ML20137Z497

Suppl 2 to Safety Evaluation Re Submittal 1 to Rev 3 of CEN-152, C-E Emergency Procedure Guidelines. Submittal Acceptable for Implementation & Will Provide Improved Emergency Procedure Development Guidance

ML20137Z497
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Issue date:	12/02/1985
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,. SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR COMBUSTION ENGINEERING ,

EMERGENCY PROCEDURE GUIDELINES

1.0 INTRODUCTION

In the Safety Evaluation Report (SER) of July 29, 1983, covering Revision 01 of CEN-152, " Combustion Engineering Emergency Procedure Guidelines (EPGs)," the staff identified a number of items that required further consideration by the Combustion Engineering Dwners Group (CE0G).

By letters dated May 8, 1984 and November 26, 1984, the CE0G transmitted Revision 02 to CEN-152, which addressed some of the items identified in our July 29, 1983 SER. The results of the staff's review of these submittals was provided in Supplement 1 to the SER for CEN-152, dated April 16, 1985.

A new Submittal 1 of Revision 03 to CEN-152 was. transmitted to us by letter dated July 1, 1985. Submittal 1, Revision 03 guidelines proposed changes which addressed the following July 29, 1983 SER items which were not addressed in the staff's Supplement 1 to the SER (each item number is identified by the paragraph number from the July 29,1983SER):

A. 3.4.2.3.a - Containment Hydrogen Control in Loss-of-Coolant Accident (LOCA) Optimum Recovery Guideline (ORG)

B .- 3.4.2.3.b - Reactuation of the Containment Spray System in LOCA ORG C. 3.4.2.3.c - Selection of Hydrogen Control Actions in LOCA ORG D. 3.4.2.3.d - Instructions for Operation of Hydrogen Recombiners in LOCA ORG

. E. 3.4.2.3.f - Containment and Reactor Coolant Pump (RCP) Cooling Capability in LOCA ORG F. 3.5.2.12.a - Containment Hydrogen Control in Steam Generator Tube Rupture (SGTR) ORG G. 3.5.2.12.b - Reactuation of the Containnent Spray System in SGTR ORG H. 3.5.2.12.c - Selection of Hydrogen Control Actions in SGTR ORG I. 3.5.2.12.d - Instructions for Operation of Hydrogen Recombiners in SGTR ORG J. 3.6.2.7.a - Containment Hydrogen Control in Excess Steam Demand *

(ESD) ORG K. 3.6.2.7.b - Reactuation of Containment Spray System in ESD ORG

• Excess Steam Demand previously entitled Steam Line Break.

8512110317 851202 DR TOPRP EMVC-E

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L. 3.6.2.7.c - Selection of Hydrogen Control Actions in ESD ORG M. 3.6.2.7.d - Instructions for Operation of Hydrogen Recombiners in ESD ORG N. 3.6.2.7.f - Containment and RCP Cooling Capability in ESD ORG

0. 3.7.2.5.a - Containment Hydrogen Control in Loss of Feedwater (LOF)

% ORG P. 3.7.2.5.b - Reactuation of Containment Spray System in LOF ORG Q. 3.7.2.5.c - Selection of Hydrogen Control Actions in LOF ORG R. 3.7.2.5.d - Instructions for Operation of Hydrogen Recombiners in LOF ORG S. 3.9.1.2.4 - Consistency of Cont'ainment Pressure Parameter in .

Functional Recovery Guidelines (FRGs)

T. 3.9.6.2 - Containment Environment Control in FRGs U. 3.9.7.2.1 - Long Term Operator Actions in ORGs and FRGs The staff has reviewed the technical changes incorporated in Submittal 1, Revision 03 of CEN-152, and the evaluation of these changes is contained in Section 2.0. Bracketed [] items signify that plant-specific confirmation is expected by each utility.

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2.0 EVALUATION 2.1 Item 3.4.2.3.a and Item 3.6.2.7.a - Containment Hydrogen Control in LOCA and ESD ORGs In the July 29, 1983 generic SER, the staff requested that instructions be provided in the LOCA and ESD guidelines to address the potential for a buildup of containment hydrogen concentration and/or the need to preserve containment integrity by venting. The generic SER indicated that since venting may release large quantities of radioactive material, this action should be based upon a realistic appraisal of containment capability and purge / vent system operability under accident conditions.

It was also recommended that the guidance specify setpoints for operator actions.

