ML20039B509

Requests Mod to Fuel Surveillance Program Workscope to Eliminate Destructive post-radiation Exam of Segment 2 Surveillance Element.Doe Funding Reduced for FY82.NRC Concurrence Requested by 820301

ML20039B509
Person / Time
Site:	Fort Saint Vrain
Issue date:	12/11/1981
From:	Lee O PUBLIC SERVICE CO. OF COLORADO
To:	Novak T Office of Nuclear Reactor Regulation
References
FSV-78A, P-81255, TAC-57625, NUDOCS 8112230169
Download: ML20039B509 (3)

Text

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PUBLIC SERVICE COMPANY OF COLORADO P.

O. BOX 840 DENVER.

COLORADO SO20s OSCAR H. LEE Fort St. Vrain u>

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Mr. Thomas M. Novak-

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Docket No.20-567

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Subject:

FSV Segment 2 Fus1 Surveillance

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Dear Mr. Novak:

In our letters of June 20, 1978 and June 23, 1978 (P-78103 and P-78103A respectively) the DOE funded Fort St. Vrain Fuel Surveillance Program was described.

The program scope includes nondestructive examination at the reactor site of five pre-characterized fuel elements from each of the initial core Segments 1-6 and a destructive

-post irradiation examination (PIE) in San Diego of one fuel element from Segments 1, 2, 4, and 6.

In our letter of January 24,1979 (P-79017) PSC stated that in the event DOE funding were to be withdrawn or substantially reduced, PSC would submit a modified program workscope to NRC for approval.

Overall HTGR technology funding by DOE has been substantially reduced since 1979. Allowing for inflation, the effective reduction in funding since 1979 has been nearly 40%.

Accordingly, funding for r

the FSV Fuel Surveillance Program has been reduced for FY-82, and a modification of 'the program is necessary.

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4 P-81255 Page 2 December 11, 1981 The purpose of this letter is to present to NRC a proposed modification to the fuel surveillance workscope.

PSC requests NRC approval to eliminate the destructive PIE of the Segment 2 surveillance element.

Nondestructive examination of five Segment 2 fuel elements at the site will be carried out as originally planned.

Based upon the following information, PSC believes that this request is reasonable and does not compromise the intent of the FSV Fuel Surveillance Program.

1.

The resul ts of the destructive examination of the surveillance element from initial core Segment 1 indicated that no inservice coated fuel particle failure occurred during Cycle 1 operation.

This observation is consistent with the very low level of circulating activity observed in the primary circuit during Cycle 1.

Cirrulating activities during Cycle 2 remained equal to or less than Cycle 1 levels and were virtually constant throughout the cycle, indicating that no inservice failure would be observed in a PIE of the Segment 2 fuel.

2.

The Segment 1 surveillance element received 174 equivalent full-powerdays (EFPD) exposure (about 10% of full design exposure).

The Segment 2 surveillance element has received only an additional 189 EFPD exposure.

Further PIE information at such low exposures is not expected to make a significant additional contribution to our understanding of coated fuel particle performance under normal operating conditions.

3.

Fuel Test Elements FTE-2, 4 and 6 each contain 88 FSV reference fuel rods.

These test elements are currently scheduled for destructive PIE under DOE funding for the large HTGR program.

The table below shows the estimated exposure (EFPD) that will be accumulated by the Surveillance elements and these three FTE's.

Element Removed Estimated

_ After Cycle Element EFPD Exposure 1

SURV-1 174 3

FTE-2 489 4

SURV-4 963 5

FTE-4 1089 6

SURV-6 1563 7

FTE-6 1689

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.e P-81255 Page 3 December 11, 1981 Accordingly, destructive PIE results for FSV fuel will still be available over a wide range of exposures if destructive

. PIE of the Segment 2 surveillance element is deleted.

'4.

The nondestructive-examination of the Segment 2 fuel elements at the site will. still be performed with the remaining FY-82 DOE funding.

These examinations will provide information on ' graphite behavior which cannot be obtained by monitoring plant operation in the same manner that information on fuel particle failure is obtained by munitoring circulating activity.

If you have any questions regarding this request, please do net hesitate to contact us. PSC requests that'your decision be provided by March 1,

1981 so that appropriate spent fuel shipping arrangements can.be made.

Very truly yours,

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O. R. Lee, Vice President Electric Production ORL/JS:pa i

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