1、Lessons Learned Entry: 1071Lesson Info:a71 Lesson Number: 1071a71 Lesson Date: 1998-02-01a71 Submitting Organization: HQa71 Submitted by: David M. LengyelSubject: International Space Station (ISS) Program/Radiation Exposure/Effects on Crew Description of Driving Event: Effects of Radiation Exposure
2、on ISS Expedition CrewsLesson(s) Learned: Radiation exposures of U.S. astronauts recorded over several Mir missions of 115 to 180 days duration have been approximately 10.67 to 17.20 REM. If similar levels of exposure are experienced during ISS operations, the cumulative effects of radiation could a
3、ffect crew health and limit the number of ISS missions to which crewmembers could be assigned.Recommendation(s): Determine projected ISS crew radiation exposure levels. If appropriate, based on study results, initiate a design program to modify habitable ISS modules to minimize such exposures or lim
4、it crew stay time as required.Evidence of Recurrence Control Effectiveness: Crew radiation exposure requirements for the primary elements of the United States On-orbit Segment (USOS), including the habitation and laboratory modules, as defined in the Primary Item Development Specifications (Section
5、3.3.10.3) state the design of these modules shall limit the ionizing radiation dose to crew members to 40 Roentgen equivalent man (rem) Blood Forming Organs (BFO) per year. This requirement was developed in coordination with the JSC Space Radiation Analysis Group and is more stringent than the overa
6、ll NASA Flight Rule requirement (14-10) of 50 rem BFO per year. This requirement also meets the intent of the Presidential Directive concerning Federal Radiation Protection Guidance for Occupational Exposure (Federal Register Vol. Provided by IHSNot for ResaleNo reproduction or networking permitted
7、without license from IHS-,-,-52, No. 17). Detailed analyses documented in SAIC-TN-96065 (August 1996) and SAIC-TN-9601 (January 1996) indicates that the maximum dose for any location in the USOS is less than 23 rem BFO per year.Detailed shielding analyses performed by Khrunichev and documented in EN
8、10-13, Protection from Space Environment (November 1996), indicate calculated values of absorbed dose in the FGB crew-habitable zone range from 16-39 rads/year. Using a quality factor value of 1.4 obtained from NCRP Report No. 98 (Guidance on Radiation Received in Space Activities pg. 45) to conver
9、t from rads to rem gives 22-55 rem per year. Based on these analyses and the nominal crew rotation schedule (90 days on-orbit, not to exceed 180 days), ISS concludes that adequate protection is provided to the crew by the shielding and design of the ISS.In addition, the federal guideline is an expos
10、ure of 50 rem BFO per year. The International Space Station requirement is 40 rem BFO per year. Current analysis of USOS predicts maximum exposure of 16 rem BFO per year. Although the actual crew exposure level will be monitored with actual flight data, the ISSP concludes that no redesign is necessa
11、ry to consider increased shielding requirements.Technical Reference: Letter from Boeing Environments Team dated February 12, 1998Documents Related to Lesson: N/AMission Directorate(s): a71 Space Operationsa71 Exploration SystemsAdditional Key Phrase(s): a71 Aerospace Safety Advisory Panela71 Flight
12、Operationsa71 Medicala71 Occupational Healtha71 Risk Management/Assessmenta71 Safety & Mission AssuranceAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 2002-01-07a71 Approval Name: Bill Loewya71 Approval Organization: HQa71 Approval Phone Number: 202-358-0528Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
