ML20056E402

Provides Response to Addl Info Request Re TS Change Request 202.Concerns Re Heavy Loads & Thermal/ Hydraulic Parameters During Replacement of Spent Fuel Pool Storage Racks Discussed

ML20056E402
Person / Time
Site:	Beaver Valley
Issue date:	08/16/1993
From:	George Thomas DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TAC-M84673, NUDOCS 9308230313
Download: ML20056E402 (13)

Text

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Beaver Valley Power Station Shippingport. P A 15077-0004 (412) 393-5206

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(412) 643-8069 FAX f

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GEORGE S THOMAS Dnnsion Vice Prescent Nudear Semces August 16, 1993 Nudear Power Dwision 5 U. S. Nuclear Regulatory Commission ,

Attn: Document Control Desk Washington, DC 20555 i

Subject:

Beaver Valley Power Station, Unit No. 1 '

Docket No. 50-334, License No. DPR-66 Response to Information Request Dated July 13, 1993 i Spent Fuel Pool Rerack  ;

(TAC No. N84673) t This letter provides a response to your request for additional information regarding our proposed Technical Specification Change ,

Request No. 202, submitted by letter dated November 2, 1992. These-concerns are related to heavy loads and thermal / hydraulic parameters during replacement of the spent fuel pool storage racks. Attachment A l states each item followed by our response.  !

If you hava any questions regarding the attached response, please ]

contact Mr. Steve Sovick at (412) 393-5211. 1 l

Sincerely, j i

Mef Geor e S. Thomas-Attachment-cc: Mr. L. W. Rossbach, Sr. Resident Inspector.

Mr. T. T. Martin, NRC Region I Administrator Mr. G. E. Edison, Project Manager

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. ATTACHMENT A Beaver Valley Power Station, Unit No. 1 Technical Specification Change Request No. 202 RESPONSE TO ADDITIONAL INFORMATION REQUEST DATED JULY 13, 1993

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A. HEAVY LOADS Item 1 Discuss how the temporary crane, which is to be used to move fuel l racks complies with the guidelines of NUREG-0612, Section 5.1.1. (7) J which is shown below: 1 "The crane should be designed to meet the applicable criteria and guidelines of Chapter 2-1 of ANSI B30.2-1976, " Overhead and Gantry Cranes" and of CMAA-70, " Specifications for Electric Overhead Travelling Cranes." An alternative to a specification in ANSI B30.2 or CMAA-70 may be accepted in lieu of specific -

compliance if the intent of the specification is satisfied." l l

Provide the ultimate load this crane is able to hold and carry before any crane component or part fails.

Provide the necessary assurance that the crane will not fall in the event of an earthquake or that such fall will not violate any of the l criteria proposed in Section 5.1 (I-IV) " Recommended Guidelines" of l NUREG-0612.

Response 1 The proposed temporary crane satisfies all guidelines of NUREG-0612, Section 5.1.1(7) as explained in the following.

Applicability of 2-1 of the ANSI Standard to the temporary crane is j discussed below with the section notations taken from ANSI B30.2 where applicable to the temporary crane. Those sections which are not applicable are omitted for clarity.

2.1.1 Marking The temporary crane is designed for maximum lifted load and will only be used during reracking. This maximum lifted load will be painted on the crane and will also be marked on the control panel. The hoist has a higher load capacity than needed for the reracking.

2.1.2. Clearances 2.1.2.2 Clearance between the existing fuel handling l crane and the temporary crane is maintained by I mechanical linkage of the two units during rack installation / removal. During fuel shuffles in 3 the spent fuel pool, the temporary crane is  !

parked over the cask pit. l A-1

i ATTACHMENT A l

Beaver Valley Power Station, Unit No. 1  !

Technical Specification Change Request No. 202 RESPONSE TO ADDITIONAL INFORMATION REQUEST DATED JULY 13, 1993 l

, . ._- a w . .w. ;.y w m .. . ....c. i Response 1 (Continuedl 2.1.3 General Construction - Runways and Supporting Structure 2.1.3.2 Crane Runways -

The temporary crane will use the existing fuel handling crane rails. These rails are adequate to support the loads.

2.1.4 Crane Construction 2.1.4.1 Welding - The appropriate American Welding Code Sections are specified for welding procedures involving crane structural members.

2.1.4.2 Girders -

The crane meets the requirements of .

CMAA-70 design formulas where applicable. In l addition, finite element analysis has been j carried out. Safety margins meet the intent of ANSI N14.6 for heavy loads over critical areas. That is, the design margins are higher i than those required by CMAA-70. )

2.1.5 Cabs  !

Not Applicable.

l 2.1.6 Lubrication Lubricating points are in the hoist and possibly the crane l wheels. Access to the wheels is at walkway level. Access to the hoist is by means of a ladder at each end of the crane.

