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{{#Wiki_filter:Commonwe4t Edison Dresden Nuclear Power Station R.R. #1 Morris, Illinois* 60450 Telephone 815/942-2920 BBS Ltr. # 334 April 21, Mr. James G. Keppler, Regional Director Directorate of Regulatory Operation -Region JI I U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, 111 inois 60137 Enclosed please find Reportable Occurrence report number 50-249/1977-9. This report is being submitted to your office in accordance with the Dresden Nuclear Power Station Technical Specifications, Section 6.6.B. Stephenson tation Superintendent . Dresden Nuclear Power Station BBS:skm Enclosure cc: Director of Inspection & Enforcement Director of Management Information & Control Fi 1 e/NRC APR 2 G 1977   
{{#Wiki_filter:Commonwe4t  
L * l1 \ .. *CONTROL BLOCK: l 1 LICENSE.E EVENT REPORT 91 I I I I * .dASE PRINT ALL REQUIRED INFORMATION) 6 LICENSEE UC EN SE EVENT NAME LICENSE NUMBER TYPE TYPE I I LI 01 31 I 01 ° 1.:... I 0 I 0 I 0 I 0 I 0 1-1° I 0 I .14*1 1 11 I 1 I 1 I I 01 11 7 89 14 15 25 26 30 ;31 32 CATEGORY REPORT. REPORT* TYPE SOURCE DOCKET NUMBER EVENT DATE REPORT DATE @TI]coN'T I I I L!J L!:J I 01 s 1 o o 12 14 I 9 I I 0 I 41 1 I o I 71 7 I I 01 4j 212117 17 I 1 * *0 57 58 59 60 61 68 69 74 75 80 EVENT DESCRIPTION [filfil I During control rod withdrawal operations at approximately 44% power, the unit 7 8 9 . lo131 I 013erato.r discovered that Rod Block Monitor (RBM) channels 7 and 8 were automatically81 7 8 lol41 .!;l __ _____ (q{5j *j!; . __ :_J_. __ o_t __ h __ e_r._* .;..i _n .... t.e_r _i o __ r_c_o_n_t_r_o_l_r_o_d_s_w_e_re_t_h_e_n_s_e_l,....e_c_t_e_d_t_.o_c_h.,...e_c_k_t_h_e_f:..,.u_n_c_t.:....* 7 8 9 lo __.,..,.o_f.__t_h_,e_R_B_M_.--* _c_o_n_t_r_o_l _ro_d_B.;..-_7_w_a_s_t_h_e_o_n_l _y_o_t h_e_r __ i n_t_e_r_i_o_r_c_o.;..n_t.._r_o_l _r_od __ t h_a.,..t_w __ a __ s ____ s_Jl 7 8'9 PRIME. (continued) 80 . SYST.EM CAUSE COMPONENT. COMPONENT COOE . . COOE COMPONENT CODE SUPPUER MANUFACTURER VDLATlJN (§0 I I I B I LlJ I II N I s I Tl R I u I I G I 0 I 8 I 0 I 7 8 9 10 11 12 17 43 44 47 48 CAUSE DESCRIPTION (olal I Investigation revealed that a shorted diode in the control rod select circuitry I 7 8 9 . . 80 lolsl ___ ... pu ___ ___ 1_1e_d_g_e_r_o:..,.d __ s_e_1_e_c_t_e __ d_11_i_nd-ic_a_t_io_n_f_o_r ____ j1ioj __ c_o_n_t_r_o_l_r_o_d_s_B_-_7_a_n_d_B_-_s_. __ T_h_e_d_e_f_e_c_t_iv_e_d_io_d_e_._w_a_s_r_e_p_l_a_c_e_d_,_a __ nd_p_r_o_p_e_r_R_B_M ___ 7 8 9 80 FACIUTY METHOD OF . ('continued) *. STATUS " POWER . OTHER STATUS DISCOVERY DISCOVERY DESCRIPTION l_Ll I 0 I 4 I 4 I * 1.___N_A ____ -" I See 11Eve*nt Descr i pt i on1*1 EE1 7 .a. 9 10 . 12 13 44 45 46 ,,. 80 .FORM OF .ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT . OF ACTIVITY 9 10 . 11 44 rn 7 8 NA LOCATION OF RELEASE 45 80 PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION [ill] I. o L ol 01 L.fJ .-=---*-N_A . _________________ 7 8 9 11 12 13. BO . . PERS.ONNEL * 1NJURIES NUMBER OESCRl°PTION [ill] I 0 I 01 01.';::-* -* __ 7 a*s 11 12 00 OFFSITE , CONSEQUENCES . NA 7 8 9 80 LOSS OR DAMAGE TO FACILITY TYPE . DESCRIPTION EID lLl NA 7 8 9 PUBLICITY [fill NA . 7 8 9 80 ADDITIONAL FACTORS Eifil 7 8 9 * N ;:; . 60 7 __ ....... ED .. _,_ __ J_e_f_f_e_r_y....,.R_. _w_o_J_* n_a_r_o_w""'s_k_i --------PHONE: __ E_x_t_. GPO a 111.* a 117   
