ML20148J303

Application for Amend to Licenses NPF-37,NPF-66,NPF-72 & NPF-77,reflecting Latest Rev of Waste Gas Decay Accident Dose Calculation

ML20148J303
Person / Time
Site:	Byron, Braidwood
Issue date:	06/09/1997
From:	Hosmer J COMMONWEALTH EDISON CO.
To:	NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20148J310	List: ML20148J303 ML20148J323
References
NUDOCS 9706170099
Download: ML20148J303 (4)

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Commonwealta Edhon Company 1400 Opus Plxe f> owners. Grove. lL NFil 5-5'01 Qune 9 -1997 5

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attention: Document Control Desk i

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SUBJECT:

Application for Amendment to Facility Operating Licenses Byron Station Units 1 and 2 Facility Operating Licenses NPF-37 and NPF-66 NRC Docket Nos. 50-454 and 50-455 Braidwood Station Units 1 and 2 Facility Operating Licenses NPF-72 and NPF-77 NRC Docket Nos. 50-450and 50-459-i Waste Gas Decay Tank Rupture Accident Dose l

Pursuant to 10 CFR 50.90, Commonwealth Edison (Comed) proposes to amend Facility Operating Licenses NPF-37,66,72, and 77 to reflect the latest revision of the waste gas decay tank rupture accident dose calculation. During preparation of the resulting UFSAR change, an unreviewed safety question was identified. In accordance with the provisions in 10 CFR 50.59(a)(2)(iii), this change requires NRC stalTreview and approval per the provisions of 10 CFR 50.90 because the consequences of an accident previously evaluated in the safety analysis are increased.

The following Attachments have been developed in support of this proposed change:

Attachment A Description and Safety Analysis j

Attachment B Marked Up Copy of Proposed UFSAR Change Attachment C Evaluation of Significant Hazards Considerations Attachment D Environmental Assessment Statement

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This proposed changes have been reviewed and approved by Comed Onsite and Offsite l

Review in accordance with Comed procedures. Comed has reviewed the proposed changes in accordance with 10 CFR 50.92(c) and has determined that no significant hazards considerations exists.

9706170099 970609 PDR ADOCK 05000454 P

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a U S. NRC June 9,1997 To the best of my knowledge and belief, the statements contained above are true and correct.

Comed is notifying the State ofIllinois of this application for amendment by transmitting a copy of this letter and its attachments to the designated state oflicial.

Please address any comments or questions regarding this matter to Marcia Lesniak, Nuclear Licensing Administrator, at (630) 663-6484.

Sincerely,

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OFFICIAL SEAL -

4 JACQUELINE T EVANS!{

John B. Hosmer NOTARY PutOC, STATE oF ILLies004 h uv connession expous:unse Engineering Vice President

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j nth Sji ined before me on this y day of A e J---

,1997 by Udew L WW otaFy Public Attachments cc:

A.B. ' Beach Regional Administrator-RIII G.F. Dick, Byron /Braidwood Project Manager - NRR S.D Burgess, Senior Resident Inspector - Byron C. Phillips, Senior Resident Inspector - Braidwood Oflice of Nuclear Facility Safety - IDNS L:nta bybwd usq &w::2

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ATTACIIMENT A l

DESCRIPTION AND SAFETY ANALYSIS FOR PROPOSED CHANGES TO THE BYRON /BRAIDWOOD UFSAR A.

DESCRIPTION OF PROPOSED CHANGES Comed proposes to change realistic dose values for the process gas system rupture in Section 15.0 of the Byron /Braidwood (B/B) Updated Final Safety Analysis Report (UFSAR). During preparation of a UFSAR change package, it was discoveied that the Final Safety Analysis Report (FS AR) had not been updated to correct an error from the previous revision of the dose calculation. Since the correct dose value is greater than that previously reported, the l

consequences of the accident had increased, and an unreviewed safety question resulted. The l

proposed changes are described in detail below. The marked up UFSAR pages are provided l

in Attachment B.

B.

