ML19347F154

Safety Evaluation Supporting Amend 55 to License DPR-36

ML19347F154
Person / Time
Site:	Maine Yankee
Issue date:	04/30/1981
From:	Office of Nuclear Reactor Regulation
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ML19347F150	List: ML19347F149 ML19347F152 ML19347F153 ML19347F154 ML19347F156
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NUDOCS 8105150344
Download: ML19347F154 (17)

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9 p ocq UNITED STATES o,

(9 ! i 3_3 c [ 7 NUCLEAR REGULATORY COMMISSION U

E WASHINGTON, O. C. 20555

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%,s SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION MAINE YANKEE ATOMIC POWER STATION AUTOMATIC INITIATION OF AUXILIARY FEEDWATER l

SYSTEM AND IMPLEMENTATION OF RECOMMENDATIONS i

FOR THE AUXILIARY FEEDWATER SYSTEM 1.0 Introduction Early in the review of the Three Mile Island Unit No. 2 (TMI-2) accident, it became apparent that increased plant safety would result from automatic initiation of auxiliary feedwater system

( AFWS) flow. This was short-term recommendation No. 2.1.7a of our July 1979 NUREG-0578.

In the implementation letters dated i

i September 13 and October 30, 1979, we provided clarification of requirement No. 2.1.7a and proposed control grade system installation by January 1,1980 with the upgrading of the automatic initiation of AFWS flow to safety grade by January 1,1981.

In response to the October 30, 1979 letter, some licensees raised the issue of the applicability of current analysis of a main steam line break or main feedwater line break assuming early initiation of auxiliary feedwater flow with a failure to limit flow to the affected steam generator.

In question was whether the chang'e in assumptions would increase the calculated containment pressure or the likelihood of return to power.

In a letter dated December 21, 1979 the NRC stated this concern regarding the applicability of current analyset for MSLB's under conditions of automatic initiation of auxiliary feedwater, and the staff requested that the licensee address this concern by submitting an analysis.

I&E Bulletin 80-04 dated February 8,1980, provided additional guidance to the licensee regarding reanalysis of the MSLS.

In response to the above letter and IE Bulletins, Maine Yankee submitted References 1 through 9 which describe plant modifications and analyses to support compliance with the staff's requirement to i

automate the AFWS.

i During our evaluation of Maine Yankee's modified auxiliary feedwater system, the following major concerns were addressed-1.

The licensee's request for a five minute delay to be added to the initiation of the AFWS';

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-2 2.

The licensee's consideration of single failure in his steam line break analysis; 3.

The implications of loss-of-offsite power (LOOP); and, 4.

The implication of the five minute delay in AFWS initiation on feedwater line breaks, LOCAs, and other transients.

The above items are reviewed in section 2 of this SER along with several other issues.

Our letter of October 18, 1979 presented the staff reliability evaluation of the Maine Yankee Atomic Power Station AFWS and mode short term and long term recommendations. Maine Yankee's responses to these recom-a mendations were submitted in References 10 throuch 16',

Our review of this information is presented in section 3 of this SER.

2.0 Discussion and Evaluati g 2.1 MSLB Accident - Return to Power The rationale for delaying the initiation of AFWS originates from the positive reactivity feedback which accompanies a postulated steam line break. During a pcstulated double-ended guillotine break in a steam line, the broken steam generator behaves as an enhanced heat sink, resulting in a rapid cooldown of the primary system. This rapid cooldown has a noticeable impact on the moderator reactivity feedback, which could result in a net positive reactivity. A conservative assumption is made that the limiting control element assembly is stuck in its fully withdrawn posi tion.

Based on the licensee's analyses, the reactivity feedback was limiting during zero power operation. During this condition, the coolant inventory in the steam generator secondary side is maximized and the decay heat is minimized.

The net energy removed from the primary system was conservatively assumed to be the product of the total steam generator secondary mass (MShould liquid times T

the latent heat of evaporation (H break, then the energy removed frh)the primary system will be less severe.

For a postulated guillotine break in a steam line, the time required to deplete the broken steam generator secondary inventory is approximately two minutes (for the zero power condition). Should the auxiliary feedwater be injected into the steam generator early in the transient,

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as for automatic initiation of the AFWS, then the magnitude of the where M is increased).

primary side cooldown is increased (M xhf This results in enhancing the primaryTgdecoS;lingandJQT an increased reactivity feedback.

