ML20070P765

Proposed Pages to Tech Spec Change 88-03 Re Operability of PORV & Block Valves

ML20070P765
Person / Time
Site:	Sequoyah
Issue date:	03/22/1991
From:	TENNESSEE VALLEY AUTHORITY
To:
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ML20070P775	List: ML20070P765
References
NUDOCS 9103280092
Download: ML20070P765 (10)

Text

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e ENCLOSURE 1 REVISED TECHNICAL SPECIFICATION (TS) PAGES FOR TVA'S PROPOSED TS CHANGES 88 -03 LIST OF AFFECTED PAGES UNIT 1 4

3/4 4-28 3/4 4-30 d

UNIT 2 3/4 4-34 3/4 4-36 9103280092 910322 PDR ADOCK 05000327 P

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b. Wdk ene. PoRV.neperabic in MODES S er h dher @ restort %c.

in operaMe. PORV +o bfE29%E Status w$n 24 haves, or@ dinflefL de3ressurau % n anel ven+:n3 o F se Rcs %uf at leash a 3 synec a l b'f 3 2. hours.

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_LIMITiRO cowe7 TION FOR OPFRAT709 +c f Po in of r f e

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3.4

{. least one cf the following Overpressure Protecticn Systems shall 3

Two 'ower coerated relief valves (PCRVs) with'a nom 4.

p less than or ecual to that shown in Figure 3.4-4, ng or The Reac*er Coolant System (RCS) depressuri2ec with an RCS ven D

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dhe repert shall cescrite the circumstances initia y "'2Y3,

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.he previsions cf Specification 3.0.4 are not applicatie.

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below 3 lo. P SUF.VEILLANCE REOUIREP.ENTS II. I 4.4.0.:.1 Each PORV shall be demonstratec OPERABLE by:

fvHcTroaAL Perf ormance of an '"'.L:1. CHANNEL T:?.AT'.:. SAL TEST on the PORV a.

actuation channel, but excluoing valve coeration, within 31 days b

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nLE and at least once per 31 cays inereafter wnen the PORV is requitec OPERABLE; bl Performance of a CHANNEL CAllBRATION on the PORV actuation channel at least once per 18 months; and Verifhing tne PORV isolation valve is open at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> c.

wnes the PORV is being used for overpressure protection.

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t 3.4.-94 At least one of the following Overpressure Protection Systems be OPERABLI:

i=o p'ower operated relief valves (PCRVs) with a nominal lift a.

less than or ecual.to that shown.in Figure 3.4-4, or The Reactor Coolant System (RCS b.

p4ater than or ecual to 3 scuar)e inches.cepressurizec with an R 5 vent of A col!r4BIL Th': M00! 4 - ~ " mtu~ 9 :7 r:t ::':

M, MODE 5 anc MODE 6 with the reactor vessel heac on.

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Vith both PORVs, inoperable, cepressurize and vent the RCS th least a 3 scuare inch vent within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

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an ROS pressure transient, a Special Report s suomittec to the Commission pursuant to Spe 30 cays.

transient, the.ef fect of the PORVs or RCS vent (s) on the transient anc any corrective action necessary to prevent rancurrence.

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The provisions of Specification 3.0.4 are not applicable e, tdh e,, Rtc h,,,p.,.bre.

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SU;.vE!LLt.NCE REOUIREMENTS I

11. 1 4.4.-:.:.;

Each PORV shall be cemonstrated OPERABLE by:

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a.

Performance of ar ' "J. :0-CHANNEL-:?: n?'.:% L-TES~ on the PORV actuation channel, but exclucing valve coeration, within 31 days

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anc at least once per 31 cays thereaf ter wnen the PORV.is recluired OPERABLE; b.

Performance of a CHANNEL CAllBRATION on the PORV actuation channel at least once per 18 months; and Verifying tne PORV isolation valve is open at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> c.

wnes tne PORV is ceing used for overpressure protection.

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ENCLOSURE 2 pescription of Change By letter dated August 10, 1988, TVA submitted a proposed Technical

{

Specification (TS) change (TS Change 88-03) for Sequoyah Nuclear Plant (SQN) i Units 1 and 2.

TS Change 88-03 added low-temperature overpressure protection (LTOP) operability and surveillance requirements to SQN TSs.

Additional information that supported TVA's TS Change 88-03 was submitted by letters dated May 18, 1989, and November 16, 1989.

[

. contains two revised TS pages for both units that supersede the TS i

change pages that were previously submitted in TVA's August 10, 1988, and i

May 18, 1989, letters.

Reasons for Change

{

The revised TS change pages in Enclosure 1 are being submitted to implement i

the modified TS requirements of Generic letter (GL) 90-06 for SQN's LTOP system.

Justification for Change The NRC staf f determined that LTOP system unavailability is the dominant

[

contributor to risk from LTOP transients.

The staff further concluded that a i

substantial improvement in availability when ths potential for an overpressure event is the highest and especially during water-solid operations can be achieved through improved administrative restrictions on the LTOP system.

In developing the staf f position on the resolution of LTOP Generic Issue f

(GI) 94, " Additional Low-Temperature Overpressure Protection.f or Light-Water i

Reactors," a number of f actors have been taken into consideration.

