ML20155F058

Proposed Tech Specs Re Installation of Automatic Leakage Rate Detection Sys to Provide Continuous Pressure Testing of Containment Air Lock Door Seal Gaskets

ML20155F058
Person / Time
Site:	Byron, Braidwood, 05000000
Issue date:	10/04/1988
From:	COMMONWEALTH EDISON CO.
To:
Shared Package
ML20155F048	List: ML20155F044 ML20155F058
References
NUDOCS 8810130108
Download: ML20155F058 (8)

Text

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ATTACHMENT _A EROPOSED CRANGES TO APPENDIXJ IEC3HICAL_SEECIFICATION OF FACILLTI ,

DEERATING LICENSIS_HPF-37. AND NPF-66. NPF-72 and NPF-75 BYR0!LSTATION BRAIDWOOD STATLQH Revised Pages: 3/4 6-5 3/4 6-5 4

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i es10130tos es1004 P DP. ADOCK 05000454 p PDC

• s CONTAINMENT SYSTEMS SURVEILLANCE REQUIREMENTS 4.6.1.3 Each containment air lock shall be demonstrated OPERABLE:

a. Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following each closing, except when the air lock is geingusedformultipleentries,thenatleastonceper72 hours,by:

verifying seel= leakage =is=less=then=0.Ol= when-the-= volume 4etween

.the Acor= seals =is= pressurized =to-greater =t =orcequel=to=10:psigr.

fee-et=leest=15: minutes;:

b.

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By conducting overall air lock leakage tests at not less than P,,

44.4 psig, and verifying the overall air lock leakage rate is within its limit:

1) At least once per 6 months," and

2) Prior to establishing CONTAINMENT INTEGRITY when maintenance has been performed on the air lock that could affect the air lock sealing capability.**

c. At least once per 6 months by verifying that only one door in each air lock can be opened at a time,

1) Verifying that the seal leakage is less than 0.0024La (1.11 SCni) when the volume between the door seals is pressurized to greater than or equal to 3 psig by means of a permanently installed continuous pressurization and leakage monitoring system, or

2) Verifying that the seal leakage is less than 0.01La (4.63 SCni) as determined by precision flow measuremer.ts when measured for at least 30 seconds with the volume between the seals at a constant pressure of greater than or equal to 10 psig -

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i "The provisio of Specification 4.0.2 are not applicable.

"This represents an exemption to Appendix J of 10 CFR Part 50, Paragraph III 0.2(b)(ii).

BYRON - UNITS 1 & 2 3/4 6-5

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CONTAINMENT SYSTEMS SURVEILLANCE REQUIREMENTS

4. 6.1. 3 Each containment air lock shall be demonstrated OPERA 8LE:

a. Within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following each* closing, except when the air lock is being used for multiple entries, then at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, by:

werifying  :;e1 leek:ge is less-then-0.01-L,: v:1ume-betwee*-

- th; d::e-seal: 1: pras:;rked-to great:r t.. rhea-th Or :qw:1-to 10-p &

-fer et leest 15 ;inut;;;- ,

b.

By conducting overall air lock leakage tests at rot less than P,,

44.4 psig, and verifying the overall air lock leakage rate is within ,

its limit:

1) At least once per 6 months," and

2) Prior to establishing CONTAINMENT INTEGRITY when maintenance has been performed on the air lock that could affect the air lock sealing capability.**

c. At least.once per 6 sonths by verifying that only one door in each i air lock can be opened at a titse.

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l l 1) Verifying that the seal leakage is less than 0.0024La (1.11 SCni) when the volu:ne between the door seals is pressurized to greater than or equal to 3 psig by mean.s of a permanently installed continuous pressurization and leakage conitoring system, or I

( 2) Verifying that the seal leakage is less than 0.01La (4.63 SCni) as determined by precision flow reeasurements when reeasured for at least 30 seconds with the volu:re between the seals at a constant pressure of greater than or equal to 10 psig:

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'The provisions of Specification 4.0.2 are not appli:able.

• • This represents an eseeption to Appendix J of 10 CFR Part 50, Paragraph !!!

0.2(b)(ii).

BRAIDWOOD - UNITS 1 & 2 ,

3/4 6 5

a ATTACRMENT B D_eEfLiption_and_Sumaa.ry_of Proposed Changes.