Edison Dresden Nuclear Power Station R.R. #1 Morris, Illinois*  
* * EVENT DESCRIPTION (continued) found to cause :a oypass of the RBM system. Withdrawal of control rods B-7 and B-8 was suspended and an investigation was initiated. The safety significance of this event was minimal because the RBM backs up rod selections. Although the Tech Specs require the RBM to be * operab 1 e above 30% power, the Tech Spec bases indicate that the RBM function is not necessary below 70% power. The significance was further mitigated by the core location of B-7 and since both control rods are located one position the core periphery. This is not a repetitive occurrence. (50-249/1977-9) CAUSE DESCRIPTION (continued) operation was verif1ed before further withdrawals of control rods B-7 and B-8 were performed. All other interior control rods have been successfu(ly checked for similar problems. This is the first rep0,r_ted failure of any of these diodes. No further corrective action was The Rod Block Monitoring system. was supplied by the General Electric Company.
60450 Telephone  
815/942-2920  
BBS Ltr. # 334 April 21,  
Mr. James G. Keppler,  
Regional  
Director  
Directorate  
of Regulatory  
Operation  
-Region JI I U. S. Nuclear Regulatory  
Commission  
799 Roosevelt  
Road Glen Ellyn, 111 inois 60137 Enclosed  
please find Reportable  
Occurrence  
report number 50-249/1977-9.  
This report is being submitted  
to your office in accordance  
with the Dresden Nuclear Power Station Technical  
Specifications,  
Section 6.6.B. Stephenson  
tation Superintendent  
. Dresden Nuclear Power Station BBS:skm Enclosure  
cc: Director  
of Inspection  
& Enforcement  
Director  
of Management  
Information  
&  
Control Fi 1 e/NRC APR 2 G 1977   
L * l1 \ .. *CONTROL  
BLOCK: l 1 LICENSE.E  
EVENT REPORT 91 I I I I * .dASE PRINT ALL REQUIRED  
INFORMATION)  
6 LICENSEE  
UC EN SE EVENT NAME LICENSE NUMBER TYPE TYPE I I LI 01 31 I 01 ° 1.:... I 0 I 0 I 0 I 0 I 0 1-1° I 0 I .14*1 1 11 I 1 I 1 I I 01 11 7 89 14 15 25 26 30 ;31 32 CATEGORY  
REPORT. REPORT* TYPE SOURCE DOCKET NUMBER EVENT DATE REPORT DATE @TI]coN'T  
I I I L!J L!:J I 01 s 1 o o 12 14 I 9 I I 0 I 41 1 I o I 71 7 I I 01 4j 212117 17 I 1 * *0 57 58 59 60 61 68 69 74 75 80 EVENT DESCRIPTION  
[filfil I During control rod withdrawal  
operations  
at approximately  
44% power, the unit 7 8 9 . lo131 I 013erato.r  
discovered  
that Rod Block Monitor (RBM) channels  
7 and 8 were automatically
81 7 8  
lol41 .!;l __  
