ML20195C394

Discusses Results of Backfit Review Panel Re Emergency Preparedness Requirements for Maine Yankee Panel Determined That Staff Not Imposed Backfit on Licensee.Other Issues, Which Arose During Panel Deliberations,Identified & Encl

ML20195C394
Person / Time
Site:	Maine Yankee
Issue date:	10/28/1998
From:	Congel F, Lainas G, Zwolinski J NRC (Affiliation Not Assigned), NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:	Collins S NRC (Affiliation Not Assigned)
Shared Package
ML20195C381	List: ML20195C377 ML20195C394
References
NUDOCS 9811170100
Download: ML20195C394 (14)

Text

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\;*****# ' October 28, 1998 MEMORANDUM TO: Samuel J. Collins, Director Office of Nuclear Reactor Regulation FROM: Backfit Review Panet:

John A. Zwolinski, Acting Director -

Division of Reactor Projects I/II Office of Nuclear Reactor Regulation Gus C. Lainas, Acting Director .

Division of Engineering V Office of Nuclear Reactor Regulation Frank J. Congel, Director incident Response Division Office of Analysis and Evaluation of Operational Data

SUBJECT:

RESULTS OF BACKFIT REVIEW PANEL REGARDING EMERGENCY PREPAREDNESS REQUIREMENTS FOR MAINE YANKEE

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l On June 9,1998, the Backfit Review Panel (Panel) was appointed to determine if the criteria being used by the staff in evaluating a Maine Yankee request for relief from offsite emergency preparedness requirements of 10 CFR 50.54(q) constitute a backfit. The results of the Panel's j efforts are attached. The Office of the General Counsel has reviewed the Panel's report and l has no legal objection to the Panel's findings.

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The Panel reviewed numerous documents with varying degrees of relevancy to this matter.

Also, on July 9,1998, the Panel met with key Office of Nuclear Reactor Regulation (NRR) staff

( involved in the processing of the emergency preparedness exemption request. On July 10,

l. 1998, the Panel met with the licensee to discuss its backfit appeal in a meeting open for public i

observation. The meeting was transcribed. The Panel has followed the guidance contained in NRR Office Letter No. 901, " Procedures for Managing Plant-Specific Backfits and 10 CFR 50.54(f) Information Requests." The licensee argues that the criterion being imposed for review of its emergency preparedness exemption request is a backfit as the accident being postulated is considered to be outside the Maine Yankee licensing basis and, in addition, is a beyond-design-basis event. The licensee has also brought into question other issues such as backfit protection when seeking to amend its license.

The Panel has determined that the staff has not imposed a backfit on the licensee. However, the Panel has concluded that the criterion being used by the staff appears to be overly conservative, seeking to achieve a safety finding that is much more conservative than a traditional risk-informed reasonableness threshold. The basis for this conclusion is contained in

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the attached report. Other issues, which arose during the Panel's deliberations, are identified. I I

These include the applicability of 10 CFR 50.109 to plants in a decommissioning mode and protection provided all licensees when exemption / amendment requests are made of the staff.

The attachment has been developed such that it is in a format to transmit to the licensee in response to its letter of May 6,1998.

The Panel is available to meet with you should questions exist.

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Attachment:

l Maine Yankee Backfit Review Panet Results I

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MAINE YANKEE BACKFIT APPEAL PANEL RESULTS TABLE OF CONTENTS

1. BACKGROUND

11. BACKFIT APPEAL 111.

THE LICENSEE'S ASSERTIONS AND THE PANEL'S CONCLUSIONS Assertion 1 Assertion 2 Assertion 3 Assertion 4 Assertion 5 IV.

SUMMARY

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4 BACKFIT REVIEW PANEL RESULTS ON THE APPROPRIATE USE OF A POSTULATED ZlRCONIUM FUEL CLADDING FIRE IN A SPENT FUEL POOL AS THE CRITERION TO FORM THE BASIS TO GRANT EMERGENCY PLANNING EXEMPTIONS

1. BACKGROUND On November 6,1997, Maine Yankee Atomic Power Company (the licensee) submitted an exemption request to allow Maine Yankee to discontinue certain aspects of offsite Emergency Planning (EP). At a meeting with the licensee on November 25,1997, the staff informed the licensee that a finding would have to be made that Maine Yankee was no longer vulnerable to an event that could exceed the Environmental Protection Agency's (EPA's) Protective Action Guides (PAGs) and that spent fuel pool heat up analysis would be part of the review.

