B12337, Requests Approval to Defer Completion of Switchgear Room Halon Sys Mods to 1987 Refueling Outage or First 8-wk Outage Commencing After 870101.Performing Mods During Operation Could Have Significant Impact on Sys & Components

Requests Approval to Defer Completion of Switchgear Room Halon Sys Mods to 1987 Refueling Outage or First 8-wk Outage Commencing After 870101.Performing Mods During Operation Could Have Significant Impact on Sys & Components

ML20214U888
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	11/24/1986
From:	Opeka J CONNECTICUT YANKEE ATOMIC POWER CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
B12337, NUDOCS 8612090441
Download: ML20214U888 (7)

Text

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CONNECTICUT YANKEE ATOMIC POWER COMPANY BERLIN, CONNECTICUT P o DoX 270 HARTFORD CONNECTICUT 06141-0270 November 24,1986 Docket No. 50-213 B12337 Of fice of Nuclear Reactor Regulation Mr. H.R. Denton, Director U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:

Haddam Neck Plant Fire Protection Modifications Switchgear Room Halon System INTRODUCTION In August,1986,(1) the NRC Staff granted the Connecticut Yankee Atomic Power Company (CYAPCO) an exemption from the schedular requirements of Section 50.48 in response to CYAPCO's request dated March 7,1986.(gp J The CFR granting of this exemption was made contingent gn implementation of the commitments in CYAPCO's letter dated July 3, 1986,13) which resulted from the fire protection inspection and audit of June 16-20, 1986, and submittal of a detailed implementation plan including major milestones, which was submitted to the NRC Staff September 30,1986.(4) project In a letter dated August 19, 1986,(5) CYAPCO responded to the action items of the July 3,1986 letter resolving a number of issues and cominitting to completing the remaining items by January 1,1987. With one exception, all action items required to be completed by January 1,1987 are progressing as planned to meet this completion date. The one item that will not be completed by January 1,1987 is the modification to the Switchgear Room Halon System. The purpose of this letter is to request written NRC approval of our decision to defer completion of the (1) 11. R. Denton letter to 3. F. Opeka, dated August 25,1986, " Fire Protection Exemption - Haddam Neck Plant."

(2) 3. F. Opeka letter to C. I. Grimes, dated March 7,1986, " Fire Protection -

Schedular Exemption."

(3) 3. F. Opeka letter to C. I. Grimes, dated July 3,1986, " Action items Resulting From Inspection of lladdam Neck on June 16-20, 1986."

(4) 3. F. Opeka letter to C.1. Grimes, dated September 30,1986, "Haddam Neck Plant Major Implementation Milestones New Switchdear Building Construction."

(3) 3. F. Opeka !ctter to C.1. Gritnes, dated Audust 19,1986, "Haddam Neck Plant \,

Action items Resulting Frorn Appendix R Inspection of June 16-20, 1986."

i0 8612090441 DR 861124 p ADOCK 05000213 PDR

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modifications to the Switchgear Room Halon System to the 1987 refueling outage or the first outage of at least eight weeks duration commencing after January 1,

1987. This request is being directed to your attention in accordance with Secti 9 n IV, paragraphs 2 and 3, on page 6 of the exemption dated August 25, 1986.L!)

SUMMARY

CYAPCO's review of the acceptance test data for the Switchgear Room Halon System revealed that the acceptance test criteria did not meet the current NFPA code criteria for Halon concentration. Specifically, a minimum concentration of 5% was not maintained in the upper levels of the Switchgear Room. Becauge of this, the Halon system in the switchgear room had been declared inoperable (6; and a fire watch had been instituted in this area as required by the Technical Speci!! cation. In order to restore the Switchgear Room Halon System to operable status, CYAPCO committed to make the following modifications:

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a. Install new supervised electric circuits and release mechanisms,

b. Modify the Halon system to achieve a 5% (minimum) concentration of Halon for at least a 10 minute duration. These modifications may include installation of additional piping and/or Halon storage cylinders and modifications of the smoke detection system, as necessary, to satisfy the applicable NFPA codes.

These modifications were scheduled to be completed by January 1,1987 with a full i

discharge test scheduled to be conducted during the first refueling outage commencing af ter January 1,1987 or the first outage of greater than one week (7 days) duration commencing af ter January 1,1987.

