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{{#Wiki_filter:Commonwe4t Edison Dresden Nuclear Power Station R.R. #1 Morris, Illinois*
{{#Wiki_filter:Commonwe4t Edison Dresden Nuclear Power Station R.R. #1 Morris, Illinois* 60450 Telephone 815/942-2920 BBS Ltr. # 334                                     April 21, 1~77 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.
60450 Telephone 815/942-2920 BBS Ltr. # 334 April 21, Mr. James G. Keppler, Regional Director Directorate of Regulatory Operation  
This report is being submitted to your office in accordance with the Dresden Nuclear Power Station Technical Specifications, Section 6.6.B.
-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.
Stephenson tation Superintendent   .
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  
Dresden Nuclear Power Station BBS:skm Enclosure cc:   Director of Inspection & Enforcement Director of Management Information &   P~ogram  Control Fi 1e/NRC APR 2 G1977
& Enforcement Director of Management Information  
 
&
L
Control Fi 1 e/NRC APR 2 G 1977 L
* l1 \
* 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 0 1 31 I 0 1 ° 1.:... I 0 I 0 I 0 I 0 I 0 1-1° I 0 I .1 4*1 1 11 I 1 I 1 I I 0 1 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 1 2 1 4 I 9 I I 0 I 4 1 1 I o I 71 7 I I 01 4j 212117 1 7 I 1 * *0 57 58 59 60 61 68 69 74 75 80 EVENT DESCRIPTION
LICENSE.E EVENT REPORT
[filfil I During control rod withdrawal operations at approximately 44% power, the unit 7 8 9 . lo1 3 1 I 013erato.r discovered that Rod Block Monitor (RBM) channels 7 and 8 were automatically 8 1 7 8 lol 4 1 .!;l __
                                  .. *CONTROL BLOCK:                             l 1
_____ (q{5 j *j!; .
91         I I I I 6
__ :_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_.--*
                                                                                                                                                            *   .dASE PRINT ALL REQUIRED INFORMATION)
_c_o_n_t_r_o_l
LICENSEE                                                                                                                       UC EN SE                     EVENT NAME                                                                 LICENSE NUMBER                                         TYPE                         TYPE
_ro_d_B.;..-_7_w_a_s_t_h_e_o_n_l
      ~I            I   I LI             0 1'-~1 1135 1 14 31       I 01° 1.:... I 0 I 0 I 0 I 0 I 0 1-1° I 0 I .1 4 *1 15 1 11     I 1I 1I            I 0
_y_o_t h_e_r __ i n_t_e_r_i_o_r_c_o.;..n_t.._r_o_l
1 11 7     89                                                                                                                                     25     26                         30         ;31     32 REPORT.       REPORT*
_r_od __ t h_a.,..t_w
CATEGORY                          TYPE         SOURCE                             DOCKET NUMBER                               EVENT DATE                               REPORT DATE
__ a __ s ____ s_Jl 7 8'9 PRIME. (continued) 80 . SYST.EM CAUSE COMPONENT.
      @TI]coN'T             I I I L!J L!:J I 01 s                                                           1 o 1~1 o 1 2 1 4 I 9 I               I 0 I 4 1 1 I o I 71 7 I               I7501      4j 212117 17                I 1 * *0                   57               58                 59             60             61                                         68     69                             74                                           80 EVENT DESCRIPTION
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
[filfil I             During control rod withdrawal operations at approximately 44% power, the unit 7     8 9 lo1 3 1 I             013erato.r discovered that Rod Block Monitor (RBM) channels 7 and 8 were automatically 7 89!:-'.---------------------------------~....;._----------__.J*
___
                                                                                                                                                                  .                                                            8 1
... pu ___
11                                                                                        8 lol 4 1 .!;l__.b_y.;..p_a~s_s_e~d=-a_n_d_i_n_d_i_c_a_te_d__e_d_g_e__,r_o_d_s_e_l_e_c_t_ed___w_h_e_n_i_n_t_e_r_i_o_r_c_o_n_t_r_o_1_ro_d_B_-_s_w_a_s_____~l 11 (q{5j *j!;.._ @.; ;:~;.; ; ~" )'" *~:; ; ;*c" 't-"e. ___~:_J_.__o_t__h__e_r._*.;..i_n....t.e_r_io__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.:....*i-'o_n_i_n_g--~1 8
___ 1_1 e_d_g_e_r_o:..,.d
7     8 9 lo Isl~ ~I__.,..,.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_th_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
__ s_e_1_e_c_t_e
              . SYST.EM                   CAUSE                                                                       COMPONENT.               COMPONENT COOE               . . COOE                               COMPONENT CODE                             SUPPUER               MANUFACTURER               VDLATlJN
__ d_11_i_nd-ic_a_t_io_n_f_o_r
(§0 I I I B I                           LlJ                     I II N I sI Tl R I u I                             ~              I G I 0 I8 I 0 I                   ~
