ML20141K925

Responds to Re Subject of Reactor Safety Margin. Listed Issues Raised in Ltr.Nrc Will Address Subj Issues in Order Raised in Ltr

ML20141K925
Person / Time
Site:	Maine Yankee
Issue date:	05/23/1997
From:	Collins S NRC (Affiliation Not Assigned)
To:	Lochbaum D UNION OF CONCERNED SCIENTISTS
References
NUDOCS 9706020130
Download: ML20141K925 (6)

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't UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 3086b0001 y* *4 *** /

May 23, 1997 l

Mr. David A. Lochbaum Nuclear Safety Engineer l Union of Concerned Scientists 1616 P Street., NW, Suite 310 l Washington, DC 20036 l

Dear Mr. Lochbaum:

l 1 am responding to your letter to me of March 21, 1997, on the subject of t

reactor safety margin. In your letter, you clarified the positions previously stated in your letter of January 6,1997, to Hubert J. Miller, Regional Administrator, Region I, U.S. Nuclear Regulatory Commission (NRC), regarding licensee nonconformance with NRC regulations. You also commented on NRC's policy on allowing plants to continue to operate when a licensee has determined that it is not in conformance with its design or licensing bases.

I will address these issues in the order you raised them in your letter.

t In clarifying your positions on a licensee's nonconformance with its design and licensing bases, you first stated that "when a licensee makes a physical change to the facility to correct a nonconformance, it is reasonable to conclude that these actions restored safety margin that had otherwise been missing." This is a reasonable conclusion.

You later take this conclusion a ster further to indicate that you believe that "the NRC's cwn expectations would dictate that nonconformance resolved by physical plant changes must be considered to reflect prior unsafe operations unless specific evaluations indicate adequate margins existed."

I do not agree with your assertion that a licensee's decision that a system, structure, or components may not be able to perform its safety function (i.e., is operable) equates to unsafe operation. For example, Generic Letter (GL) 91-18, "Information to Licensees Regarding Two NRC Inspection Manual Sections on Resolution of Degraded and Nonconforming Conditions and on Operability," directs licensees, if a nonconforming condition which also may pose an immediate threat to public health and safety is identified, to first place the plant in a safe condition, then proceed with restoring the system, t/ '/-/bl-structure, or component to the current licensing basis. See Technical Guidance, " Resolution of Degraded and Nonconforming Conditions," Section 4.1.

A plant's li:ensing and design bases include substantial margin. Acceptance limits in a plant's final safety analysix .,, ort or the staff's safety evaluation report are conservatively chov.... Therefore, not meeting a regulatory limit does not necessarily equate to an unsafe condition. The i

guidance in GL 91-18 notes that licensees should be conservative in making an l

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i operability determination. Specifically, " Operable / Operability," Section 3.3

of the technical guidance states that "[w] hen system capability is degraded to a point where it cannot perform with reasonable assurance or reliability, the system should be judged inoperable, even if at this instantaneous point in time the system could provide the specified safety functions."

As I stated in my letter of February 27, 1997 to you, although compliance with the Commission's regulations, as a genera,l matter, provides reasonable assurance of protection of public health and safety, the agency must exercise its judgement regarding thresholds for determining the safety of plant operation. Also, the NRC's approach to protecting public health and safety is

- based on the' philosophy of defense in depth. The appropriate regulatory response to an identified deficiency can and should vary, depending on the safety significance of the identified deficiency.

Additiont11y, when a licensee discovers a nonconforming condition, it examines its options and may select the most expeditious means for correcting the nonconformance and restoring or revising regulatory margin, it may be more expedient for a licensee te make a modification to the plant than to perform the analysis necessary to demonstrate that the current condition of the plant would still provide adequate safety margin.

Finally, with regard to the findings of the Maine Yankee Independent Safety Assessment Team (ISAT), you stated that you "do not understand how it can possibly be more prudent, from a nucler.r safety perspective, to require a licensee to correct nonconformances when a plant is shut down than when the plant is operating....[or how] a problem....could be so significant as to prevent a plant from starting up yet be so insignificant as to not warrant shutting that plant down if it were operating....In short, the NRC cannot wait until some other event causes the plant to shut down before running in wich a long list of safety issues that must be resolved."

First, unless a nonconformance poses an undue risk to public health and safety, it is not prudent to require a plant to shut down and thus risk that a plant transient might occur and increase operational risks. Once a plant is shut down, however, it may be more prudent to correct the nonconformance before allowing startup, because a delayed startup does not usually leave a plant in a condition that could cause an undesirable transient.