The proposed changes involve Technical Specification I 4.6.1.3a, Containment Air Locks, that currently requires the containment air lock be demonstrated operable by the periodic pressurization of the volume between the door seals to 10 psig and verification that seal leakage is within limits. Byron Station has installed a modification on Unit 1 which would permit reduced pressure (3 psig) testing of the air lock door seals usi.mg a continuous pressurization and leakage monitoring system. The modification lavolved installing two separate instrument air lines, one each for bnth the laner and outer air lock door gasket interspace. The tubing is connected to the existing 1/4" fittings

. , ?r+.*y used to perform the type B testing. Installation of the

. c foc thu inner door required replacing the blind flange on a y >. )n through the air lock doct outer wall with a flant;e with 4- , . I a './7" pipe welded to it. Each of the lines provudes a

. " .i ir r t. : ++nt air supply of greater than or equal to 3 psig

- - tb 3 '001 casket interspace. The leakage rate of each air s " i< estitored by a common flow instrument. If excessive 3 u.a ; . 'ett'cted the condition will alarm in the control room. A c w mod .ue. 1.T te r is also located on the main control hoard for

!'gh ..

• c y.cssure alarms. These alarms will provide indication ci e s

. ' ar seal failure before exceeding the Technical

. vn t o?. limit on allowable leakage. ,

i The proposed change. *n allow reduced pressure testing and i con.im es monitoring, is in co..formance with 10CFR50 Appendix J.  :

Paragranno III.B.1 (c)and III.D.2.(b)(1-iv). The installation of ,

the automatic leakage detection system is expected to significantly reduce the radiation dosage to the personnel monitoring the leakage af the st 1s. The current manual testing of the door gaskets is manhour intensive and directly proportional to the frequency of containc.ent entry. The continuous monitoring, with main control +

oom alarms, would alleviate the 10CFR50 Appendix 3 requirements for  !

manual air lock tenting within 3 days of containment esqries during periois when containment integrity is rec uired by the plant's

!' Technical Specifications. This would recuce personnel exposure as

' ell as .)tovide for more eff ective use of Station manpower.

At this time, only Byron Unit 1 has implemented this  !

modification. The proposed Technical Specification change allows for either continuous monitoring or periodic local leak rate testing to satisfy the requirements as outlined in 10CFR50 Appendix J.

Therefore, this Technical Specification revision would allow the modification to be completed on Byron Unit 2 and Braidwood Units 1 and 2 without further Technical Specification changes.

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Byron's containment leakage rate testing system is similar to a system currently installed and used at Zion Station. Byron used the same method as Zion Station to extrapolate seal testing at reduced pressure to 10 psig to determine the allowed leakage limit.

This method was obtained from a Technical Evaluation Report -

Containment Leakage Rate Testing at Zion Station, dated June 8, 1981. The Technical Evaluation Report was prepared for the NRC by the Franklin Research Center. The Franklin Research Center reviewed the method for extrapolating the results of air lock testing at reduced pressures to larger pressures and determined that this extrapolation provides a conservative correlation between leakage rates. To extrapolate leakage flow rates in different pressure conditions, the following formula is used:

_b1_= P1 -1 L

2 P2 -1 Where Li = Leakage rate at pressure P1 (SCFH)

L2 = Leakage rate at pressure P2 (SCFH)

P1 = Pressure in areas where leakage ratt is L1 (ATM)

P2 = Pressure in areas where leakage rate is L2 (ATM)

Specifications 4.6.1.3a currently permits air lock testing at 10 psig with an allowed leakage rate of 0.01La. The continuous pressure testing will be performed at greater than or equal to 3 psig. Therefore the equation is reduced as follows:

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_blQ_ = (2hsl\

___14.7) = 4.05 L [11.1) _1 3

(14.7j L10 = 0.01 La where La = 463 SCFH as determined from the overall integrated containment leakage rate test. Therefore:

L3 = 1.14 SCFH The valve of L3 = 1.11 SCFH was conservatively selected for the Technical Specification valve.

This proposed change will not affect the overall air lock leakage test performed at the calculated peak containment internal pressure.

Pa, every six months. This leakage testing will continue to be performed as required by Specification 4.6.1.3b.

The second change proposed for Technical Specification 4.6.1.3a revises the wording to be more consistent with NUREG-452 Revision 5 "Standard Technical Specifications for Westinghouse Pressurized Water Reactors". Current Technical Specification wording requires the volume between the door seals be pressurized to greater than or equal to 10 poig for at least 15 minutes before verifying seal leakage is less than 0.01 La. However, the volume between the door seals is small and requires only a short time period to stabilize at a constant pressure :rather than 15 minutes. Therefore, the proposed wording change requires the volume between the seals to be pressurized to a constant pressure of greater than or equal to 10 psig and then to measure leakage for a period of 30 seconds.

