ML20038C153
| ML20038C153 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 11/20/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20038C147 | List: |
| References | |
| NUDOCS 8112100164 | |
| Download: ML20038C153 (25) | |
Text
MEGuq(9 UNITED STATES
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- ;3,( (4g' NUCLEAR REGULATORY COMMISSION
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E WASHINGTON, D. C. 20555 kk 4[j f
%w SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 44 TO FACILITY OPERATING LICENSE CONNECTICUT YANKEE ATOMIC POWER COMPANY HADDAM NECK PLANT DOCKET NO. 50-213
1.0 INTRODUCTION AND BACKGROUND
Early into the review of the Th'ree Mile Island No. 2 accident, it became apparent that increased plant safety would result from automatic initiation of auxiliary feedwater system (AFWS) flow. This was short-term recommenda-tion No. 2.1,7a of NUREG-0578.
In our October 30, 1979 letter we provided clarification of the Item 2.1.7a requirements for upgrading the reliability of the auxiliary feedwater system.
By letter dated November 30, 1979, the Connecticut Yankee Atomic Power Company (CYAPCo or the licensee) stated its conclusion pursuant to 10 CFR 50.59 that modification of the AFWS constituted an unreviewed safety question because AFWS flow was not considered in the Haddam Neck Plant main steamline break (MSLB) analyses. CYAPCo's letter contended that the addition of AFW flow during a MSLB would (1) result in a positive reactivity insertion (due to increased cooldown) and a potential return to criticality, and (2) result in increases in the mass and energy released to the containment with the potential for a higher peak containment pressure than indicated in currently approved analyses.
8i12100164 8111207 PDR ADOCK 05000213 P
. Our letters of December 21 and 2?, 1979, address the CYAPCo concern. We-agreed that AFWS flow may adversely affect the MSLB accident and requested a reanalysis of this accident to be submitted for our review and approval prior to_ implementing automatically-initiated AFWS flow. The requested analysis was supplied by'the CYAPCo letter of January 30, 1980. Additional information was prcvided by subsequent letters cited above. This Safety Evaluation will address the effects of automatic initiation of AFWS flow on the likelihood of return to power (Section 2.1) and on the calculated peak containment pressure (Section 2.2) during a postulated main steamline break accident. The implication of automatic AFWS initiation on other postulated accidents will be addressed in Section 2.3.
Our letter of October 11, 1979, presented the NRC staff reliability analysis of the Haddam Neck Plant AFWS and made short-term and long-term recommendations.
CYAPCo's responses to these recommendations were submitted by letters dated December 4, 1979, January 17, 1980, May 19, 1980, June 10, 1980, and September 29, 1980, May 26, 1981, July 22, 1981, August 27, 1981, and September 9, 1981. Our review of this information is presented in Section 2.4 of this Safety Evaluation.
The detailed review of the safety grade instrumentation system required to automatically initiate the AFWS is being reviewed on a post-implementation
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basis. The resultant safety evaluation will be issued at a later time.
- 2.0 DISCUSSION AND EVALUATION 2.1 tELB Accident - Return to Power
'CYAPCo's analysis of the effects of return to power following a MSLB accident is presented in Attachment 1 to their January 30, 1980 letter. CYAPCo states that the' starting analysis ae.sumptions were conservative as follows:
o No delay in delivery of auxiliary feedwater flow to the steam generator was assumed, rather.than a more realistic longer time delay accounting for the delay in AFWS signal initiation and the transient time of the feedwater flow to the steam generator.
o Credit is not taken for main feedwater isolation by the isolation valve.
Instead, the analysis assumes that the feedwater flow follows the control system response which results in a slightly delayed is61ation (for worst case at full power).
o A conservative high auxiliary feedwater flow was assumed to be fed to the damaged steam generator, o Fa'ilure.of une HPSI pump, o Failure of one LPSI pump, o The highest worth CEA is assumed to stick in the fully withdrawn position-for the MSLB cases initiated at full power conditions and in the half-withdrawn position for the accident initiated at zero power.
