ML20206H954

LAR 251 for License DPR-16,requesting Approval to Handle Loads Up to & Including 45 Tons in Reactor Bldg During Power Operations

ML20206H954
Person / Time
Site:	Oyster Creek
Issue date:	04/28/1999
From:	Roche M GENERAL PUBLIC UTILITIES CORP.
To:
Shared Package
ML20206H949	List: ML20206H944 ML20206H954
References
IEB-96-002, IEB-96-2, NUDOCS 9905120065
Download: ML20206H954 (7)

Text

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GPU NUCLEAR CORPORATION OYSTER CREEK NUCLEAR GENERATING STATION Facility Operating License No. DPR 16 License Amendment Request No. 251 Docket No. 50 219 1

Applicant submits, by this License Amendment Request No. 251 to the Oyster Creek Nuclear Generating Station Operating License, a request to handle loads up to and including 45 tons in the j reactor building during power operations.

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I h bW Michael B. Roche l Vice President and Director i Oyster Creek l 1

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Sworn and Subscribed to before me this M day of (1radA 1999-l Mf A Notary Public of NJ l 99051f.'0065 990428 '

PDR ADOCK 05000219 P PDR GERALDINE E. LEVIN HOTARTPtsuc0FIE!wAl8EY W Comsten Eghs k ' F - *> @

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Oyster Creek Generating Station Facility Operating License No. DPR-16 Docket No. 50-219 License Amendment Request 251 Applicant hereby requests that the Nuclear Regulatory Commission change the license cited above as indicated below. Pursuant to 10 CFR 50.92, an evaluation concerning the determination of no significant hazards is also presented.

Proposed Amendment I. Background / Purpose GPU Nuclear uses the Oyster Creek reactor building crane to move heavy loads on a regular basis to support various maintenance activities. The frequency of heavy load handling tends to increase during the ramp up period prior to refueling outages. NRC Bulletin 96-02 indicates the submittal of a license amendment request is required if the licensee plans to move " heavy loads over spent fuel, fuel in the reactor core, or safety-related equipment while the reactor is at power...and that involve a potential load drop accident that has not previously been evaluated in l the FSAR". This submittal is in response to that Bulletin. This request does not include loads containing spent fuel assemblies.

II. Description of Request GPU Nuclear requests NRC review and approval of GPU Nuclear's methodology and disposition of handling loads of up to and including 45 tons with the Oyster Creek reactor building crane while the reactor is at power. The 45 ton limit is a bounding case for all items weighing more than 800 pounds up to and including 90,000 pounds. The reactor building crane has a rated capacity of 100 tons and a safety factor of 5 with respect to ultimate strength. Therefore, for the loads considered under this amendment, a crane safety factor of at least 11.1 with respect to the ultimate strength will be available. l In addition to the high crane safety factor, all lifts performed under this amendment will be handled in accordance with Oyster Creek commitments to NUREG-0612 Phase I. Lifts performed under this amendment will employ redundant rigging with a design safety factor of at least 5 to 1 for each rig whenever practical. If redundant rigging is not practical, single rigging with a design safety factor of at least 10 to I will be employed. The redundant slings or lifing devices will be employed such that a single component failure or malfunction in the sling will not result in uncontrolled lowering of the load. The lifting devices will be employed in I accordance with existing NUREG-0612 commitments to ANSI N14.6 - 1978. Slings will be .

l chosen in accordance with existing commitments to ANSI B30.9 - 1971.

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License Amendment Request 251 1 Page 2

.III. Evaluation and Bases for Safety Findings i GPU Nuclear has implemented Phase I, NUREG-0612 " Control of Heavy Loads at Nuclear Power Plants". The NRC issued a Safety Evaluation Report (SER) on June 21,1983 which concluded that Oyster Creek's implementation of Phase I was acceptable.