I The staff considered the conditions under which an LTOP transient is scst likely to occur. While LTOP protection is required for all shutdown modes, I

the most vulnerable period of time was found to be Mode 5 (cold shutdown) with I

the reactor coolant temperature less-than or equal to 200 degrees Fahrenheit (F), especially when water solid, based on the detailed evaluation of l

operating reactor experiences performed in support of GI-94 LTOP transients that have challenged the overpressure protection system have occurrod with reactor coolant temperatures in the range of 80 degrees F to 190 degrees F.

In addition, a review of the standard technical specification for containment integrity indicates that there are no specific requirements imposed during Mode 5, when the reactor coolant temperature is below 200 degrees F.

Industry l

responses to GL 87-12. " Loss of RHR While RCS Partially Filled." dated

?

July 9,1987, also indicate that containment integrity during Mode 5 is of ten relaxed to allow for testing, maintenance, and repair of equipment.

i In addition, the staff noted that in all instances when P-T limits in the TS were exceeded, one LTOP protec4cn chana.1 was removed from service for maintenance-related activities.

During.these events, the redundant LTOP protection channel failed to mitigato th. overpressure transient as a result of a system / component failure that had nut been 6etected.

s I

1

. The reported LTOP transients have occurred in Mode 5 with reactor coolant system (RCS) temperatures ranging f rom 80 degrees F to 190 degrees F.

Since this temperature range includes Mode 6, the staff concluded that the additional administrative restriction for the single-channel allowed outage time (A0T) is applicable to Mode 5 and Mode 6 (with the reactor pressure vessel head on).

The staff concluded that the LTOP system performs a safety-related function, and inoperable LTOP equipment should be restored to an operable status in a shorter period of time.

The current 7-day A0T for a single channel is l

considered to be too long under certain conditions.

The staff concluded that l

the A0T for a single channel should be reduced to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when operating in Mode 5 or 6 when the potential for an overpressure transient is highest.

The i

operating reactor experiences indicate that these events occur during planned heatup (restart of an idle reactor coolant pump) or as a result of maintenance and testing errors while in Mode 5.

The reduced A0T f or a single channel in Modes 5 and 6 will help to emphasize the importance of the LTOP system in mitigating overpressure transients and will provide-additional assurance that plant operation is consistent with the design basis transient analyses.

Based on the foregoing NRC concerns, added assurance of LTOP availability is to be provided by revising the TSs for overpressure pr-tection to reduce the A0T for a single channel f rom 7 days to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when tne plant is operating in Modes 5 or 6.

In accordance with the above NRC staff position,_TVA la submitting three additional changes to TVA's previously submitted TS Change 88-03.

Thesc additional changes implement the modified TS requirements for LTOP as contained in Enclosure B of GL 90-06.

TVA proposed changes are as follows:

1.

Modify the action requirements to reduce the A0T for a single channel f rom 7 days to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the plant is operating in Modes 5 or 6.

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2.

Reformat the action requirements to implement a 31-day /12-hour verification of the reactor coolant system vent path that is being used

}

for overpressure protection.

(TVA's proposed TS_ Change 88-03 included the same requirement for verification of the reactor coolant vent path however, this requirement was formatted as a surveillance requirement rather than an action requirement).

3.

An SQN-specific footnote that suspends an action requirement for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> l

l Lo allow performance of Surveillance Requirement 4.4.11.1(a) is being I

withdrawn.

This footnote was submitted under TVA's August 10, 1988, i

letter and was necessary to allow a more reasonable timeframe for performing surveillance testing of the LTOP actuation channels.

Because I

of the automatic art'"g circuitry design that was in effect in 1988, i

performance of the sutveillance test.would cause both power operated relief valves (PORVs) to be inoperable, thus forcing required entry into

+

an 8-hour action for venting the reactor coolant system (RCS).

In the l

event surveillance testing could not be completed within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, TVA proposed adding a footnote to Action b to allow 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for testing.

The design of SQN's automatic arming circuitry has since been modified to a s

nanual arming configuration. This modification enables each PORV actuation channel to be tested independently, thus eliminating required i

l entry into-the 8-hour action. Accordingly, TVA is withdrawing the footnote on TS change pages 3/4 4-28 and 3/4 4-34 for TS Change 82-03.

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.. contains TVA's newly revised TS pages for both units.

These pages supersede the TS 88-03 change pages (3/4 4-28 and 3/4 4-30 [ Unit 1), 3/4 6-34 and 3/4 4-36 (Unit 21) that were previously submitted to you in TVA's August 10, 1988, and May 18, 1989, letters.. The additional changes provided in Enclosure 1 satisfy a SQN commitment contained in TVA's December 21, 1990, response to GL 90-06 (Enclosure 2. Commitment Item 3).

ENCLOSURE 3

[

t SIGNIFICANT HAZARDS EVALUATION i

TVA has evaluated the proposed technical specification (TS) change and has determined that it does not represent a significant hazards consideration i

based on criteria established in 10 CFR 50.92(c).

