ML18127B151

FP&L Does Not Plan to Replace CEDM 44 During the Present Outage; FP&L Requests Section J Be Deleted from Enclosure 1 to Operating License

ML18127B151
Person / Time
Site:	Saint Lucie
Issue date:	10/07/1976
From:	Robert E. Uhrig Florida Power & Light Co
To:	Ziemann D Office of Nuclear Reactor Regulation
References
Download: ML18127B151 (12)

Text

NRC FOIIM 195 IZ.70)

U.S. NUCLEAR REOULATORY COM ION DOCKET NUMBER 50-335 NRC.DISTRIBUTION FQR PART 50 DOCKET MATERIAL FILE NUMBER TO:

Mr. Dennis L. Ziemann

'FROM:

Florida Power

& Light Company Miami, Florida Mr. Robert E. Uhrig DATE OF DOCUMENT 10776 DATE RECEIVEO 10/8/76 LETTER Q OR IjINANE

~OPT DESCRIPT)ON C3NOTORjZEO

@UNCLASSIFIED PROP INPUT FORM ENCLOSURE NUPBER OF COPIES RECEIVEO One signed copy I

Ltr. re their 8/3/76 ltr....concerning Conation of License J - Supplementary InfoIrmation..

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ACKNOWLEDGED BO NOT REMOVE SAFETY AvS xvaiED csD ~

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FLORIDAI CAPER 5 LIGHTCOMPANY Octobex 7, 3.976 L 76-352 Office of Nuclea Reactor Regulation Attn.

Dennis X. Ziemann, Chief Operating Reactors Branch Ha.

2 Division of Operating Reactoxs U. S. Nuclear Regulatory Commission Hashington, D. C. 20555

Dear Nx. Ziemann:

Re St. Lucie Unit No.

1 Docket No. 50-335 Operating License DPR-67 Condition of License J Su lementa Xnforrnation Our letter of August, 3, 1976 (L-76-281) presented Florida Paver 6 Light Company's position that Section J of Enclosure 1 to the St. Lucie Unit No.

1 operating license has been satisfied and requested its deletian fram the license.

The information presented herein is in support af that position and is supplementary to oux earlier transmittal.

The operating history of CEDE 44 and a description of inspec-tions planned during the present outage vere outlined in our letter of August 3, 1976.

A review af this operating history and of the inspection results obtained since oux'arlier letter has led to the postulation of several possible mechanisms for the inconsistent performance of CEDN 44.

These are discussed below:

1)

The resence of farci

material, such as palyeth-e ene or gr3.t, x.n the aver gripper mechanism of CEDN 44 could cause it ta bind, preventing proper operation.

Nith polyethelene, law temperatures would increase the possibility of malfunctioning since the substance would tend to stiffen with cooling.

Grit, however, would not exhibit this property and shouM consistently impair operatian at all operating temperatures.

The presence of any material should be visually detectable.

The lower gripper mechanism has been inspected internally using a boroscope and found to be clean and free of foreign znaterial.

Also,

To:

bennis L. Ziemann Re.

St. Lucie Unit No. l Condition of License J October 7, 1976 page 2}

3) the operating histoxy has been carefully reviewed.

Exercising of the grippex at elevated temperatures tends to improve its performance at Lover tempera-tures.

This is not characteristic of grit as pointed out above.

Neither would polyethelene exhibit this trait since, if pxesent, it would con-tinue to affect low temperature operation regardless of exercising.

These inspections, however," revealed nothing.

Based on these considerations, it is not likely that grit, polyethelene, or any other type of foreign material is present.

Ha in or surface deformities on the drive shaft g t, cause malfunct onxng at a part~cu3.ar CEA w th-drawal height...

The drive shaft portion of the CRT 44 CEA extension shaft was inspected and compared to othex'EDE drive shafts.

No anomalies could be identified.

Xikewise<

operating temperature appears to be a factor in the observed operation.

There is no reason, however, fex this cause to be temperature related.

Therefore, we conclude that warping or surface defects on the drive shaft. are not -responsible for its 3'emperature intermittent operation.

Electrical malfunctionin in the lower ri r coil could cause the lxftzng sync onxzation to be a ected.