In June,1986, CYAPCO performed a preliminary review of the Switchgear Room Halon System to determine what modifications would be required to upgrade the system to incet NFPA code provisions. This review indicated that modifications to the existing unsupervised pneumatic actuation piping and actuators as well as changes to the location and number of storage cylinders and smoke detectors would enhance the overall performance of the system. Although these modifications were significant, it was initia!!y judged that they could safely be accomplished with the plant operating prior to January 1,1987 and therefore the commitment to complete these modifications by January,1987 was made. Subsequently, as the detailed review of the current Switchgear Room llalon System progressed and a detalled design change package was developed, the scope of work required to complete the system upgrade increased extensively, protnpting concern that attempting to accomplish the modifications during plant operation could have a signi!! cant impact on the systems and components in the switchgear room with potential adverse safety implications. Because of the potential safety imp!! cations associated with attempting to perform the required modifications with the plant on line, and in recognition of the fact that plant operation af ter January 1,1987 with the current configuration is acceptable from a safety standpoint, CYAPCO is requesting NRC approval to defer implementation of the modifications to the 1987 refueling nutage or the first outage of at least eight weeks duration commencing af ter January I,1987.

I (6) It is noted that inoperability was declared solely because of the minimum concentration problem. The system remains armed and operable in every other respect.

SCOPE OF WORK Modifications to the Switchgear Roorn Halon System will be performed to achieve a calculated Halon concentration of seven percent (7%). Seven percent (7%)

represents the concentration upon which design calculations utilizing room volume and anticipated leakage are based, but does not represent the minimum Halon concentration level acceptab!c during the Halon discharge acceptance test. In accordance with NFPA 12A, the minimum acceptable Halon concentration is five percent (5%).

In order to enhance the overall system performance and achieve at least a 5%

Halon concentration throughout the Switchgear Room, modifications will be performed to the existing Halon 1301 Fire Suppression System. The required rnodifications have been engineered, designed, procured and will be installed under the auspices of Northeast Utilities Fire Protection QA Program.

Halon 1301 is an effective fire suppressant when utilized in concentrations of 5%

and greater in a given enclosure. In order to achieve this 5% minimum concentration in the Switchgear Room for a minimum of ten minutes, approxi-mately 3200 pounds of Halon will be delivered into the room. This volume of Halon represents a 7% (calculated) concentration and a!!ows for 296 leakage from the Switchgear Room. To provide for better Halon distribution and mixing, the existing distribution piping which directs the release of Halon 1301 upon receipt of an alarm signal from either the detection system or manual pull stations, will be rerouted as required to raise existing discharge nozzles to an elevation closer to the ceiling. Also, additional nozzles will be installed to enhance overall coverage.

To achieve the proper Halon concentration, additional Halon 1301 storage cylinders must be installed. Approximately two 600 pound capacity storage cylinders will be added and one 340 pound capacity storage cylinder will be deleted. In addition, at least one 340-pound capacity storage cylinder will be relocated.

Madifications to the detection system will include relocation of at Icast one exist-ing detector and the installation of approximately three additional detectors.

Graphics display and Halon control panel internal modifications will be required to support the addition of the new detectors.

The existing abort switch will be relocated to an area near the northwest entrance inside the Switchgear Room. The manual release portion of the existing abort switch assembly will rernain at its current location. Also, one additional abort switch will be Installed near the west entrance of the Switchgear Room.

The majority of the existing unsupervised pneumatic actuation piping and pneumat-Ic actuators associated with the Halon storage tanks will be reinoved and replaced with c!cctrically supervised solenoid actuators. All conduit and MC cabic will be supported in a manner which will preclude the possibility of their failure adversely impacting redundant safe shutdown equipment in the Switchgear Room during a scismic event.

To prevent a lon of flalon during the ten-minute soak period following the initial discharge, the existing battery Ian exhaust duct located on the Health Physics Building roof will be modified. The exhaust duct will be raised approximately seven feet to bring the c!cvation of the exhalst duct above that of the Switchgear Roorn roof. The exhaust fan currently shuts down on system actuation.

. _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ ____ _ _____ ~

In summary, the scope of work required for achieving code compliance and enhancing system performance will be accomplished by modifying the existing  !