. o The end of life moderator temperature and Doppler (fuel temperature) coefficient valueswere used since these values result in the greatest positive reactivity change during cooldown.
The analysis assumed that the event is initiated by a circumferential rupture of a 24-inch main steam line at the steam generator nozzle. CYAPCo states that this break is limiting since it results in the greatest rate of tempera-ture reduction in the reactor core region. Reactor trip.and safety injec-tion follow the pipe ruputure. This reanalysis reported in the January 30, 1980 submittal uses the same assumptions and n:ethods as described in a previous licensing submittal for Cycle 8 (Reference 1 and 2) except that it simulates initiation of auxiliary feedwater flow with no delay from initiation of the event. The following two additional model revisions were made for the current analysis:
A.
The model for heat transfer to the auxiliary feedwater after dryout in the broken steam generator assumed that all auxiliary feedwater injected was continuously boiled off and superheated to the primary side temperature, thus conservatively maximizing the primary side cooldown.
B.
Additional nodes were included in the pressurizer model to account for the non-equilibrium effects occuring during refilling of the pressurizer with cold water. The resulting non-equilibrium model predicted a pressure rise and corresponding increase in reactivity whereas the RELAP4 equili-brium model used in previous analyses non-conservatively predicts a pressure decrease during pressurizer refill.
We' conclude that the above two model revisions are conservative for this application and are acceptable.
Although the licensee's analysis methods documented in Reference 1 and 2 were previously reviewed and approved by the NRC for the Cycle 8 operation, we note that the basic computer-code that was used for the Cycle 8 analyses and for the analysis evaluated in this report, RELAP4 MOD 5, has not been reviewed in detail 9enerically. ~ However, based on our. review of the. current _ application of this code to the issue of automatic initi.ation of AFWS during a MSLB, we conclude that the use of th'e code, as modified, is acceptable and that th' re is reasonable e
. assurance.that a more detailed. analytical methods review would not appreciably e
alter our~ conclusions. To provide further confirmation.of our. conclusions re-garding the analytical methods, we plan to perform independent audit calcula-
.tions using an NRC computer code.
The licensee has analyzed four different steam line rupture cases in conjunc-tion with automatic initiation of auxiliary feedwater:
l 1.
Full power, offsite power available, 2.
Full power, coincident loss of offsite power, 1
i 3.
Hot zero power, offsite power available, and 4.
Hot zero power, coincident loss of offsite power.
For all cases, the predicted primary cooldown and reactivity addition was not sufficient to cause a reactor return to power. The analysis indicates that the worst case (least negative reactivity) was for full power with loss of offsite power. We conclude that the licensee's analysis includes a sufficient spectrum of operating conditions.
. The analyses performed for steam line breaks initiated at hot zero power did not assume that the highest worth Control Element Assembly (CEA) was stuck in the fully withdrawn position but rather that it was in the most withdrawn position allowable by plant technical specifications for that operating condition-(rod in half-way position). The licensee has stated f_
in discussions with the NRC staff that it would not be credible to assume the accident to be initiated at the assumed hot zero power conditions with the highest worth CEA fully withdrawn, and that even if that assumption was made, the available shutdown margin is sufficient in this case to still preclude a return to power. Table 1 of Reference 2 shows values of available scram worth for Cycle 8 operation. From this table, it is determined that assuming the maximum worth rod is stuck fully out rather than half-way, the plant's final shutdown margin would be reduced from 1.67% AK/K to 0.004% AK/K (after applying a 10% uncertainty reduction to the licensee's value for additional conservatism). Since the final shutdown margin reported in the current Cycle 9 analyses (Reference 3), is 1.99% AK/K (as compared with 1.67% AK/K for Cycle 8), we concur with the licensee that there would be sufficient shutdown margin for the current cycle even with the rod stuck fully out.
CYAPCo states that single failures concurrent with the MSLB, other than those listed in the assumptions, were not considered since any other postulated failures have not been part of the design basis as described in the FSAR.
