ML17252A291
| ML17252A291 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/22/1977 |
| From: | Commonwealth Edison Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| Download: ML17252A291 (3) | |
Text
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,'715J_ /I 3J (P. PRINT AU s:lEQUIRED INFORMATiO:
LICENSEE NAME @El I 1 I LI o I RI sj 31 7 B 9 14 REPORT CATEGORY TYPE *mrcu Ii T :-0 ..... 1 _0_..!_-_,IL-o_UCEN.1...I
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M ,' . . 15 25 2S 30 31 32 REPORT SOURCE OOClCET NUMBER EWl!IT CATE REPORT CATE @ill CON1' I I I LIJ tU 01 s I o I -I o I 2 I 4 I 9 I IOl4fT!IOl7171 I o1 41 212 17 17 -S{) 58 59 ..,_ "1esCRIPTION 60 61 68 69 74 75 @Ifilt::-J.___o_u_r_in-g
__ c_o_a_t_r_o_l_ro_d
__ w_i_t_h_d_r_a_w_a_l_op
__ c_1_a_t_i_&_As
__ a_t __ a_p_p_r_o_x_
... __ t ___ Q_"....;...4_4_%_p_o_w_e_r_, __ t_h_e_..., __
la1 3 j j operator discovered that Rod Block charineTis 7 and 8 were 7 as a.:..: [2E} __ b_Y_P_a_s_s_e_d...,.a_n_d
__ i .... n_d_i_c_a
... t_ed_'_'e_d_.g_e
__ r_o_d_s_e_l_.e_c_t_e_d_"_w_h_e_n_i_n_t_e_r_i_o"_rc_o_n_t_r_o_l_ro_d_B_-_a_w_a_s
____ _:_ 7 8 9 6C lolsl __
__ s_e_1...,e_*_te_&__,,t_e
__ c_1i_e_e_l<
__
(0 lsj 9:::-l _...__l5_r_c...,ll"":"e_P\_BA_.
___ o_t_he_r_.
- _, n_t_e_r_i:-Cll_ir_c_o_n_t_r_o_i_r_od_t_h_a":llt
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__ 7 8 9 SYSTEM CAUSE COMPONENT (cell ti bv JJ4..rJ,c, CODE COOE COMPONENT COOE 5lJPPIJER MANUFACTIJRER vtlLATllN f r [§0 I r I s I . LlJ I II N I s I Tl R I u I
- I G I o I 8 I o f L!J 1 a s 10 11 12 * .11 *
- 43 44 47 48 CAUSE OESCFHPTION . hwasti9atioa revealed tRa-tA shorted diode in the contrrol rod select circuitry . 7 8 9 SC (ojsj __ wa ........ s,..-t_h_e
__ c_a ... u_se __ o_f_t_h_e_s_pu_r_i
__ R_B_M_by_p_a_s_s._a_n_d_'_'e_d_g_e_r_o_d_se_l e_c_t_e_d_'
'_i .... nd_i c_a_t_i_o_n_, 7 8 9 a. f BG [!§ ..
u_*_*_e_d...,.s_.
_e_Y_a_*_*d_e_s_._r_h_e_d_e_e_c_t_i v_e_d_i_o_d_e_w_a_s_r_e_p_1_a_c_e_d_._a_'_'"-"-'_e_p_e_'_li\_1u_t
__ _; 1 ec . EE 7.8 rn 'ACIUTY *. STATUS L£J 9 ' POWER Io I 4 I 4 I 10 12 13
- ACTMTY CONTENT .. OTHEA STATUS NA 44 RELEASED OF REl.£ASE AMOUNT. OF ACTIVITY: l.__NA ____ __,J METHOO OF OISCOVERY 45 7 8 9 10 11 44 45 PERSONNEL EXPOSURES
- . NUMBER TYPE (!El_ I o I o I 01 W OESCRIPTION
- NA 1 8 s 11 . 12 13 PERSONNa INJURIES NUMBER* OESCRlPTION
('continued)
DISCOVERY OESCRIFTION I See E'>>'ent Description" 46 NA LOCATION.
OF RELeASI: 80 80 SC fIE] I o I oj oj
_____ --..;.._.;,.._
_ _...l . 7 8 9 11 12 SC OFFSITE CONSEQUENCES NA EE
- OAMAGE TO FACILITY TY1'£ OESCRIPTION Efilg_j 7 a s 10 s:_ PUBUCITY .. [ill] NA 1 8 s ( . ,, 7f:052001
- 3 ADOmONAL FACTORS mfil 7 8 9 i. N SQ lillJ _J 7 NAME:--Jeffery R. Wojnarowski
____ E_x_t_. ___ 43_2 ___
'. --* ',J ,'
- 175"13 EVENT DESCRIPTION (continued) found bypass of the RBM system. Withdrawal of control rods 8*7 and B-8 was suspended and an investigation was initiated.
The safety significance of this event was minimal because the RBM backs up procedural rod selections.
