ML20011F525

Documents Interpretation of Tech Spec 5.3.1.1 Re Design Features of Fuel Assemblies in Light of Issuance of Generic Ltr 90-02.Tech Spec Change Request Re Utilization of Dummy Fuel Rods or Open Water Channels Will Be Filed by 900420

ML20011F525
Person / Time
Site:	Three Mile Island
Issue date:	02/23/1990
From:	Hukill H GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
C311-90-2024, GL-90-02, GL-90-2, NUDOCS 9003060195
Download: ML20011F525 (2)

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, ~GPU Nuclear Corporation g

gf' Post Office Box 480 Route 441 South

-L e Middletown, Pennsylvania 17057 0191-  !

717 944 7621-TELEX 84 2386 - l o; Writer's Direct Olal Nurnber: i February 23, 1990 ,

C311-90-2024  ?

1 U.S. Nuclear Regulatory Commission .

' Attn:. Document Control Desk  !

Washington, DC 20555 j

Dear Sir:

Three Mile Island Nuclear Station Unit 1 (TMI-1)

Operating License No. DPR-50 7 Docket No. 50-289'

-Technical Specification Interpretation .;

Related to Dummy Fuel Rods 1

The purpose,of this letter is to document'an interpretation of Technical

• Specification 5.3.1.1 which deals with the design features of fuel assemblies. ,

Background.

.During . fuel cycle 7 operatien, monitoring of reactor coolant activity indicated. ,

that several fuel rods had failed in service. In order to reduce radioactive "

releases and occupational rediation exposure, GPUN planned for a full core off j

.. load to perform ultrasonic testing (UT) of-all fuel assemblies to identify the H

> > assemblies with failed rods.- Because the fuel assemblies installed during a;

s _ cycle 7 were:not a reconstitutable design, UT of. spent fuel was performed to

. identify candidates for replacement of the leaking fuel assemblies that were r not scheduled for discharge.

The.UTi of.the cycle 7 fuel identified four leaking fuel rods .in three fuel assemblies. Two of these were scheduled for insertion in cycle 8. A replacement assembly from the spent fuel pool was selected to replace one of the leaking r eemblies. No replacement could be identified for the other one without major core redesign. Based on this GPUN decided on February 1 to YO reconstitute the entire fuel assembly (referred to as recaging) by placing all.

non-failed fuel rods in a new skeleton assembly (cage). The two failed fuel k y_ rods were replaced with dummy stainless steel fuel rods to create a new recaged M gga.

48 fuel

~with success.

assembly. This technique has been used widely throughout the industry -

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$- A recaged fuel assembly with replacement dummy fuel rods is structurally and hydraulically equal,to a standard Mark-B7 fuel assembly. It can be used g gg E , interchangeably throughout the core. All fuel rod limits of a standard Mark-B7' fuel assembly are applicable to a recaged assembly, a

J The relosd core with the recaged assembh in 4ts N1oad location has been- l QQg analyzedL using a' pin-by-pin analysis methodology approved by the NRC. The

oso.ac . limits in the-CoreL0perating Limits Report (COLR) prepared in accordance with

.TS.6.9.5 are bounding for the reload core. 0j 0 GPU Nuclear Corporation is a subsidiary of General Public Ubbties Corporation #

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f y C311-90-2024 -2 Februa ry 23, 1990

. :i GPUN reviewed the Technical Specifications (TS) and concluded that no changes were necessary to permit replacement of. individual failed rods with dummy fuel rods. TS 5.3.1.1 indicates that fuel assemblies contain 208 fuel rods and that~ .

the details of fuel assembly design are described in TMI-1 FSAR Chapter 3.0.

Further, TS 5.3.1.6 indicates that " Reload fuel assemblies and rods shall conform to the design .... described in the FSAR." The recaged assembly continues to contain 208 rods in a 15-by-15 lattice. The insertion of two dummy fuel rods in place of the two defective fuel rods maintains the _.

structural and thermal-hydraulic characteristics of the fuel assembly described-in TS 5.3.1.1. The nuclear aspects of the fission cross-section change caused by the combination of 206 once-burned fuel rods and the two dummy fuel rods was analyzed in accordance with TS 5.3.1.6 and found acceptable. GPUN planned a special FSAR Update to address' the cycle 8 changes which includes recaged fuel. Therefore, it was concluded that the TS had been satisfied and that no TS changes were required.

On February 15, 1990, GPUN received Generic letter 90-02. In keeping with its policy of openness with the NRC on issues, GPUN shared the above TS interpretation with the NRC on February 21, 1990, and explained our interpretation. We committed to file a future TS Change Request (TSCR) consistent with the intent of Generic Letter 90-02 to further clarify the issue and to allow for more flexibility in choosing to utilize dummy fuel rods or open water ~ channels following removal of defective fuel rods.

Our TSCR will be filed no later than April 20, 1990.

Sincerely,

. D. ki 1 g Vice President & Director, TMI-1 HDH/CWS/spb:2024 cc: W. Russell.

F. Young T. Gerusky.

R. Hernan 1

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