L-80-306, Forwards Updated Response Re Natural Circulation Cooldown. Emergency Operating Procedure 0120040 Revised to Address Recognition of Potential for Upper Head Steam Formation & Cooldown Rate Necessary to Prevent Void Formation
| ML17208B011 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 09/16/1980 |
| From: | Robert E. Uhrig FLORIDA POWER & LIGHT CO. |
| To: | Novak T Office of Nuclear Reactor Regulation |
| References | |
| L-80-306, NUDOCS 8009230306 | |
| Download: ML17208B011 (7) | |
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REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:8009230306 DOC ~ DATE: 80/09/16 NOTA D:
NO FACIL:50-335 St.
L'ucie Plant~
Unit li Florida Power 8 Light Co.,
AUTH ~ NAME AUTHOR AFFIl IATION UHRIGg R ~ E ~
Florida Powe.r 8 Light Co.
RECIP ~ NAME RECIP IENT AFFILIATION NOVAKpT ~ MD Assistant Directol for Operating Reactors DOCKE'T 0'5000335
SUBJECT:
Forwards updated response re natural circulation cooldown ~
Emer gency Oper at ing Procedure 01200<IO revi sed to addr ess recognition of potential for upper heed steam formation 8
cooldown rate necessary to prevent void formation.
DISTRIBUTION CODE:
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TITLE: General Distribution for after Issuance of Operating Lic NOTES INTERNAL: D/DIR HUM FAC08
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RECIPIENT ID CODE/NAME ACTION:
CLARKE R ~
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0 FLORIDA POWER 4 LIGHTCOMPANY September 16, 1980 L-80-306 Office of Nuclear Reactor Regulation Attention:
Mr.
Thomas M.
Novak Assistant Director for Operating Reactors Division of Licensing U.
S. Nuclear Regulatory Commission Washington, D.
C.
20555
Dear Mr. Novak:
Re:
St. Lucie Unit 1 Docket No. 50-335 Natural Circulation Cooldown This letter is an update of our letter (L-80-272) dated August 25, 1980, concerning the above subject.
We said in that letter that we would provide an update of our response to guestion 1, concerning the drain and fill method, and that we would provide a schedule for answering the remaining questions.
We anticipate receiving the additional engineering work on the drain and fill method from our NSSS vendor by early October, along with the answers to questions 2a and 2b.
We will review this information and submit our response by October 15, 1980.
The analysis required to fully answer guestion 3 will take about four months.
It is our intention to submit the results of this evaluation by February 1, 1981.
The answer to guestions 4 and 5 are attached.
Very truly yours, i,u. Q7 Robert E.
U rig Vice President Advanced Systems 8 Technology REU/PLP/cph cc:
Mr. J.
P. O'Reilly, Region II Harold F-Reis, Esquire 80092S 0 3og PEOPLE... SERVING PEOPLE
4 4
ATTACHMENT Re:
St. Lucie Unit 1
Docket No. 50-335 Natural Circulation Cooldown uestion 4 Res onse St. Lucie Plant Emergency Operating Procedure
- 0120040, "Loss of Reactor Coolant Pump Flow/Natural Circulation" has been revised (Revision 5) to address each of the below concerns.
1.
Reco nition of otential for u er head steam formation.
A discussion in Steps 5.3.2.3 (h) (3) and 5.3.2.3 (j) addresses the problem of uneven cooling in the reactor head area and alerts the operator to the potential for steam void formation.
2.
Cooldown rate necessar to kee from void formation.
The procedure states that a 25-.30'F/hour cooldown rate should be established and that the cooldown should be stopped at approximately 350' RCS temperature for four (4) hours.
This soak period will allow the reactor head temperature to catch up with RCS cooldown.
A cautionary note will be added to the procedure to ensure that a
sufficient water volume is available in the condensate storage tank.
3.
Reco nition of u er head steam formation.
The procedure lists the following as indications of RCS voiding:
a.
RCS temperature
> Tsat for the corresponding RCS pressure.
b.
Rapid increase in pressurizer level when charging through auxiliary sprays.
c.
Rapid decrease in pressurizer level when charging to RCS loops.
4.
Action to be taken in the event of u er head steam formation.
The procedure recommends considepation of the following alternatives:
a.
Reviewing and selecting one RCP in each loop for restarting.
b.
Elevation of RCS pressure by use of HPSI, LPSI, or use of pressurizer heaters.
Ca Stopping the cooldown and reduction of void size by sequentially spraying through auxiliary spy@ q and RCS loops with letdown secured and pressurizer heaters on.
uestion 5 Res onse The experience gained in the St. Lucie Unit 1 natural circulation cooldown event has been factored into the St. Lucie site operator training and requalification program.
However, since Florida Power 8 Light Company does not operate its own training simulator, we cannot respond directly to this question.
Since natural circulation cooldown is a generic issue, this question should be addressed to the owners of simulators used for operator training.
f V
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