____ j 1 ioj
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 1~*--w_a_s___t_h_e....,....c_a_u_s_e_.~o-f_t_h_e_._s...pu___r_ro_u~s--R_B_M_b_y_p_a_s_~_a_n_d___ e_d_g_e_r_o:..,.d__s_e_1_e_c_t_e__d__i_nd-ic_a_t_io_n_f_o_r____~I 11 11 j ioj j~_b_.~_*t_h__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___~l 1
__ c_o_n_t_r_o_l_r_o_d_s_B_-_7_a_n_d_B_-_s_.
8 7 8 9                                                                                                                                                                                                                     80 FACIUTY                                                                                                     METHOD OF .                                         ('continued)
__ 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
                *. STATUS                                     " POWER         .                   OTHER STATUS               DISCOVERY                               DISCOVERY DESCRIPTION EE1              l_Ll                             I 0 I 4 I 4 I *1.___N_A_ _ _ _-"                                           ~            I   See     11 Eve*nt Descr i pt i on 1*1 7 .a.           9                               10 .                     12 13                                         44     45         46   ,,.                                                                     80
__ nd_p_r_o_p_e_r_R_B_M
                  .FORM OF
___ 7 8 9 80 FACIUTY METHOD OF . ('continued)  
                  .ACTIVITY                     CONTENT rn RELEASED                     OF RELEASE                             AMOUNT . OF ACTIVITY                                                           LOCATION OF RELEASE
*. STATUS " POWER . OTHER STATUS DISCOVERY DISCOVERY DESCRIPTION l_Ll I 0 I 4 I 4 I
                      ~                                ~                l~_NA-.,,.;-----....J'                                                      NA 7      8        9                                     10 .         11                                                   44         45                                                                                     80 PERSONNEL EXPOSURES NUMBER                               TYPE             DESCRIPTION
* 1.___N_A ____ -" I See 11 Eve*nt Descr i pt i on 1*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._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___;.....;...__~--_J 7     8 9                           11             .12         .
[ill] I. o L ol 01 L.fJ .-=---*-N_A . _________________ 7 8 9 11 12 13. BO . . PERS.ONNEL
: 13.                                                                                                                                                     BO PERS.ONNEL *1NJURIES NUMBER                               OESCRl°PTION
* 1NJURIES NUMBER OESCRl°PTION
[ill] I 0 I           01 01.';::-*-*__._NA_*---------------~---~--~
[ill] I 0 I 01 01.';::-*  
7     a*s                           11         12                                                                                                                                                                       00 OFFSITE , CONSEQUENCES
-* __
  .E~L 7     8 9 NA 80 LOSS OR DAMAGE TO FACILITY TYPE             . DESCRIPTION 7EID8 9lLl                                  NA 10!::--------------------'--....--....;._--------------......:.--------8~0 PUBLICITY
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
[fill NA . 7 8 9 80 ADDITIONAL FACTORS Eifil 7 8 9
  . 7     8 9                                                                                                                                                                                                                 80 ADDITIONAL FACTORS Eifil 7 8 9
* N ;:; . 60 7
                          *N 60 7~B.9~.----,.-----------.--.------~~----------------....:...------_..:.....:...__......."--~                                                                                                                        ~    ED
__ .......
                                .. NA-'\1E~.~._,___J_e_f_f_e_r_y....,.R_._w_o_J_*n_a_r_o_w""'s_k_i- - - - - - - - PHONE: _ _E_x_t_._\..;;;~23);;;;;2;;;.___
ED ..
GPO   a 111.* a 117
_,_ __ J_e_f_f_e_r_y....,.R_.
 
_w_o_J_* n_a_r_o_w""'s_k_i  
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.
--------PHONE: __ E_x_t_.
The safety significance of this event was minimal because the RBM backs up p~ocedural rod selections. Although the Tech Specs require the RBM to be
GPO a 111.* a 117
* operab 1e 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 B~8, since both control rods are located one position i~side the core periphery. This is not a repetitive occurrence.
*
* 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)
(50-249/1977-9)
CAUSE DESCRIPTION (continued) operation was verif1ed before further withdrawals of control rods B-7 and B-8 were performed.
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 deem~d~)warranted. The Rod Block Monitoring system. was supplied by the General Electric Company.}}
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.}}

Latest revision as of 09:06, 24 February 2020

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
Commonwealth Edison Co
To: Kappler J
NRC/RGN-III
References
50-249/1977-9
Download: ML17252A271 (3)
v • d • e


