ML19270G359

LER 79-013/01X-1 on 790131:scram Received on Intermediate Range Monitor Hi-Hi Trip at Notch 26 of Rod 42-15.Caused by Notches Being Withdrawn Past Point Required to Achieve Criticality.Procedures Revised

ML19270G359
Person / Time
Site:	Hatch
Issue date:	05/25/1979
From:	Thomas Greene GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19270G357	List: ML19270G355 ML19270G359
References
LER-79-013-01X, LER-79-13-1X, NUDOCS 7906060213
Download: ML19270G359 (2)

Text

. .

PREVIDUS REPORT DATE 9-79 EONTROL DLOCK: I I l

l l l l

.h l (PLEASE PnlNT On itPE ALL n[OUIRED INFORMATION i

8 9 lG ALICEr.stt l ECODE li lH ll l@l0 lo lo lo lo lo lo lo lo In lo le Ib LicLN:,E Nur.'uta n l@4LicLNSE

.4 Il ll llT)vEIl JJl@lbi LAIl t8l@

OffT GJ #

%'n%6JI t. l@l 61 o l 5101010 DOCK E T Nu'.'u t R 3121164 l@lo b) 11131117 EVENT DATE lo l@lo 151215 d4 ia HEPORT DATE l 7191@ 5J EVENT DESCnlPTioN AND PROBABLE CONSEQUENCES h o 2 1 At 2135 CST while anproachina criticality with a noderator temnerature of 199.50F I O 3 l and with effectively no Xenon inventory. a scran was recaived on IP'1 Hi-Hi Trio I o 4 l as the result of a criticality with a period of less than five seconds. The scra Q O s I occurred at notch 26 of rod 42-15 which was the 39th rod to be withdrawn in the con- l 0 c l trol rod withdrawal sequence. This was originally repo-te'd.under Tech Soec Section 1 0 7 l 6.9.1.2.a.4.c. There were no personnel injuries or overacosures nor any release 1 0 a i of radioactive materials to the environment as a result of this occurrence. J E3 8 9 DE CODE SUSCO E COYPONENT CODE SJS dE SU DE 8 0 s 8

I R l 10B l@ IX l@ [JJ @ l 7 I Z l Z l Z l Z l Z l@ W@ [Z_J 9 11 12 13 Id 19, 2J

, SEQUE NTI AL OCCU R R E NCE F4E PORT REVISION LER EVE NT YE AR REPORT NO. CODE TYPE N O.

O ,agg/RO L7191 L-J l 011131 tr_] lolli  !! 4J I-I LLJ ,

_ 21 22 2J 24 26 27 28 29 L) 31 32 i K P A ON C PL ?T 9E T HOUR $ $ 0 IT F u 8 $ PPLIE M iF CT E

[X_j@l34Z l@

33 lCl@

35 W@

36 l0lOl1151 3J 40 l Yl@

41 W@ lZj@ lZ l9l9l?l@

42 43 44 4; CAUSE DESCntPTioN AND CORRECTIVE ACTIONS h 1:1011 The startun was beino conducted by a trainee under the sunevision of a licensed I i i l onera tor. Rod 42-15 was the fifth sequential ' rod to be witidrawn in R'.M / RSCS I i 2 I group 3. It was continuously withdrawn from notch 18 to 26a t which coint the reac- 1 I

i 3 l tor scrarred. Staff believes that the short period was att'ibutable to notches hav- 1 i 4 l ing been withdrawn past the point required to achieve criti ality. (continued)  !

8 9 6J STA S  % POV.ER OTHER STATUS DISCO FY OtE3VERv 0ESCRIPTION i 5 [C_j@ 10l0l0l@l N/A l l" A l@l Operational event l ACTiviiv COSTENT aELEAsEO or RELE AsE . Loc.nONcPsELEAsE @

i s 8 9

[lj @ ((J@l AuOUNT

.N/A Or 4CriviTv 44 l

45

@l N'A

$J l

to  :

PERSONNEL E XPOSUHES NUYBER TYPE OESCRIPTION -

i i lo o 10 l@LZJ@l N/A l

.' ,EccNNEt,~,UJ,Es nuestR OEsCniPTiO~e N/A 2276 279 i a 8 9 10101018l 18 12 53 i

'^c'""

'?#E ' " fat #7 ON' ' @ 790606094 3 i 9 Lz_J@l N/A l 8 9 to $3 DE SC Ft1P TION

• 2 o MtVEf81 Ix N/A l lllllllllll!l}

s 9 10 68 69 JJ 5 NAME OF PHEPAllER T. V. Greenn. Sunt. Pit. Fng._Scrv. PHOf2- 9I2-3b7-77bb ,

Georgia Power Company Plant E. I. Hatch BaxleyqGeorgia 31513

~

Cause Description and Corrective Actions (continued)

Addition of this excess positive reactivity caused the short period and the resultant reactor scram. , .

Operator license training presently thoroughly covers the effects of sub-critical multiplication and more than adequately instructs operators in how subcritical multiplication is affected as criticality is approached.

Operators are thoroughly schooled in how neutron monitoring system instrum-entation should respcnd as criticality is approached such that if critic-ality is approached while in RWM/RSCS groups 1, 2, 3, or 4 a notch and wait withdrawal scheme is employed. In the event that an impending critic-ality is not recognized and in the event that such criticality yields a

. reactor period to fast to be manually controlled by the operator, then neut-ron monitoring instrumentation is provided to limit the extent of the pow-er ascension and in fact cause a power reduction by scramming the reac-to_r. This is precisely what occurred on January 31.

It is our contention that no improvements in operator training nor admin-istrative controls would absolutely preclude recurrence of similar events in the future. Revisions to the normal startup and scran recovery proced-ures of both Units have been approved to incorporate a requirement to em-ploy a notch and wait control rod withdrawal scheme when it becomes appar-ent from the affects of subcritical multiplication that criticality is im-pending.

2276 280 .

I

-]