The mechanism available for reversing the reactivity feedback is the initittion of ECCS, which injects boron into the system.

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The licensee has determined by analysis that a five-minute delay in the initiation of the auxiliary feedwater system will provide time for the ECCS injected borated' water to lessen the moderator reactivity feedback such that there will be nn return to power. Not allowing a return to power is more conservative than the NRC criterion for DNBR as stated in the Standard Review Plan for steam line break analyses.

The licensee has considered four different steam lire break cases; hot full power with and without auxiliary feedwater, and hot zero power with and without auxiliary feedwater. The five-minute delay after low steam generator water level signal was included in the two analyses with auxiliary feedwater.

Based on our review, we conclude that the proposed five-minute delay in auxiliary feedwater initiation is acceptable.

2.2 MSLB Single Failure Considerations In his reanalysis of steam line break, the licensee considered the effects of a single active failure in the safety injection system as directed by IE Bulletin 80-04 The licensee assumed the loss of one HPSI pump to be the most restrictive single active failure (in the safety injection system).

However, the licensee's reanalysis does not include the effects of the failure to close of the main feedwater regulating valves (MFWRV) or the MFWRV bypass valves. The licensee states that failure of one of these valves to close following a main steam line break would result in the potential for a return to power. As a result, the licensee intends to implement design changes during the next refueling outage scheduled for about June 1,1931. The design changes would provide a safety-grade closure signal from the low steam generator pressure excess flow check valve (EFCV) closure signal to the MFWRV and the MFWRV bypass valves.

Redundancy would be provided by a safety-grade signal to trip all MFW pumps upon receipt of a coincident safety injection actuation signal and any low steam generator pressure EFCV closure signal.

In conjunction with these changes, the auxiliary feedwater system will be automatically isolated from the affected steam generator following a steam line break, by a safety grade closure signal to the AFWS flow control valves.

This signal will be initiated by the low steam generator pressure EFCV closure signal. After this last change is implemented, the licensee intends to remove the delay in the AFWS automatic initiation circu' try since it will no longer be needed.

In the interim, until the above plant modifications are implemented, the licensee has provided a control-grade closure signal to the MFWRV and MFWRV bypass valves from the low steam generator pressure EFCV closure signal. He has also revised his emergency procedures to direct the operator to trip all MFW pumps and close the MFW motor operated valves should the MFWRV and MFWRV bypass valves fail to close.

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. We have reviewed the licensee's interim provisions to isolate the MFWS during a postulated steam line break and conclude that they are

- satisfactory at this time regarding the automatic initiation of the AFWS.

2.3 MSLB Accident - Loss-of-Offsite-Power (LOOP)

The licensee has not submitted calculational results concerning the consequences of losing offsite power during a postulated steam line break. However, LOOP was discussed by the licensee in his submittal dated April 17, 1980. The primary consequences resulting from loss-of-offsite power are a delay of ECC injection and tripping of the reactor coolant pumps.

During LOOP, ECC injection is delayed approximately 25 seconds as the emergency diesel generators restore power to the ECC pumps. Operation of the reactor coolant pumps would have two effects on a steam line break transient:

1.

Running the reactor coolant pumps would result in a greater degree of overcooling as the hot primary fluid is forced through the steam generators, and, 2.

The reactor coolant pumps would act as a driving head, forcing the ECC injected borated water into the core.

Thus, losing offsite power affects the degree of system cooling and the time at which ECC-injected baron enters the reactor core. Overcooling and borated water injection are competing effects in which the former increases reactivity and the latter reduces reactivity.

While the requirement to investigate LOOP during a steam line break is a cart of the Standard Review Plan, this requirement has not been explicitly addressed in the Maine Yankee docket.

In reviewing past analyses of steam line breaks for other plants similar to Maine Yankee, we have determined that losing power at the time of the steam line break was not as severe as having power available throughout the transient.

When forced circulation in the primary side is lost, the severity of primary overcooling is reduced as a result of losing forced circulation through the steam generators and the core.

The staff has reasonable assurance that Maine Yankee will behave similarly to other plants that have explicitly verified that a steam line break with LOOP would be less severe than having offsite power available. The staff will initiate an audit analysis' of a postulated steam line break at Maine Yankee to independently confirm this.

In order that the audit calculation be performed, the staff will require from the licensee certain input data as required for the RELAP code. An identification of the specific data needed will be provided in the near future.