On February 17,1998, the licensee transmitted a letter to the staff claiming the staff was using acceptance criteria and taking positions more stringent than those previously accepted in the Maine Yankee licensing basis, thus, claiming a backfit existed. The staff responded to the licensee in a letter dated April 21,1998, from Jack Roe, the Acting Director, Division of Reactor Program Management, to Mr. Meisner, President, Maine Yankee Atomic Power Company, denying the licensee's claim of backfit. The staff concluded that the "Backfit Rule was intended to assure that once the Nuclear Regulatory Commission (NRC) issued a license, the terms and conditions for operating under the licens.e and regulations at the time of initial licensing are not arbitrarily changed post hoc by the Commission." Further, that when a licensee seeks an exemption, the licensee "is requesting authority to do what is not currently permitted under its license" and the licensee "has no valid expectations protected by the backfit rule regarding the terms and conditions for obtaining the new authority which is not permitted under the regulations." Additionally, the letter stated that "to grant the exemption is discretionary...and would not be considered backfitting so long as: (l) there is a rational basis for the new requirements and (ii) there is reasonable nexus between the new requirements and the subject matter of the exemption *--that is, that staff h as a fully rational basis for seeking new information to make a finding that an appropriate basis exists to grant the exemption. The staff believed that the analysis it requested from Maine Yankee was necessary to provide assurance that the radiation doses would not exceed the alert emergency classification, thus, obviating the need for offsite emergency msponse capability.

On May 6,1998, Maine Yankee sent a letter to the Executive Director of Operations appealing the staff's findings contained in the April 21,1998, letter. Subsequently, that matter was referred to the Office of Nuclear Reactor Regulation (NRR).

On June 9,1998, senior NRC managers were appointed to a Backfit Review Panel (Panel) to evaluate the criteria being used by the staff to render a finding in support of a Maine Yankee-proposed exemption regarding EP. On July 9,1998, the Panel met with key NRR staff involved in the processing of the exemption request. On July 10,1998, the Panel met with Maine Yankee to discuss its backfit appealin a meeting open for public observation. Three members of the public provided additional comments. The meeting was transcribed. The Panel has followed the guidance contained in NRR Office Letter No. 901, " Procedures for Managing Plant-Specific Backfits and 10 CFR 50.54(f) Information Requests." The primary issue of concem is the

• 1 criterion being applied by the staff in order to make a safety finding and, thus, develop a basis to '

grant an exemption to 10 CFR 50.47. The licensee argues that the criterion being imposed is a  !

backfit as the accident being postulated is considered outside the Maine Yankee licensing basis and, in addition, is a beyond-design-basis event. The licensee has also brought into question another issue regarding backfit protection when seeking to amend its license and other concems.

II. BACKFIT APPEAL in its May 6,1998, letter and in the subsequent interactions with the staff, the licensee appealed the staff's decision based largely on the following assertions:

1. The backfit rule shoukt apply to decommissioning plants.

2. The backfit rule should n 't distinguish between licensee-initiated requests and NRC-initiated actions.

3. It is a violation of the backfit rule to review an exemption request against accident sequences and associated assumptions beyond those considered in the existing licensing basis.

4. A NUREG cannot be used as the basis to impose new or additional requirements on li:ensees.

5. The licensee further characterized another regulatory burden imposed by the staff to be a ,

backfit; viz., the licensee was required not only to perform an acceptable analysis, but also to provide the NRC with information, support, and assistance, as necessary, to allow the NRC l to perform its own analysis verifying the licensee's fulfillment of the new criterion. '

l The Panel reviewed the licensee's request, the arguments presented in the materials provided, information obtained in the meetings conducted with the staff, and the history of the staff's disposition of similar requests.

Ill. THE LICENSEE'S ASSERTIONS AND THE PANEL'S CONCLUSIONS The licensee's backfit claim and subsequent appeal grew from its perception of the bases that the staff proposed to use to grant the exemption. Therefore, before discussing Maine Yankee's assertions, it is appropriate to discuss exemptions. Pursuant to 10 CFR 50.12(a), the Commission may, upon application by any interested person or upon its own initiative, grant exemptions from the requirements of the regulations that are (1) authorized by law, will not present an undue risk to public health and safety, and are consistent with the common defense and security, and (2) present special circumstances. The underfying purpose of Section 50.54(q) from which Maine Yankee sought exemption is to ensure that licensees follow and maintain in effect emergency plans that provide reasonable assurance that adequate protective measures can and will be taken in the event of an emergency at a nuclear reactor. The regulations are intended to provide protection from generally credible beyond-design-basis accidents. To grant an exemption from offsite EP requirements, the NRC must find that the proposed exemption does not compromise public health and safety in the event of these beyond-design-basis accidents.

