ML19206B285
| ML19206B285 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/11/1978 |
| From: | Herbein J Metropolitan Edison Co |
| To: | Varga S Office of Nuclear Reactor Regulation |
| References | |
| GQL 915, GQL-0915, NUDOCS 7905080328 | |
| Download: ML19206B285 (3) | |
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moe k.p naasiss METROPOLI FAN EDISON COMPANY PCGT OFFICE BOX 542 READING. PENNSYLVANI A 19603
. ELEPHONF J15 - 929-F01 May 11, 1973 c
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Oirecter of Nuclear Peactor Regulaticn At:n-
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7args Light Water Reactors 3rsnch No. h U. S. Nuclea-Regulstery Ocnnicsion
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Dear Sir:
Three Mile Island Nuclear 3tatica Unit 2 ('"MI-2 )
Eccket No. 50-320 Cperating licanse No. OFR-73 The cecurrence, at Cryctal River 3, of tvc separsted Burnable ?cison Ecd t
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oi might cerar at Three Mile Island, Unit 2.
Althcugh such an event is not c -.3.4 4e.-a. d.' 4.W..' s-, ' ao a. d. 'y c. *. %.. s a*.. s.'av~ *m.~s a,...^v.
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m rerain in place. Of the varicus options available, we have late ined
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de'tices, which were recc.nended by E&a.
'.nese retafners have been de-signed and are undergoing test and evaluation at E&W.
Currently, it is cur intentien to install the retainers on all 3F? A's
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f CC-2 333 operation to date has been with three primary ccclant pu pc in a,_
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e cperstica vill be conducted with all four ecolant pu=ps in service.
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and cther 3&W 177 Mark 2h Fuel Assenbly plants an on vesr neasurenent of d
the fuel asse=bly 3FEA holadcvn latches 2: Crystal River 3, Ar?.ansas..uclear One-1, Oconee-2, it is ccnservatively es*d-=*ad *"st CC-2 can reliabl-f
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Resu2 : to date of the SW investigatica of the CF-3 event indicate that the separation of 3FFa's may be due to a long ter. v21r phencrenen causing
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hydraulic lift cc pared vitb tae wet wei.cht Of a 3PRA appears to be a primary f1ctcr in *he holddown latch wear rate.
Latt. hardness is also
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cf the same design used in all 3F4 177 FA reactors.
Analysis of the T'C-? 3FFA hydraulic lift force for four pump fiev in-dicates less ec=inal lift than at Crfstal :.iver 3.
The holddovn latet assembly minimun. hardness cn CC-2 fuel assemblies in also equal to or greater than ne hardness of the Crystal River 3 dolds vn labch assemblies vnich expe*ien.ed the highest wear.
Thus, 2C-2 can be expected to ex-perierce a 1cver wear rate than Crystal River 3 However, to account fer m aer undefined factcrc which =27 influence year rate, a facter of h has been applied te the highest wear rate cbserved a* Crystal River. Cn this basis, an allevable limit of 75 days of CC-2 fcur pump cperation has been oe+a.,.4-w.a.
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Jear data frc: Oconee 2 and A'I'-1 fcr fuel asse=blies which cpera.ted fcr as icng sa 600 full ficv days lard ccnfidence that the use of Crystal River wear data coupled with a safety ractor of h is consertative for CC-2.
Davis 3 esse with higher calcu. lated lift and cc parabl' ' '~u= holdicvn assembly hardness has cperated without incident for greater than 15C full ficv days.
Rancho 3eco, also with calculated higher lifts but with such higher minimum holddown latch assembly hardness cperated for greater than wo
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Cperaticn with three pumps precludes 3FFA net lift with a verf large cargin thus avoiding conditions under which vear can cecur. To iate, all cperation 4....r.. c-N.. s '. e a_ n v4.*.h ' c ^ o.' am~. -" ~a 4..
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~'hus, baced cn the ccasideraticns described above, there is a very lcv prcb-ability of a 3FFA separating frc a fuel 1ssembly in CC-2 before retainers are installed.
hese retainers vil_ insure 3FFA locking fer the remainder c.e
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action vould be taken. Lessez pcVer increasec vculd te with..
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In addition, the change in by-pass flev as a result of EPRA rencval, is
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"'he consequences of a 3FFA separating frc= the core are bounded by the results of the Ejected Ecd Accident analyced in the FSAR. The reactivit-vorch of a single EFFa is Only 30 to ' C",
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'~he concequence of a stuck centrol red assencly (C?.A) is a nor al design c _,.,., _ _., + 4. 3.
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s of fcur pump Operaticn; alsc, any consequences to the core frc= such a separation are bounded analyseu cen;ained in the MI-2 FSAR.
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