ML20216H709

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Safety Evaluation Supporting Amends 229 & 232 to Licenses DPR-44 & DPR-56,respectively
ML20216H709
Person / Time
Site: Peach Bottom  Constellation icon.png
Issue date: 09/24/1999
From:
NRC (Affiliation Not Assigned)
To:
Shared Package
ML20216H681 List:
References
NUDOCS 9910010447
Download: ML20216H709 (4)


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NUCLEAR REGULATORY COMMISSION

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 229 AND 232 TO FACILITY OPERATING LICENSE NOS. DPR-44 and DPR-56 4

PECO ENERGY COMPANY PUBLIC SERVICE ELECTRIC AND GAS COMPANY l

i DELMARVA POWER AND LIGHT COMPANY ATLANTIC CITY ELECTRIC COMPANY l

PEACH BOTTOM ATOMIC POWER STATION. UNIT NOS. 2 AND 3 I

DOCKET NOS. 50-277 AND 50-278 I

1.0 INTRODUCTION

By letter dated March 29,1999, as supplemented July 21,1999, the PECO Energy Company (the Licensee) submitted a request for changes to the Peach Bottom Atomic Power Station,

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I (PBAPS) Unit Nos. 2 and 3, Technical Specifications (TSs). The requested changes would

. delete the requirement associated only with the refueling platform fuel grapple fully retracted position interlock input, which currently is required by TS Surveillance Requirement - (SR) 3.9.1.1. The proposed change will remove the fuel grapple fully retracted position (not fully up) interlock input, and the plant will also be modified to remove this position from the plant design.

The objective of the refueling interlocks in combination with the refueling procedures is to prevent an inadvertent criticality during refueiing operations. The refueling operations include the removal of reactor vessel upper internals and the movement of spent and fresh fuel assemblies between the reactor core and the fuel storage pool. The refueling platform and the

. equipment-handling hoists on the platform are used to accomplish the refueling task.

The July 21,1999, letter provided clarifying information that did not change the initial proposed no significant hazards consideration determination.

. 2.0 EVALUATION Ths FBAPS refueling interlocks are active when the reactor mode switch is in the shutdown or the refueling position. These interlocks, in combination with the refueling procedures, ensure safe movement of fuel.

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r 2-The current refueling equipment interlocks are required in TS 3.9.1, and inputs are identified in SR 3.9.1.1, which include the following:

e All-rod-in, Refuel platform position, Refuel platform fuel grapple, fue! loaded, e

i Refuel platform fuel grapple fully retracted position, e

Refuel platform frame mounted auxiliary hoist, fuel loaded, and e

i Refuel platform monorail mounted hoist, fuel loaded.

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These interlock conditions are combined in the logic circui! of the reactor manual control system j

(RMCS) to determine if all restrictions on refueling equipment operations and control rod

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insertion are satisfied. This circuitry senses the con'.iiiions of the refueling equipment and the control rods, and depending on the sensed conditio is, interlocks are actuated to prevent the operation of the refueling equipment or the concurrant withdrawal of control rods.

As discussed in the PBAPS Units 2 and 3 Updated Final Safety Analysis Report, Section 14.6.4, Refueling Accident, the refueling interlocks are not used to prevent or to mitigate the fuel-handling accident. These interlocks are not assumed as an initial condition in the control rod drop accident, which is the most limiting condition during the normal power operating condition. They are designed to reinforce administrative procedures for moving fuel during refueling outages. These interlocks monitor the main, auxiliary, and monorail hoists conditions on the refueling 1.: ridge, and prevent the refueling bridge from moving toward the core if there is a control r-J withdrawn, and any of the hoists are loaded with fuel or the main hoist fuel grapple is not in the fully up position. This action prevents a fuel bundle from being inserted into a core location with a control rod withdrawn. This action also prevents a potential i

inadvertent criticality of the reactor.

Additionally, a rod block signal will be sent to the RMCS if any of the hoists are fuel loaded or the bridge is over the core. This action prevents a control rod from being withdrawn while fuel is being inserted into the vessel.

The licensee states that when the control rod drives (CRDs) are being replaced during an outage, the main hoist, which includes the fuel grapple, is used to perform CRD blade guide movements in the vessel. The CRD mechanism located under the vessel cannot be removed because of the rod block signal associated with the fuel grapple fully retracted position.

Therefore, CRD removal activities must be stopped whenever the main hoist is being used to perform the CRD blade guide movements. This interruption in the refueling operation unnecessarily increases personnel exposure and affects outage critical path activity. The licensee states that preventing work activities associated with CRD removal was not the intent of this rod block, in its submittal, PECO Energy states that the refueling platform fuel grapple fully retracted interlock is redundant and diverse to the fuel grapple fuel-loaded interlock. The main hoist uses a telescoping boom, which consists of several sections that are supported by cable and monitored by a load sensor. As each section of the boom is fully extended, its weight is no longer supported by the cable, but by tM section above it.

., l The weight sensed by the load sensor is the total weight of the fuel bundle, plus any sections of the boom that have not fully extended. A combined weight of the fuel bundle and the bottom section of the boom is more than 600 lbs, and the current fuel grapple fuel 'oaded setpoint is set at 550 lbs. This setpoint, in combination with the refueling procedures, ensures that a rod block signal would be provided to prevent a control rod from being inadvertently withdrawn

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concurrently with fuel movement. In the event that a rod block signalis not positively verified by the operators, the refueling procedure would prohibit continued operation of fuel movement.

Therefore, the refuel grapple fully retracted position is not needed. The fuel grapple limit switch-associated with this position will continue to stop its upward motion, and will also continue to provide the full up position indication. However, its fully retracted position interlock signal will be removed from the RMCS, and a 7-day SR will no longer be required.

The staff has reviewed the information that the licensee has provided and considers that the

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fuel grapple fuel-load interlock in conjunction with the existing administrative controls are sufficient to prevent control rods from being inadvertently withdrawn during fuel movement and will provide adequate protection from inadvertent reactivity addition accidents. The removal of the fue! grapple fully retracted position will not affect the fuel-rnoving operation and will enhance j

the CRD removal and maintenance processes. In addition, the refueling administrative procedur6s will continue to prohibit concurrent withdrawal of control rods e-d fuel movement in the vessel. Therefore, the proposed deletion of the fuel grapple fully retracted interlock and its associated SR is acceptable.

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3.0 STATE CONSULTATION

in accordance with the Commission's regulations, the Pennsylvania State official was notified of the proposed issuance of the amendments. The State official had no comments.

4.0 ENVIRONMENTAL CONSIDERATION

The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change j

surveillance requirements. The NRC staff has determined that the amendments involve no i

significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (64 FR 43774). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.

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4 5.0, CONCLUSION The Commission has concluded, based on the considerations discussed above, that (1) there

. is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor: D. Diec

. Date: September 24,1999