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Assertion 1: The backfit rule as it applies to decommissioning plants.

The licensee argued that the explicit terms of the backfit rule apply to plants undergoing decommissioning because these plants are required to adhere to the provisions of 10 CFR Part 50. The licensee further stated that decommissioning plants need and are entitled to the l same predictability, stability, and protection from arbitrary actions as operating plants.

The Panel reviewed the history of similar requests and the staff's granting of EP exemptions to Rancho Seco, Yankee Rowe, and Trojan.

Rancho Seco The EP was revised to reflect the shutdown and defueled status of the reactor. The licensee's submittalincluded several attachments to justify the proposed changes to the EP and a request l

for an exemption to cease offsite emergency response and preparedness activities.

The staff reviewed the EP based on the standards of 10 CFR 50.47(d), which state the requirements for a license authorizing only fuelloading and low-power testing. The standards of 10 CFR 50.47(d) recognize the lower risk associated with low-power operation and were considered by the staff to be generally appropriate for reviewing the offsite aspects of the defueled EP. The staff determined that the radioactive source terms for an accidental release were greatly reduced by radioactive decay with time.

! Based on a review of the Sacramento Municipal Utility District's analysis of possible events at Rancho Seco, the staff concurred with the licensee's analysis and concluded that there is no credible accident for Rancho Seco in the defueled condition that could result in the release of radioactive materials to the environment in quantities that would require prompt protective actions for the public.

Yankee Rowe The staff used the same acceptance criteria for the review as was used to evaluate the adequacy of onsite emergency plans for operating nuclear power reactors, taking into

consideration the current shutdown status and inherent low risk of Yankee Rowe. The radioactive source terms for an accidental release had been greatly reduced by radioactive decay. The staff independently evaluated the offsite radiological consequences of the maximum credible accident in a defueled state.

Based on the staff's review of the Yankee Rowe analysis, the staff concurred with the licensee's

! accident analysis and concluded that there is no credible accident in the defueled condition that

( could result in the release of radioactive materials to the environment in quantities that would require prompt protective actions for the public.

Trojan

, The staff determined that the most significant potential accident associated with a permanently L defueled and shutdown reactor involves the spent fuel stored on site. The postulated accident sequence involved the complete or partial loss of water from a spent fuel pool containing recently off loaded fuel. This beyond-design-basis accident seqt ence could result in a zirconium fuel 1 cladding fire that could propagate through the spent fuel storage pool and result in significant

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offsite consequences. Although such an accident is beyond the design bases, it was considered within the spectrum of accidents that might be reasonably credible and that could require continuance of the offsite EP. It is also within the spectrum of beyond-design-basis accidents considered in NUREG-0396, " Planning Basis for the Development of State and Local Govemment Radiological Emergency Response Plans in Support of Ught Water Nuclear Power Plants," that formed the basis for NRC's emergency planning regulations from which the licensee sought exemption. A description of the accident sequence and estimates ofimpact are contained in NUREG-1353, " Regulatory Analysis for the Resolution of Generic issue 82, 'Beyond Design Basis Accident in Spent Fuel Pools.'" Consideration of this accident scenario was limited to the period of time that the spent fuel was thermodynamically capable of a cladding fire. This time period of concem had been estimated by the staff to be about 1 to 3 years following final shutdown depending on fuel bum-up and the spent fuel storage configuration.

The licensee subsequently justified to the staffs satisfaction that its spent fuel pool was designed to seismic criteria that essentially precluded a credible event that would lead to the loss of coolant inventory, thus, making the review criterion of a zirconium cladding fire moot.

Panel Conclusions on Assertion 1 The Panel finds that the Commission did not appear to explicitly consider the applicability of the backfit rule to decommissioning reactors. The staff is preparing a Commission paper that will address the applicability of the backfit rule to decommissioning plants. The Panel believes action on this Commission Paper should afford plants the same predictability, stability, and protection as operating reactors. Thus, the Panel has chosen to defer a conclusion on this matter on a generic basis. For the purposes of this appeal, the Panel simply assumed that the backfit rule applies to this specific licensee request. .

