목차

List of Figures ···························································································· iv
List of Tables ····························································································· vi
제1장 서론 ·································································································· 1
제2장 SPND 특성 ······················································································ 7
2.1 중성자 반응을 이용하는 SPND ··················································· 9
2.1.1 중성자와 지연 반응을 하는 SPND ······································ 9
2.1.2 중성자와 즉발 반응을 하는 SPND ···································· 10
2.2. 감마선 반응을 이용하는 SPND ················································ 10
2.3 계측기 집합체 ················································································ 11
2.4 로듐 계측기와 백그라운드 계측기 ··········································· 12
2.5 운전 원리 ······················································································· 13
2.6 SPND 반응 메커니즘 ··································································· 14
2.6.1 (n, β) 상호작용 ······································································· 14
2.6.2 (n, γ, e) 상호작용 ·································································· 15
2.6.3 (γ, e) 상호작용 ······································································· 15
2.7 공간하전효과 (Space Charge Effect) ·········································· 16
제3장 SPND 중성자 민감도 계산 수학적 모델 ································ 18
3.1 중성자 포획량 ··············································································· 19
3.1.1 중성자 자기차폐 보정인자 ·················································· 20
3.1.2 중성자속 감쇠(depression)에 대한 보정 ····························· 22
3.2 베타 이탈확률 ··············································································· 23
3.2.1 전자의 생성확률 (베타 에너지 스펙트럼) ························ 24
3.2.2 전자의 경로길이, 에너지 보정 ··········································· 25
3.3 임계거리(Critical Distance) 및 Emin 유도 ·································· 30
3.4 SPND의 공간하전효과에 의한 영향 ········································· 34
3.4.1 에미터 직경에 의한 영향 ···················································· 34
3.4.2 절연체의 직경과 밀도로 인한 영향 ·································· 35
제4장 SPND 중상자 초기 민감도 계산 (Static Model) ···················· 36
4.1 바나듐 SPND 초기 민감도 계산을 위한 MCNP 모델 ·········· 36
4.1.1 51V의 중성자 포획단면적 ····················································· 37
4.1.2 자기차폐인자 ·········································································· 38
4.1.3 베타 이탈확률 (ε) ·································································· 39
4.2 공간하전 영향 평가 모델 ··························································· 40
4.3 MCNP 모사계산 ············································································ 42
4.4 평가 결과 ····················································································· 45
제5장 SPND 연소 민감도 계산 (Depletion Model) ··························· 47
5.1 Analytic 계산 모델 ······································································ 49
5.1.1 베타붕괴에 의한 전류 계산 ················································ 49
5.1.2 감마에 의한 전류 계산 ······················································ 51
5.2 MCNP 계산 모델 ·········································································· 51
5.2.1 베타붕괴 전자의 에너지 스펙트럼 계산 ·························· 53
5.2.2 베타붕괴율 계산 ·································································· 54
5.2.3 흡수반응률 계산 ···································································· 54
5.2.4 전자이탈확률 ·········································································· 55
5.2.5 감마선 반응 ············································································ 57
5.3 민감도 평가인자 계산 및 분석 ················································· 57
5.4 연소계산 ························································································· 62
5.4.1 연소계산 조건 ······································································ 62
5.4.2 평균 중성자속 계산 ······························································ 64
5.5 에미터 연소에 의한 물질 변화 ················································· 65
5.5.1 로듐 에미터 ·········································································· 65
5.5.2 바나듐 에미터 ········································································ 68
5.6 민감도 계산결과 ··········································································· 70
5.6.1 에미터 연소에 따른 민감도 변화 ···································· 70
5.6.2 계산모델 검증 ········································································ 73
제6장 SPND 민감도 평가 모사 계산 ·················································· 75
6.1 장수명 노내계측기에 적용할 바나듐 SPND 민감도 평가 ··· 75
6.2 로듐 및 바나듐 SPND의 장수명 적합성 평가 ······················· 79
6.3 SMART 및 SMR 적용 SPND의 민감도 평가 ························· 82
6.4 로듐 SPND 제원 변경에 따른 수명기간 동안 민감도 변화 89
6.4.1 에미터 반지름 변경에 대한 민감도 변화 ························ 89
6.4.2 절연체 두께 변경에 대한 민감도 변화 ···························· 91
제7장 결론 ································································································ 93
참고문헌 ···································································································· 97
Abstract ····································································································· 101