ML19242A857
| ML19242A857 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 06/26/1979 |
| From: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| NUDOCS 7908060477 | |
| Download: ML19242A857 (7) | |
Text
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CONNECTICUT YANKEE AT O M IC POWER COMPANY BERLIN. CONNECTICUT P O BOX 270 H A RTFO R D. CON N ECTICUT 06101 L
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203-665 6911 June 26, 1979 Docket No. 50-213 Mr. Boyce II. Grier Director, Region 1 Offica of Inspection and Enforcement U.
S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, n 19406
Reference:
(1)
W.
G. Counsil letters to B. H. Grier, dated April 24, May 14, and May 18, 1979.
Dear Mr. Grier:
lladdam Neck Plant Supplementary Information I&E Bulletin 79-06A, Rev. 1 In Reference (1), Connecticat Yankee Atomic Power Company (C(APCO) submitted its initial and supplementar y responses to the various items discussed in I&F Bulletin 79-06A, Rev. 1.
During the course of oar continuing evaluation of those areas addressed by the ISE Bulletin and, based on discussions with the NRC Staff, additional percinent and clarifying information has been developed by CYAPCO.
This information is hereby submitted to supplement our earlier responses.
Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY
/
l (&ds W. G. Counsil Vice President At tachment cc: Office of Inspection and Enforcement Division of Reactor Operations Inspections U.
S. Nuclear Regulatory Commission Washington, D. C.
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DOCKET NO. 50-2i3 ATTACHMENT HADDAM NECK PLANT SUPPLEMENTARY RESPONSES TO I&E BULLETIN 79-06A, REV.1 JUNE, 1979
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HADDAM NECK PLANT DOCKET No. 50-213 SUPPLEMENTARY RESPONSES TO I&E BULLETIN 79-06A, REV.1 During the course of our continuing evaluation of the areas identified in I&E Balletin 79-06 and, based on our discussions with the NRC Staf f, additional pertineut information has been developed by CYAPCO. The fo11 ewing information is submitted, with the numbers corresponding to the Bulletin items, to upple-ment our eaclier responses, dated April 24, 1979 and May 18, 1979.
CYAPCO would like to note that r.he information described below is subject to change based upon our review of the forthcoming results of the generic effort currently being performed by the Westinghouse Electric Cerporation.
Item 2a The applicable emergency procedures have been reviewed thoroughly in light of the TML incident to include steps that specifically warn of the potential for void formation and the instrumentation available far recognizing or identifying the indications for potential or actual voiding, that is, the possibility for void formation exists in the Reactor Coolant Systems whenever pressure is equal to or less than saturation pressure. An example of the procedural wording is given below.
" Verify that the reactor and turbine Inve tripped.
Core cooling has initiated and that all core cooling equipment is operating properly.
Operating reactor coolant pumps can remain in service until RCS pressure is 325 psig.
If all reactor r elant pumps must be secured, monitor the degree of subcooling in core by comparing core outlet temperature uith saturation temperature for pressurizer pressure.
Use the s.uration curve (At tac hment A to this procedure) and maintain pressure in the reactor core equal to or greater than
" saturation curve F 50 F safety band".
Establish a flow producing a core AT greater than 10 F by steam dump / atmospheric vent operation in conjunction with auxiliary f eedwater flow. Monitor the potential for voiding by verifying a stable or decreasing core AT of Jess than 50 F.
Other instrumentation which can be used to monitor core conditions both during natural or forced circulation are listed in Attachment B.
If voiding occurs, reestablish pressurizer pressare and level using pressurizer heaters, charging pumps, and/or HPSI, as needed and isolate break if possible."
Item 2b The applicable emergency procedures have been further reviewed and revised to specifically address operator actions based upon the indications described in Item 2a, for terminating conditions leading to void formation. An example of the procedural wording is given below.
" Regulate feedwater additions to the steam generators as necessary to maintain heat sink. Maintain water level between 50% and 95% on the wide range level indication.
If normal station power has been lost, operate the steam driven auxiliary feed pumps.
Dump steam to condenser until overriden by low condenser (if loss of offsite power) vacuum.
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Caution:
Be careful not to over feed the steam generator and cause a further RCS pressure reduction."
Itan 2c The applicable procedures have been revised to provide guidance to the operators for enhancing core cooling should void formation in the primary system actually occur, as noted in the above responses.
Item 4 A method has been developed which enables an opert ro ' to manually initiate co ntainment isolation f rom the Control Room upon a,comatic initiation of safety inj ec tio n.
Detailed steps have been included in the applicable emergency procedures for implementing this method.
The reactor coolant pumps could be operated under a containment isolation condition for a short period of time.
For periods of operation longer than just a few minutes, cooling water must be reestablished for bearing cooling, otherwise, this could result in severe danage to the pump.
If cooling water is not rcestablished, bearings could fail resulting in excessive vibration lea '!ng to seal failure and excessive reactor coolant leakage to the containment.