_____ (q{5j *j!; .  
__ :_J_. __ o_t __ h __ e_r._* .;..i _n .... t.e_r _i o __ r_c_o_n_t_r_o_l_r_o_d_s_w_e_re_t_h_e_n_s_e_l,....e_c_t_e_d_t_.o_c_h.,...e_c_k_t_h_e_f:..,.u_n_c_t.:....* 7 8 9 lo __.,..,.o_f.__t_h_,e_R_B_M_.--*  
_c_o_n_t_r_o_l  
_ro_d_B.;..-_7_w_a_s_t_h_e_o_n_l  
_y_o_t h_e_r __ i n_t_e_r_i_o_r_c_o.;..n_t.._r_o_l  
_r_od __ t h_a.,..t_w  
__ a __ s ____ s_Jl 7 8'9 PRIME. (continued)  
80 . SYST.EM CAUSE COMPONENT.  
COMPONENT  
COOE . . COOE COMPONENT  
CODE SUPPUER MANUFACTURER  
VDLATlJN  
(§0 I I I B I LlJ I II N I s I Tl R I u I I G I 0 I 8 I 0 I 7 8 9 10 11 12 17 43 44 47 48 CAUSE DESCRIPTION  
(olal I Investigation  
revealed  
that a shorted diode in the control rod select circuitry  
I 7 8 9 . . 80 lolsl  
___  
... pu ___  
___ 1_1e_d_g_e_r_o:..,.d  
__ s_e_1_e_c_t_e  
__ d_11_i_nd-ic_a_t_io_n_f_o_r  
____ j1ioj  
__ c_o_n_t_r_o_l_r_o_d_s_B_-_7_a_n_d_B_-_s_.  
__ T_h_e_d_e_f_e_c_t_iv_e_d_io_d_e_._w_a_s_r_e_p_l_a_c_e_d_,_a  
__ nd_p_r_o_p_e_r_R_B_M  
___ 7 8 9 80 FACIUTY METHOD OF . ('continued)  
*. STATUS " POWER . OTHER STATUS DISCOVERY  
DISCOVERY  
DESCRIPTION  
l_Ll I 0 I 4 I 4 I * 1.___N_A  
____ -" I See 11Eve*nt Descr i pt i on1*1 EE1 7 .a. 9 10 . 12 13 44 45 46 ,,. 80 .FORM OF .ACTIVITY  
CONTENT RELEASED  
OF RELEASE AMOUNT . OF ACTIVITY  
9 10 . 11 44 rn 7 8 NA LOCATION  
OF RELEASE 45 80 PERSONNEL  
EXPOSURES  
NUMBER TYPE DESCRIPTION  
[ill] I. o L ol 01 L.fJ .-=---*-N_A  
. _________________ 7 8 9 11 12 13. BO . . PERS.ONNEL  
* 1NJURIES  
NUMBER OESCRl°PTION  
[ill] I 0 I 01 01.';::-*  
-* __  
7 a*s 11 12 00 OFFSITE , CONSEQUENCES  
. NA 7 8 9 80 LOSS OR DAMAGE TO FACILITY  
TYPE . DESCRIPTION  
EID lLl NA 7 8 9  
PUBLICITY  
[fill NA . 7 8 9 80 ADDITIONAL  
FACTORS Eifil 7 8 9 * N ;:; . 60 7  
__ .......  
ED ..  
_,_ __ J_e_f_f_e_r_y....,.R_.  
_w_o_J_*  
n_a_r_o_w""'s_k_i  
--------PHONE: __ E_x_t_.  
GPO a 111.* a 117   
* * EVENT DESCRIPTION  
(continued)  
found to cause :a oypass of the RBM system. Withdrawal  
of control rods B-7 and B-8 was suspended  
and an investigation  
was initiated.  
The safety significance  
of this event was minimal because the RBM backs up  
rod selections.  
Although  
the Tech Specs require the RBM to be * operab 1 e above 30% power, the Tech Spec bases indicate  
that the RBM function  
is not necessary  
below 70% power. The significance  
was further mitigated  
by the core location  
of B-7 and  
since both control rods are located one position  
the core periphery.  
This is not a repetitive  
occurrence.  
(50-249/1977-9)  
CAUSE DESCRIPTION  
(continued)  
operation  
was verif1ed  
before further withdrawals  
of control rods B-7 and B-8 were performed.  
All other interior  
control rods have been successfu(ly  
checked for similar problems.  
This is the first rep0,r_ted  
failure of any of these diodes. No further corrective  
action was  
The Rod Block Monitoring  
system. was supplied  
by the General Electric  
Company.
}}
}}