Assertion 2: The backfit rule should not distinguish between licensee initiated requests and NRC initiated actions.

The licensee stated that the backfit rule and its Statement of Considerations do not make the distinction in applicability based on the source of the proposed action. The licensee indicated that the backfit rule, by definition, relates to the imposition of new or additional requirements by the NRC. The licensee asserted that the NRC's position with respect to the Maine Yankee issue creates a distinction that does not exist in the backfit rule.

The Panel reviewed the applicable regulations and the staffs approach to evaluating the exemption request.

Panel Conclusion on Assertion 2 The Panel agrees with the licensee that the application of the backfit rule should not depend on whether the change comes from an NRC initiative or a licensee application.

Assertion 3: It is a violation of the backfit rule to review an exemption request against accident sequences and associated assumptions beyond those considered in the existing licensing basis.

. In order to evaluate this assertion, the Panel reviewed several relevant documents. These i

included NUREG-1353, the staffs efforts in granting EP exemptions for Rancho Seco, Yankee

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t Rowe, and Trojan (described above), and the agency's bases for imposing offsite EP regulations l (including NUREG-0396 and NUREG-0654). Also, the Panel reviewed SECY 93-127 (regarding Price-Anderson Exemptions) and its associated Staff Requirements Memorandum, and the ongoing staff efforts related to the proposed draft rulemaking on EP (SECY 97-120). The Panel's findings and analysis are summarized as follows.

1. Basis for Offsite EP Requirements l

NUREG-0396, " Planning Basis for the Development of State and Local Govemment Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants." and NUREG-0654, " Criteria for Preparation and Evaluation of Radiological Emergency Response Plans and Preparedness in Support of Nuclear Power Plants," discuss radiological emergency preparedness and the basis for planning response actions in the event of nuclear power plant accidents. These documents include consideration of generic beyond-design-basis accidents.

The underlying purpose of the offsite requirements is to ensure licensees follow and maintain in effect emergency plans that provide reasonable assurance that adequate protective measures can and will be taken in the event of an emergency at a nuclear reactor. To grant an exemption from the regulations, the staff need only conclude that reasonably credible beyond-design-basis accidents will not require offsite response capabilities.

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2. NUREG-1353, " Regulatory Analysis for the Resolution of Generic Issue 82, 'Beyond Design Basis Accidents in Spent Fuel Pools" The risk of beyond-design-basis accidents in spent fuel storage pools was examined in l

WASH-1400. It was concluded that these risks were orders of magnitude below those involving i

the reactor core because of the simplicity of the spent fuel storage pool design; in particular, (1) the coolant is at atmospheric pressure, (2) the spent fuel is always subcritical and the heat source is low, (3) there is no piping that can drain the pool, and (4) there are no anticipated operational transients that could interrupt cooling or cause criticality.

l The methods used to provide cooling for the removal of decay heat from the stored assemblies vary from plant to plant. The safety function to be performed remains the same; the spent fuel

assemblies must be cooled and must remain covered with water during all storage conditions.

Assuming that the water is drained or boiled off, the fuel rods will heat up until the buoyancy-driven air flow is sufficient to prevent further heat up. If the decay heat levelis high enough to heat the fuel rod cladding to about 900 *C (1650 *F), the oxidation becomes self-sustaining, resulting in a zirconium cladding fire. Propagation of the zirconium cladding fire to older adjacent assemblies is likely if the decay heat level in an older adjacent assembly is high enough to heat that assembly to within 100 to 200 *C (200 to 400 "F) of the self-sustaining oxidation temperature. Although propagation of a zirconium cladding fire to 1- to 2-year old fuel by only thermal radiation can occur, the older fuel would have to be next to the hottest assemblies.

I The risk from the storage of spent fuel in the spent fuel storage pool at light-water reactors is dominated by the beyond-design-basis earthquake accident scenario. The seismic capacities, or fragility, of two older spent fuel pools indicate that the high confidence of low probability of failure (HCLPF) is about three times the safe-shutdown earthquake (SSE) design level. The HCLPF l values are estimated to be in the 0.5 to 0.65 g range. The median peak ground acceleration needed to fail these pools is estimated to be in the 1.4 to 2.0 g range, nearly a factor of ten higher than the SSE design value. A report prepared by the American Society of Civil Engineers

also concluded that, in general, the seismic design of nuclear facility structures result in median l

factors of safety on the order of 4 to 19 based on post-1973 design criteria.