DESCRIPTION AND BASIS OF THE CURRENT REQUIREMENT l

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The UFSAR includes specific dose values for each postulated accident in Table 15.0-11 for l

Byron and Table 15.0-12 for Braidwood. For the process gas system rupture, the realistic l

whole body dose is 6.52E-03 rem at the exclusion area boundary (EAB) and 1.50E-04 rem at l

the low population zone (LPZ) at Byron. For Braidwood, these values are 7.11E-03 rem at the EAB and 6.62E-04 rem at the LPZ. These values were determined in calculation B5-GW-01, Revision 0, which was approved on January 26,1978 and included in the FSAR.

The values were carried over into the UFSAR and have not been changed.

The methodology for the calculation is detailed in FSAR/UFSAR Appendix 15A, " Dose Models Used to Evaluate the Environmental Consequences of Accidents." The methodology is identical to that of Regulatory Guide 1.4, " Assumptions Used for Evaluating the Potential Radiological Consequences of a Loss of Coolant Accident for the Pressurized Water Reactor," Revision 2. The radiological source tt rms for the calculation are those provided in l

FSAR/UFSAR Table 15.7-2. These values were combined with atmospheric dispersion factors (X Qi and nuclear data in the calculation to determine the offsite doses at the EAB and

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LPZ.

C.

NEED FOR REVISION A note in a later resision of the calculation indicated that realistic dose values should be changed in the FSAR because of assumptions used in the calculation. However, the FSAR changes were not made, and the UFSAR continues to use values from an earlier revision of the dose calculation. A UFSAR change is required to reflect the current calculation.

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. In accordance with the provisions in 10 CFR 50.59(a)(2)(iii), this change requires NRC staff j

review and approval per the povisions of 10 CFR 50.90 because the consequences of an accident previously evaluated in the safety analysis result are increased.

l D.

DESCRIPTION AND BASES OF CilANGES TO B/B UFSAR l

Comed proposes to revise UFSAR Table 15.0-11 for Byron and Table 15.0-12 for l

Braidwood for the process gas system rupture realistic whole body dose. For Byron, the dose at the EAB is increased from 6.52E-03 rem to 6.53E-03 rem, and the dose at the LPZ is increased from 1.50E-04 rem to 1.51E-04 rem. Fer Braidwood, the dose at the EAB is increased from 7.1lE-03 rem to 7.14E-03 rem, and the dose at the LPZ is increased from 6.62E-04 rem to 6.63E-04 rem. These values were c'etermined in calculation B5-GW-01, Revision 2, which was approved on August 30,1984.

In Revision 2 of the calculation, the preparer noted that the curies released of Xe-131m was set at 0.0 in the original calculation, when Table i5.7-2, Source Terms, had a values of 2.79E+01 curies (realistic) and 4.69E+02 curies (conservative). The calculation was revised to include the contribution for Xe-131m. All other source terms remained the same, and the same methodology was used.

As a result of using nonzero values, the doses increased slightly over those that had been reported in the FSAR and those that are in the UFSAR. It is unknown why the original I

calculation used zero values for Xe-131m, or what prompted the calculation revision. There is no impact on the actual source terms or on any of the events of the waste gas decay tank rupture event.

E.

IMPACT OF Tile PROPOSED CIIANGES The change has no impact on the waste gas decay tank rupture accident as presented in UFSAR Subsection 15.7.1. The resulting dose increases slightly, since nonzero values for Xe-131m were used in the revised calculation. However, the values continue to be less than a small fraction of the 10 CFR 100 limits, i.e.,10 percent or 2.5 rem for whole-body dose.

They are also less than the dose limit of 0.5 rem to an individual at the nearest exclusion area boundary as established in Standard Review Plan 11.3, Branch Technical Position ETSB 11-5,

" Postulated Radioactive Releases Due to a Waste Gas System Leak or Failure," in NUREG-0800.

F.

SCIIEDULE REQUIREMENTS Comed requests approval in a timely manner so that the UFS AR may be revised to reflect the current dose calculation.