ML19209A597

Comments on Reactor Coolant Sys Conditions in Conjunction W/Steam Generator Secondary Blowdown.Nrc Should Be Requested to Present ECCS Analysis Which Will Form Basis for Emergency Instructions

ML19209A597
Person / Time
Issue date:	06/28/1979
From:	Michelson C Advisory Committee on Reactor Safeguards
To:	Okrent D, Plesset M Advisory Committee on Reactor Safeguards
References
ACRS-CT-1140, NUDOCS 7910050041
Download: ML19209A597 (2)

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ADVlsORY COMMITTEE ON REACTOR SAFEGUARDS j

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JUN 2 8 G79 TO: Dr. Okrent, THI-2 Implications Subcommittee b //YD Dr. Plesset, ECCS Sobcomittee lD/2 9/a/11 From:

C. Michelson,

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ACRS Consultant

SUBJECT:

CONSIDERATION OF REACTOR COOLANT SYSTEM CONDITIONS IN CONJUNCTION WITH A STEAM GENERATOR SECONDARY SIDE BLOWDOWN A steam generator secondary side blowdown is a design basis event which is described, in part, as a steam line break in Chapter 15 of the plant FSAR.

For larger breaks, this event leads to rapid depressurization of the reactor coolant system due to fast cooldown. The resulting automatic initiation of the high pressure injection pumps will eventually lead to pressurizer refilling.

I believe this event needs to be looked at from the viewpoint of operator understunding and response, and other possible TMI implications. Of particular concern is operator response to the onset of a possible water-solid condition What on the primary side in conjunction with secondary side blowdown effects.

should the operator response be? Will time and attention span be availaM e?

What are the implications for decay haat removal by natural. convection if off-site power is lost following the turbine trip?

I109 077 Also of interest are a few "what if" type questions associated with the possi-bility of a consequential small LOCA. Such a LOCA might result from the primary This could system going water solid and lifting a relief and/or safety valve.

be followed by failure to reclose as a postulated single active component failure The probability hf Qp 0 50 d[

in conjunction with the secondary side blowdown.

JW yp h a_lified to operate with two-

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by the ; operator while he responds to the overriding consequences of a large secondary side break? What operator response will be required?

What are the implications for decay heat removal?

It should also be pointed out that a small LOCA can be caused by a large secondary side blowdown if pipe whip or jet impingement protection is not provided for all primary side piping. If the consequences of a concurrent small LOCA are not acceptable, it will be necessary to assure that such pipe break interactions do not exist.

Also of concern would be the integrity of steam generator tubing during a large secondary side blowdown. These tubes are not asstaned to fail in the present FSAR Chapter 15 analysis even though the mechanical loadings might be severe during the blowdown.

If the consequences of a concurrent small LOCA due to tube rupture are not acceptable, it will be necessary to provide commensurate assurance of tube integrity.

I believe it might be worth your time to discuss these items with the NRC staff.

The staff should be asked to present an ECCS analysis which can form a basis for appropriate emergency operating instructions for the secondary side blowdown case with various reactor coolant system conditions. These instructions should also be provided for ACRS review.

cc: ACRS Members H. Denton E. Case 1109 078 R. Mattson J. Conran W. Lipinski I. Catton