I 2.1.7 Footwalks and Ladders '

There are no service platforms required. Ladders meeting ANSI 14.3 are provided at each end of the crane, and a footwalk with appropriate measures to protect workers from falling, is provided l along the top of the crane.

2.1.8 Stops, Bumpers, Rail Sweeps, Girders The temporary crane travels on existing rails which have bumpers in-place (E-W travel). Trolley bumpers will be attached at the end of the girder carrying the motorized hoist (N-S travel).

However, the trolley will not be operated near the ends of trolley travel while carrying a rack.

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. ATTACHMENT A i

Beaver Valley Power Station, Unit No. 1 i Technical Specification Change Request No. 202 l RESPONSE TO ADDITIONAL INFORMATION REQUEST DATED JULY 13, 1993  !

pn++egr%~u~mM i Besponse 1 (Continuedl 2.1.9 Brakes  ;

The hoist unit of the temporary crane is supplied by Ingersoll Rand Co. and meets the requirements of ANSI-B30.2. The temporary  ;

crane is physically attached to the bridge of the fuel handling crane and travels at the same speed as the fuel handling crane.

2.1.10 Electrical l

The only electrical components are associated with the hoist ;

itself; these meet the ANSI requirements.

l 2.1.11 Hoisting Equipment '

The supplied main hoist is certified by Ingersoll Rand to meet applicable ANSI B30.2 requirements, OSHA requirements, and ANSI  ;

B16 which pertains specifically to hoists. The hoist is rated at  !

37.5 metric tons with a hoist design safety factor of 5. In the i event of loss of power, the hoist will hold the load.

With regard to ultimate load of the temporary crane, note that the maximum lifted load to be carried is 29,900 lb (existing fuel rack plus lift rig). The crane structural analysis and ultimate stress was carried out for crane dead weight plus an additional 32,000.lb.

When this load is applied, a minimum safety margin of 10.27 is predicted in the most critical location. -This minimum safety margin is a ' lower bound in that it is calculated using code minimum values for yield stress and ultimate stress. Actual tested values are usually on the order of 19% higher.than the minimums. Thus, the i minimum crane limit load (not collapse. load) is 328,640 lb. At this load, the crane is still capable of carrying. additional load, but at the expense of plastic deformation. The " collapse" load is considerably in excess of the above stated limit load.

The temporary crane will be physically connected to the fuel bridge crane providing E-W motive power over the spent fuel pool and the cask pit. This provides the required lateral stability to the crane. During fuel shuffles'in the fuel pool, the temporary crane.

will be parked over the cask pit which is protected by an impact'

t. shield and will be restrained to provide lateral stability.

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ATTACHMENT A Beaver Valley Power Station, Unit No. 1 Technical Specification Change Request No. 202 RESPONSE TO ADDITIONAL INFORMATION REQUEST DATED JULY 13, 1993

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Item 2 You plan to use the cask crane, which is " designated" as having a 125 ton capacity but presently rated at 60 tons, to move rack modules in and out of the cask pit. Discuss such movements with regard to the ]

following: l

a. Show that the paths followed by the cask crane when moving racks are " safe load paths," i.e., paths which I I

would not endanger dual trains of safe shutdown equipment, spent fuel, or the integrity of the spent fuel pool (SFP).

b. Explain the reason for derating this crane and how such.

derating affects the reracking process.

Response 2a The cask crane follows a straight line path from the outside of the Decontamination Building through to the fuel pool directly along the centerline of the cask pit. The cask crane at no time travels over the main spent fuel pool. The path does not travel over any equipment necessary for safe shutdown. During the rerack, the cask pit will be covered by an impact shield which will be used as a platform to change hooks from the cask crane (N-S travel) to the temporary crane (E-W travel). A similar approach was utilized to protect the new fuel vault when reracking Three Mile Island Unit 1 in j 1992.

I Response 2b DLC changed the reeving on the cask crane to increase hook speed.

The reeving change reduced the capacity of the crane to 60 tons. The cask crane derating does not affect the reracking since the rated load times the built-in safety factor of 5 is still more than 10 times the maximum load to be carried.

1 Item 3 l Provide a sketch of the remotely engageable lift rig. Explain what the ultimate load bearing capability of this rig would be in the  !

normal course of operation and in the event of the worst single l failure.