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2.4 Implication of the AFWS Delay on Other Postulated Accidents For the automatic initiation of AFWS, Maine Yankee has proposed a five minute delay feature to reduce the severity of a postulated steam line break. Any adverse effects of the delay upon transients and accidents must also be evaluated.

For example, assuming liquid discharge from a ruptured feedwater line, the reactor would lose one out of three steam generators as a heat sink. A delay of AFWS injection could extend the heatup of the. primary coolant system; however, the intact steam generators require in execss of 15 minutes to boil dry and, therefore, provide adequate heat sink for decay heat removal beyond the five minute delay period proposed.

Maine Yankee has historically required the initiation of AFWS as a manual action. Whenever credit for operator action was required, the plant was shown to be independent of operator action for a minimum of 10 minutes. We therefore conclude that automatic initiation of the AFWS five minutes into the transient (verus 10 minutes, assuming operatur action) is appropriate and would not result in consequences worse than previously analyzed.

In his reanalysis of steam line break with automatic initiation of auxiliary feedwater, the licensee made a slight modification to his computer model noding. One node was removed from the main feedwater train to allow representation of the auxiliary feedwater header and to allow a proper distribution of the auxiliary feedwater flow. We conclude that the change is acceptable since our sensitivity studies have shown that such a noding change results in negligible impact.

The licensee's analysis included only breaks occurring at a steam generator nozzle inside containment to maximize break flow and cooldown effects of the primary coolant.

Breaks in steam lines outside of containment would be isolated by excess flow and non-return valves resulting in reduced primary side cooling and reactivity insertion.

We conclude on the above basis that the analysis limited to breaks inside containnent is acceptable.

The licensee's analytical methcd for analyzing steam line breaks is under staff review. The review results at this time indicate with reasonable assurance that conclusions based on the licensee's current submittal will not be appreciably altered by the completion of the analytical methods review.

In addition, audit calculations have been performed for previous operating conditions for a postulated steam line break at Maine Yankee that compared the results of the licensee's analytical method with those from the NRC's RELAP code, and the agreement was good.

Based on the above considerations, we conclude that the analysis submitted in support of the licensee's proposal to delay 411tiation of auxiliary feedwater by five minutes is acceptable.

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. Conclusions We find automatic initiation of the auxiliary feedwater system to inject needed makeup water to the steam generators without the need for operator action will improve the nuclear safety of the Maine Yankee plant. The staff plans to perform independent audit calculctions by the end of FY 81 to provide further confirmation of our conclusions.

2.5 MSLB Accident - peak Containment pressure By letter dated January 9,1980, Reference ll, Maine Yankee responded to our letter dated December 21, 1979. Specifically Maine Yankee was to assess the potential for containment overpressurization due to the anticipated continuous addition, at pump runout flow, of auxiliary feedwater to the affected steam generator following a postulated MSLB accident. Automating the auxiliary feedwater system would cause an increase in energy released to containment after a MSLB thereby increasing the containment pressure. The containment pressure response to a steam line or feedline break inside containment was not addressed in the Maine Yankee Final Safety Evaluation Report; however, by letter dated January 9,1980 the licensee stated that the appropriate analyses are contained in a report transmitted by their letter dated July 1977 which justified core power increase to 2630 degawatts thermal.

The licensee reported his analysis of a spectrum of steam line breaks inside containment at varicus power levels. In this analysis of the containment pressure response for steam line breaks inside containment, consideration was given to the effect of feedwater addition to the affected steam generator post-trip from the main feedwater system.

This analysis conservatively assumed 31% full power feedwater flow (8788 gpm) to the affected steam generator. This flow was based on an estimate of the bypass flow around the closed feedwater control valve.

Later tests showed that flow through the bypass valve is actually 20%

full feedwater flow (5660 gpm) which results in a margin of flow to the affected steam generator of 3123 gpm. The licensee believes the 3128 gpm margin in feedwater flow is sufficient to account for auxiliary feedwater run-out, low of 1775 gpm in the compartment pressurization analysis. The test results for flow through the feedwater control valve bypass line was obtained by a telephone conversation with the licensee on February 20, 1980.

Documentation of the test was verified by the resident I&E inspector on April 2,1981.