The licensee has included in the analysis assumptions of the failure of the non-safety grade MFW isolation valve as well as one HPSI pump. While the licensee has not addressed the failure in the open position of relief or
. steam dump valves located on the intact steam generator, generic analyses of MSLB for similar PWRs have indicated that the worst single failure is the loss of a HPSI as was assumed in the clicensee's present analysis.
The intact steam generators are isolated from the break by the intact main steam isolation valves, the isolation valve in the broken line, and the non-return check valve in the broken line. As noted above, the licensee's analysis assumes failure of the non-safety grade main feedwater isolation valve but takes credit for the eventual main feedwater isolation provided by the control system (also non-safety grade) after turbine trip for the worst case analysis at full power conditions. The assumption is that the MFW valves go to the fully open position briefly until average coolant-temperature falls below 535 F at which point the MFW valves are ramped closed.
Based on our review, which specifically addressed automatic initiation of AFWS, it is our conclusion that sufficient information regarding single failure has been provided and that it has been treated in an acceptable manner in this analysis.
We find that automatic initiation of the AFWS to inject needed makeup water to the steam generators without the need for operator action will improve the nuclear safety of the Haddam Neck Plant. We have reviewed the licensee's submittals addressing automatic initiation of the AFWS and conclude that the proposed method for automatic initiation and supporting analyses are acceptable. The NRC staff plans to perform independent audit calculations to confirm the analytical methods used by the licensee.
1 L
. 2.2 MSLB Accident-Peak Containment Pressure of the CYAPCo's January 30, 1980 letter provides a response to questions posed by our letter of December 21, 1979. Specifically, CYAPCo 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 MSLB, thereby increasing the containment pressure.
The licensee has performed an analysis that demonstrates that with the addition of auxiliary feedwater at the maximum flow condition (1065 gpm)-
containment pressure will remain below the design pressure of 40 psig.
The maximum auxiliary feedwater flow is composed of 666 gpm to the affected steam generator and 133 gpm to each of the intact steam generators. These flows are based on pressure drop calculations with a back pressure of 1 atmosphere in the affected steam generator.
The staff concurs with the licensee's conclusion that the peak containment pressure will remain below the containment design pressure even with the addition of auxiliary feedwater at the maximum flow rate.
2.3 Implication of AFWS Automatic Initiation on Other Postulated Accidents In additico to MSLBs any potential adverse effects on other transients and accidents due to the automatic initiation of AFWS have been considered by
. the staff. For example, in the event of a feedwater line. break, the associated steam generator would be' lost as a heat sink to remove decay heat from the reactor; however, the remaining intact steam generators require in excess of 10 minutes to boil dry, thereby providing sufficient time for the appropriate operation action to isolate the affected steam generator, whether initiation of the AFWS in manual or automatic.
Historically, AFWS has been iniated manually at Haddam Neck as well at several other nuclear power plants. Whenever credit for operator action was required, evaluations demonstrated that the plant was caoable of with -
standing the transient independent of operator action for a minimum of 10 minutes.
It is our conclusion that the automatic initiation of AFWS does not affect the capability of the plant operators to take needed action in these situations.
2.4 CYAPCo Response to NRC Reconmendations In response to our letter of October 11, 1979, CYAPCo provided responses to our short-term and long-term recommendations by letters dated December 4, 1979, January 17, 1980, May 19, 1DE0, June 10, 1980, and September 9, 1980, May 26, 1981, July 22, 1981, August 27, 1981, and September 9, 1981. Our evaluation of these responses is as follows:
2.4.1 Short Term Recommendations Recommendation GS The licensee should propose modifications to the Technical Sepcifications to limit the time period that one AFW system pump and its associated flow '-ain and essential intrumentation can be inoperable. The outage time limit and subsequent action time should be as required in current Technical Specifications; 1.e. /2 hours and 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, respectively.
o
. Evaluation - By letter dated June 1, 1979, the licensee provided proposed revisions to the Technical Specifications. These revisions were incorporated on April 14, 1980, in Amendment No. 34 to the operating license and state that an inoperable auxiliary feedwater pump must be restored to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least hot standby within the next six hours and in hot shutdown within the following six hours. We find the response to this recommendation acceptable.