The structural capacity of the elevated boiling-water reactor (BWR) pool is lower than that for the pressurized-water reactor (PWR) pool located at ground level; however, the lower conditional j probability of a zirconium cladding fire for the BWR fuel assembly design offsets the higher seismic failure frequency. The probability of a zirconium cladding fire, resulting from the loss of water from the spent fuel pool, is estimated to have a mean value of 2 x 10-8 per reactor year for either the PWR or the BWR spent fuel pool. The seismic event contributes over 90 percent of the PWR spent fuel damage probability, and nearly 95 percent for the BWR.

The source term for the spent fuel pool accident is not the same as the source term associated with core damage accidents. The consequences of a spent fuel pool accident, which results in the complete loss of water, are dominated by the long lived isotopes such as cesium and strontium. The health consequences are dominated by the risk of latent cancer fatalities due to long-term exposures.

The risk and consequences of a spent fuel pool accident appear to meet the Safety Goal Policy

Statement objectives. The study concluded that most of the spent fuel pool risk is derived from l beyond-design-basis earthquakes, and that this risk is no greater than the risk from core damage accidents due to seismic events beyond the SSE. Therefore, reducing the risk from spent fuel l pools due to events beyond the SSE would stillleave at least a comparable risk due to core damage accidents. Because of the large inhemnt safety margins in the design and construction of the spent fuel pools, no action was deemed justified. Key facts from NUREG-1353:

For a zirconium clad fire to occur, the fuel ruust be recently discharged (between 30 and 180 days in a cylindrical BWR configuration, and between 30 and 250 days in a cylindrical PWR configuration).

For a less severe accident in which the fuel is exposed to air, but does not reach

! temperatures high enough to ignite the zirconium cladding, fuel pin failure could occur, l resulting in a release of the noble gases and halogens.

For spent fuel accidents, there are no "early fatalities" and the risk of early injury is negligible.

j For a severe core damage accident, early fatalities and early injury are part of the risk due to the presence of short-lived isotopes. For the long-lived isotopes (predominately cesium), the exposure is due mainly to exposure after the area is decontaminated and people retum to their homes.

Most of the spent fuel pool risk is derived from beyond-design-basis seismic events. For operating plants, the spent fuel pool risk is no greater than the risk from core damage accidents due to seismic events beyond the SSE. Potentialimprovements to the spent fuel pool cooling and make-up systems were also examined. The potential risk to the general public is estimated to be very small, on the order of three to four person-rem, given a loss of cooling event, which results in failure of the spent fuel cladding, but not a cladding fire. Reducing the spent fuel pool j risk would not affect the overall risk of an operating plant to any significant degree.

i The Panel believes that in the circumstances of this case, a zirconium cladding fire resulting from i a drain down of the spent fuel pool is so unlikely, especially after significant decay time, that it need not be considered in acting on Maine Yankee's exemption request.

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i j 3. Price-Anderson Exemptiorgs The staff stated the following in SECY 93-127, " Financial Protection Required of Licensees of Large Nuclear Power Plants During Decommissioning:" "...the most significant accident l! sequence for a permanently defueled and shutdown reactor involves the complete loss of water i from a light water reactor spent fuel pool. This beyond design basis accident could result in a zirconium fuel cladding fire that could propagate through the spent fuel storage pool and result in significant off site consequences....Although such an accident is beyond the design bases, it may be considered ' reasonably credible' and could warrant requiring substantial financial protection.

j Such an accident is possible during the first year after reactor shutdown for a low density spent 1

fuel storage configuration and during the first 2 to 3 years after shutdown for spent fuel stored in i certain high density configurations."

l The Commission's response to SECY 93-127 required the staff to issue Price-Anderson i

exemptions for permanently shutdown plants after a case-by-case review.

