ML20055F851

Application for Amend to License DPR-16,consisting of Tech Spec Change Request 188,reducing Low Condenser Vacuum Scram Setpoint in Table 3.1.1 to 20 Inches Hg & Revising Bases to Support New Setpoint

ML20055F851
Person / Time
Site:	Oyster Creek
Issue date:	07/10/1990
From:	Fitzpatrick E GENERAL PUBLIC UTILITIES CORP.
To:
Shared Package
ML20055F850	List: ML20055F849 ML20055F851 ML20055F852
References
NUDOCS 9007190292
Download: ML20055F851 (5)

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GPU NUCLEAR CORPORATION OYSTER CREEK NUCLEAR GENENATING &YATION s

PROVISIONAL OPERATING l

LICENSE NO. DPR.

Technical specification Change Request No.'188 Docket No. 50-219 Applicant submits, by this Technical specification Change. Request No. 188, i

to the Oyster Creek Nuclear Generating Station Technical specifications, a change to pages 3.1-4, 3.1-5 and 3.1-8.

By:

E. E. Fitzpadrick

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Vice President and Director Oyster Creek Sworn and subscribed to before me this day o

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1990.

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NOTARY PUBLIC NEW-JERSEY l

DIANA M. DeBLASIO -

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l UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION IN THE MASTER OF

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DOCKET No. 50-219 GPU NUCLEAR CORPORATION )

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A CERTIFICATE OF SERVICE i

i This is to certify that a copy of Technical Specification Change. Request No. 188 l

for the Oyster Creek Nuclear Generating Station Technical Specifications, filedL with the United States Nuclear Regulatory Commission on. ' July.10 1990, has this i

day of July 10 1990, been served on the Mayor of I:acey Township, Ocean County, New Jersey by deposit in the United States mail, addressed as follows:

The Honorable Debra Madensky Mayor of Lacey Township 818 West Lacey Road Forked River, NJ 08731 By:

E. E.'Fitzpatrick l

Vice President and Director Oyster Creek r

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1 OYSTER CREEK NUCLEAR CENERATING STATION PROVISIONAL OPERATING LICENSE NO. DPR-16 DOCKET NO. 50-219 TECHNICAL SPECIFICATION CHANGE REQUEST NO. 188 Applicant hereby requests the Commission to change Appendix A to the above captioned license as indicated below.

Pursuant to 10CFR$0.91, an analysis concerning the determination of no significant haaards considerations is alsi presented:

1.0 Section to be Chanced Sees!on 3.1 entitled " Protective Instrumentation".

I 2.0 Extent of Chanos This change request proposes to reduce the low condenser vacuum scram setpoint in Table 3.1.1 from 23 inches Hg to 20 inches Hg and revises the bases to support the new setpoint.

3.0 chanaes Reauggj;pj The requested change is shown on the attacned Technical Specification pages 3.1-4, 3.1-5 and 3.1-8.

4.0 Discussion The OCNGS Technical Specifications currently require a reactor scram on low condenser vacuum with a trip setting equal to or greater than 23 inches Hg.

Restrictive requirements are placed upon the actual setpoint to ensure that the Tech Spec is not exceeded. During the summer months l

when condenser cooling water is at its highest temperature, the margin between the operational vacuum and the scram setpoint is minimal. As a normal procedure, the condenser must be backwashed which further reduces j

the margin. Under these conditions, it becomes difficult to maintain full power operation while backwashing a condenser section. The possibility of a spurious reactor scram is increased greatly during this period.

Reducing the scram setpoint to 20 inches Hg will'better accommodate backwashing operations. As discussed below, GPUN has determined that this change has no effect on reactor safety, e.g.,

the low vacuum scram has no safety function. The scram function is being retained in the Tech specs because it does provide a reliable backup scram for turbine and condenser protection and this benefit is preserved with a setpoint of 20 inches Hg.

The Tech Spec bases on page 3.1-4 state the low condenser vacuum scram trip of 23 inches Hg has been provided to protect the main condenser in the event that vacuum is lost. A decrease in condenser vacuum (22 inches Hg) will cause the turbine stop valves to close resulting in a turbine l

trip. The closure of the stop valves will cause a reactor scram signal l

independent of the low vacuum scram. Currently the low vacuum scram anticipates this transient and trips the reactor protection system at 23 inches Hg.

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,1 An cn31ysio cf the condenser rO:ponto to leco of v2 suum cv:nto w 0

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performed using a computer model (RELAPS Mo02).- The model was used to

' evaluate several degraded Sondenser cooling and increased air inleakage events. The evaluation of these events showed that a setpoint of 20 inches Hg had little or no impact upon condenser protection as compared I

with 23 inches Hg.

In the analysis of the loss of condenser vacuum event'in Chapter 15 of the FSAR, no credit is taken for the reactor scram trip on low condenser vacuum. This event is bounded by the turbine trip without bypass transient.

Further, no cradit is taken for this trip in any other l

transient analysed in the FSAR.

An analysis was also performed to evaluate the impact of the low vacuum 1

scram upon the reactor pressure vessel (RPV) using a computer model j

(RETRAN).

The results showed that the RPV response was acceptable l

regardless of the setpoint and does not impact the licensing reload analysis. With a scram setpoint below the turbine trip for a rapid loss of condenser vacuum (2 inches Hg/sec), the event is bounded by a normal j

turbine trip.

For an instantaneous loss of vacuum, the event is bounded by a turbine trip without bypass. operating limits of the plant are conservatively astablished by the turbine trip without bypass.

Therefore, the low vacuum scram satpoint does not impact those limits.

From a turbine protection point of view, the low vacuum scram should be set in the proximity of the low vacuum-turbine trip.

This will insure that, if there is no turbine trip _on low vacuum, the turbine will not

-operate under excessively low vacuum conditions for an extended period of time.

A scram setpoint of 20 inches Hg provides sufficient margin between the scram and the condef.aa.r bypass valve closure (7 inches Hg). This margin-is critical to avoid a potential condenser isolation prior to the scram.

At 23 inches Hg, the scram occurred prior to the turbine trip (22 inches Hg). With a 20 inch Hg setpoint, the scram will occur after the turbine trip.

Since the turbine trip also produces a scram, the low vacuum scram would provide a scram backup.

In the event that the turbine trip on low vacuum does not occur, the low vacuum scram will initiats the load l

reduction required to protect the condenser.

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i 5.0 Determination GPUN has determinod that this Technical Specificattan Change Request involves no significant hasards consideration as defined in 10CFR50.92.

5.1 operation of the f acility in accordance with the proposed amendment would not involve a significant increase in the probability of occurrence or the consequences of an accident previously evaluated. No credit is taken for the. low cendenser vacuum scram in any of the transients analyzed in the FSAR. The turbine trip without bypass transient bounds the loss of condensor vacuum 1

scenario.

5.2 operation of the facility in accordance with the proposed amendment would not creats the possibilit.y of a new or different kind of L

accident from any accident previouoly evaluated. The scram L

function on low vacuum is still being preserved, and an evaluation p

has demonstrated that the lower setpoint provides an acceptable l

response to loco of vacuum scenarios.

i 0-5.3 Operation of the facility in accordance with the proposed amendment would not involve a significant reduction in a margin of safety.

operating limits for the plant are conservatively established with the more bounding turbine trip without bypass transient.

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6.0 Implement 4 tion j

It is requested that the amendment authorising this change become effective upon issuance.

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