ML20100N029

Proposed Tech Specs Revising Table 3.6.3-1 Re Primary Containment Isolation Valves

ML20100N029
Person / Time
Site:	LaSalle
Issue date:	04/01/1985
From:	COMMONWEALTH EDISON CO.
To:
Shared Package
ML20100N027	List: ML20100N023 ML20100N029
References
NUDOCS 8504180057
Download: ML20100N029 (8)

Text

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TABLE 3.6.3-1 (Centinued) y 5 PRIMARY CONTAINM6NT ISOLATION VALVES .

E VALVE FUNCTION AND NUMBER' h

• x ,

1 d. Other Isolation Valves .

i U .1. - MSIV'Leakaos control System

- - g IE32-F001A, E, J, N ID) j; 2. Reactor Feedwater and RWCU System Return ,

! 1821-F010A, B #'*

i IB21-F065A, B y

l! IG33-F040 Residual Heat Removal / Low Pressure Coolant Injection System f I~ 3.

r 1E12-F042A, B,.C I.

, R

• IE12-F016A, 8 J j

' m 1E12-F017A, 8

• I- <!> IE12-F004A, 8 Ilg ) II I 1E12-F027A, BII)

'1E12-F024p3)B

• - IE12-F021 >

I 1E12-F302 I3)

, [- 1E12-F064A, 8 g 1E12-F011A,Bjg[ l l IE12-F088A, 8, C IE12-F025p3)B,C Ilf II IE12-F030 '

-) 1E12-F005 III

'! (g 1E12-F073A, 8 IE12-F074A, Bgj)-

IE12-F055A, B gj) 8

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1. 1E12-F036A, BIII -

1E12-F311A, 8 f *, IE12-F041A,8(kh(k)

IE12-F050A, B ,,

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• TABLE 3.6.3-1 (Continued) ,

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-PRIMARY CONTAINMENT ISOLATION VALVES g.

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~ VALVE FUNCTION AND NUMBER

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' MSIV' Leakage Control System g [. 1. ,

2E32-F001A, E, J. N(b) _

! 2'. Reactor Feetk. ater and RWCU System Return 2821-F010A, B M ,

' 2B21-F065A, B-2G33-F040 3

3. Residual Heat Removal / Low Pressure Coolant Infection System 2E12-F042A, B, C p .

R' 2E12-F016A, 8

• 2E12-F017A, B f 3

i T 2E12-F004A, B g III 2E12-F027A,Bjg #

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2E12-F021 1 2E12-F302 III g'

2E12-F011A,BjghI 2E12-F064A, Bg 2E12-F088A, B, C

, p 2E12-F025pl)B,C Ilf II i

2E12-F030

• -2E12-F005 III

'i 2E12-F073A, ~B Il}#

2E12-F074A, B II)#'

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,f ATTACHENT B LASALLE COUNTY STATION UNITS l'AND 2-TECHNICAL-SPECIFICATION CHANGE REQUEST

Background

LaSalle County-Station has a reactor feedwater system primary containment isolation valve arrangement.with three (3) valves per feedwater

line as'shown on UFSAR Figure'6.2-31 Detail (b) (See Attachment C). Each line has two.(2) check valves and a motor operated gate valve. This arrangment meets the intent of: General Design Criterion 55 on "other defined basis criteria". _ During the postulated loss of coolant accident, it-is desirable to maintain reactor coolant makeup from all sources of supply.

. This design' allows a reliable coolant makeup to the reactor vessel from the normal ~ source when required and prevents inadvertent isolation of the line.

When the plant was originally' designed, Commonwealth Edison believed that

'only_two isolation valves were required on these-lines per prior NRC interpretations of GDC 55 regarding feedwater make-up requirements dominating the_ isolation requirement.

To meet this design requirement Commonwealth Edison installed the imotor operated 821-F065A and 8 feedwater injection valves and the'special

~ positive closing check' valves 821-F032A and B which have air operated actuators.m Each motor operated ~fedwater injection. valve was supplied with power from an ESS power bus, and can be operated from the control room following a: loss of offsite electrical power. Each of the outboard

-positive-closing check valves has _ testability features to conform to 10'CFR

-50, Appendix J criteria. The feedwater line between the inboard and outboard feedwater check valves'a's well as the valves themselves were specially designed and constructed in accordance with Standard Review Plan 3.6.2-10, and ASE Section 3,'so as .to preclude the possibility of a credible feedwater line. break between the check valves (the "superpipe" criteria). The inboard feedwater check valves 821-F010A and B were not expected to be tested to

Appendix J criteria and were procured with a different leakage tolerance.