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Submittal 1 of Revision 03 has added guidance to CEN-152 regarding containment hydrogen control in the LOCA and ESD ORGs. To ensure that the containment combustible gas control safety function is satisfied, hydrogen monitors are ) laced in service. If the containment hydrogen concentration exceeds :0.5%) or if containment spray has been actuated, then the' hydrogen recombiners are to be energized. Operation of the hydrogen recombiners is to be terminated when the hydrogen concentration  ;

'is less than [0.5%]. This concentration is typically the minimum measurable concentration when considering instrumentation error.

Energizing the hydrogen recombiners anytime containment spray is actuated is intended to prevent the potential buildup of hydrogen in the containment from the spray solution corroding aluminum and zinc materials.

The Safety Function Status Check (SFSC) for the Containment Combustible Gas Control Safety Check in the LOCA and ESD ORGs consists of the following acceptance criteria: ,

a) Hydrogen concentration less than [0.5%]

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OR b) [All available hydrogen recombiners energized]

AND c) Hydrogen concentration less than [4%].

If the acceptance criteria are not met, then the operator is to transfer

- to the Containment Combustible Gas Control FRG. Since the acceptance criteria logic can be interpreted two ways and could be confusing to the operator, the staff has requested that the logic be clarified.

In the LOCA guideline, the hydrogen purge system is started only after

the appropriate technical group (i.e., Plant Technical Support Center) e has reviewed and recomended its use. There is no specific criteria i provided in the guidelines on when to purge. Prior to the use of the

(' hydrogen purge system, the iodine removal system is to be operated to decrease airborne radiation level in the containment. This action will help to reduce the activity released to the environment. The LOCA guideline points out that the following factors should be considered l when purging: containment atmosphere radiation level, containment hydrogen concentration, rate of increase in the hydrogen concentration, time required to make hydrogen recombiners available, expected effects of a hydrogen burn, and any plant-specific requirements for purging containment atmosphere. Operation of the hydrogen purge system is terminatedwhenthehydrogenconcentrationhasdecreasedbelow[3.5%).

Unnecessary offsite dose will be avoided by terminating the purge when the hydrogen concentration is slightly below the flammable limit (4%).

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4 The staff requests that the guidelines include more definitive criteria for purging of the containment for hydrogen control. Many variables should be considered in the development of a criteria; these include plant-specific considerations (site, containment ultimate pressure ~

capacity, purgedependent accident-scenario /ventvalveoperability,(et:),aswellas parameters H,3 concentration and rate of increase, recombiner operability, source term inside containment, etc.).

A key consideration in the decision of whether to purge is the containment pressure capacity. A strategy to purge for hydrogen control (to prevent containment overpressure failure due to a hydrogen burn) might be formulated generically based on the premise that all containments can be pressurized to some multiple of their design pressure. The matter of purge / vent valve operability, and the capability to reclose.under accident conditions needs to be addressed by licensees on a plant-specific basis.

A second key consideration governing purging is the source term inside containment. Recent work indicates that accident source terms will be substantially less than those previously estimated in WASH-1400.

- Continuing work in this area may provide additional support for use of purging in lieu of pemitting flamable mixtures to form in containment.

On balance, the number of and uncertainties in the variables which enter into a decision whether to purge for hydrogen control are sufficiently large so that the purge criteria should not be based solel value of a single parameter (i.e., hydrogen concentration)y applicable on atosingle all plants. Rather, the decision should be made on a plant-specific basis by carefully considering all relevant plant parameters beforehand, developing plant-specific criteria under which purging for hydrogen control will be perfomed, and incorporating these criteria in the plant-specific emergency procedures. This would facilitate the decision by the Technical Support Center during an accident. The methodology for developing the criteria should be discussed in detail in the CE EPGs; however, the supporting plant analyses and plant-specific implementation would be perfomed by each utility. The objective of the purge criteria should be to call for purging only under those conditions for which hydrogen combustion poses an imediate threat to containment structural integrity or equipment survivability.

The CEOG has indicated that the ESD event is not expected to produce

.large amounts of hydrogen and iodine in the containment atmosphere.

Therefore, guidance on the use of the hydrogen purge system and the use of the iodine removal system has not been provided in the ESD ORG.

i However, as indicated previously, the guideline provides instructions to l

transfer to the Containment Combustible Gas Control FRG if the hydrogen concentration is not less than 4% for an ESD event. This strategy is acceptable to the staff.

