ML19210A446
| ML19210A446 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/01/1970 |
| From: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| To: | John Miller METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 7910300452 | |
| Download: ML19210A446 (5) | |
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s; : ion - I'ni: 1,,,aich was suomi::ed on March 2,1970, con:ains cn an.lycis of the consequencas of majer piping f ailures in :he primary coolzn: sys:an. Tha; analysis uses a computar ccda, which is called a :cdified version of FLASH-I, in the compu:ation of thermal-hydraulic phencrena during e_ewdown of tha primary coolant. As we have dis-cussed with ycur representatives, the results of recent anclyses cf ECCS parformance using a culti-node computer code have rcise' tavarcl quasticns regcrding the charmcl-hydraulic response of the core during pos:ulated loss-of-coolant accident. We have concluded thct a more 1
da:cilad cna.fsis of :ae blowdcun phen ena using suitable multi-node
- achniques is needed for our evaluccion of your application. We are enclosic.; a raquas for addi icnal information which will provide guidance en tha secpe cnd detail raquired.
A1: hough sc a cf tha infor:ccion requas:ed =cy be available in the public racord in the e - ::.:x of our review of another facility, it wcule. Se c.alpful in :: is ins:cnca if ' our reply could be cde as f
cc pic:e cnd self-suf ficiant as possib1_. If your response to the cn.los.ca ;c..:s :ha for cf a tcpical raport which contains icforma-r considerad propristcry by you or your vendors, please pros'de a e
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Division of Racc or Licensing Enc 1:su c:
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.'otropolitcn Edison Cocipany 2
October 1,1970 cc:
Geor;;e . Trowbridge, Esq.
Shaw, Pittman, Potts. Trowbridge, Mdden, and Stuart Suite 1017 Barr Building 910 17th Street, !!.W.
Washington, D.C.
20006 Distribution:
Docket File AEC PDR DR Reading DRL Reading PWR-2 Reading C. K. Beck M. M. Mann F. Schroeder R. S. Boyd R. C. DeYoung D. Skovholt T. R. Wilson E. G. Case R. R. Maccary R. W. Klecker DRS Branch Chiefs DRL Branch Chiefs F. W. Karas (2)
D. F. Ross (3)
Attorney, OGC S. Hanauer 1487 034 PWR-?/DRL PWR-2/DRL PWRs/DRL DR DRL omcE >
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G L l..L.I.0-Form AEC-318 tRev. 9-531 AECM 0240 e a sovaneeser reiones orrics i,se o-a,e-ei,
Octoier 1, 1970 ADDITIONAL INFORMATION REQUESTED FOR THkEE MILE ISLAND UNIT 1 14.1.
Provide an evaluation of the Loss-of-Coolant Accident which makes use of a culti-node computer code for the description of the core and primary cool-ant system. This evaluation should include the following:
a.
A description of the models and equations that were used, and the bases for their selection.
b.
The empirical correlations assumed, the experimental bases for them, their ranges of applicability, and the ranges for which these corre-lations were used in the analyses. Specify the methods used to permit transitions between two empirical correlations for heat trans-
- fer, c.
A description of those other codes, such as a core thermal response code, used in the calculation and an indication of how the codes are coupled in the calculation.
d.
An estimate of the uncertainty involved in the calculation of peak clad temperature. This estimate preferably will be in the form of a probabilistic assessment of the likelihood of exceeding the calculated range of clad temperatures, e.
A summary of any experimental results which provide verification of your multi-node code.
14.2.
Provide the results of the analyses for a spectrum of breaks it; ;na inlet and outlet piping, including the following details:
a.
Core average and hot-channel flow rates vs time; if there are several core flow paths, provide the flow rate in each.
b.
Flow rate at the flow paths immediately above and below the core.
c.
Core pressure drop vs time, and system pressure vs time.
d.
Flow rates in the outlet piping, brdeen and unbroken loops, and in the inlet piping, broken and unbroken loops.
e.
lieat transfer coef ficient vs time at the hot-spot in the core.
f.
Peak clad temperature vs time.
1487 035
2 g.
A discussion of the importance of variations in assumed phenomena in the core or primary coolant system on the peak clad temperature. For example, if the continued performance of one or more primary coolant pumps is a key factor in the limiting of peak clad temperature, then the effect of variations in pump performance,on peak clad temperature should be investigated.
14.3.
Discuss the margin available in the ECCS design in terms of-a.
Selection of the design criterion for peak clad temperature, b.
Conservatism in heat transfer correlations.
c.
Conservatism in treating core flow rates.
d.
Conservacism in the treatment of the primary coolant pump performance.
e.
Conservatism in the heat transfer assumed during the portion of the blowdown where the core flow rate oscillates a'cout zero. Consider the likelihood and consequences of other than fully-developed flow during the oscillatory period.
f.
Conservatism in the choice of other parameters, including steam gener-ator performance, bubble rise model, two-phase friction multipliers, fuel-clad gap rssi stance, and physical properties of UO '2 d.
Conservatism in the use of heat transfer correlations derived from steady-state data in the prediction of transient heat transfer coef-ficients.
h.
Conservatism in the method of selecting the nodes for the core and primary system.
14.4 Provide an analysis for core performance in what is generally referred to as the reflooding stage to demonstrate that:
a.
The reflouding rate is sufficient, assuming that caly one chain (of two) of tha ECCS pumps is available. Consider the results of recently-developed experimental information from the FLECHT program in your response.
b.
The pressure drop caused by the ef fluent two-phase nixture does not excessively retard the reflooding.
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5.
Provide a summary of the number of fuel roda that will reach or exceed a given clad temperature as a function of clad temperaturc.
1487 OL36
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- 3 14.6.
Discuss the applicability of the assumption that flow from the loops to the vessel is distributed uniformly across the fuel assemblies.
14.7.
What additional analysis or experimentation do you plan relevant to the prediction of events following a postulated piping failure?
14.8.
Describe the effect of the positive mcderator coef ficient on the calculated peak clad temperature.
1487 037