ML20058N655

Summarizes Enhancements & Addl Nitrogen Inerting Sys Upgrades Completed During 14R Outage

ML20058N655
Person / Time
Site:	Oyster Creek
Issue date:	10/14/1993
From:	J. J. Barton GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
C321-93-2263, NUDOCS 9310200119
Download: ML20058N655 (4)

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GPU Nuclear Corporation t

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October 14, 1993

.U...S.-Regulatory Commission C321-93-2263 Attn: Document Control Desk Washington,-DC 20555.

t TGentlemen:

Subject:

Oyster Creek Nuclear Generating Station (OCNGS)

Docket No. 50-219 Facility Operating License No'. DPR-16 Nitrogen Inerting System E

References:

(3) GPUN letter C321-92-2184, dated 8/17/92 (2) NRC letter (TAC No. N62980), dated 11/18/92 (3)'GPUN letter C321-91-2179, dated 6/24/91

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L.By reference 2,

the NRC ' staff requested. confirmation that the proposed enhancements for the Nitrogen Inerting System (NIS) were implemented. A summary 1of the these enhancements and additional MIS system upgrades which were completed b

during the 14R outage is provided below.

A : bypass switch in' the control room ' permits operation of the purge and vent containment isolation valves when a containment isolation signal'is present. Air accumulators provide for. six (6):open and close cycles of the nitrogen p;rge

isolation valves in ' the event. the normal air system becomes inoperabic.

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. hardened vent permits venting of the containment via a hard pipe flow path. The LJCP&L combustion turbines on the Forked River site provide the Alternate AC power R

~ to Oyster Creek via, an underground ductbank/ trench system.. a new.10NVA,

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-13.8/4.16ky. 3 phase transformer and a new 4.16ky breaker / cubicle. The AAC. power f

source can be available within one hour of the' onset'of a station blackout event

1. " -and' has-sufficient capability and capacity to operate systems necessary to achieve and maintain safe shutdown.

The. additional NIS modifications include: '(1) upgrade of the pressure control 6

' valves; (2) the replacement of the electric vaporizer and the ambient vaporizer

with a; fan powered ambient vaporizer:(125,000 scfh), and.(3) the addition of an electrictrimheater-(110,000 scfh) with a redundant spare to heat the inerting

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gas.during cold weather conditions.

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. GPU Nuclear Corporati is a subsidiary of General Public Util: ties Corporat4on H

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LWe are'also submitting!our clarifications to the staff safety evaluation as an

attachment. The. completion'of these enhancements with our clarifications complete A, '

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our commitmentsion the 10 CFR 50.44 Combustible Gas Control' issue. -If you have

.any questions, please' contact Mr. Michael Laggart, Manager, Corporate Nuclear -

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Licensing at;(201)'316-7976.

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Very truly yours, f 7tsy p

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J. J. Barton=

,. c Vic e Yesident and Director h,ttrCreek N.1 Attachment

JJB'/DGJ:

fcc: Administrator, Region I Senior Resident' Inspector-0yster Creek NRC' Project Manager l

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Attachment Oyster Creek Huclear Generating Station Nitrogen Inerting System (NIS)

Combustible Gas Control System p

F Safety Evaluation (Sec. 3.1, p.5)

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Twice per shift the NIS will be walked down by an equipment operator.

This routine incpection will also include noting nitrogen tank level and pressure....

the NIS will be added to the plant walkdown which is done by a Senior Reactor Operator. The nonroutine inspections include a periodic system walkdown by a system engineer, and a quarterly inspection of the nitrogen pad equipment by the licensee's offsite nitrogen supplier.

GPUN clarification

- Every shift, an Equipment Operator tours the NIS tank and vaporizer area. This is completed as part of the intake area tour. This tour is required once during the eight hour shift, but the tour is normally done twice. During the required tour, tank pressure and level are recorded and verified to be within the specified limits. The second tour verifies that the limits are still maintained and compares information collected earlier with present conditions to note any changing trends. Tank pressure and level are not recorded on the second round.

Every shift, the SRO licensed Group Operating Supervisor (GOS) reviews the intake area tour sheet.

In this review, he ensures that nitrogen tank pressure and level are within the normal limits.

The Group Shift Supervisor (GSS) and GOS also periodically tour the plant. This tour is not all encompassing but does periodically include the NIS tank and vaporizer area.

The plant procedures used for purging the containment include steps to ensure proper equipment configuration and safe system operation.

The only nonroutine (no formal documentation) inspections will be performed by the system engineer.

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,e Safety _ Evaluation (Sec. 4.0, p. 7)

When the normal nitrogen tank reaches the low level stated in section 4 of Operating Procedure 312, an alternate source of nitrogen will be needed. The licensee has committed to an agreement with a nitrogen supplier that will provide

. a skid mounted portable system to the site.....The alternate supply will be connected via the fill connection located near the hardened vent valve station.

GPUN clarification During the 14R outage, an alternate nitrogen fill connection was provided near the hardened vent valve station. The vendor, who currently supplies nitrogen can also deliver a 6000 gallon portable nitrogen tank with a 20,000 scf/ hour ambient vaporizer..The alternate source of nitrogen is our proposed remedial action for a failure of the plant nitrogen system which cannot be repaired post LOCA.

In our initial survey (Ref.1) of nitrogen suppliers, this same vendor indicated a capability of providing emergency nitrogen within eight (8) to ten (10) hours.

After further discussions, the nitrogen vendor stated eight to ten hours as their capability to deliver the product (nitrogen) only and it was not their intent to make a contractue1 commitment to deliver a wholly separate nitrogen tank and vaporizer within the same time frame.

In their recent quote, the vendor l

committed to a delivery time within five days or less after notification.

Assuming a complete failure of the NIS and a maximum of five days for delivery of the alternate source of nitrogen, there is still sufficient time to maintain an inert containment based on our calculated oxygen generation rate (Ref. 3).

Further, the delivery time reflects a commercial decision by the vendor and does not reflect their actual capability to respond in an emergency. Based on these facts, we conclude that the delivery time is reasonable and we will proceed to finalize the contract.

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