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, The staff has reviewed the changes to the LOCA and ESD ORGs regarding Containment Hydrogen Control and concludes:

A. that the LOCA ORG should be expanded to include criteria for purging the containment for hydrogen control, and B. that the LOCA and ESD ORGs SFSC acceptance criteria should be written on a_ plant-specific basis by considering all relevent plant parameters instead of relying only on hydrogen concentration and incorporating these criteria in the emergency procedures.

i Since the current LOCA and ESD ORG modifications are an improvement over the previous Revision 02 of the EPGs (in the area of hydrogen control),

the above residual issues can be addressed in the long term.

Therefore, interim implementation is acceptable. We will address resolution of the preceding items in a future SER supplement.

2.2. Item 3.4.2.3.b and Item 3.6.2.7.b - Reactuation of the Containment

! Spray System in LOCA and E5D ORGs

, .. In the July 29, 1983 SER, the staff requested that guidance be included for reactuation of the containment spray system with respect to its influence on hydrogen flamability and flame propagation. It also requested that the envelope of containment conditions (hydrogen, steam, air concentrations) for which combustion would not jeopardize containment integrity be considered.

The guidelines for the LOCA and ESD ORGs have been modified to actuate containment spray anytime the containment pressure is greater than

[10psig]. If the containment pressure falls below [7 psig], then containment spray can be terminated, but will be reactuated if the containmentpressureagainexceeds[10psig]. Typically, containment spraysareautomatically]actuatedwhenthecontainmentpressureTherefore, increasesabove[10psig. since it

, the spr ys are terminated when the containment pressure falls below

[7 psig , they should be reactuated if the containment pressure increases above [10 psig], we conclude that the issue of reactuation of

the containment spray system in the LOCA and ESD ORGs is resolved.

The SFSC will transfer the operator from the LOCA or ESD ORGs to the FRGs when the hydro

.or greater than [4%;en ..

concentration within the containment is equal toFo hydrogen in air and will decrease in an air-steam mixture. Since the operator will remain in the LOCA or ESD ORGs only if the hydrogen concentration is below the lower flamability limit, the influence of the containment spray on hydrogen flammability was not addressed in the

! LOCA or ESD ORGs. The staff will reconsider the influence of containment spray on hydrogen flamability and the effect of hydrogen combustion on containment integrity in a future SER supplement when the guidelines are expanded to include severe accident mitigation. This area was identified as needing further consideration in the staff's July 29, 1983 SER.

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2.3 Item 3.4:2.3.c and Item 3.6.2.7.c - Selection of Hydrogen Control Actions in LOCA and ESD ORGs In the July 29, 1983 SER, the staff requested that the selection of hydrogen concentration for control actions that are close to hydrogen limits be justified with respect to instrumentation accuracy, uniformity of mixing, and accuracy with which the limits are known.

Submittal 1 of Revision 03 to CEN-152 has simplified the guidelines so that control actions that are based on hydrogen concentration occur in only a few places in the LOCA and ESD ORGs. The following actions are to be performed if the hydrogen concentration is:

. A. Greater than [0.5%], then energize the hydrogen recombiners; B. Less than [0.5%], then terminate operation of the hydrogen recombiners; and C. Less than [3.5%], then teminat'e operation of the hydrogen purge system. This action is only applicable to the LOCA ORG and not the ESD ORG since operation of the hydrogen purge system is not required for an ESD event.

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The 0.5% is a plant-specific value representing the minimum detectable hydrogen concentration inside the containment. The 3.5% value was chosen because it is 0.5% below the lower flammability limit of 4.0%,

and the instrument error associated with hydrogen measurement is typically 0.5%. Additionally, the Supplementary Information Section i indicates that measured hydrogen will typically indicate higher than

, actual containment hydrogen for a steam / air mixture inside containment.

Therefore, when hydrogen concentration limits are used for control actions, conservative values have been selected.

The bases for not providing guidance on the use of the hydrogen purge 6 system in the ESD ORG are given previously in paragraph 2.1.

With regard to the issue of uniformity of hydrogen mixing, the CEOG evaluation indicates that uniformity of mixing of hydrogen would not be a problem. Their studies indicate that in an environment with turbulence, the propensity of hydrogen to diffuse will overcome any l tendency to accumulate and will result in a relatively uniform mixture.