Halon system as follows:

o Reroute existing and install additional distribution piping as necessary to raise the elevation of discharge nozzles. Also, additional nozzles will be installed to better distribute and maintain a uniform Halon concentration throughout the Switchgear room.

o Remove and replace the majority of the existing unsupervised pneumat-ic actuation piping and actuators associated with the Halon storage tanks with electrically supervised solenoid actuators to increase the reliability of the Halon system.

o Install approximately three additional and relocate at leaa one existing detector to increase the reliability of the Halon actuation scheme.

o Relocate the existing abort switch to an area near the northwest entrance and provide an additional abort switch near the west entrance of the Switchgear Room.

o Install approximately two additional 600-pound Halon storage cylinders, eliminate one existing 340-pound Halon storage cylinder, and relocate the existing 340-pound Halon storage cylinders as required. This will increase the calculated Halon concentration to 7% to provide a 2% cushion from the minimum acceptable Halon concentration of SE o Install additional duct to raise the battery fan exhaust duct to an elevation above that of the Switchgear Room ceiling, eliminating a leakage path for Halon during the ten-minute soak l 'eriod.

SAFETY IMPLICATIONS CYAPCO has performed an in-depth review of the construction plans and protec-tive requirements of perforrning the necessary Switchgear Room Halon System modifications while the plant remains in operation. The construction plan requires staging the area to protect equipment and includes precautions to minimize area man-loading and dust and debris. There is, however, a safety concern during the crection and removal of the staging.

The specific concerns can be broken down into three areas:

a) Inadvertent breaker operation or damage to protective relays.

b) Dust and/or debris migration into operating equipment / protective relays.

c) Probability of adverse effects based upon manhours required to install and remove the staging.

Staging is planned to be installed over sensitive safety-related equipment in the Switchgear Room, specifically MCC-5. At the lladdam Neck Plant, MCC-5 does not meet single failure criterion and has been granted a special exemption based upon the plant-specific desid n at fladdam Neck. Consequently, MCC-5 is the only

safety-related MCC which will automatically receive power upon a loss of normal power. An auto bus transfer feature loads MCC-5 on to either emergency diesel generator in the event of failure of one diesel generator. Semi-vital AC, both emergency diesel generator auxiliary panels, and service water MOVs rely on MCC-5 as a source of power. Although the probability of physical damage to MCC-5 is low, it is not inconceivable that circuit breakers could be inadvertently opened while manipulating staging during assembly and disassembly of the staging.

The most critical would be the feeder breaker to MCC-5 and the semi-vital power regulating transformers. Either case would most probably result in a plant trip, and would unnecessarily challenge the safety systems and the operating staff.

CYAPCO has investigated all possible precautions necessary to minimize dust generation and also to ensure adequate ventilation and cooling remains available to equipment within the switchgear room. A problem still exists with potential inadvertent dislodging of flammastic which covers many of the cables in the overhead of the switchgear room. This dust and debris could easily enter into the cooling / ventilation system of the relay and Control Rod Drive control cabinets and potentially lodge in a relay contact or armature. This could result in an undetectable failure of a relay or contractor. Such a failure did occur durmg the last refueling outage in the control room and therefore has been confirmed to represent a credible failure mode.

The remaining major area of concern is the manpower and amount of time which would be required to assemble and disassemble the staging necessary to protect equipment and to provid2 support for construction activities. Simply put, the likelihood of a problem occurring increases with a larger work scope. This staging must have the ability to protect the equipment in the Switchgear room and still

provide accessibility to the overhead work areas while ensuring operator access to this equipment. With the plant at power, more time would be required to assemble this staging to ensure that reasonable precautions are taken to prevent damage to operating equipment. The staging would be required to protect the MCCs, transformers, load centers, MG sets and rod control equipment directly under work areas and to provide a ceiling over the equipment above the discharge of the ventilation system to maintain adequate ventilation and cooling of the equipment.

This arrangement also would need to ensure protection from falling tools or materials and to ensure required corridors and access areas remain accessible to operations personnel to a!!ow for equipment operation. Exposed cabic trays and equipment cages, such as the battery cages, would need to be covered to prevent damage from overhead. The probability of inadvertent equipment operation and damage would be greatly reduced, and the consequences of such inadvertent operation or damage would be substantially minimized, if the modifications were to be perfortned with the plant shutdown.

In addition, although the existing lialon system has been declared inoperable per the Technical Specifications, it does provide some protection from a potential fire.

During the required modifications, the existing l{alon system would be disabled.

Combustibles will be brought into the Switchgear Roorn during construction of the modification. These combustibles will include lumber (fire retardent) for scaffold-ing, small amounts of solvents for pipe preparation, rags, boxes, etc. Although all welding and cutting required to support the modifications is planned to be performed outside the Switchgear Room, there is a potential that some welding or cutting may be required in the Switchgear Room resulting in the introduction of ignition sources to the room. All cornbustibles and Ignition sources will be strictly controlled; however, with the existing flalon system out of service and the plant in

operation, this would also pose an undesirable condition with potential adverse safety implications.

