ML20244A803

Nonroutine 30-Day Rept 75-04:deficiency Found in Scope of Analysis Utilized in Deriving Power Vs Rod Withdrawal Limits Per Tech Spec Figures-3.5-2a,2b & 2c.Mgt Review Underway

ML20244A803
Person / Time
Site:	Three Mile Island
Issue date:	04/09/1975
From:	METROPOLITAN EDISON CO.
To:
Shared Package
ML20244A797	List: ML20244A794 ML20244A799 ML20244A803
References
75-04, 75-4, NUDOCS 7911150545
Download: ML20244A803 (2)

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Metropolitta Edicen Corp ry

'lhree ::ile Island ? uclear Station, Unit 1 (D 1-1) "

Dac':2t i:o. 50-239 h -

5-1~ X Operating License !!o. DP3-50 H;2nroutine 30-Day 2e crt 75-O'; .

! notification of a Deficiency in Scope of ?calysia Utilized in Deriving Poear vs. Rod 'Jithdrawal Limits

1. D2nerird: ion of Def t.-iency

!ss a result of discrepancies diceovered by our I:uelear Stee.m Systen Supply (NSSS) vendor when ccaparing predicted ejected rod worth values with actual naasured values for another utility nuclear station (Rancho Seco), further investir;ations vere conducted to verify the adequacy of analyses done in this sere auaject ares. for our Three Mile Island Huelcar Station Unit 1 Paced on these further investigations it hec been dd"*md that:

a. the Enneho Seco d'ficioney is not re).eted to TMI-l in that

1. the problen at hncho Seco was due to having used " rod control" type plant rodels for what is c. " soluble boren" controlled plant, and

2. the correct " rod control" type codels were in fact used for T.MI-l (a "rra control" type plant), but,

b. there doen e:<ist a defi.cianev in. th_e sc.one of enalysi..t.that

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van utilized in deri,ing the Power vs. Rod Withdrawal linits cs contained in the 2:d-l Technical Speci ficatien figurec 3 5-2A, 23, and 2C, in that:

l. the anal:. -

.::c :ect]y enanced that ejected rod ucrlh:s

• decrea;ef. - : bt:~up u ;er tb basinnim of a core tye.1:-

(i . e . F: cr c.0-d sith hurrup, v.; thin each reload cycle),

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2. ba ned on t'd : t.c:.rption, -

subjenL Power vs. Rod Withd .nval '

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Jem 1 by ev - i d"r-: 3 o-Py the bef;innim; of cor.

i fc nituetic n , f ,

pg 3 $ a e  %% / p e 8

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1. . con :. . i .:e:2tlj , ' ' t ; ?bj e. -2 at: , 3. R- 2A , 23, and 2S are not tiequate t o e n .: u re th t.'. roda nec controlled no as to k e ep e *. e s - 6 U3 rrth I ") le3H than the Speci fi enL3 On

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2 .' Corrective Actions

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A conprehensiva. analysis of ejacted rod vorths as a function of tire in core life has been conducted, and as a result of this analysis it has been deternined that .

a. the present limits of Technical Specification figures 3 5-2A, 2B, and 20 have been, and vill continue to be, curricient to ensura. nat er " 3 the Specification 3.5.2.3 rod worth linits up to the time of control rod interchange (note: this is an evolution wherein the assigtr:ent of specific rods to controlling rod group circuits is physically rearranged, so as to alter the order in which indi ridual rods are withdrawn in a nanner which provides for a more uniform fuel burnup; also,- this evolution is currently scheduled for nid-May, 1975),

b. revised Technical Sp.:ification rigures 3 5-2A, 2B, and 2C vill be inplenented" prior to the first post control rod interchange reactor start-up which vill provide limits sufficient to ensu-e not exceeding the rod vorth limits of specification 3.5 2.3 for the time from control rod interchange to the first refueling, and

c. as may be necesser/ for operations subsequent to the first refueling, additional revisiens vill be made at later dates (

to the subject TA'I-l Technical Specification figures.

3 Preventative Actio n A nanagement review of the circumstances which led to this deficiency is still in progress and, as r.2y be appropriate, edditional preventative actions will be taken.

?

• ote: It is presently inticipo.ted that this requent for a change to the T:'I-l Tech::ical  ;~_......!_ vi ll '. - *itted to th;' M >

Eegulatory Co:.m.icaion by Apri; 11, 3975 I h

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