ML17054C013

Forwards Draft SSER-2 Section 15.6.5, Radiological Consequences of Locas, in Response to D Hill Request.Encl Draft Accepts Proposed Tech Spec Bypass Leakage Limits in FSAR Table 6.2-55.SSER-2 Will Be Issued Later in Month

ML17054C013
Person / Time
Site:	Nine Mile Point
Issue date:	11/05/1985
From:	Novak T Office of Nuclear Reactor Regulation
To:	Hooten B NIAGARA MOHAWK POWER CORP.
References
NUDOCS 8511200099
Download: ML17054C013 (14)

Text

Docket No.:

50-410 NOV 5 1985 Mr. B. G. Hooten Executive Director of Nuclear Operations Niagara Mohawk Power Corporation 300 Erie Boulevard West

Syracuse, New York 13202

Dear Mr. Hooten:

DISTRIBUTION

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SUBJECT:

DRAFT SER SECTION 15.6.5 ON SECONDARY CONTAINMENT BYPASS LEAKAGE Enclosed for your information is a draft of Section 15.6.5 "Radiological Consequences of Loss-of-Coolant Accidents" from Safety Evaluation Report Supplement 2 (SSER-2).

SSER-2 is expected to be issued later this month.

A draft of Section 15.6.5 of SSER-2 is being provided in advance in response to a request from Mr. Donald Hill of your staff.

Any question concerning the enclosed should be directed to the Licensing Project Manager Mary Haughey (301) 492-7897.

Enclosure:

As stated cc:

See next page Thomas M. Novak, Assistant Director for Licensing Division of Licensing pA'B82/

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Docket No.:

50-410 NOV 5 )ASS Mr. B. G. Hooten Executive Director of Nuclear Operations Niagara Mohawk Power Corporation 300 Erie Boulevard West

Syracuse, New York 13202 DISTRIBUTION DDD BG i NRC PDR JPartlow Local PDR EJordan NSIC JRead PRC System LB¹2 Reading EHylton MHaughey OELD, Attorney ACRS (16)

SUBJECT:

DRAFT SER SECTION 15.6.5 ON SECONDARY CONTAINMENT BYPASS LEAKAGE Enclosed for your information is a draft of Section 15.6.5 "Radiological Consequences of Loss-of-Coolant Accidents" from Safety Evaluation Report Supplement 2 (SSER-2).

SSER-2 is expected to be issued later this month.

A draft of Section 15.6.5 of SSER-2 is being provided in advance in response to a request from Mr. Donald Hill of your staff.

Any question concerning the enclosed should be directed to the Licensing Project Manager Mary Haughey (301) 492-7897.

Enclosure:

As stated cc:

See next page Thomas M. Novak, Assistant Director for Licensing Division of Licensing Ll(82/

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~UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 Docket No.:

50-410 Iir,,

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Nr. B. G. Hooten Executive Director of Nuclear Operations Niagara Nohawk Power Corporation 300 Erie Boulevard West

Syracuse, New York 13202

SUBJECT:

DRAFT SER SECTION 15.6.5 ON SECONDARY CONTAINNENT BYPASS LEAKAGE Enclosed for your information is a draft of Section 15.6.5 "Radiological Consequences of Loss-of-Coolant Accidents" from Safety Evaluation Report Supplement 2 (SSER-2).

SSER-2 is expected to be issued later this month.

A draft of Section 15.6.5 of SSER-2 is being provided in advance in response to a request from Nr. Donald Hill of your staff.

Any question concerning the enclosed should be directed to the Licensing Project Nanager Nary Haughey (301) 492-7897.

Enclosure:

As stated Thomas N. Novak, Assistant Director for Licensing Division of L'icensing cc:

See next page

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Mr. B. G. Hooten Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station Unit 2 CC:

Mr. Troy B. Conner, Jr.,

Esq.

Conner 8 Wetterhahn Suite 1050 1747 Pennsylvania

Avenue, N.W.

Washington, D.C.

20006 Richard Goldsmith Syracuse University College of Law E. I. White Hall Campus

Syracuse, New York 12223 Ezra I. Bialik Assistant Attorney General Environmental Protection Bureau New York State Department of Law 2 World Trade Center New York, Hew York 10047 Resident Inspector Nine Mile Point Nuclear Power Station P. 0.

Box 99

Lycoming, New York 13093 Yr. John W. Keib, Esq.

