ML18139B487

Nonproprietary Attachment to Util 810724 Ltr Re Proposed Changes to Tech Specs to Increase Enrichment Limit for New Fuel

ML18139B487
Person / Time
Site:	Surry, North Anna
Issue date:	07/24/1981
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18139B484	List: ML18139B483 ML18139B485 ML18139B486 ML18139B487
References
432, NUDOCS 8108240269
Download: ML18139B487 (5)

Text

e NON-PROPRIETARY

• ATTACHMENT TO LETTER DATED JULY 24, 1981 (Serial No. 432)

. Questions

• 1. Was a mass balance made of the iodine used in the iodine-pool DF experiments?

2*.- For the burnups greater than 33.000 MWD/MTU, is the DF valid?

3. What was thP. core inventory of Krvpton-85 at 20.000 MWD/MTU?

I

• Responses

1. Examination of Table 3-1, WCAP-7518-L indicates that the decontamination factor. DF, was determined by consideration of t:lemeasured a~ount of iodine in solution Ms., following a test and the measured amount of iodine that escaped from the solution, Mv, The DF. is then Mv Care was

• . Ms+Mv taken to assure that all the iodine not in solution, and hence must be in the vapor phase, was accounted for. Multiple scrubbers, tubing and teflon gaskets in the vapor collection *sp*ace were all analyzed for iodine to assure that it all was accounted for. Hence the measured values given

.in.th~ table sufficiently describe the. parameters.necessary for a DF

• calculation. ,

2. WCAP-7518-L considered total volumes of fission gases formed plus helium fill gases in the fuel pins for assembly arrays of 14 x 14 and 15 x 15 at burnuos up to 42,000 MWD/}ITU for a lead assembly, The maximum total gas for a lead assembly at this burnup was calculated to be [ , ]+ std. (a,c) cu. feet.

This analysis has now been extended to consider 17 x 17 standard fuel, 17 x 17 optimized fuel and 15 x 15 fuel. Expected volumes of gas expected in an assembly were calculated for various high burnuus. For these calcu-lations it was assumed that all rods in the lead assembly achieved the same burnup. In actual practice such is not the case; some pins in the assembly would have a lesser burnup and hence less *total fission gas would be produced. .

To assure a conservative calculation of -the amount of gas in an assembly, uncertainties were added to the calculated fission gas production.

Table 1 summarizes the calp1lated total gases expected for the vnrious assemblies. It may be soeH that for a 15 x 15 fuel array a total of

[ ... ~]".. std. cu. ft. of gas is cxpcctc(l at a burnup of 53,352 HWD/NTU. (a, c:

Lesser amounts of gas are expected in -lr x 17 and 17 x 17 optimized fuel assemblies at compnratiVl~ burnups.

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e e.

Since the experiments conducted in WCAP-75l8-L were**simulations of 15 x 15 fuel assemblies, the analyses were extended to cons_ider this greater volume of [ **. * ~+ ft. 3. * (a,c)

Figure 1 is a plot of the volume of gas and the expected pressure in a fuel pin for a 15 _x 15 assembly. The linear relationship between gas volume and pressure has been extrapolated to show an expected.

pressure of 1582 psi at the[~ ;,.J+ ft.3 volume. Figu~e 2 is a replot (a,c) of Figure 3-10 from the original WCAP. In this plot, the DF corresponding to a pressure of 1582 psi would be approximately 600.

These extrapolations indicate that the DF values of 100 assumed for. a fuel handling are valid for high burnup 'fuel, and are conservative.

• J. The core inventory of Krypton-85 at 20,000 MWD/MTU is 3.8 x 105 Curies.

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e TABLE 1

.e VOLUME OF GAS IN LEAD ASSEMBLY FOR VARIOUS FUEL TYPES Burnup Volume of gas Assumed in assembly

)_ype of Fuel (MWD/MTU) (ft.3 at STP)

+

15 X 15 I

• 17 x 17 Standard 17 x 17 Optimized Fuel

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