IR 05000313/2013012

Errata for Arkansas Nuclear One - NRC Augmented Inspection Team Follow-Up Report 05000313/2013012 and 05000368/2013012

ML14101A219
Person / Time
Site:	Arkansas Nuclear
Issue date:	04/10/2014
From:	Greg Werner NRC/RGN-IV/DRP/RPB-E
To:	Jeremy G. Browning Entergy Operations
Werner G
References
IR-13-012
Download: ML14101A219 (4)

Text

April 10, 2014

SUBJECT:

ERRATA FOR ARKANSAS NUCLEAR ONE NRC AUGMENTED INSPECTION TEAM FOLLOW-UP REPORT 05000313/2013012 AND 05000368/2013012

Dear Mr. Browning:

Please remove pages A3-8 and A3-9 from the NRC Inspection Report 05000313/2013012 and 05000368/2013012 and replace them with the pages enclosed with this letter. The purpose of this change is to correct an administrative error in the detailed risk evaluation associated with Unit 2. In accordance with Title 10 of the Code of Federal Regulations ns, s Rules of Practice, a copy of this letter, its enclosure, and your response (if any) will be available electronically for public inspection in the lable Records (PARS) component of the NRCs Agencywide Documents Access and Management System (ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).

Sincerely,

/RA/

Gregory E. Werner, Chief Project Branch E Division of Reactor Projects Dockets No.:

50-313; 50-368 Licenses No.:

DRP-51; NPF-6 Enclosure: Inspection Report 05000313/20130 12; 05000 368/2013012 Pages A3-8 and A3-9

Electronic Distribution for Arkansas Nuclear One

A3-8 t he fa ilure of once-through cooling. The evaluation of consequential loss of o ff site pow er provided a domina nt accide nt sequence involvi ng a transien t with consequential loss of o ffsite power, t he loss of all feedwater to t he stea m gener ators and fa ilure o f once-through cooling.

T able 2 Core D a m a g e S e q u e n c es S e q u e n c e De scr i pt i on P o i nt E s t i mate % of T ot a l Cut S et Cou n t M F W-14 I E M F W-F W-O T C 2.6 9 E-5 95.6 6, 0 3 6 LO O P-19 I E LO O P-E F W-O T C 3.7 9 E-7 1.3 1, 7 3 3 LO O P-20-09-10 I E LO O P-SBO(EP S)-R S U B-O PR08H- D G R08H-E F W M A N-S G D E P LT 2.7 4 E-7 1.0 527 M F W-15-10 I E M F W-R PS-F W A T W S 1.2 5 E-7 0.4 157 M F W-13 I E M F W-F W-SS RC-H P R 8.9 8 E-8 0.3 1, 6 7 9 LO O P-20-30 I E LO O P-SB O-E F W-O P R08H-D GR08H 8.0 0 E-8 0.3 959 M F W-02-09-04 I E M F W-LO S C-RCP T-H P I 6.1 4 E-8 0.2 814 M F W-15-11 I E M F W-R PS-RCS P R E SS U RE 3.9 9 E-8 0.1 18 M F W-15-09 I E M F W-R PS-B O R A T I O N 3.7 9 E-8 0.1 16 M F W-12 I E M F W-F W-SS CR-C S R 2.6 3 E-8 0.1 560 O th e r s A l l A d d i t i o n a l S e q u e n c es C o m b i n e d 1.3 3 E-7 0.5 3, 8 8 6 T ot a l CC D P A l l S e q u e n c es 2.8 1 e-5 1 0 0.0 1 6 , 3 85 A b b r e v i ati o ns B O RA TI O N Fail ure o f E m e r g e n cy Bora t i on CBO C o n tr o lled Bl e e d o f f I so lated CSR C o n t a inment S pray R ec i r cu l ati o n D G R 0 8 H N o n r ec o v ery of Di es e l G e n era t o r i n 8 H o u r s E F W E m e r g e n cy F e e d w ater E F W M A N M a n u a l C o n trol o f E m e r g e ncy F e e d w ater EPS E m e r g e n cy P o w er S y s t em FW F e e d w ater S y s t em (M F W , E F W , a n d a u x ili a r y f e e d w ate r) F W A T W S F e e d w ater S y s t em u n d e r AT W S C o n d i t i o n s HPI Hi gh Pre ssure I n j e c t i on HPR Hi gh Pre ssure R ec i r cu l a t i on I E L O O P I n i t i ati n g E v e n t: L o s s o f O ff s i t e P o w er I E M F W I n i t i ati n g E v e n t: L o s s o f M a i n Fee d w ater LOSC L o ss o f RC P S e a l C ooli ng O PR 0 8 H N o n r ec o v ery of O ff s i t e P o w er i n 8 H o u r s O T C O nce-T h r o u g h C o o li n g RCPT R e a c t or C o ol a n t P u m ps T r i p p ed RCSPRESS RC S P r ess u re L i m i t ed RSUB R e a c t or C o ol a n t S u b co o l i ng M a i nta i n e d RPS R e a c t or P r ot e c t ion S y s t e m SBO S t ati on B l a c k o u t S G DEP LT L a t e D e pr e ssuri z ati o n o f S t e a m G e n e r at o r s SSCR S ec o n dary C ooli ng R ec o v ered T he domina nt accident sequence cutsets involved a loss of mai n feedwater, loss of aux iliary feedwater , loss of emergency feedwater , a n d t he fa ilure of once-through cooling. T he t op t en sequence cutsets are provided in Ta ble 2 of the deta il ed risk evaluation.