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ATTACHMENT C Evaluation of Significant Hazards Considerations i

[ Commonwealth Edison has evaluated this proposed amendment and determined that it involves no significant hazards considerations. According to 10CFR 50.92(c), a proposed amendment

to an operating license involves no significant hazards  !

considerations if operation of the facility in accordance with the

proposed amendment would not:

s I (1) Involve a significant increase in the probability or  ;

3 consequences of an accident previously evaluated; or t

, (2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or l i

(3) Involve a significant reduction in a margin cf safety. l The proposed amendment involves two revisiens. The first [

! change revises wording in Specifiestion 4.6.1.3a to be more  :

i consistent with NUREG-0452 draft hefision 5 "Standard Technical  :

Specifications for Westinghouse Pressurized Water Reactors". The l second change reflects the installation of an automatic leakage rate i detection system to provide continuous pressure testing of the containment air lock door seal gaskets. This automatic leak rate detection system will monitor a:.r leakage and verify containment

integrity on a continuous basis with local indication and alarm in  ;

j the control room.

Containment air lock o erability is required to maintain I containment integrity and conta nment leak rate within required l limits. The lim:.ts ensure that the total containment leakage volume t

, will not exceed the value assumed in the accident ansivsis at the ,

accident pressure. The proposed Technical S7ecificati'on change will  !

permit manual testing using the existing Technical Specification or l

continuous testing through the installation of an automatic leak i

rate detection system, i f

Testing using either of these methods is consistent with  :

10CFR50 Appendix J. These testing methods are also in accordance  ;

4 with the descriptions provided in the FSAR. Both methods can i j adequately determinc containment air lock operability to ensure j

containment integtity is maintained. ,

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Revising the wording for the manual testing to be more 4

consistent with draft Revision 5 of the Standard Technical e Specifications simply clarifies the method of leakage detection, j Instead of pressurizing the volume between the door seals for 15 ,

2 minutes, the proposed amindment requires pressurization until a  !

constant pressure is achieved and then leakage is measured for 30 ,

i seconds. i l Therefore, the proposed change does not involve a j j significant increase in the probability or consequences of an .

accident previously evaluated. r I l

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The proposed change provides an alternate method for verifying containment air lack operability. Installation of the continuous leakage monitoring system utilizes the existing test fittings at the door gasket interspaces for performing the type B leakage testing. Therefore, installation of the alternate leakage monitoring system does not affect the sealing capability of the air lock door gaskets. It merely provides an alternate method to monitor air lock operability to verify containment integrity. The change to the existing Technical Specification wording Is a clarification in the method of testing and does not alter the i ability of the manual method to detect leaks. Therefore, the proposed change does not create the possibility of a new or .

j different kind of accident from any accident previously evaluated.

The osed amendment will allow air lock operability to beverifiedwfthn72hoursfollowingairlockopeningduring periods when containment integrity is required, as is currently '

i allowed by the Technical Specnfications, or by use of the continuous

, leakage monitoring system. The continuous leakage monitoring system is not intended to be a cubstitute for the 6 month test of the i' entire air lock at the calculated peak containment pressure related to the design basis accident pressure (Pa). The required overall air lock periodic leakage tests at not less than Pa (44.4 psig) will j still be conducted at least once every 6 months as required by the 1 i Technical Specifications. The proposed amendment can enhance the

verification of containment integrity through continuous monitoring i for air leakage by installation of the automatic leak rate detection system. This method allows detection of air lock leakage at all l times rather than the testing that is currently performed within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following closing of the air lock. Therefore, the proposed ,

amendment could increase the margin of safety by detecting air lock '

leakage in a more timely manner to facilitate maintaining I contannment integrity, i

l Changing the wording to be consistent with draft Revision 5 ,

j of the Standard Technical Specification does not affect the margin ,

of safety. The volume between the door seals is small and only

'j requires a short time period to stabilize at a constant pressure.

The manual testing will continue to be performed at a pressure of  ;

greater than or equal to 10 psig. Therefore, the proposed changes do not involve a significant reduction in the margin of safety.  ;

Based upon the preceding discussion, Commonwealth Edison l has determined that these changes involve no significant hazards considerations.

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