ML19345E437
| ML19345E437 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 03/05/1968 |
| From: | Haueter R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Morris P, Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8101190284 | |
| Download: ML19345E437 (3) | |
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Dr. Peter L. Morris, Director Division of Ecactor Licensing U. S. Atomic EnerCy Co: nission Unchington, D. C.
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Dear Dr. I' orris:
Attention: Mr. D. J. Skovholt On January 8, 1968, an informationc1 letter was sent to you describing an inoperative control rod drive at our Big Rock Foint Plant, our evaluation of the problem, and our intention to continue operation until the refueling shutdown with the drive valved out of service in the partially withdrawn position.
Operations throuEh February 10, 1968 were without incident, at uhich time the Plant was shut down for refueling. Uc have now completed our inspection of the inoperative drive and our routine surveillance inspection of reactor vessel internals. The inspection shova all reactor vessel internals to be in good condition with no indication of cny vibration, unusual movement or component Several pieces of foreign material in addition to the foreign wear.
object in the F-5 drive noczle were also detected in the reactor vessel and were removed. A description of the foreign objects is as follows:
1.
The fuel bundles and channels around inoperative F-5 drive were removed and a " diameter stainless steel bolt about 3" long, but minus a head, was removed fram control rod drive no:: ale extension. Following removal of the bolt, the drive operated normally.
The drive was rencved and inspected and was in Eood condition.
The bolt was badly worn on both ends and obviously had been in the reactor for a long time. We are reasonably certain that it is a bolt from the upper grid guide structure that was some-how missed on the inventory and inadvertently left in the reactor during one of the several times when these bolts were replaced. The upper grid'Cuide structure was carefully $mspected during the present y
outage, and all bolts are intact.
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.e Dr. Peter L. Morris W rch 5, 1968 i
i internals for 2.
During the movement of fuel and cort the fuel and reactor internals inspection, it was also found,that control rod drive D-3 could not be withdrawn. Inspect an of the drive nozzleextensionrevealedanapproxinately}"x1/16": 2" piccc of Radiation stainless steel which was removed from the drive nozz.h. had probably level from this piece was very high, indicating that i been lodged in the inlet of a fuel bundle and had drop ad out, and down into the drive, during fuel movement. The drive ad operated normally up to plant shutdown.
Identification of a small piece such a.
- his is very difficult, houcver, we are reasonably certain that it a part of one These bevoled of the small beveled pads welded to the upper grid bar.o facilitato pads were a field modification to the upper grid bers nitial' core insertion of fuel bundles, after it was found, during to catch on the locding in late 1962, that the fuel bundles would ten (
top edge of the_ channel.
shows all Again, inspection of the upper grid ba2 were replaced beveled pads to be intact, however, two upper grid ba2 in 1964 due to dam 0Ee incurred during insertion of the special R & D instrumented fuel packages.
These grid bars have since been shippet off site for dispccal along with other radioactive wastes, so veri:. cation cannot be made.
3 Inspection of the thermal shield a: i supports choted one of the louer seal wedges to be missing. This ved:; was recovered from the bottom of the reactor vessel. The re.aining Zive vedccc were inspected and are in place and secure. These wedges ;2re installed, 11 on the thermal in conjunction with the installation of the new top st it.
(See page 3 of
- hield, to vedge open the bottom scal and disable the Third Semiannual Report of Operations, dated Dece.oct 24,1965.)
The wedges were tack uelded underwater to the thermal shield; a very difficult ueld. It is apparent that this particular cid was not complete and did not hold. General Electric calcula: sns on necessary the disabled flou area to prevent significant pressure drop acrost har. adequate.
louer seal indicated that three wedges would be more Surs :111ance of the Therefore, we do not plan to replace the vedge.
remaining vedges vill be continued at future refuelir. :s, along with other core internals.
- 4. Another piece of foreign material.tas discovered wedged between the vessel wall and the core support ) late. -This picco was removed and identified as an approximately 5" lo c piece of gasket This gasket material consists of 20-24 gaicc monel crimped material.
overabout1/16"thickasbestosfiller. The asbestor has been completely dis::olved out, indicating that the piece hos been in the reactor for a
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Dr. l'eter L. l'orric 3
I: arch 5,1968 lonc time. Thic material is not used in the primary r;/ctem-and it ic not presently known hou the piece could have Cotten into the reactor veccel. It nay have possibly come from the feed-water cyctcm, but could also have occurred during the extensive thermal abic1d mcdification vork donc durinc September, 1961; to Septcuber, 1965 le vill continue to uort c.t identifyinc the cource of thic cacket mate)lal.
5 One other piece of forcicn material was removed from the reactor, a chort piece of one turn of stainless etcel Fle::itallic machet Laterial. Tnic piccc ccre from the cacket rem: red frc= the IIo.1 re' ctor r circulatinc pump during its rebuild in !by,1907 Thic Cachet cc::.e out in cmall piecec and cne piece apparently ecc:. ped detection and vac left in the pump bowl.
On the bacis of the above invecticatial3, Ccncumer: Fower Canpany har concludcd that the reactor veccel internals, and the prinary cycter in cencral, are in cood condition with no indicationc of any or poten'ial problenc. Accordincly, reconctitution of veccel problem:
c internals and chech-out of control rod drivcc has beer. completed and reloadinc of the rcactor core is underway. Recumptior. of plant operation is planned en about Ihrch 13, 1968.
Yours very truly, ELH/mp R. L. Hauctcr Accictant Electric Product ~.on Superintendent - IIuclear CC: IIThornburC 9
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