The staff concurs with the licensee's conclusion that the run-out flow for the auxiliary feedwater pumps is properly accounted for in the MSLB pressure analysis and that the peak containment pressure will remain

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below the design pressure even with the addition of auxiliary feedwater at run-out flow.

. 3.0 Licensee Response to NRC Recommendations In response to cur letters dated October 18, 1979 and December 21, 1979, Maine Yankee arovided responses tv our short term and inng term recommend-ations by Rsterences 10 through 16. Our evaluation of these responses is as follows:

3.1 Short Term Recommendations Recommendation GS-2 The licensee should lock open single valves or multiple valves in series in the AFW system pump suction piping and lock open other single valves or multiple valves in series that could interrupt all AFW flow. Monthly inspections should be performed to verify that these valves are locked -

and in the open position. These inspections should be proposed for incorporati;n into the surveillance requirements of the plant Technical Specifications. See Recommendation GL-2 for the longer term resolution of this concern.

Evaluation GS-2 In response to this recommendation, the licensee indicated in a letter dated November 20, 1979, that all manual valves in the AFW system necessary to assure flow from the primary water source to the steam generators are currently locked in the open position. Those valves have been added to the plant's ECCS locked valve check list and as such are inspected monthly.

The licensee submitted a proposed Technical Specification revision on February 22, 1980 which incorporated the locked valve alignment and flow path verification.

We have reviewed the licensee's response and conclude that the recommendation has been met and the Technical Specification revision is acceptable.'

Recommendation GS-4 Emergency procedures for transferring to alternate sources of AFW supply should be available to the plant operators. These procedures should include criteria to inform the operator when, and in what order, the transfer to alternate water sources should take place. The following cases should be covered by the procedures:

The case in which the primary water supply 's not initially available.

The procedures for this case should include any operator actions required to protect the AFW system pumps against self-damage before water flow is initiated; and, The case in which the primary water supply is being depleted.

The procedure for this case should provide for transfer to the alternate water sourcet.

prior to draining of the primary water supply.

. Evaluation GS-4 The licensee in a letter dated November 20, 1979, stated that existing emergency procedures will be upgraded to provide instructions for transferring to alternate sources of AFW supoly.

These procedures shall include criteria to inform the operator when, and in what order the transfer to alternate water sources should take place. The case in which the primary water supply is initially not available, as -311 as the case in which the primary water supply is being depleted, will both be covered. These procedure modifications have been completed.

We conclude that the licensee's response is acceptable pending verification by the Office of Inspection and Enforcement that the procedures are in place.

Recommendation GS-6 The licensee should confirm flow path availability of an AFW system flow train that has been out of service to perform periodic testing or maintenance as follows:

- Procedure should be implemented to require an operator to determine that the AFW system valves are properly aligned and a second operator to independently verify that the valves are properly aligned.

- The licensee should propose Technical Specifications to assure that prior to plant startup following an extended cold shutdown, a flow test would be performed to verify tne normal flow path from the primary AFW system water source to the steam generators. The flow test should be conducted with AF'J system valves in their normal alignment.

Evaluation GS-6 The licensee in a letter dated November 20, 1979, stated that the valves in the AFW system, by procedure, are olaced in their operational configuration as part of restoring the system to service following maintenance or testing. An independent verification of this valve alignment will be made. The licensee further stated that a Technical Specification change will be made by February 1,1980, to require a flow test of the AFW system prior to plant startup following an extended cold shutdown. The proposed Technical Specification change was provided by letter dated February 22, 1980. The Technical Specification change required a flow test prior to plant startup following an extended cold shutdown.

We conclude that this response including the proposed Technical Specification change is acceptable.

Recommendation GS-8 The licensee should install a system to automatically initiate AFW system fl ow.

This system need not be safety-grade, however, in the short-term it

-g-should meet the criteria listed below, which are similar to Item 2.1.7.a of NUREG-0578.

For the longer term, the automatic initiation signals and circuits should be upgraded to meet safety-grade requirements as indicated in Recommendation GL-l.

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- The design should provide for the automatic initiation of the auxiliary feedwater system flow.

- The autoniatic initiation signals and circuits should be designed so that a single failure will not result in the loss of auxiliary feedwater system function.

- Testability of the initiating signals and circuits should be a feature of the design.

- The initiating signals and circuits should be powered from the emergency buses.

- Manual capability to initiate the auxiliary feedwater system from the control room should be retained and should be implemented so that a single failure in the manual circuits will not result in the loss of system function.