They.were installed only 'to prevent a significant loss of inventory in the -

event'of a feedwateriline break. . Subsequently,; prior to the issuance of the 1 Unit 1 operating license,'the: inboard feedwater check valves were required by

.NRR;to be tested to 10 CFR, Appendix J criteria,'as. containment. isolation

1. : valves, in~ addition to the other two' valves in these. lines. A low pressure seal' feature was therefore added to these -inboard -feedwater check valve: to imeet the' Type C, test requirement-.as designated in the. Technical l Specification.-

'On September 3,-1983 LaSalle County Station Unit;1 was shutdown for a brief_ cold shutdown outage to perform various maintenance and surveillance items. .While testing the reactor:feedwater lines per Technical Specification;

surveillance requirements L 6.1.2.d, it was determined that the reactor

~ feedwater inboard check valves 1821-F010A and B did not meet-Technical-

. Specification 3.6.l.2.b for primary containment .conbined leakage rate limit' for Type B and C tests.(0.6 La). . _

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s Following the first failure of the valves to pass a local leak rate

-test which was performed after approximately eighteen months of operation, we observed some damage to the original seal material, which we concluded was the result of machining the material rather than grinding it _ to tolerance.

We also concluded that the sharp edges around the pressure equalizing ports in the disk had cut the seal material in multiple locations. These sharp edges were ruoved.

Eecause of the difficulty of obtaining molded seal material as was used for the original' seals, the manufacturer supplied new seals which were extrudeu and the ends of the material were vulcanized together to form the seal. On November 3, 1983, following approximately another month of operation, the inboard feedwater check valves again failed to pass local leak rate tests. The inspection of the seals revealed a gap in each seal on the circumference, one about one-half inch long and the other about one and one-half inches in length, at the vulcanized points of the seals. The seal material in the "B' valve also appeared to be brittle with multiple minute

, cracks. A possible alignment problem that may have prevented the disk from closing squarely against the seal also contributed to type "C" test failure.

However, because of two successive failures of the valves to pass the local leak rate test criteria following operations, we felt that further i

relief from the Appendix J criteria should be sought for these valves while solutions to the existing problems could be found and further repairs and/or modifications could be performed.

On November 17,_1983 Commonwealth Edison requested a license amendment for LaSalle. County Unit 1 (teF-ll) to exempt the Feedwater Line

. Inboard Isolation Check Valves from Type C testing until Unit 1 startup after the first refueling outage (Reference (c)). On November 28, 1983 a confirmatory action letter (Reference (d)) was issued confirming Commonwealth Edison's_ commitments to provide corrective actions with regard to these valve failures. In this light the the license amendment was deemed unnecessary and

"not appropriate at the time".

On_ December 14, 1983, Commonwealth Edison responded to the confirmatory action letter (reference (e)). This letter fulfilled the requirements of actions A,B,C and D of reference (d). A follow up letter

~ (reference f) provided additional information on this subject and stated that

the only remaining concern is the long term qualification of the soft seats.

As'a result of these actions Commonwealth Edison believed that interim operation with the use of ethylene-propylene seals was acceptable.

-In= January 1984, Unit 1 was restarted afte the November shutdown iwith newly installed soft seals. In February,-1984 with the unit in another cold shutdown ~ outage the seals were_ inspected and found to be satisfactory.

The unit was subsequently restarted and operated until September 29, 1984 when the_ unit was shutdown for a maintenance / surveillance outage ~. ~The_ valves

_were tested and theiseals found to be acceptable (one valve failed the leak test due to bushing problems; however, the seal was intact and was not

.' replaced). The' unit had 5377 on-line hours during this period ~(> 7 months).

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. The qualification' testing for the ethylene-propylene and other seal i materials is in progress but not complete. It is expected to be completed prior to the first refueling outage in Unit 1. At that time a qualified seal will be installed in these valves.

4 DISCUSSION In March 1985 LaSalle County Station Unit 2 was shutdown for a cold shutdown outage to perform various maintenance and surveillance items. While testing the reactor feedwater lines per Technical Specification surveillance requirements 4.6.1.2.d, it was determined that the reactor feedwater inboard check valves 2821-F010A and B did not meet-Technical Specification 3.6.1.2.b for primary containment combined leakage rate limit for Type B and C tests -

(0.6 La). The ethylene-propylene seal for these valves was found in a condition which.did not allow the seal to perform in a leak tight manner.