NRC Generic Letter 85-11 dated June 28,1985," Completion of Phase 11 of Control of Heavy l Loads at Nuclear Power Plants", concluded that the Phase I guidelines of NUREG-0612 assure that the potential for a load drop is extremely small and that the NUREG-0612 objective for providing maximum practical defense in depth is satisfied by the Phase I compliance.

l GPU Nuclear has taken additional measures to reduce the potential for a load drop. These measures include instrumentation and control improvements to the reactor building crane, various redundant rigging schemes, personnel training (which includes mock ups for th arger loads), and the use of detailed lifting procedures to further minimize the potential for human j error. I Identification of Heavy Loads NUREG-0612 defines heavy loads as any load, carried in a given area after a plant becomes I operational, that weighs more than the combined weight of a single fuel assembly and its associated handling tool for the specific plant in question. That weight at Oyster Creek is 800 pounds. The 90,000 pound limit bounds the weight ofitems to be lifted while the reactor is at power. 4 Crane Reliability NUREG-0612 provides sumr,. aries of OSHA, Navy and NRC LER data which provides bounds 4

l on probability and derives an average load drop probability of 2.7 x 10 per lift from available l Navy data. However, as indicated in the NUREG, typical Navy operator training and procedures are not as detailed as those required to comply with NUREG-0612. Furthermore, Navy data l

includes operation of a large number of boom type cranes that are more susceptible to failure

than overhead cranes. Therefore, the probability of a load drop with the Oyster Creek reactor building crane will be lower.

l Specific Reactor Building Crane Design Features The crane has a main hoist rated capacity of 100 tons and a safety factor of 5 to 1. The loads addressed by this amendment request will be lifted with the crane main hook and will be less than or equal to 45 tons. Therefore, a crane safety factor of at least 11.1 with respect to ultimate l

i strength will be available for these loads. The rigging safety factors will be 10 to 1 or 5 to 1 with l redundant rigging.

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3 License Amendment Request 251 Page 3 Within this margin of safety, the most likely causes of failure are the following:

A. Failure of the hoist cable due to two-blocking.

B. Damage and eventual failure of cable due to wire rope mis-spooling.

C. Failure of braking features that could result in a load drop if the crane controls fail.

Enhancements to the control system fo: the reactor building crane were made with state-of-the-art hardware for controlling nearly all crane functions. Those enhancements are summarized below:

Dual power circuit upper limit switches are installed on the main and auxiliary hoist to directly interrupt power to the hoist motor. This reduces the possibility of two-blocking as a result of a failure of the existing control limit switches.

A remote control system was added which incorporates human factors considerations. This j feature will significantly improve load handling ability in the equipment hatch area as load l movement will be visible to the operator from the floor, which is not possible from the cab.  !

New controls were installed in the operator's cab that provide spring-return-to-normal function.

These controls consider human factors requirements in their design.

Various main hoist monitoring systems were installed. These include drum over-speed protection, mechanical drive train continuity detection and wire rope spooling monitor. Speed indication is available in the cab for all crane drives.

A load cell and weight displays were installed for the main hoist. The cell is located in the equalizer sheave pin. The weight displays were installed in the cab, on the 119' elevation and .

the 23' elevation to provide an indication of potential over-capacity lifts. A sudden increase in the display value would indicate to the operator or an observer that the load may be hung up.

Phase loss / phase reversal protection was installed. Phase loss results in substantial loss of drive motor torque and possible load drop. The detector device sets all brakes upon indication of phase loss / phase reversal.

The original crane drive system has been replaced. All four motors (bridge, trolley, main hoist and auxiliary hoist) are AC motors and are driven by variable frequency drives. These drives provide precise speed control and dynamic breaking capability. They also provide torque limitation that reduces the probability ofload snatch.

l License Amendment Request 251 Page 4 Following the above modifications, the reactor building crane was load tested to 125% of rated capacity. The modifications described above have further reduced the probability of a load drop while using the reactor building crane. The reactor building crane features to protect against two-blocking and wire rope misspooling incidents are equivalent to similar features for a single failure proof crane.

The main hoist has three independent braking features, as follows, a dynamic braking feature is provided by the hoist motor in conjunction with the motor drive. This is the primary (initial) means of braking a moving load when the crane is energized and the controls are functioning. I There are two newly installed independent brakes. One brake has a dynamic rating of 132% of the main hoist torque rating and is an integral part of the hoist motor. The other brake has a dynamic rating of 121% of main hoist torque rating and is located on the high speed shaft (input shaft) of the gear box and therefore would stop the load for a motor shaft or motor coupling failure. The brakes nomially act only as a holding brakes but will activate to stop a moving load l on loss of electrical power or control signal failure. l The braking systems available have sufficient independence and redundancy to preclude a load drop of a class ofloads which otherwise present no c.hallenge to the load carrying members of the crane.

Under normal conditions, the power to the crane is fed by one 480V circuit from vital motor control center (MCC) IB2 via a disconnect switch on the 119' elevation in the reactor building.