- The alternating current motor-driven pumps and valves in the auxiliary feedwater system should be included in the automatic actuation (simultaneous and/or sequential) of the loads to the emergency buses.

- The automatic initiation signals and circuits should be designed so that their failure will not result in the loss of manual capability to initiate the AFW system from the control room.

Evaluation GS-8 We conclude that the licensee's response to this recommendation is acceptable for control grade AFW initiation. Verificas;on by the Office of Inspection and Enforcement that the system is installed and operable was made in October 1980. The long term counterpart of this recommendation GL-5 (safety grade) is not complete. We will provide our final evaluation of this matter in a supplement to this SER.

Recommendation 1 The licensee should propose a revision to the Technical Specification to require periodic AFWS operability testing on a monthly frequency rather than quarterly in conformance with current Standard Technical Specifications.

Evaluation 1 The licensee in a letter dated November 20, 1979, stated that proposed Change No. 67 to the Maine Yankee Technical Specifications, submitted March 28, 1979, would require in:ervice testing of valves and pumps classified as ASME Code Class 1. Class 2, and Class 3, in accordance with the approved edition of the Code.

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.. This would have the effect of requiring monthly operability testing of the AFW system.

We conclude that the licensee's response is acceptable pending Division of Licensing approval of the Technical Specifications submitted March 28, 1979.

Recomendation 2 A pneumatic-operated valve in the steam supply line to the turbine-driven AFW pump, and the three pneumatic-operated AFW flow control valves derive their power from the same A0 vital instrument bus.

Although these valves are designed to fail open upon the loss of air or power, thereby assuring auxiliary feedwater flow to the steam generators upon such losses, it cannot be concluded that all failures will result in opening the valves.

The consequences of voltage degrcdation should be analyzed as well as other failures (e.g., restricted air flow) to assure that such events would act incapacitate the auxiliary feedwater system. Establish suitable emergency procedures to assure AFWS function for such events.

(See Long-Term Recommendation Number 3).

In a letter dated November 20, 1979, the licensee stated that the consequences of voltage degradation on the operation of the pneumatic-operated valve in the steam supply line to the turbine-driven AFW pump and the three pneumatic-operated AFW control valves will be to open the valve. The consequences of air flow restrictions or loss of air are to open the valve.

These events would not incapacitate the auxiliary feedwater system.

Evaluation 2__

We conclude that the licensee's response is only partially acceptable.

We require that the licensee establish suitable emergency procedures for operation of the pneumatic-operated valves in the AFW system in the event the valves were to fail closed due to an unanticipated failure mode of the common AC vital bus. We will provide our final evaluation of this matter in a supplement to this SER.

Recommendr. tion 3 The licensee should verify that the air accumulator will hold the containment isolation valve in the turbine driven pump steam supply line open for at least two hours following loss of all AC power.

Evaluation 3 In a letter dated November 20, 1979, the licensee stated that a test to confirm that the air accumulator will hold the air operated valve in the turbine driven pump steam supply line open for at least two hours following loss of the normal air supplies will be conducted.

The test was conducted on the accumulators and they held their air supply for the required two hours.

We conclude tha t the licensee's performance of the test is acceptable.

3.2 Additional Short-Tenn Recomendations Recommendation'l The licensee should provide redundant leval indications and low level alarms in the control room for the AFW system primary water supply to allow the operator to anticipate the need to make up water or transfer to an alternate water supply and prevent a low pump suction pressure condition from occurring. The low level setpoint should allow at least 20 minutes for operator action, assuming that the largest capacity AFW pump is operating.

Evaluation 1 In a~ letter dated November 20,1979, t5e licensee stated that the control board presently has a level indicator, a low level alarm and a low-low level alarm for the demineralized water storage tank.

In addition, there is a local gauge available at the tank which measures in feet of water.

Since the low level alarm will alarm at approximately 100,000 gallons and the operator has six (6) hours of water left in the system at that time, the licensee feels that a redundant alarm or indication is unnecessary.

The op~erator will also receive an additional low-level alarm at 10,000 gallons, which provides 30 minutes to line up to another water source.

We conclude that the licensee should provide redundant level indicators and alarms at 20 minutes to alert the operator prior to reaching minimum allowable water level in the tank. We will report resolution of this matter in a supplement to this SER.