However, the guidelines do require the operation of the contai' ment emergency fan coolers [at 4 psig]. The circulation of the containment atmosphere by the fan coolers will help to assure a uniform concentration of hydrogen throughout the containment. In addition, the actuation of the containment spray [at 10 psig] will help promote mixing the hydrogen in the containment atmosphere so that there will be a L uniform hydrogen concentration within containment.

The staff has reviewed these changes to the LOCA and ESD ORGs and concludes that these changes resolve the concerns identified in Reference 1 with regard to selection of hydrogen control actions.

2.4 Item 3.4.2.3.d and Item 3.6.2.7.d - Instructions for Operation of Hydrogen Recombiners in LOCA and ESD ORGs .

- The staff's July 29, 1983 SER requested that instructions for operation of hydrogen recombiners be included or referenced in the guideli.nes.

Guidance on operation of the hydrogen recombiners has been added to the

'LOCA and ESD guidelines in Submittal 1 of Revision 03 to CEN-152. The guidance is intended to ensure that (1) the recombiners are made

. available before their use is required, (2) the recombiners are energized if conditions for generating hydrogen exist, and (3) the recombiners are energized anytime hydrogen can be detected.

Early in the accident, if a plant combustible gas control system utilizes an external hydrogen recombiner, instructions are provided to take steps to have the hydrogen recombiners made available and aligned for use. Anytime containment spray is actuated or the containment hydrogen concentration is greater than [0.5%], then the hydrogen recombiners are to be energized. The recombiners are to be energized when the spray is actuated because of the potential for generating

> hydrogen by the chemical reaction of the spray solution with aluminum and zinc materials inside containment.

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-+L- A- A. A -- - 6 ..tm' m The staff has reviewed the CEOG submittal regarding operation of the hydrogen recombiners for the LOCA and ESD ORGs. Based on the above discussion, the submittal provides adequate instructions for operation of hydrogen recombiners. . We, therefore, conclude that these changes are acceptable and resolve the concerns identified in Reference 1 regarding

operation of the hydrogen recombiners.

2.5 Item 3.4.2.3.f and Item 3.6.2.7.f - Containment and RCP Cooling Capability in LOCA and ESD ORGs s

In the July 29, 1983 SER, the staff requested that guidelines for operator actions to preserve containment cooling and RCP cooling i capability be considered in light of the potential for inadvertent isolation, or to reinstate cooling following automatic or operator initiated isolation.

Submittal 1 of Revision 03 has added guidance to the LOCA and ESD ORGs '

4 in CEN-152 regarding containment cooling. Containment emer coolers are started when the containment pressure exceeds 4 psig]. [gency All fan available normal containment equipment cooling systems and air recirculation systems are verified operating in both the LOCA and ESD

-ORGs. This verification in the LOCA ORG is performed when the containment pressure is greater than [4 psig]. In the ESD ORG, this verification is performed when the containment sprays are actuated.

In both ORGs, if the containment pressure is greater than [10 psig],

then adequate containment cooling is provided by one of the following configurations:

[a) at least three containment fan coolers operating in the emergency

mode j OR b) at least two containment fan coolers operating in the emergency mode and at least one containment spray header delivering at least 1500 gpm OR c c) two containment spray headers each delivering at least 1500 gpm].

Although the new guideline did not address RCP cooling capability in either the LOCA or ESD ORGs, the CEOG has comitted to address this issue in a future submittal.

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t The ' staff has reviewed these changes associated with containment cooling capability.. Based upon the above discussions which are consistent with FSAR assumptions, these changes provide acceptable guidelines to preserve containment cooling and reinstate cooling following automatic or operator initiated isolations. Since the changes are acceptable and address the staff's concerns with regard to containment cooling, this open item is partially resolved. The staff will address RCP cooling capability in a future supplement after the CEOG has addressed this issue in a future submittal.

2.6. Item 3.5.2.12.a and Item 3.7.2.5.a - Containment Hydrogen Control in the SGTR and LOF ORGs; Item 3.5.2.12.b and Item 3.7.2.5.b - Reactuation of Containment Spray System in the SGTR and ! OF ORGs; Item 3.5.2.12.c and Item 3.7.2.5.c - Selection of Hydrogen Control Actions in the SGIR and LOF ORGs; and Item 3.5.2.12.d and Item 3.7.2.5.d - Instructions for Operation of Hydrogen Recombiners-in the SGTR and LOF ORGs In its July 29, 1983 generic SER, the staff requested that the following instructions be provided in the SGTR and LOF ORGs:

A. . Guidance to reduce containment hydrogen concentration and/or preserve containment integrity by venting.

The generic SER indicated that since venting may release large

- quantities of radioactive material, it should be based upon a realistic appraisal of containment capability and purge / vent system operability under accident conditions. It was recommended that the

'l. guidance specify limits for operator actions.

