ML19224C660
| ML19224C660 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/14/1979 |
| From: | Chirasanta K THAILAND, GOVT. OF |
| To: | Mattson R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19224C659 | List: |
| References | |
| NUDOCS 7907060026 | |
| Download: ML19224C660 (3) | |
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11t May 1979 Roger J.1:at toon Director, Div. o f Systcm Safety US:!iRC i.'a chingto n D.C.
20555
Dear Sir,
It acem only yecterday I as sitting in the class listening to your lecture in SAR at Arconne during Fall 1972.
But do you renlined it has been eight manths ? Time so so fast.
Two days after SAR cource I had a chance to attend (A cource v:hich alco in Argonne and cet with Dr. ililbur Moz ricon o f US.NRC.
He cane to Banckok to attend QA seninar so I had a chance to chon him around.
I hope this letter will find you in good health and v: ell but very busy cince 3-Mile-Ialand accident.
I am nou v:orking as a deputy chief for the project on the Organization of Nuclear Regulatory Activity in dealing <ith tPa N.P.P.
Since the Three mile Icland unit 2 accident on 23/3/79 at It AM.
There :ere many contradic tory reports from various cources.
I have been left in the shadou o f doub t.
I hope that I might cet some reliable informatione from you if they are not confidential.
I saw T.V. Sattelite news-reel on March 29 chowed the picture of break at the Steam line before entering turbine :hich were bla.c for the cauac o f the accident.
From few Telex our o f fice received from IAEA which I can conclude the cause of failure during the plant operate at 100 % power.
1.
Reduction of Feed in SG and Turbine Trip.
2.
Precoure in RCS increase and Reactor Trip.
3 Precourizer relief valve open but did not reclose properly.
f.
Rupture disc, ruptured and discharged into containcent.
t 5
All safe ty System func tion properly.
From IAEA p2cvious telex m:ntions o f RCS level drop 2 f t. belov, core top damaging.5-1 FCf o f fuel.
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7907060620 If the abovo coquence is trued it renind r-e the Deprencurination o f RCS at Davic Becco Unit 1 on September 24,1977 the UFP is B &W 177FA.
I think it is the care type as Three cile Island.
The trancient started shen a cpurious half-trip occurred in SFRCS resulting loca o f flow in SG // 2 and cause full SFR03 trip, closing MSIV.
Pressure and temperature riced due to locc of heat cink.
Procsurizer relief valve open but fail to cloce.
The operator observed precourizer level riced and nanual chut down reactor 12 min. after trnnsient end learn that the relief valve did not close 21 nin.
a"ter transient and RCS Preauure drop to 075 psi.
Davic Bocco Unit 1 operate at 9 3 ?! power at that time and no cara damage in that event.
I underctand that the depreccurization due to the relief valve o f the Preccurizer stay open it acom like the cmall LOCA at Hot leg.
The blow out rate of R through relief valve is far leccer than 025 lb/s.
The LPI can certainly nahe up the RC to cope with loas o f coolant and steam Generated in RCS.
I think that the core will have no trecble to naintain coolable geo-cetry and can maintain longterm cooling with-out any probloca.
But from chat I read in the newcweek ca; azine quo ted c; hat you had said during the accident.
"No Plant has even been in this condition" "He can failure modes the like o f which has never been analyced" It also mention Mr.
V. Gilinsky talking about the Hydrogen bubble in reactor - a ceriouc problec that no one had foreceen.
It make ce feel that the accident nicht had core serious effects and concequences than what had been postulated in DBA.
So you had real hard tice in naintaining the longterm cooling for the core af ter the accident.
Does this accident prove come con-cervatica in the SAR or in the computer code using in the analysis of the EOCS.
?
Meny B & J NSS have been ordered to chut down for inspec tion and codi-fication by US.NRC.
I renember from the lecture of Mr. Novak and Thadani on AT"lS. the B & W has the cmallest capacity of precsurizer relief valve.
Does the NRC order for c.odification to ful fill the ATJS requirement by URC 7 Af ter 3 MILE ISLAND accident I have to bring out nany lecture caterials from SAR cource, such as of Mr. Fabic, Mr. Rar.ond School, Mr. To m Nov ak, Mr. A. Thadany and Mr. Gordon L. Chipman, to study more care fully.
I will be very happy to hear from you when you have time.
1.
What is the actual failure codes ?
2.
Are the amount of Hydrogen Generation nuch more than postulated in the accident analysis and caurce a lot o f trouble than expected for maintaining longterm core cooling after accident ?
3 Why rater vere few inches in Aux Bldg's floor ?
Did it come out through failure of pump cen1 in Aux Bldg ?
4.
How long it take you to obtain longterm core cooling after the accidents.
q,r n f, O cCJ U4V
3-a I hope that you and your f a:ailj "ro all happy anl Bect veiches froa your student from other side of the v;orld.
Sincerely,
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( lir. Krisadang Clirasanta) 265 049