Recommendation 2 The licensee should perform a 72-hour endurance test on all AFW system pumps, if such a test or continuous period of operation has not bEld be Following the 72-hour pump run, the pump s accomplished to date.

shut down and cooled down and then restarted and run for one hour. Test acceptance criteria should include demonstrating that the pumps remain within design limits with respect to bearing / bearing oil temperatures and vibration and that pump room. ambient conditions (temperature, humidity) do not exceed environmental qualification limits for safety related equipment in the room.

Evaluation 2 In a letter dated February 20, 1980 the licensee provided the results of their 72-hour endurance test on the AFW system pumps. The results were acceptable in trat the above stated test criteiia were met. The licensee's response to this recommendation is therefore acceptable.

Recommendation 3 The licensee should implement the following requirements as specified in l

Item 2.1.7.b on page A-32 of NUREG-0578:

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. " Safety-grade indication of auxiliary flow to each steam generator should be provided in the :ontrol room.

"The auxiliary feedwater flow instrument channels should be powered from the emergency buses consistent with satisfying the emergency power diversity requirements for the auxiliary feedwater system set forth in Auxiliary Systems Branch Technical Position 10-1 of the Standard Review Plan, Section 10.4.9."

Evaluation 3 In a letter dated November 20, 1979, the licensee stated that control-grade indication of auxiliary flow to each steam generator will be provided in the control room. This equipment was installed in April 1980.

In the long-term, this indication will be provided using safety-grade equipment and will be powered from emergency buses consistent with satisfying the emergency power diversity requirements for Auxiliary Feedwater Systems (AWS) set forth in the staff's Technical Position 10-1 of the Standard Review Plan, Section 10.4.9.

It is the licensee's intention to upgrade to safety grade equipment at the first scheduled outage following receipt of equipment. The licensee indicated that the necessary schematics and design information relating to their proposed upgrading to safety grade was provided to the NRC by letter dated October 17, 1980.

Our evaluation of the licensee's response will be provided in a supplement to this SER.

Recommendation 4 Licensees witn plants which require local manual realignment of valves to corJuct periodic tests on one AFW system train, and there is only one remaining AW train available for operation should propose a Technical Specification to provide that a dedicated individual who is in communication with the control room be stationed at the manual valves. Upon instruction from the control room, this operator would realign the valves in the AFW system train from the test mode to its operational alignment.

Evaluation 4 The licensee stated in a letter dated November 20, 1979 that the Maine Yankee AFWS has three AFW pumps.

Periodic testing of any one of these pumps does not affect the availability of the remaining two pumps.

We, therefore, conclude that this recommendation does not apply to Maine Yankee.

- Long Term Recommendations Recommendation GL-1 For plants with a manual starting AFW system, the licensees should install a system to automatically initiate the AFW system flow. This system and associated automatic initiation signals should be designed and installed to meet safety-grade requirements. Manual AFW system start and control capability should be retained with manual start serving as backup to automatic AFW system initiation.

Evaluation GL-1 In a letter dated October 17,1980 (Reference 17), the licensee provided design information for upgrading the automatic AFWS initiation circuitrb from currently installed control grade (see GS-8) to safety grade.

Manual AFW system start and control capabilities will be retained with manual start serving as backup to automatic AFW system initiation. The licensee has not proposed Technical Specifications requested by our letter dated December 21, 1979. The licensee's intention is to upgrade to safety grade equipment by July 1981.

We will provide an evaluation in a supplement to this SER at a later date.

Recommendation GL-2 Licensees with a~ plant in which all (primary and alternate) water supplies to the AFW system pass through valves in a single flow path should install redundant parallel flow paths (piping and valves).

Licensees with plants in which the primary AFW system water supply passes through valves in a single flow path, but the alternate AFW system water supplies connect to the AFW system pump suction piping downstream of the above valve (s) should install redundant valves parallel to the above valve (s) or provide automatic opening of the valve (s) from the alternate water supply upon~ low pump suction pressure. The licensee should propose Technical Specifications to incorporate appropriate perf adic inspections to verify the valve positions.

Evaluation GL-2 In a letter dated February 15, 1980, the licensee stated that the two water sources provide flow to the pumps through separate flow paths, the valves in the primary flow paths are locked open, and indication and alarms are provided for the primary water source.