B. Guidance for reactuation of the containment spray system with respect to its influence on hydrogen flammability and flame propagation.

The envelope of containment' conditions (hydrogen, steam, air concentrations) for which combustion would not jeopardize containment integrity was to be considered.

C. Guidance for the operator to take actions for various hydrogen concentrations.

The hydrogen concentrations that are close to burn and explosion limits should be justified with respect to instrumentation accuracy, uniformity of mixing, and accuracy with which the limits are known.

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l D. Guidance for operation of hydrogen recombiners. .

The CE0G has stated'that the SGTR and LOF events are not expected to '

produce measurable quantities of hydrogen in containment. The CE0G points out that a LOF is not a breach of the primary reactor coolant 4 '

system and that although a-SGTR is a breach of the primary reactor coolant system, there is no direct leakage from the reactor coolant system to the containment. Hence, a SGTR or a LOF event is not expected to produce hydrogen within the containment. That is, the containment 4 pressure and temperature are not expected to increase to actuate the containment sprays which have the potential to cause the production of

hydrogen. However, if the containment temperature and pressure increase above expected normal values, then the SFSC for the Containment Combustible Gas Control Safety Function will require the operator to exit the SGTR or LOF ORG and transfer to the appropriate FRG. The staff agrees with the CEOG that the SGTR and LOF are not expected to produce measurable quantities of hydrogen in the containment, and hence the SGTR and LOF ORGs need not contain guidelines on hydrogen control. The SFSC provides adequate guidance to the operator to transfer to the

• - appropriate FRG if conditions for hydrogen production exist inside containment. Therefore, the staff concludes that these open items are resolved. ,

2.7 Item 3.9.1.2.4 - Consistency of Containment Pressure Parameter in FRGs In its July 29, 1983 SER, the staff noted that Figure 10-2d of CEN-152, Revision 01 made references to containment pressure of [4] psig that were not consistent with other portions of the EPGs, such as the LOCA '

ORG, where [0.5] psig is used. Figure 10-2d provides the basis for the Containment Isolation SFSC.

. Submittal 1 of Revision 03 for CEN-152 has made substantial changes in the guidelines in the area of containment pressure control. This r revision removed any inconsistency in the use of the containment

, pressure which existed in previous revisions. Forexample,[4]psigis used through the EPGs as the Containment Isolation Actuation Signal setpoint. Because the EPGs now use consistent pressure setpoints for actions, the staff concludes that this open item has been resolved.

2.8 Item 3.9.6.2 - Containment Environment Control in FRGs In its July 29, 1983 SER, the staff requested that the containment guidance provided in the FRGs be extended to include guidance on containment environment control similar to that requested for the ORGs.

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Temperature and Pressure Control FRG and added a new FRG entitled ,

Containment Combustible Gas Control. The technical changes for these new FRGs are summarized below:

1. Containment Temperature and Pressure Control The new Containment Temperature and Pressure Control FRG contains three success paths instead of the two that were in Revision 01 to CEN-152. .The success path using the containment spray remains unchanged. The success path in Revision 01 using the containment fan cooling system has been divided into two success paths. The new FRG has a success path for containment fan coolers operating in the i, .

normal mode and a success path for fan coolers operating in the emergency mode. The previous guidance did not make any distinction between the two operating modes of the containment-fan coolers.

Since the separate success paths for the fan coolers operating in the normal mode and in the emergency mode will add clarity to the guidelines, this is acceptable to the staff.

Submittal 1 of Revision 03 for CEN-152 has changed the Containment NORMAL MODE The operator actions associated with the Containment Fan (Normal Mode) Success Path are:

a. Verify that [three] containment fan cooler units are operating in the normal mode, l b. Verify that containment temperature is less than [180*F;, and

c. Verify that containment pressure is less than [1.5 psig..

g The acceptance criterion for the normal mode success path is i satisfied if the containment pressure is less than [1.5 psig].