Recournendation GS The licensee should lock open single valves or multiple valves in series ir the AFW system pump suction piping and lock open other single valves or inultiple valves in series that could inter-rupt all AFW flow. Month'ly inspe'ctions should be perfonned to verify that' these valves ~are locked and in the open position. These inspections
'shoul'd be incorporate'd into the surveillance requirements. of the plant
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Technical Specification's. See Reconnendation GL-2 for 'the Tonger term resolution of this concern.
Evaluation - By letter dated September 9,1981 the licensee stated that the position of 'all valves in the auxiliary feedwater system, i'ncluding the suction valve, is verified monthly as part of the auxiliary feed cumo monthly functional test, SL'R 5.1-13.
The suction valve is maintained in a normally locked open position. We find the licensee's response to this reccmmendation acceptable.
he lonc tem resolution to this recommendaticn is evaluated under GL-2.
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. Recommendation GS Emergency procedures for transferring to alternate sources of AFW supply shoulo be available to the plant operators. These procedures should include criteria to inform the operators when, and in what order, the transfer to alternate water sources should take place.
The following cases should be covered by the procedures:
(1) The case in which the primary water supply is not initially avail-able. 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, (2) The case in which'the primary water supply is being depleted. The procedure for this case should provide for transfer to the alternate
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water sources prior to draining of the primary water supply.
Evaluation - By letter dated July 22, 1981 the licensee stated that procedures for transferring the auxiliary feedwater pump water supply from the primary water supply to the alternate water supply were inplemented on December 19, 1979.
In actuality the primary source of water is always lined up to the suction header. The secondary source of water must be transferred to the primary water source tank before use of secondary source water. The licensee will use the redundant level indicators attached to the primary water source
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tank along with the redundant level alarms to alert the operator to the fact that the water level has dropped to a predetermined level. All suction to the AFW pumps pass through a single locked open valve. Modifications are planned to install a redundant locked open valve around the existing single suction valve. Technical specifications recuire that the level in the primary water source tank te verified once every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
It is considered very un-likely that the primary water supply will ever te initially unavailable. We find the licensee's response to this recommendation acceptable.
. Recomendation-GS The as-built plant should be capable of providing the required AFW flow for at least two hours from one AFW pump train independent of any alternating current power source.
If manual AFW system initiation or flow control is required following a complete loss of alter-nating current power, emergency procedures should be established for manually 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 depe.ndent on alternating current power, design or proce-dural 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 alternating current power to monitor pump bearing and/or lube oil temperatures.
If necessary, this operator would operate the turbine-driven pump in an on-off made until alternating current power is restored. Adequate lighting powered by direct current power sources and comunications at local stations should also be provided if manual initiation and control of the AFW system is needed.
(The longer tenn resolution of this concern is discussed in Recomendation GL-3.)
Evaluation
'By letter dated December 4,1979, the licensee stated that the only alter-nating current dependency was through the need for service water for the AFW turbine-driven pump lube oil coolers. A modification to the AFW system to eliminate this service water dependency has been completed.
Therefore, the turbine-driven AFW pumps are independent of the alternating current electrical system. We conc"lude that the licensee's response to this recomendation is acceptable.
I
. Recommendation GS The itcensee 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:
a.
Procedure should be implemented to require an operator to determine that the AFW system valves are properly aligned and a second operator f.
to independently verify that the valves are properly aligned.
b.
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 the normal flow path from the primary AFW system water source to the steam generators. The flow test should be conducted with AFW system valves in their normal alignment.
Evaluation - By letter dated June 10, 1980, the licensee stated that each auxiliary feedwater train will have an operator verify proper valve alignment following periodic testing or maintenance and a second operator independently verify proper valve alignment. We find the respone to part a. of this recommendation acceptable.