We have reviewed the licensee's response and conclude that it is unaccept-a bl e. The licensee has not provided adequate assurance that the st.1gle, locked open valve in the line to the primary water source cannot fail clos ed. We require that the licensee take more positive steps to eliminate this concern such as providing a second parallel valve or automatically tripping the pumps on low suction pressure. We will report the resolution of this matter in a supplement to this SER.

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, In accordance with Recommendation GS-2 under Short Term Recommendations, Maine Yankee committed to include in the plant Technical Specifications the 1

requirement that all manual valves in the AFW system necessary to assure flow from the primary water source to the steam generators be locked in the proper position. A proposed change to Maine Yankee's Technical Specifications which will meet this commitment was submitted on February 22, 1980 (see GS-2). We have reviewed the licensee's response and conclude the j

recommendation has been met and that the Technical Specification revision submitted February 22, 1980 is acceptable.

Recommendation 3 Modify the AFWS design to eliminate the potential for adverse response of the three AFW flow control valves and one of the steam admission valves to the turbine pump due to degradation of power of the Division IV vital bus, e.g. provide service to these valves from different divisions.

Evaluation 3 In a letter dated November 20, 1979, the licensee stated that the AFW system design will be modified to eliminate the potential for adverse response of the three AFW flow control valves and one of the steam admission valves to the turbine pump due to degradation of power to these valves, e.g., provide service to these valves from different vital power supplies. The licensee stated that a design change which addresses this recommendation would be implemented by. March 1,1981.

We find the licensee'c -espon.ie to be acceptable.

Recommendation 4 ihe licensee should evaluate the following concerns:

A pipe break in the auxiliary feedwater system common discharge a.

header could result in the loss of auxiliary feedwater system function even without a postulated single active failure.

The licensee indicated that in such an event the auxiliary feedwater can be manually routed through the main feedwater lines to the stea.a generators.

In the event of a steam or feedwater line break (main or auxiliary) the isolation of one auxiliary feedwater flow path to tne affected steam generator is accomplished manually.

The licensee should evaluate the postulated pipe breaks stated above and (1) determine any AFW system design changes or procedures neces'sary to detect and isolate the break and direct the required feedwater flow to the steam generator (s) be fore they boil dry or (2) describe how the plar, can be brought to a safe shutdown condition by use of other systems wnich would be available following such postulated events.

. Evaluation 4a In a letter dated February 15, 1980, the licensee stated that an evaluation had been performed and provided the following information:

Part a - the staff was concerned with the fact that the three AFW pumps connect to a common discharge header. A failure in the common header could cause all three pumps to be unable to supply flow to the steam generators. An alternate flow path is available to each of the three pumps just upstream of the valve which separates each of the pumps from the common discharge header.

We conclude tha+, part a of the response is acceptable.

Evaluation 4b Part b requests an evaluation of steam line breaks and main and auxiliary feedwater breaks. Adequate instrumentation existed to allow the operator to take the appropriate action.

We conclude that the licensee's response to part b is unacceptable.

It is not clear that the instrumentation required by NUREG-0578 (Automatic initiation of MFW and AFW flow indication) will provide adequate indication. The licensee is requested to more fully respond to the original recommendation. We will provide an evaluation of thic item in a supplement tn this SER.,

D.

Basis for AFW System Flow Requirements In Enclosure 2 to our letter of October 18, 1979, we requested the licensee to provide certain information regarding the design basis for AFWS flow requirements. The licensee ststed in a letter dated

_1979, that the required information will be submitted November 20.

at a la ate. The licensee has [}ot yet supplied this information.

We will provide our evaluation of this matter in a supplement to this SER when the information is available.

E.

New Requirements in our review of the Maine Yankee AFWS as documented in NUREG-0635 and in the preparation of our October 18, 1979 letter to the licensee generic recommenhtion GS-5 and GL-3 were not included. We require the licensee to provide responses to the following:

Recommendation GS-5 The as-built plant should be capable of providin the required AFW flow for at least two hours from one AFW pump train independ9nt of any ac power source.

If manual AW system initiation or flow control is required following a complete loss of ac power, emergency procedures should be established for lanually initiating and controlling the system under these conditions. Since the water for cooling of the lube oil for the turbine-driven pump bearings may be dependent on ac power, design or

.. procedural changes shall be made to eliminate this dependency as soon as practicable. Until this is done, the emergency procedures should provide for an individual to be stationed at the turbine-driven pump in the event of the loss of all ac power to monitor pump bearing and/or lube oil temperatures.