! Because 1.5 psig is typically the maximum containment pressure

observed during normal power operation, the staff finds it L - acceptable as the normal mode acceptance criterion.

EMERGENCY MODE

The operator actions associated with the Containment Fan (Emergency Mode) Success Path are

a. [ Verify automatic operation of the containment fan cooling i

system in the emergency mode at the plant-specific setpoint. If at'least three containment fans are not running in slow, then they should be started manually.] and

b. Ensure cooling water is aligned to the containment fan cooling system. .

The acceptance criteria for the emergency mode success path are satisfied if:

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a. [At least three] containment fan coolers are, operating in the emergency mode, and

b. Containment temperature and pressure are constant or decreasing.

Since these criteria are consistent with credit assumed for containment cooling FSAR calculations, the staff finds them acceptable as the emergency mode acceptance criteria.

2. Containment Combustible Gas Control n .The Containment Combustible Gas Control FRG consists of two success paths. One success path is associated with the use of hydrogen recombiners and the other path is associated with the use of the hydrogen purge system.

l HYDROGEN RECOMBINERS J

The. operator actions associated with the Hydrogen Recombiner Success Path are:

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a. Place the hydrogen monitor in service. .

b. [If the containment combustible gas control system utilizes external hydrogen recombiners, then take steps to have the recombiners made available and aligned for use.]

c. Ensure all available containment air recirculation systems are operating. These include containment dome air recirculation systems, Control Element Drive Mechanism (CEDM) cooling system, reactor vessel cavity cooling system, and [any other plant-specificsystem.]

If the containment hydrogen concentration is greater than

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y [0.5%], then take steps to energize the hydrogen recombiners.

e. If the containment sprays have been actuated, then take steps to

! energize the hydrogen recombiners.

f. If the containment concentration is less than [0.5%],-then the hydrogen recombiners should be de-energized.

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-The acceptance criteria for the Hydrogen Recombiner Success Path are satisfied if:

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a. Hydrogen concentration is less than [0.5%],

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b. 1) At least one hydrogen recombiner is energized.

AND ii) Hydrogen concentration is less than [4%].

HYDROGEN PURGE SYSTEM The operator actions associated with the Hydrogen Purge System Success Path are:

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a. Place the hydrogen monitor in service,

b. Ensure all available containment air recirculation systems are operating. These include containment dome air recirculation system, CEDM cooling system, reactor cavity cooling system, and

[any other plant-specific systems].

c. If the [ Plant Technical Support Center] has reviewed and recommended hydrogen purge, then start the hydrogen purge system.

The acceptance criteria for the Hydrogen Purge System Success Path is satisfied if the hydrogen concentration is less than [4%].

. The purpose of the Containment Combustible Gas Control FRG is to prevent the hydrogen concentration in the containment atmosphere from increasing to the flammable concentration. A hydrogen burn inside containment could cause damage to the containment building or equipment. To achieve control of the containment hydrogen concentration, the FRGs use two methods: (1) hydrogen recombiners and (2) hydrogen purge systems. Actions are taken to maximize the mixing and recirculation of the containment atmosphere to reduce the possibility of local accumulations of hydrogen reaching the flamable concentration. Recombiners are energized as soon as any hydrogen can be detected and operated until no detectable hydrogen is present in the containment atmosphere. The lower flamability limit for hydrogen is 4%. The combustible gas control FRG is intended to maintain the hydrogen concentration below this limit by operation of the hydrogen recombiner or hydrogen purge system.

The staff has reviewed the success paths for the Hydrogen Recombiners and for the Hydrogen Purge System associated with the Combustible Gas Control System FRG. Because the Hydrogen Recombiner l'[ Success Path provides timely actions for mixing of the containment atmosphere, placing the recombiners in service, and taking them out

, of service when no longer needed, the staff concludes that tb-Hydrogen Recombiner Success Path and acceptance criteria :,it j acceptable for the control of hydrogen. However, the Hydrogen Purge

, System Success Path does not contain guidance on the use of the l iodine removal system, criteria for purging of the containment, or guidance on when the hydrogen purge can be teminated. Prior to the

l. use of the hydrogen purge system, the iodine removal system should be operated to reduce the airborne radiation level in the i containment atmosphere. The guidelines should identify the factors t that should be considered when purging. (See operator action item C.) Although the SFSC acceptance criterion is satisfied if the