By letter dated July 22, 1981, the licensee stated that by normal operating procedures the turbine driven auxiliary feedwater pumps are used after an l
extended shutdown to verify the normal flow path from the primary AFW source to the steam generators. Normal valve lineup for this test is verified by surveillance procedure. We find the licensee's response to part b. of this recommendation acceptable.
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.14 -
Recommendation GS The licensee should install a system to automatically initiate FW system flow. This system need not be safety-grade; however, in the short-term, it should meet the criteria listed below, which are similar to Item 2.1.7.a of NUREG-0578. For the longer term, the auto-matic initiation signals and circuits should be upgraded to meet safety-grade requirements as indicated in Recommendation GL-5.
(a) The design should provide for the automatic initiation of the auxiliary feedwater system flow.
(b) The automatic initiation signals and circuits should be designed so that a single failure will not result in the loss of auxiliary feedwater system function.
(c) Testability of the initiation signals and circuits shall be a feature of the design.
(d) The initiation signals and circuits should be powered from the emergency buses.
(e) 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.
(f) Any alternating current motor-driven pumps and valves in the auxiliary feedwater system should be included in the automatic actua-tion (simultaneous and/or sequential) of the loads to the emergency buses.
(g) The automatic initiation signals and circuits shall 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 The licensee responded by letter dated December 6. 1979, providing responses to the seven requirements of this recommendation. For the short-term the licensee's response to this recommendation adequately satisfies the " control grade" requirement of this recommendation and is, therefore, acceptable. Refer to GL-5 for long term " safety grade" evaluation of this item.
Short Term Recommendations a.
According to Haddam Neck surveillance procedure No. 5.1-13, the monthly operational check of the auxiliary feedwater pumps is currently performed by closing a manual valve in the common discharge header of both pumps, isolating the normal flow path of the auxiliary feedwater system. A parallel flow path is available by manual opera-tion from the control room through motor operated valve MOV-35. The monthly pump test should be performed by isolating the pumps indi-t vidually such that one pump is always available for normal AFW system l
opera tion. When the system is converted to automatic operation, then l
l the existing procedure will have to be changed to individual pump isolation tests to allow automatic initiation.
b.
According to Haddam Neck surveillance procedure No. 5.1-14, the annual flow capacity test of the AFW pumps is currently performed either at power or in hot standby. During the test temporary piping is con-nected to a valve flange in the common discharge header to divert flow away from the normal flow paths and direct it to the yard sewers via the temporary piping. This diverts flow from both AFW
pumps while the isolation valve in the flange connection is open. This test should not be conducted when the plant is at power since both AFW pumps' availability is affected.
Evaluation - The licensee responded by_ letter dated December 4, 1979, and stated that the surveillance procedure 5.1-13 has been revised to. require that all valves in the normal auxiliary feedwater flow path remain open during the test. The testing of one of the pumps will, therefore, have no effect on the operability of the second pump. We find the response to part a. of this recommendation acceptable.
In a letter dated July 22, 1981, the licensee stated surveillance procedure 5.1-14 prohibits the annual flow capacity testing of the auxiliary feedwater pumps while the plant is at power. We find the licensee's response to this recommendation acceptable.
2.4.2 Additional Short-Term Recommendations Additional Short-Term Recommendation The licensee should provide redundant level 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 alarm setpoint should allow at least 20 minutes for operator action, assuming that the largest capacity AFW pump is operating.
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. Evaluation - By letters dated June 10, 1980 and June 30, 1981 the licensee stated that the currently installed level instrumentation on the primary water supply tank is a pneumatic system with indication and level alarm.
A new redundant electronic level instrumentation system, consisting of a detector, indicator and associated alarms has been installed. Both systems will provide the required 20 minutes of operator action. This new level instrumentation system will be powered by the battery-backed vital cower supply. We find the response to this recommendation acceptable.