Revision as of 14:31, 29 June 2018

Dresden, Units 2 and 3, Transmittal of Reportable Occurrence Report No. 50-249/1977-9
ML17252A271
Person / Time
Site: Dresden  Constellation icon.png
Issue date: 04/21/1977
From: Stephenson B B
Commonwealth Edison Co
To: Kappler J G
NRC/RGN-III
References
50-249/1977-9
Download: ML17252A271 (3)
v • d • e


See also: IR 05000249/2019077

Text

Commonwe4t

Edison Dresden Nuclear Power Station R.R. #1 Morris, Illinois*

60450 Telephone

815/942-2920

BBS Ltr. # 334 April 21,

Mr. James G. Keppler,

Regional

Director

Directorate

of Regulatory

Operation

-Region JI I U. S. Nuclear Regulatory

Commission

799 Roosevelt

Road Glen Ellyn, 111 inois 60137 Enclosed

please find Reportable

Occurrence

report number 50-249/1977-9.

This report is being submitted

to your office in accordance

with the Dresden Nuclear Power Station Technical

Specifications,

Section 6.6.B. Stephenson

tation Superintendent

. Dresden Nuclear Power Station BBS:skm Enclosure

cc: Director

of Inspection

& Enforcement

Director

of Management

Information

&

Control Fi 1 e/NRC APR 2 G 1977

L * l1 \ .. *CONTROL

BLOCK: l 1 LICENSE.E

EVENT REPORT 91 I I I I * .dASE PRINT ALL REQUIRED

INFORMATION)

6 LICENSEE

UC EN SE EVENT NAME LICENSE NUMBER TYPE TYPE I I LI 01 31 I 01 ° 1.:... I 0 I 0 I 0 I 0 I 0 1-1° I 0 I .14*1 1 11 I 1 I 1 I I 01 11 7 89 14 15 25 26 30 ;31 32 CATEGORY

REPORT. REPORT* TYPE SOURCE DOCKET NUMBER EVENT DATE REPORT DATE @TI]coN'T

I I I L!J L!:J I 01 s 1 o o 12 14 I 9 I I 0 I 41 1 I o I 71 7 I I 01 4j 212117 17 I 1 * *0 57 58 59 60 61 68 69 74 75 80 EVENT DESCRIPTION

[filfil I During control rod withdrawal

operations

at approximately

44% power, the unit 7 8 9 . lo131 I 013erato.r

discovered

that Rod Block Monitor (RBM) channels

7 and 8 were automatically

81 7 8

lol41 .!;l __

_____ (q{5j *j!; .

__ :_J_. __ o_t __ h __ e_r._* .;..i _n .... t.e_r _i o __ r_c_o_n_t_r_o_l_r_o_d_s_w_e_re_t_h_e_n_s_e_l,....e_c_t_e_d_t_.o_c_h.,...e_c_k_t_h_e_f:..,.u_n_c_t.:....* 7 8 9 lo __.,..,.o_f.__t_h_,e_R_B_M_.--*

_c_o_n_t_r_o_l

_ro_d_B.;..-_7_w_a_s_t_h_e_o_n_l

_y_o_t h_e_r __ i n_t_e_r_i_o_r_c_o.;..n_t.._r_o_l

_r_od __ t h_a.,..t_w

__ a __ s ____ s_Jl 7 8'9 PRIME. (continued)

80 . SYST.EM CAUSE COMPONENT.

