NLS8900427, Submits Clarification of Util 890712 Response to Suppl 3 to NRC Bulletin 88-008, Thermal Stresses in Piping Connected to Rcs. Evaluation Determined That No Sys Susceptible to Temp Stratification or Oscillations

Submits Clarification of Util 890712 Response to Suppl 3 to NRC Bulletin 88-008, Thermal Stresses in Piping Connected to Rcs. Evaluation Determined That No Sys Susceptible to Temp Stratification or Oscillations

ML19332D549
Person / Time
Site:
Issue date:	11/22/1989
From:	Kuncl L NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
IEB-88-008, IEB-88-8, NLS8900427, NUDOCS 8912040132
Download: ML19332D549 (7)

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GENERAL OFFICE t

Nebraska Public Power District

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6L58900427-November 22, 1989 i

l U.S. Nuclear Regulatory Commission

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Attention: Document Control Desk

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Subject:

Clarification to the Response to NHC Bulletin 88-08 f

Cooper Nuclear Station

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NRC Docket No. 50-298, DPR-46 l

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References:

1) NRC Bulletin No. 88-08, Thermal Stresses in Piping Connected to Reactor Coolant Systems, dated June 22, 1988

2) HRC Bulletin No. 88-08, Supplement 1, Same subject, dated June 24, 1988

3) HRC Bulletin No. 88-08, Supplement 2,

same subject, dated August 4, 1988

4) NRC Bulletin No. 88 08, Supplement 3, same subject, dated April 11', 1989

5) Letter, NLS8800460 frore L. G. Kuncl to USNRC, dated 9/23/08, Response to NRC Bulletin No. 88-08 is

6) Letter NLS8900251 from L. G. Kuncl, dated 7/12/89, Supplemental l-Response to NRC Bulletin No. 88-08

7) Telecon between M. Boyce, K. Done, M. Henry (NPPD) and P.

O'Connor and S. Lee (NRC), dated 10/2/89, same subject a.

. Gentlemen:

The NRC requested utilities, in NRC Bulletin 88-08 and Supplements 1 and 2, to review systema connected to the Reactor Coolant System (RCS) to determine l:

whether unisolable sections of piping connected to the RCS can be subjected to stresses from temperature stratification or temperature oscillations due to the leakage of " cold" fluid into the RCS.

In addition to this review, the NRC also requented that any unisolable piping which could be subjected to stresses

,r caused by temperature stratification or temperature oscillations, be examined nondestructively _ to provide assurance that there are no existing flaws and that a program be implemented to provide continuing assurance that unisolable sections of piping will not be subjected to these thermal stresses.

. References 5 and 6 contain the results of the District's review and nondestructive examination of unisolable sections of high pressure piping systems connected to the RCS that could allow leakage of " cold" fluid into the

" hot" RCS fluid.

The District has, therefore, previously addressed NRC Bulletin 88-08 and Supplements 1 and 2.

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Supplement 3 to NRC Bulletin 88-08 identifies a different source of thermal

, stresses, which is the leakage of " hot" fluid out of the RCS through a valve packing gland leakoff connection. This concern was not specifically addressed

'in References 5' ' and 6.

This additional source of thermal stress was

. identified to the District in a telecon with the NRC (Ref erer.ce 7), which clarified the concerns of supplement 3.

As a result, this clarification to

.the supplementai response to NRC Bulletin 88-08 is being provided.

In. response to the additional concerns identified in Supplement 3,

as clarified by the NRC in Reference 7, the District conducted a review of al*

CNS systems connected to the RCS.

This review resulted in the identificatir of. the. following systems which contain valves with packing gland leakoff.

connections in the section of the system which is unisolable from the RCS.

These-systems are:

1.

Main Steam (MS) System 2.-

Main Feedwater (RF) System g

3.

High Pressure Coolant Injection (HPCI) System I

4.

Reactor Core Isolation Cooling (RCIC) System p

5.

Residual Heat Removal (RHR) System 6.

Reactor Water Cleanup (RWCU) System 7.

Core Spray (CS) System-i:

L The Main Steam System, Main Feedwater System and Reactor Water Cleanup System are operating during normal plant operation.

Therefore, these systems will not be' subjected lto the cyclic thermal stresses, which result from the leakage of " hot" water out of the RCS, as discussed in NRC Bulletin 88-08 Supplement 3.

I' The only systems with a potential for thermal induced stresses caused by the E

, leakage of " hot" water out of the RCS through a valve with a leakoff connection, are the HPCI, RCIC, RHR and CS systems.

A review of the valve drawings and procurement contracts for the valves in the unisolable sections of the HPCI,

RCIC, RHR and CS Systems was

-perform 3d.

From this review it was found that there were twelve valves with' a packing gland leakoff connection in the unisolable sections of these systems.

These twelve valves are listed in Attachment 1, A detailed review of the HPCI, RCIC, RHR and CS Systems' flow drawings, isometric drawings and surveillance procedures was then performed to determine the susceptibility of the identified valves in Attachment 1.

A summary of the results of this review are listed in Attachment 1.

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3 The results of the District's review conducted in responce to Supplement 3 to Bulletin 88-08, and an analysis of those results, is provided below.

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1.

All valves,that are part of the primary containment local leak rate testing, are. tested every refueling outage.

The allowable leakage through these valves ' is very small.