Operation of Sequoyah Nuclear Plant (SQN) in accordance with the proposed amendment will nott l

1.

Involve a significant increase in the probability or consequences of an i

accident previously evaluated.

By letter dated Augur,t 10, 196d, TVA submitted to NRC a proposed TS char 2e (TS Change 88-03) to add low-temperature overpressure protection (LTOP) operability and surveillance requirements to SQN's TSs.

Additional information that supported TVA's TS Change 88-03 was submitted by letters dated May 18, 1989, and November 16, 1989.

Because of recent modificatiens to LTOP TS requirements as reflected in Generic Letter (CL) 90-06, TVA is updatin6 and amending the information contained in TVA's August 1988 and May 1989 letters.

TVA is adopting two TS requirements for LTOP that are contained in CL 90-06, "Resolutior,of Generic Issues 70, Power-operated Relief Valve and Block Valve Reliability,"'and Generic Issue 94, " Additional Low-Temperature Overpressure Protection for Light-Water Reactors, Pursuant i

to 10 CFR 50.54(f)." By letter dated December 21, 1990, TVA submitted to NRC SQN's commitment for implementing the modified TS requirements for LTOP as contained in Enclosure B of GL 90-06.

The SQN-specific TS changes include the following.

l Modify the actic requirements to reduce the allowable outage time a.

(A0T) for a single 9annel f rom 7 days to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the plant is operating in Mode 5 or '..

I b.

Reformat the action requirements to implement a 31-day /12-hour verification of the reactor coolant system vent-path that is being l

used for overpressure protection.

An SQN-specific footnote that suspends-an action requirement for 24

}

c.

hours to allow performance of Surveillance Requirement 4.4.11.1(a) is being withdrawn. This footnote wes submitted under TVA's August 10, 1988, letter and was necessary to allow a more reasonable timeframe for performing surveillance testing of the LTOP actuation I

channels.

Because of the automatic arming circuitry design that was i

in effeet in 1988, performance of the surveillance test would cause both power operated relief valves (PORVs) to be inoperable, thus i

forcing required entry into an S-hour action for venting the reactor coolant system (RCS).

In the event surveillance testing could not be

)

completed within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, TVA proposed adding a footnote to Action b l

to allow 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for testing.

The design of SQN's automatic arming l

circuitry has since'been modified to a manual arming configuration.

This modification enables each PORV actuation channel to be tested i

independently, thus eliminating required entry into_the 8-hour action. Accordingly. TVA is withdrawing _the footnote on TS change

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3 pages 3/4 4-28 and 3/4 4-34 for TS Change 88-03.

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2 The SQN-specific changes described above are consistent with the modified LTOP TSs contained in Enclosure B of GL 90-06.

Other recommended TS changes from GL 90-06 were previously identifled and included in TVA s August 10, 1988, letter (TS Change 88-03).

The significant hazards evaluation provided in TVA's August 10, 1988, letter is not invalidated or altered by these additional changes.

Inclusion of the modified TSs from GL 90-06 provides a more conservative A0T requirement than TVA's previously proposed TS Change 88-03.

The SQN-specific change to relocate an existing surveillance requirement into the LTOP action requirements is editorial in nature.

Accordingly, the probability of accidents previously evaluated remains unchanged.

2.

Create the possibility of a new or different kind of accident from any previously analyzed.

TVA is amending TS Change 88-03 to implement inodif 2ed TS requi ?cments for LTOP as contained in NRC CL 90-06.

These SQN-specific changes include (1) a reduction in the LTOP A0T in Modes 5 and 6 f rom 7 days to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />; (2) shif ting an existing surveillance requirement (i.e., a 31-day /12-hour verification of the LTOP vent path) into the LTOP action requirements; and (3) withdtawing a footnote associated with a 24-hour allowance for surveillance testing.

The significant hazards evaluation that was provided in TVA's August 10, 1988, letter is nat invalidated or altered by these additional changes.

Inclusion of the modified TSs from GL 90-06 provides a more conservative A0T requirement than TVA's previously proposed TS Change 88-03.

The SQN-specific change to relocate an existing surveillance requirement into the LTOP cetion requirements is editorial in nature. TVA's withdrawal of the SQN-specific footnote results from a change to SQN's LTOP arming design and is considered necessary to retain standardized requirements that are consistent with GL 90-06.

Accordingly..

the probability of a new or different kind of accident from any previously analyzed is not created.

3.

Involve a significant reduction in a margin of safety.

l The significant hazards evaluation that was provided in TVA's August 10, 1988, letter is not invalidated or altered by these additional changes.

Inclusion of the modifled TSs f rom GL 90-06 provides a more l

conservative A0T requirement while the plant is in Mode 5 or 6.

The SQN-specific change to relocate an existing surveillance requirement into i

the LTOP action requirements is editorial in nature and does not impact I

the margin of safety.

TVA's withdrawal of the SQN-specific footnote results from a change to SQN's LTOP arming design and.is considered necessary to retain standardized requirements that are consistent with GL 90-06.

Consequently, the additional. changes to TVA's TS Change 88-03 would not involve a reduction in the margin of safety.

1

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