NRC-90-0074, Discusses Insp of Flash Tanks & Reactor Feed Pump Strainers. No Further Evidence of Moisture Separator Reheater Debris Discovered in Strainers,Stub Tubes,Wire Mesh or Structural Members
| ML20043A963 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 05/18/1990 |
| From: | Orser W DETROIT EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CON-NRC-90-0074, CON-NRC-90-74 NUDOCS 9005230348 | |
| Download: ML20043A963 (3) | |
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May~18' 1990' NRC-90-0074
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U.'S.: Nuclear Regulatory Commission'
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Attention:: Document Control' Desk-Washington, D.C.: 20555.
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References:
'(1)1 Feral,2 2
- NN: Docket-No. 50-341.
NRC License'No.~NPF.j
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(2) Confirmat'oryActionLehter, CAL-RIII-88-009, dated
. April 19, 1988.
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L (3). Detroit'Edisch Letter NRC-88-0116,1 L
dated April.-23,11988..
L(4); Detroit Edison' Letter NRC-89-0017, 5
dated February:15, 1989 (5) NRC Letter to Detroit Edison,.-
dated Aprili18, 1989.
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Subject:
Inspections of.the Flash Tanks and' Reactor Feed Pump I
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With regards to the previous Moisture' Separator' Reheaters'L(MSRs)-
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damage, Reference 2, Item 5.c,: states the following:-
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t "After startup from.the current ~ outage, and operation.for:some y
period of time at elevated: power l levels,: open-and/i_nspect the.
MSRs,-reactor. feed pump suction strainers and Flash Tank 1
. strainers for stub tubes,: damage,idegradation and; debris.at the
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first opportunity.provided-by.the unit beingLin cold.~ shutdown and of sufficient l duration to allow thefinspectionsLto.beJperformed.
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All subsequent. cold shutdowns.of sufficient-duration will' entail 11
,an; inspection of the reactor feed pump. suction: strainers and the Flash Tank strainers. Once' detected all stub. tubes and debris fi i
shall be removed."
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l The following preventive. maintenance (PM) events were established to-remove: residual _ debris from the Heater Drains and Feedwater systems as:
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- a result of. thetinternal failure of.the MSRe:-
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U. S. Nuc1cir R!gulatory Corcission
-May'18, 1990:
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NRC-90-0074 Page 2 Event No.-
W. R. No.
Descriptions
-NO38 NO38890725 South: Reactor' Feed Pump Suction ~ Strainer.
NO36 NO36890725-North Reactor Feed Pump
. Suction St*ainer NO26 NO26890125-North Flash' Tank NO28_-
NO28890125 Center Flash Tank NO30-NO30890125-South Flash Tank As a result' of the most recent, inspections performed-during the First '
Refueling Outage and_ documented on the'above noted_ work requests,;no further evidence of. MSR debris was found in the strainers, si.e.', stub.
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tubes, wire mesh, or structural members. -Similarly,~.the Flash Tanks were free of MSR debris. After full power operation and'under full flow conditions' for over 200 days,- the system is clean of MSR debris.
As a result of or
' upections to date, MSR debris is no longer believed to be a problem. As such, Detroit Edison is requesting your -
concurrence to cancel these'PM events.,
Also per Reference 2, Item 2, Detroit Edison. revised plant procedures to require that flow to the. reactor _ vessel be aligned through the s -
reactor feed pump (RFP) suction' strainers whenever the startup level'
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control valve is to be urd. The purpose of.this was to ensure debris g
was trapped in the,RFP strainers, thus protecting the startup level
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control valve (SLCV) and the. reactor vessel'from debris. intrusion.
Detroit Edison now requests NRC concurrence to eliminate this requirement and allow operational flexibility to_ bypass flow around the RFPs under^these operating conditions. -This,is. justified based on the following:
(1)
In Reference 4, Detroit Edison requested'NRC concurrence to halt the microscopic' inspections of'theVreactor-coolant' filterable solids for MSR debris (stainless steel-wool). This request was approved by your Reference.5 letter. This was based on the fact that reactor coolant sample results since mid-July 1988 indicated no evidence of stainless steel strands.
(2)
Nspections conducted after the. problem dealing with the reactor'vesse) revealed no evidence of MSR debris entering the vessel. Samples taken on the reactor water cleanup (RWCU) spent. resin (phase. separators). showed no traces of steel wool. The-RWCU delay volume was. removed,
. visually inspected and hydrolazed. These inspections /
hydrolaze samples showed no sign of MSR debris.
(3)
Two' inspections of the East and West MSRs, performed in September 1988 and September'1989, concluded that the previous modifications to.the' primary and secondary steam-distribution plates have effectively prevented the recurrence of MSR. damage.
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U.~S. Nuclear R2gulatory Co2aission
' ;May-18, 1990 a
NRC-90-0074 Page 3 Based on items (1)-through (3) above,. subsequent MSR debris.has not'been a' problem and future MSR damage is not expected,to occur.
We'will continue to meet these commitments until we' receive
- notification of your concurrence with our requests.
If you should; have any questions,: please contact Terry L. Riley, Supervisor.ofi Compliance and Special Projects,'at (313) 586-1684.
-Sincerely, fI cc:
A..B. Davis R.-W. DeFayette W. G. Rogers J. F. Stang Region III l
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