Moreover, in the case of Maine Yankee, the staff continued to conduct inspections and to evaluate certain nonconformances after issuance of the ISAT Report on October 7, 1996. The NRC staff issued Confirmatory Action Letter 1-96-015 (December 18,1996) and Confirmatory Action Letter 1-96-015, Supplement 1 (January 30,1997) to address problems fully evaluated or first identified after issuance of the ISAT Report, and to document the licensee's

D. Loc 5brum -3_ May 23,1997 agreement to take s:ertain corrective action before restart. Additionally, actions necessary to correct some of the nonconformances at Maine Yankee can be performed only during a plant shutdown.

I trust this discussion provides you with a clearer understanding of the NRC's policy on which our guidance to licensees regarding nonconforming conditions is based. Note that the NRC recently published NUREG-1606, " Proposed Regulatory Guidance Related to Implementation of 10 CFR 50.59 (Changes, Tests, or Experiments)" for public comment and that we are continuing to evaluate our positions on many of the issues discussed in the NUREG, including those raised in your letter.

I Sincerely, n i det LY.

Samuel J.M ollin irector Office oMuclear P.eactor Regulation l

e D. Lochbaum -3_ May 23, 1997 i agreement to take certain corrective action before restart. Additionally, actions necessary to correct some of the nonconformances at Maine Yankee can be performed only during a plant shutdown.

I trust this discussion provides you with a clearer understanding of the NRC's policy on which our guidance to licensees regarding nonconforming conditions is based. Note that the NRC recently published NUREG-1606, " Proposed Regulatory Guidance Related to Implementation of 10 CFR 50.59 (Changes, Tests, or Experiments)" for public comment and that we are continuing to evaluate our positions on many of the issues discussed in the NUREG, including those raised in your letter.

Sincerely, Original signed by Frank J. Miraglia Samuel J. Collins, Director

" Office of Nuclear Reactor Regulation

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9 DISTRIBUTION: See attached page DOCUMENT NAME: G:\siml\YT970039 See Previous Concurrences

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m l UNION OF l<- CONCERNED SCIENTISTS March 21,1997 Mr. Samuel J. Collins, Director Office of Nuclear Reactor Regulation United States Nuclear Regulatory Commission l Washington, DC 20555-0001 SUBJECf: REACTOR SAFETY MARGIN

Dear Mr. Collins:

Thank you for your letter dated February 27,1997, in response to my letter of January 6,1997, to Mr.

Hubert J. Miller, Regional Administrator, Region 1.

In your response, you indicated that I had implied that any licensee's failure to comply with the NRC's regulations corresponds to that licensee's facility having been operated unsafely during the period of nonconformance. That has never been my position, so I will attempt to clarify what I am advocating.

l The safety implications of any nonconformance,in my opinion, are best measured by the corrective actions implemented by the licensee to resolve it. The originally reviewed and approved safety margins a: the facility are clearly unaffected when the licensee is able to address a nonconformance via " soft" actions, such as successfully completing a surveillance test that had not been performed on time or accepting an apparent degraded condition as-is based on a. rigorous engineering evaluation.

However, when the licensee makes a physical change to the facility to correct a nonconformance, it is reasonable to conclude that these actions ustond safety margin that had otherwise been missing.

By way of illustration, consider a facility with a technical specification limit that containment ambient

air temperature must'be <120'F. The accident analyses of design bases events assume an initial l ambient air temperatute of 120'F in the containment. The licensee verifies compliance with the

technical specification by averaging a number of temperature instruments located within the containment. The licensee reports a nonconforming condition when it discovers that the methodology used to calculate average ambient air temperature is nonconservative by up to 8'F. A review of past operating data reveals that temperatures of Il6-119'F had routinely been experienced during full power operation in past summer months.

If the licensee reanalyzed all applicable design bases events for an initial ambient air temperature of

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130*F in the containment and determined margin to safety limits, then it would be appropriate to  :

conclude that the facility had not been operating unsafely. The physical plant configuration of the l facility was adequate despite the nonconformance.

Washington Office: 1616 P Street NW Suite 310

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e However,if the licensee upgraded the containment cooling system to maintain the cometed ambient air temperature of the containment $120*F, then it would not appropriate to conclude that the facility had been operating unsarcly. The physical plant configuration of the facility was inadequate. This -

' situation also applies in the case where the licensce revises procedures to direct its operating stafr to start another containment cooling unit when necessary to maintain the uncometed ambient air temperature below 110*F (i.e., to maintain the corrected ambient air temperature below 120*F).  !

My position on the safety implications of nonconformances appears consistent with the guidance provided by the NRC to its licensees in Generic Letter 91-18, "Information to Licensee Regarding Two NRC Inspection Manual Sections on Resolution of Degraded and Nonconforming Conditions and on Operability." This guidance permits remondle eng!neeringfudgement to be used to determine that a safety function can be perfonned by a system, structure on component despite the nonconfonning l condition. When a licensee makes a physical change to the plant to resolve a nonconformance, remondle enginceringfudgement should conservatively conclude that the safety function could not be peifonned un!ca there is an analysis showing that margin existed in the nonconforming condition.

