ML17213B090

Forwards Justification for Not Installing Source Range Nuclear Instrumentation Isolation Device & Containment Flame Impingement Shields in Fire Protection Sys Prior to Core Load

ML17213B090
Person / Time
Site:	Saint Lucie
Issue date:	02/25/1983
From:	Robert E. Uhrig FLORIDA POWER & LIGHT CO.
To:	Eisenhut D Office of Nuclear Reactor Regulation
References
L-83-99, NUDOCS 8303040458
Download: ML17213B090 (8)

Text

'REGULATORY ORMATION DISTRIBUTION SY M (RIDS)

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YES FACIL:50<<389 'St ~. Lucie Pl anti Uniit 2~

Fl or ida;Power 8'ight Co.

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RBC IP. NAME REC IP IENT, AF F IL'-I ATION EI'SENHUTr Di'G ~

Di.vision of Licensing DOCKET 05000389

SUBJECT:

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OX 14000, JUNO BEACH, FL 33408 Q I/r FLORIDAPOWER St LIGHTCOMPANY February 25 1983 L-83-99 Office of Nuclear Reactor Regulations Attention: Mr. Darrell G. Eisenhut, Director Division of Licensing U.S. Nuclear Regulatory Commission 4'ashington, D.C.

20555

Dear Mrs Eisenhut:

Re:

St. Lucie Unit No.

2 Docket No. 50-389 Fire Protection S stem FP&L letter L-83-65 dated February 9,

l'983 provided responses to NRC questions regarding the St. Lucie Unit 2 Fire Protection system and a schedule for completion of all work.

Subsequent discussions between the staff and FP&L regarding that submittal have resulted with the staff requesting additional detailed information regarding the justification for not installing the Source Range Nuclear Instrumentation Isolation device and the Containment Flame Impingement Shields prior to core load.

Attached is FP&L's justification for interim operation for these two areas.

Please contact us if you have any questions regarding this matter.

Very truly yours, Robert E. Uhrig Vice President Advanced Systems and Technology REU/RJS/PPC/mp Attachment cc:

J.P. O'Reilly, Region II Harold F. Reis, Esquire 8303040458 830225 PDR ADOCK 05000389

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ATTACHMENT The following two items will not be completed by core load.

Each justification below includes a description, the reason that it is not complete, the schedule for completion and the justification for operation until it is complete.

RCB Cable Trav Flame Imnin ement Shields D ~

b.

FP&L has committed to install horizontal flame impingement shields in the Reactor Containment Building on all redundant cable trays containing safe shutdown cables.

These shields will be installed below the lowest tray in each stack.

The reason that this modification will not be completed by core load is construction/design oriented.

Separating the redundant cable trays in the RCB will affect approximately two hundred cable tray supports.

The work involved in completing this task includes; (1) compilation of as-built data on two hundred affected cable tray supports; (2) re" analysis of fifty typical tray supports (determined from (1) above) to ensure that the seismic qualification of the trays is maintained (3) de-tailed design of the flame shield support frame; (0) development of re-inforcing details on an estimated 30 typical cable tray support designs needing modification,and(5) upgrade of drawings, issue of sketches and plant change modifications.

In addition to the effort described

above, the following construction schedule constraints exist; (1) the craft necessary to install these shields are being utilized to install other items that have been committed to becompleted prior to core load (i.e. tray riser fire stops, conduit plugging, conduit wrapping, conduit seismic supports and analyses);

(2) At this stage of the project schedular windows are not available to install these shields without severe impact on the upcoming major milestone (i.e. safeguards

testing, core load and initial criticality) and; (3) once the core is loaded, construction activities within the RCB are going to be restricted due to cleanliness and security requirements.

c.

The flame impingement shields in the RCB will be installed by the end of the first refueling.

d.

Operation of the reactor prior to installing the flame impingement shields is justified for the following reasons:

1. Administrative controls on site require a high degree of cleanliness in containment prior to plant operation.

This criter'a stems from requirements regarding sump clogging, seismic and missile analyses'owever, this cleanliness requirement will a)so ensure that the number of fire hazards are reduced.

Conta'nment surveys are performed before operation to insure all materials are removed which are not designed for in-containment.

This will necessitate the removal of any potential transient combustibles before reactor operation.

Because of this requirement, the probability of a transient combustible fire is minimal.

2.

Smoke detectors are located in the area where the flame impingement shields are to be installed.

The likelihood of an undetected fire is thereby reduced.

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3.

Hose stations are located in containment such that any location can be reached by a fire hose.

In conjunction with the trained fire

brigade, this reduces the possibility of a fire causing severe damage to any equipment and cables.

4.

The floor areas under the cable trays contain floor drains which go to a control sump.

If a liquid combustible were to be present, all but a small portion would be harmlessly drained to the sump.

This reduces the likelihood of there being a large transient combustible fire.'.

All cable trays are of the solid bottom design.

These solid bottom trays act as flame impingement shields for small or short duration fires.

This also reduces the likelihood of a fire damaging any cables.

6. All cables in the RCB are IEEE-383 qualified regarding flame retar-dation properties.

In conjunction with the solid bottom trays, this essentially removes the cable as a source of fuel for com-bustion in the containment.

This reduces the likelihood of a fire being propagated or sustained in the containment.

7.

The containment contains 2.5 million cubic feet of free volume.

This massive area basically categorizes the containment as an outdoor area with regard to a fire. It prevents hot gas stratification and reduces radiant heating effects 'thus greatly reducing the potential damage of a fire.

8.

The reactor coolant pumps have an oil collection system.

Mith the exception of the cables the reactor coolant pump oil system is the on'y other major source of in-situ combustibles in con-tainment.

The system is designed to remove the combustible as a fire hazard in containment.

In conclusion, FP&L believes that with the present eouipment configuration and installed fire protection devices, the probability of a fire in con-tainment capable of reducing the safety of the plant is sufficiently low as to warrant delaying the installation of the cable tray stack flame impingement shields until the end of the first refuel,ing, II. Source Ran e Nuclear Instrumentation a

~ Florida Power

& Light is committed to provide remote source range nuclear instrumentation existing at the Hot Shutdown Panel with isolation from the control room instrumentation.

b.

The reason why this modification to the existing system cannot be completed prior to core load is construction/design oriented.

In order to implement a design change which will provide redundancy between the control room and the Hot-Shutdown Panel

area, the design concept and details must be completed, implemented, parts ordered and installed.

At this time, FP&L has not yet completed the final design and has not fully procured all the necessary.

hardware for this modification to proceed.

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c. This modification will be completed by the end of first refueling.

d. Operation of the reactor prior to completion of this modification

's justified since the existing neutron source range instru-mentation will be operational within the control room and the Hot Shutdown Panel area before core load without the isolation capability.

The only means by which this capability could be eliminated would be by a significant fire.

Additionally, there are alternate means to insure reactor shutdown if all neutron instrumentation is incapacitated, namely boron sampling.

Finally, plant operators do not rely heavily on the information provided by the neutron source range monitor for securing plant shutdown, but use this information as an alternate status of plant condition.

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