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f T H E C L E V E L A N DE L E C T ri i C i L L U i? i M /M N u C o m P ' E Y |

P.o. Box 5000 - CLEVELAND, oHlo 44101 - TELEPHONE (216) 622-9800 - |LLUMINATING BLDG. - 55 PUBLICSQUARE

- Sen'ing The Best Location in the Nation

MURRAY R. EDELMANVICE PRESIDENTNUcuAR June 21, 1983

PY-CEI/NRR-0054 L

Mr. B. J. Youngblood, ChiefLicensing Branch No. 1Division of LicensingU. S. Nuclear Regulatory CommissionWashington, D. C. 20555

Perry Nuclear Power PlantDocket Nos. 50-440; 50-441Mechanical Engineering BranchQuestion Nos. 210.9, 210.10 and 210.11

Dear Mr. Youngblood:

This letter and its attachments provides our response to your letters datedDecember 14, 1982 and April 1, 1983 requesting additional information on thesafety relief valve piping and quencher device (Questions 210 9 and 210.10)and safety-related piping supports (Question 210.11).

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Attachment 1 to this letter provides the evaluation of lateral instabilityof safety-related piping supports with pinned-pinned end connections subjectedto non-cyclic compressive loadings, in response to your April 1, 1983 letter.Based on the additional analysis and evaluation performed, we have determinedthat lateral instability will not occur and no corrective measures are required.

Draf t FSAR respcnses for the three Mechanical Engineering Branch questionsare attac:cd. These will be included in Amendment 12 to the Perry FSAR.

If you have any questions, please let me know.

Very truly yours,

h

b/Murray R. EdelmanVice PresidentNuclear Group

MRE:kh

cc: Jay Silberg, Esq.John StefanoMax Gildner j

Attachments

8306240186 830621 || |PDR ADDCK 05000440A PM

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Atttchment 1PY-CEI/NRR-0054LJune 21, 1983

EVALUATION OF LATERAL INSTABILITYOF SAFETY-RELATED PIPING SUPPORTS

-In a letter dated April 1, 1983, additional information was requested

regarding safety-related piping supports for Perry Nuclear' Power Plant-(Units

1 & 2). Specifically requested was identification of corrective measures that

would be taken to properly account for the lateral instability of all

safety-related piping supports with pinned-pinned connections subjected to

.non-cyclic compressive loadings. The letter specifically pointed out that

lateral instability should be considered for several vertical piping supports

on.the Low Pressure Coolant Injection piping system located above the

. suppression pool surface, when subjected to pool swell upward drag loadings

during a design basis LOCA event.

Based on the questions raised in the April 1, 1983 letter, we have performed

additional analysis and evaluation and have determined that lateral

instability will not occur when piping supports with pinned-pinned connections

are' subjected to non-cyclic compressive loadings.

The concept of' structural instability is discussed in a number of technical

references including Theory of Elastic Stability by Timoshenko and Gere

(p. 83) and Elementary Structural Analysis by Norris and Wilbur (pp. 577-581).

The most relevant points are as follows:

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JA. stor a given length L of a bar.between the pinned connections and the

laterallrestraining spring constant k, there is a critical value of

compressive load P 1such that the system would be unstable-for aer

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load' equal.to or larger than the critical load. 13ua critical load

is given'by:

P = kLcr

B. The magnitude.of the' critical load is independent of the initial

disturbance of the system.

When a horizontal pipe supported from above by rods with pinned

connections is subjected to upward forces, the supports may be

loaded in compression. This. situation is related to-the classical

structural instability problem. It is' generally believed that the

pipe itself provides considerable ' lateral elastic restraint to help

prevent-lateral instability. On the other hand, the compressive

loads on the pinned pinned hangers may.be sufficient to warrant

further consideration relative to lateral instability. The piping

support lateral instability issue was viewed in two ways:

1. For the design upward non-cyclic loads, whether the horizontal

stiffness of the pipe and the support system is sufficient to

prevent the system from moving laterally uncontrolled;

2. For the piping support scheme, as designed, whether the non-

cyclic compressive loads on pinned-pinned connected supports

would reach the critical loads for the system to be unstable.

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> - All safety-related systems in the area within-30' above the El. 593'4" pool~

surface were identified and evaluated for potential-lateral instability

, problem. |The evaluation considered pipe layout, locations of pinned pinned

connected vertical supports and' lateral restraints'in the vicinity..

It was concluded |that:the LPCI. system, also identified a's 1E12G15 and lE12E14

analysis subsystems, is_the worst. case for consideration of lateral instabil--

ity, since these subsystems.have the longest horizontal run above the pool.

