Revised Criteria for Post Accident Sampling Systems

[Federal Register Volume 64, Number 226 (Wednesday, November 24, 1999)]
[Notices]
[Pages 66213-66214]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-30645]


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NUCLEAR REGULATORY COMMISSION


Revised Criteria for Post Accident Sampling Systems

AGENCY: Nuclear Regulatory Commission.

ACTION: Request for comment.

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SUMMARY: The Nuclear Regulatory Commission (NRC) is considering 
modifying its criteria for post accident sampling systems (PASS). The 
NRC has received two industry-developed topical reports which provide 
justification for removal of PASS from the licensing basis for nuclear 
power plants designed by Westinghouse and Combustion Engineering. The 
NRC generally agrees with the conclusions in these reports and is 
considering approving these reports. If the NRC approves these reports, 
nuclear power plant licensees will be able to reference the reports to 
support changes to their PASS, including the elimination of the system. 
The NRC is requesting public comment on this pending action. In 
particular, the NRC is seeking comment on whether the elimination of 
information obtained from radionuclide sampling from PASS may affect 
offsite emergency response organizations ability to respond to an 
accident.

DATES: The comment period expires January 10, 2000. Comments received 
from after this date will be considered if it practical to do so, but 
the Commission is able to ensure consideration only for comments 
received on or before this date.

ADDRESSES: Submit comments to: David L. Meyer, Chief, Rules and 
Directives Branch, U.S. Nuclear Regulatory Commission, Washington, DC, 
20555-0001, Attention: Rulemakings and Adjucations Staff.
    Deliver comments to: 11555 Rockville Pike, Rockville, Maryland, 
between 7:30 a.m. and 4:15 p.m. on Federal workdays.
    The publications cited in this document, including the industry-
developed topical reports, are available for inspection and copying, 
for a fee, through the NRC Public Document Room, 2120 L Street, Lower 
Level, Washington, DC.

FOR FURTHER INFORMATION CONTACT: James O'Brien, Office of Nuclear 
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC. 
20555-0001, telephone (301) 415-2919; e-mail jbo@nrc.gov.

SUPPLEMENTARY INFORMATION: 

I. Background
II. Description of Proposed Action
III. Evaluation of Proposed Action
IV. Request for Comment


I. Background

    Following the accident at Three Mile Island Unit 2 (TMI-2) on March 
28, 1979, the NRC formed a lessons-learned Task Force to identify and 
evaluate safety concerns originating with the TMI-2 accident. NUREG-
0578, ``TMI-2 Lessons Learned Task Force Status report and Short-term 
Recommendations,'' documents the results of the task force effort. One 
of the recommendations of the task force was for licensees to upgrade 
the capability to obtain samples from the reactor coolant system and 
containment atmosphere under high radioactivity conditions and to 
provide the capability for chemical and spectral analyses of high-level 
samples on site. NUREG-0737, ``Clarification of TMI Action Plan 
Requirements,'' which was issued to licenses in Generic Letter 80-90 on 
October 31, 1980, contains the details of the TMI recommendations that 
were to be implemented by the licensees. Additional criteria for post 
accident sampling systems were issued by Regulatory Guide 1.97, 
``Instrumentation for Light-water-cooled Nuclear Power Plants to Assess 
Plant and Environs Conditions During and Following an Accident.''
    Specific criteria for PASS capability delineated in NUREG-0737 and 
Regulatory Guide 1.97 are:

------------------------------------------------------------------------
            Sample location                        Measurement
------------------------------------------------------------------------
1. Reactor Coolant.....................  Dissolved gases, Boron,
                                          Chlorides, pH, Radionuclides
2. Containment Atmosphere..............  Hydrogen, Oxygen, Radionuclides
3. Containment Sump....................  Boron, Chlorides, pH,
                                          Radionuclides
------------------------------------------------------------------------

