piths for the treated waste return, demineral-ized water, and clean-up' resin slu b lines each contain one dir operated

' controi valve and. either a check valv's or normally closed manual valve.

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8 Inside Outside j s CV-4049 Control valve (in process path) Check W lve

, SV-4892 Solenoid volve POS-6626 Position switch i

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4 Attachment-1 Containment Isolation Path: Domin Water Inside Outside Check Valve Control valve / (in process path) CV-4105

' Solenoid valve SV-4897 Position switch POS-6649 These schemes are of " fail safe" design in that loss of control air or electrical power cause the contro1' valves to close. -Additionally, the check valves and manual valve perform their safety,functioh without.

electrical components.

The resin sluice line control v'alves and the manual L' solation valve are normally closed per procedure during power operation except in the case of transferring resins., In the remote event that a break occurred during

-the time resins were being transferred, the qualified solenoid valves

- will perform their isolation function. The only portion of this scheme

-containing cables of polyethylene or Butyl-rubber is the position indica- .

tion.

The treated waste return and demineralized water lines contain self-actuating check valves for performing the isolation function. Even if it is assumed that extended exposure to the harsh environment caused failure of the polyethylene or Butyl-rubber cables containment isolation is assured. 4 Justification for continued operation for these circuits utilizing cable of Butyl-rubber and/or polyethylene insulation is based upon the t following:

1 A. The equipment will have performed its safety function prior to '

failure. . With ccatainment isolation occurring in a short time period after'a LOCA, the equipment sees only limited exposure to the harsh t 2

environment and failure prior to actuation is very remote. Per procedure, operators check position indication immediately following isolation actuation.

.B. Redundant equipment (check valves or manual valve) not depsudent on electrical operability are available to perform the isolation function.

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3. The Containment' Isolation path for the containment ventilation supply and exhaust air lines each contain two air operated. control-valves, both outside of containment. The control valves are activated by solenoid valves which manipulates control air to open or close the valve.

Position switches are also included on each valve.

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Solenoid valve SV-9154 POS-9103 Position switch _ -POS-9104 I- In' addition to the containment isolation function, these valves may also o N. be required to reopen to accomplish the vacuum' relief function during the post-LOCA period when containment sprays are actuated to condense the steam pressure environment incide centnin=ent. Contcinment sprey is iz actuated at a containment pressure of 2.2 psig which as discussed in our

! March 15, 1982 submittal occurs at approximately 75 seconds into the event. ,

This equipment and the_ subject cables are located outside containment and l subject to normal ambient temperature, pressure, and relative humidity prior to at.d following a LOCA. Radiation exposure during the 30 day piriod following a-LOCA will only be 2.48 x 104 rads and occurs after the components have performed their safety function, i

I Justification for continued operation for these circuits using cable of

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Butyl-rubber and/or polyethylene insulation is based upon the following:

A. The equipment will have performed its safety function prior to I failure. With containment isolation and vacuum-relief occurring in a l: short time period after a LOCA, the equipment sees only limited I ' radiation exposure and a aormal thermal environment and failure prior

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to acccmplishing these function is very remote.

PRIMARY CORE SPRAY

This system automatically actuates the primary core spray valve operators upon

receiving low reactor water level and low reactor pressure signals. Cables l which are made of the subject Butyl-rubber and polyethylene insulation

! material serve the level switches LS-RE09A through D and pressure switches l PS-IG11A through D. .These devices are located inside the Reactor Building.

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1*. 6 Attachment As discussed in the March 15, 1982 submittal, core spray activation occurs-within 2-5 minutes following large and intermediate size breaks. For small breaks, core spray occurs up to 45 minutes following the. event, however, due I to the. limited size of the break, containment atmospheric conditions are

.significantly less than design parameters until RDS actuation. The justifica-tion for continued operation with the subject cables installed is based on the following:

A. A redundant fully qualified, back-up core spray system (M0-7070 &

MO-7071) is available to substitute for the assumed failures in the primary spray system.

B. Based upon the actuation times and environment at time of actuation as discussed above, the equipment will perform its safety function prior to failure.

C. Since the suspect cables are only used in the automatic actuation circuita for the core spray systems the plant can be safely shut down in the absence of the cables by manually initiating primary core

spray. The ability to reclose the valves is not affected by a

failure in the s,uspect cables, an action which may be necessary when entering the recirculation mode.

REACTOR PROTECTION SYSTEM (RPS)

As discussed in our March 15, 1982 submittal, RPS actuation can occur from the following monit':ed. parameters during LOCA events:

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• Low Steam Drum Water Level

• Low Reactor Vessel Water Level l

• High Containment Pressure l

• Loss of Power i

Reactor. Protection System actuation occurs very shortly following a LOCA event. For large and intermediate size breaks, reactor low level is reached l

< prior to one minute. For smaller breaks, scram is actuated by high contain-l ment pressure within 100 seconds.