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( - ATTACHMENT A l

Beaver Valley Power Station, Unit No. 1 Technical Specification Change Request No. 202 RESPONSE TO ADDITIONAL INFORMATION REQUEST DATED JULY 13, 1993 l

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Response 3  ;

Figures 1 and 2 provide sketches of the remotely engageable " cam  ;

type" lift rig for the new racks. Similar rigs have been used during installation in all previous Holtec reracks. The rig has been analyzed using finite element modeling. The lifait load carrying ,

capacity based on reaching ultimate stress at a single point in the j structure is 271,890 lb. The maximum new rack weight to be carried i by the lift rig is 26,000 lb. Thus, the ratio between the maximum  ;

limit load and the design load for the rig is in excess of 10. A similarly configured rig is used for existing racks.

l As stated in Section 2 of the Licensing Report, the Holtec lift rig design has been utilized in numerous rerack projects, some requiring unusual underwater maneuvering of the rack. For example, at Zion early this year, this rig design was used to emplace racks in the I south end of the pool which had overhead access blocked by a 3 foot reinforced concrete overhang. The loads lifted using this genre of lift rig have been well in excess of 30 tons in some projects. Not a single incident of rigging instability or plastic deformation has ,

been observed in any of the hundreds of lifts and handlings which have been carried by Holtec's " cam" rig design.

The worst case failure scenario would entail failure (and total loss of load bearing capability) of one of the four lift rods. Depending on the load being lifted, such a failure may shift nearly the entire load to two rods, making the third remaining rod relatively redundant. However, even under this hypothetical scenario, uncontrolled lewtring of the load would not occur.  ;

Item 4 Explain the meaning of the phrase "--3 feet lateral free zone I clearance- " in paragraph 3 of page 2-10 of Holtec Report HI-92791.

Show how such clearance is to be maintained. Further, show either (1) that such clearance has the potential for avoiding any contact between racks in the SFP containing fuel with racks moving in and out of the SFP, or (2) that contact between racks will not cause damage I

to stored fuel with resulting excessive offsite doses or tendency to increase SFP criticality above the specified limit; also show that contact between racks during such movement will not damage the SFP.

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. ATTACHMENT A

- Beaver Valley Power Station, Unit No. 1 Technical Specification Change Request No. 202 RESPONSE TO ADDITIONAL INFORMATION REQUEST DATED JULY 13, 1993 i Response 4 The lateral free zone is defined as the minimum horizontal distance between the " shadow" of a heavy load being lifted above the racks in the pool and the periphery of the stored spent fuel. The lateral free zone is an empirical minimum separation distance which has been used in numerous previous rerack projects to provide an additional measure of defense-in-depth against consequences of a postulated rack drop. For example, the above requirement ensures that a rack being lifted adjacent to a fuel bearing rack must be moved away laterally before initiating any significant vertical lift.

The lateral free zone also ensures that any postulated drop of a heavy load in the pool will not lead to impact with or damage to the stored fuel. A drop from a considerable elevation (such as near the top of the pool) would, however, cause local damage to the liner.

Nevertheless, the overall structural integrity of the pool will not be impaired and precipitous loss of contained water in the pool will not occur. Under no drop scenario, no matter how hypothetical, is any criticality consequence with respect to the stored fuel indicated.

Item S Discuss whether the rotational or translational motion (vertical or horizontal) imparted to a heavy load (a rack) as a result of the worst single failure in the handling system will adversely affect i either spent fuel, the SFP or safe shutdown equipment. j i

l Response 5 The design of the lifting system guarantees that the worst postulated single failure in the rack handling system will not induce excessive horizontal movement. The rack handling system is designed using reduced allowable stresses as called out in ANSI N14.6 and d NUREG-0612. All components have a minimum safety margin of 10 based on the maximum lifted load.

The main link connection between the slings and the hoist is also j designed to have a minimum safety margin (allowable load / lifted load) j of 10.0. However, if one postulates failure of the lifting system during rack handling, analyses have been performed to demonstrate that damage to the pool structure will be limited as discussed in i Response 4. Thus the effect of the failure on spent fuel, the spent fuel pool, or on safe shutdown equipment precludes the possibility of a significant plant event.

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ATTACHMENT A I Beaver Valley Power Station, Unit No. 1 Technical Specification Change Request No. 202 RESPONSE TO ADDITIONAL INFORMATION REQUEST DATED JULY 13, 1993

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B. THERMAL-HYDRAULIC OUESTIONS 1

Item 1 i Holtec Report HI-92791, page 5-12, shows a temperature of 161*F for the SFP coolant in case la. Show that this presents no problem for the SFP.

I Response 1 The maximum pool bulk temperature of 161*F is calculated for the  ;

when adverse environmental and plant conditions occur '

scenario simultaneously. These conditions occur when the component cooling  !

water heat exchanger (which provides cooling to the SFP heat l exchanger) temperature has reached its design maximum of 100*F and l one cooling train is entirely unavailable. Even under this  !

condition, the peak value of 161'F is a transitory one; the pool water temperature crests to 161*F and then immediately begins to  ;

fall. The temperature of the enveloping reinforced concrete j structure lags the pool water temperature by several degrees and  !

several hours. As a result, the reinforced concrete structure temperature does not reach values which will cause degeneration of concrete strength.