    All samples and measurements were to be taken and analyzed within 3 
hours of the decision to do so except for chlorides which were to be 
taken and analyzed within 24 hours.
    In the mid 1980's, the NRC sponsored an assessment of selected 
regulatory requirements that may have marginal importance to risk. One 
of the issues reviewed was the PASS criteria. This assessment, 
documented in NUREG/CR-4330, concluded that the PASS had marginal 
benefits, but that the cost of maintaining the PASS was minimal.
    On October 26, 1998, the Westinghouse Owners Group submitted a 
topical report, WCAP-14986-P which provided justification for 
elimination of the PASS from the licensing basis. By eliminating PASS 
from the licensing basis, there would no longer be a licensee 
commitment to maintain the system. On May 5, 1999, the Combustion 
Engineering Owners Group

[[Page 66214]]

submitted a related topical report, CE NPSD-1157, which also provided 
justification for elimination of PASS. Both of these topical reports 
indicated that the cost of maintaining the PASS was high and justified 
elimination of PASS based upon there being no benefit in the 
information obtained via PASS. The topical reports conclude that the 
sampling systems are not useful in supporting post accident mitigative 
and emergency response actions and that most of the information, which 
would be obtained from sampling, can be inferred from other indications 
which will be available earlier in an event that the sample results. In 
addition, the topical reports state that the samples are subject to 
inaccuracies due to physical phenomena (e.g., deposition of fission 
products in sample lines) involved in taking the samples.

II. Description of Proposed Action

    The NRC is proposing to endorse the industry topical reports for 
referencing in site-specific licensing actions to remove commitments 
for maintaining PASS. This action, if taken, would allow nuclear power 
plants to remove their commitments for maintaining PASS.

III. Justification for Proposed Action

    The NRC concludes from its review of the topical reports that the 
information to be obtained from PASS can be inferred to a large degree 
from other indications which will be available earlier in an event than 
the PASS samples due to the time needed to obtain and analyze the PASS 
sample. In addition, the PASS samples are difficult to obtain and are 
subject to inaccuracies due to physical phenomena (e.g., deposition of 
fission products in sample lines) involved in taking the samples. 
However, PASS can provide a measurement of radionuclides in reactor 
coolant system, containment sump and containment atmosphere which may 
be used in supporting emergency response decision making. This 
information may be used to modify the assumed source term used in 
offsite dose calculations which are considered in formulating 
Protective Action Recommendations (PARs) during an accident. This 
information is not needed to formulate initial PARs (which are most 
likely based on plant conditions, e.g., reactor water level, core 
temperatures, and containment radiation levels). Furthermore, other 
information, such as area, process, and effluent radiation monitor 
readings and field team data, can be used to support modification to 
the initial PAR. The PASS information would potentially be most useful 
in situations where an accident results in release of radioactive 
material to the reactor coolant or containment, but a breach of either 
of these systems/volumes does not occur within the first several hours 
of the accident or occurs through an unmonitored release path. However, 
even in these situations, PASS sample measurement information would not 
be a real-time indication of the concentration of radionuclides within 
the sampled volume (due to the time needed to analyze the samples) and 
would be subject to the inaccuracies discussed above.

IV. Request for Comment

    Before completing its review of the industry topical reports, the 
NRC is seeking public comment from its stockholders. In particular, the 
NRC is seeking comment from offsite emergency response organizations 
who may have an interest in information regarding radionuclide 
concentrations in the reactor coolant, containment sump or containment 
atmosphere to support their emergency response activities (in 
particular protective action decision making). Specifically, the NRC is 
seeking comment on whether elimination of information obtained from 
radionuclide sampling using the PASS may have an adverse effect on 
offsite emergency response organizations' ability to respond to an 
accident in view of (1) the availability of information provided by 
plant conditions, plant radiation monitor readings and field monitoring 
teams and (2) the limitations associated with the accuracy and 
timeliness of information provided by the PASS.

    Dated at Rockville, Maryland, this 18 day of November, 1999.

    For the Nuclear Regulatory Commission.
Frank P. Gillespie,
Deputy Director, Division of Inspection Program Management, Office of 
Nuclear Reactor Regulation.
[FR Doc 99-30645 Filed 11-23-99; 8:45 am]
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