ML20099C343
| ML20099C343 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 11/05/1984 |
| From: | Jens W DETROIT EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| EF2-70038, IEB-84-03, IEB-84-3, NUDOCS 8411190493 | |
| Download: ML20099C343 (6) | |
Text
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301d Wryne H. Jens.
O
- Vice President Nuclear Operatens
- FermL2,
' 6400 North Dzie Hxjhway
,, AAn NeepM, Megan 48166 November 5, 1984
- Illc VII 013) sems EF2-70038 Mr. James G. Keppler Regional Administrator Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Keppler:
Reference:
(1) Fermi 2 NRC Docket No. 50-341 (2) NRC IE Bulletin 84-03
" Refueling Cavity Water Seal,"
August 24, 1984 j
Subject:
Response to NRC IE Bulletin 84-03
" Reactor Cavity Water Seal" This letter provides Detroit Edison's reroonse to Reference 2.
NRC-IE Bulletin 84-03, " Reactor Cavity Water Seal,"
requested that Detroit Edison evaluate the potential for and consequence of a failure of the reactor cavity water seal.
The attached report addresses these concerns.
This is Detroit Edison's final report on this item.
If you have questions concerning this matter, please contact Mr. Lewis Bregni, (313) 586-5083.
Sincerely,
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Mr.
P.
M.
Byron Mr. M.
D. Lynch Mr. R.
C.
DeYoung USNRC Document Control Desk i
NOV131984 1190493 841105 A
G CK 05000341 PDR
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Mr. James G. Keppler EF2-70038 I, WAYNE H. JENS, do hereby affirm that the foregoing statements are based on facts and circumstances which are true and accurate to the best of my knowledge and belief.
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WAWiE H y JENS Vice President luclear Operations fW day of //'hWau*J 1984, before me A
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On this v
personally appeared on Wayne H. Jens, being first duly sworn and says that he executed the foregoing as his free act and deed.
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N' Pu JAMES J. MORGMI fietary Public. Oakland County, MI My Commission Expires Jan. A 19112 ge y )k<we2~ f, j"'"'"
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r-THE DETROIT EDISON COMPANY FERMI 2 NUCLEAR OPERATIONS ORGANIZATION USNRC LICENSING DOCKET'NO. 50-341 RESPONSE TO NRC-IE BULLETIN NO. 84-03 REFUELING CAVITY WATER SEAL i
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NOVEMBER 1984 l
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_ Catroit Edison' Response to I&E Bulletin 84-03 w
NR'C REQUIREMENT:
Evaluate the potential for and consequences of a refueling-cavity water seal failure and provide a summary report of 7
these actions.
Such evaluations should include consider-ation of:
gross' seal failure; maximum. leak rate due'to.
- failure of active components such as inflated seals;. makeup capacity; time to cladding damage' without operator action;
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potential effect.on stored fuel and fuel in transfer;'and emergency operating procedures.
l DETROIT EDISON RESPONSE:
l Description of the Fermi 2 Refueling Cavity Water Seal At Fermi 2, the refueling cavity water seal consists' of the j
refueling bellows, the refueling bulkhead, and the drywell.
seal bellows.
The refueling bellows assembly connects the reactor vessel flange to the refueling bulkhead and consists l
of a cylindrical, one-piece stainless steel bellows.
The refueling bulkhead is a flat, circumferential plate which bridges the gap between the refueling bellows and the drywell shell.
It contains eight 12-inch ventilation ducts and two 30-inch manways equipped with watertight covers which are bolted closed for refueling outages.
The drywell' seal bellows assembly extends from the drywell shell out to the reactor cavity wall and consists of a cylindrical, one-piece stainless steel bellows.
All seal boundaries consist of welded steel and contain no active components.
The-refueling and drywell seal bellows are monitored by a leak l
detection circuit.
A 5 gallon per minute leak past either bellows will activate an alarm in the main control room.
1 The refueling bellows assembly consists of a Type 304 stain-less steel bellows, a backing plate, a spring seal and a removable guard ring.
The refueling bellows consists of a cylindrical, one piece stainless steel assembly.
The backing plate surrounds the outer circumference of the i
bellows to protect it and is equipped with a tap for testing and for monitoring leakage.
The self-energizing spring seal is located in the area between the bellows and the backing plate.
This seal is. designed to limit water loss in the event of a bellows rupture by yielding to make a tight fit i
to the backing plate when subjected to full hydrostatic pressure.
The guard ring attaches to the assembly and i
protects the inner circumference of the bellows.
The drywell seal is a one piece stainless steel cylindrical hellows seal.
It is welded to the drywell shell and reactor well steel liner.
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Detroit Edison Response to I&E Bulletin 84-03 A.
Potential for a Refueling Cavity Water Seal Failure 1.
Gross Failure:
As described above, the refueling bellow spring seal is designed to limit water loss in the event of a refueling bellows rupture by yielding to make a tight fit to the backing plate when subjected to full pressure.
This feature would limit the effects of a failure such as the one described in Bulletin 84-03.
2.
Failure of Active Components:
As described above, all bellows seal boundaries consist of welded steel and contain no active components.
Therefore, Fermi 2 is not susceptible to the type of failure described in Bulletin 84-03.
B.
Consequences of a Refueling Cavity Water Seal Failure General consequences:
By design, fuel in both the reactor vessel and the spent fuel pool storage racks is below the level of the ref ueling bellows.
In the event of a bellows failure, neither the fuel in the reactor vessel nor fuel in the spent fuel pool would become uncovered.
During refueling operations, a
single fuel bundle in transit between the reactor vessel and the spent fuel pool storage racks may be located above the level of the refueling bellous.
Alarm Response Procedures for "high refueling and/or drywell seal bellows leakage" require the operator to place the fuel bundle in a safe condition before suspen-ding refueling operations.
The safe condition refers to either the reactor vessel or the spent fuel pool below the level of the refueling bellows, 2.
Time to Clad Damage Without Operator Action a.
Stored Fuel (Vessel or Fuel Pool):
As discussed above, refueling bellows failure would not result in water level falling below the top of the active fuel.
Fermi 2 does not have a fuel transfer tube or any other mechanism which could drain the fuel pool as a result of a bellows failure.
b.
Fuel in Transit:
At any time, only one fuel bundle will be in transit between the reactor vessel and the spent fuel pool.
Fermi 2 proce-dures require that this fuel bundle be expedi-tiously restored to either the reactor vessel or spent fuel pool in the event of a loss of water from the refueling cavity.
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Cetroit Edison Response to I&E.Bulletin 84-03 3.
Emergency Operating-Procedures:
Alarm Response Proce-dures require that fuel bundles:in transit be placed in either the reactor vessel or1 spent fuel pool if there is indication of leakage past the refueling bellows.
Additionally, numerous methods exist to supply makeup water to the refueling cavity.
These include:
Control Rod Drive Pumps, Low Pressure Coolant Injection, Core Spray, Condensate Pumps and RHR Service Water Pumps.
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