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The Panel notes that the criteria used by the staff for granting relief from Price-Anderson may be i different than the criteria used in granting exemptions to EP. The protection afforded by offsite I j EP may be relaxed well before the financial protection associated with Price-Anderson.

l 4. EP Draft Rulemaking l The staff has undertaken rulemaking that will simplify the review and approval process for EP regulations. On July 10,1997, the Commission approved Option 2 of SECY 97-120, i

"Rulemaking Plan for Emergency Planning Requirements for Permanently Shutdown Nuclear Power Plant Sites 10 CFR Part 50.54(q) and (t),10 CFR 50.47, and Appendix to 10 CFR Part 50." The proposed rulemaking would allow power reactor licensees to obtain relief from EP requirements during permanent shutdown. Under specified conditions and subject to NRC i approval, licensees would be allowed to modify their EP requirements if they met the following j conditions: (1) the reactors onsite are defueled and permanently shutdown; (2) spent fuel in the 3

spent fuel pools is no longer susceptible to a zirconium cladding fire or gap release caused by an i incipient fuel cladding failure in the event the spent fuel pool is drained accidentally; and (3) a

! site-specific analysis of the onsite inventory of radioactive material has determined that in the event of a release, no member of the public would be exposed to doses in excess of the EPA PAGs. After spent fuel has cooled down to a point where the spent fuel cladding temperature would not exceed 565 'C following an accidental draining of the spent fuel, licensees would be allowed to modify their EP requirements. The cladding temperature limit of 565 *C would be reached after a decay period of 17 months for PWRs and 7 months for BWRs (according to NUREG/CR-6451, "A Safety and Regulatory Assessment of Generic BWR and PWR Permanently Shutdown Nuclear Power Plants," prepared by Brookhaven National Laboratory).

The Panel notes the efforts of the staff appear to support a time-sensitive criteria in lieu of a comprehensive case-by-ease technical evaluation. This approach will significantly reduce staff and licensee time and effort and result in a fully predictable process.

Panel Conclusion on Assertion 3 The staff first used the spent fuel pool fire as a limiting safety concem during the review of the Trojan EP exemption request. Subsequent to the Trojan review, spent fuel pool fires were used

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by the staff in proposals to the Commission for Price-Anderson exemptions and in generic 1 rulemaking for processing EP' exemptions for decommissioning plants.

1 The Panel finds, in addition to the history associated with the use of the subject criteria, that no backfit occurred when this criterion was used by the staff in evaluating Maine Yankee's l exemption request. Indeed, Maine Yankee recognized the need for this analysis and included such an analysis in its January 20,1998, submittal. However, the Panel believes that the staff l sought to develop an absolute safety finding rather than a risk-informed reasonable assurance l finding.

While the use of the zirconium clad fire is a conservative criterion for evaluating EP exemption ,

requests for decommissioning plants, it remains unclear that this is the appropriate criterion in all circumstances. Maine Yankee argued that sufficient technical bases exist to grant the EP exemption shortly after off-loading all fuel to the spent fuel pool. A reasonableness test along with a risk-informed perspective and a realistic consideration of the likelihood that the spent fuel pool could be drained in the first place appears to justify this view. NUREG-1353 provides a quantitative analysis of the potential radiologicalimpact of radioactivity released to the environs from a buming spent fuel versus the number of days fuel has been stored. The impact of radioactivity rel cases decreases from about 2,600,000 to 4 person-rem (whole body dose) over a 1-year period. Thus, a simplistic and quantifiable figure of merit already exists, which is clear and easily understood. Additional complex analyses of heat-up rates and extensive reviews of computer codes as the staff initially requested in this case are not required.

I l in addition, the NUREG-1353 analysis did not assume a prompt, planned evacuation. It did assume that after i day of radioactivity releases associated with the spent fuel fire, people would be relocated. The analysis also indicated that no substantial acute individual doses would occur.

There is not a clear nexus that relates the need for the comprehensive EP with the l characteristics of a spent fuel pool fire. The Panel concludes that the staff had ample opportunity to establish reasonable assurance that the public health and safety was protected without going into such technical depth.

Assertion 4: A NUREG cannot be used as the basis to impose new or additional requirements for licensees.

l Panel Conclusion on Assertion 4 It is well known by the staff that NUREGs do not themselves impose requirements on licensees. There are intemal NRC procedures that must be followed before any requirements can be imposed. Technicalinsights and analyses contained in NUREGs can be used by the staff to support evaluations that are part of the staff's routine functions and could form the l foundation for the imposition of a requirement through other appropriate means.

1 In this case, the Panel notes that NUREG-1353 was used by the staff to identify accidents that could have offsite radiological impact justifying the continuation of offsite emergency preparedness while undergoing decommissioning. The Panel agrees that the staff appropriately used some of the analyses in NUREG-1353; viz., in identifying potentially significant safety

concems while undergoing decommissioning. However, as previously discussed, the staff l

could have relied on NUREG-1353 and concluded that EP is no longer required at a finite

period of time after the reactor was completely defueled and, thus, had sufficient information to make the findings required to grant an exemption.