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Even though the pool structure would experience the above mentioned peak temperature for a very short duration, its structural integrity has been demonstrated with 161*F as the driving temperature for thermal moments and shears. Section 8 of the Holtec report discusses this scenario.

All SFP piping, components and appurtenances are found to remain safe at 161*F.

It should be noted that the peak bulk water temperature in the BV-1 pool is actually lower than its peer plants under a similar set of hypotheses, indicating that the BV-1 cooling system's cooling capacity is above the norm for PWR systems.

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. ATTACHMENT A Beaver Valley Power Station, Unit No. 1 Technical Specification Change Request No. 202 RESPONSE TO ADDITIONAL INFORMATION REQUEST DATED JULY 13, 1993 J. .t.adswh%sisJW' ' i 4

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Item 2 The Updated Final Safety Analysis Report (page 9.5-4) states that the following systems are capable of providing makeup water for the spent fuel pool:

1. Primary grade water supply

2. Refueling water storage tank cooling systems

3. River water seismic Class I lines

4. Engine driven fire pump

5. Return of fuel building air conditioning condensate to the fuel pool Explain the following with regard to these systems:

a. What is the minimum flow rate expected from each system into the SFP?

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b. How long (approximately) will it take to initiate each system under normal circumstances?

c. Finally, can any of these systems be operated with onsite l power? Is any special arrangement required to operate l such systems when offsite power is not available?

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ATTACHMENT A i

. Beaver Valley Power Station, Unit No. 1 Technical Specification Change Request No. 202 RESPONSE TO ADDITIONAL INFORMATION REQUEST DATED JULY 13, 1993 M . . . :4%iv.u % ;,;W. ; -

Response 2 (a) (b) (c) ,

i Time To Onsite '

Minimum Flow Place in Service Power Primary Grade Water 50-100 gpm Within 30 minutes No Refueling Water Storage 50-100 gpm Within 30 minutes No Tank Cooling Systems  ;

River Water Seismic 300-400 gpm Within 30 minutes Yes(1) ,

Class 1 Lines Engine Driven Fire Pump 3 hoses @ Within 30 minutes N/A -

100 gpm each Return of Fuel Bldg. Insignificant Within 30 minutes No Air Conditioning To in short term Fuel Pocl (1) Only the river water system can be immediately operated with onsite power, no special arrangements are necessary to operate this system with onsite power. The power sources to the river water pumps are ensured by both onsite and offsite power. Upon-Inss of normal power, both pumps are automatically sequenced into  !

service. Each pump's discharge valve is similarly powered and .

I interlocked to open upon pump start.

i Item 3 It appears that decontamination is usually conducted in the decontamination facilities adjacent to the fuel building. With that in mind, discuss your plan to " hydrolase" racks in the SFP. How can maintenance of SFP coolant clarity be assured. Discuss your ability to deal safety with radioactive and other debris in the SFP as a i result of the racks hydrolasing. l A-9

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. ATTACHMENT A j Beaver Valley Power Station, Unit No. 1 Technical Specification Change Request No. 202 l RESPONSE TO ADDITIONAL INFORMATION REQUEST DATED JULY 13, 1993

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Response 3  !

I Preliminary decontamination of existing fuel racks will be performed in the SFP. This entails dislodging adherent debris using special  !

underwater brushes, and hydrolasing while the rack is submerged in the pool. The inside surfaces of the rack will.be hydrolased while the empty rack sits on the pool floor. The outside surfaces of the i rack will be hydrolased after the rack is lifted _and while suspended  ;

underwater from the temporary crane. As the rack is removed from the pool it will be rinsed, wiped as necessary and monitored for i radiation and contamination levels. l SFP coolant clarity is not anticipated to be a problem. Although some floor debris are expected to be dispersed while hydrolasing the lower internal rack surfaces, any decreased clarity is not expected to preclude operations since the internal surfaces of the rack will be used as a guide for manipulating the hydrolase tool. Past experience has indicated that hydrolasing the outside rack surfaces does not significantly affect pool clarity. The spent fuel pool coolant will be recirculated through filters during and after the-hydrolasing process to remove suspended particles from pool coolant.

The spent fuel pool cooling system filters, demineralizers and associated system _ components will be closely monitored during the operation. In addition, underwater radiation level monitoring will be performed as required during hydrolasing.

l Item 4 The UFSAR shows that the operating temperature of the fuel pool ion exchanger is 140'F, while the design temperature is 200'F. At what temperature does the resin in the ion exchanger start to deteriorate?

Response 4 Ion exchanger performance begins to decrease above 212*F, however, the resin does not begin to deteriorate until approximately 300*F.

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