After the uppex internal package was removed from the reactor during the present outage, electrical current.

was supplied to CEDN 44 and its operation was care-fully observed No mechanical or synchronization problems were seen. lt was concluded that electrica1 malfunctioning is not a probable cause.

At temperatures less than 300 P, the thermal ro erties of the drive shaft and lower ri er s eeve may, at

times, cause a misalignment of the mechanical latches and the drive shaft notches.

Upon attempted engage-ment of the gripper mechanism in this case, the latch may not seat properly into the notch on the shaft.

%lhen this occurs, the CEA is not properly latched an8, hence, is allowed to inadvertently dx'op.

Higher tem-peratures and the consequent physical expansion of the

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To:

Dennis I Fiemann Re St Lucie Unit No 1

Condition of License J October 7+ 1976 Page mechanism parts may increase the tolerance of the mechanism and, thus, allow normal operation.

Based on the operating history, on test results, and on visual observations, this is thought to be the most probable cause of the inconsistent operation of CEDN 44.

As ve pointed out in our earlier letter, the cold xod drop time testing has been successfully completed.

Also, FPX, has no intention of reinstating Technical Specification 3.3.0.3 which wouM permit low temperature criticality.

Therefore<

CBDH 44 serves only a shutdown function, making its d9.fficulty to drive the xod at low temperatures independent of safe operation.

Xn addition, PPL has reviewed the available operating and in-spection data and has concluded that an unsafe core configu-ration cannot result from failure of the gripper latch to seat

.in the drive shaft notch-On the contrary, when the magnetic field iri the gripper coil collapses following, the lifting

sequence, the CEA always returns to its inserted position unless heM by the latch.

This is supported by the operating history wh9.ch shows that the rod has never, at any ternperaturei been observed to stick or to fail.to re<<enter the core upon its release.

Furthermore, the xod has performed normally in all cases for temperatures above 350 F, and considerable im' provement has been recently observed in its ability to withdraw at lcreex temperatures.

As a shutdown rod, CEDH 44 is never moved or operated during criticality or during approach to criticality. After the rod is successfully withdrawn, it remains stationary in the com-pletely withdrawn position.

The gripper has never been observed to disengage other than during rod movement.

Even so, the unlikely event of rod drop from the fully vithdrawn position has been analyzed in Section 15.2.3 of the St.. Xucie Unit 1 FSAR and accepted by the staff in their SER dated March 1, 1976.

Combustion Engineering, the CEDE vendor, has likewise reviewed the test data and operating history.

They have advised FPL that there is no safety consideration that should require replacement of CEDN 44.

Also, its replaceraent vill, not increase plant reliability.

Xt is C-8's estimate that the cost of the replacement effort wouM be approximately

$200,000 which includes about 500 man-hours of labor.

Also, at the reactor head, the dose rate is

To.

Dennis L-Riemann Re=

St. Lucie Unit Ro.

1 Condition of License J October 7, 1976 Page 4

approximately 0.5 rem/hour, so the resulting total exposure vooM approach 250 man-rem.

C-E and FPL agree that;, since no substantial additional protection of the public health and

safety, and no increase in p1ant reliability Millresult from this repair, the financial costs and radiological exposure are unjustified-In conclusion, FPX does not p1an to replace CEM 44 during the present outage.

Based on our assessment that no unsafe con-dition exists, that no increase in plant reliability or additional protection of the public health and safety vill resu1t from replacement, and that the rod performance is con-tinually improving, ve believe that the intent of License Condition J has been met.

Therefore, in vie+ of the foregoing~

and the information presented in our letter of August 3, 1976.

FPL requests that Section J be deleted from Enclosure 1 to the St. Lucie Unit 1 Operating License.

Since cXeletion of Section J vill mike the replacement. of CEDH 44 unnecessaryp it is requested that your review of this proposal be completed by October 11, 1976.

Your timely reviev vil3. be appreciated

because, should replacement become necessary, a decision made after October 11 vill lengthen our Present outage.

Yours very truly, Robert R. Uhrag Vice President RZu/Nr.a/hlc cc:

Norman C. Hoseley, Region XX Bach R.

Newman, Esq.

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