CONCLUSION As stated in CYAPCO's July 3,1986 and August 19, 1986 letters, CYAPCO had committed to complete the modifications to the Switchgear Room Halon System by January 1,1987 and to conduct a full discharge test during the first refueling outage commencing after January 1,1987 or the first outage of greater than one week duration commencing af ter January 1,1987. CYAPCO is requesting NRC approval to allow deferring completion of the required Switchgear Room Halon System modifications to the first refueling outage commencing after January 1, 1987 or the first planned or unplanned outage of at least eight weeks duration commencing af ter January 1,1987 based on the following:

o The actual scope of work required to complete the Switchgear Room Halon System upgrade to meet NFPA code requirements and to enhance the overall system performance has increased in complexity from what was originally thought to be required when the commitments were made.

o Attempting to perform the required modifications during plant opera-tion could have a significant impact on the systems and components in the Switchgear Room with potential adverse safety implications. This includes the potential for inadvertent breaker operation or damage and/or potential damage to protective relays, dust and/or debris migra-tion into operating equipment and protective relays, the increase in the probability of problems based upon the area man-loading required to install and remove the required protective staging, and the potential decrease in fire protection for safety related components due to the existing Halon system becoming disabled and the introduction of combustibles to the area, and the potential for introduction of ignition sources to the area.

o The modified Switchgear Room Halon System would not be declared operable until a successful full discharge test was performed. Per the current cominitments and schedule, this test would not be performed until the first refueling outage commencing af ter January 1,1987 or the first outage of greater than one week duration commencing af ter January 1,1987. Therefore, it is possible that the modified Switchgear Room Halon System would not be placed in service until the same time frame as it would be if the modifications were delayed as requested.

Hence, there is no significant loss of fire protection capability.

o With the deferral of the system upgrade, the currently installed Halon system would not have to be disabled and would continue to provide limited protection against fires in the area that would not otherwise be available during the modifications while the plant is operating.

o The current fire watches (one full time continuous watch and one roving watch) established because the existing Halon system has been declared inoperable would remain until the system upgrade is completed and satisfactorily tested ensuring that an adequate level of fire protection remains in effect.

o The full discharge test of the modified Switchgear Room Halon System would be performed immediately af ter the modifications were com-pleted, thus ensuring that the system will perform its intended function prior to the plant resuming operation.

o The expanded scope of the project is being reviewed, the work package is under development, and the required construction procedures and materials will be readily available to support completing the modifica-tions prior to start-up from the first qualifying outage.

o All other modifications to the plant required to be complete by January 1,1987 are on schedule. CYAPCO remains committed to this schedule for completion of these modifications.

CYAPCO has concluded that, based on the above justification, that the required modifications to the Switchgear Room Halon System can be delayed without reducing the current level of fire protection in the Switchgear Room, that attempting to perform the modifications per the current schedule with the plant in operation would create an unnecessary significant impact on the systems and components in the Switchgear Room with potential adverse safety implications, and that the actualinservice date of the upgraded Switchgear Room Halon System, if the full discharge test is not performed until the 1987 refueling outage , would be the same as in the original commitment.

Therefore, CYAPCO requests NRC approval and concurrence to defer implementa-tion of the modifications required to upgrade the Switchgear Room Halon System at the Haddam Neck Plant to the first refueling outage commencing after January 1,1987 or the first planned or unplanned outage of at least eight weeks duration commencing af ter January 1,1987.

We wish to emphasize that we are making this request for relief reluctantly, as we had every intention of meeting the January 1,1987 commitment date. This decision is a close call, as a considerable number of intangibles had to be carefully evaluated by CYAPCO. The fact that the systems and components of concern are not single failure proof is an important consideration, as this scope of work may have been acceptable if all the systems and components involved were redundant.

Having determined that the modifications to the Halon system are not prudent to undertake on line, and the continued plant operation with the existing configuration and controls is acceptable from a safety standpoint, the appropriate step to take is to seek the relief requested herein.

CYAPCO respectfully requests a written response to this request prior to Jan-uary 1,1987 and remains available to assist you in your review.

Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY h . F. (LL J. F.'Op6ka U Senior Vice President