ML18045A448

Responds to IE Bulletin 80-12 Re Decay Heat Removal Sys. Reviews Incident Circumstances & Event Sequence,Plant Decay Heat Removal Degradation Events,Hardware Capability & Adequacy of Safeguard Procedures Re Loss Events

ML18045A448
Person / Time
Site:	Palisades
Issue date:	08/01/1980
From:	Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-80-12, NUDOCS 8008060296
Download: ML18045A448 (8)

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consumers Power company General Offices: 212 West Michigan Avenue, Jackson, Michigan 49201 **Area Code 517 788-0550 August 1, 1980 Mr James G Keppler Office of Inspection and Enforcement Region III U S Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 DOCKET 50-255 - LICENSE DPR PALISADES PLANT - RESPONSE TO IE BULLETIN 80 DECAY HEAT REMOVAL SYSTEM Consumers Power Company was requested by IE Bulletin 80-12 (Decay Heat Removal (DHR) System) dated May 9, 1980, to review our Palisades Plant DHR System.

Our response is as follows:

Item 1 Review the circumstances and sequence of events at Davis-Besse.

Response to Item 1 The circumstances and sequence of events experienced at Davis-Besse during the

, DHR loss incident have been examined for relevance to the Palisades Plant design.

The examination included a revi.ew of the *electrical distribution single line diagram and the Safety Injection System P&ID for Davis-Besse.

Review of the incident scenario sequence of events permitted the identification of key problem areas which needed to be investigated in regard to the Palisades Plant.

These areas include the Palisades DHR System mechanical design; Engineered Safety Feature Actuation System design; and, administrative controls on shutdown electrical line-ups and maintenance operations.

The results of the investigation are presented in Item 3.

Item 2 Review your facility for all DHR degradation events experienced, especially for eyents similar to the Davis-Besse incident.

Response to Item 2 There have not been any DHR loss events experienced at the Palisades Plant result-ing from the same series of initiating events as experienced at Davis-Besse.

Pali-sades operational history has been reviewed for all loss of DHR events.

The only loss of the Shutdown Cooling System (SDC) occurred while the reactor was in a Cold AUG 5

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• Mr James G Keppler Palisades Plant August 1, 1980 2

Shutdown condition.

Water in the CV-3025 caused the valve to fail operation of the air compressors problem areas identified in Item air line to the SDC heat exchanger outlet valve closed.

This incident was attributed to improper I

and did not constitute conce~n in any of the

1.

Item 3 Review the hardware capability of your facility to prevent DHR loss events, includ-ing equipment.redundancy, diversity, power source reliability~ instrumentation and control reliability, and overall reliability during.the refueling and Cold Shutdown modes of operation.

i Response to Item 3 T'.ae hardware capab,ilities of the Palisades Plant design were reviewed for adequacy I

in preventing DHR system loss events, particularly during theiCold Shutdown and Refueling modes of operation.

The sequence of events at Davis-Besse were used as the framework for performing the review.

The findings are as; follows:

A.

~

Power Sdurces I

1.

Two channels of the Reactor Protective System (RPS) ~d Engineered Safety Feature Actuation System (SFA) were powered from a single source at Davis-Besse.

At Palisades, each channel is powered from its own source.

2.

Administrative controls are used to maintain the electrical system in a highly reliable lineup during all modes of operation *. ! The lineup is such that* no single fault in the electrical distribution system will cause a loss of power to two of the four instrument buses that supply input signals to the SFA System.

B.

Logic and System Initiation

1. Davis-Besse has a two out of four logic scheme for a kPs and SFA System.

initiation.

Loss of power to two channels of the SFA! System results in an initiation cf:

a.

containment isolation

b.

high-pressure injection

c.

low-pressure injection

d.

containment spray

e.

recirculation

2.

