ML19327A661

Discusses Differing Professional View Re Issuance of SER to Plant Allowing Full Power Operation W/Open 42 Containment Isolation Valves & Methodology Use for Calculating Related Offsite Doses

ML19327A661
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	05/11/1989
From:	Licciardo R Office of Nuclear Reactor Regulation
To:	Murley T Office of Nuclear Reactor Regulation
Shared Package
ML19327A642	List: ML19327A641 ML19327A643 ML19327A644 ML19327A647 ML19327A651 ML19327A652 ML19327A656 ML19327A657 ML19327A658 ML19327A660 ML19327A661 ML19327A662 ML19327A663 ML19327A664 ML19327A665 ML19327A666 ML19327A667 ML19327A668 ML19327A669 ML19327A670 ML19327A671 ML19327A672 ML19327A673 ML19327A693 ML19327B570 ML19327B588 ML19327B595 ML19327B596 ML19327B598 ML19327B599
References
TAC-73427, NUDOCS 8909140118
Download: ML19327A661 (2)

Text

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. MEMORANDUM FOR: Thomas E. Murley, Director-Office of Nuclear Reector Regulation Robert 8.A.Licciardo,ReactorEngineer(Nuclear)-

FROM:

Plant Systems Branch Division of Engineering and Systems Technology

SUBJECT:

DIFFERING PROFESSIONAL VIEW CONCERNING a) Issuance of SER to Zion 1/2 allowing full power operation with open 42" containment isolation valves.

b) Methodolog used for calculating related offsite doses.

ThewritersubmitsaDifferingProfessionalView(DPV)inaccordancewiththe provisions of NRC Manual Chapter 4125.

This issue has arisen out of the Safety Evaluation Report (SER) undertaken for i

the Zion Units 1 and 2 as prepared by the writer; see Attachment.

The principal issue is the prudent and conservative calculation of the additions to offsite dose which may result from a LOCA at'a facility during the use of L

open purge supply and exhaust valves at full power.

The licensee for Zion 1/2 has proposed full power operation of the facility with the 42" purge supply and exhaust containment isolation valves open to a limited position of 50', and capable of isolation within seven (7) seconds I-of the.coamencement of a LOCA.

The writers SER concludes.that the 42" valves at Zion should remain closed in Modes 1, 2 3 and 4 because the consequence of the offsite dose to thyroid (from fodine),during a LOCA is unacceptably hight whole body has not been The least value for the additional offsite dose which may be evaluated.

proposedwithinthelicensingbasisis64,000removerthefirstseven(7) seconds of the LOCA.. Management staff has. disagreed with the writer's methodology and conclusion and plans issuance of a separate SER permitting The writer requests non-issuance of the related SER the operation requested.

He also proposes probability of a generic action on other to the licensee.

facilities which have been granted such licenses based on the staff's current methodology.

In general, t'he management staff has adopted a criterion described in SRP h

STP CS8 6-4 which is that providing the maximum time for closure of these containment isolation valves does not exceed 5 seconds (and by plant-specific L

exception, up to 15 seconds), then the valves would be closed before the onset of fuel failure following a LOCA so that the only contribution to offsite dose is from RCS operational levels of fission product directly discharged into containment during this period, and then through the open containment isolation I

valves before closure.

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Thomas E. Murley 4 /*

In evaluating the consequence for Zion, the writer has used an alternate Criterion in BTP C58 6-4 which states that.

1 "The following analyses should be performed to justify the containment purge system design:

An analysis of the radiological consequences of a loss-of-coolant accident. The analysis should be done for a spectrum of break sizes, and the instrumentation and setpoints that will actuate the purge valves closed should be identified. The source term used in the radiological c.alculations should be based on a calculation under the terms of Appendix K to determine the extent of fuel failure and the concomitant release of fission products, and the fission product activity in the primary coolant. A pre-existing'todine spike should be considered in determining primary coolant activity. Tae volume of containment in which fission products are mixed siould be justified, and the fission products from the above. sources should be assumed to be released through the open purge valves during the maximum interval required for valve closure. The radiological consequences should be within 10 CFR Part 100 guideline values."

the fuel performance over the 0-7 seconds tising these related guidelines for Zion,(by infringement of DNBR criterw) is detailed and shows that fuel failure occurs within 6 seconds of the cosinencement of the LOCA, and together with other licensing basis responses including fission product release from the fuel gap and the thermal hydraulic conditions in the core, containment and discharre nozzle, result in a substantive discharge of fission products to the environeant of far greater consequence than are calculated by the staff.

The relative consequences of these differing approaches are that whereas the staff methodology gives additions to offsite dose resulting in total doses within 10 CFR Part 100 limits, the alternate approach used by the writer shows a substantially increased offsite dose exceeding 10 CFR Part 100 Timits, with completely unacceptable consequences to Public Health and Safety.

l The writer requests review of the Differing Professional View in a timely manner in accordance with the provisions of NRC Manual Chapter 4125.

f RAW Robert B. A. Licciardo Registered Professional Engineer California Nuclear Engineering License No. N') 001056 Mechanical Engineering License No. M 015380 cc:

J. Snieiek D. Muller S. Varga C. Patel F. Miraglia l

L. Shao L

A. Thadani L

J. Wermiel l

J. Kudrick l

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