14 guidance on when the hydrogen purge can be terminated. Prior to the use of the hydrogen purge system, the iodine removal system should

.be' operated to reduce the airborne radiation level in the containment atmosphere. -The guidelines should identify the factors that should be considered when. purging. (See operator action item C.) Although the SFSC acceptance criterion is satisfied if the

-hydrogen concentration is less than [4%], no. instruction is provided on when purging can be terminated. By teminating the purge when o the hydrogen corcentration is below the flammable limit (4%),

unnecessary offsite doses could be avoided. See the additional discussion on more specific criteria for purging the containment in paragraph 2.1. Therefore, we conclude that hydrogen purge system FRG should be expanded to. include: (1) the use of the iodine

-removal system, (2) criteria for purging the containment, and (3) guidance on when purging can be terminated.

Because the current FRG revision is an improvement over the previous

- Revision 02 of the EPGs in the area of hydrogen control, and because of the low probability of occurrence of an event which would require the use of this guidance, the three residual issues listed above can be addressed in the long tem. Therefore, interim implementation is acceptable. We will address resolution of these items in a future SER supplement.

2.9 Item 3.9.7.2.1 - Long-Tem Operator Actions in ORGs and FRGs

-In the July 29, 1983 SER, the staff recomended that the objective of

' long-term operator actions should be to place the plant in a condition where other procedures apply, with a suitable interface with those 'other procedures; or to place the plant in a controlled, stable condition that

,~ is expected to last sufficiently long for support personnel to provide guidance for future actions. Also, because entry into the long-term i actions required stable plant conditions, the SER recomended that j either guidelines be provided that result in a stable plant, or the

, long-term actions be made consistent with the unstable but controlled l . conditions that may result from the prior guidance.

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Submittal 1 of Revision 03 has changed the Long-Term Operator Actions.

There is no longer the condition that a stable plant exi'st for application of the long-term actions. Since the FRGs may be implemented for a variety of different events, the long-term actions strategies are made flexible. The basic strategy is to: continuously maintain the SFSC acceptance criteria, determine if a cooldown is urgent, maintain the abilit necessary)y , andtocontinuously cooldown, attempt cooldown and implement to diagnose the eventshutdown if not cooling (if already diagnosed. Since the detailed course of the long-term actions to be taken will depend on the nature of the event, the operator will rely on the Plant Technical Support Center staff for further guidance.

In many cases, the exit from the emergency procedures will be to shutdown cooling system operation. The guidelines recomend that the b shutdown cooling system operating procedure contain an instruction to return to the emergency procedure previously in use or to the functional recovery procedure if complications arise during the shutdown cooling operation.

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In addition to the changes made to the FRGs, each ORG was expanded to include its goals and exit conditions. The goals will provide better

, ;- guidance to the operator regarding when the ORG has accomplished its purpose, and exit conditions will inform the operator what conditions have to be met to exit the ORG. Once in the long-term actions, the plant is either brought to a controlled, stable shutdown condition, or the safety functions are maintained until guidance is provided by the plant technical support center. In addition, the guidelines recomend that the shutdown cooling system operating procedure contain instructions to return to the guidelines if problems arise during

~j. cooldown. Because the guidelines now provide guidance for exiting to j other procedures and because stable plant conditions are no longer j required for entry into the long-tenn actions, the staff concludes that this open item is resolved.

3.0 CONCLUSION

Based on our review of the July 1, 1985 Submittal 1 of Revision 03 to CEN-152, " Combustion Engineering Emergency Procedure Guidelines " the staff concludes that the following items identified in our July 29, 1983 SER have been resolved as described in Section 2 of this SER.

A. 3.4.2.3.b - Reactuation of the Containment Spray System in LOCA ORG B. 3.4.2.3.c - Selection of Hydrogen Control Actions in LOCA ORG C. 3.4.2.3.d - Instructions for.0peration of Hydrogen Recombiners in LOCA ORG 4

D. 3.5.2.12.a - Containment Hydrogen Control in the SGTR ORG i

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E. 3.5.2.12.b - Reactuation of the Containment Spray System in SGTR

~

ORG F. 3.5.2.12.c - Selection of Hydrogen Control Actions in SGTR ORG G. 3.5.2.12.d - Instructions for Operation of Hydrogen Recombiners in ,

