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Environmental Assessment and Finding of No Significant Impact Related to Issuance of Exemption for the Humboldt Bay Power Plant Unit 3 License DPR-007, Humboldt, CA

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U.S. Nuclear Regulatory Commission.


Environmental Assessment and Finding of No Significant Impact.

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John Hickman, Division of Waste Management and Environmental Protection, Office of Federal and State Materials and Environmental Management Programs, U.S. Nuclear Regulatory Commission, Mail Stop: T8F5, Washington, DC 20555-0001. Telephone: (301) 415-3017; e-mail:

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I. Introduction

The U.S. Nuclear Regulatory Commission (NRC) staff is considering a request dated October 30, 2007, by the Pacific Gas and Electric Company (PG&E or the Licensee), to approve a request for exemption from the values of the Inhalation Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) that appear in 10 CFR Part 20, Appendix B, Table 1, for use at Humboldt Bay Power Plant, Unit 3 (HBPP). PG&E proposes replacing the 10 CFR Part 20, Appendix B, Table 1 ALI and DAC values, derived using previous (1977) recommendations of the International Commission on Radiological Protection (ICRP), with ALI and DAC values derived using more recent (1995) ICRP recommendations.

This Environmental Assessment (EA) has been developed in accordance with the requirements of 10 CFR 51.21.

II. Environmental Assessment


HBPP was permanently shut down in July 1976, and until recently was in safe storage condition (SAFSTOR). SAFSTOR is defined as a method of decommissioning in which the nuclear facility is placed and maintained in safe condition for an extended period of time to permit radioactive material to decay to levels that facilitate subsequent decontamination and decommissioning of the facility. A Decommissioning Plan was approved in July 1988. Subsequent to the 1997 decommissioning rule, the licensee converted its decommissioning plan into its Defueled Safety Analysis Report which is updated every two years. A Post Shutdown Decommissioning Activities Report was issued by the licensee in February 1998. In December 2003, PG&E formally submitted a license application to the NRC for approval of a dry-cask Independent Spent Fuel Storage Installation (ISFSI) at the Humboldt Bay site. A preliminary license and safety evaluation report for the Humboldt Bay ISFSI was issued on August 24, 2005. The ISFSI is currently under construction and the licensee is now engaged in some incremental decommissioning activities.

Fuel failures occurred at HBPP in the past when the reactor was operating, resulting in contamination from alpha emitters which pose an inhalation hazard to workers. The inhalation of airborne radioactive materials in restricted areas poses a potential internal radiation hazard and the NRC regulations in 10 CFR Part 20 require licensees to assess these radiation hazards and to implement protective measures to minimize that hazard to workers, the public and the environment. These actions and measures include air sampling, posting airborne radioactivity area warning signs, the use of respiratory protection, and bioassay monitoring of workers. These actions and measures are triggered when air concentrations in the workplace reach specified fractions of the DAC values in 10 CFR Part 20, Appendix B.

Proposed Action

HBPP has requested that NRC allow an exemption under 10 CFR 20.2301 to allow the use of DAC and ALI values calculated using ICRP-68, “Dose Coefficients for Intake of Radionuclides by Workers,” (Ref. 3) dose coefficients and parameters instead of the DAC and ALI values in 10 CFR Part 20, Appendix B, Table 1, Occupational Values. HBPP believes that this change will result in greater worker efficiency in decommissioning work activities and should result in an overall reduction in worker dose. The ICRP 68 parameters used in calculating DAC and ALI values are generally accepted as more representative models of the actual Start Printed Page 3758physical and biological mechanisms involved in the inhalation and deposition of aerosols in the human body. The Department of Energy (DOE) adopted the ICRP-68 recommendations for DAC and ALI values in a revision to 10 CFR Part 835, Occupational Radiation Protection, earlier this year (Ref. 4). Also, the Commission has indicated in Staff Requirements Memoranda for SECY-01-148 (Ref. 5) and SECY-99-077 (Ref. 6) that the NRC staff should consider and approve, as appropriate, licensee requests to use more recent ICRP radiation protection recommendations on a case-by-case basis. The licensee states that the exemption is allowed by NRC regulations and will not result in any new or increased hazard to life of property.

Need for Proposed Action

To protect plant workers from doses due to inhalation of alpha emitters, the HBPP internal exposure control program requires the use of respirators when performing certain activities. Using a respirator reduces worker efficiency and requires workers to remain in radiation areas longer than if respirators were not used. By remaining in a radiation area longer than necessary, workers receive higher external doses due to gamma radiation. At the present time, plant workers are actively performing preparatory decommissioning activities that are scheduled to increase in mid-2008 after spent nuclear fuel assemblies and fuel fragment containers are transferred from the spent fuel pool to the ISFSI.

III. Environmental Impacts of the Proposed Action

Radiological Impacts

The DAC and ALI values in 10 CFR Part 20, Appendix B, Table 1, were calculated using ICRP 26 and ICRP 30 radiation dosimetry methodology. This methodology was adopted by the ICRP in 1977 and 1978, respectively. The ICRP has continued to update and revise its dosimetric models and input parameters as new information became available. The current ICRP basic radiation protection recommendations are in ICRP 60 which was adopted in 1991. HBPP proposes to use the dose coefficients for intake of radionuclides by workers in ICRP-68 which were adopted for use by ICRP in 1995.