Although the Tech Specs require the RBM to be operable above 30% power, the Tech Spec base? indicate that the RBM function is not necessary below 70% power. The significance was further mitigated by the core locati-0n of B-7 and B-8, since both control rods are located one position inside the core periphery.
This is not a repetftive (50-249/1977-9)
CAUSE DESCRIPTION (continued) operation was verified before further withdrawals of control rods B-7 and B-8 were performed.
All other interior control rods have been successfully checked for similar problems.
This is the first reported failure of any of these diodes. No further corrective action was deemed warranted.
The Rod Block Monitoring system was supplied by the General Electric Company. < *: . ..... . ;
CONTROL
......
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.. ,_. (P.( PRINT AU . .;11;* UC EN SEE . NAME @El I I I LI DI RI 7 89 CATEGORY 1 0 LICENSE NUMBER sj 31 I 01 o 1-1 o I o I 0 I o I 0 1-1° I 0 I 14*. 15 25 REPOF'lT :l'PE REPORT soi.;i:icE (I 1 OOC><ET NUMBER 25 L.CENSE TYPE I I I * *E\IL'llT CA TE I 1 I 30 EVENT If PE I 0 I 1 1 31 32 ;;£;>OAT o.i. Tc @E]coN* I I I LLl LU I 01 s I o 1-1 o I 2 I 4 I 9 I !Ol4Jl!Ol7171 I 0 1 4 1 2 1 2 1 7 I* 7 . 8 57 58 59 60 61 68 69 74 75 ,, ... , . I' .., ) : EVENT OESCRIPTION c..,..I. -'*' , ' iJ 1 '.i II:; l /oj 2 J I During control rod withdrav1al operations 44% pmver, the unit 7 8 9 ! 0 1 3 1 ._I __ o_!)_e_r a_to_r _d_i _sc_o_v_e_r e_d __ t h_a_t_R_o_d_B_l o_c_k_M_o_n_*_, t_o_r_(_R_B_M_)_c_h_a_n_n_e_r_s_7_a_n_d_8_w_e_r_e_a_u_t_o_m
... a_t_i_c_a_1_1_y_* . . , 8 9 lal 4 j P_a_s_s_e_d_a_n_d
__ i n_d_i c_a_t_e_d_'_'e_d_g_,e_r_o_d_s_e_l_e_c_t_e_d_'_'
_w_h_e_n_i_n_t_e_r_i_c_r._c_o_n_t_r_o_i_r_o_d_B_-_a_w_a_s
____ J 8 9 . jojsj __ s_e_J_e_c_t_e_d_.
__
... e_c_k_t_h_e_f_u_n_c_t_i_o_n_i_n_g
__ _ __ o_f_t_h_e_...R_B_M_.
__ co_n_t_ro_J_ro
__ d_B_-_7_w_a_s_th_e_o_n_Jy_o_t_h_e_r
__ in_t_e_r_ic_r.
__ c_o_n_t_r_o_l_r_o_d_t_h_a_t_w_a_s
___ 8 9 PRME (continued) s sYSTI:M CAUSE COMPONENT COMPONENT COOE . CODE COMPONENT cooe SUPPIJER MANUFACTU;:l(R VOLATON I I I B I Ll.I I I I N I s I Tl R I u I I G I 0 I 8 I 0 l1J a s 10 11 12 17 43 44 41 48 CAUSE DESCRIPTION ajsj I Investigation revealed that a shorted diode in the contr.ol rod select circuitry . 8 9 s
- !'-j __
__ r_o_d_s_e_l_e_c_t_e_d_'
... ' _i_n_d_i_c_a_t_i_o_n
__ .qoj __ b_o_t_h_c_o_n_t_r_o_l_ro_d_s_B_-_7_a_nd
__ s_-_a_._r_h_e_d_e_f_e_c_t_._'v_e_d_i_o_d_e_w_a_s
__ r_e_p_l_a_c_e_d_,_a_n_d_p_r_o_p_e_r_R_B_M
____ c . ill ' a FACUTY STATUS LLl 9 ' POWER Io I 4 I 4 I 10 12 FORM OF ACTIVITY CONTENT OTHER .STATUS NA 13 44 RaEASEO OF RELEASE l2.I L.:J '----------J AMOUNT OF ACTIVITY NA .Ilfil . a 9 10 11 PERSONNEL .EXPOSURES NUMBER TYPE ill)lololol W DESCRIPTION NA a s 11 12 13 PEF1SONNEL INJURIES NUMBER OESCRIPTION 44 METHOO OF ('continued)
DISCOVERY DISCOVERY OESCRIPTION See 11[-i .. en t Description
45 46 9, NA LOCATION OF RELful.SE 45 s*
Oj OI 8 9 11 12 -OFFSrTE CONSEQUENCES ill) NA as LOSS OR OAMAGE TO fACILITY TYPE DESCRIPTION NA 8 9 PUBLICITY iE)
- tlA a a AOOITIONAL FACTORS !El NA 89