SGTR ORG H. 3.6.2.7.b - Reactuation of Containment Spray System in ESD GRG I. 3.6.2.7.c - Selection of Hydrogen Control Actions in ESD ORG 4

J. 3.6.2.7.d - Instructions for Operation of Hydrogen Recombiners in ESD ORG K. 3.7.2.5.a - Containment Hydrogen Control in LOF ORG L. 3.7.2.5.b - Reactuation of Containment Spray System in LOF ORG M. 3.7.2.5.c - Selection of Hydrogen Control Actions in LOF ORG N. 3.7.2.5.d - Instructions for Operation of Hydrogen Recombiners in LOF ORG

0. 3.9.1.2.4 - Consistency of Containment Pressure Parameter in FRGs P. 3.9.7.2.1 - Long-Term Operator Actions in ORGs and FRGs The following items have been partially resolved as described in Sections 2.1, 2.5 and 2.9 of this SER:

A .- 3.4.2.3.a - Containment Hydrogen Control in LOCA ORG B. 3.4.2.3.f - Containment and RCP Cooling Capability in LOCA ORG C. 3.6.2.7.a - Containment Hydrogen Control in ESD ORG <

D. 3.6.2.7.f - Containment and RCP Cooling Capability in ESD ORG E. 3.9.6.2 --Containment Environment Control in FRGs We note that the CEOG resolution of hydrogen-related open issues to date have been generally confined in scope to design basis accidents,

and did not address the adequacy of combustible gas control strategy for dealing with severe accidents. For severe accidents, combustible gas .

production rate could exceed the capacity of the recombiners and '

necessitate such last-resort measures as containment venting for hydrogen control, containment venting for long-term pressure control, containment spray operation for post-burn equipment cooling, and primary

- system venting via the high point vents. Severe accident mitigation is an area for which the staff. recommended in Reference 1 that further guidance be provided in the EPGs. The inclusion of additional severe accident guidance in the EPGs may affect many areas, including containment environment control. Our conclusion that the foregoing open

! items have been resolved is subject to added considerations in the l severe accident area in the longer term.

Therefore, witn the previous modifications des:ribed in our Supplement 1 SER dated April 16, 1985 (these modifications address the use of reactor vessel level instrumentation and reactor vessel upper head voiding),

Submittal 1 to Revision 03 of CEN-152 is acceptable for implementation

and will provide improved guidance for emergency operating procedure

! development. Resolution of the remaining areas identified above, as well as the issues remaining in the July 29, 1983 SER, will be addressed l in future supplements.

L

4 4.0 ACKNOWLEDGEMENTS .

Principal Contributor: T. Green, Procedures.and Systems Review Branch, DHFS.

5.0 REFERENCES

1. Letter, D. G. Eisenhut (NRC) to R. W. Wells (CE0G), " Safety Evaluation of Emergency Procedure Guidelines," dated July 29, 1983.

2. Letter, R. W. Wells (CE0G) to D. G. Eisenhut-(NRC), " Combustion Engineering Owners Group Plan for Resolution of CEN-152,

. Revision 01, SER Open Items," dated October 19, 1984.

3. Letter, R. W. Wells (CE0G) to D. G. Eisenhut (NRC), " Transmittal of CEN-152, Revision 02, ' Combustion Engineering Emergency Procedure Guidelines'," dated May 8, 1984. ,

4. Letter, R. W.. Wells (CEOG) to D. G. Eisenhut (NRC), " Transmittal of

'- Appendix A to CEN-152, " Revision 02, ' Response to NRC Core Performance Branch Questions on CEN-152, Revision 02'," dated-November 26, 1984.

5. " Clarification of TMI Action Plan Requirements," NUREG-0737, November 1980.

6. " Clarification of TMI Action Plan Requirements," NUREG-0737, Supplement 1, January 1983.

{ 7. " Justification of Trip Two/ Leave Two Reactor Coolant Pump Trip Strategy During Transients," CEN-268, dated 1984.

1 8. Letter, J. Zwolinski (NRC) to R. W. Wells (CEOG), " Combustion .

Engineering Owners Group Plan for Resolution of CEN-152, Revision 01, SER Open Items," dated February 25, 1985.

9. Letter,J.Zwolinski-(NRC) tor.W. Wells (CEOG),"Supplemet.t1to Safety Evaluation for CEN-152, ' Combustion Engineering Emergency Procedure Guidelines'," dated April 16, 1985.

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