-These soft seals had been in service for approximately 1 year from the initial criticality until the present outage. While the valves disks were not found fully sealed into the seat, it is felt that- the valve would close during the differential pressure conditions expected during postulated l accident conditions.

4 Due to the uncertainty of the life of the seals and there" ore the operability of the Unit 1 check valve soft-selas, the Unit 11821-F010B was a

tested on March 29 1985. The leakage rate was found to be excessive and subsequent inspection of the valve seal revealed a failure of the seal similar to those found failed in Unit 2.

T CONCLUSION Because the feedwater lines will still have two isolation v 21ves in each line which fully meet the requirements of Appendix J to 10 CFR aj, because the outboard motor operated' isolation valve is supplied with power from an ESS bus, and because the feedwater line between the two check valves

-is designed and constructed so as to preclude a credible line break, it is d

believed that no unreviewed safety hazard exists and that. compliance with GDC 55~1s not compromised. For LaSalle Units 1 and 2, therefore,' Commonwealth Edison proposed to change the Appendix A (Technical Specifications) to Licenses NPF-ll and W F-18 as indicated on the attached marked up page 3/4-6-32. . The leakage requirements of Appendix J will be met by currently valid Type C tests performed on two valves in each feedwater line; Feedwater Outboard Testable Check Valves (Item #19 B21-F032A and B, on Tech Spec Page 3/4' 6-27) and Feedwater Outboard Reraote Manual Isolation Valve (Item #2, B21-F055A and B;.on Tech Spec Page 3/4 6-32), and Reactor Water Cleanup-Return Valve (Item #2, 1G33-F040, on Tech Spec Page 3/4 6-32).- In addition the remote motor operated valves-821-F065A and B and RWCU valve G33-F040 will be administra- tively controlled as stated in the LaSalle FSAR Section-6.2.4.2.1:. "The' valve (s) is r5 mote manually closed from the main c~ontrol.

room to provide _long term leakagesprotection upon operator determination that continued makeup from the feedwater system is unavailable or unnecessary

'(after LOCA).

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. Commonwealth Edison:therefore concludes that .this proposed amendment contains no significant. reduction'in the margin of safety, that it is within j

.-_. ' the' original design of the' facility and does not' constitute a significant .

hazards consideration.~  !

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( s. NOTE: TC 1 DESIGNATES TEST CONNECTION.

1. UPDATED FINAL SAFETY ANALYSIS REPORT

-~ FIGURE 6.2-31 e CONTAINMENT VALVE ARRANGEMENTS

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-ATTACHENT D Significant Hazards. Consideration CommonwealthEd1sonhasevaluatedthe.proposedTechnical'Specifica-

' tion ~ Amendment ar:d' determined that it-does not represent.a significant 4

ThazardsLconsideration. Based on the criteria'for defining a significant hazards consideration established in'10 CFR 50.92, operation of LaSalle County. Station Unit 1 and 2 in accordance with the proposed amendment will-not:

Ji) ' Involve a significant increase in .the probability or consequences of an accident previously evaluated because two (2) other valves in th.e line

will be type C tested per the Technical Specifications, FSAR and Appendix J to 10 CFR 50 criteria and Commonwealth Edison believes this change is an acceptable alternative

to General Design Criteria 55.

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2)L Create the possibility of a new or different-kind of accident from any accident previously evaluated because:

a) 'The containment leakage criteria will still be met even with single failure'since two valves in the line will meet Appendix J criteria.

?b) 1The feedwater line break' accident will not be affected by.this change because the inboard check valve will still be able to prevent gross inventory loss if a feedwater line break were to occur, which

'is the original-design intent.

3) Involve a.;significant reduction in tne margin of safety because-the leakage criteria for the primary containment as a whole will'still meet-the leakage margins as required by Appendix J:to 10 CFR 50.- Commonwealth-Edison believes that two valves in each line which meet Appendix J criteria is an acceptable alternative to General Design Criteria 55 on

, the "other defined basis criteria."

Based on the preceding discussion,-it is concluded that'the proposed

. t systemichange clearlyz falls within:all-. acceptable criteria with respect to the system.or component, the consequences.of previously evaluated accidents

, , willLnot be -increased and the: margin of safety will not be decreased.

,. sTherefore, based on the guidance provided-in the Federal: Register and.the ML criteria established in~10 CFR~50.92(c),(the proposed change does not 1 constitute's significant hazards consideration.'

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