Additional Short-Term Recommendation 2 - (This recommendation has been revised from the original recommendation in NUREG-0611) - The licensee should perform a 48-hour enduranca test on all AFW system pumps, if such a test or continuous period of operation has not been accomp!ished to date. Following the 48-hour pump run, the pumps should be shut down and cooled down and then restarted and run for one hour. Test acceptance criteria should include demonstrating that the pumps remain within desigr limits with respect to bearing / bearing oil temperatures and vibration and that pump room ambient conditions (temperature, humidity) do not exceed environ-mental qualification limits for safety-related equipment in the room.
The licensee should provide a summary of the conditions and results of the tests. The summary should include the following: 1) A brief description of the test method (including flow schematic diagram) and host the test was instrumented (i.e where and how bearing temperatures were measured). 2) A discussion of how the test conditions (pump flow, head, speed and steam temperature) compare to design operating conditions.
- 3) Plots of bearing / bearing oil temperature vs. time for each bearing of each AFW pump / driver demonstrating that temperature design limits were
. not exceeded; 4) A plot of pump room ambient temperature and humidity vs.
time demonstrating that the pump room ambient conditions do not exceed environmental qualification limits for safety-related equipment in the room; 5) A statement confirming that the pump vibration did not exceed allowable limits during tests.
Evaluation - By letters dated September 29, 1980, and May 26, 1981, the licensee provided the-results of the 48-hour endurance tests for the turbine driven Aux-iliary Feedwater pumps. The test conditions were in conformance with the pump speed and discharge pressure conditions specified in the recomendation. Data on the bearing oil temperatures were provided for each pump and each turbine bearing and indicated that design limits were not exceeded. Data on pump room ambient temperature and humidity were provided and the licensee indi-cated that these conditions did not exceed the environmental qualification limits for safety-related equipment in the room.
Data were provided on pump and turbine bearing vibrations. The licensee confirmed that the pump and turbine bearing librations did not exceed allow-able limits. Based upon conformance of the test results with the acceptance criteria stated in the recormlendation, we conclude that the licensee's re-sponse to this recommendation is acceptable.
Additional Short-Term Recommendation 3 The licensee should implement the following requirments which are specified by item 2.1.7.b on page A-32 of NUREG-0578:
. " Safety-grade indication of auxiliary feedwater flow to each steam generator shall be provided in the control room. The auxiliary feedwater flow instrument channels shall 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 - The licensee's response was provided in letters dated December 18, 1979, and December 31, 1979. This response will be reviewed on a post-implementation basis. A Safety Evaluation will be issued at a later date.
Additional Short-Term Recommendation 4 Licensees with plants which require a local manual realignment of valves to conduct periodic tests on one AFW system train and which have only one remaining AFW train available for operation, should propose Technical Specifications 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, the operator would realign the valves in the AFW system train from the test mode to its operational alignment.
By letter dated December 4, 1979, the licensee stated that local manual realighment of valves is not required for periodic testing of the auxiliary feedwater system. Therefore, this recommendation is not appli-cable to the Haddam Neck Plant.
. 2.4.3 Long-Term Recommendations Recommendation GL Licensees with' plants in which all (primary and alternate) water supplies to the AFW systems pass through valves in a single flow path should install redundant parallel flow paths (piping and val ves).
.f.
' 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) fran the alternate water supply upon low pump suction pressure.
The licensee should propose Technical Specifications to incorporate appropriate periodic inspections to verify the valve positions.
Evaluation - At the Haddam Neck Plant all suction water to the AFW pumps passes through one valve in a single flow path. By letter dated July 22, 1931 the licensee stated that a bypass valve will be installed around the existing suction line isolation valve. By letter dated September 9,1981 the licensee stated that this valve will be a normally locked open valve. The pcsition of all valves in the auxiliary feedwater system is verified monthly as part of the auxiliary feed pump monthly functional test, SUR 5.l-13.
We find"the response to this recommendation acceptable.
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. Recommendation GL The licensee should' upgrade the AFW system automatic initiation signals and circuits to meet safety-grade requirements.
Evaluation - The licensee provided the safety-grade design for the auto-matic auxiliary feedwater system in a letter dated December 31, 1980.
