ML19276H362
| ML19276H362 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/21/1974 |
| From: | Bernero R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7910160698 | |
| Download: ML19276H362 (4) | |
Text
d NM 21 ic74 DOCT : 0. : 50-289 APPLICM;T : METROPOLITKT EDISO:i C0"PN.T FACILITY :
TlR".E MILE ISLAND, C IT 1 REPORT OF }CETI3G O'I FE3EUARY 1, Q974 AT BET'dESDA, l'ARTLMID SUM! ART The meeting was held to discuss the design basis of the Three Mile Island, Unit 1 (TMI-1) Emergency 7eedwater System (EWS). The sizing paraneters and various analyses were discussed, including High Pressure Injection (EPI) Cooldown. No comm:itments were made at this meeting. The attendance list is attached.
DISCURSION The meeting opened with a general discussion of the background of the inquiry into the EWS. It was noted that this is part of a more general review of EWS designs in older plants; THI-l was selected as a sat:ple plant because of its basic EWS design and the fact that its Final Safety Analysis Report (FSAR) reported analysis of the HPI Cooldown technique as an alternative to the EWS.
Various spokesmen for the applicant explained the EWS and system analyses and answered AEC staff questions.
A.
EWS Desir;n For plants of this vintage, the design of the EWS was the responsibility of the architect-engineer.
In this case, BW recoer. ended that the size of the EW pu=ps be 720 gpm for the rermval of decay heat and 920 gp= if the applicant wanted a 1000F/hr cooldown as well. The applicant chose one turbine-driven 920 gpu pt::np and two 460 gpm =otor-driven backup pumps.
The TMI-1 EWS is started automatically, but the applicant's analysis indicates that there is adequate time to start the system manually.
Assuming initial Reactor Coolant System conditions of 5800F and 2200 psig, a mass energy balance shows that the system vill c pand to lift the pressurizer relief valves (code safetics) in about 5 minutes; the pressurizer goes solid in another 10 minutes. All the principal components of the TII-1 EWS can be operated from the EW control panel in the 1420 046 9910160bI
!'.cct;ing Surrary 2-pra 21 1974 Control Rocn.
E.
L'?I Cooldeve The HPI Cooldown analysis was done with the CRAPI ccde. The C0!;TDTT code was used for reactor building calculatiens.
To start, it was assumed that one stean line ruptured and the plant was tripped by the Reactor Protection System with a cencurrent loss of offaite power. The chronology of events, taken from the FSAR and attached here, was aed to proceed with the discussian.
The analysis assumed that the operator started one HPI pump after 15 minutes. The flow delivered by this one pump at the system relief valve setting was calculated as being in the range of 225-240 gpm. The relief valve flow c:odel used was based on variable area because the CEAFI code needs a flow area to work with.
The codel und zero area at 2475 psig and at 2500 psig it used critical flow area for the valve manufacturer's design liquid flow rate.
Ir this model, the relicf valve is capable of passing about 70% core flow than the pump output. Consequently, the peak system pressure stays at nbout 2480 psig.
Af ter 4500 seconds (75 minutes), the EPI pu=p flow rate matches the decay heat rate, assuming 100% vaporization. After 15,000 seconds (250 minutes),
the flow matches the decay heat without boiling. The Borated Water Storage Tani is depleted after 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> with the Reactor Coolant System still at about 5000F. At that time, recirculation flow would be started by drawing water from the Reactor Building sump using a Low Pressure Injection pump as a booster to deliver it to the auction of the HPI pump.
Origina.* Signed R.11. Ecrnero, Project Manacor Light Water Reactors 3 ranch 2-3 Directorate of Licensing
Enclosures:
1.
Attendance List 2.
Chronology of Events for HPI Cooldown
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A MAR 21 1874 ATTENDANCE LIST THREE MILE ISLAND 1 DOCKET NO. 50-289 FEBRUARY 1, 1974 Atomic Energy Comission Gilbert Associates Inc.
R. M. Bernero W. F. Sailer
- 3. C. Buckley V. H. Willens D. K Davis S. Hunt V. A. Moore R. W. Klecker I. A. Peltier D. Eisenhut T. Novak K. Kraynick L..Derderian S. Salah Babcock & Wilcox W. A.
Cobb C. Russell E. G. Ward G. F. Glei E. J. Butcher D. W. LaBelle B. E. Miller A. McBride Florida Power Corporation B. DuBois GPU Service Corporation R. Burns J. Vann J. P. Moore 1420 048
O MAR 2 1 574 CHRONOLOGY OF EVENTS FOR HPI C00LDOWN AFTER A STEAM LINE BREAK Time (seconds)
Event 0
Double-ended break of a 24 inch diameter steam line on the secondary side 9
1 Reactor trip on variable low pressure; turbine stop valves close isolating the unaffected steam generator 47 Damaged steam generator blows dry 450 Unaffected steam generator provides no more heat sink; minimum system pressure of about
.350 psia is reached 900 Operator action starts one HPI pump 1200 Primary loop becomes solid with subcooled water; pressurizer code relief valve opens at setpoint of 2515 psia 2300 Reactor building cooler actuation setpoint of 4 psig is reached 5700 Steam first appears in the core 8500 Minimum coolant level in reactor vessel is reached; core remains covered 8800 containment building pressure reaches the maximum value of 24 psig 1., h 2. )