ML17300B246
| ML17300B246 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 01/03/1990 |
| From: | Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 161-02738-WFC-R, 161-2738-WFC-R, NUDOCS 9001110119 | |
| Download: ML17300B246 (9) | |
Text
ACCELERATED DISTjuBUTION DEMONS'.TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9001110119 DOC.DATE: 90/01/03 NOTARIZED: YES DOCKET FACIL:STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi 05000529 AUTH.NAME AUTHOR AFFILIATION CONWAY,W.F.
Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
R
SUBJECT:
Submits addi info re emergency Tech Spec Amend Request Section 4.1.3.1.2.
DISTRIBUTION CODE:
A001D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: OR Submittal:
General Distribution NOTES:Standardized plant.
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Arizona Public Service Company P.O. BOX 53999
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PHOENIX. ARIZONA85072<999 WILLIAMF. CONWAY EXECUTIVEVICEPRESIDENT NUCLEAR 161-02738-WFC/RAB January 3,
1990 Docket No.
STN 50-529 Document Control Desk U.
S. Nuclear Regulatory Commission Mail Station Pl-37 Washington, D.
C.
20555
Reference:
Letter from W. F.
- Conway, APS, to
- USNRC, 161-02727, dated December 29, 1989.
Subject:
Emergency Technical Specification Amendment Request, Section 4.1.3.1.2
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Unit 2 Emergency Technical Specification Amendment Request, Section 4.1.3.1.2, Additional Information File:
90-F-005-419.05; 90-056-026 During a telephone conversation between Mr.
G.
W. Knighton and members of the NRC Staff with Messrs.
Jack N. Bailey and J.
M. Levine of APS on January 2, 1990, several questions arose concerning the referenced letter.
The following discussion provides the additional detail requested.
The referenced letter stated that there would be significant schedule and economic impact if the amendment were not granted by January 9, 1990.
There are two factors which justify this statement.
The first is replacement power cost for two shutdowns required to perform surveillance testing if the amendment were not granted.
Each shutdown would take at least two days to complete, assuming that there were no unforeseen problems.
Two days for each startup 'are required since Unit 2 is at the end of core life and Xenon transients combined with Axial Shape concerns require a lengthy return to power procedure.
Replacement power
- costs, at this time of year, for PVNGS are approximately
$500,000 per day.
The second factor which must be considered is the effect on fuel Cycle 3.
The currently analyzed window for refueling of Unit 2 opens at 394 EFPD. If Unit 2 were to operate at 100% power continuously until February 23, 1990, the current date for shutdown to refuel the unit, 395 EFPD of burnup will have occurred on the current core.
Re-analysis to update the Reload Analysis Report would cost from $250,000 to $500,000.
Additionally, each additional EFPD not used on this core would incur
$100,000, of non utilized fuel costs.
If we assume that both surveillance shutdowns could be completed in the shortest amount of time possible, an expenditure of nearly
$3,000,000 would be incurred.
9001110119F00103 PDR ADOCK 05000529 P
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Document Control Desk U.
S. Nuclear Regulatory Commission Page 2
161-02738-WFC/RAB Ja'nuary 3,
1990 During the phone call the staff also requested the basis for the statement found on page 5 of the attachment to the referenced letter under "Stuck CEA(s)" which states "..
~ an analysis of the shutdown capability of Unit 2 with CEAs 27 and 41 stuck shows that there is sufficient scram reactivity to ensure subcriticality if no significant change in core temperature occurs."
Attachment A to this letter is a calculation which indicates the shutdown margin if the worst pair of CEAs were stuck on a reactor trip.
Since CEAs 27 and 41 represent a
configuration which has less stuck rod worth than the worst case pair, the worst case pair conservatively demonstrate the adequacy of the existing shutdown margin.
If an Atmospheric Dump Valve (ADV) were to stick open, coincident with a reactor trip in which the worst CEA pair were to stick, return to criticality would occur in 28 minutes.
This is based on the shutdown margin calculation in Attachment A, return to criticality temperature of 230 F.,
and a cooldown rate of 12 F./min.
If this event were to occur, it would be terminated by closing the affected ADV.
Closure of the valve can be accomplished by an operator in 10 minutes after reaching the valve. It is conservative to assume that the operator could reach the valve in 10 minutes.
Unit 2 operators will be instructed about the importance of promptly executing orders to close ADVs should this type of event occur.
As stated in the referenced letter the Reactor Operator would immediately initiate emergency boration in the event any CEA is not fully inserted following a reactor trip.
This boration would eventually return the required shutdown margin.
Therefore it can be seen that the cooldown can be terminated prior to return to criticality for this event.
Please note that Attachment H to the referenced letter provides an analysis which indicates the probability of a reactor trip complicated by two stuck CEAs and a large cooldown is very low.
APS has reviewed the Technical Specifications and found'hat no other changes should be requested at this time.
However, if one other CEA should become inoperable while the grounded coils exist on CEAs 27 and 41,APS,will follow the actions of Technical Specification 3.0.3.
If you should have any further questions, please call Mr. R. A. Bernier at (602) 340-4295.
WFC/RAB/jle cc:
G.
W. Knighton T. L. Chan M. J.
Davis J.
B. Martin T. J. Polich C.
F ~ Tedford
STATE OF ARIZONA
)
) ss.
COUNTY OF MARICOPA
)
I, W.
F.
- Conway, represent that I am Execu"ive Vice President Nuclear, that the foregoing document has been signed by me on behalf of Arizona Public Service Company with full authority to do so, that I have read such document and know its contents, and that to the best of my knowledge and belief, the statements made therein are true and correct.
W. F.
Conway Sworn To Before Me This Day Of 1990.
Notary Public My Commission Expires IBy Commission Bpire". hp~il 6, 199 l
gV E
t
ATTACHMENT A The information provided below indicates that without a change in temperature, there is more than enough scram reactivity worth to ensure subcriticality with two stuck Control Element Assemblies (CEAs).
Total Inserted Rod Worth Q 565 F,
-14.997 Worst Pair Stuck Rod Worth Q 565 F,
0 PPM Boron 6 934 Net Reactivity Difference With Two Stuck CEAs 8.063 Power Defect vs.
Power Level (EOC)
(100---0%)
Net Reactivity Balance
+ 2 415 5.648