ML20197F854

Forwards Safety Evaluation Supporting Util 820407 Request for Power Level Increase & Increase in Burnup.Info in DC Cook Unit 2 Potential Radiological Consequences of Incidents Involving High Exposure Fuel Supports Request

ML20197F854
Person / Time
Site:	Cook, 05000000
Issue date:	12/10/1982
From:	Houston R Office of Nuclear Reactor Regulation
To:	Lainas G Office of Nuclear Reactor Regulation
Shared Package
ML20197F859	List: ML20197F854 ML20197G279 ML20197H750 ML20210P567 ML20210P638
References
FOIA-86-78 TAC-48290, NUDOCS 8212160613
Download: ML20197F854 (4)

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DISTRIBUTION Docket F11e AEB R/F' _

JMitche11 DEC 101982 WPasedag Plant File Doctet No.: 50-316 MD40 rat!DUM FOR: Gus Lainas Assistant Director for Operating Reactors Division of Licensing F809.: R. Wayne Houston, Assistant Director for Radiation Protection Division of Systems Integration SUDJECT: D. C. COOK UNIT 2 CYCLE 4 RELOAD ANALYSIS: POWER '

IEREASE AND EXTENDED BURNUP TAC f48290

.i By letter number AEP:HRC:0637A dated April 7,1982, which was supplemented numer-

- ous times, Indiana A Nichigan Electric Company requested approval for a power level increase and an increase in burnup for D.C. Cook Unit 2. The power level of the  ;

new Safety Analysis is 3425 MWt ; the burnup is 30,000 mwd /HTU core average with

- a burnup of the peak assettly of 43,000 Mnid/MTU. .

A report, E-NF-82-90, entitled "D.C. Cook Unit 2 Potential Radiological Conse-  !

quences of Incidents Involving High Exposure Fuel" was submitted in the Cook Unit .

2 docket by letter dated Novetter 24, 1982. This document, which was prepared in l response to cuestions by the staff, considered the effects of higher burnup, as well as the power level increase, on the potential consequences of accidents. The licensee considered the following factors relative to the analysis of record: The i[

potential for increased fuel failure, an increase in the fraction of volatile radio- ^

active fission products in the gap of the fuel rods, a charge in the isotopic mix of fission products in the core, and the decontamination factor.for iodine in fuel pool accidents.

The Accident Evaluation Branch (AER) has reviewed the licensee's submittal. and has concluded that if the licensee's evaluation of the extent of fuel failures -

or more importantly the absence of fuel failures - is correct,' there.are no identified issues that would preclude the increase in either burnup or' power -

level. Confirmation of the level of fuel failures assianed in the licensee's .

w - evaluation is within the scope of the reviews of the Core Perfoimance and' Reactor Systens Branches. The doses fran a postnisted fuel hand. ling accident P inside containment were independently assessed by AEB as discussed in the enclosure.

Original signed by R. Fayce Houston _

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R. Wayne Houston, Assistant Director

_ lElloj0/4 3 / for Radiation Protection Division of Systems Integration

Enclosure:

As stated cc: R. Pattson L. Rubenstein *See Prehious Concurrence Sheet f]l

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Safety Evaluation D.C. Cook Unit 2 Cycle 4

Background

By letter dated April 7,1982, as supplemented, Indiana & Michigan Electric Company, the licensee for D.C. Cook Unit 2, requested approval andfor includes Cycle 4 operation. This cycle will ba at an uprated power of 3425 MW:

burnup beyond the traditional value to 30,000 mwd /MTU core average with a peak module burnup of.43,000 mwd /MTU.

24, 1982, report number XN-NF-82-90, "D.C. Cook By letter dated NovemberUnit 2 Potential Radiological consequences This of Incidents In Exposure fuel" was submitted on the D.C. Cook Unit 2 docket. '

report covers calculations by Exxon Nuclear Corporation of the radiological consequences of accidents at the higher power level for the above burnup i 0

limit.

Evaluation .

The licensee's submittal was reviewed to assure that all the requested 1 That is, changes in isotopic mix of nuclides effects were considered. {

available for release following accidents, the potential for failure of fuel following accidenj:s, pool decontamination factor changes due to rod internal pressure charges, and release of volatile fission products

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into the pellet-clad gap. With the exception noted below, all the factors were considered in the submittal in a manner to show that the mitigation features and the design of the plant are adequate to control ,

the radiological consequences of accidents. ,

The licensee did not evaluate the radiological consequences of the locked rotor, steamline break or rod ejection accidents since the calculations

' This is acceptable, provided the absence of fuel show no fuel failures.

failures is confirined by other revie'ws.

The evaluation of the fuel handling accident inside containment was per .

fomed by Exxon in accordance with the assumptions of Regulatory Guide 1.25, even though the conditions at the er.d cf cycle 4 will be beyond the basis Since. no justification for continued conservatism

- stated in the. Guide. ,

of these assumptions was'provided by the licensee, the staff independently evaluated this accident ~.

The missing justification concerns the fraction of noble gas and iodine Report assumed to be in the pellet-clad gap "D.C. of theCook highest power inodule.

Unit 2. Cycle 4 Safety number XN-NF-82-37(P) Supplement 1 >

Analysis Report," shows that the highest power module is a first cycle module. Therefore, the case to be considered is- a module at about 15,000 mwd /MTU at the highest ' allowable linear heat generation rate, about 13 kW/ft. inFor model this case, calculations based on the fission gas release '

the proposed ANS 5.4 standard shows gap fractions loss than 30% of of 85Kr about 10% of 1311 and less 'than 10% of all other radionoble gases Therefore, it is not necessary to consider up to 30%

and radiciodines.

of these nuclides within the gap, as the licensee did for the fuel handling The assumptions used by the staff and the accident outside containment.

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O results of the calculation are given in Table I. The results show that the delay to 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> from shutdown and site related parameters are adequate to l mitigate the consequences of this accident.  :

Conclusion The licensee and the staff have considered the factors dependent upon .

power level (to 3425 MWt) and burnup (to 30,000 mwd /MTU core average for peak module 43,000 mwd /MTU) that impact the radiological consequences of accidents. Assuming that the licensee's evaluation of the level of fuel failures (or absence of fuel failures) is confirmed, there are no identi-fied issues that would preclude the higher power level or the extended burnup. -

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Table 1 Assumptions for and Results of Calculation of the Fuel Handling Accident Inside Containment Power level 3425 MWt Peaking factor 2.1 Fuel failures 1 module of 193 l No filtration i r Shutdown. time 100 hrs Meteorological factors * (sec/m3) l Exclusion Area Boundary 0-2 hours 2.1 x 104' Low Population Zone 0-8 hours 1.8 x 10~5 Thyroid - Whole Body Doses (Rem)

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