ML20210L309
| ML20210L309 | |
| Person / Time | |
|---|---|
| Issue date: | 02/27/1986 |
| From: | Cafton I, Catton I Advisory Committee on Reactor Safeguards |
| To: | Igne E NRC |
| References | |
| FRN-51FR2612, REF-GTECI-A-49, REF-GTECI-RV, RTR-REGGD-01.XXX, RTR-REGGD-1.154, RTR-REGGD-1.XXX, TASK-A-49, TASK-OR, TASK-RE, TASK-SI-502-4 NUDOCS 8604290291 | |
| Download: ML20210L309 (2) | |
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DSOR Sj 00CHETED USNRC RULES & PROCEDURES 8R TO:
El Igne OROADM j )7/g f FROM:
Ivan Catton
SUBJECT:
Metal Components Subcommittee Meeting H street 16 AR? 28 A8 32 67[/ b2)f/,)
r 27 February 1986 i
At the subcommittee meeting I told you I had some comments on the PTS Draft Reg Guide. Although tardy, my comments follow. Actually i
I'm trying to clear the decks of promised reports before I go off to Holland to give a series of lectures.
The claim is made that " conservative assumptions
- make the results bounding (?) for any PWR.
If assumptions are made one must know what they are and be able to list them.
I can find no auch list. The only conservative ass;umption I can find is the l
i 60 deg F added to the RTNDT.
i The Reg Guide states that a number of calculations must be made
~
I if the calculated frequency of thru-wall cracks is greater than j
SE-06. I calculated 5E-05 for Oconee using numbers from staff sponsored research reports. What next? It seems to me that either the screening criterion needs adjustment or at a minimum some re-calculation is in order.
i The rule specifies an across the board RTNDT of 279 deg F
for j
axial and 388 deg F for circumferential welds. My review has led 1
se to believe that either the numbers are too large or there ought to be some plant specific cavents and some attention paid to what happens following a through the well crack.
j I don't understand all the "shoulds" in the first paragraph of chapter 1.
The chapter does describe en overall approach not
'should describe" This carrying the Reg Guide philosophy a bit too far. Chapter 2 describes briefly what is required to describe plant systems.
Saying it should do so is silly.
It l
either does or it doesn't.
I Under topics covering operator actions, I would think requiring something like the ORNL contribution to the SEP program would i
be very valuable. It was essentially en operating history of the I
plant with some conclusions about maintenance practices and operations.
i 6
I In the chapter discussing T/H calculation, the reader is referred to Calvert Cliffs and HB Robinson PTS calculations base on TRAC i
and RELAP5. Can the reader use the code that impacts least on him.
plant? Rectil that TRAC and RELAP5 will yield dramatically different vessel conditional failure probabilities.
l The section on T/H models (4.2) is too loose. For examples a)Dne doesn't discuss nodalization schemes, one uses standard i
i techniques to estimate errors.
i b)You don't easily estimate multi-dimensional behavior from one-1 dimensional calculations without fell scale experimental data.
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- c)There is no requirement for accurate prediction of condensation except in the pressurizer. We all know the codes do not handle condensatioon very well.
Will the applicant T/H modeling have to be better than that found in TRAC and RELAP57 Are there no requirements for code verification?
I have no comment on chsprter 5 and chapter 6 looks good.
The chapter on uncettainties (7) is week. There is no way a Monte Carlo analysis will help determine the uncertainty resulting from poor or physically incorrest modeling. I think one should limit the use of Monte Carlo methods to where they make sense.
This is the section where requiremenste for nodalization studies belongs.
Under corrective actions (chap 8),
I see no mention of pressure control, say by a " Reed system sever".
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