L.ls condition would require isolation of the af fected loop and loss of that particu-lar steam generator as a heat sink for decay heat removal. Cooling water flow to the reactor coolant pumps bearing coolers could be reestablished by resetting and blocking open the trip relay for the containment isolation trip valve (TV-1411) on this system.
This function would be performed by the auxiliary operator locally in the primary auxiliary building, upon instruction f rom the Control Room.
Item 7a Steps have been included in the applicable procedures instructing the operators not to override automatic actions of engineered safety features unless initiation is, in fact, spurious or continued operation of those features would result in unsafe plant conditions. An example of the procedural wording is as follows :
"Do not override automatic actions of engineered safety features unless continued operation of engineered safety features will result in unsafe plant co nd it ions. "
Licensed operators have been instructed to comply with the above direction.
Training on all revised emergency procedures will be completed by June 30, 1979.
The above direction will also be included in the Licensed Opcrator Training and Requalification Program by June 30, 1979.
Itnm 7b In reviewing this I&E Bulletin item, CYAPCO recognized the NRC Staf f position yet needed to factor into the response the fact that the charging and residual heat removal pumps at the Ibddam Neck ' Plant function as part of the ECCS.
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Therefore, in recognition of this function and previous discuse tons with the NRC Stafi regarding the ability to provide core cooling during the transition pha ses (i.e.,
iniection to recirculation) of an incident, the following steps have been included in the applicable proceduren-
" Safety injection can be secureu only when:
Both low pressure safety injection pumps or a combination of low pressure safety injection pumps and residual heat remosal pumps are in operation and flowing for twenty (20) ulinutes or longer; at a rate which would ensure stable plant behavior; or The llPSI pumps or a combination of IIPSI pumps and charging pumps have been in operation for twenty (20) minutes, and all hot and cold Aeg temperatures are at least fifty (50) degrees below the saturation temperature for the existing RCS pressure.
If fif ty (50) degrees subcooling nnot be maintained after HPSI and/or charging cutoff, the HPSI and, charring shall be reactiviated. The degree of subcooling beyond fif ty (50) degrees and the length of time IIPSI and/or charging is in operation shall be limited by the pressure /
temperature considerations for the vessel integrity."
The procedure also includes provisions which give consideration to the other points raised by CYAPCO in our April 24, 1979 response.
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e Item 8 Applicable maintenance and operating procedures have beca reviewed and revised to provide for proper positions and alignment checks of safety related valves following maintenance activities associated with saf ety related components and/or systems.
Periodic surveillance of all safety related valves, except those included on the " Locked Valve List", will be performed monthly. The
" Locked Valve List" has been formalized as a plant procedure and requires a check of all locked valves prior to any startup from a cold shutdown (Mod e 5) co nd it io n.
Itc d CYAPCO has reevaluated the capability for inadvertently transf e. ring radioactive mat alials from inside to outside containment through the various systems, lis: cd in cur April 24, 1979 response.
As noted in the May 18, 1979 response, four penetration (lines) are normall y isolated by closed manual shutoff valves. They would be open only for sampling operations involving sampling ef fluent from their particular sources.
Because they are normally isolated, they are fitted with single trip valves for redun-dant isolation during high containment pressure conditions.
Instructions have been included in the applicable emergency procedures to place the control switcher for these four trip valves TV-950, 945, 960, and 265 in the close position to preclude automatic opening if resett of h2gh containment pressure (HCP) relays were to occur.
Those lines which are isolated by high containment pressure oth4 han the four above are fitted with two redundant trip valves, one of which t ne reset manually following reset of the high containment pressure relays.
To prevent inadvertent releases fo11 ewing reset of HCP, a step has beea included in the applicable emergency procedures to preclude resetting of the individual trip valves which luve been automatically or manually isolated.
Prior to reset, it must be verified that the line could perforn its intended function and that it would not constitute a significant releasr path to the environment.
For example, Step 1.4 of E0P 3.1-4, Loss of Coclant, states "Before opening any valves that have been closed by HCP initiation, verif y by available instrumentation that the lines love integrity: would perform their intended f unction or would not cause a significant release path."
Containment sump pumps are evered additionally by placing the control switches in the trip pullout po s it io n. This maintains the discharge valves in closed position.
Item 10a Operations Department Instruction ODI-39 has been revised to include testing of saf ety related systems prior to removal and following the return to service of redundant systems.
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Item 12 Existing plant procedure NOP 2.13-4, Venting of Ilydrogen f rom the Containment Following A Loss of Coolant Acc id ent, In c been reviewed and found adequate for control of hydrogen concentrations in the containment.
Existing plant procedure NOP 2.14-9, Degassing; of Reactor Coolant System, as well as supporting procedures, have been reviewed. A new procedure for controlling hydrogen gas accumulation in the reactor coolant system during off-normal situations will be implemented by August 1, 1979, h}b
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