A3-9 T he r esults are dominated by one core damag e seque nce. T he largest con tributor is Sequence 14 fr om t he loss o f main feedwater tree. The sequence comprises a fa ilure of all feedwater to the stea m gen erat or s , i nclu di ng main feedwater, aux iliary feedwater , and em ergency feedwater , with a loss of once-through cooling. T he remaind er o f the sequences ar e dominated by fa ilure o f the em ergency di esel gener ators without r ecover y of ac power. (6) Sensitivity An alysis T he SRA performed a variety of uncertainty an d sensitivity analyses on t he i nternal events model as shown below. The r es ults confir m the r ecommended Ye llow fin ding. Sensitivity An alysis 1 Transien t without Lo ss o f Main Feedw ater. T he SRA r an t he mod el us i ng a transient as t he initiator. T he change i n core damage frequency was 1.10 x 10-5 (Ye llow). Sensitivity An alysis 2 No consequentia l loss of offsite power.

T he SRA r an t he mod el witho ut i nclu ding t he additional runs to calculate the change in ri sk from a postulated consequentia l loss of o ffsite power.

T he change in core damage frequency was 2.

74 x 10-5 (Ye llow). Sensitivity An alysis 3 Potential R ecovery of B us 2A2 T he SRA r an t he mod el wi t h t he fa ilure of Bus 2A2 probability set to 6.79 x 10-1. This value, calculated using SPAR-H method ology , repr esent ed the probability that op erators wo uld fai l t o recov er t he bus prio r to core damage , giv en t he adverse and unknown conditions of s it e electrical supply. T he change in core damage frequency was 1.

97 x 10-5 (Ye llow). (7) Con tributions fr o m Externa l Events (Fire, Flooding, and Seismic) Manua l Chapter 0609, Appendix A, Sectio n 6.0 requires, whe n t he internal events deta iled risk evaluati on results are greate r tha n or equal to 1.0E-7, t he fin ding should be evaluat ed f or ext ernal event risk con tribution. T he analyst not ed tha t this deta il ed risk assessment evaluates an actual event i n which no external events occurred.

Ad ditionally, the period o f time that the events impacted plan t equipmen t was small enoug h tha t the probability of an ext ernal initiator occurrin g during this time wo uld be neg ligibl e. Theref or e , the ana lyst assum ed tha t t he risk from external events, giv en the subject perfo rmance deficiency was essenti ally zero.