ML19320C214

Submits Status & Schedule for Completion of Mark 1 Program Mods at Facility Per NRC Telcon Request

ML19320C214
Person / Time
Site:	Cooper
Issue date:	07/10/1980
From:	Pilant J NEBRASKA PUBLIC POWER DISTRICT
To:	Ippolito T Office of Nuclear Reactor Regulation
References
LQA8000336, NUDOCS 8007160440
Download: ML19320C214 (2)

Text

- .

LQA8000336 GENERAL OFFICE Nebraska Public Power District a

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July 10, 1980 bireccor, Nuclear Reactor Regulation .

Attention: Mr. Thomas A. Ippolito, Chief -

Operating Reactors Branch No. 2 Division of Operating Reactors U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Mark I Containment Program Modifications Cooper Nuclear Station NRC Docket No. 50-298, DPR-46

Dear Mr. Ippolito:

This letter is written per a NRC staff telephone request to provide the status and schedule for completion of the Mark I Program modifications at Cooper Nuclear Station. The following Mark I Program modifications have been completed:

1. Torus columns reinforced and anchored.

2. Implemented drywell-wetwell pressure differential.

3. Installed vent header pool swell deflectors.

4. Truncated downcomers.

5. Installed downcomer bracing.

6. Insta11ea S/RV T-Quenchers and supports.

7. Rerouted anc resupported S/RV discharge lines in the wetwell (8 total) .

8. . Installed larger S/RV discharge line vacuum breakers in the drywell (16 total).

9. Modified / verified 46 piping supports on the drywell S/RV discharge

. lines.

The following modifications are being planned for the Spring 1981 refueling outaa,e:

1. Installation of torus miter joint saddles. ON

2. Modification of various torus internal structures, including the following: jo 8007160

Mr. Thomas A. Ippolito July 10,1980 Page 2

a. Ring girder (reinforce)

b. Monorail (reinforce)

c. Platform (reinforce)

d. HPCI, RCIC spargers (resupport)

e. Veat header supports (reinforce)

3. Modification of approximately 45 redesigned piping supports on the drywell S/RV discharge lines.

The following modifications will be performed prior to June 1982:

1. Install additional supports on the piping attached to the torus.

2. Modification of approximately 14 redesigned piping supports on the S/RV discharge lines in the drywell.

Modifications to the piping attached to the torus shell is pending the results of the torus analyses which are required as input to the piping analysis. The final torus analyses are pending the issuance of General Electric's " Load Definition Report," NED0-21888, Revision 1. This report is being revised to incorporate changes required by Revision 1 of the NRC acceptance criteria which was issued in February,1980.

In order to optimize the dose received by workers, installation of the S/RV piping supports in the drywell is being perfomed in phases. There are 105 supports that require attention to complete the Mark I Program modifications. There were 46 supports that were either modified or verified in the first phase. These supports represent the most beneficial locations for reducing calculated stresses based on the newly defined loads. Supports in the next two phases will be selected based on the same criteria.

In order to verify that there are no safety related deficiencies at CNS, an inspection of all structures calculated to experience excessive loading was performed prior to any support modifications. No buckling, cracking, wrinkled paint or other evidence of yielding was found, thereby indicating that there is a large degree of conservatism in the new load definition.

Modifications to the piping act to greatly increase the inherent safety margins. The conclusion of assessments to date, including in-plant verifi-cation of physical evidence, is that incorporation of the modifications in

~ the above manner provides for safe continued operation.

If you should require additional clarification, please contact me.

Sincerely, b4.

. Pilant Director of Licensing and Quality Assurance JDW/cmk