The Palisades Plant also has two out of four logic and* loss of power to two channels will cause an initiation of:

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a.

containment isolation

b.

safety injection

c.

containment spray

d.

recirculation The valve line-up during SDC adds protection *against,a loss of DHR should a loss of power occur (refer to Item C-2b).

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Mr James G Keppler Palisades Plant August 1, 1980 I

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c.

D.

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Loss of*Power i

l. The actuation of the SFA System at Davis-Besse due to a loss of power to two channels resulted in:

2.

a.

isolation of the operating LPSI pump suction from the hot leg

b.

shifting suction to the borated water storage ta.Oki

c.

shifting suction to the dry containment sump; ther~by airbind-ing the pump (see Figure 1).

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Should the actuation of the SFA System occur at the Pah.isades Plant due to a loss of power to two channels:

[

a. the Containment Isolation Signal does )not cause an isolation of the hot leg from either LPSI pump I

b.

Safety Injection Actuation results in a signal beiJng sent to start LPSI pumps P67A and P67B and open the Safety Injedtion and Refueling Water Tank (SIRWT) isolation valves CV-3031 and CV-3057.

Manually closed valves V-3189 and V-3198 isolate the LPSI ~umps' suct~ons from the SIRWT.

The result is continued operatiori of the LPSI pump.

c.

recirculation actuation sends a signal to secure the LPSI pumps, I

isolates the SIRWT by closing CV-3031 and CV-3057~ and opens the containment sump suction valves CV-3029 and CV-3030.

Manually closed valves CV-3189 and CV-3198 isolate the.pumps'. suctions from the dry containment sump.

Check valves in the piping connecting the SIRWT and sump prevent a* gravity feed flow toithe sump during the switch from receipt.of the Safety Injection Actuation Signal (SIAS) and the Recirculation Actuation Signal (RAS) (as had occurred at Davis-Besse).

At this point, recovery require~ a restoration of I

lost power, and either clearing the RAS or overriding the RAS on a component level by restarting the LPSI pump in th~ SDC loop being used for DHR (see Figure 2)

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Redundancy and Diversity Review of the Palisades Plant DHR I

1. Redundancy -*The operation of one LPSI pump and SDC heat exchanger (along with the associated valving and piping) will remove dbcay heat during refueling. Technical Specifications require that the:se components be available as a minimum condition for operation.

Another LPSI pump and SDC heat exchanger (and associated valving and piping 1

) constitute the degree of equipment redundancy available for cooldown and refueling I

purposes.

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2.

Diversity - The diverse methods available for removaJl of decay heat depend on the operational mode.

i.

a.

a HPSI p~p may be used to circulate the primary !coolant through the SDC heat exchanger during cold shutdown and i-efueling

b. the Fuel Pool Cooling System may be used to remove decay heat (see plant procedure ONP#l7, Loss of Shutdown Cooling)

c. the steam generators can be used to maintain the ! plant in a Hot Shutdown condition until the SDC is operable; ifithe PCS pressure boundary is intact I

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Mr James G Keppler Pali sades Plant August l, 1980 4

d. the containment spray pumps, the charging pumps, the HPSI pumps or the LPSI pumps may be used to match boil-off by delivering water from SIRWT to the core if the PCS pressure bounda.ry:is not intact.

E.

Power Source Arrangement The proper arrangement of power to the SFA System at the Palisades Plant has the four (4) channels of the SFA System powered from four separate sources during all operational modes.

A two out of four abnormal signal actuates the SFA System.

Consequently, failure of source power to a single channel cannot initiate the SFA System.

Item 4 Analyze your procedures for adequacy of safeguarding aginst loss of redundancy and diversity of DHR capability.

Response to Item 4 The General Operating Procedure applicable for plant cooldowns from the Hot Shut-down mode and the System Operating Procedure dealing with the operation of the SDC System were reviewed for adequacy in safeguarding the plant against a loss of redundancy and diversity during cold shutdown and refueling.

These procedures provide sufficient guidance.

_I_~em 5 Analyze your procedure for adequacy of responding to DHR loss events.