During a loss of off-site power, MCC IB2 is supplied by the number two emergency diesel generator. Upon the loss of AC power from the 480V feed, none of the crane motors will be operable until the power is restored. The loss of AC power will cause the brake coils to de-energize and the brakes to engage.

The limit switches on the associated drive (i.e., bridge, trolley or hoist), when activated, will l cause the drives to stop and their brakes to engage. The other methods to engage the brakes involve operator actions to de-energize the brake coils to cause the brakes to engage. The methods are:

• Master control switches for the crane e Power on/off buttons

. Main disconnect switch in the cab l . Disconnect switch on the 119' elevation

License Amendment Request 251 Page5 ,

Considering regulatory compliance, enhanced operator training, initial crane reliability and the improvements to the crane, GPU Nuclear believes that an adequate level of protection against j

load drop accidents has been provided.

Safe Load Paths Considering the number ofitems that are lifted, and the variety of purposes for lifting and moving them, no single safe load path could apply to all items. In accordance with GPU Nuclear's NUREG-0612 commitments, procedural guidance and administrative controls will prescribe safe load paths and limit the height at which a load is carried to the minimum possible to accomplish the task.

IV. No Significant flazards Consideration GPU Nuclear has reviewed the proposed license amendment relative to the no significant hazards consideration criteria in 10 CFR 50.92 and made the following determinations:

1. It will not involve a significant increase in the probability or consequences of an accident previously evaluated.

The probability of a load drop is dependent upon the reliability of the handling system and operator training. The reliability of the Oyster Creek reactor building crane was assessed during the NUREG-0612 review. The crane and associated handling provisions were determined to be adequate for the heavy loads considered at the time of that review.

Modifications have been made to the crane in order to improve its reliability. In addition, procedural controls and training have also been upgraded. These changes improve the reliability of the crane and its handling system. As a result, the probability of dropping a heavy load of the type considered in this amendment is not increased. In recent years the enhancements to the reliability and controls of the reactor building crane have further reduced the probability of a drop of this type from the threshold previously deemed acceptable. Thus, an adequate level of protection against dropping a load of the magnitude considered in this amendment has been provided while the consequences of such a drop have not changed.

2. It may create the possibility of a new or different kind of accident from any accident previously evaluated.

Heavy load handling provisions have been a part of plant design and included in the licensing basis. GPU Nuclear's response to NUREG-0612 considered load drops and concluded that various loads could be safely handled. A table ofloads is included in the f

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l FSAR. The NRC acknowledged Oyster Creek's successful implementation of Phase l' requirements of NUREG-0612 in an SER. NUREG-1382 reiterated this acceptance and stated that the objective of providing maximum possible defense in depth is satisfied.

However, although extremely unlikely, the potential drop of a load up to 45 tons in j magnitude in the equipment hatch, while traversing the 119' elevation of the Reactor l Building or in the cask drop protection system may create the possibility of a new or different accident than previously identified.

The design and reliability of the crane, personnel training and procedural controls, and l compliance with NUREG-0612 Phase I guidelines assure a high degree ofload handling reliability. Redundant rigging employing devices chosen in accordance with ANSI 14.6 or ANSI 30.9 will preclude the dropping or uncontrolled lowering of a load. Where  ;

redundant rigging is not feasible, the rigging will have a safety factor of 10. Redundant rigging combined with recent enhancements to the crane instrumentation and controls f '

have greatly reduced the probability of a drop such that GPU Nuclear believes an l adequate level of protection against load drop accidents has been provided.

3. It will not involve a significant reduction in a margin of safety.

The activity does not decrease any margin of safety. Oyster Creek Technical Specification 5.3.1.B prohibits handling heavy loads over spent fuel in the spent fuel i storage facility. The Oyster Creek SAR considers the drop of a 100 ton fuel emk in the l i cask drop protection system (CDPS). The only load, considered under this amendment, l l that will travel over the spent fuel pool involves a Radwaste Shipping Cask (RWSC). )

l The RWSC will follow an established safe load path to the CDPS and not travel over i spent fuel. Handling of the shield plug over a loaded fuel cask in the CDPS is addressed l separately by Amendment No.187 dated November 7,1996. Therefore, for the 1 l previously analyzed cask drop accident, safety margins are preserved. The reactor j building crane is rated for loads up to 100 tons. All loads addressed by this amendment I are 45 tons or less. Therefore, the margin of safety regarding crane capacity is not j reduced.

V. Implementation GPU Nuclear requests that the amendment authorizing this change be effective upon issuance.

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