Therefore, any significant. leakage through these valves would. have been noticed and corrected during the performance, of the local leak rate test.

.(HPCI-A0V-A018, RCIC-A0V-A022, and RHR-MOV-M018).

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2.

The susceptibility of piping with valves installed in a vertical run, is; negligible.

This is based upon the fact that the stratification phenomena described in Supplement 3 to NRC Bulletin should not exist in a vertical line.

(HPCI-A0V-A018, RHR-AOV-A060A & B, RHR-MOV-M018, CS-V-14 A & B) 3.

Valves RHR-V-81A, and RHR-V-81B, which are locked open during normal plant operation, are very near the Reactor ' Recirculation 1

(RR) System tie-in_(less than 3.5 ft.).

As a result, the fluid temperature at. the.. valves will be essentially the same temperature as.the RR System fluid temperature and thermal t

stratification should not be a concern.

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Several valves are~ located a significant distance from the RCS

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tie-in (greater than.30').

As a

result, the RCS fluid temperature at these valves will be very close to the ambient temperature even if there is packing leakage, and therefore, thermal. stratification should not exist.

(RHR-A0V-A068 A & B, CS-A0V-A013 A & B, RHR-MOV-M018) 5.

The manual valves in the -leakoff connection lines for several of the valves:in question are closed during normal plant operation.

.i Therefore,. there should be no leakage through these leakoff connections.

(RHR-V-81 A & B,.RHR-V-88, CS-V-14 A & B) 6.

~ The leakoff connection for valve RHR-MOV-M018 has been plugged as part of a design change modification to the plant. As a result, there would be no ' leakage through the leakoff connection for valve RHR-MOV-M018.

The District has determined, based on the results above, tnat there are no systems which are susceptible to temperature stratification or oscillations i

brought on by the leakage of " hot" water out of the RCS through a valve

. packing. gland leakoff connection, and that no additional programs are required

.to monitor for these conditions.

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" 3i you have/any; questions regarding this' response, please contact my. office.

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' (Sincerelyb F

M, L..G.

Kuncl

' Nuclear Power Group Manager

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ES. Nuclear Regulttory Consniccion November 22, 1989 Pag) 5 i

STATE OF NEBRASKA)

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L. G. Kuncl, being first duly sworn, deposes and says that he is an authorized i

representative of the Nebraska Public Power District, a public corporation and political subd!. vision of the State of Nebraska; that he is duly authorized to submit this response on behalf of Nebraska Public Power Distr)ct; and that the

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statements contained herein are true to the best of his knowledge and belief.

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/ L. G. Kuncl l

I Subscribed in ray presence and sworn to before me this _ SQ/Mi day of h 8tt3 1909.

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p-g ATTACH!8ENT 1 6-c

' UNIS01ABLE VALVES WITH LEAKOFF Coh3ECTIONS OPERATING VALVE NO.

DRAVINGS STATUS t f-um15 1.

HPCI-AOV-A018 B6R 2044 CMSED

1. - Valve ' tested during performance of PC IJJtT.

JELCO 2509-2 2.

valve is located in a. vertical.run of piping.

2.

RCIC-A0V-A022 B&R 2043 CLOSED 1.

Valve tested during performance of PC JELCO 2509-1 LIJtT.

3.

RHR-V-81A B&R 2040 IDCKED 1.

Valve located less than 3.5' from RCS JELCO 2510-4 OPEN 2.

Leakoff connection valve is closed during normal operation.

4 RHR-V-81B B&R 2040 IDCKED 1.

Valve located less than 3.5' from RCS JELCO 2510-3 OPEN-2.

Imakoff connection valve is closed during normal operation.

5.

RHR-V-88 B&R 2040 LOCKED 1.

Leakoff connection valve is closed JEILO 2510-1 OPEN durin6 normal operation.

6.

RHR-AOV-A068A B&R 2040 CIDSLD 1.

Valve is located in a vertical run of JELCO 2510-4 piping.

2.

Valve is located -75' from the RCS.

7.

RHR-A0V-A068B B&R 2040

'CIDSED 1.

Valve is located in a vertical run of-JELCO 2510-3 piping.

2.

Valve is located -75* from the RCS.

8.

RHR-MOV-MOIS B&R 2040 CIDSED 1.

Valve tested during performance of PC '

JELCO 2510-1 LIRT.

2.

Ieakoff connection has been plugged under a minor design change.

3.

Valve is located in a vertical run of piping.

4 Valve is located ~80' from the RCS.

9.

CS-V-14A B&R 2045 IDCKED 1.

W.1ve located in a vertical run of JE140 2501-1 OPEN piping.

2.

Imakoff connection valve is closed during normal operation.

PAGE 1 OF 2

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ATTACHMENT 1 UNISOIABLE VALVES WITH LEAKOFF CONNECTIONS OPERATING VALVE NO.

DRAWINGS STATUS COMMENTS i

10.

CS-V-14B B&R 2045 LOCKED

1.. Valve located in a vertical run of 2

JELCO 2501-1 OPEN piping.

2.

Leakoff connection valve is closed during normal operation.

11.

CS-A0V-A013A B&R 2045 CIDSED 1.

Valve is located ~30' from the RCS.

JE1EO 2501-1 12.

CS-A0V-A013B B&R 2045 CIDSED 1.

Valve is located ~30' from the RCS.

JEILO 2501-1

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