Special emphasis should be placed upon response when maintenance or refueling activities degrade the DHR capability.

Response to Item 5 The procedure for recovery from a loss of the SDC System was analyzed for adequacy.

This procedure was found to be complete in its coverage of redundant and diverse alternatives for DHR in response to the specified SDC System failures.

Should inadequate administrative controls be utilized in the authorization of maintenance, the ability to recover as delineated in this procedure could be compromised.

Item -6 Until further notice or until Technical Specifications are revised to resolve the issues of this Bulletin, you should:

A.

Implement as soon as practicabl administrative controls to assure that redundant or diverse DHR methods are available during all modes of plant operation.

(Note:

When in a refueling mode with water in the refueling cavity and the head removed, an acceptable means could include one DHR train and a readily accessible source of borated water to replenish any loss of inventory that might occur subsequent to the loss of the available DHR train.)

B.

Implement administrative controls as soon as practicable, for those cases where single failures or other actions can result in only, one DHR train being avail-able, requiring an alternate means of DHR or expediting.the restoration of the

Mr James G Keppler Palisades Plant August 1, 1980 lost train or method.

Response to Item 6 The Palisades Plant presently has adequate administrative controls to assure redundant or diverse DHR methods as well as for the single failures that may result in only one DHR train being available.

Item 7 5

Report to the NRC within 30 days of the date of this Bulletin the results of the above reviews and analyses describing:

A.

Changes to procedures (eg, emergency, operational, administrative, maintenance, refueling) made or initiated as a result of your reriews and analyses, including the scheduled or actual dates of accomplishment.

(Note:

NRC suggests that you consider the following:

(1) limiting maintenance activities to assure redundan-cy or diversity and integrity of DHR capability, and (2) bypassing or disabling where applicable, automatic actuation of ECCS recirculation in addition to dis-abling High Pressure Injection and Containment Spray preparatory to the Cold Shutdown or Refueling mode.)

B.

The safeguards at your facility(ies) against DHR degradation, including your assessment of their adequacy.

Response to <Item 7 The review of the DHR system has not resulted in any need for procedural changes or modifications.

The description of safeguards against the DHR degradation are discuss~d in Item 3 of this response.

David P Hoffman (Signed)

David P Hoffman Nuclear Licensing Administrator CC Director, Office of Nuclear Reactor Regulation Director, Office of Inspection and Enforcement NRC Resident Inspector - Palisades Attachment (Figure 1 & 2)

CONSUMERS POWER COMP ANY Palisades Plant IE Bulletin 80-12 Docket 50-255 License DPR-20 At the request of the Commission and pursuant to the Atomic Energy Act of 1954*

and the Energy Reorganization Act of 1974, as amended, and the Commission's Rules and Regulations thereunder, Consumers Power Company submits our response to IE Bulletin 80-12, dated May 9, 1980, entitled, "Decay Heat Removal (DHR)

System".

Consumers Power Company's response is dated August 1, 1980.

COliSUMERS POWER COMPANY By R C Youngdahl (Signed)

R C Youngdahl, Executive Vice President Sworn and subscribed to before me this 1st day of August, 1980.

Linda K Carstens (Signed)

Linda K Carstens, Notary Public Jac;Jtson County, Michigan My commission expires June 10,, 1981 (SEAL)

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SUMP SUMP

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FIGURE 1 DAVIS-BESSE BEFORE AFTER BWST BWST

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SUMP V-3030 V-3016 SUMP V-30 30 V-3166 V-3016 I

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V-3029 V-3181 V-3190 V-3199 LPSI P-67A V-3029 V-3190 V-3199 LPSI P-67A FIGURE 2 PP.LlSACE£'.

BEFORE V-3198 LPSI P-678 AFTER V-3198 LPSI P-678 V-3057 V-3189 V-3240 '

V-3057 SRIWT SIRWT w

V-3031 V-3031