The differences in the values between the current NRC DAC values and values for most radionuclides using more recent ICRP methodology are generally two-fold or less. However, the difference between some radionuclides is larger—especially for uranium and some of the transuranic radionuclides. HBPP has provided a comparison of inhalation ALIs for these radionuclides. ICRP-68 inhalation ALI values are greater than ICRP-30 values by a factor of 4.9 for U-235; 6.1 for Pu-238; 2.0 for Am-241; and 5.0 for Np-237.

Engineering controls are the preferred method to control airborne radioactive materials, but this is more difficult to implement for the changing conditions in decommissioning activities than during routine operations. The use of ICRP-68 dose coefficients and parameters to develop DAC and ALI values should result in less conservative values than those currently in 10 CFR Part 20. This should reduce the reliance on respirators to prevent the inhalation of airborne radioactivity by workers, and this should improve worker's ability to better identify and avoid industrial safety hazards and also should reduce physical stresses on workers. The reduced reliance on respirators will also allow workers to perform activities in radiation areas more efficiently, reducing external radiation dose due to gamma rays, and resulting in reduced overall dose received. Therefore, PG&E's request for an exemption under 10 CFR Part 20.2301 is acceptable because it gives its workers equivalent radiological protection as required by 10 CFR Part 20.

Non-Radiological Impacts

The NRC has determined that there are no adverse non-radiological impacts associated with the proposed action.

Cumulative Impacts

The NRC has determined that there are no adverse cumulative impacts associated with this proposed action.

Alternatives to the Proposed Action

The alternative to considering the exemption request for approval is to deny the request. The alternative was rejected by NRC because the impacts on workers, the public and the environment were not adversely affected by the requested action. The use of ICRP 68 recommendations to calculate DAC and ALI values should reduce potential industrial safety hazards to workers by lessening reliance on respirators and will not increase any hazards to the public or the environment.

Agencies and Persons Consulted

The NRC contacted the California Radiologic Health Branch in the State Department of Health Services concerning this request. There were no comments, concerns or objections from the state official.

NRC staff determined that the proposed action is not a major decommissioning activity and will not affect listed or proposed endangered species, nor critical habitat. Therefore, no further consultation is required under Section 7 of the Endangered Species Act. Likewise, NRC staff determined that the proposed action is not the type of activity that has the potential to cause previously unconsidered effects on historic properties, as consultation for site decommissioning has been conducted previously. There are no additional impacts to historic properties associated with the disposal method and location for demolition debris. Therefore, no consultation is required under Section 106 of the National Historic Preservation Act.

IV. Finding of No Significant Impact

On the basis of the environmental assessment, the NRC concludes that the proposed action will not have a significant effect on the quality of the human environment. Accordingly, the NRC has determined that preparation of an environmental impact statement is not warranted for the proposed action.

V. Further Information

For further information with respect to the proposed action, see the following documents:

1. J. S. Keenan, Pacific Gas and Electric Company, letter to the U.S. Nuclear Regulatory Commission, “Exemption Request From 10 CFR 20 Appendix B, Table 1 Values,” October 30, 2007. (ML073060034)

2. U.S. Code of Federal Regulation, “Standards for Protection Against Radiation,” Part 20, Chapter 1, Title 10, Energy.

3. International Commission on Radiological Protection Publication 68, Dose Coefficients for Intakes of Radionuclides by Workers, published July, 1994 (ISBN 0 08 042651 4). This document is available from Elsevier Science Inc., Tarrytown, NY.

4. Federal Register Notice, Friday, June 8, 2007 (FR Vol. 72, No.110, Pages 31904—31941), DOE Final Rule for the adoption of current ICRP methodology for DAC and ALI values in 10 CFR 835, Occupational Radiation Protection.

5. SR-SECY-01-148, Staff Requirements—SECY-01-0148—Processes for Revision of 10 CFR Part 20 Regarding Adoption of ICRP Recommendations on Occupational Dose Limits and Dosimetric Models and Parameters, April 12, 2002. (ML011580363) Start Printed Page 3759

6. SR-SECY-99-077, Staff Requirements—SECY-99-0077—To Request Commission Approval to Grant Exemptions From Portions of 10 CFR Part 20, April 21, 1999. (ML042750086)

The NRC Public Documents Room is located at NRC Headquarters in Rockville, MD, and can be contacted at (800) 397-4209. Documents may be examined, and/or copied for a fee, at the NRC's Public Document Room (PDR), located at One White Flint North, 11555 Rockville Pike (first floor), Rockville, Maryland. Publicly available records will be accessible electronically from the Agencywide Documents Access and Management System's (ADAMS) Public Library component on the NRC Web site, (the Public Electronic Reading Room). Persons who do not have access to ADAMS or who encounter problems in accessing the documents located in ADAMS should contact the NRC PDR Reference staff by telephone at 1-800-397-4209, or 301-415-4737, or by e-mail at

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Dated at Rockville, Maryland, this 15th day of January, 2008.

For the Nuclear Regulatory Commission.

Keith I. McConnell,

Deputy Director, Decommissioning and Uranium Recovery Licensing Directorate, Division of Waste Management and Environmental Protection, Office of Federal and State Materials and Environmental Management Programs.

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[FR Doc. E8-987 Filed 1-18-08; 8:45 am]