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Assertion 5: The licensee fprther characterized another regulatory burden imposed by the staff to be a backfit: viz., the licensee was required not only to perform an acceptable analysis but also to provide the NRC with information, support, and assistance, as necessary, to allow the NRC to perform its own analysis verifying the licensee's fulfillment of the criterion.

Panel Conclusion on Assertion 5 The staff can always seek information needed to evaluate licensee requests with the condition that the information requested must have a reasonable nexus to the findings that the NRC must make to act on the licensee's request. Management must ensure that information requests meet this standard. This conclusion was confirmed by the Office of the General Counsel, in processing exemption requests, the underlying regulation,10 CFR 50.12, states, among other things that "[a]pplication of the regulation in the particular circumstances would not serve the underiying purpose of the rule or is not necessary to achieve the underlying purpose of the rule." The staff, therefore, must make a fundamental finding that circumstances have changed sufficiently to warrant consideration of the exemption and a technical argument exists which provides sufficient justification to support the proposed exemption.

To reach a determination that sufficient basis exists to meet the requirement of 10 CFR 50.12, the staff may need to seek information necessary to make a safety finding. In cases involving offsite EP requirements, the requirement of ensuring adequate public health and safety may result in evaluations that go beyond the design basis because the offsite EP requirements are based on beyond design basis accidents. Design basis events are typically postulated in performing plant reviews with the distinction that these events do not yield releases to the environs which exceed Part 100 limits.

Therefore, the staff"s use of a postulated zirconium clad fire is appropriate to ensure that even under the most challenging potential" worst-case scenarios," the public health and safety remain protected as long as the zirconium clad fire remains as a reasonably credible event.

IV.

SUMMARY

The Panel finds that the staff acted prudently and appropriately in applying criteria deemed necessary to make a safety finding to develop rationale and basis to support an exemption to 10 CFR 50.47. Based on the preceding discussion, the Panel finds no inconsistency with the application of 10 CFR 50.109 to the extent that a zirconium clad fire was reasonably credible.

The Panel believes that the concems and questions raised by the staff in response to the request made by the licensee were appropriate. The Panel believes the criteria are defensible, albeit overty conservative. Management oversight, accountability and related NRC expectations should be focused to ensure staff questions and positions are germane to the topic. The scope and depth of technical reviews are management issues and management must ensure that absolutes are not the goal of the technical reviews but risk-informed reasonableness tests are maintained.

However, the most compelling observation was the lack of staff sensitivity to elapsed time and schedules confronting decommissioning nuclear power plants. Time-sensitive review criteria will focus the staff on issues of higher safety concem and allow the NRC to be a predictable

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regulator, if done effectively, the NRC will be consistent and predictable in the decommissioning area. In this case, the staff should have considered whether the zirconium clad fire was reasonably credible in view of either the seismic design of the spent fuel pool (as it did in Trojan) or the time elapsed since the reactor was permanently shut down.

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j v#% Enclosure 2 g/ $4 UNITED STATES g NUCLEAR REGULATORY COMMISSION

1. WASHINGTON, D.C. m i " WN

• • • • • November 6, 1998 MEMORANDUM TO: Jack W. Roe, Acting Director Division of Reactor Program Management Office of Nuclear Reactor Regulation FROM: ector Office of Nuclear Reactor Regulation

SUBJECT:

RECOMMENDATIONS OF BACKFIT REVIEW PANEL i

In a memorandum dated October 28,1998, the members of the backfit review panel i assigned to review a May 6,1998, appeal filed by Maine Yankee Atomic Power Company sent its recommendations to me. Although the panel determined that the staff did not impose a backfit on Maine Yankee with respect to the criteria being used by the staff in evaluating a Maine Yankee request for relief from offsite emergency preparedness requirements of 10 CFR 50.54(q), it did make other recommendations regarding the criteria being used by the staff in its evaluation of emergency planning exemptions being sought by permanently shutdown and defueled reactors.

l Please respond to the review panel's observations that the staff lacked sensitivity to the elapsed time and schedules confronting decommissioning nuclear power plants. You should address how the NRC will maintain consistency and predictability in the l

decommissioning area. Send a schedule of your proposed actions to me by November 30, 1998.

l In addition, please recommend how this process could be done more effectively and how technical criteria could be developed for future exemptions.

l CONTACT: Michael Webb, DRPM/NRR 415-1347 l

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