If necessary, this ooerator would operate the turbine-driven pump in an on-off mode until ac power is restored.

Adequate lighting powered by direct current (de) power sources and communications at local stations should also be provided if manual initiation and control of the AFW system is needed (See Recommendation GL-3 for the longer-term resolution of this concern).

Recommendation GL-3 At least one AFW system pump and its associated flow path and essential instrumentation should automatically initiate AFW system flow and be capable of being operated independently of any ac power source for at least two hours. Conversion of de power to ac power is acceptable.

~

Environmental Consideration We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact.

Having made this determination, we have further concluded that the amendaent involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR {51.5(d)(4), thac an environmental impact statement or negative declaration and environ-mental impact appraisal need not be prepared in connection with the issuance of this amendment.

Conclusion We have concluded, based on the considerations discussed above, that:

(1) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the amendment does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in conpliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common oefense and security or to the health and safety of the public.

Date: April 30, 1981

Re ft rOHC es 1.

Letter from W. P. Johnson, Maine Yankee Atomic Power Company to NRC, ti tle:

"Autcmatic Initiation of Auxiliary feedwater Systems," U1Y 80-4, January 9,1980, Letter from E. C.1.'ocd, Maine Yankee Atomic Power Company, to NRC Region 2.

I, title: " Maine Yankee Reportable Occurrence #50-001/017-O', January 30, 1980.

3.

Letter from R. H. Jroce to NRC, title:

" Automatic Initiation of Auxilit.ry Feedur.ter System," UMY CO-19, February 1,1990.

Le tter In c.n D. E. " ody. !4ine Y:nhea Atuaic Fower Co:.any. to NRC, title:

l r I tcc., L N E~er t," r.Y C0-31, Tc5 rut ry 26, l'00.

t...

5.

Letter from R. H. Groce to NRC, title:

" Automatic Initiation of #Jxiliory Fccd ater System (AFUS)," '::1Y 2C-65, April 14,19P.O.

l l

6.

Telecopy from R. H. Groce, Maine Yankee Atomic Power Company, to N. Ua9ner.

l

% C; title:

" Additional Inferration as Pecuested by Conversation on 3/24/80.

l April 15,1980.

7.

Letter from D. E. Vandenburgh, Maine Yankee Atomic Power Company, to NRC; title:

" Revised Steam Line Break Analysis", MiY 80-67, April 17,1930.

l l

8.

Letter from D E. Vandenburgh to NRC; title:

" Response to IE Bulletin l

No. 80-04," WMY 80-72, May 7, 1980.

L 9.

Letter fr:m W. P. Johnson to NRC; title"

" Safety Grade Automatic Initiation i

of the Auxiliary Feedwater System," KMY 80-116, July 25,1980.

10. Letter from D. E. Moody, MYAPC, to NRC; title:

"NRC Requirements for Auxiliary Feedwater Systems at the Maine Yankee Atomic Power Station,"

WMY 79-138, November 20, 1979.

11. Letter from W. P. Johnson, MYAPC, to NRC, title:

" Automatic Initiation l

of Auxiliary Feedwater Systems", WMY 80-4, January 9,1980.

12. Letter from Edwin C. Wood, MYAPC, to NRC, title:

" Maine Yankee Reportable Occurrence #80-001//o1T-o, " January 30, 1980.

j

13. Letter from R. H. Groce, MYACP, to NRC; title:

" Automatic Initiation of l

Auxiliary Feedwater System," WMY 80-19, February 1,1980.

I Letter from D. E. Moody, MYAPC, to NRC; title:

"USNRC Requirements for l

14 Auxiliary Feedwater Systems at the Maine Yankee Atomic Power Station,"

WMY 80-24, February 15, 1980.

15. Letter from D. G. Moody, MYAPC, to NRC; title:

" Endurance Testing of the Auxiliary Feedwater Pumps at Maine Yanked',WMY 80-25, February 20, 1980.

16.

Letter from R. 4. Groce, MYAPC, to NRC; title:

" Automatic initiation of Auxiliary Feedaater System ( AFMS)", WMY 00-65, April 14, 1030.

17. Letter from R. H. Groce to !!CC; title:

" Safety Grade Automatic Initiation of Auxiliary f eed.sater Sy stem ( A:WS)," WMY 20-141, October 17, 1980.

s