(These subsystems have_ sizable portions of pipe' supported by pinned pinned

connected struts and portions are subjected to maximum-sustained pool swell

drag loads.). Since it was determined that the pertinent parameters were worst

case for the LPCI system, an analysis of these subsystems was first conducted.

Analytica1' computation of' relevant data for the LPCI subsystems was performed

to determine whether the system as designed is actually stable for the pool

swell design ~1oad. The assumptions used in the analysis of LPCI subsystems

- were the following:

1. The pool swell load is the only upward.non-cyclic load that induces

compressive force on the pinned pinned connected supports.

2. -The worst cases of pool swell impact and/or drag load for these subsystems

were used.

3. The snubbers on the pipe sections subjected to pool swell drag load are

assumed to be inactive.9

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4. The entire piping and supports were treated as a system. That is, the

loads on all pinned pinned connected supports were accounted for simulta-

neously.

5. The piping stress analysis model was used so that the actual lateral

restraining stiffnesses of the system, including the effect of supports

and the pipe itself, were accounted for.

The method of analysis used was based on the following principles:

1. "If a system is displaced slightly from its equilibrium position, does it_

tend to return to its original position or does it tend to displace

further when the disturbance is removed? If it returns, the system is

stable; .if it displaces further, it is unstable." (Ref. Norris and

Wilbur, p. 578)

2. The critical buckling loads are independent of the initial disturbance.

(Ref. Norris and Wilbur, p. 579)

3. The structural instability problem can be characterized mathematically as

an eigen value' problem with the eigen vector representing the mode of

buckling and the corresponding eigen value representing the critical load

ratio.

4. The eigen value problem can be solved by a successive approximation

method.

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2These principles were employed and TPIPE computer analytical model of the

: piping' system was used for the computation. A successive approximation

technique was used. The stability character illustrated'in principal No. 1

above was' observed. The' iterative solutions' converged to buckling modes.with

associated critical load ratios greater than 1.0 for:both subsystems analyzed.

Thus, the subsystems are stable.

As'previously stated, all appropriate. safety-related systems were identified

and evaluated. Since the pertinent parameters for lateral instability

_ questions were determined to be worst case in the LPCI subsystems 1E12G15 and

1E12G14; and, since detailed analysis of these subsystems indicated no in-

stability problems, the necessity for detailed analysis of the remaining

systems is precluded.

From this analysis.and evaluation we have determined that no corrective

measures are required to account for lateral instability of safety-related

piping. systems,

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210.9 In recent discussions with the applicant, it has become apparent to

the staff that the safety-relief valve (SRV) piping in the

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suppression pool are provided with horizontal quencher supports that.

are welded directly on the piping. In the staff's opinion, the

welded attachment could cause excessive localized bending stresses

and harmful thermal gradients in the piping following actuations of

the safety-relief valves. Furthermore, the relatively large number

of stress cycles .could result in fatigue failure in the piping. The

applicant is requested to provide detailed analyses of the welded

attachment to verify that the structural integrity of the piping and

the quencher support capabilities are not compromised.

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Response

The response to this question will be provided by June 30, 1984.

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~- 210 :10 The quencher' device is classified as an ASME Code Class 3 component.

Provide the basis for assuring that the quencher device has been

adequately designed for all applicable stresses resulting from the.

actuation of the safety-relief ' valves: including localized bending~

stresses and thermal gradients.

Response

- Thermal gradients and localized stresses are considered in the fatigue factor

used in the stress for ASME Code Class 3 piping components. The stresses at

critical locations in the quencher configuration have been evaluated and

determined to be within the ASME code allowable stresses for the quencher

design.

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i210.11 Identify corrective measures that will be taken to properly account '

for the lateral instability _of all safety-related piping supports

.with pinned-pinned end connections-subjected to non-cyclic compres-it

*sive loadings.

Response

.

In a letter dated April 1, 1983, additional information was requested

regarding safety-related piping supports for Perry Nucicar Power Plant (Units

1 & 2). Specifically requested was identification of corrective measures that

would be caken to properly account for the lateral instability of all

safety-related piping supports with pinned-pinned connections subjected to

! non-cyclic compressive loadings...

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Additional analysis and evaluation have been performed and submitted in a

letter dated June 21, 1983. It has been determined that lateral instability,

will not occur when piping supports with pinned-pinned connections are sub-,

jected to non-cyclic compressive. loadings. Therefore, no corrective measures '

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are required to account for lateral instability of safety-related piping.

systems.

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