Text

Commonwe4t Edison Dresden Nuclear Power Station R.R. #1 Morris, Illinois* 60450 Telephone 815/942-2920 BBS Ltr. # 334 April 21, 1~77 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 & P~ogram Control Fi 1e/NRC APR 2 G1977

L

  • l1 \

LICENSE.E EVENT REPORT

.. *CONTROL BLOCK: l 1

91 I I I I 6

  • .dASE PRINT ALL REQUIRED INFORMATION)

LICENSEE UC EN SE EVENT NAME LICENSE NUMBER TYPE TYPE

~I I I LI 0 1'-~1 1135 1 14 31 I 01° 1.:... I 0 I 0 I 0 I 0 I 0 1-1° I 0 I .1 4 *1 15 1 11 I 1I 1I I 0

1 11 7 89 25 26 30 ;31 32 REPORT. REPORT*

CATEGORY TYPE SOURCE DOCKET NUMBER EVENT DATE REPORT DATE

@TI]coN'T I I I L!J L!:J I 01 s 1 o 1~1 o 1 2 1 4 I 9 I I 0 I 4 1 1 I o I 71 7 I I7501 4j 212117 17 I 1 * *0 57 58 59 60 61 68 69 74 80 EVENT DESCRIPTION

[filfil I During control rod withdrawal operations at approximately 44% power, the unit 7 8 9 lo1 3 1 I 013erato.r discovered that Rod Block Monitor (RBM) channels 7 and 8 were automatically 7 89!:-'.---------------------------------~....;._----------__.J*

. 8 1

11 8 lol 4 1 .!;l__.b_y.;..p_a~s_s_e~d=-a_n_d_i_n_d_i_c_a_te_d__e_d_g_e__,r_o_d_s_e_l_e_c_t_ed___w_h_e_n_i_n_t_e_r_i_o_r_c_o_n_t_r_o_1_ro_d_B_-_s_w_a_s_____~l 11 (q{5j *j!;.._ @.; ;:~;.; ; ~" )'" *~:; ; ;*c" 't-"e. ___~:_J_.__o_t__h__e_r._*.;..i_n....t.e_r_io__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.:....*i-'o_n_i_n_g--~1 8

7 8 9 lo Isl~ ~I__.,..,.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_th_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 sI Tl R I u I ~ I G I 0 I8 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 1~*--w_a_s___t_h_e....,....c_a_u_s_e_.~o-f_t_h_e_._s...pu___r_ro_u~s--R_B_M_b_y_p_a_s_~_a_n_d___ e_d_g_e_r_o:..,.d__s_e_1_e_c_t_e__d__i_nd-ic_a_t_io_n_f_o_r____~I 11 11 j ioj j~_b_.~_*t_h__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___~l 1

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

  • . STATUS " POWER . OTHER STATUS DISCOVERY DISCOVERY DESCRIPTION EE1 l_Ll I 0 I 4 I 4 I *1.___N_A_ _ _ _-" ~ I See 11 Eve*nt Descr i pt i on 1*1 7 .a. 9 10 . 12 13 44 45 46 ,,. 80

.FORM OF

.ACTIVITY CONTENT rn RELEASED OF RELEASE AMOUNT . OF ACTIVITY LOCATION OF RELEASE

~ ~ l~_NA-.,,.;-----....J' NA 7 8 9 10 . 11 44 45 80 PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION

[ill] I. o L ol 01 L.fJ .-=---*-N_A._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___;.....;...__~--_J 7 8 9 11 .12 .

13. BO PERS.ONNEL *1NJURIES NUMBER OESCRl°PTION

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

7 a*s 11 12 00 OFFSITE , CONSEQUENCES

.E~L 7 8 9 NA 80 LOSS OR DAMAGE TO FACILITY TYPE . DESCRIPTION 7EID8 9lLl NA 10!::--------------------'--....--....;._--------------......:.--------8~0 PUBLICITY

[fill NA

. 7 8 9 80 ADDITIONAL FACTORS Eifil 7 8 9

  • N 60 7~B.9~.----,.-----------.--.------~~----------------....:...------_..:.....:...__......."--~ ~ ED

.. NA-'\1E~.~._,___J_e_f_f_e_r_y....,.R_._w_o_J_*n_a_r_o_w""'s_k_i- - - - - - - - PHONE: _ _E_x_t_._\..;;;~23);;;;;2;;;.___

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 p~ocedural rod selections. Although the Tech Specs require the RBM to be

  • operab 1e 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 B~8, since both control rods are located one position i~side 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 deem~d~)warranted. The Rod Block Monitoring system. was supplied by the General Electric Company.

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