Niagara Mohawk Power Corporation 300 Erie Boulevard West

Syracuse, New York 13202 Mr. James Linville U. S. Nuclear Regulatory Commission Region I

631 Park Avenue King of Prussia, Pennsylvania 19406 Norman Rademacher, Licensing Niagara Mohawk Power Corporation 300 Erie Boulevard West

Syracuse, New York 13202 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania 19406 Mr. Paul D. Eddy New York State Public Service Commission Nine Mile Point Nuclear Station-Unit II Post Office Box 63

Lycoming, New York 13093

0

15 ACCIDENT ANALYSIS 15.6 Decrease in Reactor Coolant Inventor 15.6.5 Radiological Consequences of Loss-of-Coolant Accidents In Tables 6.2-55a and b of FSAR Amendment 21, the applicant identified 20 poten-tial paths by which containment leakage could bypass the secondary containment.

In FSAR Table 15.6-13, the applicant also identified the traversing incore probe line as an additional source of leakage from the drywell into the secondary containment.

The staff has further evaluated the plant stack, and has concluded that this structure is in compliance with Regulatory Guide 1.3, "AssumptionsTo Be Used for Evaluating the Potential Radiological Consequences of a Loss of Coolant Accident at Boiling Water Reactors,"

Positions C. l.e and C.2.a.

The dose conse-quences from containment leakage and engineered safety feature leakage following a loss-of-coolant accident (LOCA), therefore, have been recomputed assuming that the standby gas treatment system discharges to the environment through the plant stack, rather than to the environment at ground level.

In this recomputa-tion, containment leakage was assumed to be at a rate of 1.31K per day in order to include the additional leakage through the traversing incore probe penetra-tion.

Because of the increased atmospheric dilution afforded by release through the 131-meter-high plant stack; computed radiological consequences are reduced from those reported in the SER despite the increased containment leakage assumed.

The radiological consequences of the postulated LOCA due to containment and engineered safety features (ESF) leakages were evaluated in accordance with Standard Review Plan (SRP) Section 15.6.5, Appendices A and B, respectively.

Leakage through the 20 bypass pipelines,

however, could not be evaluated by direct application of any single SRP section.

The applicant submitted two analyses of flows through the bypass leak paths, corresponding to isothermal and adiabatic gas expansions, respectively.

Both analyses accounted, for slow depressurization of the containment because of leak-

age, and the cooling of the pipes carrying the bypass flow.

The depletion of molecular and particulate iodine fission products was modeled using deposition rate equations developed by an NRC contractor (NUREG/CR-2713).

Both analyses concluded that virtually no molecular or particulate iodine would survive pas-sage through the bypass leakage

paths, and that radiodine could escape to the environment principally as organic vapor (iodomethane),

and only after consid-erable delay in transiting the bypass pathways.

Following applicable portions of SRP Sections 6.5.3 and 15,.6.5, Appendices A

and 0, wherever possible, the staff performed an independent analysis.

The SRP suggests that the staff assume that bypass leakage occurs at the proposed Tech-nical Specification limit for each valve.

Such an assumption is conservative, but prevents any physically consistent treatment of-flow variation with temper-ature.

The staff, therefore, assumed constant laminar flow at the Technical Specification limiting rate.

This assumption is a deviation from the SRP and more realistically models the release that would occur in such an accident.

NMP-2 SSER 2

15-1

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All available information indicated that particulate matter and molecular iodine would be expected to deposit on surfaces, with rates of deposition varying with temperature,

pressure, gas composition, surface material, and particulate size.

Since these parameters cannot be predicted reliably, the staff assumed simple first-order depletion at a constant rate of 10X per hour.

Organic iodine was assumed to pass without depletion.

Bypass leakage was assumed to enter the environment at ground level.

The estimated total LOCA doses are listed in Table 15. 1, and are less than the guideline values of 10 CFR 100.

The staff concludes that the applicant's pro-posed Technical Specification bypass leakage limits, as presented in FSAR Table 6.2-55, are acceptable.

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Table 15. 1 Radiological consequences of a loss-of-coolant accident Leakage path Bypass leakage Containment leakage ESF leakage 40.

0.4 4.

0 1 Exclusion area boundary 0-2-hr dose, rem Thyroid Whole body 10 0.1 Low population zone 0-30-day dose, rem Thyroid Whole body 240

1. I 15 0.8 Total 55.

265.

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