The following RPS component schemes use cable of polyethylene or Butyl-rubber i insulation

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• Control Rod Drive Scram Solenoids (SV-NC22's & SV-NC-27's)

• Main Steam isolation Valve (MO-7050) Limit Switch

• Low Reactor Level Switches (LS RE09 A-D)

• High Containment Pressure Switches (PS-664-7)

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.The scram solenoids are of " fail safe" design and are de-energized on RPS actuation. For automatically initiated scrams, these solenoids are de-energized befora the containment environment becomes very harsh, Even under the assumption that the cable to the solenoids fails (open or short circuit), this results in a loss of power to the solenoids and a reactor scram.

Justification for continued operation is based on the following:

A. The cables / components will have performed their safety function prior to failure. RPS actuation occurs within one minute following a break event and with limited exposure to the LOCA cnvironment in this short period, failure prior to actuation is very remote.

B. The plant can be safety shut down in the absence of the cables and components based upon the " fail safe" design which initiates reactor scram on an assumed failure of the cable.

The main steam isolation valve (MO-7050) limit switch initiates RPS actuation for load rejection transients and not LOCA events. A failure of the cable (open or short circuit) between the Ibnit switch and RPS will not prevent a reactor scram from occurring _during a LOCA event. Justification for continued operation is based upon the fact that the plant can be safely shutdown in the absence of the cables (assumed failure) in this scheme.

The low reactor water level, and high containment pressure circuits initiate RPS actuation (scram and containment isolation) during LOCA events. In addition, the low steam drum water level schemes are the first to initiate reactor scram during LOCA events. The sensor's contact opens on an initiating signal to actuate the RPS.

During LOCA events, actuation of these circuits occurs very early. Although not discussed earlier, the low steam drum level setpoint is reached much earlier than the low reactor level setpoint. Due to these early actuation times, the cables / components in these schemes do not experience the harsh environment prior to actuation. In addition, the containment high pressure switches and cabling are located outside of containment in the Electrical Penetration Room. Justification for continued operation is based on the following-A. The cables / components will have performed their safety functions prior to failure. RPS actuation occurs within 1 minute following a break event and with limited exposure to the environment in this short period, failure prior to actuation is very remote.

B. The plan can be safely shut down in the absence of the cables and components. Assuming failure of the cables in the sensor circuits, manual initiation of the RPS can occur in the Control Room on circuits not subjected to harsh environments.

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8 Attachment BACKUP ENCLOSURE SPRAY The back-up' enclosure spray' valve is manually actuated following a failure of the primary enclosure spray valve to open. As discussed in our March 15, 1982 submittal, the need for enclosure spray occurs for large steam line breaks.-

Ihe primary enclosure spray valve actuates within 75 seconds of the event.

Should the unlikely failure'of the primary enclosure spray valve occur at this time, the back-up spray would be manually actuated immediately.

Within this system, cables going to the back-up enclosure spray operator are i made of_the subject Butyl-rubber insulation material. Our submittals dated  !

September 19, 1986 and October 10, 1987 provide a detailed description of these spray systems and a justification for continued operation with M0-7068 l EEQ documentation inadequate. Although this valve operator has been replaced with a fully qualified operator, the JC0 can be used for this cable issue as well. Thus justification for continued operation can be summarized as follows:

~A. Another system (primary enclosure spray valve) is capable of j providing the required safety function. Although the primary spray '

valve has suspect cable in its actuation circuit, it can be manually initiated to accomplish the safety function.

l B. The equipment will perform its safety function prior to failure.

Since the valve is actuated shortly after a LOCA with limited cable exposure to the environment in this short period, failure prior to l actuation is unlikely. Should the valve fail open af ter actuation l the ability to furnish adequate core spray flow will not be jeopardized as discussed in the September 19, 1986 submittal.

C. The plant can be safely shut down in the absence of the cables. The unique function of the back-up enclosure spray is to provide post-accident iodine washdown. Failure to accomplish this function due to the changes made in operating procedure EMP 3.3 as described in the September 19, 1986 letter will not prevent safe shutdown of the plant. The EMP 3.3 changes will remain in place until the cable issue is resolved.

POST INCIDENT COOLING SYSTEM This system uses fire water to cool the containment sump water which is then recirculated by the core spray pumps back to the reactor vessel to establish

-long term cooling. Cables which are made of Butyl-rubber and polyethylene insulation material serve a valve motor operator (MO-7066) and the core spray pump motors. All the components in this system are manually initiated from the Control Room and are all located in the Core Spray Equipment Room which is located outside of and shielded from containment. Post accident conditions for this location are:

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Attachment Radiation dose (30 day) 4.29 x 10 4R Temperature (maximum ambient) 169'F No other parameters apply to this area.

Based upon the above, continued operation is justified as follows:

A. The equipment / cables will have performed their safety function prior to failure. As discussed, the accident conditions are not very harsh ,

and failure of the cables under these conditions is not expected.

B. For an assumed failure of the cables to M0-7066, a fully qualified redundant system, M0-7080, 10 capable of providing cooling water to the core spray heat exchanger.

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