The review of the response will be performed on a post implementation basis.
A safety evaluation will be issued at a later date.
Long Term Recommendation 3 There is a common crossconnect line with no isolation valves between the two parallel flow paths on the S/G's. A break in this section cannot be isolated in the present design and the total system would be unavailable. It is recommended that some modificaticns be made (such as isolation valves) to provide isolation when necesn ry and assure a means of supplying AFW flow following isolation of such a break. The licensee has begun design plans to add a motor driven pump to the system.
The licensee should introduce ths flow from this third pump in such a manner that a break in this crossconnect line will not result in the loss of all pumps. Also the licensee should 1) install the third pump with appropriate valves in the pump discharge line connections to rxet the l
high energy line break criteria in SRP 10.4.9 and Branch Technical Position ASB 10-1; namely, to maintain the capability to supply the required AFW flow to the steam generators with a postulated pipe break anywhere in the AFW pump discharge lines plus a single active failure, or 2) describe how the plant can be brought to a safe shutdown condition by use of other available systens following such a postulated event.
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, Evaluation - By letters dated December 4, 1979, and July 22, 1981, the licensee stated that a normally open air operated isolation valve will be installed in the common corssconnect line between the tow turbine driven AFW pumps.
Manual control of this valve will be provided -in the control' room.
This valve will be capable of local manual operation if required. The
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intended modification will permit isolation of the two AFWyrain in the 1
C event of a break in the common crossconnect line.
By letter dated December 4,1979, the licensee stated that the third motor' o
driven pump will only be aligned temporarily using a pipe spool piece,
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during startups to supply feedwater to the steam generators. m By letter dated July 1, 1981, the staff requested that the licensee upgrade this pump to meet the power diversity position as contained in Branch Technical Position ASB 10-1.
By letter dated August 27, 1981, the licensee provided additional information. We will report resolution of this matter.,in as 1
supplement to this SER.
3, '
w, 2.4.4 Considerations Based on the Systematic Evaluation Program 1.
The AFW system itself is not designed to withstand a passive failure'at i
all points within the system. A pipe break in a normally, pressurized l
portion of the AFW system can be isolated by operation of manual, valves l
outside the control room. An alternate flow path to all four S/G's would c
be available following such isolation. The motor driven' main feedwater pumps may also be available in this event since no transient should
(
i result to cause a less of non-vital power. For the same reasons,.the main feed pumps may also be available following a break'in any portion of the AFW system that is not normally pressurized elen though the AFW sys. tem C.
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' break and sing 1e acfivh' failure). This review is being conducted as a part s
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3 of the Systematic Evaluation Program (SEP).
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The Shste'matN[ valuation Program (SEP) will re-evaluate the plant
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internally and externally generated missiles, pipe whip and jet impingement and seismic design requirements, tornadoes, floods and m(
failure of ronessential systens.
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the possible need for automatic tennination of feedwater flow to a glepressurized -
en'erator and providing flow to the intact steam is,,
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..as isfeccomplished by the control room operator.
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s The above two items are under review in the Systematic Evaluation b'
Program.
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(,+1 2.4.5 - Basis for Auxiliary Feedwater Flow Rec,uirements We required that the licensee provide AFW system flow design basis information as applicable to the design basis transients and accident conditions. The licensee's response was provided in a letter dated May 19, 1980. We have reviewed the licensee's response to this recomendation and conclude that the licensee's flow design bases are acceptable.
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3.0 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 amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 151.5(d)(4), that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
4.0 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 compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
5.0 REFERENCES
1.
Letter from W. G. Counsil to D. L. Zieraann,.Haddam Neck Plant, Emergency -
Power Systems, September 22, 1978.
2.
Letter from W. G. Counsil to D. L. Ziemann, Haddam Neck Plant,. Emergency Power Systems, October 20, 1978.
3.
Letter from W. G. Counsil to D. L. Ziemann, Automatic Initiation of Auxiliary Feedwater, January 30, 1980.
Date: November 20, 1981 P
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