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This position is further reinforced by NRC actions relative to nonconservative decision making by licensces. Following the marsh grass event at Salem in April 1994, the NRC was very critical of the decision-making by the licensee's operating staff. The NRC was also critical of the command and control capabilities of the operating staff at Zion during this month's inadvertent shutdown and restart l cvent. The NRC has repeatedly informed its licertsees that it expects them to make conservative decisions when faced with uncertain and unanalyzed situations. Thus,it seems that the NRC's own expectations would dictate that nonconformances resolved by physical plant changes must be considered to rcilect prior unsafe operations unless specific evaluations indicate adequate margins existed Absent such evaluations, the conservative decision must be to assume that adequate margin did nel exist for the nonconforming conditions.  !

l It is from this perspective that I evaluate the safety implications of nonconformances. It is why 1 l cannot reconcile the findings of Maine Yankcc's Independent Safety Assessment Team (ISAT) with j the reassuring statements made to the public by NRC officials. The ISAT documented numerous nonconformances involving safety systems that were resolved by physical plant changes. The ISAT conducted vertical slico evaluations of four of the top five risk significant systems as ranked by the Maine Yankee licensce in its Individual Plant Examination The ISAT documented missing wiring for the High Pressure Safety injection (HPSI) pump, inadequate ventilation for the containment spray pump rooms, lack of overpressure protection for piping penetrating the contamment, and numerous other prob! cms. While some of these problrms were resched by "soA" setions, many of them involved physical plant changes. I am not aware of any evaluation perfonned by the licensee or by the NRC that would indicate that this facility had adequate safety margin with all of these nonconforming conditions existing prior to their resolution. In fact, the licensee reported that the missing HPSI pump wiring done increased the core damage frequency at Mainc Yankee by 6%.

Therefore, any NRC oUicial who concludes that Maine Yankee was not being operated unsafely with all of these nonconforming conditions is making, in my opinion, a nonconservative decision that is contrary to the expectations established by the NRC for its licensees..

My concern over the safety implications of nonconformances goes beyond the issue of the NRC's credibility in its dealings with the public. In your response to my lever, you stated: )

! NRC Generic Letter 91 18, "Information to Licensec Regarding Two NRC Inspection Manual l l Sections on Resolution of Degraded and Nonconforming Conditions and on Operability,"

! provides guidance for licensees when they identify degraded or nonconforming conditions.

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l However, once a plant has been shut down, for whatever reason, it is often more prudent to  !

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permit restart only after significant nonconformances have been corrected. Thus, it is possible i that a particular deficiency that would have been insufficient by itself to warrant shutdown of a plant might be sufficient to warrant repWr prior to restart. ,

i I confess that I do not understand how it can possibly be more prudent,from a nuclear safety j perspective, to require a license to correct nonconformances when a plant is shut down than when the l plant is operating. I also do not understand how a problem, or even a parcel of problems, could be so l significant as to prevent a plant from starting up yet be so insignificant as to not warrant shutting that l plant down were it operating. The criteria for determining if a plant is safe to operate must be l independent of the plant's operating condition. The reasonable assurance threshold that a system, l structure, or component can pe form its safety function cannot be lower when a plant is running than when it is shut down - that is inversely proportional to the risk and quite frankly potentially dangerous. In short, the NRC cannot wait until some other event causes the plant to shut down before running in with a long list of safety issues that must be resolved. Such behavior has at least two adverse consequences: it erodes public confidence in the NRC's regulatory oversight function and it provides incentive for licensees to keep problem plants running under degraded conditions.

I realize that the NRC is reviewing its inspection and enforcement programs based on lessons learned

!, from Millstone, Salem and Maine Yankee. I am prepared to assist the enhancement of these vital l programs in any way that I can. Please do not hesitate to contact me if further clarification of my.

j position is required or ifI can answer any questions related to my concerns.

Sincerely, l

l002 d 0'

• i David A. Lochbaum l Nuclear Safety Engineer i

l cc: Chairman Shirley Ann Jackson Commissioner Edward McGaffigan, Jr.

l United States Nuclear Regulatory Commission United States Nuclear Regulatory Commission l

[ Washington, DC 20555 Washington, DC 20555 l

l Commissioner Kenneth C. Rogers Mr. Philip A. Olson, Rm. 2440 l United States Nuclear Regulatory Commission United States General Accounting Office Washington, DC 20555 ,

Washington, DC 20548 l Commissioner Greta J. Dieus l United States Nuclear Regulatory Commission Washington, DC 20555 i Commissioner Nils J. Diaz i United States Nuclear Regulatory Commission Washington, DC 20555 l

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! Mr. Sarnuel J. Collins 3

Director of the Office of Nuclear Reactor Regulation 3

United States Nuclear Regulatory Commission ,

Washington, DC 20555-0001

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