ML20092G461

Forwards Listing of Actions Taken & Activities Completed During Fall 1991 Refueling Outage,Per Generic Ltr 88-17, Loss of Dhr. Mod Ensures Availability of Hydrogen Monitoring Sys in Event of Loss of 125-volt Dc ESF

ML20092G461
Person / Time
Site:	Byron
Issue date:	02/10/1992
From:	Schuster T COMMONWEALTH EDISON CO.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
GL-88-17, TAC-M68727, TAC-M74547, NUDOCS 9202200147
Download: ML20092G461 (4)

Text

,

(

Commenroelth Edloon s-

' 1400 Oput Pl:cs -

Dowrutt Grove. Illinois 60515 l

February 10,1992 i

Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission WasNngton, D.C. 20555 i

Attn: Document Control Desk j

t

Subject:

L Byron Station Unit i Generlo Letter 8817 Implementation and Hydrogen Monitoring System Modification Tac Nos. M69727 and M74547 NBCLDochetNosu50-45L I

Dear Dr. Murley:

J The se of tNs letter is to provide the NRC Staff notification of co letion of two activities,$o which a commitment was made in prior correspondence. Both the activities were completed on Unit 1 during the Fall 1991 refueling outage. Attachments A and B contain -

a brief review of the activity / issue and the completion date, for Generic Letter 8817 Implementation and modification of the Hydrogen Monitoring System.

Please direct any questions you may have concerning these matters to this office.

t Respectfully, 1

bwCfNh&f Terence K. Schuster Nuclear Licensing Administrator

- Attachment',

- cc: A.H. Hsia Project Mana$t inspector, Byron r NRR -

W. Kropp Senior Reside A. Bert Davis - Regional Administrator Rill i:

180011 u

22hh 4

I P

l

'ZNLD/867/38-l l

.-....u..-

I ATTACHMENT A I

Generic Letter 8817: Loss of Decay Heat Removal i

The purpose of this Generic Letter was to increase reliability of decay heat removal (DHR) systems. Numerous events involving a totalloss or degradation of residual heat removal capability have occurred throughout the industry, The NRC lasued this generic letter pursuant to 10CFR50.54(d enhancements.f). The NRC required a two phase corrective action plan, exped and programme

}

Byron Station's response to the expeditious actions was transmitted to the NRC In a letter from f

R. A. Chrzanowski to T. E. Murley, dated December 30,1988. The foHowing actions were required:

j 1.

Provide training on Industry events involving loss of DHR.

2.

Provide administrative control to ensure capability to close containment following a i

foss of DHR event, j

3.

Provide two independent, continuous core exit temperature Indications when the head is on the vessel.

4.1 - Provide at least two Independent continuous RCS water level indications.

i 5,

implement procedures to avoid RCS perturbations while operating in a reduced inventory condition.

O.

Provide at least two means of adding inventory to the RCS in addition to the RHR I

system.-

.7.

Implement procedures and administrative controls to assure an adequate reactor

. head vent path is available.

8.

Im)lement adequate administrative controls to assure that all hot leg stop valves are l

no; closed unless a vent path is available.

E 1 All training,' administrative controls, procedure changes and modifications proposed in this letter are in place.

Byron Station's response to the programmed enhancements was documented in a letter from i

R. A. Chrzanowski to T. E. Murley dated January 31,1989.' The following actions were required:

i f

-I nx a

k.

t e

ZNLD/867/39

4 (Attachment A continued) 1.

Provido tellable Indication of paramotors that describe the state of the RCS including: two independent RCS levolindications, two Indopondent coro exit temperaturos, monitoring of the DHR system and visible and audiblo Indications of DHR system performanco.

2.

Develop and implomont enhanced operating procedutos covering reduced RCS inventory.

3.

Ensure sufficient equipment is operable or available to rnitigato a loss of DHR.

4.

Conduct an analysis to provido a basis for response timos for procedures and equipment used to mitigato a loss of DHR.

5.

Submit Technical Specification changes to enhance rollability of the DHR system including a reduction in DHR minlmum flow, removal of the autoclosure interlock and to permit availability of a safety injection pump.

O.

Reevaluato and refine item 5 of expeditious actions to assure the risk of a loss of DHR ls minimized.

Allof the above ocedure changes, analysis, modifications and Technical Specifications changes are in lace.

On September 27,1991, the NRC lssued Inspection Report 50 454/91020(DRP);

50-455/91020 DRP). In this report, the NRC concluded that allitems for Generic Letter 0817 woro closed w(ith the exception <" the tornoval of the RHR autoclosure Interiock (ACl) on U

1. The ACl modification was coinpleted during October 1991 Based on the above, all actions required for Generic Letter 8817 are complete and this issue is considered closed.

The NRC issued a supplernental letter on November 6,1991, that also addressed an item relating to Generic Letter 8817. In this report, the NRC stated that the effectiveness of the Generic Letter 8817 corrective actions could not be ludged because Byron has not operated with the RCS In a reduced invento condition since Lheir implementation. Therefore, the NRC toquired that we notify the NRC R lon ill office prior to entering mid loop operations. This commitment is being placed in p operating procedures. Based on this commitment, the is considered closed. (TI) 251N103 pertaining to the actions required for Generk, Letter 8817 Temporary instruction Gommitment3atisfied:

Removal via modification, of the RHR suction valvo high prossuro auto closure interlock for each of the Unit 1 RHR trains during BIR04.

Date.by_wh!cttcomm!tmentwas3atisuod:

October 31,1991 ZNLD/867/40

I ATTACHMENT B NRR Staff Concom regarding the Hydrogon Monitor System Design in July of 1989, the Byron Station NRC Sonlor Resident inspector identified a concem with the design of the Hydrogen Monitoring System and a statoment mado in the Byron /Braldwood UFSAR. The NRC staff questioned whether the Hydrogen Monitor design meets the sinplo failuro critorion. Specifically, the NRC staff was concerned that failure of one electrical t:SF dMslon, when the valves were closed, would prevent remote re-opening of one of the two Isolation valves In each line and thus result in the unavollability of the hydrogen monitoring system. The NRC staff requested that Commonwealth Edison propose a design change to the system that would ensure both ' containment intogrity and Indication of hydrogon concentration in the event of a single oloctrical failure.'

Byron Station proposed to implement a modification to resolve the NRC staff concern. The existing design was rovised by replacing the oporator for one of the two containment isolation valves in each line with an operator that falls opon t a loss of power. The affected valvos will be the Division 12 (22) valve In the Division 11 ( 1) hydrogen monitodng line (Valvo 1/2 and the Division 11 (21) vafvo in the Divisi n 12 (22) hydrogen monitoring line (Valvo PS229A{88). As indicated in the previous sontonco, an identical change is proposed for Byron 1/2 PS2 Unit 2. This new design providos for two hydrogon samplo lines each dependent on a single ESF division's power to perform its sampling function. At the same time, the containment isolation function can be achieved for both lines with only one operablo ESF division.

The modification ensures availability of the Hydrogen Monitoring System in the event of a loss of one electrical 125 Vdc ESF division. Two separate Class 1 E power suppilos will still bo utilized to power redundant containment isolation valves in series.

The modification for Unit I was cornpleted during 01R04. The modification for Unit 21s on scheduto for B2R03.

Commitmerd satisfied; implementation of the modification,Identiflod above, for each of the Unit 1 Hydrogon Monitodng Trains during B1R04.

Data by_wh!ch.1helommitmentwaa _ satisfied:

November 6,1991 ZNLD/867/41

-