COMPONENT

COOE . . COOE COMPONENT

CODE SUPPUER MANUFACTURER

VDLATlJN

(§0 I I I B I LlJ I II N I s I Tl R I u I I G I 0 I 8 I 0 I 7 8 9 10 11 12 17 43 44 47 48 CAUSE DESCRIPTION

(olal I Investigation

revealed

that a shorted diode in the control rod select circuitry

I 7 8 9 . . 80 lolsl

___

... pu ___

___ 1_1e_d_g_e_r_o:..,.d

__ s_e_1_e_c_t_e

__ d_11_i_nd-ic_a_t_io_n_f_o_r

____ j1ioj

__ c_o_n_t_r_o_l_r_o_d_s_B_-_7_a_n_d_B_-_s_.

__ T_h_e_d_e_f_e_c_t_iv_e_d_io_d_e_._w_a_s_r_e_p_l_a_c_e_d_,_a

__ nd_p_r_o_p_e_r_R_B_M

___ 7 8 9 80 FACIUTY METHOD OF . ('continued)

  • . STATUS " POWER . OTHER STATUS DISCOVERY

DISCOVERY

DESCRIPTION

l_Ll I 0 I 4 I 4 I * 1.___N_A

____ -" I See 11Eve*nt Descr i pt i on1*1 EE1 7 .a. 9 10 . 12 13 44 45 46 ,,. 80 .FORM OF .ACTIVITY

CONTENT RELEASED

OF RELEASE AMOUNT . OF ACTIVITY

9 10 . 11 44 rn 7 8 NA LOCATION

OF RELEASE 45 80 PERSONNEL

EXPOSURES

NUMBER TYPE DESCRIPTION

[ill] I. o L ol 01 L.fJ .-=---*-N_A

. _________________ 7 8 9 11 12 13. BO . . PERS.ONNEL

  • 1NJURIES

NUMBER OESCRl°PTION

[ill] I 0 I 01 01.';::-*

-* __

7 a*s 11 12 00 OFFSITE , CONSEQUENCES

. NA 7 8 9 80 LOSS OR DAMAGE TO FACILITY

TYPE . DESCRIPTION

EID lLl NA 7 8 9

PUBLICITY

[fill NA . 7 8 9 80 ADDITIONAL

FACTORS Eifil 7 8 9 * N ;:; . 60 7

__ .......

ED ..

_,_ __ J_e_f_f_e_r_y....,.R_.

_w_o_J_*

n_a_r_o_w""'s_k_i

PHONE: __ E_x_t_.

GPO a 111.* a 117

  • * EVENT DESCRIPTION

(continued)

found to cause :a oypass of the RBM system. Withdrawal

of control rods B-7 and B-8 was suspended

and an investigation

was initiated.

The safety significance

of this event was minimal because the RBM backs up

rod selections.

Although

the Tech Specs require the RBM to be * operab 1 e above 30% power, the Tech Spec bases indicate

that the RBM function

is not necessary

below 70% power. The significance

was further mitigated

by the core location

of B-7 and

since both control rods are located one position

the core periphery.

This is not a repetitive

occurrence.

(50-249/1977-9)

CAUSE DESCRIPTION

(continued)

operation

was verif1ed

before further withdrawals

of control rods B-7 and B-8 were performed.

All other interior

control rods have been successfu(ly

checked for similar problems.

This is the first rep0,r_ted

failure of any of these diodes. No further corrective

action was

The Rod Block Monitoring

system. was supplied

by the General Electric

Company.

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